Project description:Loss of subcellular lipid transport due to ARV1 deficiency disrupts organelle homeostasis and activates the unfolded protein response
Project description:The accumulation of unfolded proteins in the lumen of the endoplasmic reticulum (ER) causes stress and induces the unfolded protein response (UPR) which is characterised in part by the transcriptional induction of genes involved in assisting protein folding. Translational responses to ER stress have been less well described and here we report on a genome-wide analysis of translational regulation in the response to the ER stress-inducing agent dithiothreitol (DTT) in Saccharomyces cerevisiae. Although the observed polysome profiles were similar under control and ER stress conditions microarray analysis identified transcipt-specific translational regulation. Genes with functions in ribosomal biogenesis and assembly were translationally repressed under ER stress. In contrast mRNAs for known UPR genes, including the UPR transcription factor HAC1, the ER-oxidoreductase ERO1 and the ER-associated protein degradation (ERAD) gene DER1 were enriched in polysomal fractions under ER stress conditions. In addition, we show that splicing of HAC1 mRNA is required for efficient ribosomal loading and that Gcn2p is required for normal HAC1 splicing, so shedding light on the role of this protein kinase in the UPR pathway. Keywords: stress response, translational analysis
Project description:Ire1 is an endoplasmic reticulum (ER)-located transmembrane protein that triggers the unfolded protein response. I recently noticed that Ire1 is activated not only in response to ER accumulation of unfolded proteins but also alongside diauxic shift in yeast Saccharomyces cerevisiae cells. I thus asked how different the Ire1-target genes upon two distinct scenes, a canonical ER -stressing stimuli and diauxic shift. Thus NGS transcriptome analysis was performed by using IRE1+ and ire1-delta mutant yeast cells under these conditions.
Project description:In the yeast Saccharomyces cerevisiae, accumulation of misfolded proteins in the endoplasmic reticulum (ER) causes ER stress and activates the unfolded protein response (UPR) mediated by Hac1p, whereas the heat shock response (HSR) mediated by Hsf1p mainly regulates cytosolic processes and protects the cell from different stresses. In this study, we find that a constitutive activation of the HSR by over-expression of a mutant HSF1 gene could relieve ER stress in both wild type and hac1∆ UPR-deficient cells. We studied the genome-wide transcriptional response in order to identify regulatory mechanisms that govern the interplay between UPR and HSR responses. Interestingly, we find that the regulation of ER stress via HSR is mainly through facilitation of protein folding and secretion and not via the induction of Rpn4-dependent proteasomal activity.
