Erythroid‐extrinsic regulation of normal erythropoiesis by retinoic acid receptors

Summary Vitamin A and its derivatives (retinoids) are important regulators of haematopoiesis, acting via retinoic acid receptors ( RAR s). Epidemiological studies indicated an association of vitamin A deficiency with anaemia in humans. To define the requirements of RAR s in erythropoiesis, we evaluated erythroid parameters in RAR germ‐line deficient and conditional knock out mice with erythroid specific deletion of RAR s. Adult RAR γ −/ − mice were anaemic, however, Epor‐ Cre Rara fl/fl , Epor ‐Cre Rarg fl/fl and Epor ‐Cre Rara fl/fl g fl/fl mice were normal, indicating a lack of an erythroid intrinsic RAR function. Therefore, erythroid‐specific RAR function is dispensable for erythropoiesis and RAR γ plays an erythroid extrinsic role in erythropoiesis.