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BRCA1-associated RING domain protein 1 (EC (BARD-1) (RING-type E3 ubiquitin transferase BARD1)


BRCA1 and BARD1 mediate apoptotic resistance but not longevity upon mitochondrial stress in [i]Caenorhabditis elegans[/i].

Interventions that promote healthy aging are typically associated with increased stress resistance. Paradoxically, reducing the activity of core biological processes such as mitochondrial or insulin metabolism promotes the expression of adaptive responses, which in turn increase animal longevity and resistance to stress. In this study, we investigated the relation between the extended [i]Caenorhabditis elegans[/i] lifespan elicited by reduction in mitochondrial functionality and resistance to genotoxic stress. We find that reducing mitochondrial activity during development confers germline resistance to DNA damage-induced cell cycle arrest and apoptosis in a cell-non-autonomous manner. We identified the [i]C. elegans[/i] homologs of the BRCA1/BARD1 tumor suppressor genes, [i]brc-1/brd-1[/i], as mediators of the anti-apoptotic effect but dispensable for lifespan extension upon mitochondrial stress. Unexpectedly, while reduced mitochondrial activity only in the soma was not sufficient to promote longevity, its reduction only in the germline or in germline-less strains still prolonged lifespan. Thus, in animals with partial reduction in mitochondrial functionality, the mechanisms activated during development to safeguard the germline against genotoxic stress are uncoupled from those required for somatic robustness and animal longevity.

MeSH Terms

  • Animals
  • Apoptosis
  • Caenorhabditis elegans
  • Caenorhabditis elegans Proteins
  • Cell Proliferation
  • DNA Damage
  • DNA Repair
  • Germ Cells
  • Longevity
  • Mitochondria
  • Mitosis
  • Stress, Physiological
  • Tumor Suppressor Proteins
  • Ubiquitin-Protein Ligases


  • BRC‐1/BRD‐1
  • DNA damage
  • aging
  • apoptosis
  • mitochondria

The Histone Variant MacroH2A1 Is a BRCA1 Ubiquitin Ligase Substrate.

The breast- and ovarian-cancer-specific tumor suppressor BRCA1 and its heterodimeric partner BARD1 contain RING domains that implicate them as E3 ubiquitin ligases. Despite extensive efforts, the bona fide substrates of BRCA1/BARD1 remain elusive. Here, we used recombinant GST fused to four UBA domains to enrich ubiquitinated proteins followed by a Lys-ε-Gly-Gly (diGly) antibody to enrich ubiquitinated tryptic peptides. This tandem affinity purification method coupled with mass spectrometry identified 101 putative BRCA1/BARD1 E3 substrates. We identified the histone variant macroH2A1 from the screen and showed that BRCA1/BARD1 ubiquitinates macroH2A1 at lysine 123 in vitro and in vivo. Primary human fibroblasts stably expressing a ubiquitination-deficient macroH2A1 mutant were defective in cellular senescence compared to their wild-type counterpart. Our study demonstrates that BRCA1/BARD1 is a macroH2A1 E3 ligase and implicates a role for macroH2A1 K123 ubiquitination in cellular senescence.

MeSH Terms

  • Amino Acid Sequence
  • BRCA1 Protein
  • Cell Line
  • Cellular Senescence
  • Chromatography, Affinity
  • Histones
  • Humans
  • Lysine
  • Substrate Specificity
  • Ubiquitin
  • Ubiquitin-Protein Ligases
  • Ubiquitination


  • BRCA1
  • E3 ligase substrate
  • macroH2A1.1
  • senescence
  • ubiquitination