LINE-1 silencing by retinoblastoma proteins is effected through the nucleosomal and remodeling deacetylase multiprotein complex

Diego E. Montoya-Durango, Kenneth A. Ramos, Pasano Bojang, Lorell Ruiz, Irma Ramos, Kenneth Ramos

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Background: Long Interspersed Nuclear Element-1 (L1) is an oncogenic mammalian retroelement silenced early in development via tightly controlled epigenetic mechanisms. We have previously shown that the regulatory region of human and murine L1s interact with retinoblastoma (RB) proteins to effect retroelement silencing. The present studies were conducted to identify the corepressor complex responsible for RB-mediated silencing of L1. Methods: Chromatin immunoprecipitation and silencing RNA technology were used to identify the repressor complex that silences L1 in human and murine cells. Results: Components of the Nucleosomal and Remodeling Deacetylase (NuRD) multiprotein complex specifically enriched the L1 5'-untranslated DNA sequence in human and murine cells. Genetic ablation of RB proteins in murine cells destabilized interactions within the NuRD macromolecular complex and mediated nuclear rearrangement of Mi2-β, an ATP-dependent helicase subunit with nucleosome remodeling activity. Depletion of Mi2-β, RbAP46 and HDAC2 reduced the repressor activity of the NuRD complex and reactivated a synthetic L1 reporter in human cells. Epigenetic reactivation of L1 in RB-null cells by DNA damage was markedly enhanced compared to wild type cells. Conclusions: RB proteins stabilize interactions of the NuRD corepressor complex within the L1 promoter to effect L1 silencing. L1 retroelements may serve as a scaffold on which RB builds heterochromatic regions that regulate chromatin function.

Original languageEnglish (US)
Article number38
JournalBMC Cancer
Volume16
Issue number1
DOIs
StatePublished - Jan 25 2016

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Multiprotein Complexes
Retinoblastoma Protein
Retroelements
Retinoblastoma
Co-Repressor Proteins
Epigenomics
Long Interspersed Nucleotide Elements
Macromolecular Substances
Null Lymphocytes
Nucleosomes
Chromatin Immunoprecipitation
Nucleic Acid Regulatory Sequences
RNA Interference
Cell Communication
DNA Damage
Chromatin
Adenosine Triphosphate
Technology

Keywords

  • Chromatin
  • Gene silencing
  • Long interspersed nuclear element-1
  • Nucleosomal and remodeling deacetylase complex
  • Retinoblastoma proteins

ASJC Scopus subject areas

  • Oncology
  • Cancer Research
  • Genetics

Cite this

LINE-1 silencing by retinoblastoma proteins is effected through the nucleosomal and remodeling deacetylase multiprotein complex. / Montoya-Durango, Diego E.; Ramos, Kenneth A.; Bojang, Pasano; Ruiz, Lorell; Ramos, Irma; Ramos, Kenneth.

In: BMC Cancer, Vol. 16, No. 1, 38, 25.01.2016.

Research output: Contribution to journalArticle

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AB - Background: Long Interspersed Nuclear Element-1 (L1) is an oncogenic mammalian retroelement silenced early in development via tightly controlled epigenetic mechanisms. We have previously shown that the regulatory region of human and murine L1s interact with retinoblastoma (RB) proteins to effect retroelement silencing. The present studies were conducted to identify the corepressor complex responsible for RB-mediated silencing of L1. Methods: Chromatin immunoprecipitation and silencing RNA technology were used to identify the repressor complex that silences L1 in human and murine cells. Results: Components of the Nucleosomal and Remodeling Deacetylase (NuRD) multiprotein complex specifically enriched the L1 5'-untranslated DNA sequence in human and murine cells. Genetic ablation of RB proteins in murine cells destabilized interactions within the NuRD macromolecular complex and mediated nuclear rearrangement of Mi2-β, an ATP-dependent helicase subunit with nucleosome remodeling activity. Depletion of Mi2-β, RbAP46 and HDAC2 reduced the repressor activity of the NuRD complex and reactivated a synthetic L1 reporter in human cells. Epigenetic reactivation of L1 in RB-null cells by DNA damage was markedly enhanced compared to wild type cells. Conclusions: RB proteins stabilize interactions of the NuRD corepressor complex within the L1 promoter to effect L1 silencing. L1 retroelements may serve as a scaffold on which RB builds heterochromatic regions that regulate chromatin function.

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