Assembly of the exogenous extracellular matrix during basement membrane formation by alveolar epithelial cells in vitro.
We found that immortalized alveolar type II epithelial cells (SV40-T2 cells) that were cultured on dense fibrillar collagen supplemented with Matrigel gel formed a thin and continuous lamina densa beneath them. Immunohistochemical analysis of laminin-1, type IV collagen, entactin (nidogen) and perlecan in the culture indicated that all these components were integrated into a sheet structure of basement membrane beneath the cells. Analysis of the temporal and spatial distribution of the basement membrane macromolecules revealed that the initial deposits of laminin-1 and entactin were significantly greater in area in the presence of Matrigel. These globular deposits and the coarse mesh of basement membrane macromolecules developed into a flat membranous basement membrane. In the absence of Matrigel, the SV40-T2 cells failed to form a continuous lamina densa, and the deposits stayed in the coarse mesh. The major biotinylated Matrigel components that were integrated into the basement membrane were laminin-1 and entactin. Furthermore, SV40-T2 cells supplemented with exogenous laminin-1 alone as well as laminin-1 contaminated with entactin formed a continuous lamina densa. These results indicate that the laminin-1 and entactin supplied from the Matrigel were incorporated into a basement membrane beneath the SV40-T2 cells, and contributed to the formation of basement membrane. Therefore, we concluded that the alveolar epithelial cells synthesize laminin-1, entactin, type IV collagen, and perlecan, but that they also needed to assemble exogenous laminin-1 into the basement membrane to complete its formation in vitro.
Furuyama
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Environmental Health Sciences Division, National Institute for Environmental Studies, Tsukuba, Ibaraki 305-0053, Japan.
Mochitate
K
K
D000818:Animals; D001485:Basement Membrane / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D019921:Biotinylation; D002461:Cell Line, Transformed; D002472:Cell Transformation, Viral; D003094:Collagen / Q000502:physiology; D004338:Drug Combinations; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D005109:Extracellular Matrix / Q000502:physiology*; D007797:Laminin / Q000378:metabolism / Q000502:physiology; D008562:Membrane Glycoproteins / Q000378:metabolism; D011509:Proteoglycans / Q000502:physiology; D011650:Pulmonary Alveoli / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D013539:Simian virus 40 / Q000502:physiology
D004338:Drug Combinations; D007797:Laminin; D008562:Membrane Glycoproteins; D011509:Proteoglycans; C121346:laminin 1; C029967:nidogen; C059485:matrigel; D003094:Collagen