Cell division and collagen synthesis in cultured fibroblasts

Abstract

Summary The rate of synthesis of collagen and of non-collagen proteins at high and at low cell density was determined in the established mouse embryo fibroblast line 3T6 and in several human fibroblast lines. Collagen synthesis is always more rapid in proliferating than in stationary cultures. In 3T6 and in “old” but not in “young” human fibroblast lines the percentage of collagen to total protein synthesized is higher in stationary than in proliferating cultures, not because collagen synthesis is stimulated at high cell density but because synthesis of other proteins is more repressed than collagen synthesis. Arresting cell proliferation by exposure of the cultures to thymidine does not change the rate of collagen synthesis relative to the synthesis of other proteins. Omission of serum from the culture medium strongly diminishes cell proliferation, DNA and protein synthesis. In growing 3T6 and “old” human fibroblast lines, omission of serum inhibits non-collagen protein synthesis more strongly than collagen synthesis, so that a higher percentage of the protein synthesized is collagen. No such effect is found in “young” human fibroblast lines.