Ubiquitination of heat shock protein 27 is mediated by its interaction with Smad ubiquitination regulatory factor 2 in A549 cells

Smad ubiquitination regulatory factor 2 (Smurf2) is a crucial part of the ubiquitin-proteasome pathway (UPP) that regulates cellular signal transduction via ubiquitin-dependent degradation of some substrates and receptors. The biological function of Smurf2 in lung diseases, however, is not clear. In this study, the authors found that overexpression of Smurf2 altered the subcellular localization and distribution of heat shock protein 27 (HSP27), and induced a decrease of HSP27 protein levels through HSP27 degradation by the UPP in human lung adenocarcinoma epithelial cell line A549. Colocalized assay using confocal microscopy and coimmunoprecipitated reciprocally by either antibody indicated the interaction between Smurf2 and HSP27, which suggested that Smurf2 mediated ubiquitylation-dependent degradation of HSP27 through their interaction in A549 cells.