Heat shock transcription factor HSF1 regulates the expression of the Huntingtin-interacting protein HYPK.

BACKGROUND: The Huntingtin-interacting protein HYPK possesses chaperone-like activity. We hypothesized that the expression of HYPK could be regulated by heat shock factor HSF1, a transcriptional regulator of chaperone genes. METHODS: HYPK expression in HeLa cells was assessed by RT-PCR and Western blot analysis. In vivo binding of HSF1 to the HYPK promoter was analyzed by chromatin immunoprecipitation assays. The requirement for HYPK in heat-shocked cells was examined using HYPK-knockdown cells. RESULTS: Levels of HYPK mRNA were slightly increased by heat treatment; however, the levels decreased in HSF1-silenced cells. The HYPK promoter was bound by HSF1 in a heat-inducible manner; however, its core promoter activity was notably suppressed upon heat shock. When cells were exposed to heat shock, silencing HYPK caused a decrease in cell viability. CONCLUSIONS: HYPK is a novel target gene of HSF1. HSF1 maintains HYPK expression in heat-shocked cells. GENERAL SIGNIFICANCE: The maintenance of HYPK expression by HSF1 is necessary for the survival of cells under thermal stress conditions.