Dual role of Brg chromatin remodeling factor in Sonic hedgehog signaling during neural development

Abstract

Sonic hedgehog (Shh) signaling plays diverse roles during animal development and adult tissue homeostasis through differential regulation of Gli family transcription factors. Dysregulated Shh signaling activities have been linked to birth defects and tumorigenesis. Here we report that Brg, an ATP-dependent chromatin remodeling factor, has dual functions in regulating Shh target gene expression. Using a Brg conditional deletion in Shh-responding neural progenitors and fibroblasts, we demonstrate that Brg is required both for repression of the basal expression and for the activation of signal-induced transcription of Shh target genes. In developing telencephalons deficient for Brg, Shh target genes were derepressed, whereas Brg-deleted cerebellar granule neuron precursors failed to respond to Shh to increase their proliferation. The repressor function of Brg was mediated through Gli3 and both the repressor and activator functions of Brg appeared to be independent of its ATPase activity. Furthermore, Brg facilitates Gli coactivator histone deacetylase (HDAC) binding to the regulatory regions of Shh target genes, providing a possible mechanism for its positive role in Shh signaling. Our results thus reveal that a complex chromatin regulation mechanism underlies the precise transcription outcomes of Shh signaling and its diverse roles during development.Gli proteins | neural development | SWI/SNF complexes | transcription regulation | signal transduction

Selective Recognition of H3.1K36 Dimethylation/H4K16 Acetylation Facilitates the Regulation of All-trans-retinoic Acid (ATRA)-responsive Genes by Putative Chromatin Reader ZMYND8

“…Peptides purchased from EpiCypher were as follows: H3.3(22-44) (12-0020); H3.3K36Me1 (12-0022); H3.3K36Me2 (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23), and H3.3K36Me3 (12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24).…”

“…Co-IP-Cross-linked cells were subjected to co-IP as delineated elsewhere (20). In brief, after cross-linking the cells were lysed with 50 mM HEPES (pH 7.5), 150 mM NaCl, 1.5 mM MgCl 2 , 1 mM EDTA, 1 mM EGTA, 1% Triton X-100, 0.5% sodium deoxycholate, 5% glycerol, 1 mM DTT, 2 mM PMSF, 1 mM trichostatin A, 5 mM sodium butyrate, and complete protease inhibitor mixture and incubated on ice for 1 h followed by centrifugation at 13,000 rpm for 10 min at 4°C.…”

Autism-Associated Chromatin Regulator Brg1/SmarcA4 Is Required for Synapse Development and Myocyte Enhancer Factor 2-Mediated Synapse Remodeling

“…The experiments were repeated at least three times. Standard errors were calculated according to a previously described method (37). The sequences of all the primers are listed in Table S3 in the supplemental material.…”

“…Chromatin immunoprecipitation (ChIP) experiments were performed as described previously (37,42). Tissue disrupted by Dounce homogenization or dissociated cells were cross-linked with PFA and sonicated to fragments (200 to 500 bp).…”

Gli1/DNA interaction is a druggable target for Hedgehog-dependent tumors

“…Gli proteins harbor a five zinc finger (ZF) region in which ZF4 and ZF5 domains bind target DNA in a sequence-specific way, whereas ZF1, ZF2 and ZF3 bind the phosphate backbone and possibly contributed to control binding stability and recruitment of co-regulatory factors (Kinzler & Vogelstein, 1990;Pavletich & Pabo, 1993). A C-terminal region is provided of transactivating function through modulation of chromatin remodeling induced by recruitment of TFIID TATA box-binding proteinassociated factor TAFII31 (Yoon et al, 1998;Bosco-Clément et al, 2013) or HAT and HDAC Malatesta et al, 2013), SWI-SNF5 (Jagani et al, 2010) and SWI/SNF-like Brg/Brmassociated factor (Zhan et al, 2011). In this way, Gli transcription factors behave as the final effectors for the control of specific oncogenic target genes (Aberger & Ruiz I Altaba, 2014).…”