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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
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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