HSF1-TPR Interaction Facilitates Export of Stress-induced

Stress conditions inhibit mRNA export, but mRNAs encoding heat shock proteins continue to be efficiently exported from the nucleus during stress. How HSP mRNAs bypass this stress-asso- ciated export inhibition was not known. Here, we show that HSF1, the transcription factor that binds HSP promoters after stress to induce their transcription, interacts with the nuclear pore- associating TPR protein in a stress-responsive manner. TPR is brought into proximity of the HSP70 promoter after stress and preferentially associates with mRNAs transcribed from this pro- moter. Disruption of the HSF1-TPR interaction inhibits the export of mRNAs expressed from the HSP70 promoter, both endogenous HSP70 mRNA and a luciferase reporter mRNA. These results suggest that HSP mRNA export escapes stress inhibition via HSF1-mediated recruitment of the nuclear pore- associating protein TPR to HSP genes, thereby functionally con- necting the first and last nuclear steps of the gene expression pathway, transcription and mRNA export.