Decrease of Orai1 Ca2+ channel primes KLF1 transcription for terminal erythropoiesis

Abstract

Terminal erythropoiesis occurs through a complicated differentiation process that relies on erythropoietin (EPO) signal transduction and intracellular gene regulation. By studying the Orai1 Ca2+channel, we gain mechanistic insights into how EPO-mediated Ca2+signals modulate erythroid gene transcription following the maturation of RBCs. Here, we show that expression of Orai1 decreased in terminally differentiating HUDEP-2 and cord blood (CB)-derived CD71 primary erythroblasts, affecting the Ca2+homeostasis of erythroid cells. Repression of the Orai1 Ca2+channel using mutants promoted RBC differentiation efficiency in HUDEP-2 and iPSCs. In addition, Orai1 inactivation positively manipulated erythroid-specific genes by promoting Krupple-like factor 1 (KLF1) gene expression. We also found that EPO activates the Orai1 channel. Elimination of the EPO stimuli highly improved maturation efficiency, which might cause a decrease in Orai1 activity. Overall, this study demonstrated an unknown function of the Orai1 Ca2+channel in terminal erythropoiesis and improved the understanding of how EPO-mediated Ca2+signaling regulates erythroid gene transcription during RBC differentiation.