1
|
Li J, Zheng H, Hou J, Chen J, Zhang F, Yang X, Jin F, Xi Y. X-linked RBBP7 mutation causes maturation arrest and testicular tumors. J Clin Invest 2023; 133:e171541. [PMID: 37843278 PMCID: PMC10575721 DOI: 10.1172/jci171541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 08/24/2023] [Indexed: 10/17/2023] Open
Abstract
Maturation arrest (MA) is a subtype of non-obstructive azoospermia, and male infertility is a known risk factor for testicular tumors. However, the genetic basis for many affected individuals remains unknown. Here, we identified a deleterious hemizygous variant of X-linked retinoblastoma-binding protein 7 (RBBP7) as a potential key cause of MA, which was also found to be associated with the development of Leydig cell tumors. This mutation resulted in premature protein translation termination, affecting the sixth WD40 domain of the RBBP7 and the interaction of the mutated RBBP7 with histone H4. Decreased BRCA1 and increased γH2AX were observed in the proband. In mouse spermatogonial and pachytene spermatocyte-derived cells, deprivation of rbbp7 led to cell cycle arrest and apoptosis. In Drosophila, knockdown of RBBP7/Caf1-55 in germ cells resulted in complete absence of germ cells and reduced testis size, whereas knockdown of RBBP7/Caf1-55 in cyst cells resulted in hyperproliferative testicular cells. Interestingly, male infertility caused by Caf1-55 deficiency was rescued by ectopic expression of wild-type human RBBP7 but not mutant variants, suggesting the importance of RBBP7 in spermatogenesis. Our study provides insights into the mechanisms underlying the co-occurrence of MA and testicular tumors and may pave the way for innovative genetic diagnostics of these 2 diseases.
Collapse
Affiliation(s)
- Jingping Li
- Department of Reproductive Endocrinology and
| | - Huimei Zheng
- Division of Human Reproduction and Developmental Genetics, Reproductive Medicine Center, Women’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Jiaru Hou
- Division of Human Reproduction and Developmental Genetics, Reproductive Medicine Center, Women’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Developmental Disorders, Zhejiang University School of Medicine, Hangzhou, China
| | - Jianhua Chen
- Department of Pathology, Reproductive Medicine Center, Women’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | | | - Xiaohang Yang
- Division of Human Reproduction and Developmental Genetics, Reproductive Medicine Center, Women’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Developmental Disorders, Zhejiang University School of Medicine, Hangzhou, China
| | - Fan Jin
- Department of Reproductive Endocrinology and
| | - Yongmei Xi
- Division of Human Reproduction and Developmental Genetics, Reproductive Medicine Center, Women’s Hospital, Zhejiang University School of Medicine, Hangzhou, China
- Institute of Genetics, Zhejiang Provincial Key Laboratory of Genetic & Developmental Disorders, Zhejiang University School of Medicine, Hangzhou, China
| |
Collapse
|
2
|
Hypoxia-induced RBBP7 promotes esophagus cancer progression by inducing CDK4 expression. Acta Biochim Biophys Sin (Shanghai) 2022; 54:179-186. [PMID: 35538026 PMCID: PMC9909297 DOI: 10.3724/abbs.2021027] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Hypoxia-induced epigenetic regulation calls for more effective therapeutic targets for esophageal cancer. We used GEPIA and UALCAN databases to screen survival-related and cancer stage-associated genes. Eca109 and KYSE450 esophageal cancer cell lines were cultured under normoxia, hypoxia, or CoCl-induced hypoxia conditions, which were further transfected with plasmids expressing RB binding protein 7 (RBBP7), hypoxia-inducible factor 1 (HIF1)-α, or RBBP7 shRNA. Colony formation and MTT assays were used to detect cell proliferation. Tumor sphere formation and stemness marker detection were applied to assess cell stemness. RT-PCR and western blot analysis were used to detect the relative mRNA level and protein expression, respectively. Luciferase assay was utilized to detect the direct interaction between HIF1α and RBBP7. Up-regulated RBBP7 was identified as one of the most prominent survival-related genes, which is negatively correlated with the overall survival (OS), disease recurrence-free survival (DFS), and tumor stages. Hypoxia-induced HIF1α up-regulates RBBP7 expression, which promotes esophagus cancer cell viability, proliferation, and stemness with increased cyclin-dependent kinase 4 (CDK4) expression. Luciferase reporter assay verified that HIF1α transcriptionally regulates the expression of RBBP7. We conclude that hypoxia induces high expression of RBBP7 which is at least partially mediated by HIF1α, up-regulates the expression of downstream CDK4, and thereby promotes tumor progression in esophageal cancer cells.
Collapse
|
3
|
Russi M, Marson D, Fermeglia A, Aulic S, Fermeglia M, Laurini E, Pricl S. The fellowship of the RING: BRCA1, its partner BARD1 and their liaison in DNA repair and cancer. Pharmacol Ther 2021; 232:108009. [PMID: 34619284 DOI: 10.1016/j.pharmthera.2021.108009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2021] [Revised: 08/22/2021] [Accepted: 09/20/2021] [Indexed: 12/12/2022]
Abstract
The breast cancer type 1 susceptibility protein (BRCA1) and its partner - the BRCA1-associated RING domain protein 1 (BARD1) - are key players in a plethora of fundamental biological functions including, among others, DNA repair, replication fork protection, cell cycle progression, telomere maintenance, chromatin remodeling, apoptosis and tumor suppression. However, mutations in their encoding genes transform them into dangerous threats, and substantially increase the risk of developing cancer and other malignancies during the lifetime of the affected individuals. Understanding how BRCA1 and BARD1 perform their biological activities therefore not only provides a powerful mean to prevent such fatal occurrences but can also pave the way to the development of new targeted therapeutics. Thus, through this review work we aim at presenting the major efforts focused on the functional characterization and structural insights of BRCA1 and BARD1, per se and in combination with all their principal mediators and regulators, and on the multifaceted roles these proteins play in the maintenance of human genome integrity.
Collapse
Affiliation(s)
- Maria Russi
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Domenico Marson
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Alice Fermeglia
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Suzana Aulic
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Maurizio Fermeglia
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Erik Laurini
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy
| | - Sabrina Pricl
- Molecular Biology and Nanotechnology Laboratory (MolBNL@UniTs), DEA, University of Trieste, Trieste, Italy; Department of General Biophysics, Faculty of Biology and Environmental Protection, University of Lodz, Lodz, Poland.
| |
Collapse
|
4
|
Yu N, Zhang P, Wang L, He X, Yang S, Lu H. RBBP7 is a prognostic biomarker in patients with esophageal squamous cell carcinoma. Oncol Lett 2018; 16:7204-7211. [PMID: 30546458 PMCID: PMC6256704 DOI: 10.3892/ol.2018.9543] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Accepted: 09/20/2018] [Indexed: 12/18/2022] Open
Abstract
Retinoblastoma-binding protein 7 (RBBP7) is an important component of several complexes that regulate chromatin metabolism. It is overexpressed in certain cancer types and serves conflicting roles in tumor progression. In the present study, the expression and roles of RBBP7 were explored in esophageal squamous cell carcinoma (ESCC). Immunohistochemical staining was used to detect RBBP7 expression in ESCC tissues. The mRNA sequencing profiles from the Cancer Genome Atlas and Genotype-Tissue Expression databases were mined to analyze the mRNA expression of RBBP7 in tissues. Proliferation, clone formation, apoptosis and Transwell invasion/migration assays were performed to explore the roles of RBBP7 in ESCC. RBBP7 was highly expressed in ESCC tissues. The protein and mRNA expression levels of RBBP7 were significantly elevated in tumor tissues compared with paired adjacent normal tissues. RBBP7 overexpression was associated with a poor overall survival in patients with ESCC. Furthermore, higher RBBP7 expression was significantly correlated with poor tumor differentiation, advanced regional lymph node involvement, and pathological TNM staging. Knockdown of RBBP7 in ESCC cells did not affect tumor apoptosis or tumor growth. However, the overexpression of RBBP7 significantly enhanced the invasion and migration of ESCC cells, whereas the knockdown of RBBP7 resulted in significantly decreased invasion and migration. The present study indicated that RBBP7 is a novel biomarker and prognosticator for patients with ESCC. Furthermore, RBBP7 serves crucial roles in promoting ESCC invasion and migration.
Collapse
Affiliation(s)
- Ning Yu
- Department of Ultrasonography, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - Peng Zhang
- Department of Gastroenterology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - Li Wang
- Department of Nursing, The Affiliated Qingdao Hiser Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - Xinjia He
- Department of Oncology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - Shanshan Yang
- Department of Oncology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| | - Haijun Lu
- Department of Oncology, The Affiliated Hospital of Qingdao University, Qingdao, Shandong 266000, P.R. China
| |
Collapse
|
5
|
Liu F, Cao L, Zhang T, Chang F, Xu Y, Li Q, Deng J, Li L, Shao G. CRL4B RBBP7 targets HUWE1 for ubiquitination and proteasomal degradation. Biochem Biophys Res Commun 2018; 501:440-447. [PMID: 29738775 DOI: 10.1016/j.bbrc.2018.05.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Accepted: 05/02/2018] [Indexed: 10/16/2022]
Abstract
The E3 ubiquitin ligase HUWE1/Mule/ARF-BP1 plays an important role in diverse biological processes including DNA damage repair and apoptosis. Our previous study has shown that in response to DNA damage HUWE1 was downregulated in CUL4B-mediated ubiquitination and subsequent proteasomal degradation, and CUL4B-mediated regulation of HUWE1 was important for cell survival upon DNA damage. CUL4B is a core component of the CUL4B Ring ligase complexes containing ROC1, DDB1 and a DDB1-Cullin Associated Factors (DCAFs), the latter of which are DDB1-binding WD40 adaptors critical for substrate recognition and recruitment. However, the identity of DCAF in CRL4B that mediates degradation of HUWE1 remains elusive. Here we report that RBBP7 is the DCAF in the CRL4B complex bridging the DDB1-CUL4B-ROC1 to HUWE1. Loading of HUWE1 to the E3 ubiquitin ligase complex resulted in its polyubiquitination, and consequently its proteasome mediated degradation. Overexpression of RBBP7 promoted HUWE1 protein degradation, while depletion of RBBP7 stabilized HUWE1, and hence accelerated the degradation of MCL-1 and BRCA1, two substrates of HUWE1 that are critical in apoptosis and DNA damage repair. Taken together, these data reveal CRL4BRBBP7 is the E3 ligase responsible for the proteasomal degradation of HUWE1, and further provide a potential strategy for cancer therapy by targeting HUWE1 and the CUL4B E3 ligase complex.
Collapse
Affiliation(s)
- Fei Liu
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China; Department of Pathology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Li Cao
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Ting Zhang
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Fen Chang
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Yongjie Xu
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Qin Li
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Jingcheng Deng
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Li Li
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China
| | - Genze Shao
- Department of Cell Biology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing, 100191, China.
| |
Collapse
|
6
|
Sharma B, Preet Kaur R, Raut S, Munshi A. BRCA1 mutation spectrum, functions, and therapeutic strategies: The story so far. Curr Probl Cancer 2018; 42:189-207. [PMID: 29452958 DOI: 10.1016/j.currproblcancer.2018.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2017] [Revised: 12/19/2017] [Accepted: 01/04/2018] [Indexed: 02/07/2023]
Abstract
BRCA1 gene mutations account for about 25-28% of hereditary Breast Cancer as BRCA1 is included in the category of high penetrance genes. Except for few commonmutations, there is a heterogenous spectrum of BRCA1 mutations in various ethnic groups. 185AGdel and 5382ins Care the most common BRCA1 alterations (founder mutations) which have been identified in most of the population. This review has been compiled with an aim to consolidate the information on genetic variants reported in BRCA1 found in various ethnic groups, their functional implications if known; involvement of BRCA1 in various cellular pathways/processes and potential BRCA1 targeted therapies. The pathological variations of BRCA1 vary among different ethical groups. A systematic search in PubMed and Google scholar for the literature on BRCA1 gene was carried out to figure out structure and function of BRCA1 gene. BRCA1 is a large protein having 1863 amino acids with multiple functional domains and interacts with multiple proteins to carry out various crucial cellular processes. BRCA1 plays a major role in maintaining genome integrity, transcription regulation, chromatin remodeling, cell cycle checkpoint control, DNA damage repair, chromosomal segregation, and apoptosis. Studies investigating the phenotypic response of mutant BRCA1 protein and comparing it to wildtype BRCA1 protein are clinically important as they are involved in homologous recombination and other repair mechanisms. These studies may help in developing more targetted therapies, detecting novel interacting partners, identification of new signaling pathways that BRCA1 is a part of or downstream target genes that BRCA1 affects.
Collapse
Affiliation(s)
- Babita Sharma
- Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, Punjab, India
| | - Raman Preet Kaur
- Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, Punjab, India
| | - Sonali Raut
- Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, Punjab, India
| | - Anjana Munshi
- Department of Human Genetics and Molecular Medicine, Central University of Punjab, Bathinda, Punjab, India.
| |
Collapse
|
7
|
Assembly of a comprehensive regulatory network for the mammalian circadian clock: a bioinformatics approach. PLoS One 2015; 10:e0126283. [PMID: 25945798 PMCID: PMC4422523 DOI: 10.1371/journal.pone.0126283] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 03/31/2015] [Indexed: 12/12/2022] Open
Abstract
By regulating the timing of cellular processes, the circadian clock provides a way to adapt physiology and behaviour to the geophysical time. In mammals, a light-entrainable master clock located in the suprachiasmatic nucleus (SCN) controls peripheral clocks that are present in virtually every body cell. Defective circadian timing is associated with several pathologies such as cancer and metabolic and sleep disorders. To better understand the circadian regulation of cellular processes, we developed a bioinformatics pipeline encompassing the analysis of high-throughput data sets and the exploitation of published knowledge by text-mining. We identified 118 novel potential clock-regulated genes and integrated them into an existing high-quality circadian network, generating the to-date most comprehensive network of circadian regulated genes (NCRG). To validate particular elements in our network, we assessed publicly available ChIP-seq data for BMAL1, REV-ERBα/β and RORα/γ proteins and found strong evidence for circadian regulation of Elavl1, Nme1, Dhx6, Med1 and Rbbp7 all of which are involved in the regulation of tumourigenesis. Furthermore, we identified Ncl and Ddx6, as targets of RORγ and REV-ERBα, β, respectively. Most interestingly, these genes were also reported to be involved in miRNA regulation; in particular, NCL regulates several miRNAs, all involved in cancer aggressiveness. Thus, NCL represents a novel potential link via which the circadian clock, and specifically RORγ, regulates the expression of miRNAs, with particular consequences in breast cancer progression. Our findings bring us one step forward towards a mechanistic understanding of mammalian circadian regulation, and provide further evidence of the influence of circadian deregulation in cancer.
Collapse
|
8
|
Pickholtz I, Saadyan S, Keshet GI, Wang VS, Cohen R, Bouwman P, Jonkers J, Byers SW, Papa MZ, Yarden RI. Cooperation between BRCA1 and vitamin D is critical for histone acetylation of the p21waf1 promoter and growth inhibition of breast cancer cells and cancer stem-like cells. Oncotarget 2014; 5:11827-46. [PMID: 25460500 PMCID: PMC4322975 DOI: 10.18632/oncotarget.2582] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 10/09/2014] [Indexed: 12/19/2022] Open
Abstract
Carriers of germline mutations in the BRCA1 gene have a significant increased lifetime risk for being diagnosed with breast cancer. The incomplete penetrance of BRCA1 suggests that environmental and/or genetic factors modify the risk and incidence among mutation carriers. Nutrition and particular micronutrients play a central role in modifying the phenotypic expression of a given genotype by regulating chromatin structure and gene expression. The active form of vitamin D, 1α,25-dihydroxyvitamin D3, is a potent inhibitor of breast cancer growth. Here we report that two non-calcemic analogues of 1α,25-dihydroxyvitamin D3, seocalcitol (EB1089) and QW-1624F2-2, collaborate with BRCA1 in mediating growth inhibition of breast cancer cells and breast cancer stem-like cells. EB1089 induces a G1/S phase growth arrest that coincides with induction of p21waf1 expression only in BRCA1-expressing cells. A complete knockdown of BRCA1 or p21waf1 renders the cells unresponsive to EB1089. Furthermore, we show that in the presence of ligand, BRCA1 associates with vitamin D receptor (VDR) and the complex co-occupies vitamin D responsive elements (VDRE) at the CDKN1A (p21waf1) promoter and enhances acetylation of histone H3 and H4 at these sites. Thus, BRCA1 expression is critical for mediating the biological impact of vitamin D3 in breast tumor cells.
Collapse
Affiliation(s)
- Itay Pickholtz
- Laboratory of Genomic Applications, Department of Surgical Oncology, Sheba Medical Center, Ramat-Gan 52621, Israel
- Sheba Cancer Research Center, Sheba Medical Center, Ramat-Gan 52621, Israel
- Sackler school of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Shira Saadyan
- Laboratory of Genomic Applications, Department of Surgical Oncology, Sheba Medical Center, Ramat-Gan 52621, Israel
| | - Gilmor I. Keshet
- Sheba Cancer Research Center, Sheba Medical Center, Ramat-Gan 52621, Israel
| | - Victor S. Wang
- Department of Human Science, Georgetown University Medical Center, Washington DC 20057, USA
| | - Rachel Cohen
- Laboratory of Genomic Applications, Department of Surgical Oncology, Sheba Medical Center, Ramat-Gan 52621, Israel
| | - Peter Bouwman
- Division of Molecular Pathology and Cancer Genomic Center, The Netherland Cancer Institute, Amsterdam 1066, The Netherlands
| | - Jos Jonkers
- Division of Molecular Pathology and Cancer Genomic Center, The Netherland Cancer Institute, Amsterdam 1066, The Netherlands
| | - Stephen W. Byers
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, NW Washington DC 20057, USA
| | - Moshe Z. Papa
- Laboratory of Genomic Applications, Department of Surgical Oncology, Sheba Medical Center, Ramat-Gan 52621, Israel
- Sackler school of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Ronit I. Yarden
- Laboratory of Genomic Applications, Department of Surgical Oncology, Sheba Medical Center, Ramat-Gan 52621, Israel
- Sheba Cancer Research Center, Sheba Medical Center, Ramat-Gan 52621, Israel
- Department of Human Science, Georgetown University Medical Center, Washington DC 20057, USA
- Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, NW Washington DC 20057, USA
| |
Collapse
|
9
|
Savage KI, Harkin DP. BRCA1, a 'complex' protein involved in the maintenance of genomic stability. FEBS J 2014; 282:630-46. [PMID: 25400280 DOI: 10.1111/febs.13150] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 11/10/2014] [Accepted: 11/13/2014] [Indexed: 12/15/2022]
Abstract
BRCA1 is a major breast and ovarian cancer susceptibility gene, with mutations in this gene predisposing women to a very high risk of developing breast and ovarian tumours. BRCA1 primarily functions to maintain genomic stability via critical roles in DNA repair, cell cycle checkpoint control, transcriptional regulation, apoptosis and mRNA splicing. As a result, BRCA1 mutations often result in defective DNA repair, genomic instability and sensitivity to DNA damaging agents. BRCA1 carries out these different functions through its ability to interact, and form complexes with, a vast array of proteins involved in multiple cellular processes, all of which are considered to contribute to its function as a tumour suppressor. This review discusses and highlights recent research into the functions of BRCA1-related protein complexes and their roles in maintaining genomic stability and tumour suppression.
Collapse
Affiliation(s)
- Kienan I Savage
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, UK
| | | |
Collapse
|
10
|
Yi YW, Kang HJ, Bae I. BRCA1 and Oxidative Stress. Cancers (Basel) 2014; 6:771-95. [PMID: 24704793 PMCID: PMC4074803 DOI: 10.3390/cancers6020771] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/20/2014] [Accepted: 03/24/2014] [Indexed: 01/07/2023] Open
Abstract
The breast cancer susceptibility gene 1 (BRCA1) has been well established as a tumor suppressor and functions primarily by maintaining genome integrity. Genome stability is compromised when cells are exposed to oxidative stress. Increasing evidence suggests that BRCA1 regulates oxidative stress and this may be another mechanism in preventing carcinogenesis in normal cells. Oxidative stress caused by reactive oxygen species (ROS) is implicated in carcinogenesis and is used strategically to treat human cancer. Thus, it is essential to understand the function of BRCA1 in oxidative stress regulation. In this review, we briefly summarize BRCA1's many binding partners and mechanisms, and discuss data supporting the function of BRCA1 in oxidative stress regulation. Finally, we consider its significance in prevention and/or treatment of BRCA1-related cancers.
Collapse
Affiliation(s)
- Yong Weon Yi
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA.
| | - Hyo Jin Kang
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA.
| | - Insoo Bae
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA.
| |
Collapse
|
11
|
Abstract
Cancer cells silence autosomal tumor suppressor genes by Knudson's two-hit mechanism in which loss-of-function mutations and then loss of heterozygosity occur at the tumor suppressor gene loci. However, the identification of X-linked tumor suppressor genes has challenged the traditional theory of 'two-hit inactivation' in tumor suppressor genes, introducing the novel concept that a single genetic hit can cause loss of tumor suppressor function. The mechanism through which these genes are silenced in human cancer is unclear, but elucidating the details will greatly enhance our understanding of the pathogenesis of human cancer. Here, we review the identification of X-linked tumor suppressor genes and discuss the potential mechanisms of their inactivation. In addition, we also discuss how the identification of X-linked tumor suppressor genes can potentially lead to new approaches in cancer therapy.
Collapse
Affiliation(s)
- Runhua Liu
- Division of Immunotherapy, Department of Surgery, University of Michigan School of Medicine, Ann Arbor, MI, USA
- Department of Genetics, School of Medicine, University of Alabama at Birmingham and Comprehensive Cancer Center, Birmingham, AL, USA
| | - Mandy Kain
- Division of Immunotherapy, Department of Surgery, University of Michigan School of Medicine, Ann Arbor, MI, USA
| | - Lizhong Wang
- Division of Immunotherapy, Department of Surgery, University of Michigan School of Medicine, Ann Arbor, MI, USA
- Department of Genetics, School of Medicine, University of Alabama at Birmingham and Comprehensive Cancer Center, Birmingham, AL, USA
| |
Collapse
|
12
|
Gorski JJ, Savage KI, Mulligan JM, McDade SS, Blayney JK, Ge Z, Harkin DP. Profiling of the BRCA1 transcriptome through microarray and ChIP-chip analysis. Nucleic Acids Res 2011; 39:9536-48. [PMID: 21880590 PMCID: PMC3239190 DOI: 10.1093/nar/gkr679] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 07/27/2011] [Accepted: 08/01/2011] [Indexed: 11/16/2022] Open
Abstract
A role for BRCA1 in the direct and indirect regulation of transcription is well established. However, a comprehensive view of the degree to which BRCA1 impacts transcriptional regulation on a genome-wide level has not been defined. We performed genome-wide expression profiling and ChIP-chip analysis, comparison of which revealed that although BRCA1 depletion results in transcriptional changes in 1294 genes, only 44 of these are promoter bound by BRCA1. However, 27% of these transcripts were linked to transcriptional regulation possibly explaining the large number of indirect transcriptional changes observed by microarray analysis. We show that no specific consensus sequence exists for BRCA1 DNA binding but rather demonstrate the presence of a number of known and novel transcription factor (TF)- binding sites commonly found on BRCA1 bound promoters. Co-immunoprecipitations confirmed that BRCA1 interacts with a number of these TFs including AP2-α, PAX2 and ZF5. Finally, we show that BRCA1 is bound to a subset of promoters of genes that are not altered by BRCA1 loss, but are transcriptionally regulated in a BRCA1-dependent manner upon DNA damage. These data suggest a model, whereby BRCA1 is present on defined promoters as part of an inactive complex poised to respond to various genotoxic stimuli.
Collapse
Affiliation(s)
- Julia J Gorski
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, Belfast BT9 7BL and ALMAC Diagnostics, Craigavon BT63 5QD, UK.
| | | | | | | | | | | | | |
Collapse
|
13
|
Abstract
BACKGROUND DBC1/KIAA1967 (deleted in breast cancer 1) is a putative tumour-suppressor gene cloned from a heterozygously deleted region in breast cancer specimens. Caspase-dependent processing of DBC1 promotes apoptosis, and depletion of endogenous DBC1 negatively regulates p53-dependent apoptosis through its specific inhibition of SIRT1. Hereditary breast and ovarian cancer susceptibility gene product BRCA1, by binding to the promoter region of SIRT1, is a positive regulator of SIRT1 expression. METHODS A physical interaction between DBC1 and BRCA1 was investigated both in vivo and in vitro. To determine the pathophysiological significance of DBC1, its role as a transcriptional factor was studied. RESULTS We found a physical interaction between the amino terminus of DBC1 and the carboxyl terminus of BRCA1, also known as the BRCT domain. Endogenous DBC1 and BRCA1 form a complex in the nucleus of intact cells, which is exported to the cytoplasm during ultraviolet-induced apoptosis. We also showed that the expression of DBC1 represses the transcriptional activation function of BRCT by a transient expression assay. The expression of DBC1 also inhibits the transactivation of the SIRT1 promoter mediated by full-length BRCA1. CONCLUSION These results revealed that DBC1 may modulate the cellular functions of BRCA1 and have important implications in the understanding of carcinogenesis in breast tissue.
Collapse
|
14
|
Analysis of the DNA binding activity of BRCA1 and its modulation by the tumour suppressor p53. PLoS One 2008; 3:e2336. [PMID: 18545657 PMCID: PMC2396507 DOI: 10.1371/journal.pone.0002336] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Accepted: 04/18/2008] [Indexed: 01/24/2023] Open
Abstract
Background The breast cancer susceptibility protein, BRCA1 functions to maintain the integrity of the genome. The exact mechanisms by which it does so, however, remain unclear. The ability of BRCA1 to bind directly to DNA suggests a more direct role. However, little research has been conducted to understand the functional relevance of this characteristic of BRCA1. In this study we examine the DNA substrate specificity of BRCA1 and how this may be controlled by one of its interacting partners, p53. Methodology/Principal Findings Using competition gel retardation assays we have examined the ability of residues 230-534 of BRCA1 to discriminate between different synthetic DNA substrates that mimic those recognised by the DNA damage response i.e. four-way junction DNA, mismatch containing DNA, bulge containing DNA and linear DNA. Of those tested the highest affinity observed was for four-way junction DNA, with a 20 fold excess of each of the other synthetic DNA's unable to compete for any of the bound BRCA1 230-534. We also observed a higher affinity for C∶C and bulge containing DNA compared to linear duplex and G∶T containing DNA. BRCA1 230-534 also has interaction sites for the tumour suppressor p53 and we show that titration of this complex into the DNA binding assays significantly reduces the affinity of BRCA1 for DNA. Conclusions/Significance In this paper we show that BRCA1 can discriminate between different types of DNA damage and we discuss the implications of this with respect to its function in DNA repair. We also show that the DNA binding activity can be inhibited by the tumour suppressor p53 and suggest that this may prevent genome destabilizing events such as HR between non-homologous sequences.
Collapse
|
15
|
Abstract
Emerging evidence indicates that the tumor microenvironmental stress of hypoxia can induce genetic instability in cancer cells. We and others have found that the expression levels of key genes within the DNA mismatch repair (MMR) and homologous recombination (HR) pathways are coordinately repressed by hypoxia. These decreases are associated with functional impairments in both MMR and HR repair under hypoxic conditions, and thus they represent a possible mechanistic explanation for the observed phenomenon of hypoxia-induced genetic instability. In parallel, studies also indicate that several DNA damage response factors are activated in response to hypoxia and subsequent reoxygenation, including ATM/ATR, Chkl/Chk2 and BRCA1. Taken together, these findings reveal that hypoxia induces a unique cellular stress response involving an initial, acute DNA damage response to hypoxia and reoxygenation, followed by a chronic response to prolonged hypoxia in which selected DNA repair pathways are coordinately suppressed. In this review, we discuss these pathways and the possible mechanisms involved, as well as the consequences for genetic instability and tumor progression within the tumor microenvironment.
Collapse
Affiliation(s)
- Ranjit S Bindra
- Department of Therapeutic Radiology, Yale University School of Medicine, New Haven, CT 06520-8040, USA
| | | | | |
Collapse
|
16
|
Karchin R, Monteiro ANA, Tavtigian SV, Carvalho MA, Sali A. Functional impact of missense variants in BRCA1 predicted by supervised learning. PLoS Comput Biol 2006; 3:e26. [PMID: 17305420 PMCID: PMC1797820 DOI: 10.1371/journal.pcbi.0030026] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2006] [Accepted: 12/27/2006] [Indexed: 11/19/2022] Open
Abstract
Many individuals tested for inherited cancer susceptibility at the BRCA1 gene locus are discovered to have variants of unknown clinical significance (UCVs). Most UCVs cause a single amino acid residue (missense) change in the BRCA1 protein. They can be biochemically assayed, but such evaluations are time-consuming and labor-intensive. Computational methods that classify and suggest explanations for UCV impact on protein function can complement functional tests. Here we describe a supervised learning approach to classification of BRCA1 UCVs. Using a novel combination of 16 predictive features, the algorithms were applied to retrospectively classify the impact of 36 BRCA1 C-terminal (BRCT) domain UCVs biochemically assayed to measure transactivation function and to blindly classify 54 documented UCVs. Majority vote of three supervised learning algorithms is in agreement with the assay for more than 94% of the UCVs. Two UCVs found deleterious by both the assay and the classifiers reveal a previously uncharacterized putative binding site. Clinicians may soon be able to use computational classifiers such as those described here to better inform patients. These classifiers can be adapted to other cancer susceptibility genes and systematically applied to prioritize the growing number of potential causative loci and variants found by large-scale disease association studies.
Collapse
Affiliation(s)
- Rachel Karchin
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
- Institute of Computational Medicine, Johns Hopkins University, Baltimore, Maryland, United States of America
- * To whom correspondence should be addressed. E-mail: (RK); (AS)
| | - Alvaro N. A Monteiro
- Risk Assessment, Detection, and Intervention Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | | | - Marcelo A Carvalho
- Risk Assessment, Detection, and Intervention Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Andrej Sali
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, California, United States of America
- California Institute for Quantitative Biomedical Research, University of California San Francisco, San Francisco, California, United States of America
- * To whom correspondence should be addressed. E-mail: (RK); (AS)
| |
Collapse
|
17
|
Mullan PB, Quinn JE, Harkin DP. The role of BRCA1 in transcriptional regulation and cell cycle control. Oncogene 2006; 25:5854-63. [PMID: 16998500 DOI: 10.1038/sj.onc.1209872] [Citation(s) in RCA: 223] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The exact functions of BRCA1 have not been fully described but it now seems apparent that it has roles in DNA damage repair, transcriptional regulation, cell cycle control and most recently in ubiquitylation. These functions of BRCA1 are most likely interdependent but this review will focus on the role of BRCA1 in relation to transcriptional regulation and in particular how this impacts upon cell cycle control. We will (i) describe the structure of BRCA1 and how it may contribute to its transcription function; (ii) describe the interaction of BRCA1 with the core transcriptional machinery (RNA polII); (iii) describe how BRCA1 may regulate transcription at an epigenetic level through chromatin modification; (iv) discuss the role of BRCA1 in modulating transcription through its association with sequence-specific transcription factors. Finally, we will discuss the possible effects of BRCA1 transcriptional regulation on downstream targets with known roles in cell cycle control.
Collapse
Affiliation(s)
- P B Mullan
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, Lisburn Road Belfast, Northern Ireland, UK
| | | | | |
Collapse
|
18
|
Hennig L, Bouveret R, Gruissem W. MSI1-like proteins: an escort service for chromatin assembly and remodeling complexes. Trends Cell Biol 2005; 15:295-302. [PMID: 15953547 DOI: 10.1016/j.tcb.2005.04.004] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 04/04/2005] [Accepted: 04/20/2005] [Indexed: 10/25/2022]
Abstract
MSI1-like WD40 repeat proteins are subunits of many protein complexes controlling chromatin dynamics. These proteins do not have any catalytic activity, but several recent studies using loss-of-function mutants established specific functions during development. Here, we review the current knowledge of MSI1-like proteins, including their phylogenetic history, expression patterns, biochemical interactions and mutant phenotypes. MSI1-like proteins, which are often targets or partners of tumor-suppressor proteins, are required during cell proliferation and differentiation in flies, nematodes and plants. We discuss the possibility that MSI1-like proteins could function to maintain epigenetic memory during development by targeting silencing complexes to chromatin during nucleosome assembly.
Collapse
Affiliation(s)
- Lars Hennig
- Institute of Plant Sciences, Swiss Federal Institute of Technology and Zürich-Basel Plant Science Center, ETH Center, CH-8092 Zürich.
| | | | | |
Collapse
|
19
|
Yao R, Lemon WJ, Wang Y, Grubbs CJ, Lubet RA, You M. Altered gene expression profile in mouse bladder cancers induced by hydroxybutyl(butyl)nitrosamine. Neoplasia 2005; 6:569-77. [PMID: 15548366 PMCID: PMC1531661 DOI: 10.1593/neo.04223] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
A variety of genetic alterations and gene expression changes are involved in the pathogenesis of bladder tumor. To explore these changes, oligonucleotide array analysis was performed on RNA obtained from carcinogen-induced mouse bladder tumors and normal mouse bladder epithelia using Affymetrix (Santa Clara, CA) MGU74Av2 GeneChips. Analysis yielded 1164 known genes that were changed in the tumors. Certain of the upregulated genes included EGFR-Ras signaling genes, transcription factors, cell cycle-related genes, and intracellular signaling cascade genes. However, downregulated genes include mitogen-activated protein kinases, cell cycle checkpoint genes, Rab subfamily genes, Rho subfamily genes, and SH2 and SH3 domains-related genes. These genes are involved in a broad range of different pathways including control of cell proliferation, differentiation, cell cycle, signal transduction, and apoptosis. Using the pathway visualization tool GenMAPP, we found that several genes, including TbR-I, STAT1, Smad1, Smad2, Jun, NFkappaB, and so on, in the TGF-beta signaling pathway and p115 RhoGEF, RhoGDI3, MEKK4A/MEKK4B, PI3KA, and JNK in the G13 signaling pathway were differentially expressed in the tumors. In summary, we have determined the expression profiles of genes differentially expressed during mouse bladder tumorigenesis. Our results suggest that activation of the EGFR-Ras pathway, uncontrolled cell cycle, aberrant transcription factors, and G13 and TGF-beta pathways are involved, and the cross-talk between these pathways seems to play important roles in mouse bladder tumorigenesis.
Collapse
Affiliation(s)
- Ruisheng Yao
- Department of Surgery and The Alvin J. Siteman Cancer Center, Campus Box 8109, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - William J Lemon
- Department of Surgery and The Alvin J. Siteman Cancer Center, Campus Box 8109, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Yian Wang
- Department of Surgery and The Alvin J. Siteman Cancer Center, Campus Box 8109, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Clinton J Grubbs
- Departments of Surgery, Genetics, and Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Ronald A Lubet
- Chemoprevention Agent Development Research Group, National Cancer Institute, Rockville, MD 20892, USA
| | - Ming You
- Department of Surgery and The Alvin J. Siteman Cancer Center, Campus Box 8109, Washington University School of Medicine, St. Louis, MO 63110, USA
| |
Collapse
|
20
|
Li GC, Guan LS, Wang ZY. Overexpression of RbAp46 facilitates stress-induced apoptosis and suppresses tumorigenicity of neoplastigenic breast epithelial cells. Int J Cancer 2003; 105:762-8. [PMID: 12767060 DOI: 10.1002/ijc.11148] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We have found previously that the retinoblastoma (Rb) suppressor associated protein 46 (RbAp46) is a gene upregulated by the Wilms' tumor suppressor, WT1, and functions as a potent growth inhibitor. To investigate the effect of RbAp46 overexpression on early development of breast cancer, we established stable cell lines from neoplastigenic breast epithelial cells, MCF10AT3B, a cell line derived from a model of human proliferative disease, to constitutively express exogenous RbAp46. We have found that expression of RbAp46 suppressed colony formation of MCF10AT3B cells in soft-agar, and inhibited tumor formation of these cells in nude mice. Expression of RbAp46 sensitized MCF10AT3B cells to apoptosis induced by serum deprivation and hydrocortisone withdrawal. Furthermore, we have found that the c-Jun NH2-terminal kinase (JNK) pathway and GADD45, a growth arrest- and DNA damage-inducible gene, are constitutively activated in RbAp46-expressing cells. Our data suggested that high levels of RbAp46 expression inhibit the tumorigenicity of neoplastigenic breast epithelial cells by facilitating JNK-dependent apoptotic cell death. Our data also suggested that dysregulation of RbAp46 gene may be involved in the early development of breast cancer.
Collapse
Affiliation(s)
- Guan-Cheng Li
- Division of Hematology and Oncology, Department of Medicine, Beth Israel-Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA
| | | | | |
Collapse
|
21
|
Yang J, Kiefer S, Rauchman M. Characterization of the gene encoding mouse retinoblastoma binding protein-7, a component of chromatin-remodeling complexes. Genomics 2002; 80:407-15. [PMID: 12376095 DOI: 10.1006/geno.2002.6844] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
RBBP7 is a highly conserved WD-repeat protein that interacts with histone deacetylases and is a component of several co-repressor complexes. The mouse gene Rbbp7 spans approximately 20 kb, consists of at least 12 exons, and contains a C/T polymorphism in the 3' splice acceptor region of intron 3. We found that Rbbp7 contains a TATA-less promoter with multiple transcription initiation sites. In transient transfection assays, we identified potential positive regulatory elements upstream of the proximal promoter at -668 to -1710. RBBP7 protein is detectable from at least day 9.5 of embryogenesis and is strongly expressed in the developing kidney and brain. Consistent with its association with co-repressor complexes, we demonstrate that RBBP7 represses the c-FOS transactivation domain in response to mitogen stimulation. We have also excluded human RBBP7 as a candidate gene in six patients that exhibit X-linked mental retardation, a heterogeneous developmental disorder that has been linked in some cases to mutations in genes involved in chromatin remodeling.
Collapse
Affiliation(s)
- Jing Yang
- Renal Division, Washington University School of Medicine, Box 8126, 660 S. Euclid Ave. St. Louis, Missouri 63110, USA
| | | | | |
Collapse
|
22
|
Abstract
Large proportions of hereditary breast cancers are due to mutations in the two breast cancer susceptibility genes BRCA1 and BRCA2. Considerable effort has gone into studying the function(s) of these tumor suppressor genes, both in attempts to better understand why individuals with these inherited mutations acquire breast (and ovarian) cancer and to potentially develop better treatment strategies. The advent of tools such as cDNA microarrays has enabled researchers to study global gene expression patterns in, for example, primary tumors, thus providing more comprehensive overviews of tumor development and progression. Our recent study (Hedenfalk et al., 2001) strongly supports the principle that genomic approaches to classification of hereditary breast cancers are possible, and that further studies will likely identify the most significant genes that discriminate between subgroups and may influence prognosis and treatment. A large number of hereditary breast cancer cases cannot be accounted for by mutations in these two genes and are believed to be due to as yet unidentified breast cancer predisposition genes (BRCAx). Subclassification of these non-BRCA1/2 breast cancers using cDNA microarray-based gene expression profiling, followed by linkage analysis and/or investigation of genomic alterations, may help in the recognition of novel breast cancer predisposition loci. To summarize, gene expression-based analysis of hereditary breast cancer can potentially be used for classification purposes, as well as to expand upon our knowledge of differences between different forms of hereditary breast cancer. Initial studies indicate that a patient's genotype does in fact leave an identifiable trace on her/his cancer's gene expression profile.
Collapse
Affiliation(s)
- Ingrid A Hedenfalk
- Cancer Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
| | | | | | | |
Collapse
|
23
|
Fan W, Jin S, Tong T, Zhao H, Fan F, Antinore MJ, Rajasekaran B, Wu M, Zhan Q. BRCA1 regulates GADD45 through its interactions with the OCT-1 and CAAT motifs. J Biol Chem 2002; 277:8061-7. [PMID: 11777930 DOI: 10.1074/jbc.m110225200] [Citation(s) in RCA: 107] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BRCA1, a breast and ovarian cancer susceptibility gene, has been implicated in gene regulation. Previous studies demonstrate that BRCA1 induces GADD45, a p53-regulated and stress-inducible gene that plays an important role in cellular response to DNA damage. However, the mechanism(s) by which BRCA1 regulates GADD45 remains unclear. In this report, we have shown that BRCA1 activation of the GADD45 promoter is mediated through the OCT-1 and CAAT motifs located at the GADD45 promoter region. Site-directed mutations of both OCT-1 and CAAT motifs abrogate induction of the GADD45 promoter by BRCA1. Both OCT-1 and CAAT motifs are able to confer BRCA1 inducibility in a non-related minimal promoter. Physical associations of BRCA1 protein with transcription factors Oct-1 and NF-YA, which directly bind to the OCT-1 and CAAT motifs, are established by biotin-streptavidin pull-down and coimmunoprecipitation assays. Such protein interactions are required for interaction of BRCA1 with the GADD45 promoter because either immunodepletion of Oct-1 and NF-YA proteins or mutations in the OCT-1 and CAAT motifs disrupt BRCA1 binding to the GADD45 promoter. These findings indicate that BRCA1 can up-regulate its targeted genes through protein-protein interactions and provide a novel mechanism by which BRCA1 participates in transcriptional regulation.
Collapse
Affiliation(s)
- Wenhong Fan
- Department of Radiation Oncology, Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA
| | | | | | | | | | | | | | | | | |
Collapse
|