Effects and relationship of ERK1 and ERK2 in interleukin-1β-induced alterations in MMP3, MMP13, type II collagen and aggrecan expression in human chondrocytes

Abstract

Abstract. Interleukin (IL)-1β plays an important role in the pathogenesis of osteoarthritis and catabolic processes in articular cartilage. Growing evidence suggests that ERK1/2 activation is involved in IL-1β-mediated matrix metalloproteinase (MMP) 3, MMP13, type II collagen and aggrecan expression in chondrocytes. To investigate the respective effects and the relationship of ERK1 and ERK2, knockdown of ERK1 and/or ERK2 was performed in human chondrocytes using specific small interfering RNAs (siRNAs), and the cells were treated with IL-1β (10 ng/ml) for 24 h. Uninfected chondrocytes treated with IL-1β (10 ng/ml) were used as a positive control. Other cells cultured without IL-1β or siRNA treatment were used as a negative control. The mRNA levels of MMP3, MMP13, type II collagen and aggrecan were evaluated by quantitative real-time PcR. The protein levels of MMP3 and MMP13 in the culture medium were examined by ELISA. The protein levels of type II collagen, aggrecan, ERK1/2 and phospho-ERK1/2 were evaluated by western blotting. The results indicate that IL-1β enhances MMP3 and MMP13 expression and inhibits type II collagen and aggrecan expression. Activation of the MAPK/ERK pathway was observed. Knockdown of ERK1 or ERK2 significantly reversed these effects to similar degree. combined knockdown of ERK1 and ERK2 displayed synergistic effects. ERK1 and phospho-ERK1 or ERK2 and phospho-ERK2 were inhibited by knockdown of ERK1 or ERK2, respectively. No compensatory effect by up-regulation of the opposite isoform was observed. The combined knockdown suppressed ERK1/2 and phospho-ERK1/2. The data suggest that although inhibition of both ERK1 and ERK2 is more effective, inhibition of either ERK isoform may be sufficient and could be used for novel therapies or as drug targets for pharmacological intervention in cartilage breakdown in osteoarthritis.

Visfatin induces MUC8 and MUC5B expression via p38 MAPK/ROS/NF-κB in human airway epithelial cells

“…Within the signaling pathway, visfatin induces vascular endothelial growth factor, and production of matrix metalloproteinases via MAPK [8,16]. In addition, MUC8 or MUC5B expression is induced in response to a wide variety of stimuli, including nerve activation and inflammatory cytokines, such as IL-1β, IL-6, TNF-α, and prostaglandin E 2 through a process involving p38 or ERK1/2 MAPK activation [11,17,18].…”

“…ROS induce NF-κB activation by modifying the activity of one or more of the kinase enzymes in the NF-κB activation cascades [5]. Recent studies have reported that visfatin increases expression of inflammatory adhesion molecules through an ROS-dependent NF-κB signaling pathway in vascular endothelial cells [5,7,9,16,20]. Therefore, this study focused on correlation between visfatin-induced MUC8 and MUC5B expression and ROS formation via the NF-κB signaling pathway in human airway epithelial cells.…”

Signaling Pathways in Cartilage Repair

“…In vitro , IL-1 leads to the activation of ERK, p38 and JNK and is associated with the up-regulated expression of MMPs in chondrocytes and conversely, ERK1/2 inhibition decreases the release of MMP3 and MMP13 by human chondrocytes stimulated with IL-1β [228]. In addition, IL-1β exhibits inhibitory effects on collagen type II and aggrecan whose synthesis is necessary for cartilage repair.…”

“…In addition, IL-1β exhibits inhibitory effects on collagen type II and aggrecan whose synthesis is necessary for cartilage repair. Thus, IL-1β disrupts the balance between catabolic and anabolic activities, which may result in articular cartilage destruction [228], MMP13 is capable of cleaving type II collagen, whereas MMP3 is active against other components of the extracellular matrix, such as fibronectin and laminin.…”

“…The altered expression of MMP3, MMP13, type II collagen and aggrecan induced by IL-1β stimulation in human chondrocytes was significantly and similarly reverted by ERK1 or ERK2 knockdown; no isoform was significantly upregulated after the single knockdown of the other kinase, and the combined knockdown displayed synergistic effects [228]. …”