ISSN:
0021-9541
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
,
Medicine
Notes:
Differentiated mouse BC3H1 myogenic cells secrete substrate-associated macromolecules (SAM) which restrict the proliferation of undifferentiated cells and promote both cell shape changes and expression of predominantly the vascular smooth muscle (VSM)-specific isoform of the contractile protein α-actin. While we previously reported that high cell density was required for stimulating maximal expression of VSM α-actin in BC3H1 cells (Strauch and Reeser: Journal of Biological Chemistry264:8345-8355, 1989), the permissive effect of SAM on myoblast cytodifferentiation was not at all dependent on the formation of cell to cell contacts. This observation suggests that biogenesis of an extracellular matrix rather than the formation of physical contacts between cells may be the rate-limiting step for induction of VSM α-actin expression at high cell density. The biologically active moieties in SAM that promote cytodifferentiation also are expressed by mouse embryonic fibroblast cell lines and are distinctly different from a class of adheron-like macromolecules released by differentiated BC3H1 myocytes directly into the culture medium. While SAM was cell growth restrictive, reconstituted particulate material (RPM) prepared from myocyte-conditioned medium promoted the adhesion and proliferation of growth-arrested myoblasts. SAM and RPM are composed of different polypeptide subunits which collectively may establish microenvironmental conditions that are permissive for BC3H1 myogenic cell differentiation.
Additional Material:
8 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jcp.1041460302
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