Effect of hypoxia, glutamine and glucose deprivation on the expression of mRNA of the retinoblastoma binding proteins in glioma cells

D O Minchenko,S V Danylovsky,M Moenner,L L Karbovskyi,O H Minchenko

doi:10.30970/sbi.0501.136

Abstract

Hypoxia and ischemia, as well as endoplasmic reticulum stress, are principal factors which are necessary for tumor neovascularization and growth. We have studied the effect of blocking the endoplasmic reticulum – nuclei-1, the main signaling enzyme of stressing of the endoplasmic reticulum, on the expression of several retinoblastoma-related genes which play a significant role in the control of cell cycling, proliferation and apoptosis in glioma cell line U87. We have also studied the effect of hypoxia and ischemic conditions (glucose or glutamine deprivation) on the expression of these genes in control glioma cells and in subline of these cells with suppressed function of endoplasmic reticulum – nuclei-1 sensing and signaling enzyme. It was shown that blocking of endoplasmic reticulum – nuclei-1 signaling enzyme leads to increase in the expression levels of several retinoblastoma binding protein (RBBP) genes: RBBP2H1 (RDM5B), RBBP4 and RBBP8. Moreover, the expression levels of most of studied genes are significantly decreased under glucose or glutamine deprivation conditions both in control and endoplasmic reticulum – nuclei-1-deficient glioma cells. However, the expression levels of RBBP2H1 and RBBP2 (RDM5A) mRNA are increased in glutamine deprivation conditions in both tested cell types. The expression levels of RBBP4, RBBP7 and RBBP8 are decreased but such levels of RBBP2 and RBBP2H1 are increased in both tested cell types under the hypoxic conditions. Thus, the expression of most retinoblastoma-related genes is dependent on the endoplasmic reticulum – nuclei-1 signaling enzyme function in normal, hypoxic and ischaemic conditions. Keywords: mRNA expression, RBBP4, RBBP7, RBBP8, RBBP2, RBBP2H1, glioma cells, endoplasmic reticulum – nuclei-1, hypoxia, glucose and glutamine deprivation.

Highlights

Ischemia and hypoxia have been shown to induce a set of complex intracellular signaling events known as the unfolded protein response that is mediated by endoplasmic reticulum – nuclei-1 signaling enzyme, ISSN 1996-4536 Біологічні Студії / Studia Biologica 2011 Том 5/No1 С. 57–68D
We have shown that the exposure of glioma cells to hypoxic conditions leads to a significant decrease in the expression levels of retinoblastoma binding protein-4 (RBBP4), RBBP7 and RBBP8 mRNA both in control and endoplasmic reticulum – nuclei-1-deficient cells: -26%, -27% and -32%, correspondingly, in control glioma cells and -26%, -24% and -46%, correspondingly, in genetically modified cells
We have shown that complete blocking of the endoplasmic reticulum – nuclei-1 signal transduction pathway leads to an induction of the expression of several genes co ding for retinoblastoma binding and associate proteins (EID1, RDM5B, RBBP4 and DNA endonuclease) that bind directly to retinoblastoma proteins to regulate cell proliferation, apoptosis and tumor growth via retinoblastoma suppressor pathways [15, 22,23,24]

Summary

Introduction

As This enzyme participates in early cellular response to accumulation of misfolded proteins in the lumen of endoplasmic reticulum, occurring under both physiological and pathological conditions

Methods

Results

Discussion

Conclusion