Regulatory mechanism of transforming growth factor beta receptor type II degradation by interleukin-1 in primary chondrocytes

Interleukin-1 beta (IL-1 beta), a key-cytokine in osteoarthritis, impairs TGF beta signaling through T beta RII down-regulation by increasing its degradation. Here, we investigated the molecular mechanism that controls T beta RII fate in IL-1 beta treated cells. Chondrocytes were treated with IL-1 beta in the presence of different inhibitors. T beta RII and Cav-1 expression were assayed by Western blot and RT-PCR. We showed that IL-1 beta-induced degradation of T beta RII is dependent on proteasome and on its internalization in caveolae. In addition, IL-1 beta enhances Cav-1 expression, a major constituent of lipid raft. In conclusion, we enlighten a new mechanism by which IL-1 beta antagonizes TGF beta pathway and propose a model of T beta RII turnover regulation upon IL-1 beta treatment (C) 2012 Elsevier B.V. All rights reserved.