Effects of IGF-I on the synthesis and processing of glycosaminoglycan in cultured chick chondrocytes.
We have studied the effect of the somatomedin IGF-I on stimulation of synthesis of DNA, RNA, protein, and glycosaminoglycan in chick chondrocytes. Stimulation of RNA and protein synthesis was rapid, occurring within 10 min after addition of IGF-I. Stimulation of sulphation required a lag time of about 2 h, whether chains were initiated on native protein core or on the artificial acceptor 4-methyl-umbelliferyl-beta-D-xyloside. DNA synthesis was not stimulated until after 10 h of exposure to IGF-I. Investigation of the rate of processing of proteoglycan core protein after pulse-labelling chondrocytes with 35SO4 yielded data which were best described by a biexponential function. IGF-I had no effect on the t 1/2 of the initial phase (16.44 min in the absence of IGF-I and 20.38 min in the presence of IGF-I). However, addition of IGF-I resulted in a decrease in the t 1/2 of the terminal phase from 122.58 to 55.44 min, which may reflect an increase in synthesis in the enzymes necessary for polymerization and sulphation of proteoglycan.
Kemp
S F
SF
Arkansas Children's Hospital, Little Rock.
Kearns
G L
GL
Smith
W G
WG
Elders
M J
MJ
D053674:Aggrecans; D000818:Animals; D002356:Cartilage / Q000378:metabolism*; D002478:Cells, Cultured; D002642:Chick Embryo; D004247:DNA / Q000096:biosynthesis; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins / Q000378:metabolism; D006025:Glycosaminoglycans / Q000096:biosynthesis*; D006027:Glycosides / Q000008:administration & dosage; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D037181:Lectins, C-Type; D014176:Protein Biosynthesis; D011509:Proteoglycans; D012313:RNA / Q000096:biosynthesis; D013002:Somatomedins / Q000494:pharmacology*
D053674:Aggrecans; D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D006025:Glycosaminoglycans; D006027:Glycosides; D037181:Lectins, C-Type; D011509:Proteoglycans; D013002:Somatomedins; C010807:xylosides; D012313:RNA; D007334:Insulin-Like Growth Factor I; D004247:DNA