Endoplasmic reticulum stress response in murine kidney exposed to acute hypobaric hypoxia.

Any perturbation in the normal functioning of endoplasmic reticulum (ER), such as due to hypoxia, triggers the unfolded protein response (UPR). We studied the temporal variation in gene expression in murine kidney exposed to acute hypobaric hypoxia. Molecular chaperones like Grp78, Grp94, Canx and Calr in the ER were transcriptionally downregulated. Further, the splicing of Xbp1 mRNA decreased, whereas transcription of the unspliced mRNA increased. This step produces Xbp1 protein, which is negatively regulated by the unspliced protein. Hence, the decreased splicing of Xbp1 along with decreased transcription of ER chaperones in kidney is a definite indication of reduced stress.