Erythropoietin (EPO) signaling plays a vital role in erythropoiesis by regulating proliferation and lineage-specific differentiation of hematopoietic progenitor cells. An important downstream response of EPO signaling is calcium influx, which is regulated by transient receptor potential channel (TRPC) proteins, particularly TRPC2 and TRPC6. While EPO induces Ca2+influx through TRPC2, TRPC6 inhibits the function of TRPC2. Thus, interactions between TRPC2 and TRPC6 regulate the rate of Ca2+influx in EPO-induced erythropoiesis. In this study, we observed that the expression of TRPC6 in c-KIT positive erythroid progenitor cells is regulated by DOT1L. DOT1L is a methyltransferase that plays an important role in many biological processes during embryonic development, including early erythropoiesis. We previously reported that Dot1L knockout (Dot1L-KO) hematopoietic progenitors in the yolk sac failed to develop properly, which resulted in lethal anemia. In this study, we have detected a marked downregulation of Trpc6 gene expression in Dot1L-KO progenitor cells in the yolk sac compared to wildtype. However, the expression of Trpc2, the positive regulator of Ca2+influx, remained unchanged. The promoter and the proximal region of the Trpc6 gene loci exhibited an enrichment of H3K79 methylation, which is mediated solely by DOT1L. As the loss of DOT1L affects the expression of TRPC6, which inhibits Ca2+influx by TRPC2, Dot1L-KO progenitor cells in the yolk sac exhibit accelerated and sustained high levels of Ca2+influx. Such heightened Ca2+ levels might have detrimental effects on the development of hematopoietic progenitor cells in response to erythropoietin.

中文翻译：

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DOT1L甲基转移酶调节红细胞祖细胞对红细胞生成素的钙内流

促红细胞生成素（EPO）信号通过调节造血祖细胞的增殖和谱系特异性分化在促红细胞生成中起着至关重要的作用。EPO信号的重要下游响应是钙内流，其受瞬时受体电位通道（TRPC）蛋白（尤其是TRPC2和TRPC6）调节。EPO通过TRPC2诱导Ca2 +流入，而TRPC6抑制TRPC2的功能。因此，TRPC2和TRPC6之间的相互作用调节EPO诱导的红细胞生成过程中Ca2 +流入的速率。在这项研究中，我们观察到DOT1L调节c-KIT阳性红系祖细胞中TRPC6的表达。DOT1L是一种甲基转移酶，在胚胎发育过程中的许多生物学过程中（包括早期红细胞生成）起着重要作用。我们先前曾报道卵黄囊中的Dot1L基因敲除（Dot1L-KO）造血祖细胞未能正常发育，从而导致致命性贫血。在这项研究中，我们发现与野生型相比，卵黄囊Dot1L-KO祖细胞中Trpc6基因表达明显下调。但是，Trpc2（Ca2 +流入的正调节剂）的表达保持不变。Trpc6基因位点的启动子和近端区域表现出H3K79甲基化的富集，该富集仅由DOT1L介导。由于DOT1L的丢失会影响TRPC6的表达，从而抑制TRPC2的Ca2 +内流，因此卵黄囊中的Dot1L-KO祖细胞表现出加速和持续的高水平Ca2 +内流。