Additional evidence for this coordination between tissue-specific BAF complexes and transcription factors comes from studies of heart development. Baf45c-containing complexes are required for heart and muscle development in zebrafish (Danio rerio)39. In addition, BAF60C is selectively expressed in the regions of the mouse embryo that give rise to a heart and is required for morphogenesis of the heart, differentiation into cardiac and skeletal muscle cells40 and establishment of left–right asymmetry in the early embryo41. Remarkably, ectopic expression of BAF60C but not BAF60A, in coordination with the transcription factors GATA4 and TBX5, is sufficient to induce the development of beating cardiomyocytes from non-cardiogenic mesoderm in the developing embryo42 (Figs 1a and 2). Hence, BAF complexes are required for cardiac fate determination. But the closely related polybromo-containing BAF (PBAF) complexes (a subfamily of mouse SWI/SNF complexes defined by the incorporation of polybromo (also known as BAF180)) are expressed in the epicardium and have roles that are non-redundant with those of BAF60C in mediating coronary development and cardiac chamber maturation43,44. By contrast, PBAF complexes are not required for ESC formation or function: deletion
