Dataset Information

MRNA profiles of U251 cells with endogenous Gcn5 depletion and reconstituted expression of WT Flag-rGcn5 or Flag-rGcn5 Y645A / endogenous DLST depletion and reconstituted expression of WT V5-rDLST or V5-rDLST R224A/K226E

ABSTRACT: Purpose: The goals of this study are to compare NGS-derived transcriptome profiling (RNA-seq) of U251 cells with endogenous Gcn5 depletion and reconstituted expression of WT Flag-rGcn5 or Flag-rGcn5 Y645A / endogenous DLST depletion and reconstituted expression of WT V5-rDLST or V5-rDLST R224A/K226E Transcriptomes. And quantitatively analyze the cell signaling pathways that regulated by the studied mutants. Methods: total mRNA was extracted from U251 cells with endogenous Gcn5 depletion and reconstituted expression of WT Flag-rGcn5 or Flag-rGcn5 Y645A / endogenous DLST depletion and reconstituted expression of WT V5-rDLST or V5-rDLST R224A/K226E.llumina compatible libraries were prepared by using the KAPA Stranded mRNA-Seq Library Preparation Kit for Illumina® platforms (KAPA Biosystems). In brief, 250 ng of total RNA was enriched for poly-A-tailed mRNA by using Kapa’s mRNA Capture beads. Poly-A-enriched RNA was fragmented to a median size of 150 bp by using chemical fragmentation and converted into double-stranded cDNA with dUTP incorporated into the second cDNA strand. The ends of the double-stranded cDNA were polished, 5’-phosphorylated, and 3’-A-tailed for the ligation of indexed adapters. Adapter-ligated DNA fragments were amplified by 8 cycles of PCR. The strand with incorporated dUTP was not amplified. The resulting libraries were quantified by qPCR and assessed for size distribution by using the 4200 TapeStation (Agilent Technologies), and then multiplexed, 4 per pool, and sequenced on the Illumina’s NextSeq500 by using the mid-output, 75-bp paired-end read format. Results: Using an optimized data analysis workflow, we mapped about 50 million sequence reads per sample to the human genome and quantified the expression of protein coding genes in the U251 cells of WT Gcn5 and Gcn5 Y645A mutant/WT DLST and DLST R224A/K226E mutant. Altered expression of 3 genes was confirmed with qRT–PCR, demonstrating the high degree of sensitivity of the RNA-seq method. Conclusions: Our study represents the first detailed analysis of U251 cells with endogenous Gcn5 depletion and reconstituted expression of WT Flag-rGcn5 or Flag-rGcn5 Y645A / endogenous DLST depletion and reconstituted expression of WT V5-rDLST or V5-rDLST R224A/K226E Transcriptomes. The optimized data analysis workflows reported here should provide a framework for comparative investigations of expression profiles. Our results show that Gcn5 Y45A mutant and DLST R224A/K226E mutant, which reduce histone H3 K79 succinylation, can regulate several cell signaling pathways that important for cancer cell proliferation.

ORGANISM(S): Homo sapiens

PROVIDER: GSE98050 | GEO | 2017/12/13

SECONDARY ACCESSION(S): PRJNA383809

REPOSITORIES: GEO

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Project description:Myocyte enhancer factor 2B (MEF2B) is a transcription factor with somatic mutation hotspots at K4, Y69 and D83 in diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). The recurrence of these mutations indicates that they may drive lymphoma development. However, inferring the mechanisms by which they may drive lymphoma development was complicated by our limited understanding of MEF2B’s normal functions. To expand our understanding of the cellular activities of wildtype (WT) and mutant MEF2B, I developed and addressed two hypotheses: (1) identifying genes regulated by WT MEF2B will allow identification of cellular phenotypes affected by MEF2B activity and (2) contrasting the DNA binding sites, effects on gene expression and effects on cellular phenotypes of mutant and WT MEF2B will help refine hypotheses about how MEF2B mutations may contribute to lymphoma development. To address these hypotheses, I first identified genome-wide WT MEF2B binding sites and transcriptome-wide gene expression changes mediated by WT MEF2B. Using these data I identified and validated novel MEF2B target genes. I found that target genes of MEF2B included the cancer genes MYC, TGFB1, CARD11, NDRG1, RHOB, BCL2 and JUN. Identification of target genes led to findings that WT MEF2B promotes expression of mesenchymal markers, promotes HEK293A cell migration, and inhibits DLBCL cell chemotaxis. I then investigated how K4E, Y69H and D83V mutations change MEF2B’s activity. I found that K4E, Y69H and D83V mutations decreased MEF2B DNA binding and decreased MEF2B’s capacity to promote gene expression in both HEK293A and DLBCL cells. These mutations also reduced MEF2B’s capacity to alter HEK293A and DLBCL cell movement. From these data, I hypothesize that MEF2B mutations may promote DLBCL and FL development by reducing expression of MEF2B target genes that would otherwise function to help confine germinal centre B-cells to germinal centres. Overall, my research demonstrates how observations from genome-scale data can be used to identify cellular effects of candidate driver mutations. Moreover, my work provides a unique resource for exploring the role of MEF2B in cell biology: I map for the first time the MEF2B ‘regulome’, demonstrating connections between a relatively understudied transcription factor and genes significant to oncogenesis. ChIP-seq was performed using a V5 antibody on cells expressing V5 tagged WT and mutant MEF2B. Two biological replicates were performed on WT, K4E, Y69H and D83V MEF2B-V5 cells.

Dataset Information

MRNA profiles of U251 cells with endogenous Gcn5 depletion and reconstituted expression of WT Flag-rGcn5 or Flag-rGcn5 Y645A / endogenous DLST depletion and reconstituted expression of WT V5-rDLST or V5-rDLST R224A/K226E

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