RAPID COMMUNICATION
Cloning of guinea pig surfactant protein A defines a distinct cellular
distribution pattern within the lung
Hai Tao
Yuan,
Sharon
Gowan,
Frank J.
Kelly, and
Colin D.
Bingle
Cardiovascular Research, The Rayne Institute, St. Thomas' Hospital,
London SE1 7EH; and Department of Toxicology, St. Bartholomew's
and the Royal London School of Medicine and Dentistry, London EC1
7ED, United Kingdom
 |
ABSTRACT |
A full-length cDNA to guinea pig pulmonary
surfactant protein (SP) A was cloned by screening a newborn guinea pig
lung cDNA library with a human SP-A cDNA probe. The full-length guinea
pig SP-A cDNA consists of 1,839 bp and is highly conserved at both nucleotide and amino acid sequence levels with those from other species. As expected, guinea pig SP-A mRNA is abundantly expressed in
adolescent lung tissue and is undetectable in nonpulmonary tissues. In
situ hybridization studies clearly show a unique cellular distribution
pattern of SP-A mRNA within the guinea pig lung. SP-A mRNA expression
is confined to cells of the alveolar epithelium with no expression in
the bronchiolar epithelial cells, whereas SP-B mRNA is expressed in
both alveolar and bronchiolar epithelial cell populations. This
distinct expression pattern suggests that the guinea pig lung will be a
useful model in which to study expression of transcription factors
implicated in the regulation of SP genes.
alveolar epithelium; gene expression; in situ hybridization
 |
INTRODUCTION |
FOUR SPECIFIC surfactant proteins (SP), designated
SP-A, SP-B, SP-C, and SP-D (14), have been identified within pulmonary surfactant (19). SP-A, the most abundant, is a highly glycosylated protein with a monomeric molecular mass of 26-38 kDa (5, 26). SP-A
contains a collagenous domain at its
NH2-terminal and is structurally
related to SP-D, mannose binding protein, and C1q, all members of the
collectin family of lectins (6). Multiple functions have been assigned
to SP-A, including binding to carbohydrates and interacting with
surfactant phospholipid (6, 16). SP-A, in the presence of
phosphatidylglycerol, calcium, and SP-B, forms structures resembling
tubular myelin, the extracellular form of pulmonary surfactant (23).
SP-A inhibits phospholipid secretion and enhances the uptake of
phospholipid by the respiratory epithelium in vitro (24, 29), thereby
regulating the uptake and recycling of surfactant, as well as enhancing
the surface-active properties of surfactant lipids. In addition, in
vitro studies have demonstrated that SP-A also participates in host
defense mechanisms by modulating the functions of alveolar macrophages,
such as the production of reactive oxygen species and inflammatory
cytokines (13, 25). Deletion of the SP-A gene in mice alters formation
of tubular myelin but otherwise has little effect on pulmonary
function, suggesting that the host defense functions of SP-A (21) may be more important than its role in surfactant metabolism (12).
Studies at both the protein and mRNA level have shown that SP-A is
localized to the alveolar type II epithelial cells of the lung in all
species studied (3, 10, 11, 17, 28). In addition, a number of studies
have also shown that SP-A is expressed in a subset of bronchiolar
epithelial cells in a variety of species, including humans (3, 10, 11,
28), although initial studies appeared not to show SP-A mRNA in human
bronchiolar epithelial cells (17).
Synthesis of SP and surfactant phospholipids are developmentally
regulated for the preparation for pulmonary function after birth (16).
Insufficient development of the pulmonary surfactant system is one of
the major pathogenic determinants of respiratory distress syndrome
(RDS) found in premature neonates (4). To facilitate a better
understanding of lung development and RDS in preterm babies, we
developed a guinea pig model of prematurity (9). Lung development in
the guinea pig is more advanced than in rodents, and these animals can
survive premature delivery (8, 9). Using this model, we reported that,
during the final 25% of gestation, there is a steady increase in
pulmonary phospholipid concentration. Coincidently, the relative
contribution of disaturated phospholipid species, the major active
lipid of surfactant, is also increased (8). To more fully address the
changes in SP-A gene expression in this model, we have now cloned a
full-length guinea pig SP-A cDNA. Unexpectedly, initial studies
performed with this probe in adolescent animals have revealed that the
cellular distribution of SP-A mRNA is unique to the guinea pig, with
expression being found only in the alveolar epithelial cells and not in
cells of the bronchiolar epithelium.
 |
MATERIALS AND METHODS |
Preparation of guinea pig tissue
samples. Tissues were collected from 60-day-old Hartley
strain guinea pigs obtained from our own colony. Under anesthesia,
animals were exsanguinated by abdominal aorta section, and the
pulmonary circulation was perfused free of blood with 50 ml of
sterilized 0.9% sodium chloride solution via the heart. The lungs were
then removed, washed immediately with ice-cold saline, dried with
tissue paper, and snap-frozen in liquid nitrogen for subsequent RNA
isolation. Heart, liver, spleen, and kidney tissues were also collected
and prepared in a similar manner. When lung tissue was prepared for in
situ hybridization, 10 ml of 4% formaldehyde in phosphate-buffered
saline (pH 7.0) were infused slowly by syringe through the trachea into
the lung tissue until the lung was fully expanded. The tissue was fixed in 4% formaldehyde for 24 h at room temperature and was embedded in
paraffin.
Isolation of guinea pig SP-A cDNA
clones. Poly(A)+
RNA was isolated from a newborn guinea pig lung by the FastTract system (Invitrogen, De Schelp, NL), and 5 µg were used to generate a directionally cloned oligo(dT) primed cDNA library in
Zap
(Stratagene, Cambridge, UK) according to the manufacturer's
instructions. The library was amplified one time, and random
amplification of plaques suggested that the average insert size was
>1.3 kb. Four hundred thousand plaque-forming units
(pfu) were screened with a
32P-labeled, full-length human
SP-A cDNA probe (26). Membranes were prehybridized with QuickHyb
solution (Stratagene) for 1 h at 68°C, hybridized for 2 h at the
same temperature, and washed in a final solution of 0.1× SSC
(1× SSC = 150 mM sodium chloride and 15 mM sodium citrate) and
0.1% sodium dodecyl sulfate at 65°C for 30 min. Plaques that
survived a secondary screen were recovered by excision rescue, and the
phagmids were used directly for further analysis. Plasmid DNA was
sequenced with the fmol polymerase chain reaction (PCR) sequencing kit
(Promega, Southampton, UK), using specific external and internal
primers. Compilation and computer analysis of DNA
sequences were performed with the PC/Gene databases.
Total RNA isolation and Northern
blotting. Total RNA samples were isolated from lung,
heart, kidney, liver, and spleen tissues of adolescent guinea pigs as
described previously (30). Characterization of tissue-specific
expression of SP-A mRNA before in situ hybridization was performed by
Northern blotting. Total RNA samples (10 µg/lane) were
electrophoresed in 1% agarose denaturing gels, transferred to
hybridization transfer membranes (Hybond-N; Amersham, Amersham, UK),
and fixed with ultraviolet light. The blots were hybridized with a
random primed 32P-labeled SP-A
cDNA probe for 2 h at 65°C using QuickHyb solution (Stratagene) and
were subjected to stringent washing as described previously (30). The
X-ray films were exposed to the membranes at
70°C. To
confirm the existence of total RNA in all lanes, the blot was stripped
and subsequently was rehybridized with
32P-labeled guinea pig catalase
probe, as previously described (30).
In situ hybridization. For in situ
hybridization studies, a portion of the guinea pig SP-A cDNA
corresponding to part of the 3'-untranslated region (nucleotides
1168-1524) was amplified by PCR using the following primers:
forward primer 5'-GTC CCA TCA AGA TGT AG-3'; reverse primer
5'-AGG CCA TGA TTT GGC TGG-3'. The 356-bp insert was
directly cloned into pCRII (Invitrogen) and was sequenced to determine
the orientation of the insert. The SP-B probe was generated from a
full-length guinea pig cDNA (C. D. Bingle, S. Gowan, and H. T. Yuan,
unpublished observations), and the resulting transcripts
were subjected to a limited alkaline hydrolysis. Sense and antisense
UTP-digoxigenin-labeled riboprobes were prepared using linearized
plasmid cDNA as template, the appropriate RNA polymerase, and the
conditions recommended in the Dig RNA labeling kit (Boehringer
Mannheim, Sussex, UK). In situ hybridization was performed as described
previously (1) with minor modifications using an Omnislide programmable
in situ system (Hybaid, London, UK). Paraffin-embedded tissue sections
(6 µm) were dewaxed by treatment with xylene, treated with proteinase
K (250 µg/ml, 37°C for 40 min), and postfixed in 4%
paraformaldehyde. The sections were then covered with 50 µl
prehybridization mix (50% vol/vol fomamide; 5× SSC, 1×
Denhardt's reagent, 0.1 mg/ml heat-denaturated salmon sperm DNA, 10%
wt/vol dextran sulfate) for 30 min at 50°C, followed by 50 µl of
the same mixture containing the digoxigenin-labeled riboprobe. A glass
coverslip was applied. Hybridization was allowed to occur at 50°C
overnight. After hybridization, the sections were treated with
ribonuclease A to remove unbound probe and then were washed with
stringent conditions. The hybridized probe was detected by incubating
the section with antidigoxigenin antibody conjugated to alkaline
phosphatase, followed by the chromogen solution, nitroblue tetrazolium,
and 5-bromo-4-chloro-3-indolyl phosphate toluidinum. The slides were
then washed and counterstained, if required, with hematoxylin. Controls
run in parallel with each experiment included tissue sections that were
1) incubated in hybridization mix
without probe added and 2)
hybridized in identical fashion with the digoxigenin-labeled sense
riboprobe. None of the control sections showed staining under the
conditions used for these experiments.
 |
RESULTS |
Guinea pig SP-A is highly conserved with other species
and is expressed specifically within lung tissue.
Screening 400,000 pfu of a newborn guinea pig lung cDNA library with a
full-length human SP-A cDNA probe resulted in the isolation of 10 individual overlapping cDNA clones. Sequencing and restriction
digestion suggested that all were derived from the same mRNA species
(results not shown). The longest of these clones was sequenced in both directions and was found to consist of 1,839 bp (Fig.
1) with a single open reading frame from
position 55 to 798, coding for a protein of 248 amino acids. As
expected, alignment of the nucleotide sequence with those of the two
human and baboon cDNAs and the single rabbit, rat, mouse, and dog cDNAs
showed that guinea pig SP-A has a high degree of sequence conservation
(results not shown). Comparison of the derived amino acid sequence of
guinea pig SP-A with those of the two human, two baboon, rabbit, rat,
and mouse proteins confirmed the high degree of sequence similarity
ranging between 68.8% (baboon SP-A2) and 74.1% (mouse SP-A; Fig.
2). Using the full-length SP-A cDNA as a
probe on Northern blots of total RNA isolated from heart, kidney,
liver, lung, and spleen, we confirmed that, as expected, guinea pig
SP-A is expressed exclusively in lung tissue. Two specific transcripts
were detected (Fig. 3,
top, lanes
7 and 8) in the lung
samples, with the most abundant transcript having the appropriate size
for the full-length cDNA. It is unclear if the larger transcript
represents a differentially spliced or polyadenylated mRNA species, and
we have not detected any clear differential expression of the two
transcripts under any conditions (results not shown).

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Fig. 1.
Nucleotide and derived amino acid sequences of guinea pig surfactant
protein (SP) A. Full-length cDNA clone of guinea pig SP-A was sequenced
as described in MATERIALS AND METHODS. (GenBank accession
number for this clone is U40869.) Derived amino acid sequence was
obtained from PC/Gene databases. Coding sequence is between 55 and 798 nucleotides. Regions of Gly-X-Y repeats are in bold type. Putative
glycosylation site is shown underlined in italics.
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Fig. 2.
Alignments of guinea pig SP-A with other SP-A proteins. Alignment of
guinea pig SP-A (GP) protein with human SP-A1 (HU1), human SP-A2 (HU2),
rat (RT), mouse (MO), rabbit (RB), baboon SP-A1 (B1), baboon SP-A2
(B2), and dog (DO) proteins. Asterisk (*) in guinea pig sequence
indicates a gap, and minus ( ) indicates conservation of the
amino acid. Numbers refer to the number of the amino acids.
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Fig. 3.
Tissue-specific expression of SP-A mRNA in adolescent guinea pig.
Samples of total RNA (10 µg/lane) from 2 adolescent guinea pig hearts
(lanes 1 and
2), kidneys (lanes
3 and 4), livers
(lanes 5 and
6), lungs (lanes
7 and 8), and
spleens (lanes 9 and
10) were electrophoresed in 1%
agarose gels as described in MATERIALS AND METHODS and were
hybridized with 32P-labeled SP-A
cDNA probe (top). Blot was
rehybridized with probe to guinea pig catalase (CAT;
bottom) to confirm the existence of
total RNA samples in each lane.
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Expression of guinea pig SP-A is confined to the
alveolar epithelium. To identify the cellular sites of
SP-A expression in guinea pig lung, we performed a series of in situ
hybridization studies with sections of lungs from 60-day-old adolescent
animals. SP-A mRNA distribution within a representative section of lung tissue is shown in Fig.
4A. SP-A
expression is seen exclusively within the presumptive type II cells of
the lung parenchyma and is not found in cells of the bronchiolar
epithelium, blood vessels, or pulmonary interstitium (Fig.
4A). Repeated analysis of multiple sections from four individual animals obtained from different matings
revealed identical results (results not shown). As this finding is at
odds with the expression pattern seen in other species (3, 10, 11, 28)
and to ensure that we could detect mRNA hybridization in bronchiolar
epithelial cells in similar sections, we hybridized additional sections
with a probe to guinea pig SP-B. In direct contrast to the expression
pattern seen with SP-A, SP-B mRNA is readily detected in both cellular
compartments (Fig. 4B). The
specificity of the hybridization reactions is shown by the lack of
signal in sections hybridized with a sense SP-A probe (Fig.
4C), and sections hybridized in the
absense of probe were also consistently negative.

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Fig. 4.
Expression of SP-A in guinea pig lung is confined to cells of the
alveolar epithelium. Tissue sections from adolescent guinea pig lungs
were hybridized with antisense guinea pig SP-A
(A), antisense guinea pig SP-B
(B), or sense guinea pig SP-A
(C) riboprobes as described in
MATERIALS AND METHODS. Representative views clearly show
expression of SP-A mRNA within the alveolar epithelium but not in the
bronchiolar epithelial cells (arrowheads in
A), whereas SP-B mRNA is found in
both alveolar and bronchiolar epithelial cells
(B). Sections hybridized with sense
SP-A probes were negative for signal
(C). Lowercase b in the lumen
identifies the bronchiolar region in each view.
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 |
DISCUSSION |
When compared with other species, guinea pig SP-A is highly conserved
at both the nucleotide and the amino acid levels. The derived amino
acid sequence of SP-A contains two distinct domains, the
NH2-terminal one-third of the
protein is collagen-like, whereas the COOH-terminal two-thirds has the
properties of a lectin (6). Additionally, the
NH2-terminal region contains a
nonconserverd signal peptide of 20 amino acids. The collagen-like
domain is composed of 24 Gly-X-Y repeats (where Y is frequently
proline; 13 from 24) and is interrupted one time between the 13th and
14th Gly-X-Y repeat with an additional proline at the 66th amino acid. SP-A from rat, mouse, rabbit, and dog also have the same number of
Gly-X-Y repeats (20). Interestingly, all of these species appear to
possess only a single SP-A gene product. In contrast, both in humans
and baboons, which express two highly related SP-A genes (15, 20),
there are only 23 Gly-X-Y repeats, with the substituted Gly after the
13th triplet being replaced in all four sequences with a Cys. A
tentative conclusion from our sequence analysis is that the guinea pig
posesses only a single SP-A gene. This conclusion is supported by the
observation that all of the clones identified in the library screen had
identical sequence over the regions studied. Definitive poof awaits
more detailed analysis by Southern blotting and genomic cloning. The
NH2-terminal portion of the
collagen domain, containing 13 Gly-X-Y repeats, is highly conserved
compared with the second region. The four functionally important Cys
residues found in the lectin domain (6) are also conserved in all
species.
The lack of SP-A mRNA in the bronchiolar epithelium, as shown by the in
situ hybridization studies, is unexpected in light of previous
observations. It is generally considered that SP-A is expressed in type
II cells (3, 10, 11, 17, 28). Studies in a number of species, including
humans, rats, mice, rabbits, and baboons, have also shown significant
expression of SP-A in the bronchiolar region of the lung (3, 10, 11, 28), although initial studies of SP-A mRNA expression in human bronchiolar epithelial cells proved negative (17). We are confident that our results represent a true lack of expression in these cells for
the following reasons. First, in situ hybridization performed using similar tissue sections and a probe to guinea pig SP-B
resulted in a marked level of expression within the bronchiolar epithelium. This finding suggests that the lack of signal in the sections hybridized with the SP-A was not due to technical problems associated with the detection of transcripts within this epithelium. Second, we have been unable to detect SP-A signal in multiple sections
from different developmental stages [including
days 35, 50,
60, and
65 of gestation (normal term = 68 days), term, and 10 days postpartum, results not shown],
suggesting that the lack of expression seen is not the result of a
temporal difference in SP-A transcript expression in adolescent guinea
pig lung compared with the fetal lung but rather that it reflects a
true lack of expression of SP-A mRNA within the bronchiolar epithelium.
The importance of this difference in expression of SP-A in guinea pig
lung compared with other species is unclear. It might be expected that
any localized reduction of SP-A protein secretion into the bronchiolar
lining fluid would be compensated for by the SP-A synthesized and
secreted by the cells of the alveolar epithelium.
The lack of expression of SP-A in the bronchiolar epithelial cells of
the guinea pig lung may, however, provide us with a useful model system
for the study of the transcriptional regulation of SP genes. The
expression of SP genes is regulated by a number of hormones and
cytokines (15, 18), and the molecular pathways governing their temporal
and spatial expression have begun to be elucidated (7, 27). Recently, a
number of studies have implicated the lung and thyroid-enriched
homeodomain transcription factor, thyroid transcription factor 1 (TITF-1), acting through binding sites located in the proximal
promoter, as a potent activator of SP-A gene expression (2, 27).
Studies of the cellular sites of expression of the SP genes and TITF-1
have shown that there is close overlap in expression profiles, with
both proteins being expressed in cells of the bronchiolar epithelium as
well as parenchymal alveolar type II cells (22, 31), suggesting that
TITF-1 expression may be necessary but not sufficient for expression of
SP-A. Our preliminary studies have identified TITF-1 expression in both
cellular compartments of the guinea pig lung (results not shown), which
further supports this contention. Additional studies are required to
directly compare the temporal and spatial expression patterns of SP and
TITF-1 gene expression within the guinea pig lung.
 |
ACKNOWLEDGEMENTS |
We are grateful to Dr. Tyler White for the gift of the human
surfactant protein A (SP-A) cDNA and to Tom Korfhagen and Erika Crouch
for helpful discussions on the localization of SP-A.
 |
FOOTNOTES |
These studies were supported in part by a generous donation from the
trustees of the estate of the late Leopold Muller, by the Department of
Health (United Kingdom), and by the K. C. Wong Education Foundation
(Hong Kong).
Address for reprint requests: C. D. Bingle, Section of Respiratory
Medicine, The University of Sheffield Medical School, Sheffield S10
2RX, UK.
Received 24 March 1997; accepted in final form 21 July 1997.
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REFERENCES |
1.
Bingle, C. D.,
B. P. Hackett,
M. Moxley,
W. Longmore,
and
J. D. Gitlin.
Role of hepatocyte nuclear factor 3
and hepatocyte nuclear factor 3
in Clara cell secretory protein gene expression in the bronchiolar epithelium.
Biochem. J.
308:
197-202,
1995[Medline].
2.
Bruno, M. D.,
R. J. Bohinski,
K. M. Huelsman,
J. A. Whitsett,
and
T. R. Korfhagen.
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].
3.
Coalson, J. J.,
R. J. King,
F. Yang,
V. Winter,
J. A. Whitsett,
R. A. deLemos,
and
S. R. Seider.
SP-A deficiency in primate model of bronchopulmonary dysplasia with infection. In situ mRNA and immunostaining.
Am. J. Respir. Crit. Care Med.
151:
854-866,
1995[Abstract].
4.
Farrell, P. M,
and
M. E. Avery.
Hyaline membrane disease.
Am. Rev. Respir. Dis.
111:
657-688,
1975[Medline].
5.
Floros, J,
and
A. M. Karinch.
Human SP-A: then and now.
Am. J. Physiol.
268 (Lung Cell. Mol. Physiol. 12):
L162-L165,
1995[Abstract/Free Full Text].
6.
Haagsman, H. P.
Surfactant proteins A and D.
Biochem. Soc. Trans.
22:
100-106,
1994[Medline].
7.
Hackett, B. P.,
C. D. Bingle,
and
J. D. Gitlin.
Mechanisms of gene expression and cell fate determination in the developing pulmonary epithelium.
Annu. Rev. Physiol.
58:
51-71,
1996[Medline].
8.
Kelly, F. J.,
G. M. Rickett,
A. N. Hunt,
G. I. Town,
S. T. Holgate,
and
A. D. Postle.
Biochemical maturation of the guinea pig lung and survival following premature delivery.
Int. J. Biochem.
23:
467-471,
1991[Medline].
9.
Kelly, F. J.,
G. I. Town,
G. J. Phillips,
S. T. Holgate,
W. R. Roche,
and
A. D. Postle.
The pre-term guinea pig. A model for the study of neonatal lung disease.
Clin. Sci. (Lond.)
81:
439-446,
1991[Medline].
10.
Khoor, A.,
M. E. Gray,
W. M. Hull,
J. A. Whitsett,
and
M. T. Stahlman.
Developmental expression of SP-A and SP-A mRNA in proximal and distal respiratory epithelium in human fetus and newborn.
J. Histochem. Cytochem.
41:
1311-1319,
1993[Abstract/Free Full Text].
11.
Korfhagen, T. R.,
M. D. Bruno,
S. W. Glasser,
P. J. Ciraolo,
J. A. Whitsett,
D. L. Lattier,
K. A. Wikenheiser,
and
J. C. Clark.
Murine pulmonary surfactant SP-A gene
cloning, sequence, and transcriptional activity.
Am. J. Physiol.
263 (Lung Cell. Mol. Physiol. 7):
L546-L554,
1992[Abstract/Free Full Text].
12.
Korfhagen, T. R.,
M. D. Bruno,
G. F. Ross,
K. M. Huelsman,
M. Ikegami,
A. H. Jobe,
S. E. Wert,
B. R. Stripp,
R. E Morris,
S. W. Glasser,
C. J. Bachurski,
H. S. Iwamoto,
and
J. A. Whitsett.
Altered surfactant function and structure in SP-A gene targeted mice.
Proc. Natl. Acad. Sci. USA
93:
9594-9599,
1996[Abstract/Free Full Text].
13.
Kremlev, S. G,
and
D. S. Phelps.
Surfactant protein A stimulation of inflammatory cytokine and immunoglobulin production.
Am. J. Physiol.
267 (Lung Cell. Mol. Physiol. 11):
L712-L719,
1994[Abstract/Free Full Text].
14.
Kuroki, Y,
and
D. R. Voelker.
Pulmonary surfactant proteins.
J. Biol. Chem.
269:
25943-25946,
1994[Free Full Text].
15.
McCormik, S. M.,
and
C. R. Mendelson.
Human SP-A1 and SP-A2 genes are differentiallly regulated during development and by cAMP and glucocorticoids.
Am. J. Physiol.
266 (Lung Cell. Mol. Physiol. 10):
L367-L374,
1994[Abstract/Free Full Text].
16.
Mendelson, C. R.,
J. L. Alcorn,
and
E. Gao.
The pulmonary surfactant protein genes and their regulation in fetal lung.
Semin. Perinatol.
17:
223-232,
1993[Medline].
17.
Phelps, D. S.,
and
J. Floros.
Localization of surfactant protein synthesis in human lung by in situ hybridization.
Am. Rev. Respir. Dis.
137:
939-942,
1988[Medline].
18.
Pryhuber, G. S.,
S. L. Shurch,
T. Kroft,
A. Panchal,
and
J. A. Whitsett.
3'-Untranslated region of SP-B mRNA mediated inhibitory effects of TPA and TNF-
on SP-B expression.
Am. J. Physiol.
267 (Lung Cell. Mol. Physiol. 11):
L16-L24,
1994[Abstract/Free Full Text].
19.
Rooney, S. A.,
S. L. Young,
and
C. R. Mendelson.
Molecular and cellular processing of lung surfactant.
FASEB J.
8:
957-967,
1994[Abstract/Free Full Text].
20.
Seidner, S. R.,
M. E. Smith,
and
C. R. Mendelson.
Developmental and hormonal regulation of SP-A gene expression in baboon fetal lung.
Am. J. Physiol.
271 (Lung Cell. Mol. Physiol. 15):
L609-L616,
1996[Abstract/Free Full Text].
21.
Sherman, M. P.,
and
T. Ganz.
Host defense in pulmonary alveoli.
Annu. Rev. Physiol.
54:
331-350,
1992[Medline].
22.
Stahlman, M. T.,
M. E. Gray,
and
J. A. Whitsett.
Expression of thyroid transcription factor-1 (TTF-1) in fetal and neonatal human lung.
J. Histochem. Cytochem.
44:
673-678,
1996[Abstract/Free Full Text].
23.
Suzuki, Y.,
Y. Fujita,
and
K. Kogishi.
Reconstitution of tubular myelin from synthetic lipids and proteins associated with pig pulmonary surfactant.
Am. Rev. Respir. Dis.
17:
439-443,
1989.
24.
Tenner, A. J.,
S. L. Robinson,
J. Borchelt,
and
J. R. Wright.
Human pulmonary surfactant protein (SP-A) a protein structurally homologous to C1q, can enhance FcR- and CR1-mediated phagocytosis.
J. Biol. Chem.
264:
13923-13928,
1989[Abstract/Free Full Text].
25.
Weissbach, S.,
A. Neuendank,
M. Petterson,
T. Schaberg,
and
U. Pison.
Surfactant protein A modulates release of reactive oxygen species from alveolar macrophages.
Am. J. Physiol.
267 (Lung Cell. Mol. Physiol. 11):
L660-L666,
1994[Abstract/Free Full Text].
26.
White, R. T.,
D. Damm,
J. Miller,
K. Spratt,
J. Schilling,
S. Hawgood,
B. Benson,
and
B. Cordell.
Isolation and characterization of the human pulmonary surfactant apoprotein gene.
Nature
317:
361-363,
1985[Medline].
27.
Whitsett, J. A.,
and
T. R. Korfhagan.
Regulation of gene transcription in respiratory epithelial cells.
Am. J. Respir. Cell Mol. Biol.
14:
118-120,
1996[Medline].
28.
Wohlford-Lenane, C. L.,
and
J. M. Snyder.
Localization of surfactant-associated proteins SP-A and SP-B mRNA in rabbit fetal lung tissue by in situ hybridization.
Am. J. Respir. Cell Mol. Biol.
7:
335-343,
1992[Medline].
29.
Wright, J. R.,
and
L. G. Dobbs.
Regulation of pulmonary surfactant secretion and clearance.
Annu. Rev. Physiol.
53:
395-414,
1991[Medline].
30.
Yuan, H. T.,
C. D. Bingle,
and
F. J. Kelly.
Differential patterns of antioxidant enzyme mRNA expression in guinea pig lung and liver during development.
Biochim. Biophys. Acta
1305:
163-171,
1996[Medline].
31.
Zhou, L.,
L. Lim,
R. H. Costa,
and
J. A. Whitsett.
Thyroid transcription factor-1, hepatocyte nuclear factor 3
, 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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