Cartilage sulfation inhibitor from rat liver: partial characterization of properties and biologic action.
Cartilage sulfation (somatomedin) inhibitors (CSI) from rat liver produce reversible inhibition of cartilage growth. After gel filtration Sephadex G-200, CSI appear to have MW approximately 100,000 and they are urea- and trypsin-labile factors. To explore further the mechanism of CSI action, we used the chick pelvic rudiment bioassay and studied the effect of CSI on the incorporation on 35S-sulfate (proteoglycan synthesis), 14C-leucine (protein synthesis), 3H-uridine (RNA synthesis), and 3H-thymidine (DNA synthesis). Normal rat serum (NRS) significantly stimulated the incorporation of all four isotopes, as expected. After a 24-hour incubation, CSI significantly blunted cartilage stimulation by NRS regarding total isotope uptake (1), 35S-sulfate (NRS, 96 +/- 8 mcg/100 mg cartilage dry weight; NRS + CSI, 48 +/- 4, mean +/- SEM, n = 29, P less than .05); and (2) 14C-leucine (NRS, 2,089 +/- 172 cpm/mg dry weight; NRS + CSI, 1,102 +/- 141, n = 18, P less than .05); and (3) 3H-uridine (NRS, 6,711 +/- 832 cpm/mg; NRS + CSI, 3,227 +/- 425 cpm/mg, n = 18, P less than .05); but not (4) 3H-thymidine (NRS, 3,540 +/- 620 cpm/mg; NRS + CSI 3,249 +/- 285, n = 19). The inhibition of 35S-sulfate and 14C-leucine uptake by CSI was dose-dependent and reversible. For 35S-sulfate, uptake by cartilage incubated with CSI alone for 40 hours was 13 +/- 3 micrograms/100 mg; with CSI for 16 hours then fresh medium with NRS for 24 hours uptake was 39 +/- 12, P less than .05.(ABSTRACT TRUNCATED AT 250 WORDS)
D000818:Animals; D001681:Biological Assay; D002356:Cartilage / Q000378:metabolism*; D002642:Chick Embryo; D004247:DNA / Q000096:biosynthesis; D006131:Growth Inhibitors; D008099:Liver / Q000032:analysis*; D009924:Organ Culture Techniques; D009930:Organic Chemicals; D014176:Protein Biosynthesis; D011509:Proteoglycans / Q000096:biosynthesis; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000032:analysis / Q000037:antagonists & inhibitors* / Q000502:physiology; D013431:Sulfates / Q000378:metabolism
D006131:Growth Inhibitors; D009930:Organic Chemicals; D011509:Proteoglycans; D013002:Somatomedins; D013431:Sulfates; C040080:cartilage sulfation inhibitors; D012313:RNA; D004247:DNA