BARD1

BARD1
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1JM7, 2NTE, 2R1Z, 3C5R, 3FA2
Identifiers
Aliases	BARD1, BRCA1 associated RING domain 1
External IDs	OMIM: 601593 MGI: 1328361 HomoloGene: 400 GeneCards: BARD1
Gene location (Human) Chr. Chromosome 2 (human) Band 2q35 Start 214,725,646 bp End 214,809,683 bp
Gene location (Mouse) Chr. Chromosome 1 (mouse) Band 1|1 C3 Start 71,066,657 bp End 71,142,305 bp
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in secondary oocyte nipple Achilles tendon saphenous vein human penis bone marrow cancellous bone amniotic fluid cavity of mouth vena cava Top expressed in secondary oocyte urethra spermatocyte male urethra morula yolk sac spermatid thymus lip seminiferous tubule More reference expression data BioGPS More reference expression data
Gene ontology Molecular function metal ion binding protein homodimerization activity kinase binding RNA binding protein heterodimerization activity ubiquitin-protein transferase activity protein binding transferase activity Cellular component cytoplasm BRCA1-A complex BRCA1-BARD1 complex ubiquitin ligase complex nucleus nucleoplasm nuclear speck cytoplasmic ribonucleoprotein granule Biological process regulation of phosphorylation negative regulation of apoptotic process protein K6-linked ubiquitination negative regulation of mRNA 3'-end processing positive regulation of protein catabolic process negative regulation of protein export from nucleus double-strand break repair via nonhomologous end joining cellular response to DNA damage stimulus tissue homeostasis protein ubiquitination positive regulation of apoptotic process DNA replication DNA double-strand break processing DNA repair protein deubiquitination regulation of signal transduction by p53 class mediator Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 580 12021 Ensembl ENSG00000138376 ENSMUSG00000026196 UniProt Q99728 O70445 RefSeq (mRNA) NM_000465 NM_001282543 NM_001282545 NM_001282548 NM_001282549 NM_007525 RefSeq (protein) NP_000456 NP_001269472 NP_001269474 NP_001269477 NP_001269478 NP_001269474.1 NP_031551 Location (UCSC) Chr 2: 214.73 – 214.81 Mb Chr 1: 71.07 – 71.14 Mb PubMed search
Wikidata
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BRCA1-associated RING domain protein 1 is a protein that in humans is encoded by the BARD1 gene. The human BARD1 protein is 777 amino acids long and contains a RING finger domain (residues 46-90), four ankyrin repeats (residues 420-555), and two tandem BRCT domains (residues 568-777).

Function

Most, if not all, BRCA1 heterodimerizes with BARD1 in vivo. BARD1 and BRCA1 form a heterodimer via their N-terminal RING finger domains. The BARD1-BRCA1 interaction is observed in vivo and in vitro and is essential for BRCA1 stability. BARD1 shares homology with the two most conserved regions of BRCA1: the N-terminal RING motif and the C-terminal BRCT domain. The RING motif is a cysteine-rich sequence found in a variety of proteins that regulate cell growth, including the products of tumor suppressor genes and dominant protooncogenes, and developmentally important genes such as the polycomb group of genes. The BARD1 protein also contains three tandem ankyrin repeats.

The BARD1/BRCA1 interaction is disrupted by tumorigenic amino acid substitutions in BRCA1, implying that the formation of a stable complex between these proteins may be an essential aspect of BRCA1 tumor suppression. BARD1 may be the target of oncogenic mutations in breast or ovarian cancer. Mutations in the BARD1 protein that affect its structure appear in many breast, ovarian, and uterine cancers, suggesting the mutations disable BARD1's tumor suppressor function. Three missense mutations, each affecting BARD1's BRCT domain, are known to be implicated in cancers: C645R is associated with breast and ovarian cancers, V695L is associated with breast cancer, and S761N is associated with breast and uterine cancers. BARD1 expression is upregulated by genotoxic stress and involved in apoptosis through binding and stabilizing p53 independently of BRCA1.

BARD1 is vital in the rapid relocation of BRCA1 to DNA damage sites. BARD1 tandem BRCA1 C-terminus (BRCT) motifs fold into a binding pocket with a key lysine residue (K619), and bind to poly(ADP-ribose) (PAR), which targets the BRCA1/BARD1 heterodimer to damaged DNA sites. Double stranded breaks (DSB) in DNA trigger poly(ADPribose) polymerase 1 (PARP1) to catalyze the formation of poly(ADPribose) (PAR) so that PAR can then bind to an array of DNA response proteins, including the BRCA1/BARD1 heterodimer, and target them to DNA damage sites. When the BRCA1/BARD1 heterodimer is transported to the damaged DNA site, it acts as an E3 ubiquitin ligase. The BRCA1/BARD1 heterodimer ubiquitinates RNA polymerase II, preventing the transcription of the damaged DNA, and restoring genetic stability.

DNA repair

BRCA1-BARD1 appears to have an important function in the recruitment of RAD51 protein to DNA double-strand breaks which is a crucial early step in the homologous recombinational repair of these breaks. It is likely that BRCA1-BARD1 functions as part of a higher-order “homologous recombination mediator complex” along with two other tumor suppressor proteins BRCA2 and PALB2.

Interactions

BARD1 has been shown to interact with:

Implication in Cancer Treatments

If a cancer cell's capacity to repair DNA damage were incapacitated, cancer treatments would be more effective. Inhibiting cancer cells' BRCA1/BARD1 heterodimer from relocating to DNA damage sites would induce tumor cell death rather than repair. One inhibition possibility is the BARD1 BRCT key lysine residue (K619). Inhibiting this lysine residue's ability to bind poly(ADP-ribose) would prevent the BRCA1/BARD1 heterodimer from localizing to DNA damage sites and subsequently prevent DNA damage repair. This would make cancer therapies such as chemotherapy and radiation vastly more effective.

External links

• Human BARD1 genome location and BARD1 gene details page in the UCSC Genome Browser.
• Overview of all the structural information available in the PDB for UniProt: Q99728 (BRCA1-associated RING domain protein 1) at the PDBe-KB.

Further reading