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The chromatin remodeler Brg1 cooperates with tissue-specific transcription-factors to regulate Sox2 activation via multiple enhancers to establish proneurosensory identity within otic ectoderm

ABSTRACT: Specification of Sox2+ proneurosensory progenitors within otic ectoderm is a prerequisite for the production of sensory cells and neurons for hearing. However, the underlying molecular mechanisms driving this lineage specification remain unknown. Here, we show that Brg1-based SWI/SNF chromatin-remodeling complex interacts with the neurosensory-specific transcriptional regulators Eya1/Six1 to induce Sox2 expression and proneurosensory-lineage specification. Ablation of the ATPase-subunit Brg1 or both Eya1/Six1 results in loss of Sox2 expression and lack of neurosensory identity. Brg1 and Six1 co-occupy three distal 3' Sox2 enhancers and Brg1-recruitment to these regions is disrupted in Eya1- or Six1-null otocyst. Eya1 as a coactivator of Six1 synergistically regulates the activity of these enhancers, which drives expression in otic neurosensory cells in response to binding to Six1. Thus, through interaction with Six1/Eya1, the Brg1-based SWI/SNF complex specifies otic proneurosensory lineage. Furthermore, genome-wide and transcriptome analyses reveal that Brg1 also suppresses expression of non-otic genes.

ORGANISM(S): Mus musculus

PROVIDER: GSE158167 | GEO | 2021/06/04

REPOSITORIES: GEO

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Chromatin remodelers and lineage specific factors interact to target enhancers to establish pro-neurosensory fate within otic ectoderm

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Signal-dependent incorporation of MyoD-BAF60c into Brg1-based SWI/SNF chromatin-remodeling complex

Project description:Tissue-specific transcription factors initiate differentiation toward a specialized cell type by inducing transcription-permissive chromatin modifications at target gene promoters, through the recruitment of the SWI/SNF chromatin-remodeling complex (1, 2). The molecular mechanism that regulates the chromatin re-distribution of SWI/SNF in response to differentiation signals is currently unknown. Here we show that the muscle determination factor MyoD and the SWI/SNF structural sub-unit, BAF60c (SMARCD3), form a complex on the regulatory elements of MyoD-target genes in undifferentiated myoblasts, prior to the activation of gene expression. MyoD-BAF60c complex is devoid of the ATP-dependent enzymatic sub-units Brg1 and Brm, is required for stable MyoD binding to Ebox sequences, and marks the chromatin for signal-dependent recruitment of the SWI/SNF core complex to muscle loci. BAF60c phosphorylation on a conserved threonine by differentiation-activated p38 signalling promotes the incorporation of MyoD-BAF60c into a Brg1-based SWI/SNF complex, which is competent to remodel the chromatin and activates transcription of MyoD-target genes. Our data support an unprecedented two-step model, by which pre-assembled BAF60c-MyoD complex directs the SWI/SNF complex chromatin re-distribution to muscle loci in response to differentiation cues. Differentiation of C2C12 cells individually interfered for BRG1, BAF60B, BAF60C

2011-03-07 | E-GEOD-24573 | biostudies-arrayexpress

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