Medical Research Council Centre for Developmental Neurobiology, King's College London, London SE1 9RT, United Kingdom
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Endogenous retinoids have been
implicated in alveologenesis in both the rat and the mouse, and
exogenous retinoic acid (RA) can reverse or partially reverse
experimental emphysema in adult rat and mouse models by an unknown
mechanism. In this study, we examine the cellular and molecular biology
of retinoid signaling during alveologenesis in the mouse. We describe
the temporal and spatial expression of the retinoid binding
proteins CRBP-I, CRBP-II, and CRABP-I using RT-PCR and
immunohistochemistry. We identify the retinoic acid receptor isoforms
RAR-1, RAR-
2, RAR-
4, and RAR-
2 and describe their temporal
and spatial expression using RT-PCR and in situ hybridization. We
demonstrate that both retinoid binding proteins and RAR isoforms are
temporally regulated and found within the alveolar septal regions
during alveologenesis. These data support a role of dynamic endogenous
RA signaling during alveolar formation.
lung development; alveolar regeneration; bronchopulmonary dysplasia; emphysema
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
ALVEOLI ARE FORMED as a developmentally regulated, largely postnatal event in rats, mice, and humans (1, 4, 41). Retinoids are a family of molecules derived from vitamin A (retinol) and include the biologically active metabolite retinoic acid (RA). Alveologenesis is associated with dramatic changes in the metabolism of endogenous retinoids in both rats and mice from storage forms such as retinyl esters to metabolites such as retinol and RA (11, 14, 27). Both retinol and RA are bound in the cytoplasm by binding proteins, cellular retinol binding protein (CRBP-I and CRBP-II), and cellular retinoic acid binding protein (CRABP-I and CRABP-II). These families of binding proteins regulate the biological action of retinol and RA (31). Previous Northern blot analysis of CRBP-I and CRABP-I mRNA has demonstrated upregulation of both genes during alveologenesis in both whole rat lung tissue and isolated lipid-laden fibroblasts (27). Dexamethasone administered to postnatal rat pups between postnatal day 4 (P4) and P14 disrupts alveolar septation (21) and results in downregulation of CRBP-I and CRABP-I (37). The spatial distribution of CRBP-I and CRABP-I within lung tissue during alveologenesis has not been described.
The cellular effects of RA are mediated through the action of two
classes of nuclear receptors, the retinoic acid receptors (RARs), which
are activated by all-trans-RA and 9-cis-RA, and the retinoid X receptors (RXRs), which are activated by
9-cis-RA only (16). RARs are of three major
subtypes, ,
, and
, of which there are numerous isoforms
created by alternative splicing and differential promoter usage
(17). RARs form heterodimers with RXRs and act as
ligand-activated transcription factors to regulate downstream gene
expression. RXRs can act as homodimers or heterodimers with a variety
of orphan receptors such as peroxisome proliferator-activated receptor
(16). Elastin is a major structural component of the
alveolus. Both the expression of its precursor gene, tropoelastin, and
elastin deposition are regulated during alveologenesis (9, 32,
35). RA has been shown to regulate transcription of the
tropoelastin gene in vitro (26), suggesting that
tropoelastin may be a target gene of RA during alveologenesis.
It has been suggested, on the basis of differential expression patterns
in the embryo, that each of the RAR isoforms has specific roles in
development (5). Alveologenesis in the rat is associated with transcriptional upregulation of the RAR genes (27),
and recent analysis of alveologenesis in RAR null mutants has
demonstrated altered patterns of alveolar formation, with RAR- a
negative (24) and RAR-
a positive (25)
factor in the regulation of alveologenesis. Exogenous RA has been shown
to increase the number of alveoli in the neonatal rat (22)
and can reverse features of pulmonary emphysema in the adult rat
(3, 23, 36). From these observations, it is clear that
RARs may provide a unique therapeutic target in the development of
highly specific agents to manipulate the formation of alveoli.
In this study, we sought to identify elements of the retinoid-signaling
pathway during postnatal alveologenesis in the mouse. Using RT-PCR
together with primers specific to the gene of interest, we have
searched for 25 known retinoid-signaling genes. Of these genes, we
identify and characterize temporal expression patterns of the retinoid
binding proteins CRBP-I, CRBP-II, and CRABP-I, the specific isoforms of
the retinoid receptors RAR-1, RAR-
2, RAR-
4, and RAR-
2,
through alveolar formation. We use immunohistochemistry to localize
CRBP-I and CRABP-I proteins and in situ hybridization with specific RNA
riboprobes to describe the spatial expression of the RAR genes in the
postnatal mouse lung. We suggest a molecular model of RA signaling
involving retinoid binding proteins and RARs that regulate the effects
of endogenous RA during alveologenesis.
![]() |
MATERIALS AND METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Animal care. All experiments were conducted in accordance with local ethics committee guidelines using outbred TO mice (Harlan, UK), both male and female neonatal mice at postnatal P1, P4, P9, P15, and adult female (over 8 wk of age). All animals were given access to water and laboratory chow ad libitum.
Tissue preparation.
P1, P4, P9, P15, and adult animals were culled by neck dislocation, and
their lungs were dissected free. Lung tissue for RT-PCR analysis was
removed, washed in phosphate-buffered saline (PBS), and immediately
stored at 70°C. Lungs for in situ hybridization studies and
immunocytochemistry were dissected out and removed. The trachea was
cannulated, tied firmly in place, and infused with either 4%
paraformaldehyde (PFA) or perfix (4% PFA, 20% isopropryl alcohol, and
2% trichloroacetic acid) at a pressure of 20 cmH2O for
24 h. The lungs were then dehydrated through a graded series of
alcohol solutions and xylene and embedded in paraffin wax. The
lungs were sectioned at 5 µm, and the sections were mounted on
polylysine-coated glass slides (BDH, Dorset, UK).
RT-PCR analysis.
To identify which retinoid binding proteins and RAR isoforms were
present during alveologenesis, semiquantitative RT-PCR was used. RNA
was extracted using a Qiagen RNAeasy kit, and cDNA was prepared with
the use of an Amersham first-strand cDNA synthesis kit, as described in
the manufacturer's instructions. RNA extractions were performed from
at least four lungs from each age group and analyzed
separately. The primers used (see Table
1) were from mouse CRBP-I, CRBP-II,
CRABP-I, CRABP-II, RARs (RAR- 1-7, RAR-
1-4, RAR-
1-7), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH)
(15, 18, 29, 40). Amplification was carried out in the
linear range for each primer, and their levels of expression were
compared with GAPDH. Amplification was carried out as follows: denaturation for 30 s at 95°C, annealing for 30 s at
55°C, and extension for 30 s at 72°C. One-fifth of the
resultant product was then run on a 1% agarose gel. Gels were scanned
and analyzed by gel analyst software from Scion (available free of
charge at http://www.scioncorp.com). The gels were normalized
for GAPDH expression. Each experiment was repeated at least three times with similar results.
|
In situ hybridization. Digoxygenin-labeled riboprobes were synthesized from the appropriate cDNA. Slides were rehydrated, washed once with PBS, and fixed in 4% PFA for 30 min. They were then washed twice for 5 min in PBS-0.05% Tween (PBT) and dehydrated through graded ethanol solutions. Hybridization was carried out at 55°C overnight with a 1:100 dilution of RNA probe. The buffer consisted of 50% formamide, 5× SSC, 0.05% heparin, 0.5% Tween 20, and 1% yeast tRNA. Slides were washed sequentially for 15 min at 55°C in 50% hybridization buffer, 50% 2× SSC, 2× SSC, and finally in 0.2% SSC. They were then washed at RT for 5 min each in 75% 0.2× SSC, 25% PBT, 50% 0.2× SSC, 50% PBT, 25% 0.2× SSC, 75% PBT, and PBT. Slides were blocked in 2% sheep serum in PBT for 1 h and incubated with anti-digoxygenin antibody overnight at 4°C. Slides were then washed eight times in PBT for 2 h and were developed using nitro blue tetrazolium/5-bromo-4-chloro-3-indolylphosphate-p-toluidine salt according to instructions (Boehringer Mannheim). Control experiments using sense probes and absent probe revealed no signal.
Immunohistochemistry. Slides were dewaxed to PBS through graded alcohol solutions and blocked with goat serum for 1 h. They were then incubated in primary antibody at 4°C overnight and washed three times in PBS. Subsequent steps using secondary antibody, avidin-biotin complex reagent, and diaminobenzidine were performed according to a Vector ABC Elite kit (Vector Labs, Peterborough, UK). The monoclonal CRABP-I antibody was obtained from Affinity Bioreagents, and the affinity-purified CRBP-I and CRABP-I antibodies were gifts from Dr. U. Eriksson (Stockholm, Sweden). Appropriate dilutions of antibody were previously established. Controls for immunoreactivity were absent primary antibody, nonimmune serum, and other IgG antibodies. Slides were lightly counterstained with hematoxylin after immunohistochemistry.
Statistical analysis. A time course analysis of the RT-PCR data was performed using one-way analysis of variance statistics with Bonferroni's adjustment for multiple comparisons. Results were considered significant at P < 0.05.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The temporal expression of the retinoid binding proteins during alveolar septation. Previous studies have indicated that, in the mouse, alveolar septation occurs between P4 and P14 (1). To identify mRNA for retinol and RA binding proteins during alveologenesis, we used RT-PCR with RNA isolated from P1, P4, P9, P15, and adult mouse lung tissue and primers specific to CRBP-I, CRBP-II, CRABP-I, and CRABP-II. We positively identified CRBP-I, CRBP-II, and CRABP-I in all stages of postnatal lung; we could not identify CRABP-II in any of the tissues.
The temporal expression of CRBP-I, CRBP-II, and CRABP-I mRNA can be seen in the RT-PCR studies (Fig. 1, A-C, respectively). CRBP-I, CRBP-II, and CRABP-I mRNAs are all significantly upregulated in the early postnatal mouse lung during alveolar septation. CRBP-I peaks at P9 (P < 0.05 compared with adult), CRBP-II peaks at P4 (P < 0.05 compared with adult), and CRABP-I peaks in the P9 lung (P < 0.05 compared with adult). These data are in general agreement with the previous Northern blot analysis of CRBP-I and CRABP-I mRNA with both binding proteins significantly upregulated during the period of alveologenesis in the postnatal rat lung (27, 34). CRBP-II mRNA has been identified previously in postnatal lung tissue (33) but was not studied during the period of alveologenesis.
|
CRBP-I protein localization in the postnatal mouse lung.
To verify our RT-PCR analysis and examine the spatial distribution of
CRBP-I protein during alveolar septation, we used an affinity-purified
CRBP-I-specific antibody on sections of P1, P4, P9, P15, and adult
lung. The preparation and specificity of this antibody for mouse tissue
have been reported previously (10). Specifically, it does
not cross-react with CRBP-II or CRABP-I (13). CRBP-I
protein was identified in the alveolar septal tissue but not in the
bronchial epithelium (Fig. 2,
A and B). The locations of cells expressing
signal changes through the stages examined are shown in Fig.
3, A-D. In the P1 lung,
only occasional weakly stained cells are identified in the thick walls
of the alveolar saccules (Fig. 3A). The pattern of staining
is increased in the P4 lung with CRBP-I protein identified in the
erupting primary septa and alveolar septal tissue (Fig. 3B).
There is widespread, but not ubiquitous, CRBP-I protein labeled in the
P9 lung, with strongly labeled alveolar septal cells adjacent to
unlabeled alveolar septal cells (Fig. 3C). The P15 lung has
a much more restricted pattern of CRBP-I protein expression, with only
scattered cells labeled. The pattern of intracellular labeling is
different in the P15 lung compared with the P9 lung, in which the
labeling is more discrete and punctate (Fig. 3D).
|
|
CRABP-I localization in the postnatal mouse lung.
We used both an affinity-purified polyclonal antibody and a
commercially available monoclonal antibody to CRABP-I to observe the
spatial expression of this protein during the period of alveologenesis. The preparation and specificity of the affinity-purified antibody for
mouse has been previously reported (20). Specifically, it does not cross-react with CRABP-II (10). CRABP-I protein
is identified in the alveolar septal regions in a similar distribution to the CRBP-I protein (Fig. 4).
Consistent with the RT-PCR data of CRABP-I mRNA, we identify CRABP-I
protein at all stages examined. Like the distribution of the CRBP-I
protein, CRABP-I protein is identified strongly in the alveolar septal
regions and pleural mesothelial cells but not in bronchial epithelium.
Within the alveolar septal region, there are strongly labeled cells
adjacent to unlabeled alveolar septal cells. The precise identity of
CRABP-I-labeled cells is unknown.
|
RAR isoform identification and temporal expression in the postnatal
mouse lung.
Previous Northern blot and RT-PCR studies have revealed changes in RAR
gene expression during alveolar formation in the postnatal rat lung
(27). The expression of the various RAR isoforms has not
been reported during alveologenesis in mouse. In this study, we used
RT-PCR with primers specific to each of the seven RAR-, four
RAR-
, and seven RAR-
isoforms, to identify the major isoforms of
the three RAR genes through alveolar septation. Of the 18 isoforms analyzed, only RAR-
1, -
2, -
4, and -
2 mRNA were identified in the postnatal mouse lung, and all showed dramatic changes in temporal expression during alveologenesis. All identified isoforms are
significantly upregulated at P4 (P < 0.05) compared
with adult (Fig. 5, A-D).
|
Spatial expression of RARs in the postnatal mouse lung.
The in situ hybridization studies confirm the RT-PCR findings that
RAR-, -
, and -
are present in postnatal mouse lung tissue (Fig. 6). RAR expression is localized to
bronchial epithelium, bronchial and vascular smooth muscle, pleura, and
scattered cells within the alveolar regions, some of which have the
characteristic morphology of type II pneumocytes. More specific cell
identification is beyond the resolution of this study. These results
are in general agreement with previous studies identifying RARs in
bronchial epithelium (8), lipid-containing fibroblasts
(27), and type II cells (30). No obvious
differences in the distribution of these receptors were noted over
time.
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
We have chosen to examine retinoid signaling during mouse alveologenesis to exploit both the powerful genetics and molecular biology available to this model. Alveolar formation in the rat is associated with transcriptional regulation of CRBP-I and CRABP-I (27) mRNA (37). Our RT-PCR data in the mouse support this association. In addition, we identify another retinoid binding protein gene, CRBP-II, that is also transcriptionally regulated during alveologenesis. The function of CRBP-II is not well understood. It has been largely studied in the intestinal epithelium, where it is thought to function in the uptake of dietary retinoids (33). Both the temporal and spatial restriction of the retinoid binding proteins suggest a role for these genes in modulating RA signaling during alveolar formation. Interestingly, neither CRBP-I nor CRABP-I protein is detected in the bronchial epithelium, a tissue known to be extremely retinoid sensitive. One of the earliest features of vitamin A deficiency is the metaplastic transformation of pseudostratified epithelium into squamous keratinizing epithelium (38, 39). Therefore, it would be interesting to examine the distribution of CRBP-II in the postnatal lung. We speculate that bronchial epithelium might express this protein.
Although retinoid binding proteins are temporally and spatially associated with alveologenesis, CRBP-I null mutants have no reported lung phenotype (12). However, more recent in vitro results demonstrate that CRBP-I null mutant lungs are more sensitive to the effects of a pan-RAR antagonist than wild-type controls (28), suggesting that the CRBP-I null mutant lungs do indeed have a subtle phenotype. To our knowledge, a detailed morphometric analysis of alveolar architecture in the CRBP-I null mutants has not been published.
Of the 18 reported isoforms of the RARs, we identify RARs -1, -
2,
-
4, and -
2, all of which are transcriptionally regulated in the
postnatal mouse lung. All identified isoforms are significantly upregulated in the neonatal period compared with expression in the
adult, suggesting a role in endogenous RA signaling. Data from RAR-
null mutants, together with the use of RAR-
-specific agonists,
suggest that RAR-
functions as an endogenous inhibitor of
alveologenesis (24). Conversely, analysis of the RAR-
/
/RXR-
+/
compound null mutants has revealed defects in
alveologenesis, suggesting a requirement for RAR-
(25).
In light of the identification of the RAR isoforms, this suggests that
either RAR-
2 may function as a positive regulator of alveologenesis
or RAR-
2/RAR-
4 may function as negative regulators of
alveologenesis, or both. We have previously reported the value of
retinoid receptor-specific agents, both agonists and antagonists in
nerve and limb regeneration studies (6, 7, 19). Further
use of these agents may be important in deciphering the role of RAR
regulation in both alveologenesis and alveolar regeneration.
The temporal and spatial distribution of the RARs suggests not only a role in alveologenesis but also a function in the adult lung. The effects of vitamin A deficiency on the bronchial epithelium are well known (38, 39). More recently, vitamin A depletion has been reported to result in defects in the alveolar epithelium (2) with areas of emphysema-like changes. It is tempting to speculate that, in the adult animal, endogenous RA acting via binding proteins and RARs has a role in mediating endogenous alveolar repair.
In summary, this study demonstrates, in a second species of altricial animals, the association of alveologenesis with transcriptional regulation of retinoid binding protein and RAR genes. We provide data on both the temporal and spatial distribution of CRBP-I and CRABP-I and identify the specific isoforms of the RARs associated with alveolar formation. This is further evidence to support a central role of retinoid signaling in postnatal alveologenesis. Understanding the molecular and cellular basis of alveolar formation will be fundamental to the development of novel therapies that promote alveolar regeneration or repair in diseases such as bronchopulmonary dysplasia or emphysema.
![]() |
ACKNOWLEDGEMENTS |
---|
We thank Dr. Ulf Eriksson, Ludwig Institute, Stockholm, Sweden, for
the CRBP-I and CRABP-I antibody and Professor P. Chambon, IBCM,
Strasbourg, France, for the RAR-, RAR-
, and RAR-
plasmids; and
Katie Adams for technical assistance.
![]() |
FOOTNOTES |
---|
All work is funded by Wellcome Trust. M. Hind is a Wellcome Trust Research Training Fellow.
Address for reprint requests and other correspondence: M. Hind, Centre for Developmental Neurobiology, Fourth Floor New Hunts House, King's College London, Guy's Campus, London SE1 9RT, United Kingdom (E-mail: matthew.hind{at}kcl.ac.uk).
The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
10.1152/ajplung.00196.2001
Received 5 June 2001; accepted in final form 15 October 2001.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
1.
Amy, RW,
Bowes D,
Burri PH,
Haines J,
and
Thurlbeck WM.
Postnatal growth of the mouse lung.
J Anat
124:
131-151,
1977[ISI][Medline].
2.
Baybutt, RC,
Hu L,
and
Molteni A.
Vitamin A deficiency injures lung and liver parenchyma and impairs function of rat type II pneumocytes.
J Nutr
130:
1159-1165,
2000
3.
Belloni, PN,
Garvin L,
Mao CP,
Bailey-Healy I,
and
Leaffer D.
Effects of all-trans-retinoic acid in promoting alveolar repair.
Chest
117:
235S-241S,
2000
4.
Burri, PH,
Dbaly J,
and
Weibel ER.
The postnatal growth of the rat lung. I. Morphometry.
Anat Rec
178:
711-730,
1974[ISI][Medline].
5.
Chambon, P.
A decade of molecular biology of retinoic acid receptors.
FASEB J
10:
940-954,
1996
6.
Corcoran, J,
and
Maden M.
Nerve growth factor acts via retinoic acid synthesis to stimulate neurite outgrowth.
Nat Neurosci
2:
307-308,
1999[ISI][Medline].
7.
Corcoran, J,
Shroot B,
Pizzey J,
and
Maden M.
The role of retinoic acid receptors in neurite outgrowth from different populations of embryonic mouse dorsal root ganglia.
J Cell Sci
113:
2567-2574,
2000
8.
Dolle, P,
Ruberte E,
Leroy P,
Morriss-Kay G,
and
Chambon P.
Retinoic acid receptors and cellular retinoid binding proteins. I. A systematic study of their differential pattern of transcription during mouse organogenesis.
Development
110:
1133-1151,
1990[Abstract].
9.
Dubick, MA,
Rucker RB,
Cross CE,
and
Last JA.
Elastin metabolism in rodent lung.
Biochim Biophys Acta
672:
303-306,
1981[ISI][Medline].
10.
Eriksson, U,
Hansson E,
Nordlinder H,
Busch C,
Sundelin J,
and
Peterson PA.
Quantitation and tissue localization of the cellular retinoic acid-binding protein.
J Cell Physiol
133:
482-490,
1987[ISI][Medline].
11.
Geevarghese, SK,
and
Chytil F.
Depletion of retinyl esters in the lungs coincides with lung prenatal morphological maturation.
Biochem Biophys Res Commun
200:
529-535,
1994[ISI][Medline].
12.
Ghyselinck, NB,
Bavik C,
Sapin V,
Mark M,
Bonnier D,
Hindelang C,
Dierich A,
Nilsson CB,
Hakansson H,
Sauvant P,
Azais-Braesco V,
Frasson M,
Picaud S,
and
Chambon P.
Cellular retinol-binding protein I is essential for vitamin A homeostasis.
EMBO J
18:
4903-4914,
1999
13.
Gustafson, AL,
Dencker L,
and
Eriksson U.
Non-overlapping expression of CRBP I and CRABP I during pattern formation of limbs and craniofacial structures in the early mouse embryo.
Development
117:
451-460,
1993
14.
Hind, MD,
Corcoran J,
and
Maden M.
Alveolar proliferation, retinoid synthesizing enzymes and endogenous retinoids in the postnatal mouse lung: different roles for Aldh-1 and Raldh-2.
Am J Respir Cell Mol Biol
26:
1-7,
2002
15.
Kastner, P,
Krust A,
Mendelsohn C,
Garnier JM,
Zelent A,
Leroy P,
Staub A,
and
Chambon P.
Murine isoforms of retinoic acid receptor gamma with specific patterns of expression.
Proc Natl Acad Sci USA
87:
2700-2704,
1990[Abstract].
16.
Kliewer, SA,
Umesono K,
Evans RM,
and
Manglesdorf DJ.
The retinoid X receptors: modulators of multiple hormone signaling pathways. Vitamin A in health and disease. New York: Marcel Dekker, 1994, p. 239-255.
17.
Leid, M,
Kastner P,
and
Chambon P.
Multiplicity generates diversity in the retinoic acid signalling pathways.
Trends Biochem Sci
17:
427-433,
1992[ISI][Medline].
18.
Leroy, P,
Krust A,
Zelent A,
Mendelsohn C,
Garnier JM,
Kastner P,
Dierich A,
and
Chambon P.
Multiple isoforms of the mouse retinoic acid receptor alpha are generated by alternative splicing and differential induction by retinoic acid.
EMBO J
10:
59-69,
1991[Abstract].
19.
Maden, M.
Retinoids as endogenous components of the regenerating limb and tail.
Wound Repair Regen
6:
358-365,
1998[Medline].
20.
Maden, M,
Horton C,
Graham A,
Leonard L,
Pizzey J,
Siegenthaler G,
Lumsden A,
and
Eriksson U.
Domains of cellular retinoic acid-binding protein I (CRABP I) expression in the hindbrain and neural crest of the mouse embryo.
Mech Dev
37:
13-23,
1992[ISI][Medline].
21.
Massaro, D,
Teich N,
Maxwell S,
Massaro GD,
and
Whitney P.
Postnatal development of alveoli. Regulation and evidence for a critical period in rats.
J Clin Invest
76:
1297-1305,
1985[ISI][Medline].
22.
Massaro, GD,
and
Massaro D.
Postnatal treatment with retinoic acid increases the number of pulmonary alveoli in rats.
Am J Physiol Lung Cell Mol Physiol
270:
L305-L310,
1996
23.
Massaro, GD,
and
Massaro D.
Retinoic acid treatment abrogates elastase-induced pulmonary emphysema in rats.
Nat Med
3:
675-677,
1997[ISI][Medline]. [Corrigenda. Nat Med 3: July 1997, p. 805.]
24.
Massaro, GD,
Massaro D,
Chan WY,
Clerch LB,
Ghyselinck N,
Chambon P,
and
Chandraratna RA.
Retinoic acid receptor-: an endogenous inhibitor of the perinatal formation of pulmonary alveoli.
Physiol Genomics
4:
51-57,
2000
25.
McGowan, S,
Jackson SK,
Jenkins-Moore M,
Dai HH,
Chambon P,
and
Snyder JM.
Mice bearing deletions of retinoic acid receptors demonstrate reduced lung elastin and alveolar numbers.
Am J Respir Cell Mol Biol
23:
162-167,
2000
26.
McGowan, SE,
Doro MM,
and
Jackson SK.
Endogenous retinoids increase perinatal elastin gene expression in rat lung fibroblasts and fetal explants.
Am J Physiol Lung Cell Mol Physiol
273:
L410-L416,
1997
27.
McGowan, SE,
Harvey CS,
and
Jackson SK.
Retinoids, retinoic acid receptors, and cytoplasmic retinoid binding proteins in perinatal rat lung fibroblasts.
Am J Physiol Lung Cell Mol Physiol
269:
L463-L472,
1995
28.
Mollard, R,
Ghyselinck NB,
Wendling O,
Chambon P,
and
Mark M.
Stage dependent responses of the developing lung to retinoic acid signalling.
Int J Dev Biol
44:
457-462,
2000[ISI][Medline].
29.
Nagpal, S,
Zelent A,
and
Chambon P.
RAR-beta 4, a retinoic acid receptor isoform is generated from RAR- 2 by alternative splicing and usage of a CUG initiator codon.
Proc Natl Acad Sci USA
89:
2718-2722,
1992[Abstract].
30.
Naltner, A,
Ghaffari M,
Conkright J,
and
Yan C.
Protein-protein interation of RAR alpha and thyroid transcription factor-1 in respiratory epithelial cells.
J Biol Chem
276:
21686-21691,
2001
31.
Napoli, JL.
Interactions of retinoid binding proteins and enzymes in retinoid metabolism.
Biochim Biophys Acta
1440:
139-162,
1999[ISI][Medline].
32.
Noguchi, A,
and
Samaha H.
Developmental changes in tropoelastin gene expression in the rat lung studied by in situ hybridization.
Am J Respir Cell Mol Biol
5:
571-578,
1991[ISI][Medline].
33.
Ong, DE.
A novel retinol-binding protein from rat. Purification and partial characterization.
J Biol Chem
259:
1476-1482,
1984
34.
Ong, DE,
and
Chytil F.
Changes in levels of cellular retinol and retinoic acid binding proteins of the liver and lung during perinatal development.
Proc Natl Acad Sci USA
73:
3976-3978,
1976[Abstract].
35.
Powell, JT,
and
Whitney PL.
Postnatal development of rat lung. Changes in lung lectin, elastin, acetylcholinesterase and other enzymes.
Biochem J
188:
1-8,
1980[ISI][Medline].
36.
Tepper, J,
Pfeiffer J,
Aldrich M,
Tumas D,
Kern J,
Hoffman E,
McLennan G,
and
Hyde D.
Can retinoic acid ameliorate the physiologic and morphologic effects of elastase instillation in the rat?
Chest
117:
242S-244S,
2000
37.
Whitney, D,
Massaro GD,
Massaro D,
and
Clerch LB.
Gene expression of cellular retinoid-binding proteins: modulation by retinoic acid and dexamethasone in postnatal rat lung.
Pediatr Res
45:
2-7,
1999[Abstract].
38.
Wolbach, SB,
and
Howe PR.
Tissue changes following deprivation of fat-soluble vitamin A.
J Exp Med
42:
753-777,
1925.
39.
Wolbach, SB,
and
Howe PR.
Epithelial repair and recovery from vitamin A deficiency.
J Exp Med
57:
511-526,
1932.
40.
Zelent, A,
Mendelsohn C,
Kastner P,
Krust A,
Garnier JM,
Ruffenach F,
Leroy P,
and
Chambon P.
Differentially expressed isoforms of the mouse retinoic acid receptor beta generated by usage of two promoters and alternative splicing.
EMBO J
10:
71-81,
1991[Abstract].
41.
Zeltner, TB,
Caduff JH,
Gehr P,
Pfenninger J,
and
Burri PH.
The postnatal development and growth of the human lung. I. Morphometry.
Respir Physiol
67:
247-267,
1987[ISI][Medline].