Chromatin, Metabolism and Cell Fate

  • Buschbeck_Group_Statue_11_2017
ICO - German Trias i Pujol

Josep Carreras Leukaemia Research Institute
Edifici IMPPC
Can Ruti CampusCtra de Can Ruti
Camí de les Escoles s/n
08916 Badalona, Barcelona, Spain

Office 2-17 Lab 2-15 (second floor)



Epigenetic information is written in chromatin. But how exactly do epigenetic mechanisms operate on the molecular level? How do chromatin alterations contribute to cell fate transitions? How does the environment influence these processes? And how does the metabolic state of a cell impact on its chromatin structure and its epigenetic memory?

These are questions we address in the lab. Studying stem cells and cancer we focus on molecular aspects of epigenetic regulation and on the question whether we can translate this knowledge into diagnostic and therapeutic tools for the management of diseases such as leukemia and myelodysplastic syndrome.


In our scientific approach we combine biochemical techniques, genetic manipulation of cell cultures and ultrasequencing of enriched chromatin fractions to address mechanistic and functional aspects of epigenetics. As model system for cell differentiation we are using embryonic stem cells, myoblasts and hematopoietic cells. Key findings are validated in vivo. For the study of cancer we combine established cell lines, primary cultures and other patient samples.

Ongoing projects in the lab fall in one or several of three main themes:

  • The link between metabolism and epigenetic regulation.
  • The regulation and molecular function of histone variants.
  • Chromatin as drug target in myelodysplastic syndrome (MDS) and leukemia.

These are two examples of ongoing projects.

Chromatin modifiers as drug targets in MDS and cancer

Intrinsic and acquired resistances are the main reason for failure of current cancer treatments. For best treatments initial responses are limited to less than 50% of patients and virtually all responders eventually relapse and progress. The main goal of this study is to identify urgently needed response-predicting biomarkers and new combinatorial drug targets to increase rate and durability of response.

We coordinate the RESPONSE network (PIE16/00011) that brings together clinical and experimental groups. Together we we focus on three major cancers and their current treatments: advanced colorectal and lung cancer treated with chemotherapy and high-risk myelodysplastic syndrome treated with azacitidine.

To achieve our goals we combine the power of genetic screening technology with the analysis of highly informative clinical sample collections. We focus on transcriptional and chromatin regulators as a promising yet underexplored group of drug effectors. We examine drug-sensitizing genes and pathways with the aim to determine new drug targets for combinational therapy. Our long-term goal is to maximally advance the preclinical studies enabling the design of well-informed clinical trials. Using transcriptomic and epigenomic techniques we will further dissect the molecular function of most relevant effector genes.


The regulation and function of the macroH2A histone variants

Histones form the protein core of the nucleosome, which is the modular building block of chromatin structure. Histone variants endow chromatin with unique properties and show a specific genomic distribution. The histone variants macroH2A are unique in having a tripartite structure consisting of a N-terminal histone-fold, an intrinsically unstructured linker domain and a C-terminal macro domain. Recently, we have made two major discoveries. First, macroH2A proteins have a major role in the nuclear organization (Douet et al., 2017, JCS). This has the potential to explain how these proteins can act as tumor suppressors, promoters of differentiation and barriers to somatic ecll reprogramming (discussed in Buschbeck and Hake, 2017, Nature Reviews).

Second, we have identified the macroH2A1.1 isoform to be part of amolecular mechanism allowing cells to couple the metabolic requirements between distant organelles such as nucleus and mitochondria. Specifically, we found that macroH2A1.1 binds nuclear PARP1 and dampens its NAD+ consumption thereby creating a buffer of NAD+ precursors facilitating NAD+ dependent reactions in other organelles, such as respiration in mitochondria (Posavec Marjanovic, Hurtado-Bagès et al., 2017, NSMB). As co-coordinators of the MSCA ITN 'ChroMe', we are further pursuing additional research lines at the intersection of the chromatin and metabolism fields.



Selected publications

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.
Més informació
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 Set 2017, . Epub 15 Set 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.
Més informació
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.
Més informació
Buschbeck M, Hake SB

Variants of core histones and their roles in cell fate decisions, development and cancer.

Nat. Rev. Mol. Cell Biol. 1 Feb 2017, . Epub 1 Feb 2017
Histone variants endow chromatin with unique properties and show a specific genomic distribution that is regulated by specific deposition and removal machineries. These variants - in particular, H2A.Z, macroH2A and H3.3 - have important roles in early embryonic development, and they regulate the lineage commitment of stem cells, as well as the converse process of somatic cell reprogramming to pluripotency. Recent progress has also shed light on how mutations, transcriptional deregulation and changes in the deposition machineries of histone variants affect the process of tumorigenesis. These alterations promote or even drive cancer development through mechanisms that involve changes in epigenetic plasticity, genomic stability and senescence, and by activating and sustaining cancer-promoting gene expression programmes.
Més informació
Diesch J, Zwick A, Garz AK, Palau A, Buschbeck M, Götze KS

A clinical-molecular update on azanucleoside-based therapy for the treatment of hematologic cancers.

Clin Epigenetics 2016, 8 71. Epub 21 Jun 2016
The azanucleosides azacitidine and decitabine are currently used for the treatment of acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) in patients not only eligible for intensive chemotherapy but are also being explored in other hematologic and solid cancers. Based on their capacity to interfere with the DNA methylation machinery, these drugs are also referred to as hypomethylating agents (HMAs). As DNA methylation contributes to epigenetic regulation, azanucleosides are further considered to be among the first true "epigenetic drugs" that have reached clinical application. However, intriguing new evidence suggests that DNA hypomethylation is not the only mechanism of action for these drugs. This review summarizes the experience from more than 10 years of clinical practice with azanucleosides and discusses their molecular actions, including several not related to DNA methylation. A particular focus is placed on possible causes of primary and acquired resistances to azanucleoside treatment. We highlight current limitations for the success and durability of azanucleoside-based therapy and illustrate that a better understanding of the molecular determinants of drug response holds great potential to overcome resistance.
Més informació
Palau A, Mallo M, Palomo L, Rodríguez-Hernández I, Diesch J, Campos D, Granada I, Juncà J, Drexler HG, Solé F, Buschbeck M

Immunophenotypic, cytogenetic, and mutational characterization of cell lines derived from myelodysplastic syndrome patients after progression to acute myeloid leukemia.

Genes Chromosomes Cancer Mar 2017, 56 (3) 243-252. Epub 21 Nov 2016
Leukemia cell lines have been widely used in the hematology field to unravel mechanistic insights and to test new therapeutic strategies. Myelodysplastic syndromes (MDS) comprise a heterogeneous group of diseases that are characterized by ineffective hematopoiesis and frequent progress to acute myeloid leukemia (AML). A few cell lines have been established from MDS patients after progression to AML but their characterization is incomplete. Here we provide a detailed description of the immunophenotypic profile of the MDS-derived cell lines SKK-1, SKM-1, F-36P; and MOLM-13. Specifically, we analyzed a comprehensive panel of markers that are currently applied in the diagnostic routine for myeloid disorders. To provide high-resolution genetic data comprising copy number alterations and losses of heterozygosity we performed whole genome single nucleotide polymorphism-based arrays and included the cell line OHN-GM that harbors the frequent chromosome arm 5q deletion. Furthermore, we assessed the mutational status of 83 disease-relevant genes. Our results provide a resource to the MDS and AML field that allows researchers to choose the best-matching cell line for their functional studies. © 2016 Wiley Periodicals, Inc.
Més informació
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Current projects


Responsable:Marcus Buschbeck
Data d'inici:01/01/2016
Data de finalització:31/12/2018

Chromatin-metabolism interactions as targets for healthy living (ChroMe)

Responsable:Marcus Buschbeck
Data d'inici:01/03/2016
Data de finalització:29/02/2020


Responsable:Marcus Buschbeck
Data d'inici:01/01/2017
Data de finalització:31/12/2019

Previous projects

Drug repositioning as a fast and cost effective approach to personalized therapies. A pilot study on myelodysplastic syndrome and acute myeloid leukaemia

Responsable:Marcus Buschbeck
Data d'inici:28/02/2014
Data de finalització:31/03/2016

Plan Nacional - Epigenetic Regulators of Stem Cell Function

Responsable:Marcus Buschbeck
Data d'inici:01/01/2013
Data de finalització:31/12/2015

Dissecting the Role of Polycomb Complexes in the Pathogenesis of Myelodysplastic Syndromes (MDS) and the Evolution to Acute Myeloid Leukemia (DJCLS R 14/16)

Responsable:Marcus Buschbeck
Codi:DJCLS R 14/16
Data d'inici:01/08/2015
Data de finalització:31/07/2017

How does the histone variant macroH2A regulate muscle metabolism in health and disease?

Responsable:Marcus Buschbeck
Data d'inici:16/02/2015
Data de finalització:26/10/2017