ERN1 (endoplasmic reticulum to nucleus signaling 1)-mediated signaling pathway plays an important role in glioma growth. We studied the possible role of protein kinases MAP4K3, MAP3K5, RIPK1, and RIPK2 as well as protein kinase interacting protein CIB1 in suppression of U87 glioma cell proliferation upon ERN1 knockdown. It was shown that blockade of ERN1 signaling enzyme function significantly decreases the expression level of genes encoding MAP4K3, RIPK2, and CIB1 in U87 glioma cells, but increases expression of RIPK1 gene. At the same time, the blockade of ERN1 signaling enzyme does not affect the expression of MAP3K5 gene in glioma cells. Hypoxia down-regulates the expression level of MAP3K5, MAP4K3, RIPK1, and RIPK2 mRNAs in control glioma cells. However, inhibition of ERN1 affected hypoxia-mediated changes in expression of these kinase genes and their magnitude. Results of this investigation clearly demonstrated that the expression of MAP4K3, RIPK1, RIPK2, and CIB1genes in U87 glioma cells in human U87 glioma cells relies on blockade of ERN1-mediated endoplasmic reticulum stress signaling and is mostly down-regulated by hypoxia in dependence of ERN1 enzyme function.
Key words: mRNA expression, ERN1 knockdown, MAP4K3, RIPK1, hypoxia, U87 glioma cells