Transformation of eEF1Bδ into heat-shock response transcription factor by alternative splicing.

Protein translation factors have crucial roles in a variety of stress responses. Here, we show that eukaryotic elongation factor 1Bδ (eEF1Bδ) changes its structure and function from a translation factor into a heat-shock response transcription factor by alternative splicing. The long isoform of eEF1Bδ (eEF1BδL) is localized in the nucleus and induces heat-shock element (HSE)-containing genes in cooperation with heat-shock transcription factor 1 (HSF1). Moreover, the amino-terminal domain of eEF1BδL binds to NF-E2-related factor 2 (Nrf2) and induces stress response haem oxygenase 1 (HO1). Specific inhibition of eEF1BδL with small-interfering RNA completely inhibits Nrf2-dependent HO1 induction. In addition, eEF1BδL directly binds to HSE oligo DNA in vitro and associates with the HSE consensus in the HO1 promoter region in vivo. Thus, the transcriptional role of eEF1BδL could provide new insights into the molecular mechanism of stress responses.