1
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Lavoro A, Scalisi A, Candido S, Zanghì GN, Rizzo R, Gattuso G, Caruso G, Libra M, Falzone L. Identification of the most common BRCA alterations through analysis of germline mutation databases: Is droplet digital PCR an additional strategy for the assessment of such alterations in breast and ovarian cancer families? Int J Oncol 2022; 60:58. [PMID: 35383859 PMCID: PMC8997337 DOI: 10.3892/ijo.2022.5349] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Accepted: 03/24/2022] [Indexed: 11/06/2022] Open
Abstract
Breast and ovarian cancer represent two of the most common tumor types in females worldwide. Over the years, several non‑modifiable and modifiable risk factors have been associated with the onset and progression of these tumors, including age, reproductive factors, ethnicity, socioeconomic status and lifestyle factors, as well as family history and genetic factors. Of note, BRCA1 and BRCA2 are two tumor suppressor genes with a key role in DNA repair processes, whose mutations may induce genomic instability and increase the risk of cancer development. Specifically, females with a family history of breast or ovarian cancer harboring BRCA1/2 germline mutations have a 60‑70% increased risk of developing breast cancer and a 15‑40% increased risk for ovarian cancer. Different databases have collected the most frequent germline mutations affecting BRCA1/2. Through the analysis of such databases, it is possible to identify frequent hotspot mutations that may be analyzed with next‑generation sequencing (NGS) and novel innovative strategies. In this context, NGS remains the gold standard method for the assessment of BRCA1/2 mutations, while novel techniques, including droplet digital PCR (ddPCR), may improve the sensitivity to identify such mutations in the hereditary forms of breast and ovarian cancer. On these bases, the present study aimed to provide an update of the current knowledge on the frequency of BRCA1/2 mutations and cancer susceptibility, focusing on the diagnostic potential of the most recent methods, such as ddPCR.
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Affiliation(s)
- Alessandro Lavoro
- Department of Biomedical and Biotechnological Sciences, University of Catania, I‑95123 Catania, Italy
| | - Aurora Scalisi
- Italian League Against Cancer, Section of Catania, I‑95122 Catania, Italy
| | - Saverio Candido
- Department of Biomedical and Biotechnological Sciences, University of Catania, I‑95123 Catania, Italy
| | - Guido Nicola Zanghì
- Department of General Surgery and Medical‑Surgical Specialties, Policlinico‑Vittorio Emanuele Hospital, University of Catania, I‑95123 Catania, Italy
| | - Roberta Rizzo
- Department of Biomedical and Biotechnological Sciences, University of Catania, I‑95123 Catania, Italy
| | - Giuseppe Gattuso
- Department of Biomedical and Biotechnological Sciences, University of Catania, I‑95123 Catania, Italy
| | - Giuseppe Caruso
- Department of Biomedical and Biotechnological Sciences, University of Catania, I‑95123 Catania, Italy
| | - Massimo Libra
- Department of Biomedical and Biotechnological Sciences, University of Catania, I‑95123 Catania, Italy
| | - Luca Falzone
- Epidemiology and Biostatistics Unit, National Cancer Institute IRCCS Fondazione 'G. Pascale', I‑80131 Naples, Italy
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2
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Brosh RM, Wu Y. An emerging picture of FANCJ's role in G4 resolution to facilitate DNA replication. NAR Cancer 2021; 3:zcab034. [PMID: 34873585 DOI: 10.1093/narcan/zcab034] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 07/28/2021] [Accepted: 08/13/2021] [Indexed: 02/06/2023] Open
Abstract
A well-accepted hallmark of cancer is genomic instability, which drives tumorigenesis. Therefore, understanding the molecular and cellular defects that destabilize chromosomal integrity is paramount to cancer diagnosis, treatment and cure. DNA repair and the replication stress response are overarching paradigms for maintenance of genomic stability, but the devil is in the details. ATP-dependent helicases serve to unwind DNA so it is replicated, transcribed, recombined and repaired efficiently through coordination with other nucleic acid binding and metabolizing proteins. Alternatively folded DNA structures deviating from the conventional anti-parallel double helix pose serious challenges to normal genomic transactions. Accumulating evidence suggests that G-quadruplex (G4) DNA is problematic for replication. Although there are multiple human DNA helicases that can resolve G4 in vitro, it is debated which helicases are truly important to resolve such structures in vivo. Recent advances have begun to elucidate the principal helicase actors, particularly in cellular DNA replication. FANCJ, a DNA helicase implicated in cancer and the chromosomal instability disorder Fanconi Anemia, takes center stage in G4 resolution to allow smooth DNA replication. We will discuss FANCJ's role with its protein partner RPA to remove G4 obstacles during DNA synthesis, highlighting very recent advances and implications for cancer therapy.
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Affiliation(s)
- Robert M Brosh
- Translational Gerontology Branch, National Institute on Aging, NIH, Baltimore, MD 21224, USA
| | - Yuliang Wu
- Department of Biochemistry, Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
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3
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Xu L, Xu W, Li D, Yu X, Gao F, Qin Y, Yang Y, Zhao S. FANCI plays an essential role in spermatogenesis and regulates meiotic histone methylation. Cell Death Dis 2021; 12:780. [PMID: 34373449 PMCID: PMC8353022 DOI: 10.1038/s41419-021-04034-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/14/2021] [Accepted: 07/15/2021] [Indexed: 12/15/2022]
Abstract
FANCI is an essential component of Fanconi anemia pathway, which is responsible for the repair of DNA interstrand cross-links (ICLs). As an evolutionarily related partner of FANCD2, FANCI functions together with FANCD2 downstream of FA core complex. Currently, growing evidences showed that the essential role of FA pathway in male fertility. However, the underlying mechanisms for FANCI in regulating spermatogenesis remain unclear. In the present study, we found that the male Fanci−/− mice were sterile and exhibited abnormal spermatogenesis, including massive germ cell apoptosis in seminiferous tubules and dramatically decreased number of sperms in epididymis. Besides, FANCI deletion impaired maintenance of undifferentiated spermatogonia. Further investigation indicated that FANCI was essential for FANCD2 foci formation and regulated H3K4 and H3K9 methylation on meiotic sex chromosomes. These findings elucidate the role and mechanism of FANCI during spermatogenesis in mice and provide new insights into the etiology and molecular basis of nonobstructive azoospermia.
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Affiliation(s)
- Lan Xu
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Key laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, 250012, China.,Shandong Key Laboratory of Reproductive Medicine, Jinan, Shandong, 250012, China.,Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.,National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
| | - Weiwei Xu
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Key laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, 250012, China.,Shandong Key Laboratory of Reproductive Medicine, Jinan, Shandong, 250012, China.,Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.,National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
| | - Duan Li
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Key laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, 250012, China.,Shandong Key Laboratory of Reproductive Medicine, Jinan, Shandong, 250012, China.,Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.,National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
| | - Xiaoxia Yu
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Key laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, 250012, China.,Shandong Key Laboratory of Reproductive Medicine, Jinan, Shandong, 250012, China.,Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.,National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
| | - Fei Gao
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China.,University of Chinese Academy of Sciences, Beijing, 100101, China
| | - Yingying Qin
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China.,Key laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, 250012, China.,Shandong Key Laboratory of Reproductive Medicine, Jinan, Shandong, 250012, China.,Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China.,National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China
| | - Yajuan Yang
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China. .,Key laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, 250012, China. .,Shandong Key Laboratory of Reproductive Medicine, Jinan, Shandong, 250012, China. .,Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China. .,National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China. .,State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China. .,Yunnan Key Laboratory of Animal Reproduction, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan, 650223, China.
| | - Shidou Zhao
- Center for Reproductive Medicine, Cheeloo College of Medicine, Shandong University, Jinan, Shandong, 250012, China. .,Key laboratory of Reproductive Endocrinology of Ministry of Education, Shandong University, Jinan, Shandong, 250012, China. .,Shandong Key Laboratory of Reproductive Medicine, Jinan, Shandong, 250012, China. .,Shandong Provincial Clinical Research Center for Reproductive Health, Jinan, Shandong, 250012, China. .,National Research Center for Assisted Reproductive Technology and Reproductive Genetics, Shandong University, Jinan, Shandong, 250012, China.
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4
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Muhseena N K, Mathukkada S, Das SP, Laha S. The repair gene BACH1 - a potential oncogene. Oncol Rev 2021; 15:519. [PMID: 34322202 PMCID: PMC8273628 DOI: 10.4081/oncol.2021.519] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2020] [Accepted: 03/02/2021] [Indexed: 12/12/2022] Open
Abstract
BACH1 encodes for a protein that belongs to RecQ DEAH helicase family and interacts with the BRCT repeats of BRCA1. The N-terminus of BACH1 functions in DNA metabolism as DNA-dependent ATPase and helicase. The C-terminus consists of BRCT domain, which interacts with BRCA1 and this interaction is one of the major regulator of BACH1 function. BACH1 plays important roles both in phosphorylated as well as dephosphorylated state and functions in coordination with multiple signaling molecules. The active helicase property of BACH1 is maintained by its dephosphorylated state. Imbalance between these two states enhances the development and progression of the diseased condition. Currently BACH1 is known as a tumor suppressor gene based on the presence of its clinically relevant mutations in different cancers. Through this review we have justified it to be named as an oncogene. In this review, we have explained the mechanism of how BACH1 in collaboration with BRCA1 or independently regulates various pathways like cell cycle progression, DNA replication during both normal and stressed situation, recombination and repair of damaged DNA, chromatin remodeling and epigenetic modifications. Mutation and overexpression of BACH1 are significantly found in different cancer types. This review enlists the molecular players which interact with BACH1 to regulate DNA metabolic functions, thereby revealing its potential for cancer therapeutics. We have identified the most mutated functional domain of BACH1, the hot spot for tumorigenesis, justifying it as a target molecule in different cancer types for therapeutics. BACH1 has high potentials of transforming a normal cell into a tumor cell if compromised under certain circumstances. Thus, through this review, we justify BACH1 as an oncogene along with the existing role of being a tumor suppressant.
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Affiliation(s)
- Katheeja Muhseena N
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Sooraj Mathukkada
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Shankar Prasad Das
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
| | - Suparna Laha
- Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore, Karnataka, India
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5
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Calvo JA, Fritchman B, Hernandez D, Persky NS, Johannessen CM, Piccioni F, Kelch BA, Cantor SB. Comprehensive Mutational Analysis of the BRCA1-Associated DNA Helicase and Tumor-Suppressor FANCJ/BACH1/BRIP1. Mol Cancer Res 2021; 19:1015-1025. [PMID: 33619228 DOI: 10.1158/1541-7786.mcr-20-0828] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 01/27/2021] [Accepted: 02/18/2021] [Indexed: 12/15/2022]
Abstract
FANCJ (BRIP1/BACH1) is a hereditary breast and ovarian cancer (HBOC) gene encoding a DNA helicase. Similar to HBOC genes, BRCA1 and BRCA2, FANCJ is critical for processing DNA inter-strand crosslinks (ICL) induced by chemotherapeutics, such as cisplatin. Consequently, cells deficient in FANCJ or its catalytic activity are sensitive to ICL-inducing agents. Unfortunately, the majority of FANCJ clinical mutations remain uncharacterized, limiting therapeutic opportunities to effectively use cisplatin to treat tumors with mutated FANCJ. Here, we sought to perform a comprehensive screen to identify FANCJ loss-of-function (LOF) mutations. We developed a FANCJ lentivirus mutation library representing approximately 450 patient-derived FANCJ nonsense and missense mutations to introduce FANCJ mutants into FANCJ knockout (K/O) HeLa cells. We performed a high-throughput screen to identify FANCJ LOF mutants that, as compared with wild-type FANCJ, fail to robustly restore resistance to ICL-inducing agents, cisplatin or mitomycin C (MMC). On the basis of the failure to confer resistance to either cisplatin or MMC, we identified 26 missense and 25 nonsense LOF mutations. Nonsense mutations elucidated a relationship between location of truncation and ICL sensitivity, as the majority of nonsense mutations before amino acid 860 confer ICL sensitivity. Further validation of a subset of LOF mutations confirmed the ability of the screen to identify FANCJ mutations unable to confer ICL resistance. Finally, mapping the location of LOF mutations to a new homology model provides additional functional information. IMPLICATIONS: We identify 51 FANCJ LOF mutations, providing important classification of FANCJ mutations that will afford additional therapeutic strategies for affected patients.
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Affiliation(s)
- Jennifer A Calvo
- Department of Molecular Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Briana Fritchman
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | | | - Nicole S Persky
- The Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | | | | | - Brian A Kelch
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts
| | - Sharon B Cantor
- Department of Molecular Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, Massachusetts.
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6
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Ciccone MA, Adams CL, Bowen C, Thakur T, Ricker C, Culver JO, Maoz A, Melas M, Idos GE, Jeyasekharan AD, Matsuo K, Roman LD, Gruber SB, McDonnell KJ. Inhibition of poly(ADP-ribose) polymerase induces synthetic lethality in BRIP1 deficient ovarian epithelial cells. Gynecol Oncol 2020; 159:869-876. [PMID: 33032822 PMCID: PMC9893519 DOI: 10.1016/j.ygyno.2020.09.040] [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: 05/08/2020] [Accepted: 09/23/2020] [Indexed: 02/04/2023]
Abstract
OBJECTIVE Pathogenic variations in the homologous recombination (HR) gene, BRCA1 interacting protein C-terminal helicase 1 (BRIP1) increase the risk for ovarian cancer. PARP inhibitors (PARPi) exert a synthetic lethal effect in BRCA-mutated ovarian cancers. Effective HR requires cooperation between BRCA1 and BRIP1; therefore, BRIP1-incompetancy may predict vulnerability to synthetic lethality. Here we investigated the response of ovarian epithelial cells with defective BRIP1 function to PARPi, and compared these cells to those lacking BRCA1 activity. METHODS We engineered Chinese Hamster ovarian (CHO) epithelial cells to express deficient BRIP1 or BRCA1, and exposed them to olaparib with or without carboplatin or cisplatin. We assessed cellular proliferation and survival; we calculated inhibitory concentrations and combination and reduction drug indices. RESULTS BRIP1 and BRCA1 inactivation impedes HR activity, decreases cellular proliferation and compromises DNA damage recovery. Platinum agent exposure impairs cellular survival. Olaparib exposure alone decreases cell viability in BRCA1-deficient cells, although has no effect on BRIP1-deficient cells. Combining carboplatin or cisplatin with olaparib synergistically attenuates cellular survival, consistent with synthetic lethality. CONCLUSIONS BRIP1-deficient ovarian epithelial cells exhibit defective HR, resulting in synthetic lethality when exposed to a platinum agent/PARPi combination. PARPi alone had no effect; this lack of effect may result from distinguishing molecular properties of BRIP1and/or consequences of genomic background. Our study identifies altered BRIP1 as a target for precision medicine-based therapies for ovarian cancers. This investigation supports consideration of the use of a platinum agent/PARPi combination in ovarian cancers depending upon genetic profile and genomic background.
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Affiliation(s)
- Marcia A. Ciccone
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, USA,Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA,Corresponding Author: Marcia A. Ciccone, 2020 Zonal Ave, IRD 520, Los Angeles, CA, 90033, phone: (323) 409-3416, Fax: (323) 226-2734,
| | - Crystal L. Adams
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, USA,Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Charles Bowen
- Department of Clinical Cancer Prevention, Division of Cancer Prevention and Population Sciences, MD Anderson Cancer Center, Houston, TX, USA
| | - Teena Thakur
- Cancer Science Institute of Singapore, National University of Singapore, Singapore
| | - Charité Ricker
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, USA,Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Julie O. Culver
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, USA
| | - Asaf Maoz
- Department of Medicine, Boston University School of Medicine and Boston Medical Center, Boston University, Boston, MA, USA
| | - Marilena Melas
- The Steve and Cindy Rasmussen Institute for Genomic Medicine, Nationwide Children’s Hospital, Columbus, OH, USA
| | - Gregory E. Idos
- Department of Internal Medicine, Division of Gastroenterology, City of Hope Comprehensive Cancer Center, Duarte, CA, USA,Center for Precision Medicine, City of Hope National Medical Center, Duarte, CA, USA
| | | | - Koji Matsuo
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, USA,Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Lynda D. Roman
- USC Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA, USA,Department of Obstetrics and Gynecology, Division of Gynecologic Oncology, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Stephen B. Gruber
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, and Beckman Research Institute, Duarte, CA, USA,Center for Precision Medicine, City of Hope National Medical Center, Duarte, CA, USA
| | - Kevin J. McDonnell
- Department of Medical Oncology and Therapeutics Research, City of Hope National Medical Center, and Beckman Research Institute, Duarte, CA, USA,Center for Precision Medicine, City of Hope National Medical Center, Duarte, CA, USA
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7
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Wang J, Sun D, Lu W, Zhang Z, Zhang C, Hu K. BRIP1 rs10744996C>A variant increases the risk of chronic obstructive pulmonary disease in the Mongolian population of northern China. Exp Physiol 2020; 105:1950-1959. [PMID: 32851703 DOI: 10.1113/ep088210] [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: 09/24/2019] [Accepted: 08/25/2020] [Indexed: 01/16/2023]
Abstract
NEW FINDINGS What is the central question of this study? What is the role of breast cancer type 1 interacting protein C-terminal helicase 1 (BRIP1) polymorphism in chronic obstructive pulmonary disease (COPD)? What is the main finding and its importance? Variant rs10744996C>A of BRIP1 increases the susceptibility of the Mongolian population to COPD. The expression of BRIP1 was significantly reduced in cigarette smoke extract-treated airway epithelial cells. ABSTRACT Cigarette smoke is a major environmental pollutant that can induce DNA damage in humans. The development and progression of chronic obstructive pulmonary disease (COPD) are known to be related to the impairment of DNA repair. Breast cancer type 1 interacting protein C-terminal helicase 1 (BRIP1) plays an important role in DNA interstrand crosslink repair and double-strand break repair. However, the role of BRIP1 polymorphisms in COPD has not been previously described. In this study, whole genome sequencing was used to identify mutations, and single nucleotide polymorphism (SNP) genotyping was used to verify the selected SNPs. In addition the BRIP1 expression levels in 16HBE and A549 airway epithelial cells treated with or without cigarette smoke extract (CSE) were measured using western blotting and RT-qPCR. Rs10744996C>A in the 3'-untranslated region (3'UTR) of BRIP1 was then genotyped in 1296 COPD cases and 988 healthy control subjects from a Mongolian population in northern China. Significant differences in the distribution of rs10744996C>A variants between COPD and control groups (P = 0.001) were identified. Rs10744996C>A was found to be associated with significantly increased COPD risk (adjusted odds ratio = 1.60, 95% CI = 1.30-1.98, P < 0.0001). Additionally, rs10744996A genotype was found to interact with a family history of cancer and a history of x-ray exposure (P = 0.028 and 0.009, respectively). BRIP1 expression levels in 16HBE and A549 cells treated with CSE were significantly lower compared to the control treated cells. The rs10744996C>A variant of BRIP1 increased the COPD susceptibility of the Mongolian population cohort. BRIP1 mRNA and protein expression levels were significantly reduced in conjunction with CSE-induced DNA damage in 16HBE and A549 cells.
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Affiliation(s)
- Jing Wang
- Department of Respiratory and Critical Care Medicine, Renmin Hospital of Wuhan University, Wuhan, Hubei, China.,Department of Rehabilitation Medicine, Affiliated Hospital of Inner Mongolia Medical University, Hohhot, Inner Mongolia, China
| | - Dejun Sun
- Department of Pulmonary and Critical Care Medicine, Inner Mongolia Autonomous Region People's Hospital, Hohhot, Inner Mongolia, China
| | - Wenju Lu
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Zili Zhang
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Chenting Zhang
- State Key Laboratory of Respiratory Disease, Guangzhou Institute of Respiratory Health, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Ke Hu
- Department of Respiratory and Critical Care Medicine, Renmin Hospital of Wuhan University, Wuhan, Hubei, China
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8
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Regulation of Histone Ubiquitination in Response to DNA Double Strand Breaks. Cells 2020; 9:cells9071699. [PMID: 32708614 PMCID: PMC7407225 DOI: 10.3390/cells9071699] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 07/10/2020] [Accepted: 07/14/2020] [Indexed: 12/11/2022] Open
Abstract
Eukaryotic cells are constantly exposed to both endogenous and exogenous stressors that promote the induction of DNA damage. Of this damage, double strand breaks (DSBs) are the most lethal and must be efficiently repaired in order to maintain genomic integrity. Repair of DSBs occurs primarily through one of two major pathways: non-homologous end joining (NHEJ) or homologous recombination (HR). The choice between these pathways is in part regulated by histone post-translational modifications (PTMs) including ubiquitination. Ubiquitinated histones not only influence transcription and chromatin architecture at sites neighboring DSBs but serve as critical recruitment platforms for repair machinery as well. The reversal of these modifications by deubiquitinating enzymes (DUBs) is increasingly being recognized in a number of cellular processes including DSB repair. In this context, DUBs ensure proper levels of ubiquitin, regulate recruitment of downstream effectors, dictate repair pathway choice, and facilitate appropriate termination of the repair response. This review outlines the current understanding of histone ubiquitination in response to DSBs, followed by a comprehensive overview of the DUBs that catalyze the removal of these marks.
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9
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Nakamura K, Aimono E, Tanishima S, Imai M, Nagatsuma AK, Hayashi H, Yoshimura Y, Nakayama K, Kyo S, Nishihara H. Olaparib Monotherapy for BRIP1-Mutated High-Grade Serous Endometrial Cancer. JCO Precis Oncol 2020; 4:1900368. [PMID: 32923896 PMCID: PMC7446499 DOI: 10.1200/po.19.00368] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Kohei Nakamura
- Genomics Unit, Keio Cancer Center, Keio University School of Medicine, Tokyo, Japan.,Genomics Unit, Keio Cancer Center, Keio University School of Medicine, Tokyo, Japan
| | - Eriko Aimono
- Genomics Unit, Keio Cancer Center, Keio University School of Medicine, Tokyo, Japan
| | - Shigeki Tanishima
- Department of Biomedical Informatics, Kansai Division, Mitsubishi Space Software, Tokyo, Japan
| | - Mitsuho Imai
- Genomics Unit, Keio Cancer Center, Keio University School of Medicine, Tokyo, Japan
| | | | - Hideyuki Hayashi
- Genomics Unit, Keio Cancer Center, Keio University School of Medicine, Tokyo, Japan
| | - Yuki Yoshimura
- Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan
| | - Kentaro Nakayama
- Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan
| | - Satoru Kyo
- Department of Obstetrics and Gynecology, Shimane University School of Medicine, Izumo, Japan
| | - Hiroshi Nishihara
- Genomics Unit, Keio Cancer Center, Keio University School of Medicine, Tokyo, Japan
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10
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Moyer CL, Ivanovich J, Gillespie JL, Doberstein R, Radke MR, Richardson ME, Kaufmann SH, Swisher EM, Goodfellow PJ. Rare BRIP1 Missense Alleles Confer Risk for Ovarian and Breast Cancer. Cancer Res 2019; 80:857-867. [PMID: 31822495 DOI: 10.1158/0008-5472.can-19-1991] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 10/25/2019] [Accepted: 12/04/2019] [Indexed: 11/16/2022]
Abstract
Germline loss-of-function mutations in BRCA1 interacting protein C-terminal helicase 1 (BRIP1) are associated with ovarian carcinoma and may also contribute to breast cancer risk, particularly among patients who develop disease at an early age. Normal BRIP1 activity is required for DNA interstrand cross-link (ICL) repair and is thus central to the maintenance of genome stability. Although pathogenic mutations have been identified in BRIP1, genetic testing more often reveals missense variants, for which the impact on molecular function and subsequent roles in cancer risk are uncertain. Next-generation sequencing of germline DNA in 2,160 early-onset breast cancer and 1,199 patients with ovarian cancer revealed nearly 2% of patients carry a very rare missense variant (minor allele frequency < 0.0001) in BRIP1. This is 3-fold higher than the frequency of all rare BRIP1 missense alleles reported in more than 60,000 individuals of the general population (P < 0.0001, χ 2 test). Using CRISPR-Cas9 gene editing technology and rescue assays, we functionally characterized 20 of these missense variants, focusing on the altered protein's ability to repair ICL damage. A total of 75% of the characterized variants rendered the protein hypomorph or null. In a clinical cohort of >117,000 patients with breast and ovarian cancer who underwent panel testing, the combined OR associated with BRIP1 hypomorph or null missense carriers compared with the general population was 2.30 (95% confidence interval, 1.60-3.30; P < 0.0001). These findings suggest that novel missense variants within the helicase domain of BRIP1 may confer risk for both breast and ovarian cancer and highlight the importance of functional testing for additional variants. SIGNIFICANCE: Functional characterization of rare variants of uncertain significance in BRIP1 revealed that 75% demonstrate loss-of-function activity, suggesting rare missense alleles in BRIP1 confer risk for both breast and ovarian cancer.
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Affiliation(s)
- Cassandra L Moyer
- James Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
- Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
| | - Jennifer Ivanovich
- Department of Medical and Molecular Genetics, Indiana University, Indianapolis, Indiana
| | - Jessica L Gillespie
- James Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
- Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
| | - Rachel Doberstein
- James Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio
- Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
| | - Marc R Radke
- Division of Gynecologic Oncology, University of Washington, Seattle, Washington
| | - Marcy E Richardson
- Department of Clinical Genomics, Ambry Genetics, Aliso Viejo, California
| | - Scott H Kaufmann
- Division of Oncology Research, Mayo Clinic, Rochester, Minnesota
| | - Elizabeth M Swisher
- Division of Gynecologic Oncology, University of Washington, Seattle, Washington
| | - Paul J Goodfellow
- James Comprehensive Cancer Center, The Ohio State University, Columbus, Ohio.
- Department of Obstetrics and Gynecology, The Ohio State University, Columbus, Ohio
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11
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Nako T, Fukumoto H, Hasegawa H, Saeki H, Katano H. Functional Analysis of Trichodysplasia Spinulosa-Associated Polyomavirus-Encoded Large T Antigen. Jpn J Infect Dis 2019; 73:132-139. [PMID: 31787742 DOI: 10.7883/yoken.jjid.2019.391] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Trichodysplasia spinulosa-associated polyomavirus (TSPyV or human polyomavirus 8) was identified from patients with trichodysplasia spinulosa, a rare skin disease affecting the faces of immunocompromised patients. Like other polyomaviruses, the TSPyV genome encodes a large T antigen (LT). However, the expression and functions of TSPyV LT in infected cells remain largely unknown. In the present study, we cloned a full-length TSPyV LT cDNA from cells transfected with the full-length of TSPyV LT DNA. Transfection study using green fluorescence protein-tagged LT expression plasmids showed that TSPyV LT was expressed in the nucleus of transfected cells. Analysis of deletion mutants identified a nuclear localization signal in TSPyV LT. Recombinant TSPyV LT exhibited an ATPase activity. TSPyV LT has a chitinase-like domain; however, no chitinase activity was detected. Immunoprecipitation assays revealed that TSPyV LT bound to retinoblastoma 1, but not to p53 in transfected cells. Expression of TSPyV LT in NIH3T3 cells induced colony formation in soft agar, suggesting its transformation activity. These data indicate that TSPyV LT may be associated with the pathogenesis of trichodysplasia spinulosa, which is a hyperplasia of keratinocytes in inner hair follicles.
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Affiliation(s)
- Toshie Nako
- Department of Pathology, National Institute of Infectious Diseases.,Department of Dermatology, Nippon Medical School
| | - Hitomi Fukumoto
- Department of Pathology, National Institute of Infectious Diseases
| | - Hideki Hasegawa
- Department of Pathology, National Institute of Infectious Diseases
| | | | - Harutaka Katano
- Department of Pathology, National Institute of Infectious Diseases
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12
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Ben Haj Ali A, Amouri A, Sayeb M, Makni S, Hammami W, Naouali C, Dallali H, Romdhane L, Bashamboo A, McElreavey K, Abdelhak S, Messaoud O. Cytogenetic and molecular diagnosis of Fanconi anemia revealed two hidden phenotypes: Disorder of sex development and cerebro-oculo-facio-skeletal syndrome. Mol Genet Genomic Med 2019; 7:e00694. [PMID: 31124294 PMCID: PMC6625148 DOI: 10.1002/mgg3.694] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 02/14/2019] [Accepted: 04/01/2019] [Indexed: 12/11/2022] Open
Abstract
Background Several studies have shown a high rate of consanguinity and endogamy in North African populations. As a result, the frequency of autosomal recessive diseases is relatively high in the region with the co‐occurrence of two or more diseases. Methods We report here on a consanguineous Libyan family whose child was initially diagnosed as presenting Fanconi anemia (FA) with uncommon skeletal deformities. The chromosome breakage test has been performed using mitomycin C (MMC) while molecular analysis was performed by a combined approach of linkage analysis and whole exome sequencing. Results Cytogenetic analyses showed that the karyotype of the female patient is 46,XY suggesting the diagnosis of a disorder of sex development (DSD). By looking at the genetic etiology of FA and DSD, we have identified p.[Arg798*];[Arg798*] mutation in FANCJ (OMIM #605882) gene responsible for FA and p.[Arg108*];[Arg1497Trp] in EFCAB6 (Gene #64800) gene responsible for DSD. In addition, we have incidentally discovered a novel mutation p.[Gly1372Arg];[Gly1372Arg] in the ERCC6 (CSB) (OMIM #609413) gene responsible for COFS that might explain the atypical severe skeletal deformities. Conclusion The co‐occurrence of clinical and overlapping genetic heterogeneous entities should be taken into consideration for better molecular and genetic counseling.
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Affiliation(s)
- Abir Ben Haj Ali
- Laboratory of Histology and Cytogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia.,Laboratory of Biomedical Genomics and Oncogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Ahlem Amouri
- Laboratory of Histology and Cytogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia.,Laboratory of Biomedical Genomics and Oncogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Marwa Sayeb
- Laboratory of Biomedical Genomics and Oncogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia
| | | | - Wajih Hammami
- Laboratory of Histology and Cytogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia.,Laboratory of Biomedical Genomics and Oncogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Chokri Naouali
- Laboratory of Biomedical Genomics and Oncogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Hamza Dallali
- Laboratory of Biomedical Genomics and Oncogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Lilia Romdhane
- Laboratory of Biomedical Genomics and Oncogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Anu Bashamboo
- Human Developmental Genetics, Institut Pasteur de Paris, Paris, France
| | | | - Sonia Abdelhak
- Laboratory of Biomedical Genomics and Oncogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia
| | - Olfa Messaoud
- Laboratory of Biomedical Genomics and Oncogenetics, Institut Pasteur de Tunis, University Tunis El Manar, Tunis, Tunisia
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13
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Griffin WC, Trakselis MA. The MCM8/9 complex: A recent recruit to the roster of helicases involved in genome maintenance. DNA Repair (Amst) 2019; 76:1-10. [PMID: 30743181 DOI: 10.1016/j.dnarep.2019.02.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 02/03/2019] [Indexed: 12/11/2022]
Abstract
There are several DNA helicases involved in seemingly overlapping aspects of homologous and homoeologous recombination. Mutations of many of these helicases are directly implicated in genetic diseases including cancer, rapid aging, and infertility. MCM8/9 are recent additions to the catalog of helicases involved in recombination, and so far, the evidence is sparse, making assignment of function difficult. Mutations in MCM8/9 correlate principally with primary ovarian failure/insufficiency (POF/POI) and infertility indicating a meiotic defect. However, they also act when replication forks collapse/break shuttling products into mitotic recombination and several mutations are found in various somatic cancers. This review puts MCM8/9 in context with other replication and recombination helicases to narrow down its genomic maintenance role. We discuss the known structure/function relationship, the mutational spectrum, and dissect the available cellular and organismal data to better define its role in recombination.
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Affiliation(s)
- Wezley C Griffin
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, 76798, USA
| | - Michael A Trakselis
- Department of Chemistry and Biochemistry, Baylor University, Waco, Texas, 76798, USA.
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14
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Peng M, Cong K, Panzarino NJ, Nayak S, Calvo J, Deng B, Zhu LJ, Morocz M, Hegedus L, Haracska L, Cantor SB. Opposing Roles of FANCJ and HLTF Protect Forks and Restrain Replication during Stress. Cell Rep 2018; 24:3251-3261. [PMID: 30232006 PMCID: PMC6218949 DOI: 10.1016/j.celrep.2018.08.065] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2018] [Revised: 06/23/2018] [Accepted: 08/22/2018] [Indexed: 02/07/2023] Open
Abstract
The DNA helicase FANCJ is mutated in hereditary breast and ovarian cancer and Fanconi anemia (FA). Nevertheless, how loss of FANCJ translates to disease pathogenesis remains unclear. We addressed this question by analyzing proteins associated with replication forks in cells with or without FANCJ. We demonstrate that FANCJ-knockout (FANCJ-KO) cells have alterations in the replisome that are consistent with enhanced replication stress, including an aberrant accumulation of the fork remodeling factor helicase-like transcription factor (HLTF). Correspondingly, HLTF contributes to fork degradation in FANCJ-KO cells. Unexpectedly, the unrestrained DNA synthesis that characterizes HLTF-deficient cells is FANCJ dependent and correlates with S1 nuclease sensitivity and fork degradation. These results suggest that FANCJ and HLTF promote replication fork integrity, in part by counteracting each other to keep fork remodeling and elongation in check. Indicating one protein compensates for loss of the other, loss of both HLTF and FANCJ causes a more severe replication stress response.
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Affiliation(s)
- Min Peng
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Ke Cong
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Nicholas J Panzarino
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Sumeet Nayak
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Jennifer Calvo
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Bin Deng
- Department of Biology/VGN Proteomics Facility, University of Vermont, Burlington, VT 05405, USA
| | - Lihua Julie Zhu
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Monika Morocz
- Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged 6726, Temesvari krt. 62, Hungary
| | - Lili Hegedus
- Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged 6726, Temesvari krt. 62, Hungary
| | - Lajos Haracska
- Institute of Genetics, Biological Research Center, Hungarian Academy of Sciences, Szeged 6726, Temesvari krt. 62, Hungary
| | - Sharon B Cantor
- Department of Molecular, Cell and Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
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15
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Takaoka M, Miki Y. BRCA1 gene: function and deficiency. Int J Clin Oncol 2017; 23:36-44. [PMID: 28884397 DOI: 10.1007/s10147-017-1182-2] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 08/17/2017] [Indexed: 10/18/2022]
Abstract
The BRCA1 protein, a hereditary breast and ovarian cancer-causing gene product, is known as a multifunctional protein that performs various functions in cells. It is well known, along with BRCA 2, to cause hereditary breast and ovarian cancer, but here we will specifically focus on BRCA1. We introduce the mechanism and the latest report on homologous recombination repair, replication, involvement in checkpoint regulation, transcription, chromatin remodeling, and cytoplasmic function (centrosome regulation, apoptosis, selective autophagy), and consider the possibility of carcinogenesis from inhibition of the intracellular functions in each. We also consider the possibility of drug development based on each function. Finally, we will explain, from data obtained through basic research, that an appropriate regimen is important for raising the response rate for poly (ADP)-ribose polymerase inhibitors, in the case of low susceptibility, iatrogenic toxicity, tolerance, etc.
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Affiliation(s)
- Miho Takaoka
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan
| | - Yoshio Miki
- Department of Molecular Genetics, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8510, Japan. .,Department of Genetic Diagnosis, The Cancer Institute, Japanese Foundation for Cancer Research, 3-10-6 Ariake, Koto-ku, Tokyo, 135-8550, Japan.
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16
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Beckta JM, Dever SM, Gnawali N, Khalil A, Sule A, Golding SE, Rosenberg E, Narayanan A, Kehn-Hall K, Xu B, Povirk LF, Valerie K. Mutation of the BRCA1 SQ-cluster results in aberrant mitosis, reduced homologous recombination, and a compensatory increase in non-homologous end joining. Oncotarget 2016; 6:27674-87. [PMID: 26320175 PMCID: PMC4695017 DOI: 10.18632/oncotarget.4876] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 07/31/2015] [Indexed: 11/25/2022] Open
Abstract
Mutations in the breast cancer susceptibility 1 (BRCA1) gene are catalysts for breast and ovarian cancers. Most mutations are associated with the BRCA1 N- and C-terminal domains linked to DNA double-strand break (DSB) repair. However, little is known about the role of the intervening serine-glutamine (SQ) - cluster in the DNA damage response beyond its importance in regulating cell cycle checkpoints. We show that serine-to-alanine alterations at critical residues within the SQ-cluster known to be phosphorylated by ATM and ATR result in reduced homologous recombination repair (HRR) and aberrant mitosis. While a S1387A BRCA1 mutant - previously shown to abrogate S-phase arrest in response to radiation - resulted in only a modest decrease in HRR, S1387A together with an additional alteration, S1423A (BRCA12P), reduced HRR to vector control levels and similar to a quadruple mutant also including S1457A and S1524A (BRCA14P). These effects appeared to be independent of PALB2. Furthermore, we found that BRCA14P promoted a prolonged and struggling HRR late in the cell cycle and shifted DSB repair from HRR to non-homologous end joining which, in the face of irreparable chromosomal damage, resulted in mitotic catastrophe. Altogether, SQ-cluster phosphorylation is critical for allowing adequate time for completing normal HRR prior to mitosis and preventing cells from entering G1 prematurely resulting in gross chromosomal aberrations.
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Affiliation(s)
- Jason M Beckta
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298, USA.,Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Seth M Dever
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298, USA.,Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Nisha Gnawali
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Ashraf Khalil
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Amrita Sule
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298, USA.,Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Sarah E Golding
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Elizabeth Rosenberg
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Aarthi Narayanan
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA 20110, USA
| | - Kylene Kehn-Hall
- National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA 20110, USA
| | - Bo Xu
- Cancer Research Department, Southern Research Institute, Birmingham, AL 35205, USA
| | - Lawrence F Povirk
- Department of Pharmacology and Toxicology, Virginia Commonwealth University, Richmond, VA 23298, USA
| | - Kristoffer Valerie
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA 23298, USA.,Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, VA 23298, USA.,Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, USA
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17
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Her J, Soo Lee N, Kim Y, Kim H. Factors forming the BRCA1-A complex orchestrate BRCA1 recruitment to the sites of DNA damage. Acta Biochim Biophys Sin (Shanghai) 2016; 48:658-64. [PMID: 27325824 DOI: 10.1093/abbs/gmw047] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2016] [Accepted: 04/18/2016] [Indexed: 12/28/2022] Open
Abstract
Sustaining genomic integrity is essential for preventing onset of cancers. Therefore, human cells evolve to have refined biological pathways to defend genetic materials from various genomic insults. DNA damage response and DNA repair pathways essential for genome maintenance are accomplished by cooperative executions of multiple factors including breast cancer type 1 susceptibility protein (BRCA1). BRCA1 is initially identified as an altered gene in the hereditary breast cancer patients. Since then, tremendous efforts to understand the functions of BRAC1 reveal that BRCA1 is found in distinct complexes, including BRCA1-A, BRCA1-B, BRCA1-C, and the BRCA1/PALB2/BRCA2 complex, and plays diverse roles in a context-dependent manner. Among the complexes, BRCA1-A is critical for BRCA1 recruitment to the sites of DNA damage. Factors comprising the BRCA1-A include RAP80, CCDC98/Abraxas, BRCC36, BRCC45, BARD1, BRCA1, and MERIT40, a RAP80-associated factor. In this review, we summarize recent findings of the factors that form the BRCA1-A complex.
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Affiliation(s)
- Joonyoung Her
- Department of Biological Sciences, Sookmyung Women's University, Seoul 04310, Republic of Korea
| | - Nam Soo Lee
- Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746, Republic of Korea
| | - Yonghwan Kim
- Department of Biological Sciences, Sookmyung Women's University, Seoul 04310, Republic of Korea
| | - Hongtae Kim
- Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746, Republic of Korea Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 440-746, Republic of Korea
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18
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Bick G, Zhang F, Meetei AR, Andreassen PR. Coordination of the recruitment of the FANCD2 and PALB2 Fanconi anemia proteins by an ubiquitin signaling network. Chromosoma 2016; 126:417-430. [PMID: 27277787 DOI: 10.1007/s00412-016-0602-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 05/11/2016] [Accepted: 05/13/2016] [Indexed: 12/26/2022]
Abstract
Fanconi anemia (FA) is a chromosome instability syndrome and the 20 identified FA proteins are organized into two main arms which are thought to function at distinct steps in the repair of DNA interstrand crosslinks (ICLs). These two arms include the upstream FA pathway, which culminates in the monoubiquitination of FANCD2 and FANCI, and downstream breast cancer (BRCA)-associated proteins that interact in protein complexes. How, and whether, these two groups of FA proteins are integrated is unclear. Here, we show that FANCD2 and PALB2, as indicators of the upstream and downstream arms, respectively, colocalize independently of each other in response to DNA damage induced by mitomycin C (MMC). We also show that ubiquitin chains are induced by MMC and colocalize with both FANCD2 and PALB2. Our finding that the RNF8 E3 ligase has a role in recruiting FANCD2 and PALB2 also provides support for the hypothesis that the two branches of the FA-BRCA pathway are coordinated by ubiquitin signaling. Interestingly, we find that the RNF8 partner, MDC1, as well as the ubiquitin-binding protein, RAP80, specifically recruit PALB2, while a different ubiquitin-binding protein, FAAP20, functions only in the recruitment of FANCD2. Thus, FANCD2 and PALB2 are not recruited in a single linear pathway, rather we define how their localization is coordinated and integrated by a network of ubiquitin-related proteins. We propose that such regulation may enable upstream and downstream FA proteins to act at distinct steps in the repair of ICLs.
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Affiliation(s)
- Gregory Bick
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - Fan Zhang
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA
| | - A Ruhikanta Meetei
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA.,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA
| | - Paul R Andreassen
- Division of Experimental Hematology and Cancer Biology, Cancer and Blood Diseases Institute, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, 45229, USA. .,Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, 45229, USA.
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19
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Mutational analysis of FANCJ helicase. Methods 2016; 108:118-29. [PMID: 27107905 DOI: 10.1016/j.ymeth.2016.04.023] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2016] [Revised: 04/15/2016] [Accepted: 04/19/2016] [Indexed: 11/21/2022] Open
Abstract
FANCJ is a superfamily 2 DNA helicase, which also belongs to the iron-sulfur domain containing helicases that include XPD, ChlR1 (DDX11), and RTEL1. Mutations in FANCJ are genetically linked to Fanconi anemia (FA), breast cancer, and ovarian cancer. FANCJ plays a critical role in genome stability and participates in DNA interstrand crosslink and double-strand break repair. Enormous sequence alterations in exons and introns of FANCJ have been identified in patients, including 15 mutations in the coding region which are linked to breast cancer, 12 to FA, and two to ovarian cancer. We and other groups have characterized several FANCJ missense mutations, including M299I, A349P, R251C, and Q255H. As an increasing number of clinically relevant FANCJ mutations are identified, understanding the mechanism whereby FANCJ mutation leads to diseases is critical. Mutational analysis of FANCJ will help us elucidate the pathogenesis and potentially lead to therapeutic strategies by targeting FANCJ.
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20
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Cantor SB, Nayak S. FANCJ at the FORK. Mutat Res 2016; 788:7-11. [PMID: 26926912 DOI: 10.1016/j.mrfmmm.2016.02.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2015] [Revised: 01/28/2016] [Accepted: 02/10/2016] [Indexed: 12/19/2022]
Affiliation(s)
- Sharon B Cantor
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, UMASS Memorial Cancer Center, Worcester, Massachusetts 01605, USA.
| | - Sumeet Nayak
- Department of Molecular, Cell, and Cancer Biology, University of Massachusetts Medical School, UMASS Memorial Cancer Center, Worcester, Massachusetts 01605, USA
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21
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Sun X, Brieño-Enríquez MA, Cornelius A, Modzelewski AJ, Maley TT, Campbell-Peterson KM, Holloway JK, Cohen PE. FancJ (Brip1) loss-of-function allele results in spermatogonial cell depletion during embryogenesis and altered processing of crossover sites during meiotic prophase I in mice. Chromosoma 2015; 125:237-52. [PMID: 26490168 DOI: 10.1007/s00412-015-0549-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 10/05/2015] [Accepted: 10/07/2015] [Indexed: 01/08/2023]
Abstract
Fancj, the gene associated with Fanconi anemia (FA) Complementation Group J, encodes a DNA helicase involved in homologous recombination repair and the cellular response to replication stress. FANCJ functions in part through its interaction with key DNA repair proteins, including MutL homolog-1 (MLH1), Breast Cancer Associated gene-1 (BRCA1), and Bloom syndrome helicase (BLM). All three of these proteins are involved in a variety of events that ensure genome stability, including the events of DNA double strand break (DSB) repair during prophase I of meiosis. Meiotic DSBs are repaired through homologous recombination resulting in non-crossovers (NCO) or crossovers (CO). The frequency and placement of COs are stringently regulated to ensure that each chromosome receives at least one CO event, and that longer chromosomes receive at least one additional CO, thus facilitating the accurate segregation of homologous chromosomes at the first meiotic division. In the present study, we investigated the role of Fancj during prophase I using a gene trap mutant allele. Fancj (GT/GT) mutants are fertile, but their testes are very much smaller than wild-type littermates, predominantly as a result of impeded spermatogonial proliferation and mildly increased apoptosis during testis development in the fetus. This defect in spermatogonial proliferation is consistent with mutations in other FA genes. During prophase I, early events of synapsis and DSB induction/repair appear mostly normal in Fancj (GT/GT) males, and the FANCJ-interacting protein BRCA1 assembles normally on meiotic chromosome cores. However, MLH1 focus frequency is increased in Fancj (GT/GT) males, indicative of increased DSB repair via CO, and is concomitant with increased chiasmata at diakinesis. This increase in COs in the absence of FANCJ is associated with increased localization of BLM helicase protein, indicating that BLM may facilitate the increased rate of crossing over in Fancj (GT/GT) males. Taken together, these results demonstrate a critical role for FANCJ in spermatogenesis at two stages: firstly in the proliferative activity that gives rise to the full complement of testicular spermatogonia and secondly in the establishment of appropriate CO numbers during prophase I.
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Affiliation(s)
- Xianfei Sun
- Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, Tower Road, Ithaca, NY, 14853, USA
| | - Miguel A Brieño-Enríquez
- Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, Tower Road, Ithaca, NY, 14853, USA
| | - Alyssa Cornelius
- Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, Tower Road, Ithaca, NY, 14853, USA
| | - Andrew J Modzelewski
- Department of Molecular and Cellular Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Tyler T Maley
- Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, Tower Road, Ithaca, NY, 14853, USA
| | - Kadeine M Campbell-Peterson
- Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, Tower Road, Ithaca, NY, 14853, USA
| | - J Kim Holloway
- Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, Tower Road, Ithaca, NY, 14853, USA
| | - Paula E Cohen
- Department of Biomedical Sciences and Center for Reproductive Genomics, Cornell University, Tower Road, Ithaca, NY, 14853, USA.
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22
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Clark DW, Tripathi K, Dorsman JC, Palle K. FANCJ protein is important for the stability of FANCD2/FANCI proteins and protects them from proteasome and caspase-3 dependent degradation. Oncotarget 2015; 6:28816-32. [PMID: 26336824 PMCID: PMC4745694 DOI: 10.18632/oncotarget.5006] [Citation(s) in RCA: 15] [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: 06/17/2015] [Accepted: 08/11/2015] [Indexed: 01/31/2023] Open
Abstract
Fanconi anemia (FA) is a rare genome instability syndrome with progressive bone marrow failure and cancer susceptibility. FANCJ is one of 17 genes mutated in FA-patients, comprises a DNA helicase that is vital for properly maintaining genomic stability and is known to function in the FA-BRCA DNA repair pathway. While exact role(s) of FANCJ in this repair process is yet to be determined, it is known to interact with primary effector FANCD2. However, FANCJ is not required for FANCD2 activation but is important for its ability to fully respond to DNA damage. In this report, we determined that transient depletion of FANCJ adversely affects stability of FANCD2 and its co-regulator FANCI in multiple cell lines. Loss of FANCJ does not significantly alter cell cycle progression or FANCD2 transcription. However, in the absence of FANCJ, the majority of FANCD2 is degraded by both the proteasome and Caspase-3 dependent mechanism. FANCJ is capable of complexing with and stabilizing FANCD2 even in the absence of a functional helicase domain. Furthermore, our data demonstrate that FANCJ is important for FANCD2 stability and proper activation of DNA damage responses to replication blocks induced by hydroxyurea.
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Affiliation(s)
- David W. Clark
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA
| | - Kaushlendra Tripathi
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA
| | - Josephine C. Dorsman
- Department of Clinical Genetics, Section Oncogenetics, VU University Medical Center, Amsterdam, The Netherlands
| | - Komaraiah Palle
- Department of Oncologic Sciences, Mitchell Cancer Institute, University of South Alabama, Mobile, Alabama, USA
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23
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Kato Y, Alavattam KG, Sin HS, Meetei AR, Pang Q, Andreassen PR, Namekawa SH. FANCB is essential in the male germline and regulates H3K9 methylation on the sex chromosomes during meiosis. Hum Mol Genet 2015; 24:5234-49. [PMID: 26123487 DOI: 10.1093/hmg/ddv244] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Accepted: 06/22/2015] [Indexed: 11/13/2022] Open
Abstract
Fanconi anemia (FA) is a recessive X-linked and autosomal genetic disease associated with bone marrow failure and increased cancer, as well as severe germline defects such as hypogonadism and germ cell depletion. Although deficiencies in FA factors are commonly associated with germ cell defects, it remains unknown whether the FA pathway is involved in unique epigenetic events in germ cells. In this study, we generated Fancb mutant mice, the first mouse model of X-linked FA, and identified a novel function of the FA pathway in epigenetic regulation during mammalian gametogenesis. Fancb mutant mice were infertile and exhibited primordial germ cell (PGC) defects during embryogenesis. Further, Fancb mutation resulted in the reduction of undifferentiated spermatogonia in spermatogenesis, suggesting that FANCB regulates the maintenance of undifferentiated spermatogonia. Additionally, based on functional studies, we dissected the pathway in which FANCB functions during meiosis. The localization of FANCB on sex chromosomes is dependent on MDC1, a binding partner of H2AX phosphorylated at serine 139 (γH2AX), which initiates chromosome-wide silencing. Also, FANCB is required for FANCD2 localization during meiosis, suggesting that the role of FANCB in the activation of the FA pathway is common to both meiosis and somatic DNA damage responses. H3K9me2, a silent epigenetic mark, was decreased on sex chromosomes, whereas H3K9me3 was increased on sex chromosomes in Fancb mutant spermatocytes. Taken together, these results indicate that FANCB functions at critical stages of germ cell development and reveal a novel function of the FA pathway in the regulation of H3K9 methylation in the germline.
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Affiliation(s)
- Yasuko Kato
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 4929, USA
| | - Kris G Alavattam
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 4929, USA
| | - Ho-Su Sin
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 4929, USA
| | - Amom Ruhikanta Meetei
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 4929, USA
| | - Qishen Pang
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 4929, USA
| | - Paul R Andreassen
- Division of Experimental Hematology and Cancer Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA and Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 4929, USA
| | - Satoshi H Namekawa
- Division of Reproductive Sciences, Division of Developmental Biology, Perinatal Institute, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 4929, USA
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24
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Aarts M, Bajrami I, Herrera-Abreu MT, Elliott R, Brough R, Ashworth A, Lord CJ, Turner NC. Functional Genetic Screen Identifies Increased Sensitivity to WEE1 Inhibition in Cells with Defects in Fanconi Anemia and HR Pathways. Mol Cancer Ther 2015; 14:865-76. [PMID: 25673822 PMCID: PMC6485454 DOI: 10.1158/1535-7163.mct-14-0845] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 02/04/2015] [Indexed: 01/11/2023]
Abstract
WEE1 kinase regulates CDK1 and CDK2 activity to facilitate DNA replication during S-phase and to prevent unscheduled entry into mitosis. WEE1 inhibitors synergize with DNA-damaging agents that arrest cells in S-phase by triggering direct mitotic entry without completing DNA synthesis, resulting in catastrophic chromosome fragmentation and apoptosis. Here, we investigated how WEE1 inhibition could be best exploited for cancer therapy by performing a functional genetic screen to identify novel determinants of sensitivity to WEE1 inhibition. Inhibition of kinases that regulate CDK activity, CHK1 and MYT1, synergized with WEE1 inhibition through both increased replication stress and forced mitotic entry of S-phase cells. Loss of multiple components of the Fanconi anemia (FA) and homologous recombination (HR) pathways, in particular DNA helicases, sensitized to WEE1 inhibition. Silencing of FA/HR genes resulted in excessive replication stress and nucleotide depletion following WEE1 inhibition, which ultimately led to increased unscheduled mitotic entry. Our results suggest that cancers with defects in FA and HR pathways may be targeted by WEE1 inhibition, providing a basis for a novel synthetic lethal strategy for cancers harboring FA/HR defects.
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Affiliation(s)
- Marieke Aarts
- CRUK Gene Function Laboratory, Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom
| | - Ilirjana Bajrami
- CRUK Gene Function Laboratory, Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom
| | - Maria T Herrera-Abreu
- CRUK Gene Function Laboratory, Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom
| | - Richard Elliott
- CRUK Gene Function Laboratory, Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom
| | - Rachel Brough
- CRUK Gene Function Laboratory, Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom
| | - Alan Ashworth
- CRUK Gene Function Laboratory, Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom
| | - Christopher J Lord
- CRUK Gene Function Laboratory, Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom
| | - Nicholas C Turner
- CRUK Gene Function Laboratory, Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, London, United Kingdom. Breast Unit, Royal Marsden Hospital, London, United Kingdom.
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25
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Guo M, Hundseth K, Ding H, Vidhyasagar V, Inoue A, Nguyen CH, Zain R, Lee JS, Wu Y. A distinct triplex DNA unwinding activity of ChlR1 helicase. J Biol Chem 2015; 290:5174-5189. [PMID: 25561740 DOI: 10.1074/jbc.m114.634923] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Mutations in the human ChlR1 (DDX11) gene are associated with a unique genetic disorder known as Warsaw breakage syndrome characterized by cellular defects in genome maintenance. The DNA triplex helix structures that form by Hoogsteen or reverse Hoogsteen hydrogen bonding are examples of alternate DNA structures that can be a source of genomic instability. In this study, we have examined the ability of human ChlR1 helicase to destabilize DNA triplexes. Biochemical studies demonstrated that ChlR1 efficiently melted both intermolecular and intramolecular DNA triplex substrates in an ATP-dependent manner. Compared with other substrates such as replication fork and G-quadruplex DNA, triplex DNA was a preferred substrate for ChlR1. Also, compared with FANCJ, a helicase of the same family, the triplex resolving activity of ChlR1 is unique. On the other hand, the mutant protein from a Warsaw breakage syndrome patient failed to unwind these triplexes. A previously characterized triplex DNA-specific antibody (Jel 466) bound triplex DNA structures and inhibited ChlR1 unwinding activity. Moreover, cellular assays demonstrated that there were increased triplex DNA content and double-stranded breaks in ChlR1-depleted cells, but not in FANCJ(-/-) cells, when cells were treated with a triplex stabilizing compound benzoquinoquinoxaline, suggesting that ChlR1 melting of triple-helix structures is distinctive and physiologically important to defend genome integrity. On the basis of our results, we conclude that the abundance of ChlR1 known to exist in vivo is likely to be a strong deterrent to the stability of triplexes that can potentially form in the human genome.
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Affiliation(s)
- Manhong Guo
- From the Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Kristian Hundseth
- From the Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Hao Ding
- From the Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | | | - Akira Inoue
- the Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital, Memphis, Tennessee 38105
| | - Chi-Hung Nguyen
- UMR176 CNRS-Institut Curie, Laboratoire de Pharmacochimie, Centre Universitaire, 91405 Orsay, France, and
| | - Rula Zain
- the Department of Laboratory Medicine, Clinical Research Center, Karolinska Institutet, 141 86 Huddinge, Stockholm, Sweden
| | - Jeremy S Lee
- From the Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada
| | - Yuliang Wu
- From the Department of Biochemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E5, Canada,.
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26
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Kumaraswamy E, Wendt KL, Augustine LA, Stecklein SR, Sibala EC, Li D, Gunewardena S, Jensen RA. BRCA1 regulation of epidermal growth factor receptor (EGFR) expression in human breast cancer cells involves microRNA-146a and is critical for its tumor suppressor function. Oncogene 2014; 34:4333-46. [PMID: 25417703 DOI: 10.1038/onc.2014.363] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Revised: 09/03/2014] [Accepted: 09/05/2014] [Indexed: 01/27/2023]
Abstract
Breast cancer 1 (BRCA1)-associated breast cancers are mostly basal-like high-grade ductal carcinomas that frequently overexpress epidermal growth factor receptor (EGFR). Aberrant EGFR expression is correlated with disease progression, resistance to radiation and chemotherapy, and poor clinical prognosis. Although BRCA1 is involved in multiple cellular processes, its functional role in EGFR regulation remains enigmatic. Here, we report a previously unrecognized posttranscriptional mechanism by which BRCA1 regulates EGFR expression through the induction of miR-146a. We demonstrate that EGFR expression correlates negatively with BRCA1, whereas miR-146a levels increase with BRCA1. We show that BRCA1 binds to MIR146A promoter and activates transcription, which in turn attenuates EGFR expression. Knockdown of miR-146a in BRCA1-overexpressing cells negated this effect and suppressed its ability to inhibit proliferation and transformation. In archived triple-negative breast cancer samples, we show a strong positive correlation between BRCA1 and miR-146a expression. We also show that low expression of miR-146a strongly predicts positive lymph node status and is associated with distinctively poor overall survival of patients. Together, these observations provide an insight into a novel BRCA1miR-146aEGFR paradigm by which BRCA1 carries out an aspect of tumor suppressor function that is potentially amenable to therapeutic intervention.
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Affiliation(s)
- E Kumaraswamy
- 1] Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, USA [2] The University of Kansas Cancer Center, Kansas City, KS, USA
| | - K L Wendt
- The University of Kansas Cancer Center, Kansas City, KS, USA
| | - L A Augustine
- The University of Kansas Cancer Center, Kansas City, KS, USA
| | - S R Stecklein
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, USA
| | - E C Sibala
- The University of Kansas Cancer Center, Kansas City, KS, USA
| | - D Li
- The University of Kansas Cancer Center, Kansas City, KS, USA
| | - S Gunewardena
- 1] Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, USA [2] Department of Biostatistics, University of Kansas Medical Center, Kansas City, KS, USA
| | - R A Jensen
- 1] Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, USA [2] The University of Kansas Cancer Center, Kansas City, KS, USA [3] Department of Cancer Biology, University of Kansas Medical Center, Kansas City, KS, USA [4] Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS, USA [5] Department of Molecular Biosciences, University of Kansas, Lawrence, KS, USA
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27
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Brosh RM, Cantor SB. Molecular and cellular functions of the FANCJ DNA helicase defective in cancer and in Fanconi anemia. Front Genet 2014; 5:372. [PMID: 25374583 PMCID: PMC4204437 DOI: 10.3389/fgene.2014.00372] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/05/2014] [Indexed: 01/11/2023] Open
Abstract
The FANCJ DNA helicase is mutated in hereditary breast and ovarian cancer as well as the progressive bone marrow failure disorder Fanconi anemia (FA). FANCJ is linked to cancer suppression and DNA double strand break repair through its direct interaction with the hereditary breast cancer associated gene product, BRCA1. FANCJ also operates in the FA pathway of interstrand cross-link repair and contributes to homologous recombination. FANCJ collaborates with a number of DNA metabolizing proteins implicated in DNA damage detection and repair, and plays an important role in cell cycle checkpoint control. In addition to its role in the classical FA pathway, FANCJ is believed to have other functions that are centered on alleviating replication stress. FANCJ resolves G-quadruplex (G4) DNA structures that are known to affect cellular replication and transcription, and potentially play a role in the preservation and functionality of chromosomal structures such as telomeres. Recent studies suggest that FANCJ helps to maintain chromatin structure and preserve epigenetic stability by facilitating smooth progression of the replication fork when it encounters DNA damage or an alternate DNA structure such as a G4. Ongoing studies suggest a prominent but still not well-understood role of FANCJ in transcriptional regulation, chromosomal structure and function, and DNA damage repair to maintain genomic stability. This review will synthesize our current understanding of the molecular and cellular functions of FANCJ that are critical for chromosomal integrity.
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Affiliation(s)
- Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health Baltimore, MD, USA
| | - Sharon B Cantor
- Department of Cancer Biology, University of Massachusetts Medical School - UMASS Memorial Cancer Center Worcester, MA, USA
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28
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León-Ortiz AM, Svendsen J, Boulton SJ. Metabolism of DNA secondary structures at the eukaryotic replication fork. DNA Repair (Amst) 2014; 19:152-62. [PMID: 24815912 DOI: 10.1016/j.dnarep.2014.03.016] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
DNA secondary structures are largely advantageous for numerous cellular processes but can pose specific threats to the progression of the replication machinery and therefore genome duplication and cell division. A number of specialized enzymes dismantle these structures to allow replication fork progression to proceed faithfully. In this review, we discuss the in vitro and in vivo data that has lead to the identification of these enzymes in eukaryotes, and the evidence that suggests that they act specifically at replication forks to resolve secondary structures. We focus on the role of helicases, which catalyze the dissociation of nucleotide complexes, and on the role of nucleases, which cleave secondary structures to allow replication fork progression at the expense of local rearrangements. Finally, we discuss outstanding questions in terms of dismantling DNA secondary structures, as well as the interplay between diverse enzymes that act upon specific types of structures.
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Affiliation(s)
- Ana María León-Ortiz
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms EN6 3LD, UK
| | - Jennifer Svendsen
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms EN6 3LD, UK
| | - Simon J Boulton
- DNA Damage Response Laboratory, London Research Institute, Cancer Research UK, Clare Hall, South Mimms EN6 3LD, UK.
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29
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Peng M, Xie J, Ucher A, Stavnezer J, Cantor SB. Crosstalk between BRCA-Fanconi anemia and mismatch repair pathways prevents MSH2-dependent aberrant DNA damage responses. EMBO J 2014; 33:1698-712. [PMID: 24966277 PMCID: PMC4194102 DOI: 10.15252/embj.201387530] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Several proteins in the BRCA-Fanconi anemia (FA) pathway, such as FANCJ, BRCA1, and FANCD2, interact with mismatch repair (MMR) pathway factors, but the significance of this link remains unknown. Unlike the BRCA-FA pathway, the MMR pathway is not essential for cells to survive toxic DNA interstrand crosslinks (ICLs), although MMR proteins bind ICLs and other DNA structures that form at stalled replication forks. We hypothesized that MMR proteins corrupt ICL repair in cells that lack crosstalk between BRCA-FA and MMR pathways. Here, we show that ICL sensitivity of cells lacking the interaction between FANCJ and the MMR protein MLH1 is suppressed by depletion of the upstream mismatch recognition factor MSH2. MSH2 depletion suppresses an aberrant DNA damage response, restores cell cycle progression, and promotes ICL resistance through a Rad18-dependent mechanism. MSH2 depletion also suppresses ICL sensitivity in cells deficient for BRCA1 or FANCD2, but not FANCA. Rescue by Msh2 loss was confirmed in Fancd2-null primary mouse cells. Thus, we propose that regulation of MSH2-dependent DNA damage response underlies the importance of interactions between BRCA-FA and MMR pathways.
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Affiliation(s)
- Min Peng
- Department of Cancer Biology, University of Massachusetts Medical School, Women's Cancers Program, UMASS Memorial Cancer Center, Worcester, MA, USA
| | - Jenny Xie
- Department of Cancer Biology, University of Massachusetts Medical School, Women's Cancers Program, UMASS Memorial Cancer Center, Worcester, MA, USA
| | - Anna Ucher
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Women's Cancers Program, UMASS Memorial Cancer Center, Worcester, MA, USA
| | - Janet Stavnezer
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Women's Cancers Program, UMASS Memorial Cancer Center, Worcester, MA, USA
| | - Sharon B Cantor
- Department of Cancer Biology, University of Massachusetts Medical School, Women's Cancers Program, UMASS Memorial Cancer Center, Worcester, MA, USA
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30
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Sommers JA, Banerjee T, Hinds T, Wan B, Wold MS, Lei M, Brosh RM. Novel function of the Fanconi anemia group J or RECQ1 helicase to disrupt protein-DNA complexes in a replication protein A-stimulated manner. J Biol Chem 2014; 289:19928-41. [PMID: 24895130 DOI: 10.1074/jbc.m113.542456] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Understanding how cellular machinery deals with chromosomal genome complexity is an important question because protein bound to DNA may affect various cellular processes of nucleic acid metabolism. DNA helicases are at the forefront of such processes, yet there is only limited knowledge how they remodel protein-DNA complexes and how these mechanisms are regulated. We have determined that representative human RecQ and Fe-S cluster DNA helicases are potently blocked by a protein-DNA interaction. The Fanconi anemia group J (FANCJ) helicase partners with the single-stranded DNA-binding protein replication protein A (RPA) to displace BamHI-E111A bound to duplex DNA in a specific manner. Protein displacement was dependent on the ATPase-driven function of the helicase and unique properties of RPA. Further biochemical studies demonstrated that the shelterin proteins TRF1 and TRF2, which preferentially bind the telomeric repeat found at chromosome ends, effectively block FANCJ from unwinding the forked duplex telomeric substrate. RPA, but not the Escherichia coli single-stranded DNA-binding protein or shelterin factor Pot1, stimulated FANCJ ejection of TRF1 from the telomeric DNA substrate. FANCJ was also able to displace TRF2 from the telomeric substrate in an RPA-dependent manner. The stimulation of helicase-catalyzed protein displacement is also observed with the DNA helicase RECQ1, suggesting a conserved functional interaction of RPA-interacting helicases. These findings suggest that partnerships between RPA and interacting human DNA helicases may greatly enhance their ability to dislodge proteins bound to duplex DNA, an activity that is likely to be highly relevant to their biological roles in DNA metabolism.
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Affiliation(s)
- Joshua A Sommers
- From the Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Taraswi Banerjee
- From the Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Twila Hinds
- From the Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224
| | - Bingbing Wan
- the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109, and
| | - Marc S Wold
- the Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, Iowa 52242
| | - Ming Lei
- the Department of Biological Chemistry, University of Michigan Medical School, Ann Arbor, Michigan 48109, and
| | - Robert M Brosh
- From the Laboratory of Molecular Gerontology, Biomedical Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224,
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31
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Gardini A, Baillat D, Cesaroni M, Shiekhattar R. Genome-wide analysis reveals a role for BRCA1 and PALB2 in transcriptional co-activation. EMBO J 2014; 33:890-905. [PMID: 24591564 DOI: 10.1002/embj.201385567] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Breast and ovarian cancer susceptibility genes BRCA1 and PALB2 have enigmatic roles in cellular growth and mammalian development. While these genes are essential for growth during early developmental programs, inactivation later in adulthood results in increased growth and formation of tumors, leading to their designation as tumor suppressors. We performed genome-wide analysis assessing their chromatin residence and gene expression responsiveness using high-throughput sequencing in breast epithelial cells. We found an intimate association between BRCA1 and PALB2 chromatin residence and genes displaying high transcriptional activity. Moreover, our experiments revealed a critical role for BRCA1 and, to a smaller degree, PALB2 in transcriptional responsiveness to NF-κB, a crucial mediator of growth and inflammatory response during development and cancer. Importantly, we also uncovered a vital role for BRCA1 and PALB2 in response to retinoic acid (RA), a growth inhibitory signal in breast cancer cells, which may constitute the basis for their tumor suppressor activity. Taken together, our results highlight an important role for these breast cancer proteins in the regulation of diverse growth regulatory pathways.
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32
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Guo M, Vidhyasagar V, Ding H, Wu Y. Insight into the roles of helicase motif Ia by characterizing Fanconi anemia group J protein (FANCJ) patient mutations. J Biol Chem 2014; 289:10551-10565. [PMID: 24573678 DOI: 10.1074/jbc.m113.538892] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Helicases are molecular motors that couple the energy of ATP hydrolysis to the unwinding and remodeling of structured DNA or RNA, which is coordinated by conserved helicase motifs. FANCJ is a DNA helicase that is genetically linked to Fanconi anemia, breast cancer, and ovarian cancer. Here, we characterized two Fanconi anemia patient mutations, R251C and Q255H, that are localized in helicase motif Ia. Our genetic complementation analysis revealed that both the R251C and Q255H alleles failed to rescue cisplatin sensitivity of a FANCJ null cell line as detected by cell survival or γ-H2AX foci formation. Furthermore, our biochemical assays demonstrated that both purified recombinant proteins abolished DNA helicase activity and failed to disrupt the DNA-protein complex. Intriguingly, R251C impaired DNA binding ability to single-strand DNA and double-strand DNA, whereas Q255H retained higher binding activity to these DNA substrates compared with wild-type FANCJ protein. Consequently, R251C abolished its DNA-dependent ATP hydrolysis activity, whereas Q255H retained normal ATPase activity. Physically, R251C had reduced ATP binding ability, whereas Q255H had normal ATP binding ability and could translocate on single-strand DNA. Although both proteins were recruited to damage sites in our laser-activated confocal assays, they lost their DNA repair function, which explains why they exerted a domain negative effect when expressed in a wild-type background. Taken together, our work not only reveals the structural function of helicase motif Ia but also provides the molecular pathology of FANCJ in related diseases.
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Affiliation(s)
- Manhong Guo
- Department of Biochemistry, University of Saskatchewan, Health Sciences Building, Saskatoon, Saskatchewan, S7N 5E5, Canada
| | - Venkatasubramanian Vidhyasagar
- Department of Biochemistry, University of Saskatchewan, Health Sciences Building, Saskatoon, Saskatchewan, S7N 5E5, Canada
| | - Hao Ding
- Department of Biochemistry, University of Saskatchewan, Health Sciences Building, Saskatoon, Saskatchewan, S7N 5E5, Canada
| | - Yuliang Wu
- Department of Biochemistry, University of Saskatchewan, Health Sciences Building, Saskatoon, Saskatchewan, S7N 5E5, Canada.
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Bharti SK, Sommers JA, George F, Kuper J, Hamon F, Shin-ya K, Teulade-Fichou MP, Kisker C, Brosh RM. Specialization among iron-sulfur cluster helicases to resolve G-quadruplex DNA structures that threaten genomic stability. J Biol Chem 2013; 288:28217-29. [PMID: 23935105 DOI: 10.1074/jbc.m113.496463] [Citation(s) in RCA: 103] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G-quadruplex (G4) DNA, an alternate structure formed by Hoogsteen hydrogen bonds between guanines in G-rich sequences, threatens genomic stability by perturbing normal DNA transactions including replication, repair, and transcription. A variety of G4 topologies (intra- and intermolecular) can form in vitro, but the molecular architecture and cellular factors influencing G4 landscape in vivo are not clear. Helicases that unwind structured DNA molecules are emerging as an important class of G4-resolving enzymes. The BRCA1-associated FANCJ helicase is among those helicases able to unwind G4 DNA in vitro, and FANCJ mutations are associated with breast cancer and linked to Fanconi anemia. FANCJ belongs to a conserved iron-sulfur (Fe S) cluster family of helicases important for genomic stability including XPD (nucleotide excision repair), DDX11 (sister chromatid cohesion), and RTEL (telomere metabolism), genetically linked to xeroderma pigmentosum/Cockayne syndrome, Warsaw breakage syndrome, and dyskeratosis congenita, respectively. To elucidate the role of FANCJ in genomic stability, its molecular functions in G4 metabolism were examined. FANCJ efficiently unwound in a kinetic and ATPase-dependent manner entropically favored unimolecular G4 DNA, whereas other Fe-S helicases tested did not. The G4-specific ligands Phen-DC3 or Phen-DC6 inhibited FANCJ helicase on unimolecular G4 ∼1000-fold better than bi- or tetramolecular G4 DNA. The G4 ligand telomestatin induced DNA damage in human cells deficient in FANCJ but not DDX11 or XPD. These findings suggest FANCJ is a specialized Fe-S cluster helicase that preserves chromosomal stability by unwinding unimolecular G4 DNA likely to form in transiently unwound single-stranded genomic regions.
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Affiliation(s)
- Sanjay Kumar Bharti
- From the Laboratory of Molecular Gerontology, NIA, National Institutes of Health, National Institutes of Health Biomedical Research Center, Baltimore, Maryland 21224
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Abstract
Helicases have major roles in genome maintenance by unwinding structured nucleic acids. Their prominence is marked by various cancers and genetic disorders that are linked to helicase defects. Although considerable effort has been made to understand the functions of DNA helicases that are important for genomic stability and cellular homeostasis, the complexity of the DNA damage response leaves us with unanswered questions regarding how helicase-dependent DNA repair pathways are regulated and coordinated with cell cycle checkpoints. Further studies may open the door to targeting helicases in order to improve cancer treatments based on DNA-damaging chemotherapy or radiation.
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Affiliation(s)
- Robert M Brosh
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, 251 Bayview Boulevard, Baltimore, Maryland 21224, USA.
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35
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Abstract
Mutations of the breast and ovarian cancer susceptibility gene 1 (BRCA1) account for about 40-45% of hereditary breast cancer cases. Moreover, a significant fraction of sporadic (non-hereditary) breast and ovarian cancers exhibit reduced or absent expression of the BRCA1 protein, suggesting an additional role for BRCA1 in sporadic cancers. BRCA1 follows the classic pattern of a highly penetrant Knudsen-type tumor suppressor gene in which one allele is inactivated through a germ-line mutation and the other is mutated or deleted within the tumor. BRCA1 is a multi-functional protein but it is not fully understood which function(s) is (are) most important for tumor suppression, nor is it clear why BRCA1-mutations confer a high risk for breast and ovarian cancers and not a broad spectrum of tumor types. Here, we will review BRCA1 functions in the DNA damage response (DDR), which are likely to contribute to tumor suppression. In the process, we will highlight some of the controversies and unresolved issues in the field. We will also describe a recently identified and under-investigated role for BRCA1 in the regulation of telomeres and the implications of this role in the DDR and cancer suppression.
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Affiliation(s)
- Eliot M Rosen
- Department of Oncology, Georgetown University School of Medicine Washington, DC, USA ; Department of Biochemistry, Molecular and Cellular Biology, Georgetown University School of Medicine Washington, DC, USA ; Department of Radiation Medicine, Georgetown University School of Medicine Washington, DC, USA
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BRIP1 variations analysis reveals their relative importance as genetic susceptibility factor for cervical cancer. Biochem Biophys Res Commun 2013; 433:232-6. [DOI: 10.1016/j.bbrc.2013.02.089] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Accepted: 02/27/2013] [Indexed: 12/24/2022]
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Schwab RA, Nieminuszczy J, Shin-ya K, Niedzwiedz W. FANCJ couples replication past natural fork barriers with maintenance of chromatin structure. J Cell Biol 2013; 201:33-48. [PMID: 23530069 PMCID: PMC3613694 DOI: 10.1083/jcb.201208009] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 02/26/2013] [Indexed: 11/22/2022] Open
Abstract
Defective DNA repair causes Fanconi anemia (FA), a rare childhood cancer-predisposing syndrome. At least 15 genes are known to be mutated in FA; however, their role in DNA repair remains unclear. Here, we show that the FANCJ helicase promotes DNA replication in trans by counteracting fork stalling on replication barriers, such as G4 quadruplex structures. Accordingly, stabilization of G4 quadruplexes in ΔFANCJ cells restricts fork movements, uncouples leading- and lagging-strand synthesis and generates small single-stranded DNA gaps behind the fork. Unexpectedly, we also discovered that FANCJ suppresses heterochromatin spreading by coupling fork movement through replication barriers with maintenance of chromatin structure. We propose that FANCJ plays an essential role in counteracting chromatin compaction associated with unscheduled replication fork stalling and restart, and suppresses tumorigenesis, at least partially, in this replication-specific manner.
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Affiliation(s)
- Rebekka A. Schwab
- The Weatherall Institute of Molecular Medicine, Oxford University, Oxford OX3 9DS, England, UK
| | - Jadwiga Nieminuszczy
- The Weatherall Institute of Molecular Medicine, Oxford University, Oxford OX3 9DS, England, UK
- Institute of Biochemistry and Biophysics, PAS, 02-106 Warsaw, Poland
| | - Kazuo Shin-ya
- Biomedicinal Information Research Center, National Institute of Advanced Industrial Science and Technology, Koto-ku, Tokyo 135-0064, Japan
| | - Wojciech Niedzwiedz
- The Weatherall Institute of Molecular Medicine, Oxford University, Oxford OX3 9DS, England, UK
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Abstract
The breast cancer type 1 susceptibility protein (BRCA1) is involved in several important cellular pathways, including DNA damage repair, chromatin remodeling and checkpoint activation. The BRCA1 tumor suppression function has been attributed to its role in homologous recombination damage repair. In this review, historical facts concerning BRCA1, together with recent research advances regarding our understanding of the BRCA1 interacting proteins that are involved in, homologous recombination (HR) double strand break (DBS) repair and how these interacting proteins maintain chromosomal integrity, are discussed. In addition, this review poses the questions as to what extent HR repair cannot be properly fulfilled when breast cancer related mutations in the BRCA1 gene occur and how the recent and excessive studied poly-ADP ribose polymerase (PARP) inhibiting therapy approach links with the proposed tumor suppression function of the different BRCA1 domains.
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Affiliation(s)
- Kevin W Caestecker
- Department of Comparative Physiology and Biometrics, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
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Sakasai R, Sakai A, Iimori M, Kiyonari S, Matsuoka K, Kakeji Y, Kitao H, Maehara Y. CtIP- and ATR-dependent FANCJ phosphorylation in response to DNA strand breaks mediated by DNA replication. Genes Cells 2012; 17:962-70. [PMID: 23157317 DOI: 10.1111/gtc.12011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Accepted: 09/25/2012] [Indexed: 11/30/2022]
Abstract
FANCJ, also called BACH1/BRIP1, is a 5'-3' DEAH helicase, whose mutations are known as a risk factor for Fanconi anemia and also breast and ovarian cancer. FANCJ is thought to contribute to DNA double-strand break (DSB) repair and S-phase checkpoint through binding to multiple partner proteins, such as BRCA1 and TopBP1, but its molecular regulation remains unclear. We focused on DNA damage-induced phosphorylation of FANCJ and found that reagents that cause DSB or replication fork stalling induce FANCJ hyperphosphorylation. In particular, camptothecin (CPT) induced rapid and efficient FANCJ hyperphosphorylation that was largely dependent on TopBP1 and ATM-Rad3 related (ATR) kinase. Furthermore, DNA end resection that exposes single-strand DNA at the DSB site was required for hyperphosphorylation. Interestingly, upon CPT treatment, a dramatic increase in the FANCJ-TopBP1 complex was observed, and this increase was not alleviated even when ATR-dependent hyperphosphorylation was suppressed. These results suggest that FANCJ function may be modulated by hyperphosphorylation in a DNA end resection- and ATR-dependent manner and by FANCJ-TopBP1 complex formation in response to replication-coupled DSBs.
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Affiliation(s)
- Ryo Sakasai
- Innovative Anticancer Strategy for Therapeutics and Diagnosis Group, Innovation Center for Medical Redox Navigation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
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40
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Tu Z, Aird KM, Zhang R. RAS, cellular senescence and transformation: the BRCA1 DNA repair pathway at the crossroads. Small GTPases 2012; 3:163-7. [PMID: 22751483 DOI: 10.4161/sgtp.19884] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The definition of an oncogene is a gene that actively promotes tumorigenesis. For example, activation of RAS oncogene promotes cell transformation and cancer. Paradoxically, in primary mammalian cells, oncogenic RAS typically triggers cellular senescence, a state of irreversible cell growth arrest. Oncogene-induced senescence is an important tumor suppression mechanism in vivo. Here, we discuss our recent evidence that RAS-induced suppression of DNA repair response via dissociation of BRCA1 from chromatin promotes senescence while predisposing cells to senescence bypass and transformation by allowing for secondary hits. The molecular mechanism we uncovered helps reconcile the tumor-promoting nature of oncogenic RAS with the tumor-suppressing role of oncogene-induced senescence.
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Affiliation(s)
- Zhigang Tu
- Women's Cancer Program and Epigenetics and Progenitor Cell Keystone Program, Fox Chase Cancer Center, Philadelphia, PA, USA
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41
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Thompson LH. Recognition, signaling, and repair of DNA double-strand breaks produced by ionizing radiation in mammalian cells: the molecular choreography. Mutat Res 2012; 751:158-246. [PMID: 22743550 DOI: 10.1016/j.mrrev.2012.06.002] [Citation(s) in RCA: 261] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2011] [Revised: 06/09/2012] [Accepted: 06/16/2012] [Indexed: 12/15/2022]
Abstract
The faithful maintenance of chromosome continuity in human cells during DNA replication and repair is critical for preventing the conversion of normal diploid cells to an oncogenic state. The evolution of higher eukaryotic cells endowed them with a large genetic investment in the molecular machinery that ensures chromosome stability. In mammalian and other vertebrate cells, the elimination of double-strand breaks with minimal nucleotide sequence change involves the spatiotemporal orchestration of a seemingly endless number of proteins ranging in their action from the nucleotide level to nucleosome organization and chromosome architecture. DNA DSBs trigger a myriad of post-translational modifications that alter catalytic activities and the specificity of protein interactions: phosphorylation, acetylation, methylation, ubiquitylation, and SUMOylation, followed by the reversal of these changes as repair is completed. "Superfluous" protein recruitment to damage sites, functional redundancy, and alternative pathways ensure that DSB repair is extremely efficient, both quantitatively and qualitatively. This review strives to integrate the information about the molecular mechanisms of DSB repair that has emerged over the last two decades with a focus on DSBs produced by the prototype agent ionizing radiation (IR). The exponential growth of molecular studies, heavily driven by RNA knockdown technology, now reveals an outline of how many key protein players in genome stability and cancer biology perform their interwoven tasks, e.g. ATM, ATR, DNA-PK, Chk1, Chk2, PARP1/2/3, 53BP1, BRCA1, BRCA2, BLM, RAD51, and the MRE11-RAD50-NBS1 complex. Thus, the nature of the intricate coordination of repair processes with cell cycle progression is becoming apparent. This review also links molecular abnormalities to cellular pathology as much a possible and provides a framework of temporal relationships.
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Affiliation(s)
- Larry H Thompson
- Biology & Biotechnology Division, L452, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94551-0808, United States.
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Wu Y, Sommers JA, Loiland JA, Kitao H, Kuper J, Kisker C, Brosh RM. The Q motif of Fanconi anemia group J protein (FANCJ) DNA helicase regulates its dimerization, DNA binding, and DNA repair function. J Biol Chem 2012; 287:21699-716. [PMID: 22582397 DOI: 10.1074/jbc.m112.351338] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The Q motif, conserved in a number of RNA and DNA helicases, is proposed to be important for ATP binding based on structural data, but its precise biochemical functions are less certain. FANCJ encodes a Q motif DEAH box DNA helicase implicated in Fanconi anemia and breast cancer. A Q25A mutation of the invariant glutamine in the Q motif abolished its ability to complement cisplatin or telomestatin sensitivity of a fancj null cell line and exerted a dominant negative effect. Biochemical characterization of the purified recombinant FANCJ-Q25A protein showed that the mutation disabled FANCJ helicase activity and the ability to disrupt protein-DNA interactions. FANCJ-Q25A showed impaired DNA binding and ATPase activity but displayed ATP binding and temperature-induced unfolding transition similar to FANCJ-WT. Size exclusion chromatography and sedimentation velocity analyses revealed that FANCJ-WT existed as molecular weight species corresponding to a monomer and a dimer, and the dimeric form displayed a higher specific activity for ATPase and helicase, as well as greater DNA binding. In contrast, FANCJ-Q25A existed only as a monomer, devoid of helicase activity. Thus, the Q motif is essential for FANCJ enzymatic activity in vitro and DNA repair function in vivo.
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Affiliation(s)
- Yuliang Wu
- Laboratory of Molecular Gerontology, National Institutes of Health Biomedical Research Center, NIA, Baltimore, Maryland 21224, USA
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BRCA1-mediated repression of mutagenic end-joining of DNA double-strand breaks requires complex formation with BACH1. Biochem J 2012; 441:919-26. [PMID: 22032289 DOI: 10.1042/bj20110314] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
BACH1 (BRCA1-associated C-terminal helicase 1), the product of the BRIP1 {BRCA1 [breast cancer 1, early onset]-interacting protein C-terminal helicase 1; also known as FANCJ [FA-J (Fanconi anaemia group J) protein]} gene mutated in Fanconi anaemia patients from complementation group J, has been implicated in DNA repair and damage signalling. BACH1 exerts DNA helicase activities and physically interacts with BRCA1 and MLH1 (mutL homologue 1), which differentially control DNA DSB (double-strand break) repair processes. The present study shows that BACH1 plays a role in both HR (homologous recombination) and MMEJ (microhomology-mediated non-homologous end-joining) and reveals discrete mechanisms underlying modulation of these pathways. Our results indicate that BACH1 stimulates HR, which depends on the integrity of the helicase domain. Disruption of the BRCA1-BACH1 complex through mutation of BACH1 compromised errorfree NHEJ (non-homologous end-joining) and accelerated error-prone MMEJ. Conversely, molecular changes in BACH1 abrogating MLH1 binding interfered neither with HR nor with MMEJ. Importantly, MMEJ is a mutagenic DSB repair pathway, which is derepressed in hereditary breast and ovarian carcinomas. Since BRCA1 and BACH1 mutations targeting the BRCA1-BACH1 interaction have been associated with breast cancer susceptibility, the results of the present study thus provide evidence for a novel role of BACH1 in tumour suppression.
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Wang B. BRCA1 tumor suppressor network: focusing on its tail. Cell Biosci 2012; 2:6. [PMID: 22369660 PMCID: PMC3315748 DOI: 10.1186/2045-3701-2-6] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 02/27/2012] [Indexed: 02/07/2023] Open
Abstract
Germline mutations of the BRCA1 tumor suppressor gene are a major cause of familial breast and ovarian cancer. BRCA1 plays critical roles in the DNA damage response that regulates activities of multiple repair and checkpoint pathways for maintaining genome stability. The BRCT domains of BRCA1 constitute a phospho-peptide binding domain recognizing a phospho-SPxF motif (S, serine; P, proline; × varies; F, phenylalanine). The BRCT domains are frequently targeted by clinically important mutations and most of these mutations disrupt the binding surface of the BRCT domains to phosphorylated peptides. The BRCT domain and its capability to bind phosphorylated protein is required for the tumor suppressor function of BRCA1. Through its BRCT phospho-binding ability BRCA1 forms at least three mutually exclusive complexes by binding to phosphorylated proteins Abraxas, Bach1 and CTIP. The A, B and C complexes, at lease partially undertake BRCA1's role in mechanisms of cell cycle checkpoint and DNA repair that maintain genome stability, thus may play important roles in BRCA1's tumor suppressor function.
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Affiliation(s)
- Bin Wang
- Department of Genetics, The University of Texas M,D, Anderson Cancer Center, 1515 Holcombe Blvd, Unit 1010, Houston, TX 77030, USA.
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45
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Dever SM, White ER, Hartman MCT, Valerie K. BRCA1-directed, enhanced and aberrant homologous recombination: mechanism and potential treatment strategies. Cell Cycle 2012; 11:687-94. [PMID: 22306997 DOI: 10.4161/cc.11.4.19212] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Despite intense studies, questions still remain regarding the molecular mechanisms leading to the development of hereditary breast and ovarian cancers. Research focused on elucidating the role of the breast cancer susceptibility gene 1 (BRCA1) in the DNA damage response may be of the most critical importance to understanding these processes. The BRCA1 protein has an N-terminal RING domain possessing E3 ubiquitinligase activity and a C-terminal BRCT domain involved in binding specific phosphoproteins. These domains are involved directly or indirectly in DNA double-strand break (DSB) repair. As the two terminal domains of BRCA1 represent two separate entities, understanding how these domains communicate and are functionally altered in regards to DSB repair is critical for understanding the development of BRCA1-related breast and ovarian cancers and for developing novel therapeutics. Herein, we review recent findings of how altered functions of these domains might lead to cancer through a mechanism of increased aberrant homologous recombination and possible implications for the development of BRCA1 inhibitors.
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Affiliation(s)
- Seth M Dever
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, VA, USA
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Wu Y, Brosh RM. DNA helicase and helicase-nuclease enzymes with a conserved iron-sulfur cluster. Nucleic Acids Res 2012; 40:4247-60. [PMID: 22287629 PMCID: PMC3378879 DOI: 10.1093/nar/gks039] [Citation(s) in RCA: 110] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Conserved Iron-Sulfur (Fe-S) clusters are found in a growing family of metalloproteins that are implicated in prokaryotic and eukaryotic DNA replication and repair. Among these are DNA helicase and helicase-nuclease enzymes that preserve chromosomal stability and are genetically linked to diseases characterized by DNA repair defects and/or a poor response to replication stress. Insight to the structural and functional importance of the conserved Fe-S domain in DNA helicases has been gleaned from structural studies of the purified proteins and characterization of Fe-S cluster site-directed mutants. In this review, we will provide a current perspective of what is known about the Fe-S cluster helicases, with an emphasis on how the conserved redox active domain may facilitate mechanistic aspects of helicase function. We will discuss testable models for how the conserved Fe-S cluster might operate in helicase and helicase-nuclease enzymes to conduct their specialized functions that help to preserve the integrity of the genome.
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Affiliation(s)
- Yuliang Wu
- Department of Biochemistry, University of Saskatchewan, Health Sciences Building, Saskatoon, Saskatchewan, S7N 5E5, Canada.
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47
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Tu Z, Aird KM, Bitler BG, Nicodemus JP, Beeharry N, Xia B, Yen TJ, Zhang R. Oncogenic RAS regulates BRIP1 expression to induce dissociation of BRCA1 from chromatin, inhibit DNA repair, and promote senescence. Dev Cell 2011; 21:1077-91. [PMID: 22137763 DOI: 10.1016/j.devcel.2011.10.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 06/29/2011] [Accepted: 10/11/2011] [Indexed: 12/16/2022]
Abstract
Here, we report a cell-intrinsic mechanism by which oncogenic RAS promotes senescence while predisposing cells to senescence bypass by allowing for secondary hits. We show that oncogenic RAS inactivates the BRCA1 DNA repair complex by dissociating BRCA1 from chromatin. This event precedes senescence-associated cell cycle exit and coincides with the accumulation of DNA damage. Downregulation of BRIP1, a physiological partner of BRCA1 in the DNA repair pathway, triggers BRCA1 chromatin dissociation. Conversely, ectopic BRIP1 rescues BRCA1 chromatin dissociation and suppresses RAS-induced senescence and the DNA damage response. Significantly, cells undergoing senescence do not exhibit a BRCA1-dependent DNA repair response when exposed to DNA damage. Overall, our study provides a molecular basis by which oncogenic RAS promotes senescence. Because DNA damage has the potential to produce additional "hits" that promote senescence bypass, our findings may also suggest one way a small minority of cells might bypass senescence and contribute to cancer development.
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Affiliation(s)
- Zhigang Tu
- Women's Cancer Program, Fox Chase Cancer Center, 333 Cottman Avenue, Philadelphia, PA 19111, USA
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48
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Wang W, Corrigan-Cummins M, Hudson J, Maric I, Simakova O, Neelapu SS, Kwak LW, Janik JE, Gause B, Jaffe ES, Calvo KR. MicroRNA profiling of follicular lymphoma identifies microRNAs related to cell proliferation and tumor response. Haematologica 2011; 97:586-94. [PMID: 22102710 DOI: 10.3324/haematol.2011.048132] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND MicroRNAs can play an important role in tumorigenesis through post-transcriptional regulation of gene expression, and are not well characterized in follicular lymphoma. DESIGN AND METHODS MicroRNA profiles of enriched follicular lymphoma tumor cells from 16 patients were generated by assaying 851 human microRNAs. Tandem gene expression profiles were obtained for predicting microRNA targets. RESULTS The expression of 133 microRNAs was significantly different (> 2-fold; P<0.05) between follicular lymphoma and follicular hyperplasia. Forty-four microRNAs in three groups generated a unique follicular lymphoma signature. Of these, ten microRNAs were increased (miR-193a-5p, -193b*, -345, -513b, -574-3p, -584, -663, -1287, -1295, and -1471), 11 microRNAs were decreased (miR-17*, -30a, -33a, -106a*, -141, -202, -205, -222, -301b, -431*, and -570), and 23 microRNAs formed a group that was increased in most cases of follicular lymphoma but showed lower expression in a subset of cases (let-7a, let-7f, miR-7-1*, -9, -9*, -20a, -20b, -30b, -96, -98, -194, -195, -221*, -374a, -374b, -451, -454, -502-3p, -532-3p, -664*, -1274a, -1274b, and -1260). Higher expression of this last group was associated with improved response to chemotherapy. Gene expression analysis revealed increased expression of MAPK1, AKT1, PRKCE, IL4R and DROSHA and decreased expression of CDKN1A/p21, SOCS2, CHEK1, RAD51, KLF4, BLIMP1 and IRF4 in follicular lymphoma. Functional studies indicated that CDKN1A/p21 and SOCS2 expression is directly regulated by miR-20a/-20b and miR-194, respectively. CONCLUSIONS Follicular lymphoma is characterized by a unique microRNA signature, containing a subset of microRNAs whose expression correlate with response to chemotherapy. miR-20a/b and miR-194 target CDKN1A and SOCS2 in follicular lymphoma, potentially contributing to tumor cell proliferation and survival.
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Affiliation(s)
- Weixin Wang
- Department of Laboratory Medicine, Hematology Section NIH Clinical Center, 10 Center Dr, Bldg 10/2C306 Bethesda, 20892-1508, USA
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Mutations in BRIP1 confer high risk of ovarian cancer. Nat Genet 2011; 43:1104-7. [PMID: 21964575 DOI: 10.1038/ng.955] [Citation(s) in RCA: 279] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 09/02/2011] [Indexed: 12/12/2022]
Abstract
Ovarian cancer causes more deaths than any other gynecologic malignancy in developed countries. Sixteen million sequence variants, identified through whole-genome sequencing of 457 Icelanders, were imputed to 41,675 Icelanders genotyped using SNP chips, as well as to their relatives. Sequence variants were tested for association with ovarian cancer (N of affected individuals = 656). We discovered a rare (0.41% allelic frequency) frameshift mutation, c.2040_2041insTT, in the BRIP1 (FANCJ) gene that confers an increase in ovarian cancer risk (odds ratio (OR) = 8.13, P = 2.8 × 10(-14)). The mutation was also associated with increased risk of cancer in general and reduced lifespan by 3.6 years. In a Spanish population, another frameshift mutation in BRIP1, c.1702_1703del, was seen in 2 out of 144 subjects with ovarian cancer and 1 out of 1,780 control subjects (P = 0.016). This allele was also associated with breast cancer (seen in 6/927 cases; P = 0.0079). Ovarian tumors from heterozygous carriers of the Icelandic mutation show loss of the wild-type allele, indicating that BRIP1 behaves like a classical tumor suppressor gene in ovarian cancer.
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Dever SM, Golding SE, Rosenberg E, Adams BR, Idowu MO, Quillin JM, Valerie N, Xu B, Povirk LF, Valerie K. Mutations in the BRCT binding site of BRCA1 result in hyper-recombination. Aging (Albany NY) 2011; 3:515-32. [PMID: 21666281 PMCID: PMC3156602 DOI: 10.18632/aging.100325] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We introduced a K1702M mutation in the BRCA1 BRCT domain known to prevent the binding of proteins harboring pS-X-X-F motifs such as Abraxas-RAP80, BRIP1, and CtIP. Surprisingly, rather than impairing homologous recombination repair (HRR), expression of K1702M resulted in hyper-recombination coinciding with an accumulation of cells in S-G2 and no effect on nonhomologous end-joining. These cells also showed increased RAD51 and RPA nuclear staining. More pronounced effects were seen with a naturally occurring BRCT mutant (M1775R) that also produced elevated levels of ssDNA, in part co-localizing with RPA, in line with excessive DNA resection. M1775R induced unusual, thread-like promyelocytic leukemia (PML) nuclear bodies and clustered RPA foci rather than the typical juxtaposed RPA-PML foci seen with wild-type BRCA1. Interestingly, K1702M hyper-recombination diminished with a second mutation in the BRCA1 RING domain (I26A) known to reduce BRCA1 ubiquitin-ligase activity. Thesein vitro findings correlated with elevated nuclear RAD51 and RPA staining of breast cancer tissue from a patient with the M1775R mutation. Altogether, the disruption of BRCA1 (BRCT)-pS-X-X-F protein binding results in ubiquitination-dependent hyper-recombination via excessive DNA resection and the appearance of atypical PML-NBs. Thus, certain BRCA1 mutations that cause hyper-recombination instead of reduced DSB repair might lead to breast cancer.
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Affiliation(s)
- Seth M Dever
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, 23298, USA
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