Chromatin remodelling factor SMARCD2 (BAF60B) regulates transcriptional networks controlling early and late differentiation of neutrophil granulocytes

Differentiation of haematopoietic stem cells followsa hierarchical program of transcription-factor regulated events. Early myeloid cell differentiation is dependent on PU.1 and CEBPA (CCAAT/enhancer binding protein alpha), late myeloid differentiation is orchestrated by CEBPE (CCAAT/enhancer binding protein epsilon). The influence of SWI/SNF (SWItch/Sucrose Non-Fermentable) chromatin remodelling factors as novel master regulators of haematopoietic differentiation is only beginning to be explored. Here, we identified three homozygous loss-of-function mutations in SMARCD2 (SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily d, member 2), a member of the SWI/SNF complex, in three unrelated pedigrees. We find that SMARCD2-deficient hematopoiesis results in dysfunctional neutrophil granulocytes, characterized by specific granule deficiency, myelodysplasia, and an excess of blast cells. We can show that SMARCD2 controls early steps in the differentiation of myeloid-erythroid progenitor cells in mice and zebra fish. In vitro SMARCD2 interacts with the transcription factor CEBPE. Furthermore, we find that SMARCD2 controls expression of neutrophil proteins stored in specific granules and leads to transcriptional and chromatin changes in AML cells. Hence, we identify SMARCD2 as a key factor controlling myelopoiesis and as a potential tumour suppressor in leukemia.