Hsp90β interacts with MDM2 to suppress p53-dependent senescence during skeletal muscle regeneration

Cellular senescence plays both beneficial and detrimental roles in embryonic development and tissue regeneration, while the underlying mechanism remains elusive. Recent studies disclosed the emerging roles of heat-shock proteins in regulating muscle regeneration and homeostasis. Here, we found that Hsp90 beta, but not Hsp90 alpha isoform, was significantly upregulated during muscle regeneration. RNA-seq analysis disclosed a transcriptional elevation of p21 in Hsp90 beta-depleted myoblasts, which is due to the upregulation of p53. Moreover, knockdown of Hsp90 beta in myoblasts resulted in p53-dependent cellular senescence. In contrast to the notion that Hsp90 interacts with and protects mutant p53 in cancer, Hsp90 beta preferentially bound to wild-type p53 and modulated its degradation via a proteasome-dependent manner. Moreover, Hsp90 beta interacted with MDM2, the chief E3 ligase of p53, to regulate the stability of p53. In line with these in vitro studies, the expression level of p53-p21 axis was negatively correlated with Hsp90 beta in aged mice muscle. Consistently, administration of 17-AAG, a Hsp90 inhibitor under clinical trial, impaired muscle regeneration by enhancing injury-induced senescence in vivo. Taken together, our finding revealed a previously unappreciated role of Hsp90 beta in regulating p53 stability to suppress senescence both in vitro and in vivo.