Data are expressed compared to control 0 h

Data are expressed compared to control 0 h. Individual SWI/SNF components have been involved in muscle differentiation. Here, we show that this grasp myogenic differentiation factor MyoD interacts with more than one SWI/SNF subunit, including the catalytic subunit BRG1, BAF53a and the tumor suppressor BAF47/INI1. Downregulation of each of these SWI/SNF subunits inhibits skeletal muscle terminal differentiation but, interestingly, at different differentiation actions and extents. BAF53a downregulation inhibits myotube formation but not the expression of early muscle-specific genes. BRG1 or BAF47 downregulation disrupt both proliferation and differentiation genetic programs expression. Interestingly, BRG1 and BAF47 are part of the SWI/SNF remodeling complex as well as the N-CoR-1 repressor complex in proliferating myoblasts. However, our data show that, upon myogenic differentiation, BAF47 shifts in favor of N-CoR-1 complex. Finally, BRG1 and BAF47 are well-known tumor suppressors but, strikingly, only BAF47 seems essential in the myoblasts irreversible cell cycle exit. Together, our data unravel differential roles for SWI/SNF subunits in muscle differentiation, Cerubidine (Daunorubicin HCl, Rubidomycin HCl) with BAF47 playing a dual role both in the permanent cell cycle exit and in the regulation of muscle-specific genes. Introduction The SWI/SNF complex (SWI, mating type switch; SNF, sucrose non-fermenting) is an evolutionarily well-conserved ATPase-powered chromatin-remodeling complex. This complex, composed of a dozen of proteins, is usually implicated in the sliding or removing of nucleosomes, influencing gene expression regulation, DNA repair and replication (for review [1], [2]). In mammals, SWI/SNF contains one of two related ATPases: Brahma (BRM, encoded by SMARCA2) or Brahma-Related Gene 1 (BRG1, encoded by SMARCA4). In addition, the complex contains BAFs (BRM or BRG1-Associated Factors). The core subunits Rabbit polyclonal to PNPLA2 that are required to reconstitute the SWI/SNF remodeling function in vitro areBAF47/INI1/SNF5/SMARCB1, BAF155/SMARCC1 and BAF170/SMARCC2). Combinatorial assembly of six to eight additional BAFs confers specificity of function to individual SWI/SNF complexes (for review [1], [3]). Some SWI/SNF subunits can participate to other multiprotein complexes also involved in gene transcription regulation, such as N-CoR, WINAC, NUMAC and mSIN3A [2], [4]. SWI/SNF remodeling activity is involved in many physiological processes such as embryonic development, maintenance of pluripotency, cell reprogramming [5], cellular differentiation and pathological processes like tumorigenesis or neurological disorders [6], [7]. Indeed, several SWI/SNF subunits, such as BRG1, BAF250, BAF180 and BAF47, are mutated Cerubidine (Daunorubicin HCl, Rubidomycin HCl) in various cancer types and some are bona fide tumor suppressors, such as BAF47 [3], [6], [7]. Far from functioning in a similar way in all cell types, SWI/SNF complexes and subunits have a range of specific and context-dependent roles in cell differentiation and proliferation [8]. Indeed, individual SWI/SNF subunits deregulation does not induce the same phenotypes. BRG1 is required for neuronal differentiation [9], [10], cardiogenesis [11], muscle differentiation (32, 33) and a dominant-negative BRG1 allele blocks myeloid differentiation [12], whereas loss of BRG1 in keratinocytes results in limb patterning defects [13]. BAF47/INI1 plays a crucial role in orchestrating the balance between pluripotency and cell differentiation in embryonic stem cells [14]. Moreover, Cerubidine (Daunorubicin HCl, Rubidomycin HCl) Cerubidine (Daunorubicin HCl, Rubidomycin HCl) BAF47/INI1 is usually a tumor suppressor gene [15], since constitutive mutations have been associated with a strong predisposition to develop malignant rhabdo?d tumors, some of which could be of myogenic origin [16], [17], [18]. One consequence Cerubidine (Daunorubicin HCl, Rubidomycin HCl) of BAF47/INI1 loss is the activation of gene expression programs that are associated with proliferation [19], [20], [21], [22]. However, other studies report that BAF47/INI1 is also implicated in differentiation of hepatocytes [23] and adipocytes [24]. Among other BAF subunits, BAF53/ARP4/ACTL6 is usually a nuclear Actin Related Protein play different roles [25]. Indeed, its interaction with the core SWI/SNF complex is required for the maximal ATPase activity of BRG1 and for the association of the SWI/SNF complex with chromatin [26], [27]. Two distinct BAF53 genes have been described, BAF53a and BAF53b. This subunit is an essential regulator of adult stem cell function [25], [28]. BAF53 is usually involved in self renewal of progenitor and.