Research publications

Found 6 publicacions matching the indicated search criteria.
Hurtado-Bagès S, Posavec Marjanovic M, Valero V, Malinverni R, Corujo D, Bouvet P, Lavigne AC, Bystricky K, Buschbeck M

The Histone Variant MacroH2A1 Regulates Key Genes for Myogenic Cell Fusion in a Splice-Isoform Dependent Manner.

Cells 30 Apr 2020, 9 (5) . Epub 30 Apr 2020
MacroH2A histone variants have functions in differentiation, somatic cell reprogramming and cancer. However, at present, it is not clear how macroH2As affect gene regulation to exert these functions. We have parted from the initial observation that loss of total macroH2A1 led to a change in the morphology of murine myotubes differentiated ex vivo. The fusion of myoblasts to myotubes is a key process in embryonic myogenesis and highly relevant for muscle regeneration after acute or chronic injury. We have focused on this physiological process, to investigate the functions of the two splice isoforms of macroH2A1. Individual perturbation of the two isoforms in myotubes forming in vitro from myogenic C2C12 cells showed an opposing phenotype, with macroH2A1.1 enhancing, and macroH2A1.2 reducing, fusion. Differential regulation of a subset of fusion-related genes encoding components of the extracellular matrix and cell surface receptors for adhesion correlated with these phenotypes. We describe, for the first time, splice isoform-specific phenotypes for the histone variant macroH2A1 in a physiologic process and provide evidence for a novel underlying molecular mechanism of gene regulation.
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Palau A, Garz AK, Diesch J, Zwick A, Malinverni R, Valero V, Lappin K, Casquero R, Lennartsson A, Zuber J, Navarro T, Mills KI, Götze KS, Buschbeck M

Polycomb protein RING1A limits hematopoietic differentiation in myelodysplastic syndromes.

Oncotarget 29 Dec 2017, 8 (70) 115002-115017. Epub 1 Dec 2017
Genetic lesions affecting epigenetic regulators are frequent in myelodysplastic syndromes (MDS). Polycomb proteins are key epigenetic regulators of differentiation and stemness that act as two multimeric complexes termed polycomb repressive complexes 1 and 2, PRC1 and PRC2, respectively. While components and regulators of PRC2 such as ASXL1 and EZH2 are frequently mutated in MDS and AML, little is known about the role of PRC1. To analyze the role of PRC1, we have taken a functional approach testing PRC1 components in loss- and gain-of-function experiments that we found overexpressed in advanced MDS patients or dynamically expressed during normal hematopoiesis. This approach allowed us to identify the enzymatically active component RING1A as the key PRC1 component in hematopoietic stem cells and MDS. Specifically, we found that RING1A is expressed in CD34
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Marjanović MP, Hurtado-Bagès S, Lassi M, Valero V, Malinverni R, Delage H, Navarro M, Corujo D, Guberovic I, Douet J, Gama-Perez P, Garcia-Roves PM, Ahel I, Ladurner AG, Yanes O, Bouvet P, Suelves M, Teperino R, Pospisilik JA, Buschbeck M

MacroH2A1.1 regulates mitochondrial respiration by limiting nuclear NAD(+) consumption.

Nat. Struct. Mol. Biol. 9 Oct 2017, . Epub 9 Oct 2017
Histone variants are structural components of eukaryotic chromatin that can replace replication-coupled histones in the nucleosome. The histone variant macroH2A1.1 contains a macrodomain capable of binding NAD(+)-derived metabolites. Here we report that macroH2A1.1 is rapidly induced during myogenic differentiation through a switch in alternative splicing, and that myotubes that lack macroH2A1.1 have a defect in mitochondrial respiratory capacity. We found that the metabolite-binding macrodomain was essential for sustained optimal mitochondrial function but dispensable for gene regulation. Through direct binding, macroH2A1.1 inhibits basal poly-ADP ribose polymerase 1 (PARP-1) activity and thus reduces nuclear NAD(+) consumption. The resultant accumulation of the NAD(+) precursor NMN allows for maintenance of mitochondrial NAD(+) pools that are critical for respiration. Our data indicate that macroH2A1.1-containing chromatin regulates mitochondrial respiration by limiting nuclear NAD(+) consumption and establishing a buffer of NAD(+) precursors in differentiated cells.
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Douet J, Corujo D, Malinverni R, Renauld J, Sansoni V, Marjanović MP, Cantari'o N, Valero V, Mongelard F, Bouvet P, Imhof A, Thiry M, Buschbeck M

MacroH2A histone variants maintain nuclear organization and heterochromatin architecture.

J. Cell. Sci. 10 Mar 2017, . Epub 10 Mar 2017
Genetic loss-of-function studies in development, cancer and somatic cell reprogramming have suggested that the group of macroH2A histone variants might function through stabilizing the differentiated state by a yet unknown mechanism. Here, we present results demonstrating that macroH2A variants have a major function in maintaining nuclear organization and heterochromatin architecture. Specifically, we find that a substantial amount of macroH2A is associated with heterochromatic repeat sequences. We further identify macroH2A on sites of interstitial heterochromatin decorated by H3K9me3. Loss of macroH2A leads to major defects in nuclear organization including reduced nuclear circularity, disruption of nucleoli and a global loss of dense heterochromatin. Domains formed by repeat sequences when depleted of macroH2A are disorganized, expanded and fragmented and mildly re-expressed. On the molecular level we find that macroH2A is required for the interaction of repeat sequences with the nucleostructural protein Lamin B1. Taken together our results argue that a major function of macroH2A histone variants is to link nucleosome composition to higher order chromatin architecture.
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Cantarino N, Musulen E, Valero V, Peinado MA, Perucho M, Moreno V, Forcales SV, Douet J, Buschbeck M

Downregulation of the Deiminase PADI2 is an Early Event in Colorectal Carcinogenesis and Indicates Poor Prognosis.

Mol. Cancer Res. 8 Jun 2016, . Epub 8 Jun 2016
Peptidyl arginine deiminases (PADIs) are a family of enzymes that catalyze the poorly understood post-translational modification converting arginine residues into citrullines. In this study, the role of PADIs in the pathogenesis of colorectal cancer was investigated. Specifically, RNA expression was analyzed and its association with survival in a cohort of 98 colorectal cancer patient specimens with matched adjacent mucosa and 50 controls from donors without cancer. Key results were validated in an independent collection of tumors with matched adjacent mucosa and by mining of a publicly available expression data set. Protein expression was analyzed by immunoblotting for cell lines or immunohistochemistry (IHC) for patient specimens that further included 24 cases of adenocarcinoma with adjacent dysplasia and 11 cases of active ulcerative colitis. The data indicate that PADI2 is the dominantly expressed PADI enzyme in colon mucosa and is up-regulated during differentiation. PADI2 expression is low or absent in colorectal cancer. Frequently this occurs already at the stage of low-grade dysplasia. Mucosal PADI2 expression is also low in ulcerative colitis. The expression level of PADI2 in tumor and adjacent mucosa correlates with differential survival: low levels associate with poor prognosis.
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Cantariño N, Fernández-Figueras MT, Valero V, Musulén E, Malinverni R, Granada I, Goldie SJ, Martín-Caballero J, Douet J, Forcales SV, Buschbeck M

A cellular model reflecting the phenotypic heterogeneity of mutant HRAS driven squamous cell carcinoma.

Int. J. Cancer 13 Apr 2016, . Epub 13 Apr 2016
Squamous cell carcinomas have a range of histopathological manifestations. The parameters that determine this clinically observed heterogeneity are not fully understood. Here, we report the generation of a cell culture model that reflects part of this heterogeneity. We have used the catalytic subunit of human telomerase hTERT and large T to immortalize primary UV-unexposed keratinocytes. Then, mutant HRAS G12V has been introduced to transform these immortal keratiocytes. When injected into immunosuppressed mice, transformed cells grew as xenografts with distinct histopathological characteristics. We observed three major tissue architectures: solid, sarcomatoid and cystic growth types, which were primarily composed of pleomorphic and basaloid cells but in some cases displayed focal apocrine differentiation. We demonstrate that the cells generated represent different stages of skin cancerogenesis and as such can be used to identify novel tumor-promoting alterations such as the overexpression of the PADI2 oncogene in solid-type SCC. Importantly, the cultured cells maintain the characteristics from the xenograft they were derived from while being amenable to manipulation and analysis. The availability of cell lines representing different clinical manifestations opens a new tool to study the stochastic and deterministic factors that cause case-to-case heterogeneity despite departing from the same set of oncogenes and the same genetic background. This article is protected by copyright. All rights reserved.
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