HDAC2 Mediates Gene Inactivating of p16INK4a and Promotes Gastric Carcinogenesis by Enhancing Cell Survival and Growth
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ABSTRACT: To investigate the specific roles of HDAC2 in the development of gastric cancer, we employed large-scale gene expression analysis to identify the molecular signature that may affect enabling characteristics of cancer cells. Differentially expressed genes were analyzed on the MKN-1 cells transfected with HDAC2 shRNAs, and recapitulated molecular signatures that related to hallmarks of cancer. DNA methylation of p16INK4a promoter region was assessed by methylation specific polymerase chain reaction. Recruiting the HDAC2 at the p16INK4a promoter was identified using chromatin immunoprecipitation assay. RNA interference-mediated protein knockdown method was used to investigate oncogenic potential of HDAC2 in in vitro and in vivo gastrocarcinogenesis of MKN-1 cells. RNA interference-mediated protein knockdown versus mock treatment
Project description:To investigate the specific roles of HDAC2 in the development of gastric cancer, we employed large-scale gene expression analysis to identify the molecular signature that may affect enabling characteristics of cancer cells. Differentially expressed genes were analyzed on the MKN-1 cells transfected with HDAC2 shRNAs, and recapitulated molecular signatures that related to hallmarks of cancer. DNA methylation of p16INK4a promoter region was assessed by methylation specific polymerase chain reaction. Recruiting the HDAC2 at the p16INK4a promoter was identified using chromatin immunoprecipitation assay. RNA interference-mediated protein knockdown method was used to investigate oncogenic potential of HDAC2 in in vitro and in vivo gastrocarcinogenesis of MKN-1 cells.
Project description:To investigate the specific roles of HDAC2 in the development of liver cancer, we employed large-scale gene expression analysis to identify the molecular signature that may affect enabling characteristics of cancer cells. Differentially expressed genes were analyzed on the Hep3B cells transfected with HDAC2 shRNAs, and recapitulated molecular signatures that related to hallmarks of cancer. With the aim of identifying changes in gene expression following gene knockdown of HDAC2, we performed expression profiling in shRNA expression vector-transfected Hep3B cells, and compared the results to those obtained from vector-transfected Hep3B cells.
Project description:Histone deacetylases (Hdac) remove acetyl groups from proteins, influencing global and specific gene expression. Hdacs control inflammation, as shown by Hdac inhibitor-dependent protection from DSS-induced murine colitis. While tissue-specific Hdac knockouts show redundant and specific functions, little is known of their intestinal epithelial cell (IEC) role. We have shown previously that dual Hdac1/Hdac2 IEC-specific loss disrupts cell proliferation and determination, with decreased secretory cell numbers and altered barrier function. We thus investigated how compound Hdac1/Hdac2 or Hdac2 IEC-specific deficiency alters the inflammatory response. Floxed Hdac1 and Hdac2 and villin-Cre mice were interbred. Compound Hdac1/Hdac2 IEC-deficient mice showed chronic basal inflammation, with increased basal Disease Activity Index (DAI) and deregulated Reg gene colonic expression. DSS-treated dual Hdac1/Hdac2 IEC-deficient mice displayed increased DAI, histological score, intestinal permeability and inflammatory gene expression. In contrast to double knockouts, Hdac2 IEC-specific loss did not affect IEC determination and growth, nor result in chronic inflammation. However, Hdac2 disruption protected against DSS colitis, as shown by decreased DAI, intestinal permeability and caspase-3 cleavage. Hdac2 IEC-specific deficient mice displayed increased expression of IEC gene subsets, such as colonic antimicrobial Reg3b and Reg3g mRNAs, and decreased expression of immune cell function-related genes. Our data show that Hdac1 and Hdac2 are essential IEC homeostasis regulators. IEC-specific Hdac1 and Hdac2 may act as epigenetic sensors and transmitters of environmental cues and regulate IEC-mediated mucosal homeostatic and inflammatory responses. Different levels of IEC Hdac activity may lead to positive or negative outcomes on intestinal homeostasis during inflammation Total RNAs from the colon of three control and three Hdac2 IEC-specific knockout mice were isolated with the Rneasy kit (Qiagen, Mississauga, ON, Canada).
Project description:Expression profiles of 17 melanoma cell lines were analysed to identify genes differentially expressed between cell lines harbouring wild-type or mutant p16INK4A. Relevant paper: Pavey et al. (2007). Note: all of these cell lines contained wild-type p14ARF, so that the transcriptional effects of p16INk4A could be determined without interference from p14ARF. Keywords: Affymetrix Hu133_Plus microarrays
Project description:Expression profiles of 17 melanoma cell lines were analysed to identify genes differentially expressed between cell lines harbouring wild-type or mutant p16INK4A. Relevant paper: Pavey et al. (2007). Note: all of these cell lines contained wild-type p14ARF, so that the transcriptional effects of p16INk4A could be determined without interference from p14ARF. Experiment Overall Design: The aim of this study was to identify genes which are transcriptional targets of p16INK4A in melanoma.
Project description:p16INK4A inhibits the CDK4/6 kinases and is therefore an important cell cycle regulator. Accumulation of p16INK4A in response to oncogenic transformation leads to cellular senescence and it is therefore frequently lost in cancer. p16INK4A is also known to accumulate under conditions of cellular oxidative stress and therefore could potentially be regulated by redox signaling, which is a form of signal transduction that is mediated by the reversible oxidation of cysteine-thiol side chains in proteins. We found that oxidation of the single cysteine residue in p16INK4A in human cells occurs under relatively mild oxidizing conditions and that this leads to disulfide dependent dimerization. p16INK4A is a well-characterized all alpha-helical protein, but we find that upon cysteine-dependent dimerization, p16INK4A undergoes a dramatic structural rearrangement and forms aggregates that have the typical features of amyloid fibrils, including binding of diagnostic dyes, presence of cross-β sheet structure, and typical dimensions found in electron microscopy. We find that p16INK4A amyloid formation abolishes its function as a CDK4/6 inhibitor in human cells. Taken together, these observations mechanistically link the cellular redox state to the inactivation of p16INK4A through the formation of amyloid fibrils.
Project description:Acetylation and deacetylation of histones and other proteins depend on the opposing activities of histone acetyltransferases and histone deacetylases (HDACs), leading to either positive or negative gene expression changes. The use of HDAC inhibitors (HDACi) has uncovered a role for HDACs in the control of proliferation, apoptosis and inflammation. However, little is known of the roles of specific HDACs in intestinal epithelial cells (IEC). We investigated the consequences of ablating both Hdac1 and Hdac2 in murine IECs gene expression. HDAC1 and HDAC2 conditionally mutated mice were provided by Dr EN Olson (University of Texas Southwestern Medical Center, Dallas, TX) (Montgomery et al., 2007). Floxed HDAC1 and HDAC2 mice were crossed with villin-Cre transgenic mice to insure specific intestinal epithelial cell gene deletion (Madison et al., 2002). Total RNAs from the colon of three control and three HDAC1/2 IEC-specific knockout mice were isolated with the Rneasy kit (Qiagen, Mississauga, ON, Canada).
Project description:Dramatic changes in chromatin structure and histone modification occur during oocyte growth, as well as a global cessation of transcription. The role of histone modifications in these processes is poorly understood. We report the effect of conditionally deleting Hdac1 and Hdac2 on oocyte development. Deleting either gene has little or no effect on oocyte development, whereas deleting both genes results in follicle development arrest at the secondary follicle stage. This developmental arrest is accompanied by substantial perturbation of the transcriptome and a global reduction in transcription even though histone acetylation is markedly increased. There is no apparent change in histone repressive marks but there is a pronounced decrease in histone H3K4 methylation, an activating mark. The decrease in H3K4 methylation is likely due to increased expression of Kdm5b because RNAi-mediated targeting of Kdm5b in double mutant oocytes results in an increase in H3K4 methylation. An increase in TRP53 acetylation also occurs in mutant oocytes and may contribute to the observed increased incidence of apoptosis. Taken together, these results suggest seminal roles of acetylation of histone and non-histone proteins in oocyte development. We used microarrays to detail the global programme of gene expression underlying oocyte development and identified distinct classes of regulated genes during this process. Total RNA was extracted from 80 oocytes isolated from mice 12 days-of-age using the PicoPure RNA kit (Arcturus), amplified with the Ovation Pico WTA system (NuGen), and then fragmented and labeled with the FL-OvationTM cDNA Biotin Module V2 (NuGen). Four independent biological replicates were hybridized to Affymetrix GeneChip Mouse 1.1 ST microarrays (http://www.affymetrix.com/). Raw microarray data were analyzed as previously described using MAS5, GeneSpring v7, SAM and EASE software (56). A 1.4-fold cutoff was used for EASE analysis; four biological replicates provide sufficient statistical power and confidence to detect a 1.4-fold change in transcript abundance
Project description:We have performed quantitative proteomic TandemMassTag to investigate proteomic changes after deletion of epigenetic eraser genes Hdac1 and Hdac2 in intestinal epithelial cells. Both HDAC1 and HDAC2 are epigenetic erasers that drive specific and redundant gene expression patterns, in part by removing acetyl groups on histones. Deletion of these Hdac in intestinal epithelial cell (IEC) in vivo alters intestinal homeostasis, dependent on the Hdac deleted and the level of expression of both. To determine the specific IEC function of HDAC1 and HDAC2, we have performed transcriptomic and quantitative proteomic approaches on IEC deficient in Hdac1 and Hdac2. We have defined changes in both mRNA and protein expression patterns affecting IEC differentiation. We have identified IEC Hdac1- and Hdac2-dependent common as well as specific pathways and biological processes. These findings uncover unrecognized similarities and differences between Hdac1 and Hdac2 in IEC.
Project description:We have exploited organoid SILAC approaches that we have previously developed (A SILAC-Based Method for Quantitative Proteomic Analysis of Intestinal Organoids.- Gonneaud A, Jones C, Turgeon N, Lévesque D, Asselin C, Boudreau F, Boisvert FM. -Sci Rep. 2016 Nov 30;6:38195. doi: 10.1038/srep38195) to investigate proteomic changes after deletion of epigenetic eraser genes Hdac1 and Hdac2 in enteroids. Both HDAC1 and HDAC2 are epigenetic erasers that drive specific and redundant gene expression patterns, in part by removing acetyl groups on histones. Deletion of these Hdac in intestinal epithelial cell (IEC) in vivo alters intestinal homeostasis, dependent on the Hdac deleted and the level of expression of both. To determine the intrinsic specific IEC function of HDAC1 and HDAC2, we have performed transcriptomic and quantitative proteomic approaches on enteroids deficient in Hdac1 or Hdac2. We have defined changes in both mRNA and protein expression patterns affecting IEC differentiation. We have identified IEC Hdac1- and Hdac2-dependent common as well as specific pathways and biological processes. These findings uncover unrecognized similarities and differences between Hdac1 and Hdac2 in IEC.