UDP-sugar metabolism in Swarm rat chondrosarcoma chondrocytes.
UDP-sugars and adenine nucleotides were extracted from freshly isolated chondrocytes and primary cell cultures and analysed by anion-exchange h.p.l.c. The pool sizes of UDP-N-acetylglucosamine, UDP-N-acetylgalactosamine, UDP-glucose-galactose, UDP-glucuronate and UDP-xylose were 2.9, 1.2, 2.5, 0.6 and 0.03 nmol/10(6) freshly isolated chondrocytes. When chondrocytes were maintained in Dulbecco's modified Eagle medium supplemented with 15% foetal-bovine serum, synthesis of [35S]proteoglycan and [3H]protein decreased over the first 48 h in culture, as did the pools of UDP-glucuronate and ATP. In contrast, the size of the UDP-N-acetylhexosamine pools underwent little change during culture. [35S]Proteoglycan and [3H]protein syntheses were stimulated in cultures supplemented with serum or insulin compared with those maintained in medium alone, in agreement with previous results. However, the UDP-sugar pool sizes were the same in both supplemented and non-supplemented cultures. In cultures maintained in the presence of [1-3H]glucose, the UDP-sugars were labelled to a constant 3H specific radioactivity which was very similar to that of the labelling medium. UDP-N-acetylhexosamines were labelled to constant 3H specific radioactivity with [6-3H]glucosamine as a precursor, but only about 1 in 375 of these UDP-sugars was derived from the amino sugar in the presence of glucose. The half-life (t1/2) for UDP-hexoses, UDP-glucuronate and UDP-N-acetylhexosamines was about 12, 12 and 50 min respectively.
Sweeney
C
C
Department of Biochemistry, Charing Cross and Westminster Medical School, London, U.K.
Mackintosh
D
D
Mason
R M
RM
D000818:Animals; D001769:Blood; D002356:Cartilage / Q000166:cytology / Q000378:metabolism*; D002478:Cells, Cultured; D002813:Chondrosarcoma; D005944:Glucosamine / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D006025:Glycosaminoglycans / Q000096:biosynthesis; D007328:Insulin / Q000494:pharmacology; D010766:Phosphorylation; D011509:Proteoglycans / Q000096:biosynthesis; D051381:Rats; D014407:Tumor Cells, Cultured; D014539:Uridine Diphosphate Sugars / Q000378:metabolism*
D006025:Glycosaminoglycans; D007328:Insulin; D011509:Proteoglycans; D014539:Uridine Diphosphate Sugars; D005947:Glucose; D005944:Glucosamine