Research publications

Found 46 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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Kozlowski M, Corujo D, Hothorn M, Guberovic I, Mandemaker IK, Blessing C, Sporn J, Gutierrez-Triana A, Smith R, Portmann T, Treier M, Scheffzek K, Huet S, Timinszky G, Buschbeck M, Ladurner AG

MacroH2A histone variants limit chromatin plasticity through two distinct mechanisms.

EMBO Rep. Oct 2018, 19 (10) . Epub 3 Sep 2018
MacroH2A histone variants suppress tumor progression and act as epigenetic barriers to induced pluripotency. How they impart their influence on chromatin plasticity is not well understood. Here, we analyze how the different domains of macroH2A proteins contribute to chromatin structure and dynamics. By solving the crystal structure of the macrodomain of human macroH2A2 at 1.7 Å, we find that its putative binding pocket exhibits marked structural differences compared with the macroH2A1.1 isoform, rendering macroH2A2 unable to bind ADP-ribose. Quantitative binding assays show that this specificity is conserved among vertebrate macroH2A isoforms. We further find that macroH2A histones reduce the transient, PARP1-dependent chromatin relaxation that occurs in living cells upon DNA damage through two distinct mechanisms. First, macroH2A1.1 mediates an isoform-specific effect through its ability to suppress PARP1 activity. Second, the unstructured linker region exerts an additional repressive effect that is common to all macroH2A proteins. In the absence of DNA damage, the macroH2A linker is also sufficient for rescuing heterochromatin architecture in cells deficient for macroH2A.
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Lo Re O, Douet J, Buschbeck M, Fusilli C, Pazienza V, Panebianco C, Castracani CC, Mazza T, Li Volti G, Vinciguerra M

Histone variant macroH2A1 rewires carbohydrate and lipid metabolism of hepatocellular carcinoma cells towards cancer stem cells.

Epigenetics 30 Aug 2018, . Epub 30 Aug 2018
Hepatocellular carcinomas (HCCs) contain a sub-population of cancer stem cells (CSCs) that are responsible for tumor relapse, metastasis, and chemoresistance. We recently showed that loss of macroH2A1, a variant of the histone H2A and an epigenetic regulator of stem-cell function, in HCC leads to CSC-like features such as resistance to chemotherapeutic agents and growth of large and relatively undifferentiated tumors in xenograft models. These HCC cells silenced for macroH2A1 also exhibited stem-like metabolic changes consistent with enhanced glycolysis. However, there is no consensus as to the metabolic characteristics of CSCs that render them adaptable to microenvironmental changes by conveniently shifting energy production source or by acquiring intermediate metabolic phenotypes. Here, we assessed long-term proliferation, energy metabolism, and central carbon metabolism in human hepatoma HepG2 cells depleted in macroH2A1. MacroH2A1-depleted HepG2 cells were insensitive to serum exhaustion and showed two distinct, but interdependent changes in glucose and lipid metabolism in CSCs: (1) massive upregulation of acetyl-coA that is transformed into enhanced lipid content and (2) increased activation of the pentose phosphate pathway, diverting glycolytic intermediates to provide precursors for nucleotide synthesis. Integration of metabolomic analyses with RNA-Seq data revealed a critical role for the Liver X Receptor pathway, whose inhibition resulted in attenuated CSCs-like features. These findings shed light on the metabolic phenotype of epigenetically modified CSC-like hepatic cells, and highlight a potential approach for selective therapeutic targeting.
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Dumbovic G, Biayna J, Banús J, Samuelsson J, Roth A, Diederichs S, Alonso S, Buschbeck M, Perucho M, Forcales SV

A novel long non-coding RNA from NBL2 pericentromeric macrosatellite forms a perinucleolar aggregate structure in colon cancer.

Nucleic Acids Res. 20 Jun 2018, 46 (11) 5504-5524.
Primate-specific NBL2 macrosatellite is hypomethylated in several types of tumors, yet the consequences of this DNA hypomethylation remain unknown. We show that NBL2 conserved repeats are close to the centromeres of most acrocentric chromosomes. NBL2 associates with the perinucleolar region and undergoes severe demethylation in a subset of colorectal cancer (CRC). Upon DNA hypomethylation and histone acetylation, NBL2 repeats are transcribed in tumor cell lines and primary CRCs. NBL2 monomers exhibit promoter activity, and are contained within novel, non-polyA antisense lncRNAs, which we designated TNBL (Tumor-associated NBL2 transcript). TNBL is stable throughout the mitotic cycle, and in interphase nuclei preferentially forms a perinucleolar aggregate in the proximity of a subset of NBL2 loci. TNBL aggregates interact with the SAM68 perinucleolar body in a mirror-image cancer specific perinucleolar structure. TNBL binds with high affinity to several proteins involved in nuclear functions and RNA metabolism, such as CELF1 and NPM1. Our data unveil novel DNA and RNA structural features of a non-coding macrosatellite frequently altered in cancer.
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Corujo D, Buschbeck M

Post-Translational Modifications of H2A Histone Variants and Their Role in Cancer.

Cancers (Basel) 27 Feb 2018, 10 (3) . Epub 27 Feb 2018
Histone variants are chromatin components that replace replication-coupled histones in a fraction of nucleosomes and confer particular characteristics to chromatin. H2A variants represent the most numerous and diverse group among histone protein families. In the nucleosomal structure, H2A-H2B dimers can be removed and exchanged more easily than the stable H3-H4 core. The unstructured N-terminal histone tails of all histones, but also the C-terminal tails of H2A histones protrude out of the compact structure of the nucleosome core. These accessible tails are the preferential target sites for a large number of post-translational modifications (PTMs). While some PTMs are shared between replication-coupled H2A and H2A variants, many modifications are limited to a specific histone variant. The present review focuses on the H2A variants H2A.Z, H2A.X, and macroH2A, and summarizes their functions in chromatin and how these are linked to cancer development and progression. H2A.Z primarily acts as an oncogene and macroH2A and H2A.X as tumour suppressors. We further focus on the regulation by PTMs, which helps to understand a degree of context dependency.
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Palomo L, Malinverni R, Cabezón M, Xicoy B, Arnan M, Coll R, Pomares H, García O, Fuster-Tormo F, Grau J, Feliu E, Solé F, Buschbeck M, Zamora L

DNA methylation profile in chronic myelomonocytic leukemia associates with distinct clinical, biological and genetic features.

Epigenetics 2018, 13 (1) 8-18. Epub 6 Feb 2018
Chromosomal abnormalities are detected in 20-30% of patients with chronic myelomonocytic leukemia (CMML) and correlate with prognosis. On the mutation level, disruptive alterations are particularly frequent in chromatin regulatory genes. However, little is known about the consequential alterations in the epigenetic marking of the genome. Here, we report the analysis of genomic DNA methylation patterns of 64 CMML patients and 10 healthy controls, using a DNA methylation microarray focused on promoter regions. Differential methylation analysis between patients and controls allowed us to identify abnormalities in DNA methylation, including hypermethylation of specific genes and large genome regions with aberrant DNA methylation. Unsupervised hierarchical cluster analysis identified two main clusters that associated with the clinical, biological, and genetic features of patients. Group 1 was enriched in patients with adverse clinical and biological characteristics and poorer overall and progression-free survival. In addition, significant differences in DNA methylation were observed between patients with low risk and intermediate/high risk karyotypes and between TET2 mutant and wild type patients. Taken together, our results demonstrate that altered DNA methylation patterns reflect the CMML disease state and allow to identify patient groups with distinct clinical features.
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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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Lo Re O, Fusilli C, Rappa F, Van Haele M, Douet J, Pindjakova J, Rocha SW, Pata I, Valčíková B, Uldrijan S, Yeung RS, Peixoto CA, Roskams T, Buschbeck M, Mazza T, Vinciguerra M

Induction of cancer cell stemness by depletion of macrohistone H2A1 in hepatocellular carcinoma.

Hepatology 15 Sep 2017, . Epub 15 Sep 2017
Hepatocellular carcinomas (HCC) contain a sub-population of cancer stem cells (CSCs), which exhibit stem-cell like features and are responsible for tumor relapse, metastasis, and chemoresistance. The development of effective treatments for HCC will depend on a molecular-level understanding of the specific pathways driving CSC emergence and stemness. MacroH2A1 is a variant of the histone H2A and an epigenetic regulator of stem cell function, where it promotes differentiation and, conversely, acts as a barrier to somatic cell reprogramming. Here we focused on the role played by the histone variant macroH2A1 as a potential epigenetic factor promoting CSC differentiation. In human HCC sections we uncovered a significant correlation between low frequencies of macroH2A1 staining and advanced, aggressive HCC subtypes with poorly-differentiated tumor phenotypes. Using HCC cell lines we found that shRNA-mediated macroH2A1 knock-down induces acquisition of CSC-like features, including the growth of significantly larger and less-differentiated tumors when injected into nude mice. MacroH2A1-depleted HCC cells also exhibited reduced proliferation, resistance to chemotherapeutic agents, and stem-like metabolic changes consistent with enhanced hypoxia responses and increased glycolysis. The loss of macroH2A1 increased expression of a panel of stemness-associated genes, and drove hyper-activation of the NF-κBp65 pathway. Blocking phosphorylation of NF-κBp65 on Ser536 inhibited the emergence of CSC-like features in HCC cells knocked-down for macroH2A1.
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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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