During development, ATP-dependent chromatin-remodelling complexes control certain temporal and spatial changes in gene expression that drive differentiation. Mammalian SWI-SNF-like chromatin-remodelling complexes contain one of two ATPase subunits: brahma (BRM) or brahma-related gene 1(BRG1). Now, Griffin and colleagues report that BRG1-containing SWI-SNF-like complexes are required for primitive erythropoiesis and early vascular development in mice (see ). The researchers show that when Brg1 is conditionally deleted in developing haematopoietic and endothelial cells, mouse embryos die at midgestation from anaemia. The primitive erythrocytes in these embryos fail to transcribe embryonic α- and β-globins, they report, and subsequently undergo apoptosis. Vascular remodelling in the extra-embryonic yolk sac of Brg1 mutant embryos is also abnormal, but the additional loss of Brm does not exacerbate their erythropoietic or vascular abnormalities. These results extend previous experiments in which hypomorphic Brg1 mutations prevented the transcription of adult but not of embryonic β-globin genes, note the researchers, and reveal non-redundant roles for BRM and BRG1 during primitive erythropoiesis and early vascular development.
