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Regulation of thrombospondin secretion by cells in culture
Author(s) -
Mumby Susanne M.,
AbbottBrown Debbie,
Raugi Gregory J.,
Bornstein Paul
Publication year - 1984
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041200304
Subject(s) - fibronectin , extracellular matrix , thrombospondin , secretion , cell culture , microbiology and biotechnology , thrombospondins , extracellular , glycoprotein , thrombospondin 1 , cell , biology , chemistry , biochemistry , angiogenesis , metalloproteinase , matrix metalloproteinase , genetics , cancer research
Thrombospondin (TS), a 450,000 molecular weight glycoprotein, is released from α‐granules of thrombin‐activated platelets and is secreted and incorporated into the extracellular matrix by several cell types in culture. We have examined the effects of cell density and transformation on the production of TS in cell culture. The levels of TS, per cell, in the culture medium of endothelial cells, smooth muscle cells, and fibroblasts were greater at lower cell densities; in fibroblasts the levels of two other extracellular matrix proteins, fibronectin and collagen, were unaffected by cell density. Our evidence indicates that the higher levels of TS in the culture medium, determined for lower‐density cells, were achieved by an increased secretion of the protein rather than by a reduction in degradation or incorporation into the extracellular matrix. TS production by normal and transformed Wl‐38 fibroblasts was the same, although the fibronectin level in the culture medium of the transformed cells was substantially decreased. These findings suggest that the production of TS by cells in culture is regulated in a different fashion from that of fibronectin or collagen.