Exogenous sphingomyelinase increases collagen and sulphated glycosaminoglycan production by primary articular chondrocytes: an in vitro study

摘要: We previously established a role for the second messenger ceramide in protein kinase R (PKR)-mediated articular cartilage degradation. Ceramide is known to play dual collagen gene regulation, with effect of on promoter activity being dependent its concentration. Treatment cells low doses sphingomyelinase produces small increases endogenous ceramide. investigated whether influences chondrocyte matrix homeostasis and, if so, PKR this process. Bovine chondrocytes were stimulated 7 days increase levels To inhibit PKR, 2-aminopurine was added duplicate cultures. De novo sulphated glycosaminoglycan and synthesis measured by adding [35S]-sulphate [3H]-proline media, respectively. Chondrocyte phenotype using RT-PCR Western blot analysis. Over days, increased release newly synthesized into whereas inhibition sphingomyelinase-treated reduced level collagen. Sphingomyelinase treated expressed col2a1 mRNA, which indicative normal phenotype; however, significant reduction type II detected. Therefore, increments appear push homeostatic balance toward extracellular but at expense chondrocytic phenotype, was, part, mediated PKR.