Hypoxia differently modulates gene expression of inositol 1,4,5-trisphosphate receptors in mouse kidney and HEK 293 cell line.

Hypoxia is a state of insufficient oxygen supply of the tissue or cell. Kidney tissue is highly sensitive to oxygen deprivation and easily develops renal ischemic injury. Calcium transporters very sensitively react to oxygen deficiency. We investigated whether hypoxia affects the gene expression of intracellular calcium transporters in the intact kidney, and we compared the response to that of HEK 293 cells. Our results showed that, while in mouse kidney tissue hypoxia elevates mRNA for inositol 1,4,5-trisphosphate receptors (IP3R) type 1 (IP3R1) and ryanodine receptors (RyR) type 2 (RyR2), in culture of HEK 293 cells the gene expression of all IP3Rs decreased without affecting viability of the cells. RyR2 mRNA in HEK 293 cells was not significantly changed, but RyR1 gene expression was significantly increased by hypoxia. The different response of kidney tissue and HEK 293 cells to hypoxia could be due to unequal differentiation state of the cells in intact tissue and cultured embryonic cell line. The physiological relevance of this observation remains to be determined.