Enhanced sulfated-proteoglycan core protein synthesis by incubation of rabbit chondrocytes with recombinant transforming growth factor-beta 1.
Rabbit articular chondrocytes were incubated with recombinant transforming-growth-factor-beta 1 (rhTGF-beta 1) and its effect on newly synthesized proteoglycan measured. rhTGF-beta 1 stimulated proteoglycan synthesis at a concentration as low as 5 ng/ml without further increases in radiosulfate incorporation up to 50 ng/ml. The quantitative increase in radiosulfate incorporation in rh-TGF-beta 1-treated chondrocytes was greater in the cell-associated culture compartment than in the medium compartment. rhTGF-beta 1 promoted an increased proteoglycan retention in the cell-associated compartment as evidenced by an increase in the t1/2 of retention from 8 h to 11 h. Specific enhanced synthesis of [35S]-methionine-labeled core proteins was seen in rh-TGF-beta 1-treated chondrocytes. rh-TGF-beta 1 increased the synthesis of the 2 core proteins derived from hydrodynamically large proteoglycans. They possessed apparent molecular weights of greater than 480 kD and 390 kD after 3-5% acrylamide gel electrophoresis. A compartmental analysis revealed that the cell-associated culture compartment contained only the larger of the 2 core proteins derived from large proteoglycans. Two other core proteins with apparent molecular weights 52 kD and 46 kD were also stimulated by rhTGF-beta 1. These results indicated that TGF-beta probably plays a significant role in stimulating proteoglycan core protein synthesis in articular chondrocytes and therefore may be an important growth factor in the restoration of cartilage extracellular matrix after injury.
Malemud
C J
CJ
Department of Medicine, Case Western Reserve University, Cleveland, Ohio 44106.
Killeen
W
W
Hering
T M
TM
Purchio
A F
AF
D053674:Aggrecans; D000818:Animals; D002358:Cartilage, Articular / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D006025:Glycosaminoglycans / Q000096:biosynthesis; D008970:Molecular Weight; D011509:Proteoglycans / Q000096:biosynthesis* / Q000737:chemistry; D011817:Rabbits; D011994:Recombinant Proteins / Q000494:pharmacology; D013431:Sulfates / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D053674:Aggrecans; D006025:Glycosaminoglycans; D011509:Proteoglycans; D011994:Recombinant Proteins; D013431:Sulfates; D016212:Transforming Growth Factor beta