The histone variant macroH2A1 is a BRCA1 ubiquitin ligase substrate
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Q Exactive
ORGANISM(S): Homo Sapiens (ncbitaxon:9606)
SUBMITTER: 
Jun Qin
PROVIDER: MSV000081054 | MassIVE | Sun Apr 30 17:31:00 BST 2017
SECONDARY ACCESSION(S): PXD006411
REPOSITORIES: MassIVE
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Project description:BRCA1/BARD1 is a macroH2A1-specific E3 ligase and implicates a role for macroH2A1 K123 ubiquitination in cellular senescence
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Project description:Although PARP inhibitors (PARPi) now form part of the standard-of-care for the treatment of homologous recombination defective cancers, de novo and acquired resistance limits their overall effectiveness. Previously, overexpression of the BRCA1-∆11q splice variant has been shown to cause PARPi resistance. How cancer cells achieve increased BRCA1-∆11q expression has remained unclear. Using isogenic cells with different BRCA1 mutations, we show that reduction in HUWE1 leads to increased levels of BRCA1-∆11q and PARPi resistance. This effect is specific to cells able to express BRCA1-∆11q (e.g. BRCA1 exon 11 mutant cells) and is not seen in BRCA1 mutants that cannot express BRCA1-∆11q, nor in BRCA2 mutant cells. As well as increasing levels of BRCA1-∆11q protein in exon 11 mutant cells, HUWE1 silencing also restores RAD51 nuclear foci and platinum salt resistance. HUWE1 catalytic domain mutations were also seen in a case of PARPi resistant, BRCA1 exon 11 mutant, high grade serous ovarian cancer. These results suggest how elevated levels of BRCA1-∆11q and PARPi resistance can be achieved, identify HUWE1 as a candidate biomarker of PARPi resistance for assessment in future clinical trials and illustrate how some PARPi resistance mechanisms may only operate in patients with particular BRCA1 mutations.
2023-07-18 | PXD040430 | Pride
Project description:The functional consequences of missense variants in disease genes are difficult to predict. We assessed if gene expression profiles could distinguish between BRCA1 or BRCA2 pathogenic truncating and missense mutation carriers and familial breast cancer cases whose disease was not attributable to BRCA1 or BRCA2 mutations (BRCAX cases). 72 cell lines from affected women in high-risk breast-ovarian families were assayed after exposure to ionising irradiation, including 23 BRCA1 carriers, 22 BRCA2 carriers, and 27 BRCAX individuals. A subset of 10 BRCAX individuals carried rare BRCA1/2 sequence variants considered to be of low clinical significance (LCS). BRCA1 and BRCA2 mutation carriers had similar expression profiles, with some subclustering of missense mutation carriers. The majority of BRCAX individuals formed a distinct cluster, but BRCAX individuals with LCS variants had expression profiles similar to BRCA1/2 mutation carriers. Gaussian Process Classifier predicted BRCA1, BRCA2 and BRCAX status with a maximum of 62% accuracy, and prediction accuracy decreased with inclusion of BRCAX samples carrying an LCS variant, and inclusion of pathogenic missense carriers. Similarly, prediction of mutation status with gene lists derived using Support Vector Machines was good for BRCAX samples without an LCS variant (82-94%), poor for BRCAX with an LCS (40-50%), and improved for pathogenic BRCA1/2 mutation carriers when the gene list used for prediction was appropriate to mutation effect being tested (71-100%). This study indicates that mutation effect, and presence of rare variants possibly associated with a low risk of cancer, must be considered in the development of array-based assays of variant pathogenicity. Keywords: cell type comparison, stress response
2008-03-21 | GSE10905 | GEO
Project description:It has been recognized that BRCA1, in the form of the BRCA1/BARD1 heterodimer, acting as an ubiquitin E3 ligase offered a possible mechanism to explain its pleiotrophic nature of BRCA1 activity. Our observation that mice lacking BRCA1 enzymatic activity are viable apart from male sterility was unexpected. Our results suggest that the E3 ligase activity of BRCA1 is largely dispensable for normal development and is not essential for all BRCA1 functions. Thus, many of the known and unknown functions of BRCA1 are likely to be mediated independent of its ability to catalyze ubiquitination. The genome copy number patterns were studied on the mice tumors that lacks E3 ubiqitin ligase activity of BRCA1 and were compared to copy number profile of mice lacking p53 and both brca1 and p53. Array CGH was performed using Agilent mouse CGH microarray 244K kit. Genomic DNA isolated from tumor tissue and its corresponding mouse tail were labelled with two different dyes and hybridized simultaneously on to microarray slides to perform comparitive genomic hybridization.
2011-08-25 | E-GEOD-31673 | biostudies-arrayexpress
Project description:It has been recognized that BRCA1, in the form of the BRCA1/BARD1 heterodimer, acting as an ubiquitin E3 ligase offered a possible mechanism to explain its pleiotrophic nature of BRCA1 activity. Our observation that mice lacking BRCA1 enzymatic activity are viable apart from male sterility was unexpected. Our results suggest that the E3 ligase activity of BRCA1 is largely dispensable for normal development and is not essential for all BRCA1 functions. Thus, many of the known and unknown functions of BRCA1 are likely to be mediated independent of its ability to catalyze ubiquitination. The genome copy number patterns were studied on the mice tumors that lacks E3 ubiqitin ligase activity of BRCA1 and were compared to copy number profile of mice lacking p53 and both brca1 and p53.
2011-08-26 | GSE31673 | GEO
Project description: Not available
| S-EPMC8763022 | biostudies-literature
Project description:BRCA1, a well-known breast and ovarian cancer susceptibility gene with multiple interacting partners, is predicted to have diverse biological functions. However, to date its only well-established role is in the repair of damaged DNA and cell cycle regulation. In this regard, the etiopathological study of low penetrant variants of BRCA1 provides an opportunity to uncover its other physiologically important functions. Using this rationale, we studied the R1699Q variant of BRCA1, a potentially moderate risk variant, and found that it does not impair DNA damage repair but abrogates the repression of miR-155, a bona fide oncomir. We further show that in the absence of functional BRCA1, miR-155 is up-regulated in BRCA1-deficient mouse mammary epithelial cells, human and mouse BRCA1-deficienct breast tumor cell lines as well as tumors. Mechanistically, we found that BRCA1 represses miR-155 expression via its association with HDAC2, which deacetylates H2A and H3 on the miR-155 promoter. Finally, we show that over-expression of miR-155 accelerates whereas the knockdown of miR-155 attenuates the growth of tumor cell lines in vivo. Taken together, our findings demonstrate a new mode of tumor suppression by BRCA1 and reveal miR-155 as a potential therapeutic target for BRCA1-deficient tumors. This SuperSeries is composed of the following subset Series: GSE31611: Expression data from embryoid body with BRCA1 mutation [mRNA] GSE31636: Expression data from embryoid body with BRCA1 mutation [miRNA] Refer to individual Series
2011-12-31 | E-GEOD-31637 | biostudies-arrayexpress