IRE1 knockdown modifies hypoxic regulation of cathepsins and LONP1 genes expression in U87 glioma cells

Abstract

We have studied the effect of hypoxia on the expression of genes encoding for LONP1/PRSS15 and cathepsins in U87 glioma cells in relation to inhibition of inositol requiring enzyme-1 (IRE1). It was shown that hypoxia up-regulated the expression of CTSA, CTSB, CTSD, CTSF, CTSK, and LONP1 genes and down-regulated the expression of CTSC, CTSL, CTSO, and CTSS genes in control glioma cells (transfected by empty vector). Inhibition of ІRE1 signaling enzyme function in these glioma cells modified effect of hypoxia on the expression of most studied genes: eliminated the effect of hypoxia on CTSA, and LONP1 genes, introduced reverse changes on CTSD and CTSS genes, reduced – on CTSF and CTSK genes, and enhanced – on CTSB and CTSL genes. Therefore, hypoxia affected the expression level of most studied genes in relation to the functional activity of IRE1 enzyme, a central mediator of endoplasmic reticulum stress, which control cell proliferation and tumor growth.