Transcriptome analysis of control and BRG1-depleted 22RV-1 cells with or without PTEN ablation
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ABSTRACT: We conduct transcriptome comparison of control and BRG1-depleted 22RV-1 cells with or without PTEN ablation to gain genomic insights on the biological processes that BRG1 is involved in depend on PTEN deletion. Through unsupervised cluster analysis of differentially expressed genes (DEGs), we found the expressions of 5489 genes were significantly altered in PTEN/BRG1 double knockdown cells, whereas they remained consistent or opposite pattern in control, BRG1-KD and PTEN-KD cells. Differential principal component analysis (PCA) suggested ablation of BRG1 in PTEN-depleted cells forced the cells undergoing a distinct transcriptome as compared to the others. In keeping with these findings, KEGG-DEGs relationship network indicated BRG1 loss in PTEN-deficient cells significantly altered the process related to “Prostate cancer”, “Cell cycle”, “Cell motility” and etc.
Project description:Transposase-accessible chromatin using sequencing (ATAC-seq) assay was performed to compare chromatin open regions (OCRs) between PTEN-KD and PTEN/BRG1-KD 22RV-1 cells. Ablation of BRG1 in PTEN-depleted cells preferentially led to the reductions of OCR at enhancers, but not promoter regions.
Project description:To identify the downstream targets and pathways mediated by BRG1, chromatin immunoprecipitation followed by sequencing (ChIP–seq) was performed in control and PTEN-knockdown 22RV-1 cells. Total 6279 genes showed the enhanced BRG1 occupancies in PTEN-knockdown cells as compared to that in control cells. Genome-wide analysis revealed that PTEN loss lead to increase BRG1 intervals specifically localized at enhancers, but not distal promoter regions. We therefore reasoned ablation of BRG1 might impair enhancer configurations in PTEN-deficient cells.
Project description:The SWI/SNF complex remodels chromatin in an ATP-dependent manner through the ATPase subunits BRG1 and BRM. Chromatin remodeling alters nucleosome structure to change gene expression, however aberrant remodeling and gene expression can result in cancer. The function and localization on chromatin of the SWI/SNF complex depends on the protein makeup of the complex. Here we report the protein-protein interactions of wild-type BRG1 or mutant BRG1 in which the HSA domain has been deleted (BRG1-HSA). We demonstrate the interaction of BRG1 with most SWI/SNF complex members and a failure of a number of these members to interact with BRG1-HSA. These results demonstrate that the HSA domain of BRG1 is a critical interaction platform for the correct formation of SWI/SNF remodeling complexes.
Project description:Brahma related gene 1 (BRG1), a catalytic ATPase subunit of SWI/SNF chromatin remodeling complexes, is silenced in approximately 10% of human pancreatic ductal adenocarcinomas (PDA). We previously showed that BRG1 inhibits the formation of intraductal pancreatic mucinous neoplasm (IPMN) and IPMN-derived PDA from ductal cells. However, the role of BRG1 in pancreatic intraepithelial neoplasia (PanIN) from acinar cells remains elusive. Here, we investigated the role of BRG1 in PanIN initiation and maintenance and its underlying mechanisms. Exclusive elimination of Brg1 in acinar cells of Ptf1a-CreER; KrasG12D; Brg1f/f (KBC) mice impaired the formation of acinar-to-ductal metaplasia (ADM) and PanIN independent of the presence of p53 mutation. We found that Sox9 expression was down-regulated in both Brg1-depleted acinar cell explants and BRG1-depleted ADMs/PanINs. Sox9 overexpression rescued this PanIN-attenuated phenotype in KBC mice. Furthermore, Brg1-deletion in established PanIN by using an inducible dual recombinase system resulted in regression of the lesions in mice. Finally, expression of BRG1 and SOX9 was also positively correlated in human PanIN-derived PDAs. In summary, BRG1 is critical for both initiation and maintenance of PanIN. Mechanistically, this is mediated through positive regulation of SOX9 expression. Thus, the BRG1/SOX9 axis is a potential target for the prevention of PanIN-derived PDA.
Project description:Brg1 is a subunit of SWI/SNF chromatin remodeling complex. To clarify the role of Brg1 for the progression and metastasis of pancreatic ductal adenocarcinoma (PDAC), we generated a PDAC mouse model with a dual recombinase system (Brg1 lox/lox; Pdx1-Flp; Kras FSF-G12D; Trp53 frt/frt; Rosa26 FSF-CreERT2) which enabled to ablate Brg1 in established PDAC with tamoxifen treatment. We established cancer cell lines derived from PDAC tumors developed in those mice and investigated the effect of Brg1 ablation on PDAC cell proliferation and metastasis. In order to determine the genes expression in Brg1-deleted mouse PDAC cells, we conducted a transcriptomic analysis using microarray using Brg1 wild type and Brg1-deleted mouse PDAC cells.
Project description:Brg1 is a subunit of SWI/SNF chromatin remodeling complex. To clarify the role of Brg1 for the progression and metastasis of pancreatic ductal adenocarcinoma (PDAC), we generated a PDAC mouse model with a dual recombinase system (Brg1 lox/lox; Pdx1-Flp; Kras FSF-G12D; Trp53 frt/frt; Rosa26 FSF-CreERT2) which enabled to ablate Brg1 in established PDAC with tamoxifen treatment. We established cancer cell lines derived from PDAC tumors developed in those mice and investigated the effect of Brg1 ablation on PDAC cell proliferation and metastasis. In order to determine the genes that Brg1 directly regulates, we conducted a chromatin immunoprecipitation coupled with deep sequencing (ChIP-seq) analysis for Brg1 and histone modifications (H3K27ac and H3K27me3) using Brg1 wild type and Brg1-deleted mouse PDAC cells.
Project description:We report that BRG1, an ATPase subunit of the SWI/SNF chromatin remodeling complex, was required for the homeostatic maintenance of colonic epithelial cells (IECs) to prevent the inflammation and tumorigenesis. Consistent with the reduced BRG1 expression in IBD patients, adult mice with IEC ablation of BRG1 developed spontaneous colitis and exhibited increased susceptibility to mutagen-induced tumor growth. Conversely, BRG1 overexpression protected the mice from DSS-induced epithelial damage and subsequent oncogenesis. Mechanistically, BRG1 emerged as a key regulator that directly governs the transcription of Atg16l1, Ambra1, Atg7 and Wipi2, which are important for autophagosome biogenesis. Thus, defective autophagy in BRG1-deficient IECs resulted in excess reactive oxygen species (ROS), which led to the defects in cellular apoptosis and barrier integrity.
Project description:Here we show that epithelial BRG1, the catalytic subunit of SWI/SNF complex is critical for colitis and colitis-associated-cancer. Depletion of BRG1 in colonrectal epithelial cells make mice develop Spontaneous colitis. To dissect underlying mechanism, we conducted gene expression profile analysis (RNA-Seq) by using primary colonrectal epithelial cells isolated from BRG1CTRL and BRG1IEC-KO(Tamoxifen induced BRG1 knock-out) mice to gain molecular insights into the affected biological processes. To this end, colorectal epithelial cells were isolated after 14 days of tamoxifen treatment, on which day BRG1-depleted mice showed little morphological defects in colon in comparison with control littermates. IECs were isolated by EDTA isolation buffer. Each sample contains pooled mRNA from 3 mice, and was subjected to Hiseq RNA-Seq, performed by BGI Tech Solutions Co., Ltd.