Iron-Heme-Bach1 Axis Is Involved In Erythroblast Adaptation To Iron Deficiency

Iron plays the central role in the oxygen transport by the erythrocyte as a constituent of heme and hemoglobin. The importance of iron and heme also resides in their regulatory roles during erythroblast maturation. The transcription factor Bach1 may be involved in their regulatory roles since it is inactivated by direct binding of heme. To address whether Bach1 is involved in the responses of erythroblasts to iron status, low iron conditions that induced severe iron deficiency in mice were established. Under iron deficiency, extensive gene expression changes and mitophagy disorder were induced during maturation of erythroblasts. Bach1 mice showed more severe iron deficiency anemia in the developmental phase of mice and a retarded recovery once iron was replenished when compared with wild-type mice. In the absence of Bach1, the expression of globin genes and Hmox1 (encoding heme oxygenase-1) was de-repressed in erythroblasts under iron deficiency, suggesting that Bach1 represses these genes in erythroblasts under iron deficiency to balance the levels of heme and globin. Moreover, an increase in genome-wide DNA methylation was observed in erythroblasts of Bach1–/– mice under iron deficiency. These findings reveal the principle role of iron as a regulator of gene expression in erythroblast maturation and suggest that the iron-heme-Bach1 axis is important for a proper adaptation of erythroblast to iron deficiency to avoid toxic aggregates of non-heme globin. Overall design: Gene expression profiles were determined by microarry (GSE77694) and DNA methyomes were determined by WGBS.