Center for Craniofacial Molecular Biology, Department of Pediatric Surgery, and Developmental Biology Program, Children's Hospital Los Angeles Research Institute, University of Southern California Schools of Dentistry and Medicine, Los Angeles, California 90033
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ABSTRACT |
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Laminins (LNs) are extracellular matrix
glycoproteins that are involved in cell adhesion, proliferation, and
differentiation. So far, 11 LN variants (LN1 to LN11) have been
described. In the lung, at least six LN variants have been identified.
However, only the role of LN1 has been characterized to any extent. In this study, we hypothesized that the LN2 variant may play a role during
lung development. We identified, by RT-PCR analysis, that the
2-chain mRNA of LN2 is
expressed during mouse lung development. LN2 adhesion assays were then
performed with cells from fetal mouse lung primary cultures. Our
results showed that a specific subpopulation of fetal lung cells that
expressed vimentin,
-smooth muscle actin, and desmin attached onto
LN2, whereas the cells that did not adhere to LN2 as well as the total
cell population were able to adhere readily on fibronectin. Cell
attachment onto LN2 was inhibited by EDTA. In addition, we
demonstrated, by RT-PCR and Western analysis, that the LN2-adherent
cells autoexpressed the
2-chain of LN2. In the late pseudoglandular
period, LN2 was localized by immunohistochemistry in the basement
membrane of airways and blood vessels and around mesenchymal
cells. We conclude that LN2 is expressed during lung development and
that a specific subpopulation of fetal lung mesenchymal cells
expressing a myofibroblastic phenotype can be selected by attachment to
LN2 in primary culture. These findings lead us to speculate that
LN2 may play a key role in the cell biology of myofibroblasts during
lung development.
merosin; lung development; mesenchymal cells; cell adhesion
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INTRODUCTION |
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LAMININS (LNs) are a family of extracellular matrix
(ECM) glycoproteins. They are composed of one central chain () and
two lateral chains (
and
) that are linked by disulfide bonds to form a cross-shaped molecule. The LN family is composed of 11 variants
(LN1 to LN11) (33), which result from the combination of different
chain isoforms. To date, five
-, three
-, and two
-chain
isoforms have been characterized. Their expression and distribution is
tissue specific.
In the lung, the identification of various chain isoforms of LN
(1,
2,
3,
1,
2,
3, and
1) suggests that at least six LN variants are present (2, 8, 12, 15, 35). The LN1 variant has been
extensively characterized during lung development (9, 18, 20). It is
involved in lung morphogenesis and lung epithelial cell polarization
(26, 31). However, the role and importance of the other LN variants
identified during lung development remain to be elucidated.
Specific domains localized in the different chain isoforms of LN1 play
specific roles during lung development. The cross region of the
1-chain of LN1 participates in
epithelial-mesenchymal interaction. The globular region of the
- and
-chains are involved in cell polarization. In addition, a fragment
containing the carboxy-terminal region, obtained after degradation of
LN1, participates in the in vitro formation of alveolar-like structures
(22, 27-29).
The LN2 (2,
1,
1) variant was originally
described as being specific to muscle cells, the placenta, and
peripheral nerves (10, 21). However, in recent studies (1, 4, 35), LN2 has also been identified in other tissues including the lung. Virtanen
et al. (35) have recently identified the
2-chain (molecular mass 300 kDa) of LN2 in both lung epithelial cells and smooth muscle cells during the pseudoglandular and canalicular stage of
embryonic human gestation. In addition, in patients with severe chronic
asthma, the
2-chain isoform of
LN2 was identified in the basement membrane of epithelial airways,
suggesting its participation in remodeling of the ECM (1).
In the present study, we hypothesized that the LN2 variant may be
expressed and play a role during fetal lung development. To test this
hypothesis, we identified the expression of the
2-chain isoform of LN2 during
mouse lung development using RT-PCR analysis. We determined that a
particular subpopulation of mesenchymal cells derived from primary
cultures of embryonic day (ED)
16 mouse embryos attach selectively to
LN2. This subpopulation of fetal lung cells expressed vimentin,
-smooth muscle actin, and desmin (VAD), cell markers characteristic
of VAD-type myofibroblasts (6, 7, 13, 17). In addition, we show that
this cell subpopulation autoexpressed LN2. Our data suggest that LN2
plays an important role during lung development by directing adherence
of a specific mesenchymal cell population with a myofibroblastic
phenotype.
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METHODS |
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Materials. SeaKem agarose
LE was purchased from Intermountain Scientific. RT-PCR kit was from
Perkin-Elmer (Foster City, CA). Trizol, 100-bp DNA ladder, LN1, LN2,
and fibronectin (FN) were obtained from GIBCO BRL (Gaithersburg, MD).
Antibody against 2-chain isoform was from Chemicon (Temecula, CA). Dulbecco's modified Eagle's
medium (DMEM); fetal bovine serum; penicillin-streptomycin; Triton
X-100; 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide
(thiazolyl blue; MTT); and antibodies against keratin (clone PCK-26),
vimentin (clone VIM-13),
-smooth muscle actin (clone 1A4), and
desmin were purchased from Sigma (St. Louis, MO). The antibody directed
against smooth muscle myosin heavy chain was kindly provided by Dr. M. Schwartz (Children's Hospital Los Angeles, CA).
RT-PCR reactions. For PCR
amplification, total RNA was extracted from ED12 to ED18 mouse lung
tissue or ED16 primary cell cultures according to the manufacturer's
instruction (Trizol, GIBCO BRL). To synthesize cDNA, 1 µg of total
RNA was incubated in 20 µl of reaction buffer (5 mM
MgCl2, 50 mM KCl, and 10 mM Tris · HCl, pH 8.3) with 2.5 µM
oligo(dT)16 primer and 2.5 U/µl of murine leukemia virus reverse transcriptase that was purchased as an
RT-PCR kit (Perkin-Elmer). The RT reaction was carried out in one cycle
at 42°C for 20 min and 99°C for 5 min. The PCR reaction was
carried out in three steps as follows: 94°C for 90 s (1 cycle); 94°C for 35 s, 60°C for 35 s, and 72°C for 35 s (32 cycles); and 72°C for 6 min and 4°C for 5 min (1 cycle). In
some experiments, the second step consisted of 22 cycles, but the
results were similar. PCR analysis was performed with
LN-1 primers: sense,
5'-AGTCCTTCAGCGCTCGTCCC-3'; antisense,
5'-GATCGACGCCGCTTGTTTCC-3'; size product 521 bp.
LN-
2 primers were sense
5'-CGACCGGATGCTGAAGGAAC-3' and antisense
5'-CCTCGGACATTGGTGGCAAC-3', size product 445 bp. The mouse
-actin
primers, used as controls, were previously described by Kaartinen et
al. (16): sense, 5'-GTGGGCCGGTCTAGGCACCA-3'; antisense,
5'-GGTTGGCCTTAGGGTTCAGG-3'; size product 246 bp.
Primary cell cultures. Cells were isolated from ED16 mouse lungs as described by Schuger et al. (26), with some minor modifications. In brief, ED16 mice embryos were removed from the uteri under sterile conditions. The lungs were dissected out and placed in a petri dish containing 10 ml of Hanks' balanced salt solution with 100 U/ml of penicillin and 100 µg/ml of streptomycin. The lungs were cut into small pieces, and the medium was exchanged after two washes with Hanks' balanced salt solution containing 0.1% trypsin-EDTA and incubated at 37°C for 20-30 min. Isolated cells were filtered through a 100-µm nylon mesh. The cells were pelleted by centrifugation and resuspended in DMEM-10% fetal bovine serum containing 100 U/ml of penicillin and 100 µg/ml of streptomycin. The cells were plated in a 75-cm2 tissue culture flask and incubated for 1 h at 37°C. Nonattached cells were washed out. The attached cells were grown for 24 h at 37°C in a 5% CO2 atmosphere. Immunohistochemical analysis of these primary cell cultures revealed them to be principally mesenchymal-type cells containing <1% of keratin-positive cells (data not shown), a specific cell marker of epithelial cells.
Cell adhesion assays. Culture plates with 96 wells or 35-mm petri dishes were coated with different concentrations of LN1, LN2, and FN. The coated plates were incubated overnight at 4°C. The wells were saturated with 2 mg/ml of BSA for 2 h at room temperature. Fetal lung cells from primary cultures were washed with PBS, pH 7.5, containing 5 mM glucose and 2 mM EDTA. The cells were detached with 0.05% trypsin-EDTA and resuspended in DMEM containing 2 mg/ml of BSA and 1 mM MgCl2. The total cell suspensions were centrifuged and resuspended in DMEM. Aliquots containing 50,000 cells/50 µl DMEM were seeded in each well of the 96-well plates. In the experiments performed with the 35-mm petri dishes, aliquots of 200,000 cells/ml were seeded. Cells were incubated for 60 min at 37°C in a 5% CO2 atmosphere. Unattached cells were removed by aspiration. In some experiments, unattached cells were replated over FN- or LN2-coated dishes. Adherent cells were washed two times with DMEM and then incubated in DMEM containing 1 mg/ml of MTT for 60 min at 37°C in a 5% CO2 atmosphere to be quantified. Color absorbance derived from the metabolized MTT by viable cells was determined at 560 nm in an MRX microplate reader (Dynatech Laboratories). The number of cells adhered onto LN2 and LN1 was calculated from a standard curve prepared with cells attached onto FN-coated wells (1 µg FN/well) and incubated with MTT. The total number of cells plated onto FN adhered to this substrate. Experiments were performed in at least triplicate, and values are means ± SD. Viability of the cells in all experiments was checked by the exclusion of trypan blue, and only cell cultures containing >95% of viable cells were used.
Western analysis. Cell cultures were washed two times with PBS solution. The cells were incubated with 0.1% Triton X-100 for 10 min in the presence of a proteinase inhibitor cocktail. The cell extract was recovered and centrifuged at 10,000 g for 10 min. The supernatant was recovered, and SDS solution was added to a final concentration of 2%. Protein determination was performed with the bicinchoninic acid protein assay (Pierce, Rockford, IL). Equal amounts of cell extract proteins and commercially purified LN1 and LN2 were separated by SDS-polyacrylamide gel electrophoresis. Separated proteins were electrotransferred onto nitrocellulose paper. Blotted proteins were immunoreacted with the respective primary antibodies. Bands were revealed with the appropriate peroxidase-conjugated secondary antibody (Bio-Rad, Richmond, CA) and stained with a diaminobenzidine substrate kit (Pierce).
Immunohistochemical analysis. Cells
and fetal lung tissue were fixed and processed for immunohistochemistry
following the protocol indicated in the Histomouse SP kit (Zymed
Laboratories). The primary antibodies used were anti-cytokeratin
(1:500; Sigma), anti-2-chain
isoform of LN2 (1:40; Chemicon), anti-vimentin (1:50; Sigma),
anti-
-smooth muscle actin (1:1,000, Sigma), anti-desmin (1:300;
Sigma), and anti-
-smooth muscle myosin heavy chain (1:300; provided
by Dr. M. Schwartz). After subsequent washing of the samples in PBS,
the secondary antibody (biotinylated antibody; Zymed Laboratories) was
applied for 30 min. Finally, the antigen immunodetection was visualized
after incubation of the streptavidin-peroxidase substrate. Tissues and
cells were counterstained with hematoxylin and covered with a
coverslip. The samples were examined and photographed with an Olympus
BH2 microscope.
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RESULTS |
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2-Chain isoform of LN2 is
expressed during fetal mouse lung development.
To determine whether LN2 was expressed during mouse lung development,
we identified the expression of the
2-chain isoform of LN2 by
RT-PCR analysis. We designed specific primers for the mouse
2-chain isoform of LN2 and the
1-chain isoform of LN1. We used
published primers of
-actin as a control. Total RNA extracted from
ED12 to ED18 fetal lung tissue was reverse transcribed, and cDNA was
used for the PCR reactions. As shown in Fig.
1, the amplified products of expected size
for the
2-chain (445 bp) and
1-chain (521 bp) isoform of LN
were identified during fetal mouse lung development from ED12 to ED18.
No amplified products were observed in samples incubated without
reverse transcriptase. The identification of the
2- and
1-chain products indicated that
LN2 and LN1, respectively, are expressed during lung development.
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DISCUSSION |
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In the present report, we have shown that
2-chain mRNA of LN2 is
expressed in embryonic lung tissue, suggesting that LN2 may play a
biological role during mouse lung development. The expression of LN2
was originally reported to be specific to the basement membrane of
striated muscle, trophoblasts, and peripheral nerves (10, 21). However,
our results presented here, together with recent data from other
laboratories (4, 35), indicate that LN2 has a more general
distribution. On the other hand, one report (33) has
indicated that LN2, together with LN1, may also contribute in the
assembly of the basement membrane, indicating that LN2 may actively
participate in the structural organization of the ECM.
Our results obtained by PCR suggest that the pattern of expression of
the 2-chain during mouse lung
development is different from that of the
1-chain. This expression
pattern was observed in all the experiments performed during the
present work. In addition, our results indicated that LN2 is expressed
by fetal lung cells from the beginning of lung development. Previous
reports (10, 21) have shown that LN2 is expressed in earlier embryonic
stages that precede lung development.
A recent study (35) also indicated a distinct expression pattern and
distribution of the 2-chain
during human lung development. In the human study, the
2-chain of LN2 was localized
principally in the basement membrane of bronchial epithelial cells
during the pseudoglandular stage of lung development, whereas in the canalicular stage, the
2-chain
was localized along peribronchial smooth muscle cells. These data
suggest that LN2 may play a role during bronchial smooth muscle cell
development in human embryonic lung.
A previous study (1) has further indicated that LN2 is expressed in
adult patients with severe asthma but not in healthy patients,
suggesting that LN2 may play a biological role in lung ECM remodeling.
LN2 has also been implicated in congenital muscular dystrophy (36, 39);
a partial mutation in the
2-chain gene is a major cause
of this disease (32). LN2 null mutant animals die at an early age.
However, it is not known whether patients or animals with LN2-related
disease have abnormal lung myofibroblasts.
In the present report, we determined for the first time a specific biological role for LN2 as a selective cell-adhesive substrate for a specific subpopulation of fetal lung mesenchymal cells. In addition, we demonstrated a differential pattern of cell adhesion for mesenchymal cells between LN2 and LN1. This study was performed with primary cell cultures derived from ED16 lungs. This embryonic day corresponds to the pseudoglandular stage in mouse lung development. The best yield of isolated mesenchymal cells that adhere to LN2 was obtained on ED16.
Our results further support the hypothesis that each LN variant may
play a specific role during lung development. Both LN1 and LN2 contain
the 1- and
1-chains but differ in the
-chain. Therefore, the
-chain may contribute directly to the
differences in adhesive properties. There is only 46% homology between
mouse LN
2- and
1-chains (2). Several domains
in the
1-chain of LN1 with
ascribed cell-adhesive properties, such as RGD and SIKVAV sequences,
are not found in the
2-chain
(2). Differential attachment to LN2 in comparison to LN1 suggests the
presence of specific receptors for the mouse
2-chain in fetal lung
mesenchymal cells.
LN1 (1,
1,
1) was the first laminin
purified and characterized (34). Its expression has been demonstrated
to be crucial for the early progression of embryonic development.
During lung development, LN1 is expressed principally by epithelial
cells (35). In addition, LN1 promotes the organotypic rearrangement of
isolated mesenchymal and epithelial cells from fetal mouse lung when
cultured together (26, 31). In particular, the
1-chain (400 kDa) of LN1 was
observed to be widely distributed in pulmonary basal membranes of lung
tissue during human fetal development (20, 35). In addition, the LN1
variant has been described to be a preferential substrate for
epithelial cells (3). The subpopulation of cells that attach to LN2
expressed vimentin, a protein found in fibroblastic cells but not in
keratin, a specific marker of epithelial cells. We also noted that a
majority of these cells expressed
-smooth muscle actin and desmin,
two intracytoplasmic proteins considered to be phenotypic markers of
myofibroblasts and/or smooth muscle cells (6, 7, 13, 17). Thus
our observations indicate for the first time that LN2 may be involved in the attachment of a specific subpopulation of fetal lung mesenchymal cells that bear a myofibroblastic phenotype.
In vivo, the concept of fibroblast heterogeneity is now well accepted.
It is suggested that fibroblast populations are modulated during
development to produce a heterogeneous phenotypic population in
different organs (6, 7, 17, 24). Thus fibroblastic cells are relatively
undifferentiated and can assume a particular phenotype according to
physiological needs and/or microenviromental stimuli (24, 25).
Cultured fibroblasts may also express different phenotypic features.
When grown in vitro, subpopulations of fibroblasts derived from normal
tissue acquire several phenotypic features of myofibroblasts. This
observation has been indicated by different groups (6, 7, 24). Among
the smooth muscle cell markers expressed by myofibroblastic
populations, -smooth muscle actin is the most common, followed by
desmin (6). Smooth muscle myosin heavy chain expression is observed to
a lesser extent, and it is principally attributed to be a specific
marker of smooth muscle cells (6, 13). Our results showed that the
LN2-adherent subpopulation consisted of ~90% of cells expressing
-smooth muscle actin and desmin, and only a small number of cells (9 ± 4.8%) were observed to express smooth muscle myosin heavy chain
(Fig. 5). Myofibroblastic cells expressing vimentin, desmin, and
-smooth muscle actin have been classified as VAD type (6). Our
results suggest that the subpopulation of LN2-adherent cells reported
herein correspond principally to VAD-type myofibroblasts. Although we
observed that almost all mesenchymal cells expressed LN2 (Fig. 5), the
selective attachment of the subpopulation of myofibroblasts to LN2
suggests the presence of specific LN2 cell membrane receptors for this substrate in this particular cell subpopulation. In contrast, we
observed that the cell population unable to attach to LN2 was, however,
able to attach to FN, indicating that the latter cell population may
not bear the specific receptors necessary to attach to LN2. Thus our
results strongly support the existence of fibroblast heterogeneity
during lung development and suggest that the LN2-adherent cell
subpopulation may play an important role in pathological states such as
asthma in which an elevated expression of LN2 and cell-matrix
remodeling occurs (1).
The autoexpression of LN2 in the subpopulation of cells that adhered to
LN2 was corroborated by RT-PCR and Western analysis. A monoclonal
antibody to the 2-chain
detected a single 70-kDa band in the lung cell subpopulation that
attached to LN2. This was somewhat lower than the molecular mass (80 kDa) observed with human
2-chain. However, this
difference has also been observed by another group (11) and may reflect
species differences in the relative glycosylation of the respective
molecules.
In a recent publication, Schuger et al. (30) indicated that an antibody
directed against the 1-chain of
LN1 was able to modify the phenotype of smooth muscle cells in
embryonic lung explants and decreased the expression of desmin.
However, an antibody directed against the
2-chain did not produce any
effects. These results, together with our data, suggest that LN2 may
principally play a biological role as a cell adhesion substrate for a
specific subpopulation of mesenchymal cells. Preliminary studies in our laboratory indicate that growth factors, together with this LN2-cell interaction, may modulate the proliferation and migration of this cell
subpopulation. In contrast, LN1 may be involved in controlling differentiated cell functions and play a role as a preferential substrate for epithelial cells.
Several integrin and non-integrin receptors have been described for LN1
and LN2 (11). In the lung, the integrin receptors 3
1
and
6
1
bind LN1 (3, 19). However, the integrin receptors present in fetal lung
mesenchymal cells that bind LN2 are unknown. Integrin function is
dependent on divalent cations (23), and the presence of chelating
agents such as EDTA completely inhibits their function. Herein, we have
demonstrated that the attachment of fetal lung mesenchymal cells to LN2
can be abrogated by the presence of EDTA, suggesting the involvement of
an integrin receptor in the adhesion to LN2. A recent report (5) has
indicated that LN1 and LN2 are able to bind both
1
1-
and
2
1-integrins.
However, the differential adhesion pattern of mesenchymal cells to LN1 versus LN2 suggests the involvement of another type of integrin. We are currently isolating and characterizing membrane receptors derived from lung mesenchymal cells that bind LN2.
The RGD sequence domain found in FN and some ECM glycoproteins
interacts directly with integrins. In lung cells, the integrin 5
1
is the principal receptor for FN (3). Our results show that only a
subpopulation of fetal lung mesenchymal cells binds to LN2; meanwhile,
the cells that did not attach to LN2 can bind to FN, further suggesting
that specific receptors for LN2 may mediate selective adherence to LN2
versus FN.
Recent studies (14, 37) have identified the dystrophin-dystroglycan complex as a non-integrin receptor that binds LN2. However, the role of this receptor in the attachment of lung mesenchymal cells to LN2 remains to be characterized.
The presence of other variants of LN in the lung leads to the
speculation that each variant may have a specific role during lung
development, and this remains to be elucidated. The recent identification of the 3-chain
isoform of LN in lung (12) suggests that LN5, LN6, or LN7 may also be
present (33). The latter chain isoform has been localized in the
basement membrane of epithelial cells in human fetal lung (35). In
addition, the expression of the
2-chain isoform that forms part
of the variants LN3, LN4, and LN7 was demonstrated in alveolar type II
cells during development of rabbit lung (9). Its distribution was
localized in the basement membrane of airways and arterial blood
vessels. The presence of the
4-chain that forms part of LN8
has also been observed to be highly expressed in lung tissue (15). The
LN2 immunostaining observed in fetal lung tissue agrees with previous
observations, indicating that LN2 is expressed by mesenchymal cells.
To our knowledge, this is the first report indicating that LN2 is an adhesive substrate for fetal lung myofibroblasts. In the past, several studies (3, 38) have used either individual or mixed ECM proteins such as Matrigel or Gelfoam as cell substrates. However, the cell membrane receptors involved in the attachment to these substrates may differ from those used in the cell attachment to LN2.
In conclusion, we have shown that LN2 is present in a specific temporospatial distribution in embryonic mouse lung and is involved in the differential attachment of a subpopulation of fetal lung mesenchymal cells that express a myofibroblastic phenotype. We speculate that LN2-cell interaction may be involved in the migration, distribution, and proliferation of this LN2-adherent cell population during mouse lung development.
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ACKNOWLEDGEMENTS |
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We thank Pei Jia Chen and Norman W. Lautsch for technical advice and Valentino Santos for photographic assistance.
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FOOTNOTES |
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This work was supported by National Heart, Lung, and Blood Institute Grants HL-44977 and HL-44060.
Address for reprint requests: D. Warburton, Center for Craniofacial Molecular Biology, School of Dentistry, Univ. of Southern California, 2250 Alcazar St., Los Angeles, CA 90033.
Received 10 October 1997; accepted in final form 29 May 1998.
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REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
1.
Altraja, A.,
A. Laitinen,
I. Virtanen,
M. Kampe,
B. G. Simonsson,
S. Karlsson,
L. Hakansson,
P. Venge,
H. Sillastu,
and
L. A. Laitinen.
Expression of laminins in the airways in various types of asthmatic patients: a morphometric study.
Am. J. Respir. Cell Mol. Biol.
15:
482-488,
1996[Abstract].
2.
Bernier, S. M.,
A. Utani,
S. Sugiyama,
T. Doi,
C. Polistinas,
and
Y. Yamada.
Cloning and expression of laminin 2 chain (M-chain) in the mouse.
Matrix Biol.
14:
447-455,
1994.
3.
Caniggia, I.,
J. Liu,
R. Han,
J. Wang,
A. K. Tanswell,
G. Laurie,
and
M. Post.
Identification of receptors binding fibronectin and laminin on fetal rat lung cells.
Am. J. Physiol.
270 (Lung Cell. Mol. Physiol. 14):
L459-L468,
1996
4.
Chang, A. C.,
S. Wadsworth,
and
J. E. Coligan.
Expression of merosin in the thymus and its interaction with thymocytes.
J. Immunol.
151:
1789-1799,
1993
5.
Colognato, H.,
M. MacCarrick,
J. J. O'Rear,
and
P. D. Yurchenco.
The laminin 2-chain short arm mediates cell adhesion through both
1
1 and
2
1 integrins.
J. Biol. Chem.
272:
29330-29336,
1997
6.
Desmouliere, A.,
and
G. Gabbiani.
Modulation of fibroblastic cytoskeletal features during pathological situations: the role of extracellular matrix and cytokines.
Cell Motil. Cytoskeleton
29:
195-203,
1994[Medline].
7.
Desmouliere, A.,
L. Rubbia-Brandt,
A. Abdiu,
T. Waltz,
A. Macieira-Coelho,
and
G. Gabbiani.
Alpha-smooth muscle actin is expressed in a subpopulation of cultured and cloned fibroblast and is modulated by gamma-interferon.
Exp. Cell Res.
201:
64-73,
1992[Medline].
8.
Durham, P. L.,
and
M. Snyder.
Characterization of 1,
1, and
1 laminin subunits during rabbit fetal lung development.
Dev. Dyn.
203:
408-421,
1995[Medline].
9.
Durham, P. L.,
and
M. Snyder.
Regulation of the 2 subunit chain of laminin in developing rabbit fetal lung tissue.
Differentiation
60:
229-243,
1996[Medline].
10.
Ehrig, K.,
I. Leivo,
W. S. Argraves,
E. Ruoslahti,
and
E. Engvall.
Merosin, a tissue-specific basement membrane protein, is a laminin-like protein.
Proc. Natl. Acad. Sci. USA
87:
3264-3268,
1990[Abstract].
11.
Ekblom, P.
Receptors for laminins during epithelial morphogenesis.
Curr. Opin. Cell Biol.
8:
700-706,
1996[Medline].
12.
Galliano, M.,
D. Aberdam,
A. Aguzzi,
J. Ortonne,
and
G. Meneguzzi.
Cloning and complete primary structure of the mouse 3 chain.
J. Biol. Chem.
270:
21821-21826,
1995.
13.
Halayko, A. J.,
H. Salari,
X. Ma,
and
N. L. Stephens.
Markers of airway smooth muscle phenotype.
Am. J. Physiol.
270 (Lung Cell. Mol. Physiol. 14):
L1040-L1051,
1996
14.
Henry, M. D.,
and
K. P. Campbell.
Dystroglycan: an extracellular matrix receptor linked to the cytoskeleton.
Curr. Opin. Cell Biol.
8:
625-631,
1996[Medline].
15.
Iivanainen, A.,
K. Sainio,
H. Sariola,
and
K. Tryggvason.
Primary structure and expression of a novel human laminin 4 chain.
FEBS Lett.
365:
183-188,
1995[Medline].
16.
Kaartinen, V.,
J. W. Voncken,
C. Shuler,
D. Warburton,
D. Bu,
N. Heisterkamp,
and
J. Groffen.
Abnormal lung development and cleft palate in mice lacking TGF-3 indicates defects of epithelial-mesenchymal interaction.
Nat. Genet.
11:
415-421,
1995[Medline].
17.
Kapanci, Y.,
and
G. Gabbiani.
Contractile cells in pulmonary alveolar tissue.
In: The Lung, Scientific Foundations (2nd ed.), edited by R. G. Crystal. New York: Raven, 1997, chapt. 48, p. 697-707.
18.
Klein, G.,
M. Ekblom,
L. Fecker,
R. Timpl,
and
P. Ekblom.
Differential expression of laminin A and B chains during development of embryonic organs.
Development
110:
823-837,
1990[Abstract].
19.
Kreidberg, J. A.,
M. J. Donovan,
S. L. Goldstein,
H. Rennke,
K. Shepherd,
R. C. Jones,
and
R. Jaenish.
Alpha 3 beta 1 integrin has a crucial role in kidney and lung organogenesis.
Development
122:
3537-3547,
1996
20.
Lallemand, A. V.,
S. M. Ruocco,
and
D. A. Gaillard.
Synthesis and expression of laminin during human fetal lung development.
Anat. Rec.
242:
233-241,
1995[Medline].
21.
Leivo, I.,
and
E. Engwall.
Merosin, a protein specific for basement membranes of Schawnn cells, striated muscle, and trophoblast, is expressed late in nerve and muscle development.
Proc. Natl. Acad. Sci. USA
85:
1544-1547,
1988[Abstract].
22.
Matter, M. L.,
and
G. W. Laurie.
A novel laminin E8 cell adhesion site required for lung alveolar formation in vitro.
J. Cell Biol.
124:
1083-1090,
1994[Abstract].
23.
Mould, A. P.
Getting integrins into shape: recent insights into how integrin activity is regulated by conformational changes.
J. Cell Sci.
109:
2613-2618,
1996
24.
Sappino, A. P.,
W. Schurch,
and
G. Gabbiani.
Differentiation repertoire of fibroblastic cells: expression of cytoskeletal proteins as marker of phenotypic modulation.
Lab. Invest.
63:
144-161,
1990[Medline].
25.
Schmitt-Graff, A.,
A. Desmouliere,
and
G. Gabbiani.
Heterogeneity of myofibroblast phenotypic features: an example of fibroblastic cell plasticity.
Virchows Arch.
425:
3-24,
1994[Medline].
26.
Schuger, L.,
S. O'Shea,
B. B. Nelson,
and
J. Varani.
Organotypic arrangement of mouse embryonic lung cells on a basement membrane extract: involvement of laminin.
Development
110:
1091-1099,
1990[Abstract].
27.
Schuger, L.,
A. P. N. Skubitz,
K. Gilbride,
R. Mandel,
and
L. He.
Laminin and heparan sulfate proteoglycan mediate epithelial cell polarization in organotypic cultures of embryonic lung cells: evidence implicating involvement of the inner globular region of laminin B1 chain and the heparan sulfate groups of heparan sulfate proteoglycan.
Dev. Biol.
179:
264-273,
1996[Medline].
28.
Schuger, L.,
A. P. N. Skubitz,
A. Morenas,
and
K. Gilbride.
Two separate domains of laminin promote lung organogenesis by different mechanisms of action.
Dev. Biol.
169:
520-532,
1995[Medline].
29.
Schuger, L.,
A. P. N. Skubitz,
K. S. O'Shea,
J. F. Chang,
and
J. Varani.
Identification of laminin domains involved in epithelial branching morphogenesis: effects of anti-laminin monoclonal antibodies on mouse embryonic lung development.
Dev. Biol.
146:
531-541,
1991[Medline].
30.
Schuger, L.,
A. P. N. Skubitz,
J. Zhang,
L. Sorokin,
and
L. He.
Laminin 1 chain synthesis in the mouse developing lung: requirement for epithelial-mesenchymal contact and possible role in bronchial smooth muscle development.
J. Cell Biol.
139:
553-562,
1997
31.
Schuger, L.,
J. Varani,
P. D. Killen,
A. P. N. Skubitz,
and
K. Gilbride.
Laminin expression in the mouse lung increases with development and stimulates spontaneous organotypic rearrangement of mixed lung cells.
Dev. Dyn.
195:
43-54,
1992[Medline].
32.
Sunada, Y.,
S. M. Bernier,
A. Utani,
Y. Yamada,
and
K. Campbell.
Identification of a novel mutant transcript of laminin 2 chain gene responsible for muscular dystrophy and dysmyelination in dy2j mice.
Hum. Mol. Genet.
4:
1055-1061,
1995[Abstract].
33.
Timpl, R.
Macromolecular organization of basement membranes.
Curr. Opin. Cell Biol.
8:
618-624,
1996[Medline].
34.
Timpl, R.,
H. Rohde,
P. G. Robey,
S. I. Rennard,
J. M. Foidart,
and
G. R. Martin.
Laminina glycoprotein from basement membranes.
J. Biol. Chem.
254:
9933-9942,
1979[Abstract].
35.
Virtanen, I.,
A. Laitinen,
T. Tani,
P. Paakko,
L. A. Laitinen,
R. E. Burgeson,
and
V. Lehto.
Differential expression of laminins and their integrin receptors in developing and adult human lung.
Am. J. Respir. Cell Mol. Biol.
15:
184-196,
1996[Abstract].
36.
Xu, H.,
P. Christmas,
X. Wu,
U. M. Wewer,
and
E. Engvall.
Defective muscle basement membrane and lack of M-laminin in the dystrophic dy/dy mouse.
Proc. Natl. Acad. Sci. USA
91:
5572-5576,
1994[Abstract].
37.
Yamada, H.,
A. Chiba,
T. Endo,
A. Kobata,
L. V. Anderson,
H. Hori,
H. Fukuta-Ohi,
I. Kanazawa,
K. P. Campbell,
T. Shimizu,
and
K. Matsumura.
Characterization of dystroglycan-laminin interaction in peripheral nerve.
J. Neurochem.
66:
1518-1524,
1996[Medline].
38.
Yoshida, S.,
E. Shiizu,
T. Ogura,
M. Takada,
and
S. Sone.
Stimulatory effect of reconstituted basement membrane components (matrigel) on the colony formation of a panel of human lung cancer cell lines in soft agar.
J. Cancer Res. Clin. Oncol.
123:
301-309,
1997[Medline].
39.
Zhang, X.,
R. Vuolteenaho,
and
K. Tryggvason.
Structure of the human laminin 2-chain gene (Lama2), which is affected in congenital muscular dystrophy.
J. Biol. Chem.
271:
27664-27669,
1996
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