bag3 gene expression is regulated by heat shock factor 1

BAG3 protein, a member of the BAG co-chaperones family, sustains cell survival, through its interaction with the heat shock protein (HSP) 70, in a variety of normal and neoplastic cell types. bag3 gene expression is induced by stressful stimuli. Here we report for the first time that two of the three putative heat shock-responsive elements (HSEs) in bag3 promoter interact with the heat shock factor (HSF) I in vitro and in vivo. Furthermore, downmodulation of HSF I protein levels by specific small interfering (si) RNAs results in reducing BAG3 protein levels, indicating that the transcription factor plays a major role in bag3 gene expression. Because of the anti-apoptotic role of BAG3 protein, these results disclose a previously unrecognized pathway, through which HSF I maintains cell survival.