INVITED REVIEW
Transcription factors in mouse lung development and function

Robert H. Costa, Vladimir V. Kalinichenko, and Lorena Lim

Department of Molecular Genetics, College of Medicine, University of Illinois at Chicago, Chicago, Illinois 60607-7170


    ABSTRACT
TOP
ABSTRACT
INTRODUCTION
IDENTIFICATION OF HNF-3 IN...
EXPRESSION OF FORKHEAD BOX...
MESENCHYMAL EXPRESSION OF HFH-8...
THE FOX TRANSCRIPTION FACTOR...
EXPRESSION OF FKH6 (FOXL1)...
EXPRESSION OF HFH-11B (FOXM1B)...
THE HOMEOBOX TRANSCRIPTION...
HOX TRANSCRIPTION FACTORS IN...
ROLE OF THE ZINC...
CUBITUS INTERRUPTUS GLI...
THE BASIC HELIX-LOOP-HELIX POD1...
REFERENCES

Development of the mouse lung initiates on day 9.5 postcoitum from the laryngotracheal groove and involves mesenchymal-epithelial interactions, in particular, those between the splanchnic mesoderm and epithelial cells (derived from foregut endoderm) that induce cellular proliferation, migration, and differentiation, resulting in branching morphogenesis. This developmental process mediates formation of the pulmonary bronchiole tree and integrates a terminal alveolar region with an extensive endothelial capillary bed, which facilitates efficient gas exchange with the circulatory system. The major function of the mesenchymal-epithelial signaling is to potentiate the activity or expression of cell type-specific transcription factors in the developing lung, which, in turn, cooperatively bind to distinct promoter regions and activate target gene expression. In this review, we focus on the role of transcription factors in lung morphogenesis and the maintenance of differentiated gene expression. These lung transcription factors include forkhead box A2 [also known as hepatocyte nuclear factor (HNF)-3beta ], HNF-3/forkhead homolog (HFH)-8 [also known as FoxF1 or forkhead-related activator-1], HNF-3/forkhead homolog-4 (also known as FoxJ1), thyroid transcription factor-1 (Nkx2.1), and homeodomain box A5 transcription factors, the zinc finger Gli (mouse homologs of the Drosophila cubitus interruptus) and GATA transcription factors, and the basic helix-loop-helix Pod1 transcription factor. We summarize the phenotypes of transgenic and knockout mouse models, which define important functions of these transcription factors in cellular differentiation and lung branching morphogenesis.

winged helix/forkhead box deoxyribonucleic acid binding domain; hepatocyte nuclear factor-3/forkhead homolog; homeodomain box; Nkx2.1; GATA; Gli; Pod1


    INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
IDENTIFICATION OF HNF-3 IN...
EXPRESSION OF FORKHEAD BOX...
MESENCHYMAL EXPRESSION OF HFH-8...
THE FOX TRANSCRIPTION FACTOR...
EXPRESSION OF FKH6 (FOXL1)...
EXPRESSION OF HFH-11B (FOXM1B)...
THE HOMEOBOX TRANSCRIPTION...
HOX TRANSCRIPTION FACTORS IN...
ROLE OF THE ZINC...
CUBITUS INTERRUPTUS GLI...
THE BASIC HELIX-LOOP-HELIX POD1...
REFERENCES

MOUSE LUNG BUD FORMATION INITIATES on day 9.5 postcoitum (pc) from the laryngotracheal groove and involves mesenchymal-epithelial cell interactions, which include paracrine growth factor stimulation that induces cellular proliferation, migration, and differentiation (74). Lung branching morphogenesis involves migration of foregut endoderm-derived epithelial cells into the surrounding splanchnic mesoderm, resulting in formation of the respiratory bronchioles and the terminal alveolar sacs, which integrate with the endothelial capillary bed (74). During mouse lung development, the pseudoglandular stage (days 9.5-16.6 pc) is characterized by formation of the bronchial and respiratory bronchiole tree, which is lined with undifferentiated epithelial cells juxtaposed to the splanchnic mesoderm (130). By day 12 pc of mouse lung development, branching of the bronchial buds gives rise to the left lung lobe and the four lobes of the right lung. There is extensive branching of the distal epithelium and mesenchyme during the canalicular stage (days 16.6-17.4 pc), resulting in formation of terminal sacs lined with epithelial cells integrating with the mesoderm-derived vasculature. The terminal sac stage [day 17.5 to postnatal day (PD) 5] of lung development is characterized by a coordinated increase in terminal sac formation and vasculogenesis in conjunction with the differentiation of alveolar epithelial type I and II cells. The alveolar stage (PD5 to PD30) of postnatal lung development features maturation of the terminal respiratory sacs into alveolar ducts and sacs. At the end of this developmental process, the mature respiratory system is lined with epithelial cells possessing distinct pulmonary functions, which vary in their distribution from the proximal to distal airway (130). Squamous epithelial cells line the larynx, and the upper airways are populated by a mixture of ciliated columnar and mucus-secreting goblet cells with foci of pulmonary neuroendocrine cells, whereas Clara cells predominate in the lower airways. The distal alveolar sacs are populated with surfactant protein (SP) A- and SP-C-secreting type II epithelial cells and type I epithelial cells that form tight junctions with the pulmonary endothelial cells, facilitating gas exchange with the circulatory system.

Branching morphogenesis of the lung involves mesenchymal-epithelial signaling that induces cellular proliferation, migration, and subsequent transcriptional activation of lung-specific genes. The lung mesenchyme possesses growth factor receptors, which respond to protein ligands secreted by the adjacent endoderm or epithelial cells. Sonic hedgehog (Shh)-deficient [(-/-)] mice exhibit fusion of the tracheoesophageal tube, loss of asymmetry of the lung (appears as one lobe), and diminished expansion of the alveolar region (69). Activation of the Gli transcription factors through the Shh signaling transduction pathway plays an important role in lung morphogenesis (38, 86, 93, 110, 136). Transgenic mouse studies in which the SP-C gene-regulatory region was used to increase distal epithelial cell expression of either Shh (6) or keratinocyte growth factor (119) resulted in overproliferation of lung mesenchyme, leading to defects in branching morphogenesis. Appropriate expression of bone morphogenetic protein-4 (BMP-4) (8, 132), hepatocyte growth factor (HGF) (87), and fibroblast growth factor (FGF)-10 (7) is critical in regulating pulmonary epithelial cell proliferation, migration, and branching morphogenesis of the lung. Fgf10(-/-) mice die immediately after birth due to disruption of pulmonary branching morphogenesis, and this phenotype is coincident with severe reductions in the expression of Shh and BMP-4 (lung endoderm) and mesenchymally derived Wnt2 (114). In combination with in vitro lung culture studies (114, 131), analysis of Fgf10(-/-) mice revealed that FGF-10 is involved in the induction of Shh, BMP-4, and Wnt2 signaling molecules, all of which are essential for lung development. Moreover, transgenic mouse studies (95, 125) have provided further evidence that the FGF signaling pathway is critical for airway branching and pulmonary epithelial differentiation. These studies identified several growth factors and signaling molecules that play important roles in lung morphogenesis during mouse embryonic development.

Vascular endothelial growth factor (VEGF) is expressed in the endoderm or ectoderm and acts in a paracrine fashion on adjacent mesoderm tissue to induce proliferation, cell migration, and angioblast differentiation toward endothelial cell lineage (17, 105). This developmental process is important for the formation of new blood vessels de novo (vasculogenesis) or from preexisting vessels (angiogenesis). Targeted disruption of the VEGF gene produces mutant embryos that display impaired blood island formation and delayed endothelial cell differentiation, leading to abnormal blood vessel development (20, 35). VEGF is the ligand for fms-like receptor tyrosine kinase [Flt-1; VEGF receptor-1 (VEGFR-1)] and receptor tyrosine kinase Flk-1 (VEGFR-2), which are expressed in the primitive endothelium derived from mesoderm (105). Ablation of the Flk1 gene inhibits vasculogenesis and formation of angioblast cells in the blood islands (115), whereas disruption of the Flt1 gene allows the formation of angioblasts but inhibits their assembly into functional blood vessels (36). Other receptor tyrosine kinases involved in blood vessel formation include the Tie1 and Tie2 (TEK) genes, which are expressed in the lateral and extraembryonic mesoderm of the developing embryo (34, 58). Mice containing targeted Tie1 gene disruption have defects in endothelial cell function and blood vessel formation, leading to pulmonary edema and hemorrhage (99, 112). Targeted ablation of the Tie2 (TEK) gene leads to defects in endothelial cell proliferation and migration, which cause inhibition of angiogenesis (112). Ligand stimulation of the endothelial receptors Tie-1 and Tie-2 therefore plays an important role in vascular remodeling (140). In the lung, overexpression of VEGF in the respiratory epithelium stimulated vasculogenesis in transgenic mouse lungs, but its elevated expression resulted in aberrant vessel formation and increased expression of Flk-1 and Tie-1 (146). Identification of lung mesenchymal transcription factors mediating expression of these receptor tyrosine kinases will therefore provide insights regarding pulmonary vasculogenesis and angiogenesis during embryonic development or after acute lung injury.

The major function of these signaling pathways is to potentiate the activity or expression of mesenchyme- or endoderm-specific transcription factors in the developing lung. These, in turn, bind cooperatively to distinct promoter regions and activate target gene expression. The dynamic changes in gene expression during lung development are critical to mediate lung morphogenesis, which involves extensive cellular proliferation, migration, and establishment of appropriate positioning of respiratory epithelial cells with the mesenchyme-derived endothelial cells. The molecular events involved in the process of lung morphogenesis have been reviewed recently by Warburton et al. (130). We focus our review on the role of transcription factors in lung morphogenesis and the maintenance of differentiated gene expression. We include forkhead box (Fox) A2 [FoxA2; hepatocyte nuclear factor (HNF)-3beta ], FoxF1 [HNF-3/forkhead homolog (HFH)-8; forkhead-related activator (FREAC)-1], and FoxJ1 (HFH-4) transcription factors; Nkx2.1 homeodomain or thyroid transcription factor (TTF)-1; homeodomain box (Hox) A5; the zinc finger Gli transcription factors (related to Drosophila cubitus interruptus); the basic helix-loop-helix (bHLH) Pod1; and GATA transcription factors. We summarize the phenotypes of transgenic and knockout mouse models, which define important functions of these transcription factors in mouse lung development.


    IDENTIFICATION OF HNF-3 IN REGULATING LUNG EPITHELIAL CELL-SPECIFIC TRANSCRIPTION
TOP
ABSTRACT
INTRODUCTION
IDENTIFICATION OF HNF-3 IN...
EXPRESSION OF FORKHEAD BOX...
MESENCHYMAL EXPRESSION OF HFH-8...
THE FOX TRANSCRIPTION FACTOR...
EXPRESSION OF FKH6 (FOXL1)...
EXPRESSION OF HFH-11B (FOXM1B)...
THE HOMEOBOX TRANSCRIPTION...
HOX TRANSCRIPTION FACTORS IN...
ROLE OF THE ZINC...
CUBITUS INTERRUPTUS GLI...
THE BASIC HELIX-LOOP-HELIX POD1...
REFERENCES

Functional analysis of the regulatory regions of hepatocyte-specific genes served as an important model system and determined that hepatocyte-specific gene transcription is dependent on the recognition of multiple DNA binding sites by distinct families of HNFs as well as by widely distributed transcription factors (21). These studies also revealed that detectable promoter activity required synergistic interactions among multiple HNF proteins and that this requirement plays an important role in maintaining cell-specific gene expression (22, 27-32, 37, 45, 82, 91, 107, 108). The HNF-3alpha , -3beta , and -3gamma proteins were originally identified as mediating transcription of hepatocyte-specific genes (28, 64, 65) and sharing homology in the winged helix/forkhead DNA binding domain (25, 73). The HNF-3alpha and HNF-3beta proteins share 93% amino acid homology in the winged helix DNA binding domain, bind to the same DNA consensus sequences (Fig. 1), and are potent transcriptional activators (64, 65, 89). The HNF-3 proteins possess a conserved NH2-terminal transcriptional activation domain that is critical for mediating protein interactions with other HNF transcription factors (41). An essential HNF-3 transcriptional activation domain resides within the COOH-terminal 100-amino acid residues (Fig. 1), which contain the functionally important conserved region II and III sequences (90, 100). Interestingly, a recent study (129) demonstrated that the region II sequences in the HNF-3 COOH-terminal domain can associate with the human homolog of the Drosophila Groucho transcriptional repressor proteins, which suggests the possibility that HNF-3 proteins may also function to inhibit transcription in cell types expressing Groucho proteins. Furthermore, functional analysis of the HNF-3beta protein demonstrated that the nuclear localization function resides within the winged helix DNA binding domain (100), which is a general feature displayed by other forkhead transcription factors (9, 43).


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Fig. 1.   Functional protein domains (A) and DNA binding consensus sequences (B and C) of the lung forkhead box (Fox) transcription factors. A: schematic diagram of the forkhead/winged helix DNA binding domain [percent amino acid homology; region I (magenta)] of the 5 lung Fox transcription factors that contain the nuclear localization signal (NLS) (100). Indicated on the hepatocyte nuclear factor (HNF)-3alpha (also known as FoxA1) and HNF-3beta (also known as FoxA2) proteins are their conserved NH2-terminal [region IV/V (purple)] and COOH-terminal [conserved region II (red) and region III (orange)] transcriptional activation domains (TADs) (90, 100). Also shown are the TADs (various colors) for HNF-3/forkhead homolog (HFH)-8 [also known as forkhead-related activator (FREAC-1) and FoxF1], HFH-4 (also known as FoxJ1), and HFH-11B (also known as FoxM1B and Trident) proteins (43, 44, 68, 71, 97, 143). Nos. at bottom, amino acid residues defining the functional protein domain. B: amino acid sequence alignment of HNF-3alpha compared with HNF-3beta , HFH-4, HFH-8, and HFH-11B winged helix/forkhead DNA binding domains, which are presented in decreasing order of homology (percentages on right) (26). Orange dots, conserved amino acid residues; orange letters, conservative changes; green letters, nonconservative changes. The positions of the helices (blue), wing structures (brown), the beta -sheets (S1-S3; orange), and turn (T') are indicated on the sequence. Also indicated is the 20-amino acid region involved in dictating the DNA binding specificity region. Structure-function studies with chimeric winged helix proteins demonstrated that swapping this 20-amino acid region between 2 winged helix proteins is capable of altering DNA binding specificity (89). C: DNA binding consensus sequences for the lung Fox transcription factors. The consensus DNA binding sequence for each of the Fox proteins was determined by PCR-mediated DNA binding site selection with recombinant glutathione S-transferase winged helix protein with a partially degenerate oligonucleotide as previously described (68, 89, 97, 98). V is not T; W is A or T; R is G or A; Y is T or C; N is any nucleotide; D is not C; H is not G.

Functional analysis of the regulatory region of lung-specific genes also demonstrated that normal promoter activity required synergistic interaction of multiple cell-specific transcription factors in conjunction with inducible and widely expressed transcription factors (10, 14, 15, 113, 122). These promoter studies (10, 11, 14, 42, 49, 113) demonstrated an important role for HNF-3alpha and HNF-3beta proteins in regulating transcription of SP and Clara cell secretory protein (CCSP) genes required for bronchiolar and type II epithelial cell function (Table 1). A transfection study (108) demonstrated that Hnf3beta gene expression is stimulated by interferon (IFN)-gamma through promoter recognition by the IFN regulatory factor-1 protein (108). Subsequent CCSP promoter studies indicated that IFN-gamma induction of CCSP gene transcription involves promoter activation by the HNF-3beta and signal transducer and activator of transcription (STAT) proteins (70). Furthermore, HNF-3beta regulates promoter expression of the Nkx homeodomain transcription factor TTF-1 (47), which, in turn, regulates transcription of the SP genes (14, 19, 39, 139).

                              
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Table 1.   Expression patterns of lung transcription factors

Hnf3beta and Hnf3alpha genes display overlapping expression patterns during lung morphogenesis (Table 1), but Hnf3gamma is not expressed in the developing lung (83, 149). Because of the functional redundancies of the HNF-3beta and HNF-3alpha proteins in pulmonary epithelial cells, the function of these transcription factors during lung morphogenesis was not elucidated from analysis of mice containing targeted disruptions of the Hnf3 genes. The Hnf3alpha (-/-) mice display hypoglycemia due to reduced pancreatic expression of glucagon, but they exhibit normal lung development (50, 117). Likewise, the in vivo role of HNF-3beta in lung morphogenesis remains unknown because homozygous null Hnf3beta mouse embryos die in utero 9.5 days pc before lung morphogenesis (1, 134). Hnf3beta (-/-) embryos exhibit defects in the formation of the node, notochord, foregut endoderm, visceral endoderm, and neurotube (Table 2). With the availability of mice containing the LoxP-targeted HNF-3beta locus (123), the use of Cre recombinase technology for generating pulmonary epithelium-specific targeted disruption of the Hnf3beta gene will allow examination of the role of HNF-3beta in lung morphogenesis with either wild-type or Hnf3alpha (+/-) mouse backgrounds.

                              
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Table 2.   Phenotype of lung transcription factor homozygous null and TG mice

During lung development, HNF-3beta protein is expressed at higher levels in epithelial cells lining the proximal airways and at lower levels in the distal type 2 epithelial cells (149). Transgenic SP-C-Hnf3beta mice were generated that express high levels of HNF-3beta in the distal airway epithelial cells, which disrupted the normal decreasing gradient of HNF-3beta in these cells during lung development (148). In the most severe phenotype, the embryonic lungs consisted of primitive tubules, which were lined with undifferentiated columnar epithelial cells that intensely stained positive for the HNF-3beta protein (Table 2). Increased expression of HNF-3beta in the distal respiratory epithelium caused a striking inhibition in branching morphogenesis and vasculogenesis of the lung, which is coincident with diminished expression of E-cadherin and VEGF in these cells (148). These transgenic mouse studies indicated that maintaining precise levels of HNF-3beta is of critical importance in normal branching morphogenesis of the lung.


    EXPRESSION OF FORKHEAD BOX TRANSCRIPTION FACTORS IN THE LUNG
TOP
ABSTRACT
INTRODUCTION
IDENTIFICATION OF HNF-3 IN...
EXPRESSION OF FORKHEAD BOX...
MESENCHYMAL EXPRESSION OF HFH-8...
THE FOX TRANSCRIPTION FACTOR...
EXPRESSION OF FKH6 (FOXL1)...
EXPRESSION OF HFH-11B (FOXM1B)...
THE HOMEOBOX TRANSCRIPTION...
HOX TRANSCRIPTION FACTORS IN...
ROLE OF THE ZINC...
CUBITUS INTERRUPTUS GLI...
THE BASIC HELIX-LOOP-HELIX POD1...
REFERENCES

Rodent HNF-3 (28, 64, 65) and Drosophila homeotic forkhead proteins (133) were the first identified members of an extensive family of transcription factors that shares homology in the winged helix DNA binding domain (25). The HNF-3/winged helix/forkhead proteins are a growing family of transcription factors that play important roles in cellular proliferation and differentiation (55) and have recently been renamed as the forkhead box (Fox) family (51). With PCR amplification of rodent organ cDNA with primers made to conserved amino acid sequences in the winged helix DNA binding domain, a number of new Fox family members were isolated from a variety of different mouse tissues (26, 52, 98). Several Fox genes that are expressed in the mouse lung were isolated (Table 1), including HNF3/forkhead homolog-8 (Hfh8; also known as Freac1 or Foxf1), which is expressed in the mesenchyme of the developing and adult mouse lung (71, 97); forkhead 6 (Fkh6; also known as Foxl1), the expression of which is observed in embryonic lung mesenchyme (48); Hfh4 (Foxj1), which is expressed in the ciliated epithelial cells of the developing and adult lung (12, 18, 24, 126), and Hfh11 (Foxm1, Trident, Win), the expression of which is restricted to proliferating cells of the embryonic lung (143) and is also reactivated after lung injury (54).


    MESENCHYMAL EXPRESSION OF HFH-8 (FOXF1) IN DEVELOPING LUNG
TOP
ABSTRACT
INTRODUCTION
IDENTIFICATION OF HNF-3 IN...
EXPRESSION OF FORKHEAD BOX...
MESENCHYMAL EXPRESSION OF HFH-8...
THE FOX TRANSCRIPTION FACTOR...
EXPRESSION OF FKH6 (FOXL1)...
EXPRESSION OF HFH-11B (FOXM1B)...
THE HOMEOBOX TRANSCRIPTION...
HOX TRANSCRIPTION FACTORS IN...
ROLE OF THE ZINC...
CUBITUS INTERRUPTUS GLI...
THE BASIC HELIX-LOOP-HELIX POD1...
REFERENCES

To identify the cellular expression pattern of the HFH8 (Freac1 or Foxf1) gene during mouse embryonic development, in situ hybridization of mouse embryo paraffin sections was performed with 33P-labeled antisense HFH-8 RNA probe (97). After hybridization, stringent washes and autoradiography, dark-field microscopy was used to visualize HFH-8-expressing cells in the tissues (Fig. 2, B, D, F, H, and J). These studies demonstrate that HFH-8 expression initiates during mouse gastrulation on day 7 pc in the extraembryonic mesoderm, the allantois, and the lateral mesoderm that arises from the primitive streak region (See Table 1). Abundant HFH-8 expression continues in the lateral mesoderm-derived somatopleuric and splanchnopleuric mesoderm (Fig. 2, A and B), which contribute to endothelial cell formation in the embryo proper (92). At the onset of organogenesis at 9.5 days pc, HFH-8 expression is restricted to the splanchnic mesoderm contacting the embryonic gut and presumptive lung bud (Fig. 2, C and D), suggesting that it may participate in the mesenchymal-epithelial induction of lung and gut morphogenesis (71, 97). HFH-8 expression continues in lateral mesoderm-derived tissue throughout mouse development and includes the mesenchymal cells of the oral cavity, esophagus, trachea, lung, gut, dorsal aorta, and intersomitic arteries (Fig. 2, E-H) but not of the head (71, 97). In day 18.5 pc embryos, HFH-8 is restricted to the distal mesenchyme of the lung and the muscle layer of the bronchus, but its signals are absent in the epithelial cells and mesenchyme of large vessels (Fig. 2, I and J).


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Fig. 2.   HFH-8 expression patterns in developing mouse embryo as shown by in situ hybridization with 33P-labeled antisense HFH-8 RNA probe of sectioned paraffin-embedded 8 (A and B)-, 9.5 (C and D)-, 13.5 (E and F)-, 16 (G and H)-, and 18.5 (I and J)-day postcoitum mouse embryos. After hybridization, stringent washes, and autoradiography, dark-field microscopy (B, D, F, H, and J) was used to visualize HFH-8-expressing cells in the tissues. A and B: in transverse sections of 8-day postcoitum mouse embryos, HFH-8 was expressed in derivatives of the lateral and extraembryonic mesoderm. C and D: in transverse sections of 9.5-day postcoitum mouse embryos, HFH-8 was expressed in the splanchnic mesoderm (SM) juxtaposed to the lung bud [LB; derived from foregut (Fg) endoderm (en)]. HFH-8 expression was observed in splanchnopleure (Sp) and somatopleure (So) mesoderm near the dorsal aorta (DA) and in yolk sac mesoderm (YSM) and amnion (am). E and F: in sagittal sections of 13.5-day postcoitum mouse embryo, HFH-8 expression was restricted to mesenchyme derived from the lateral mesoderm. HFH-8 was expressed in the mesenchyme surrounding the incisors [upper incisors (UI)] and in the mesenchyme of the tongue (T), oropharynx (Op), epiglottis (Ep), esophagus (Es), trachea (Tr), DA, intersomitic arteries (IA), lung (Lu), stomach (S), and intestine (In). No hybridization is found in the heart (He), liver (L), or vasculature (V) of the brain. G and H: in sagittal sections of 16-day postcoitum mouse embryo, HFH-8 continued in the mesenchyme of the lung, stomach, and intestine. I and J: in 18.5-day embryonic mouse lung, HFH-8 expression was found in the mesenchyme of the alveoli and bronchus (Br). No HFH-8 hybridization signals were observed in the epithelial cells of the bronchioles (b) or in the mesenchyme of the arterioles (a). K, kidney; NT, neurotube; PC, peritoneal cavity; CC, costal cartilage. (A-H are reprinted from Mech Dev 69. Peterson RS, Lim L, He H, Overdier D, and Costa RH. The winged helix transcriptional activator HFH-8 is expressed in the mesoderm of the primitive streak stage of mouse embryos and its cellular derivatives, p. 53-69. Copyright 1997, with permission from Elsevier Science.)

In more recent studies, we generated a targeted disruption of the mouse Hfh8 gene in which the winged helix DNA binding domain was replaced by an in-frame insertion of a nuclear-localizing beta -galactosidase gene (Kalinichenko VV, Lim L, Whitsett JA, Clark J, and Costa RH, unpublished observations). Expression of the beta -galactosidase gene was under the control of the HFH-8 DNA-regulatory sequences, and thus staining for beta -galactosidase enzyme activity allowed identification of HFH-8-expressing cells. They were found to be colocalized with platelet endothelial cell adhesion molecule-1-positive alveolar endothelial cells and with alpha -smooth muscle actin-positive peribronchiolar smooth muscle cells, but pulmonary blood vessels lacked detectable HFH-8 staining (54). These expression studies with adult Hfh8(+/-) lungs demonstrate that HFH-8 expression is restricted to the alveolar endothelial cells and the smooth muscle surrounding the bronchioles. However, our immunohistochemical staining data cannot rule out the possibility that HFH-8 is also expressed in alveolar myofibroblasts. Consistent with the early expression pattern in the extraembryonic and lateral mesoderm-derived tissues, Hfh8(-/-) mice die in utero (Kalinichenko VV, Lim L, Whitsett JA, Clark J, and Costa RH, unpublished observations). Moreover, Hfh8(+/-) mice exhibit defects in lung morphogenesis and function, suggesting that wild-type levels of HFH-8 are necessary for normal lung development.

We determined the DNA binding consensus sequence of HFH-8 using recombinant HFH-8 protein and PCR-mediated DNA site selection (97). Identification of this DNA binding consensus sequence revealed that HFH-8 binding sites are present in the promoter regions of genes critical for lung morphogenesis, mesenchyme proliferation, mesenchymal-epithelial signaling, and angiogenesis or vasculogenesis (see Table 3 for potential Hfh8 target genes). The HFH-8 protein therefore potentially regulates mesenchymal expression of the platelet-derived growth factor receptors (118, 120), which are required for alveolar structure formation (16), and receptor tyrosine kinase Tie-1, VEGFR-1 (Flt-1), and vascular endothelial (VE)-cadherin, which are required for endothelial cell function and assembly of endothelial cells into functional blood vessels (36, 58, 99, 112, 127); HFH-8 binding sites were also found in the promoter regions of mesenchyme-signaling Hgf and Bmp4 genes, the expression of which is critical for lung morphogenesis (8, 87) and extracellular matrix protease genes (Table 3, urokinase-type plasminogen activator, matrix metalloproteinase-1, and collagenase), which are involved in cell migration or cellular repair from injury. Interestingly, HFH-8 may regulate expression of the lung mesenchymal transcription factors homeodomain Hoxa5 and Hoxb5 genes, and they share overlapping embryonic expression with HFH-8 in the mesenchyme of the distal tips of the developing lung (5, 13). Moreover, Hoxa5(-/-) mice show respiratory tract defects attributed to decreases in pulmonary epithelial cell expression of TTF-1, HNF-3beta and N-myc (5), suggesting that HFH-8 may also regulate mesenchyme-mediated lung epithelial cell development through regulation of the Hoxa5 gene.

                              
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Table 3.   Putative HFH-8 target genes in mesenchymal cells of lung and intestine

Functional analysis of the HFH-8 protein with cotransfection assays with the Hfh8-dependent reporter gene identified a cell type-specific activation domain (Fig. 1A) that resides in the COOH-terminal region of the protein (71, 97). Interestingly, this HFH-8 transcriptional activation domain also exhibits homology with FoxF2 (FREAC-2; Lun), a Fox transcription factor that is expressed in pulmonary epithelial cell lines and also shares amino acid identity with the HFH-8 winged helix DNA binding motif (44, 76). A second activation domain that included conserved regions II and III was shown to activate transcription in undifferentiated cell lines but did not function in differentiated lung cell lines (44, 71).

Cytokines stimulate the cell type-specific expression of the P-selectin gene, the expression of which mediates cell adhesion of leukocytes to the endothelium and their subsequent extravasation to the underlying injured tissue (135). Cotransfection studies suggest that HFH-8, which is constitutively expressed in alveolar endothelial cells and peribronchiolar smooth muscle cells, may participate in cell type-specific activation of P-selectin in response to cytokines (97). Moreover, HFH-8 potentially regulates expression of cytokine and chemokine genes that are involved in recruiting inflammatory cells, including interleukin-8, interleukin-1alpha , monocyte chemoattractant protein-1, and eotaxin (see Table 3).


    THE FOX TRANSCRIPTION FACTOR HFH-4 (FOXJ1) IS REQUIRED FOR DIFFERENTIATION OF CILIATED EPITHELIAL CELLS
TOP
ABSTRACT
INTRODUCTION
IDENTIFICATION OF HNF-3 IN...
EXPRESSION OF FORKHEAD BOX...
MESENCHYMAL EXPRESSION OF HFH-8...
THE FOX TRANSCRIPTION FACTOR...
EXPRESSION OF FKH6 (FOXL1)...
EXPRESSION OF HFH-11B (FOXM1B)...
THE HOMEOBOX TRANSCRIPTION...
HOX TRANSCRIPTION FACTORS IN...
ROLE OF THE ZINC...
CUBITUS INTERRUPTUS GLI...
THE BASIC HELIX-LOOP-HELIX POD1...
REFERENCES

An in situ hybridization study (40) demonstrated that HFH-4 (FoxJ1) initiated expression in the proximal bronchiolar epithelial cells of the mouse embryonic lung 15.5 days pc, before the appearance of ciliated epithelial cells. Expression of HFH-4 mRNA was also observed in the ependymal cells and choroid epithelia on day 11 pc, which is several days before detectable HFH-4 levels in the mouse embryonic lung (68). Later in lung development, immunohistochemical staining demonstrates that the HFH-4 protein colocalizes with beta -tubulin IV-positive ciliated epithelial cells of the proximal airways (bronchioles, bronchi, and trachea; see Table 1) (12, 126). HFH-4 protein levels were also observed in ciliated epithelial cells of the esophagus, nose paranasal sinuses, ovaries, testis, and developing kidneys and in the ependymal cells lining the spinal chord and ventricles of the brain (12, 94, 126). In the adult mouse, HFH-4 expression continues in the ciliated epithelial cells of the lung and respiratory system, in the choroid plexus, and in stage-specific spermatocytes of the testis.

Consistent with the role of HFH-4 in mediated formation of ciliated epithelial cells during mouse embryogenesis, Hfh4(-/-) mice lacked staining for left-right dynein protein and 9+2 microtubules (motile type of cilia) in proximal epithelial cells of the lung and in the ventricles of the brain (18, 24). The Hfh4(-/-) mice displayed perinatal lethality because they were deficient in ciliated epithelial cells lining the pulmonary bronchioles and ventricles, leading to defects in lung function and hydrocephalus (Table 2). HFH-4 is also transiently expressed in the monociliated cells of the node, which plays an important role in orchestrating gastrulation. Although cilia were present on the Hfh4-deficient node cells, HFH-4 expression is required for left-right asymmetry of the internal organs and Hfh4(-/-) mice exhibit randomized situs inversus (internal organs display either left or right asymmetry). These genetic studies underscore the importance of HFH-4 in mediating differentiation of the ciliated epithelial cell lineage and in left-right asymmetry decisions during embryonic development.

A transgenic mouse study (124) in which HFH-4 protein was ectopically expressed in the distal respiratory epithelial cells resulted in defects of lung branching morphogenesis. Moreover, the distal airways were lined with atypical cuboidal or columnar epithelial cells. In support of the role of HFH-4 in mediating differentiation of ciliated epithelial cells, the atypical columnar cells that expressed high levels of the Hfh4 transgene stained positive for beta -tubulin IV, a marker for ciliated epithelial cells (Table 2). Although these transgenic pulmonary epithelial cells still expressed the transcription factors TTF-1 and HNF-3beta , they no longer expressed nonciliated epithelial marker genes including SP-C, SP-B, and CCSP. Ectopic expression of HFH-4 in the developing mouse lung therefore promoted differentiation toward the ciliated epithelial cellular lineage and inhibited expression of nonciliated epithelial marker genes.

HFH-4 protein is a potent transcriptional activator, with two activation domains at the NH2 terminus and COOH terminus of the protein (Fig. 1), and deletion of the conserved region II sequences caused a 25% reduction in transcriptional activity (68). HFH-4 binds to a consensus DNA binding sequence that is distinct from other Fox transcription factors (Fig. 1) in that it prefers guanine residues instead of purines in the core sequence and is less tolerant of nucleotide changes at the 3'-end of the binding site (68). It is interesting to note that although different Fox transcription factors bind to a similar core consensus sequence, slight nucleotide changes either 3' or 5' to this core sequence can alter binding specificity between different forkhead family members (89). Although the Fox proteins show strong amino acid identity in the recognition helix (helix 3), each transcription factor is capable of interacting with distinct DNA binding sites (Fig. 1). Structure-function studies with chimeric winged helix recombinant proteins demonstrated that a 20-amino acid region adjacent to the recognition helix can alter DNA binding specificity (see Fig. 1B), and these amino acid sequences are the most divergent within the winged helix DNA binding domain (89). Moreover, nuclear magnetic resonance structure analysis of the HFH-2 winged helix domain demonstrates that this DNA specificity region is able to fold into a fourth helical structure and functions to reposition the recognition helix into the DNA major groove (73).


    EXPRESSION OF FKH6 (FOXL1) TRANSCRIPTION FACTOR IN THE LUNG
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During mouse embryogenesis, Fkh6 expression overlaps with that of HFH-8 in the mesenchyme of the developing lung, stomach, gut, tongue, and teeth (48). The expression pattern of Fkh6 differs from HFH-8 in that it is also expressed in the mesenchyme of the kidney, temporal bones, nasal cavity, and otic and optic capsules. In adult mice, Fkh6 expression is extinguished in the lung, but its expression continues in the kidney, stomach, and small and large intestines. Despite the Fkh6 expression pattern in developing lung mesenchyme, the Fkh6(-/-) mice exhibit no defects in lung morphogenesis or function (53). Fkh6(-/-) mice die postnatally at 1 mo because of defects in the intestinal villus or crypt structures resulting from diminished mesenchymal expression of transforming growth factor-beta /activin family members (BMP-2 and BMP-4).


    EXPRESSION OF HFH-11B (FOXM1B) IS INDUCED AFTER ADULT LUNG INJURY
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The human Fox transcription factor HFH-11B (also known as Trident and FoxM1b) is a proliferation-specific transcription factor that shares 39% amino acid homology with the HNF-3 winged helix DNA binding domain (59, 141, 143). HFH-11B contains a potent COOH-terminal transcriptional activation domain that possesses several phosphorylation sites for M phase-specific kinases as well as proline-glutamic acid-serine-threonine (PEST) sequences (Fig. 1A) that mediate rapid protein degradation (59, 141, 143). HFH-11B is expressed in proliferating embryonic cells (including the lung), but its levels diminish postnatally during terminal differentiation (59, 143). HFH-11 expression continues in proliferating cells of adult tissue, primarily in the thymus, testis, small intestine, and colon (59, 143). Although HFH-11 expression is markedly induced during cellular proliferation, its promoter region displays only a marginal fourfold stimulation in response to serum, suggesting that increased HFH-11 mRNA stability also plays a role in its increased levels during proliferation (60, 143). Furthermore, HFH-11B function is regulated by nuclear translocation because transgenic HFH-11B protein remains cytoplasmic in quiescent liver and proliferative signals induce HFH-11B nuclear localization (142).

HFH-11 expression is essential for normal embryonic development as evidenced by the perinatal lethal phenotype exhibited by Hfh11/Trident(-/-) mice (61). Consistent with a role in mediating cell cycle progression, Hfh11/Trident-deficient embryos display an abnormal polyploid phenotype in embryonic hepatocytes and cardiomyocytes (day 13 pc), suggesting that HFH-11 expression is required to link DNA replication with mitosis (61). Reactivation of hepatic HFH-11B levels during liver regeneration occurs at the G1/S transition of the cell cycle, and its levels remain elevated throughout the period of proliferation (143). A liver regeneration study with transgenic mice (142) that prematurely expressed hepatic levels of HFH-11B revealed that the mice displayed an 8-h acceleration of hepatocyte entry into the S phase, resulting from earlier expression of cell cycle-regulatory genes.

Expression of HFH-11B is also reactivated by proliferative signals in the adult rat lung after intratracheal administration of keratinocyte growth factor (143). A more recent mouse lung injury study (54) has demonstrated that butylated hydroxytoluene (BHT) lung injury also reactivates expression of HFH-11B in epithelial and mesenchymal cells during the period of lung replication and repair (54). In a manner similar to that described for liver regeneration, this study determined that BHT-mediated lung injury stimulates expression of the HFH-11B transcription factor, suggesting that HFH-11B participates in cellular proliferation during lung injury repair. In the same BHT lung injury model, epithelial expression of HNF-3beta remained unchanged, whereas a 65% reduction in HFH-8 mRNA levels was observed during the period of mesenchymal cell proliferation repair (54).


    THE HOMEOBOX TRANSCRIPTION FACTOR NKX 2.1 (TTF-1) IS REQUIRED FOR LUNG MORPHOGENESIS
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The Nkx homeodomain transcription factor TTF-1 (also known as Nkx2.1 and thyroid-specific enhancer-binding protein) is expressed in the endoderm-derived epithelial cells of the presumptive and developing lungs and thyroid glands as well as in the embryonic diencephalon (39, 67). Immunohistochemical staining of developing mouse lung reveals TTF-1 staining in the proximal and distal airway epithelia and, at later stages of lung development, in the distal alveolar epithelial cells (149). Functional analysis of promoter and enhancer regions of the SP, T1alpha , and CCSP genes has implicated TTF-1 as critical for their transcriptional activation (14, 19, 39, 103, 137, 139, 147). Interestingly, cotransfection assays have demonstrated that TTF-1 promoter activity is stimulated by both the HNF-3beta (47) and GATA-6 (116) transcription factors, which may play an important role in stimulating Ttf1 gene expression during lung morphogenesis.

Consistent with the role of TTF-1 in lung development, Ttf1(-/-) mice display severe impairment in branching morphogenesis of the lung and in development of the thymus and pituitary glands (56). They also exhibit pronounced defects in ventral forebrain formation. The Ttf1-deficient lungs develop only into the main stem bronchi and lack development of the distal alveolar region, suggesting that their formation is arrested in the early pseudoglandular stage of lung development (56, 75). These Ttf1-deficient pulmonary epithelial cells fail to express nonciliated marker genes, including differentiated SP-B, SP-C, and CCSP (Table 2), and display reduced BMP-4 levels, which may contribute to the defect in lung branching morphogenesis (75). More recent examination of Ttf1(-/-) mice demonstrated that they lacked formation of septa between the trachea and the esophagus, leading to a common tracheoesophageal tube connecting the pharynx with the stomach (75). Furthermore, the developmentally arrested Ttf1-deficient lungs are connected to the atypical tracheoesophageal tube through the bronchi, which resembles the human pathological phenotype termed the tracheoesophageal fistula (75). This inhibition in tracheoesophageal septum formation is similar to that observed with the cubitus interruptus Gli2(-/-) mouse in a heterozygous Gli3 background (86) and the Shh(-/-) mice (69). These studies indicate the importance of TTF-1 in the development of the lungs and the respiratory system.


    HOX TRANSCRIPTION FACTORS IN LUNG MORPHOGENESIS
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A number of distinct Hox transcription factors are expressed in the presumptive lung during mouse embryogenesis, and their expression levels decrease as the mouse embryo reaches gestation (5, 13, 128). The Hox genes share homology in the helix-turn-helix motif but vary among family members in their ability to bind to DNA as either a monomer or dimer (23, 72). The Hoxb3 and Hoxb4 genes are expressed in the mesenchyme of the trachea, bronchi, and distal lung, whereas Hoxa5, Hoxb2, and Hoxb5 are restricted to the distal lung mesenchyme, suggesting a role in branching morphogenesis (Table 1). Consistent with an important role in mesenchymal-epithelial interactions, the Hoxa5(-/-) mice display improper tracheal formation and impaired lung branching morphogenesis, leading to tracheal occlusions, diminished surfactant expression, and thickening of alveolar walls (5). Loss of mesenchymal expression of the Hoxa5 gene caused a disruption in mesenchymal-epithelial signaling, leading to decreases in TTF-1, HNF-3beta , and N-myc expression in the pulmonary epithelial cells (Table 2). Future mouse gene targeting studies will allow determination of the role of the Hox genes in branching morphogenesis and mesenchymal-epithelial signaling during lung development.


    ROLE OF THE ZINC FINGER GATA TRANSCRIPTION FACTORS IN LUNG MORPHOGENESIS
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The GATA transcription factors were first identified as regulating hematopoietic genes and share homology in their DNA binding domains that contain two zinc finger motifs (reviewed in Refs. 78, 88). In situ hybridization studies (3, 66) demonstrated that GATA-4 is expressed in the heart, gut endoderm, intestinal epithelium, liver, testis, and ovaries. GATA-4 expression is induced by retinoic acid differentiation of F9 cells into visceral or parietal endoderm and in embryoid body-induced differentiation of embryonic stem cells into visceral endoderm (3). Consistent with this embryonic expression pattern, Gata4(-/-) embryos die shortly after gastrulation and exhibit defects in heart morphogenesis and in foregut endoderm and visceral endoderm formation (63, 79). This phenotype suggests that GATA-4 expression is required for foregut endoderm specification and may play an early role in the development of foregut endoderm-derived organs (145). Future studies involving tetraploid rescue of the visceral endoderm defect will allow examination of the role of GATA-4 in gut endoderm morphogenesis and possibly in lung morphogenesis.

The GATA-5 and GATA-6 transcription factors display nonoverlapping expression patterns in the developing lung; GATA-6 expression is restricted to the bronchiolar epithelial cells of the lung (84), whereas GATA-5 is expressed in the smooth muscle cells of the large airways (85). The GATA transcription factors display similar expression patterns in developing heart, allantois, and gut epithelial cells, but at later stages of heart development, GATA-5 levels diminish. Their expression patterns differ in that GATA-6 expression is found in the primitive streak mesoderm and in Reichert's membrane (Table 1). Targeted disruption of the Gata5 gene leads to vaginal and uterine defects in females, but the mice display no defects in lung morphogenesis (81). Gata6(-/-) embryos die during gastrulation from defects in extraembryonic tissue, and, therefore, its role in lung development remains unknown. Gata6 may likely play a role in lung morphogenesis given the fact that it regulates expression of TTF-1 (116), which is essential for lung formation. Future experiments with Cre/LoxP technology will allow cell type-specific ablation of the Gata6 gene and determination of its role in lung morphogenesis and function.


    CUBITUS INTERRUPTUS GLI TRANSCRIPTION FACTORS IN LUNG MORPHOGENESIS
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The zinc finger Gli transcription factors are homologs of the Drosophila segment polarity gene cubitus interruptus and mediate transcriptional induction in response to Shh signaling (38, 46). Gli3XtJ/Gli3XtJ mice, a naturally occurring mouse mutation in the Gli3 gene, exhibit defects in the right medial, right caudal, and accessory lobes of the lungs (38). Targeted disruption of the Gli2 gene results in a perinatal lethal phenotype with diminished lung proliferation and branching, leading to fusion of the four right lung lobes into one lobe (77, 86). This lung phenotype is coincident with diminished expression of the Shh receptor Patch and the isoform Gli1 (Table 2). Gli2(-/-) mice also display severe skeletal and neuronal defects, including hypoplastic trachea and esophagus (77). By contrast, no defects were observed in the transcriptionally inactive Gli1(zfd/zfd) mouse mutation, which deleted the exons encoding the zinc finger DNA binding domain (zfd) (93). Interestingly, Gli1(zfd/zfd),Gli2(zfd/+) mice, but not Gli1(zfd/zfd),Gli3(zfd/+) mice, die soon after birth and have multiple defects, including development of smaller lungs, suggesting that the Gli1 and Gli2 genes have redundant functions (Table 2). Gli1(zfd/zfd), Gli2(zfd/zfd) double-mutant mice have more severe lung defects that are similar to those found with the Shh(-/-) mice in which the lung develops but displays inhibition of branching morphogenesis (69).

A more severe lung defect is observed with the Gli2 gene deficiency analyzed in a Gli3 heterozygous background (86). Gli2(-/-),Gli3(+/-) embryonic mouse lungs are more hypoplastic, and the right and left lobes fail to separate (86). These mice have defective tracheoesophageal septum formation and possess a single tracheoesophageal tube, which connects the pharynx with the stomach, resembling the phenotype observed with either the Shh(-/-) (69) or Ttf1 (Nkx 2.1)(-/-) mice (75). The most severe phenotype is exhibited by the Gli3(-/-),Gli2(-/-) mice, which display a complete absence of lung, trachea, and esophagus and smaller stomach, liver, and pancreas (86). Interestingly, the phenotype of Gli3(-/-),Gli2(-/-) mice is more severe than that in Shh(-/-) mice (69), suggesting that these Gli transcription factors are not only regulated by Shh but may also be controlled by other signal transduction pathways.


    THE BASIC HELIX-LOOP-HELIX POD1 TRANSCRIPTION FACTOR IN LUNG MORPHOGENESIS
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Pod1 is a bHLH transcription factor in which the helix-loop-helix domain mediates protein association, allowing formation of either homodimeric and heterodimeric proteins, which then interact with DNA though the basic amino acid region (80). Pod1 is abundantly expressed in the mesenchyme of developing organs of the mouse embryo, including the lung, kidney, gut, and heart and in glomerular visceral epithelial cells (podocytes) (101, 102). Pod1(-/-) mice exhibit a perinatal lethal phenotype, displaying hypoplastic lungs that lack development of the alveolar region and kidneys that are deficient in mature glomeruli (101). Although Pod1 is exclusively expressed in the mesenchyme and podocytes, major defects are observed in the adjacent epithelia and include abnormalities in epithelial cell differentiation and branching morphogenesis (Table 2). Pod1 therefore appears to be essential for regulating genes involved in mesenchymal-epithelial interactions, which are critical for the morphogenesis of the lung and kidney.


    ACKNOWLEDGEMENTS

We thank Pradip Raychaudhuri and Francisco Rausa for critically reading this review.


    FOOTNOTES

The work in our laboratory was supported National Heart, Lung, and Blood Institute Grant HL-62446; National Institute of Diabetes and Digestive and Kidney Diseases Grant DK-54687; and National Institute of General Medical Sciences Grant GM-43241.

Address for reprint requests and other correspondence: R. H. Costa, Dept. of Molecular Genetics (M/C 669), Univ. of Illinois at Chicago, College of Medicine, 900 S. Ashland Ave, Rm. 2220 MBRB, Chicago, IL 60607-7170 (E-mail: Robcosta{at}uic.edu).


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1.   Ang, SL, and Rossant J. HNF-3beta is essential for node and notochord formation in mouse development. Cell 78: 561-574, 1994[ISI][Medline].

2.   Ang, SL, Wierda A, Wong D, Stevens KA, Cascio S, Rossant J, and Zaret KS. The formation and maintenance of the definitive endoderm lineage in the mouse: involvement of HNF3/forkhead proteins. Development 119: 1301-1315, 1993[Abstract/Free Full Text].

3.   Arceci, RJ, King AA, Simon MC, Orkin SH, and Wilson DB. Mouse GATA-4: a retinoic acid-inducible GATA-binding transcription factor expressed in endodermally derived tissues and heart. Mol Cell Biol 13: 2235-2246, 1993[Abstract].

4.   Aubin, J, Chailler P, Menard D, and Jeannotte L. Loss of Hoxa5 gene function in mice perturbs intestinal maturation. Am J Physiol Cell Physiol 277: C965-C973, 1999[Abstract/Free Full Text].

5.   Aubin, J, Lemieux M, Tremblay M, Berard J, and Jeannotte L. Early postnatal lethality in Hoxa-5 mutant mice is attributable to respiratory tract defects. Dev Biol 192: 432-445, 1997[ISI][Medline].

6.   Bellusci, S, Furuta Y, Rush MG, Henderson R, Winnier G, and Hogan BL. Involvement of sonic hedgehog (Shh) in mouse embryonic lung growth and morphogenesis. Development 124: 53-63, 1997[Abstract/Free Full Text].

7.   Bellusci, S, Grindley J, Emoto H, Itoh N, and Hogan BL. Fibroblast growth factor 10 (FGF10) and branching morphogenesis in the embryonic mouse lung. Development 124: 4867-4878, 1997[Abstract/Free Full Text].

8.   Bellusci, S, Henderson R, Winnier G, Oikawa T, and Hogan BLM Evidence from normal expression and targeted misexpression that bone morphogenetic protein-4 (Bmp-4) plays a role in mouse embryonic lung morphogenesis. Development 122: 1693-1702, 1996[Abstract/Free Full Text].

9.   Biggs, WH, III, Meisenhelder J, Hunter T, Cavenee WK, and Arden KC. Protein kinase B/Akt-mediated phosphorylation promotes nuclear exclusion of the winged helix transcription factor FKHR1. Proc Natl Acad Sci USA 96: 7421-7426, 1999[Abstract/Free Full Text].

10.   Bingle, CD, and Gitlin JD. Identification of hepatocyte nuclear factor-3 binding sites in the Clara cell secretory protein gene. Biochem J 295: 227-232, 1993[ISI][Medline].

11.   Bingle, CD, Hackett BP, Moxley M, Longmore W, and Gitlin JD. Role of hepatocyte nuclear factor-3alpha and hepatocyte nuclear factor-3beta in Clara cell secretory protein gene expression in the bronchiolar epithelium. Biochem J 308: 197-202, 1995[ISI][Medline].

12.   Blatt, EN, Yan XH, Wuerffel MK, Hamilos DL, and Brody SL. Forkhead transcription factor HFH-4 expression is temporally related to ciliogenesis. Am J Respir Cell Mol Biol 21: 168-176, 1999[Abstract/Free Full Text].

13.   Bogue, CW, Lou LJ, Vasavada H, Wilson CM, and Jacobs HC. Expression of Hoxb genes in the developing mouse foregut and lung. Am J Respir Cell Mol Biol 15: 163-171, 1996[Abstract].

14.   Bohinski, RJ, Di Lauro R, and Whitsett JA. The lung-specific surfactant protein B gene promoter is a target for thyroid transcription factor 1 and hepatocyte nuclear factor 3, indicating common factors for organ-specific gene expression along the foregut axis. Mol Cell Biol 14: 5671-5681, 1994[Abstract].

15.   Bohinski, RJ, Huffman JA, Whitsett JA, and Lattier DL. Cis-active elements controlling lung cell-specific expression of human pulmonary surfactant protein B gene. J Biol Chem 268: 11160-11166, 1993[Abstract/Free Full Text].

16.   Bostrom, H, Willetts K, Pekny M, Leveen P, Lindahl P, Hedstrand H, Pekna M, Hellstrom M, Gebre-Medhin S, Schalling M, Nilsson M, Kurland S, Tornell J, Heath JK, and Betsholtz C. PDGF-A signaling is a critical event in lung alveolar myofibroblast development and alveogenesis. Cell 85: 863-873, 1996[ISI][Medline].

17.   Breier, G, Albrecht U, Sterrer S, and Risau W. Expression of vascular endothelial growth factor during embryonic angiogenesis and endothelial cell differentiation. Development 114: 521-532, 1992[Abstract].

18.   Brody, SL, Yan XH, Wuerffel MK, Song SK, and Shapiro SD. Ciliogenesis and left-right axis defects in forkhead factor HFH-4-null mice. Am J Respir Cell Mol Biol 23: 45-51, 2000[Abstract/Free Full Text].

19.   Bruno, MD, Bohinski RJ, Huelsman KM, Whitsett JA, and Korfhagen TR. Lung cell-specific expression of the murine surfactant protein A (SP-A) gene is mediated by interactions between the SP-A promoter and thyroid transcription factor-1. J Biol Chem 270: 6531-6536, 1995[Abstract/Free Full Text].

20.   Carmeliet, P, Ferreira V, Breier G, Pollefeyt S, Kieckens L, Gertsenstein M, Fahrig M, Vandenhoeck A, Harpal K, Eberhardt C, Declercq C, Pawling J, Moons L, Collen D, Risau W, and Nagy A. Abnormal blood vessel development and lethality in embryos lacking a single VEGF allele. Nature 380: 435-439, 1996[ISI][Medline].

21.   Cereghini, S. Liver-enriched transcription factors and hepatocyte differentiation. FASEB J 10: 267-282, 1996[Abstract/Free Full Text].

22.   Cereghini, S, Raymondjean M, Carranca AG, Herbomel P, and Yaniv M. Factors involved in control of tissue-specific expression of albumin gene. Cell 50: 627-638, 1987[ISI][Medline].

23.   Chariot, A, Gielen J, Merville MP, and Bours V. The homeodomain-containing proteins: an update on their interacting partners. Biochem Pharmacol 58: 1851-1857, 1999[ISI][Medline].

24.   Chen, J, Knowles HJ, Hebert JL, and Hackett BP. Mutation of the mouse hepatocyte nuclear factor/forkhead homologue 4 gene results in an absence of cilia and random left-right asymmetry. J Clin Invest 102: 1077-1082, 1998[Abstract/Free Full Text].

25.   Clark, KL, Halay ED, Lai E, and Burley SK. Co-crystal structure of the HNF-3/fork head DNA-recognition motif resembles histone H5. Nature 364: 412-420, 1993[ISI][Medline].

26.   Clevidence, DE, Overdier DG, Tao W, Qian X, Pani L, Lai E, and Costa RH. Identification of nine tissue-specific transcription factors of the hepatocyte nuclear factor 3/forkhead DNA-binding-domain family. Proc Natl Acad Sci USA 90: 3948-3952, 1993[Abstract].

27.   Costa, RH, and Grayson DR. Site-directed mutagenesis of hepatocyte nuclear factor (HNF) binding sites in the mouse transthyretin (TTR) promoter reveal synergistic interactions with its enhancer region. Nucleic Acids Res 19: 4139-4145, 1991[Abstract].

28.   Costa, RH, Grayson DR, and Darnell JE, Jr. Multiple hepatocyte-enriched nuclear factors function in the regulation of transthyretin and alpha 1-antitrypsin genes. Mol Cell Biol 9: 1415-1425, 1989[ISI][Medline].

29.   Costa, RH, Grayson DR, Xanthopoulos KG, and Darnell J, Jr. A liver-specific DNA-binding protein recognizes multiple nucleotide sites in regulatory regions of transthyretin, alpha 1-antitrypsin, albumin, and simian virus 40 genes. Proc Natl Acad Sci USA 85: 3840-3844, 1988[Abstract].

30.   Courtois, G, Baumhueter S, and Crabtree GR. Purified hepatocyte nuclear factor 1 interacts with a family of hepatocyte-specific promoters. Proc Natl Acad Sci USA 85: 7937-7941, 1988[Abstract].

31.   Courtois, G, Morgan JG, Campbell LA, Fourel G, and Crabtree GR. Interaction of a liver-specific nuclear factor with the fibrinogen and alpha 1-antitrypsin promoters. Science 238: 688-692, 1987[ISI][Medline].

32.   DiPersio, CM, Jackson DA, and Zaret KS. The extracellular matrix coordinately modulates liver transcription factors and hepatocyte morphology. Mol Cell Biol 11: 4405-4414, 1991[ISI][Medline].

33.   Dufort, D, Schwartz L, Harpal K, and Rossant J. The transcription factor HNF3beta is required in visceral endoderm for normal primitive streak morphogenesis. Development 125: 3015-3025, 1998[Abstract/Free Full Text].

34.   Dumont, DJ, Fong GH, Puri MC, Gradwohl G, Alitalo K, and Breitman ML. Vascularization of the mouse embryo: a study of flk-1, tek, tie, and vascular endothelial growth factor expression during development. Dev Dyn 203: 80-92, 1995[ISI][Medline].

35.   Ferrara, N, Carver-Moore K, Chen H, Dowd M, Lu L, O'Shea KS, Powell-Braxton L, Hillan KJ, and Moore MW. Heterozygous embryonic lethality induced by targeted inactivation of the VEGF gene. Nature 380: 439-442, 1996[ISI][Medline].

36.   Fong, GH, Rossant J, Gertsenstein M, and Breitman ML. Role of the Flt-1 receptor tyrosine kinase in regulating the assembly of vascular endothelium. Nature 376: 66-70, 1995[ISI][Medline].

37.   Friedman, AD, Landschulz WH, and McKnight SL. CCAAT/enhancer binding protein activates the promoter of the serum albumin gene in cultured hepatoma cells. Genes Dev 3: 1314-1322, 1989[Abstract].

38.   Grindley, JC, Bellusci S, Perkins D, and Hogan BL. Evidence for the involvement of the Gli gene family in embryonic mouse lung development. Dev Biol 188: 337-348, 1997[ISI][Medline].

39.   Guazzi, S, Price M, Felice MD, Damante G, Mattei M, and Lauro RD. Thyroid nuclear factor 1 (TTF-1) contains a homeodomain and displays a novel DNA binding specificity. EMBO J 9: 3631-3639, 1990[Abstract].

40.   Hackett, BP, Brody SL, Liang M, Zeitz ID, Bruns LA, and Gitlin JD. Primary structure of hepatocyte nuclear factor/forkhead homologue 4 and characterization of gene expression in the developing respiratory and reproductive epithelium. Proc Natl Acad Sci USA 92: 4249-4253, 1995[Abstract].

41.   Harnish, DC, Malik S, Kilbourne E, Costa R, and Karathanasis SK. Control of apolipoprotein AI gene expression through synergistic interactions between hepatocyte nuclear factors 3 and 4. J Biol Chem 271: 13621-13628, 1996[Abstract/Free Full Text].

42.   He, Y, Crouch EC, Rust K, Spaite E, and Brody SL. Proximal promoter of the surfactant protein D (SP-D) gene: regulatory roles of AP-1, forkhead box, and GT-box binding proteins. J Biol Chem 27: 31051-31060, 2000.

43.   Hellqvist, M, Mahlapuu M, Blixt A, Enerback S, and Carlsson P. The human forkhead protein FREAC-2 contains two functionally redundant activation domains and interacts with TBP and TFIIB. J Biol Chem 273: 23335-23343, 1998[Abstract/Free Full Text].

44.   Hellqvist, M, Mahlapuu M, Samuelsson L, Enerback S, and Carlsson P. Differential activation of lung-specific genes by two forkhead proteins, FREAC-1 and FREAC-2. J Biol Chem 271: 4482-4490, 1996[Abstract/Free Full Text].

45.   Herbst, RS, Friedman N, Darnell JE, Jr, and Babiss LE. Positive and negative regulatory elements in the mouse albumin enhancer. Proc Natl Acad Sci USA 86: 1553-1557, 1989[Abstract].

46.   Hui, CC, Slusarski D, Platt KA, Holmgren R, and Joyner AL. Expression of three mouse homologs of the Drosophila segment polarity gene cubitus interruptus, Gli, Gli-2, and Gli-3, in ectoderm- and mesoderm-derived tissues suggests multiple roles during postimplantation development. Dev Biol 162: 402-413, 1994[ISI][Medline].

47.   Ikeda, K, Shaw-White JR, Wert SE, and Whitsett JA. Hepatocyte nuclear factor 3 activates transcription of thyroid transcription factor 1 in respiratory epithelial cells. Mol Cell Biol 16: 3626-3636, 1996[Abstract].

48.   Kaestner, KH, Bleckmann SC, Monaghan AP, Schlondorff J, Mincheva A, Lichter P, and Schutz G. Clustered arrangement of winged helix genes fkh-6 and MFH-1: possible implications for mesoderm development. Development 122: 1751-1758, 1996[Abstract/Free Full Text].

49.   Kaestner, KH, Hiemisch H, Luckow B, and Schutz G. The HNF-3 gene family of transcription factors in mice: gene structure, cDNA sequence, and mRNA distribution. Genomics 20: 377-385, 1994[ISI][Medline].

50.   Kaestner, KH, Katz J, Liu Y, Drucker DJ, and Schutz G. Inactivation of the winged helix transcription factor HNF3alpha affects glucose homeostasis and islet glucagon gene expression in vivo. Genes Dev 13: 495-504, 1999[Abstract/Free Full Text].

51.   Kaestner, KH, Knochel W, and Martinez DE. Unified nomenclature for the winged helix/forkhead transcription factors. Genes Dev 14: 142-146, 2000[Free Full Text].

52.   Kaestner, KH, Lee KH, Schlondorff J, Hiemisch H, Monaghan AP, and Schutz G. Six members of the mouse forkhead gene family are developmentally regulated. Proc Natl Acad Sci USA 90: 7628-7631, 1993[Abstract/Free Full Text].

53.   Kaestner, KH, Silberg DG, Traber PG, and Schutz G. The mesenchymal winged helix transcription factor Fkh6 is required for the control of gastrointestinal proliferation and differentiation. Genes Dev 11: 1583-1595, 1997[Abstract].

54.   Kalinichenko, VV, Lim L, Shin B, and Costa RH. Differential expression of the forkhead box transcription factors following butylated hydroxytoluene mouse lung injury. Am J Physiol Lung Cell Mol Physiol 280: L695-L704, 2001[Abstract/Free Full Text].

55.   Kaufmann, E, and Knochel W. Five years on the wings of fork head. Mech Dev 57: 3-20, 1996[ISI][Medline].

56.   Kimura, S, Hara Y, Pineau T, Fernandez-Salguero P, Fox CH, Ward JM, and Gonzalez FJ. The T/ebp null mouse: thyroid-specific enhancer-binding protein is essential for the organogenesis of the thyroid, lung, ventral forebrain, and pituitary. Genes Dev 10: 60-69, 1996[Abstract].

57.   Kopachik, W, Hayward SW, and Cunha GR. Expression of hepatocyte nuclear factor-3alpha in rat prostate, seminal vesicle, and bladder. Dev Dyn 211: 131-140, 1998[ISI][Medline].

58.   Korhonen, J, Polvi A, Partanen J, and Alitalo K. The mouse tie receptor tyrosine kinase gene: expression during embryonic angiogenesis. Oncogene 9: 395-403, 1994[ISI][Medline].

59.   Korver, W, Roose J, and Clevers H. The winged-helix transcription factor Trident is expressed in cycling cells. Nucleic Acids Res 25: 1715-1719, 1997[Abstract/Free Full Text].

60.   Korver, W, Roose J, Heinen K, Weghuis DO, de Bruijn D, van Kessel AG, and Clevers H. The human TRIDENT/HFH-11/FKHL16 gene: structure, localization, and promoter characterization. Genomics 46: 435-442, 1997[ISI][Medline].

61.   Korver, W, Schilham MW, Moerer P, van den Hoff MJ, Dam K, Lamers WH, Medema RH, and Clevers H. Uncoupling of S phase and mitosis in cardiomyocytes and hepatocytes lacking the winged-helix transcription factor trident. Curr Biol 8: 1327-1330, 1998[ISI][Medline].

62.   Koutsourakis, M, Langeveld A, Patient R, Beddington R, and Grosveld F. The transcription factor GATA6 is essential for early extraembryonic development. Development 126: 723-732, 1999[Abstract/Free Full Text].

63.   Kuo, CT, Morrisey EE, Anandappa R, Sigrist K, Lu MM, Parmacek MS, Soudais C, and Leiden JM. GATA4 transcription factor is required for ventral morphogenesis and heart tube formation. Genes Dev 11: 1048-1060, 1997[Abstract].

64.   Lai, E, Prezioso VR, Smith E, Litvin O, Costa RH, and Darnell JE, Jr. HNF-3A, a hepatocyte-enriched transcription factor of novel structure is regulated transcriptionally. Genes Dev 4: 1427-1436, 1990[Abstract].

65.   Lai, E, Prezioso VR, Tao WF, Chen WS, and Darnell JE, Jr. Hepatocyte nuclear factor 3alpha belongs to a gene family in mammals that is homologous to the Drosophila homeotic gene fork head. Genes Dev 5: 416-427, 1991[Abstract].

66.   Laverriere, AC, MacNeill C, Mueller C, Poelmann RE, Burch JB, and Evans T. GATA-4/5/6, a subfamily of three transcription factors transcribed in developing heart and gut. J Biol Chem 269: 23177-23184, 1994[Abstract/Free Full Text].

67.   Lazzaro, D, Price M, de Felice M, and Di Lauro R. The transcription factor TTF-1 is expressed at the onset of thyroid and lung morphogenesis and in restricted regions of the foetal brain. Development 113: 1093-1104, 1991[Abstract].

68.   Lim, L, Zhou H, and Costa RH. The winged helix transcription factor HFH-4 is expressed during choroid plexus epithelial development in the mouse embryo. Proc Natl Acad Sci USA 94: 3094-3099, 1997[Abstract/Free Full Text].

69.   Litingtung, Y, Lei L, Westphal H, and Chiang C. Sonic hedgehog is essential to foregut development. Nat Genet 20: 58-61, 1998[ISI][Medline].

70.   Magdaleno, SM, Wang G, Jackson KJ, Ray MK, Welty S, Costa RH, and DeMayo FJ. Interferon-gamma regulation of Clara cell gene expression: in vivo and in vitro. Am J Physiol Lung Cell Mol Physiol 272: L1142-L1151, 1997[Abstract/Free Full Text].

71.   Mahlapuu, M, Pelto-Huikko M, Aitola M, Enerback S, and Carlsson P. FREAC-1 contains a cell-type-specific transcriptional activation domain and is expressed in epithelial-mesenchymal interfaces. Dev Biol 202: 183-195, 1998[ISI][Medline]. [Corrigenda. Dev Biol 207, March 1999, p. 476.]

72.   Mann, RS. The specificity of homeotic gene function. Bioessays 17: 855-863, 1995[ISI][Medline].

73.   Marsden, I, Jin C, and Liao X. Structural changes in the region directly adjacent to the DNA-binding helix highlight a possible mechanism to explain the observed changes in the sequence-specific binding of winged helix proteins. J Mol Biol 278: 293-299, 1998[ISI][Medline].

74.   Minoo, P, and King RJ. Epithelial-mesenchymal interaction in lung development. Annu Rev Physiol 56: 13-45, 1994[ISI][Medline].

75.   Minoo, P, Su G, Drum H, Bringas P, and Kimura S. Defects in tracheoesophageal and lung morphogenesis in Nkx2.1(-/-) mouse embryos. Dev Biol 209: 60-71, 1999[ISI][Medline].

76.   Miura, N, Kakinuma H, Sato M, Aiba N, Terada K, and Sugiyama T. Mouse forkhead (winged helix) gene LUN encodes a transactivator that acts in the lung. Genomics 50: 346-356, 1998[ISI][Medline].

77.   Mo, R, Freer AM, Zinyk DL, Crackower MA, Michaud J, Heng HH, Chik KW, Shi XM, Tsui LC, Cheng SH, Joyner AL, and Hui C. Specific and redundant functions of Gli2 and Gli3 zinc finger genes in skeletal patterning and development. Development 124: 113-123, 1997[Abstract/Free Full Text].

78.   Molkentin, JD. The zinc finger-containing transcription factors GATA-4, -5, and -6: ubiquitously expressed regulators of tissue-specific gene expression. J Biol Chem 275: 38949-38952, 2000[Free Full Text].

79.   Molkentin, JD, Lin Q, Duncan SA, and Olson EN. Requirement of the transcription factor GATA4 for heart tube formation and ventral morphogenesis. Genes Dev 11: 1061-1072, 1997[Abstract].

80.   Molkentin, JD, and Olson EN. Combinatorial control of muscle development by basic helix-loop-helix and MADS-box transcription factors. Proc Natl Acad Sci USA 93: 9366-9373, 1996[Abstract/Free Full Text].

81.   Molkentin, JD, Tymitz KM, Richardson JA, and Olson EN. Abnormalities of the genitourinary tract in female mice lacking GATA5. Mol Cell Biol 20: 5256-5260, 2000[Abstract/Free Full Text].

82.   Monaci, P, Nicosia A, and Cortese R. Two different liver-specific factors stimulate in vitro transcription from the human alpha 1-antitrypsin promoter. EMBO J 7: 2075-2087, 1988[Abstract].

83.   Monaghan, AP, Kaestner KH, Grau E, and Schutz G. Postimplantation expression patterns indicate a role for the mouse forkhead/HNF-3 alpha , beta  and gamma  genes in determination of the definitive endoderm, chordamesoderm and neuroectoderm. Development 119: 567-578, 1993[Abstract/Free Full Text].

84.   Morrisey, EE, Ip HS, Lu MM, and Parmacek MS. GATA-6: a zinc finger transcription factor that is expressed in multiple cell lineages derived from lateral mesoderm. Dev Biol 177: 309-322, 1996[ISI][Medline].

85.   Morrisey, EE, Ip HS, Tang Z, Lu MM, and Parmacek MS. GATA-5: a transcriptional activator expressed in a novel temporally and spatially-restricted pattern during embryonic development. Dev Biol 183: 21-36, 1997[ISI][Medline].

86.   Motoyama, J, Liu J, Mo R, Ding Q, Post M, and Hui CC. Essential function of Gli2 and Gli3 in the formation of lung, trachea and oesophagus. Nat Genet 20: 54-57, 1998[ISI][Medline].

87.   Ohmichi, H, Koshimizu U, Matsumoto K, and Nakamura T. Hepatocyte growth factor (HGF) acts as a mesenchyme-derived morphogenic factor during fetal lung development. Development 125: 1315-1324, 1998[Abstract/Free Full Text].

88.   Orkin, SH, Shivdasani RA, Fujiwara Y, and McDevitt MA. Transcription factor GATA-1 in megakaryocyte development. Stem Cells 2: 79-83, 1998.

89.   Overdier, DG, Porcella A, and Costa RH. The DNA-binding specificity of the hepatocyte nuclear factor 3/forkhead domain is influenced by amino-acid residues adjacent to the recognition helix. Mol Cell Biol 14: 2755-2766, 1994[Abstract].

90.   Pani, L, Overdier DG, Porcella A, Qian X, Lai E, and Costa RH. Hepatocyte nuclear factor 3beta contains two transcriptional activation domains, one of which is novel and conserved with the Drosophila fork head protein. Mol Cell Biol 12: 3723-3732, 1992[Abstract].

91.   Pani, L, Qian XB, Clevidence D, and Costa RH. The restricted promoter activity of the liver transcription factor hepatocyte nuclear factor 3beta involves a cell-specific factor and positive autoactivation. Mol Cell Biol 12: 552-562, 1992[Abstract].

92.   Pardanaud, L, Luton D, Prigent M, Bourcheix LM, Catala M, and Dieterlen-Lievre F. Two distinct endothelial lineages in ontogeny, one of them related to hemopoiesis. Development 122: 1363-1371, 1996[Abstract/Free Full Text].

93.   Park, HL, Bai C, Platt KA, Matise MP, Beeghly A, Hui CC, Nakashima M, and Joyner AL. Mouse Gli1 mutants are viable but have defects in SHH signaling in combination with a Gli2 mutation. Development 127: 1593-1605, 2000[Abstract/Free Full Text].

94.   Pelletier, GJ, Brody SL, Liapis H, White RA, and Hackett BP. A human forkhead/winged-helix transcription factor expressed in developing pulmonary and renal epithelium. Am J Physiol Lung Cell Mol Physiol 274: L351-L359, 1998[Abstract/Free Full Text].

95.   Peters, K, Werner S, Liao X, Wert S, Whitsett J, and Williams L. Targeted expression of a dominant negative FGF receptor blocks branching morphogenesis and epithelial differentiation of the mouse lung. EMBO J 13: 3296-3301, 1994[Abstract].

96.   Peterson, RS, Clevidence DE, Ye H, and Costa RH. Hepatocyte nuclear factor-3alpha promoter regulation involves recognition by cell-specific factors, thyroid transcription factor-1 and autoactivation. Cell Growth Differ 8: 69-82, 1997[Abstract].

97.   Peterson, RS, Lim L, Ye H, Zhou H, Overdier DG, and Costa RH. The winged helix transcriptional activator HFH-8 is expressed in the mesoderm of the primitive streak stage of mouse embryos and its cellular derivatives. Mech Dev 69: 53-69, 1997[ISI][Medline].

98.   Pierrou, S, Hellqvist M, Samuelsson L, Enerback S, and Carlsson P. Cloning and characterization of seven human forkhead proteins: binding site specificity and DNA bending. EMBO J 13: 5002-5012, 1994[Abstract].

99.   Puri, MC, Rossant J, Alitalo K, Bernstein A, and Partanen J. The receptor tyrosine kinase TIE is required for integrity and survival of vascular endothelial cells. EMBO J 14: 5884-5891, 1995[Abstract].

100.   Qian, X, and Costa RH. Analysis of HNF-3beta protein domains required for transcriptional activation and nuclear targeting. Nucleic Acids Res 23: 1184-1191, 1995[Abstract].

101.   Quaggin, SE, Schwartz L, Cui S, Igarashi P, Deimling J, Post M, and Rossant J. The basic-helix-loop-helix protein pod1 is critically important for kidney and lung organogenesis. Development 126: 5771-5783, 1999[Abstract/Free Full Text].

102.   Quaggin, SE, Vanden Heuvel GB, and Igarash P. Pod-1, a mesoderm-specific basic-helix-loop-helix protein expressed in mesenchymal and glomerular epithelial cells in the developing kidney. Mech Dev 71: 37-48, 1998[ISI][Medline].

103.   Ramirez, MI, Rishi AK, Cao YX, and Williams MC. TGT3, thyroid transcription factor I, and Sp1 elements regulate transcriptional activity of the 1.3-kilobase pair promoter of T1alpha, a lung alveolar type I cell gene. J Biol Chem 272: 26285-26294, 1997[Abstract/Free Full Text].

104.   Rausa, F, Samadani U, Ye H, Lim L, Fletcher CF, Jenkins NA, Copeland NG, and Costa RH. The cut-homeodomain transcriptional activator HNF-6 is coexpressed with its target gene HNF-3beta in the developing murine liver and pancreas. Dev Biol 192: 228-246, 1997[ISI][Medline].

105.   Risau, W. Mechanisms of angiogenesis. Nature 386: 671-674, 1997[ISI][Medline].

106.   Ruiz i Altaba, A, Prezioso VR, Darnell JE, and Jessell TM. Sequential expression of HNF-3beta and HNF-3alpha by embryonic organizing centers: the dorsal lip/node, notochord and floor plate. Mech Dev 44: 91-108, 1993[ISI][Medline].

107.   Samadani, U, and Costa RH. The transcriptional activator hepatocyte nuclear factor six regulates liver gene expression. Mol Cell Biol 16: 6273-6284, 1996[Abstract].

108.   Samadani, U, Porcella A, Pani L, Johnson PF, Burch J, Pine R, and Costa RH. Cytokine regulation of the liver transcription factor HNF-3beta is mediated by the C/EBP family and interferon regulatory factor 1. Cell Growth Differ 6: 879-890, 1995[Abstract].

109.   Sasaki, H, and Hogan BL. Differential expression of multiple fork head related genes during gastrulation and axial pattern formation in the mouse embryo. Development 118: 47-59, 1993[Abstract/Free Full Text].

110.   Sasaki, H, Nishizaki Y, Hui C, Nakafuku M, and Kondoh H. Regulation of Gli2 and Gli3 activities by an amino-terminal repression domain: implication of Gli2 and Gli3 as primary mediators of Shh signaling. Development 126: 3915-3924, 1999[Abstract/Free Full Text].

111.   Sato, K, and Di Lauro R. Hepatocyte nuclear factor 3beta participates in the transcriptional regulation of the thyroperoxidase promoter. Biochem Biophys Res Commun 220: 86-93, 1996[ISI][Medline].

112.   Sato, TN, Tozawa Y, Deutsch U, Wolburg-Buchholz K, Fujiwara Y, Gendron-Maguire M, Gridley T, Wolburg H, Risau W, and Qin Y. Distinct roles of the receptor tyrosine kinases Tie-1 and Tie-2 in blood vessel formation. Nature 376: 70-74, 1995[ISI][Medline].

113.   Sawaya, PL, Stripp BR, Whitsett JA, and Luse DS. The lung-specific CC10 gene is regulated by transcription factors from the AP-1, octamer, and hepatocyte nuclear factor 3 families. Mol Cell Biol 13: 3860-3871, 1993[Abstract].

114.   Sekine, K, Ohuchi H, Fujiwara M, Yamasaki M, Yoshizawa T, Sato T, Yagishita N, Matsui D, Koga Y, Itoh N, and Kato S. Fgf10 is essential for limb and lung formation. Nat Genet 21: 138-141, 1999[ISI][Medline].

115.   Shalaby, F, Rossant J, Yamaguchi TP, Gertsenstein M, Wu XF, Breitman ML, and Schuh AC. Failure of blood-island formation and vasculogenesis in Flk-1-deficient mice. Nature 376: 62-66, 1995[ISI][Medline].

116.   Shaw-White, JR, Bruno MD, and Whitsett JA. GATA-6 activates transcription of thyroid transcription factor-1. J Biol Chem 274: 2658-2664, 1999[Abstract/Free Full Text].

117.   Shih, DQ, Navas MA, Kuwajima S, Duncan SA, and Stoffel M. Impaired glucose homeostasis and neonatal mortality in hepatocyte nuclear factor 3alpha -deficient mice. Proc Natl Acad Sci USA 96: 10152-10157, 1999[Abstract/Free Full Text].

118.   Shinbrot, E, Peters KG, and Williams LT. Expression of the platelet-derived growth factor beta  receptor during organogenesis and tissue differentiation in the mouse embryo. Dev Dyn 199: 169-175, 1994[ISI][Medline].

119.   Simonet, WS, DeRose ML, Bucay N, Nguyen HQ, Wert SE, Zhou L, Ulich TR, Thomason A, Danilenko DM, and Whitsett JA. Pulmonary malformation in transgenic mice expressing human keratinocyte growth factor in the lung. Proc Natl Acad Sci USA 92: 12461-12465, 1995[Abstract].

120.   Souza, P, Tanswell AK, and Post M. Different roles for PDGF-alpha and -beta receptors in embryonic lung development. Am J Respir Cell Mol Biol 15: 551-562, 1996[Abstract].

121.   Stahlman, MT, Gray ME, and Whitsett JA. Temporal-spatial distribution of hepatocyte nuclear factor-3beta in developing human lung and other foregut derivatives. J Histochem Cytochem 46: 955-962, 1998[Abstract/Free Full Text].

122.   Stripp, BR, Sawaya PL, Luse DS, Wikenheiser KA, Wert SE, Huffman JA, Lattier DL, Singh G, Katyal SL, and Whitsett JA. cis-acting elements that confer lung epithelial cell expression of the CC10 gene. J Biol Chem 267: 14703-14712, 1992[Abstract/Free Full Text].

123.   Sund, NJ, Ang SL, Sackett SD, Shen W, Daigle N, Magnuson MA, and Kaestner KH. Hepatocyte nuclear factor 3beta (Foxa2) is dispensable for maintaining the differentiated state of the adult hepatocyte. Mol Cell Biol 20: 5175-5183, 2000[Abstract/Free Full Text].

124.   Tichelaar, JW, Lim L, Costa RH, and Whitsett JA. HNF-3/forkhead homologue-4 influences lung morphogenesis and respiratory epithelial cell differentiation in vivo. Dev Biol 213: 405-417, 1999[ISI][Medline].

125.   Tichelaar, JW, Lu W, and Whitsett JA. Conditional expression of fibroblast growth factor-7 in the developing and mature lung. J Biol Chem 275: 11858-11864, 2000[Abstract/Free Full Text].

126.   Tichelaar, JW, Wert SE, Costa RH, Kimura S, and Whitsett JA. HNF-3/forkhead homologue-4 (HFH-4) is expressed in ciliated epithelial cells in the developing mouse lung. J Histochem Cytochem 47: 823-832, 1999[Abstract/Free Full Text].

127.   Vittet, D, Buchou T, Schweitzer A, Dejana E, and Huber P. Targeted null-mutation in the vascular endothelial-cadherin gene impairs the organization of vascular-like structures in embryoid bodies. Proc Natl Acad Sci USA 94: 6273-6278, 1997[Abstract/Free Full Text].

128.   Volpe, MV, Martin A, Vosatka RJ, Mazzoni CL, and Nielsen HC. Hoxb-5 expression in the developing mouse lung suggests a role in branching morphogenesis and epithelial cell fate. Histochem Cell Biol 108: 495-504, 1997[ISI][Medline].

129.   Wang, JC, Waltner-Law M, Yamada K, Osawa H, Stifani S, and Granner DK. Transducin-like enhancer of split proteins, the human homologs of Drosophila groucho, interact with hepatic nuclear factor 3(beta). J Biol Chem 275: 18418-18423, 2000[Abstract/Free Full Text].

130.   Warburton, D, Schwarz M, Tefft D, Flores-Delgado G, Anderson KD, and Cardoso WV. The molecular basis of lung morphogenesis. Mech Dev 92: 55-81, 2000[ISI][Medline].

131.   Weaver, M, Dunn NR, and Hogan BL. Bmp4 and Fgf10 play opposing roles during lung bud morphogenesis. Development 127: 2695-2704, 2000[Abstract/Free Full Text].

132.   Weaver, M, Yingling JM, Dunn NR, Bellusci S, and Hogan BL. Bmp signaling regulates proximal-distal differentiation of endoderm in mouse lung development. Development 126: 4005-4015, 1999[Abstract/Free Full Text].

133.   Weigel, D, and Jackle H. The fork head domain: a novel DNA binding motif of eukaryotic transcription factors? Cell 63: 455-456, 1990[ISI][Medline].

134.   Weinstein, DC, Ruiz i Altaba A, Chen WS, Hoodless P, Prezioso VR, Jessell TM, and Darnell J, Jr. The winged-helix transcription factor HNF-3beta is required for notochord development in the mouse embryo. Cell 78: 575-588, 1994[ISI][Medline].

135.   Whelan, J. Selectin synthesis and inflammation. Trends Biochem Sci 21: 65-69, 1996[ISI][Medline].

136.   Whitsett, J. A lungful of transcription factors. Nat Genet 20: 7-8, 1998[ISI][Medline].

137.   Whitsett, JA, and Glasser SW. Regulation of surfactant protein gene transcription. Biochim Biophys Acta 19: 2-3, 1998.

138.   Whitsett, JA, and Tichelaar JW. Forkhead transcription factor HFH-4 and respiratory epithelial cell differentiation. Am J Respir Cell Mol Biol 21: 153-154, 1999[Free Full Text].

139.   Yan, C, Sever Z, and Whitsett JA. Upstream enhancer activity in the human surfactant protein B gene is mediated by thyroid transcription factor 1. J Biol Chem 270: 24852-24857, 1995[Abstract/Free Full Text].

140.   Yancopoulos, GD, Davis S, Gale NW, Rudge JS, Wiegand SJ, and Holash J. Vascular-specific growth factors and blood vessel formation. Nature 407: 242-248, 2000[ISI][Medline].

141.   Yao, KM, Sha M, Lu Z, and Wong GG. Molecular analysis of a novel winged helix protein, WIN. Expression pattern, DNA binding property, and alternative splicing within the DNA binding domain. J Biol Chem 272: 19827-19836, 1997[Abstract/Free Full Text].

142.   Ye, H, Holterman A, Yoo KW, Franks RR, and Costa RH. Premature expression of the winged helix transcription factor HFH-11B in regenerating mouse liver accelerates hepatocyte entry into S-phase. Mol Cell Biol 19: 8570-8580, 1999[Abstract/Free Full Text].

143.   Ye, H, Kelly TF, Samadani U, Lim L, Rubio S, Overdier DG, Roebuck KA, and Costa RH. Hepatocyte nuclear factor 3/fork head homolog 11 is expressed in proliferating epithelial and mesenchymal cells of embryonic and adult tissues. Mol Cell Biol 17: 1626-1641, 1997[Abstract].

144.   Yuan, B, Li C, Kimura S, Engelhardt RT, Smith BR, and Minoo P. Inhibition of distal lung morphogenesis in Nkx2.1(-/-) embryos. Dev Dyn 217: 180-190, 2000[ISI][Medline].

145.   Zaret, K. Developmental competence of the gut endoderm: genetic potentiation by GATA and HNF3/fork head proteins. Dev Biol 209: 1-10, 1999[ISI][Medline].

146.   Zeng, X, Wert SE, Federici R, Peters KG, and Whitsett JA. VEGF enhances pulmonary vasculogenesis and disrupts lung morphogenesis in vivo. Dev Dyn 211: 215-227, 1998[ISI][Medline].

147.   Zhang, L, Whitsett JA, and Stripp BR. Regulation of Clara cell secretory protein gene transcription by thyroid transcription factor-1. Biochim Biophys Acta 28: 359-367, 1997.

148.   Zhou, L, Dey CR, Wert SE, Yan C, Costa RH, and Whitsett JA. Hepatocyte nuclear factor-3beta limits cellular diversity in the developing respiratory epithelium and alters lung morphogenesis in vivo. Dev Dyn 210: 305-314, 1997[ISI][Medline].

149.   Zhou, L, Lim L, Costa RH, and Whitsett JA. Thyroid transcription factor-1, hepatocyte nuclear factor-3beta , surfactant protein B, C, and Clara cell secretory protein in developing mouse lung. J Histochem Cytochem 44: 1183-1193, 1996[Abstract/Free Full Text].


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