Transcription Factor HIF1 Negatively Regulates the Content of Glucose-6-Phosphate Dehydrogenase in HEK293T Cells

Abstract

The identification of new targets for the regulation of hypoxia-induced transcriptional factor HIF1 is an urgent problem in cellular and molecular biology. The cobalt chloride (CoCl2) inductor of HIF1 accumulation and topotecan blocker of its translation were used to test the phenomenon previously described in the rat brain of suppression of the key enzyme of the pentose phosphate pathway glucose-6-phosphate dehydrogenase (G6PDH) with transcription factor HIF1. Nontoxic doses of CoCl2 (50 and 100 μM) and topotecan (0.2 and 1 μM) were estimated on a primary culture of rat skin fibroblast. On human embryonic kidney HEK293T cells, the relationship between the accumulation of HIF1α and the content of G6PDH was investigated by Western blotting and dot-immunoenzyme assay. To test the relationship between dose-dependent CoCl2 and topotecan changes in HIF1α content and HIF1-dependent expression, HEK293T cells were transfected with the vector containing the luciferase gene under the control of an HIF1-dependent promoter (HRE). Its activity was verified by chemiluminescence. It was found that CoCl2 dose-dependently increased the content of HIF1α and increased luciferase activity, promoting a decrease in the amount of G6PDH. Topotecan, on the contrary, decreased the accumulation of HIF1α accompanied by a decrease in luciferase activity and normalization of the G6PDH content. The results confirm that the transcription factor HIF1 has a suppressive effect on the content of the primary enzyme of the pentose phosphate pathway in human cells.