Chemically mimicked hypoxia modulates gene expression and protein levels of the sodium calcium exchanger in HEK 293 cell line via HIF-1α

Up to now a little is known about the effect of hypoxia on the sodium calcium exchanger type 1 (NCX1) expression and function. Therefore, we studied how dimethyloxallyl glycine (DMOG), an activator and stabilizer of the hypoxia-inducible factor (HIF)-1 alpha, could affect expression of the NCX1 in HEK 293 cell line. We also tried to determine whether this activation can result in the induction of apoptosis in HEK 293 cells. We have found that DMOG treatment for 3 hours significantly increased gene expression and also protein levels of the NCX1. This increase was accompanied by a decrease in intracellular pH. Wash-out of DMOG did not result in reduction of the NCX1 mRNA and protein to original - control levels, although pH returned to physiological values. Using luciferase reporter assay we observed increase in the NCX1 promoter activity after DMOG treatment and using wild-type mouse embryonic fibroblast (MEF)-HIF-1(+/+) and HIF-1-deficient MEF-HIF-1(-/-) cells we have clearly shown that in the promoter region, HIF-1 alpha is involved in DMOG induced upregulation of the NCX1. Moreover, we also showed that an increase in the NCX1 mRNA due to the apoptosis induction is not regulated by HIF-1 alpha.