Sphingomyelinase decreases type II collagen expression in bovine articular cartilage chondrocytes via the ERK signaling pathway

Abstract

Objective. Ceramide, a mediator of proinflammatory cytokine signaling, induces cartilage degradation and reduces type II collagen synthesis in articular cartilage. The accumulation of ceramide is associated with arthritis in Farber's disease. The aim of this study was to investigate the mechanism of ceramide-induced down-regulation of type II collagen.Methods. Bovine articular chondrocytes were stimulated with sphingomyelinase (SMase) to increase levels of endogenous ceramide. Components of the ERK pathway were inhibited by Raf-1 kinase inhibitor and the MEK inhibitor, PD98059. Cell extracts were analyzed by Western blotting for ERK-1/2, SOX9, c-Fos, and type II collagen, and the level of c-fos messenger RNA (mRNA) was analyzed by quantitative polymerase chain reaction. Localization of ERK-1/2, SOX9, and c-Fos was assessed by immunocytochemistry and confocal microscopy.Results. SMase treatment of chondrocytes caused sustained phosphorylation of ERK-1/2 throughout the cytoplasm and nucleus that was reduced by inhibitors of Raf-1 kinase and MEK-1/2. SMase treatment of chondrocytes also induced translocation of c-Fos to the nucleus and phospho-SOX9 to the cytoplasm and increased expression of c-fos mRNA. Type II collagen expression, which was down-regulated by SMase treatment, was restored by the MEK-1/2 inhibitor, PD98059.Conclusion. SMase down-regulates type II collagen in articular chondrocytes via activation of the ERK signaling cascade, redistribution of SOX9, and recruitment of c-Fos. This new mechanism for cartilage degradation provides potential targets for future treatment of arthritic disease.

Lipid Transport and Metabolism in Healthy and Osteoarthritic Cartilage

“…Ceramide might play a mediatory role in cartilage loss during OA due to increased chondrocyte apoptosis and by inducing proteoglycan degradation [89]. High levels of endogenous ceramide have been demonstrated to disrupt cartilage matrix homeostasis, resulting in down-regulation of type II collagen in articular cartilage [90,91]. In fact, acid ceramidase, by degrading ceramide, alters sphingolipid metabolism and improves chondrogenesis [92] (Figure 1).…”

Acid Ceramidase Maintains the Chondrogenic Phenotype of Expanded Primary Chondrocytes and Improves the Chondrogenic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells

“…For example, an early report [13] showed that a synthetic ceramide derivative (C2 ceramide) stimulated the expression of matrix metalloprotease (MMP) −1, 3 and 13 in rabbit articular chondrocytes, and induced chondrocyte apoptosis. Gilbert et al [14] also showed that treatment of bovine articular chondrocytes with sphingomyelinase, an enzyme that produces ceramide by sphingomyelin hydrolysis, decreased expression of collagen II. Elevated ceramide also has been documented in patients with rheumatoid and osteoarthritis [15], and inhibition of sphingosine-1-phosphate (S1P) production in induced rodent models of arthritis has led to beneficial clinical results [16].…”

Trabecular Bone Parameters, TIMP-2, MMP-8, MMP-13, VEGF Expression and Immunolocalization in Bone and Cartilage in Newborn Offspring Prenatally Exposed to Fumonisins

“…Disruption in glycosphingolipid synthesis enhances the development of osteoarthritis in mice [42]. Studies have also examined roles for ceramides in the regulation of type II collagen synthesis via the ERK (extracellular-signal-regulated kinase) signaling pathway [43], proteoglycans and glycosaminoglycans [44][45][46] and MMPs by chondrocytes [47].…”