[Bach transcription factors regulate hematopoietic stem/progenitor cell differentiation in response to environmental changes].

Differentiation of hematopoietic stem/progenitor cells should be tightly regulated depending on the environmental changes to maintain homeostasis. For example, erythropoiesis repression and myelopoiesis induction are widely recognized as infectious/inflammatory conditions. Transcription factors are expected to play significant roles in achieving such alterations. However, the precise mechanism by which the differentiation trajectory shift is controlled under environmental changes has not fully been elucidated. In this study, we showed that Bach transcription factors organize the erythro-myeloid differentiation in hematopoietic stem/progenitor cells in response to the environmental changes. Under the steady state, Bach transcription factors support erythroid differentiation and repress myeloid differentiation by regulating the expression of their target genes. In contrast, the functions of Bach transcription factors were repressed, which induced myelopoiesis and repressed erythropoiesis, under emergency conditions, such as infection/inflammation. Competitive roles of Bach transcription factors and C/EBP, the key regulator of myelopoiesis, might be important for tuning erythro-myeloid differentiation trajectory and its shift in response to infection/inflammation. Disfunction of Bach transcription factors was considered to be related to anemia in chronic inflammation and myelodysplastic syndromes. In addition, considering previous findings, Bach2 might possess important roles in the conditioning of the hematopoietic system for subsequent emergency conditions.