Post-receptor actions of somatomedin on chondrocyte collagen biosynthesis.
The anabolic effects of human somatomedin C on freshly isolated Swarm chondrosarcoma chondrocytes were studied. Physiological concentrations (2-34 nM) of somatomedin, but not growth hormone, stimulated the incorporation of radiolabeled precursors into collagen and non-collagen proteins, RNA and proteoglycans. The 120% increase in radiolabeling of collagen with [3H]proline by 10 nM somatomedin C was not due to changes in the rate of [3H]proline uptake. Similarly, the specific activity of newly synthesized [3H]proline-labeled collagen was not increased by 10 nM somatomedin C, indicating that changes in proline pool size or compartmentalization of [3H]proline were not involved. Somatomedin C had no effect on the rate of [3H]collagen degradation. The ability of somatomedin C to stimulate collagen synthesis was unaffected by concentrations of actinomycin D which inhibited chondrocyte RNA synthesis 90% or more. These results demonstrate that somatomedin exerts a general anabolic effect on chondrosarcoma chondrocyte metabolism. The fact that somatomedin C stimulates chondrocyte collagen synthesis in the absence of RNA synthesis suggests that this effect may be at the post-transcriptional level.
D000818:Animals; D002356:Cartilage / Q000378:metabolism*; D002813:Chondrosarcoma / Q000378:metabolism; D003094:Collagen / Q000096:biosynthesis*; D005786:Gene Expression Regulation / Q000187:drug effects; D013006:Growth Hormone / Q000494:pharmacology; D011509:Proteoglycans / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000502:physiology*; D014158:Transcription, Genetic / Q000187:drug effects
D011509:Proteoglycans; D013002:Somatomedins; D013006:Growth Hormone; D003094:Collagen