title: A conserved pathway to activate BRCA1-dependent ubiquitylation at DNA damage sites.
abstract: The BRCA1 tumour suppressor and its heterodimeric partner BARD1 constitute an E3-ubiquitin (Ub) ligase and function in DNA repair by unknown mechanisms. We show here that the Caenorhabditis elegans BRCA1/BARD1 (CeBCD) complex possesses an E3-Ub ligase responsible for ubiquitylation at DNA damage sites following ionizing radiation (IR). The DNA damage checkpoint promotes the association of the CeBCD complex with E2-Ub conjugating enzyme, Ubc5(LET-70), leading to the formation of an active E3-Ub ligase on chromatin following IR. Correspondingly, defects in Ubc5(let-70) or the DNA damage checkpoint genes atl-1 or mre-11 abolish CeBCD-dependent ubiquitylation in vivo. Extending these findings to human cells reveals a requirement for UbcH5c, the MRN complex, gamma-H2AX and a co-dependence for ATM and ATR kinases for BRCA1-dependent ubiquitylation at DNA damage sites. Furthermore, we demonstrate that the DNA damage checkpoint promotes the association between BRCA1 and UbcH5c to form an active E3-Ub ligase on chromatin after IR. These data reveal that BRCA1-dependent ubiquitylation is activated at sites of DNA repair by the checkpoint as part of a conserved DNA damage response.
authors.affiliation: DNA Damage Response Laboratory, Cancer Research UK, London Research Institute, Clare Hall Laboratories, South Mimms, UK.
authors.forename: Jolanta
authors.initials: J
authors.lastname: Polanowska
authors.forename: Julie S
authors.initials: JS
authors.lastname: Martin
authors.forename: Tatiana
authors.initials: T
authors.lastname: Garcia-Muse
authors.forename: Mark I R
authors.initials: MI
authors.lastname: Petalcorin
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Boulton
mesh_terms: D000818:Animals; D019313:BRCA1 Protein / Q000235:genetics / Q000378:metabolism*; D017173:Caenorhabditis elegans / Q000235:genetics / Q000378:metabolism; D029742:Caenorhabditis elegans Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002843:Chromatin / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D004789:Enzyme Activation; D006801:Humans; D046912:Multiprotein Complexes; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051135:Rad51 Recombinase / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism
chemical_list: D019313:BRCA1 Protein; D029742:Caenorhabditis elegans Proteins; D002843:Chromatin; D046912:Multiprotein Complexes; D034741:RNA, Small Interfering; D025801:Ubiquitin; D044767:Ubiquitin-Protein Ligases; D051135:Rad51 Recombinase