Decrease of ECC1 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. Although recent studies have shown that Ca2+-mediated intracellular signaling may contribute to the proper maturation of erythroid cells, the underlying regulation of the Ca2+ channel remains poorly understood. By studying the Erythroid Ca2+ channel 1 (ECC1), we gained mechanistic insights into how EPO-mediated Ca2+ signals modulate erythroid gene transcription following the maturation of RBCs. Here, we show that expression of ECC1 decreased in terminally differentiating HUDEP-2 and cord blood (CB)-derived CD71 primary erythroblasts, affecting the Ca2+ homeostasis of erythroid cells. Repression of the ECC1 Ca2+ channel using mutants and knock-out of ECC1 promoted RBC differentiation efficiency in HUDEP-2 and iPSCs. In addition, ECC1 inactivation positively manipulated erythroid-specific genes by promoting Krüppel-like factor 1 (KLF1) gene expression. We also found that EPO activates the ECC1 Ca2+ channel, especially in pro- and basophilic-erythroblasts stages. Elimination of the EPO stimuli highly improved maturation efficiency, which might cause a decrease in ECC1 channel activity..Overall, this study demonstrated an unknown function of the ECC1 Ca2+ channel in terminal erythropoiesis and improved the understanding of how EPO-mediated Ca2+ signaling regulates erythroid gene transcription during red blood cell differentiation.