Maturation-dependent thiol loss increases chondrocyte susceptibility to apoptosis.
The major aim of the current investigation was to evaluate the role of thiols during chondrocyte maturation and apoptosis. Using a thiol-sensitive fluorescent probe, we found that in chick growth plate chondrocytes, hypertrophy is accompanied by a decrease in the glutathione content. In this study, we show that the maturation-dependent loss of thiol, although not causing death of maturing chondrocytes, drastically increases susceptibility to apoptosis by oxidative and nitrosoactive stress. To investigate how the loss of thiol content in cultured chondrocytes affects the expression of the hypertrophic phenotype, we chemically manipulated intracellular thiol levels and analyzed the expression of important maturation markers. We found that thiol depletion causes a decrease in the expression of osteopontin, type X and type II collagen and a significant loss of alkaline phosphatase activity, suggesting that the expression of the hypertrophic phenotype is tightly regulated by redox levels in chondrocytes. Furthermore, severe thiol depletion profoundly affected cell survival under oxidative and nitrosoactive stress. It was concluded that the loss of thiol reserve is not only linked to the expression of the hypertrophic phenotype but also influenced chondrocyte survival, linking chondrocyte maturation and the activation of the apoptotic pathway.
Teixeira
Cristina C
CC
Department of Basic Science and Craniofacial Biology and Department of Orthodontics, New York University, College of Dentistry, New York, New York 10010, USA. ct40@nyu.edu
Rajpurohit
Ramesh
R
Mansfield
Kyle
K
Nemelivsky
Yelena V
YV
Shapiro
Irving M
IM
D000111:Acetylcysteine / Q000494:pharmacology; D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D002454:Cell Differentiation; D002470:Cell Survival; D002478:Cells, Cultured; D002642:Chick Embryo; D019902:Chondrocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D024043:Collagen Type II / Q000235:genetics; D024081:Collagen Type IX / Q000235:genetics; D003545:Cysteine / Q000378:metabolism; D005456:Fluorescent Dyes; D015870:Gene Expression; D005978:Glutathione / Q000378:metabolism; D006132:Growth Plate / Q000166:cytology / Q000378:metabolism; D009569:Nitric Oxide / Q000378:metabolism; D053495:Osteopontin; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D012795:Sialoglycoproteins / Q000235:genetics; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D014212:Tretinoin / Q000494:pharmacology
D024043:Collagen Type II; D024081:Collagen Type IX; D005456:Fluorescent Dyes; D012795:Sialoglycoproteins; D013438:Sulfhydryl Compounds; D053495:Osteopontin; D009569:Nitric Oxide; D019328:Buthionine Sulfoximine; D014212:Tretinoin; D000469:Alkaline Phosphatase; D005978:Glutathione; D003545:Cysteine; D000111:Acetylcysteine