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Tsubouchi H. The Hop2-Mnd1 Complex and Its Regulation of Homologous Recombination. Biomolecules 2023; 13:biom13040662. [PMID: 37189409 DOI: 10.3390/biom13040662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 04/06/2023] [Accepted: 04/07/2023] [Indexed: 05/17/2023] Open
Abstract
Homologous recombination (HR) is essential for meiosis in most sexually reproducing organisms, where it is induced upon entry into meiotic prophase. Meiotic HR is conducted by the collaborative effort of proteins responsible for DNA double-strand break repair and those produced specifically during meiosis. The Hop2-Mnd1 complex was originally identified as a meiosis-specific factor that is indispensable for successful meiosis in budding yeast. Later, it was found that Hop2-Mnd1 is conserved from yeasts to humans, playing essential roles in meiosis. Accumulating evidence suggests that Hop2-Mnd1 promotes RecA-like recombinases towards homology search/strand exchange. This review summarizes studies on the mechanism of the Hop2-Mnd1 complex in promoting HR and beyond.
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Affiliation(s)
- Hideo Tsubouchi
- Institute of Innovative Research, Tokyo Institute of Technology, Yokohama 226-8503, Kanagawa, Japan
- School of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8503, Kanagawa, Japan
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2
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Lingg L, Rottenberg S, Francica P. Meiotic Genes and DNA Double Strand Break Repair in Cancer. Front Genet 2022; 13:831620. [PMID: 35251135 PMCID: PMC8895043 DOI: 10.3389/fgene.2022.831620] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Accepted: 02/02/2022] [Indexed: 12/16/2022] Open
Abstract
Tumor cells show widespread genetic alterations that change the expression of genes driving tumor progression, including genes that maintain genomic integrity. In recent years, it has become clear that tumors frequently reactivate genes whose expression is typically restricted to germ cells. As germ cells have specialized pathways to facilitate the exchange of genetic information between homologous chromosomes, their aberrant regulation influences how cancer cells repair DNA double strand breaks (DSB). This drives genomic instability and affects the response of tumor cells to anticancer therapies. Since meiotic genes are usually transcriptionally repressed in somatic cells of healthy tissues, targeting aberrantly expressed meiotic genes may provide a unique opportunity to specifically kill cancer cells whilst sparing the non-transformed somatic cells. In this review, we highlight meiotic genes that have been reported to affect DSB repair in cancers derived from somatic cells. A better understanding of their mechanistic role in the context of homology-directed DNA repair in somatic cancers may provide useful insights to find novel vulnerabilities that can be targeted.
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Affiliation(s)
- Lea Lingg
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Cancer Therapy Resistance Cluster, Department for BioMedical Research, University of Bern, Bern, Switzerland
| | - Sven Rottenberg
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Cancer Therapy Resistance Cluster, Department for BioMedical Research, University of Bern, Bern, Switzerland
- Bern Center for Precision Medicine, University of Bern, Bern, Switzerland
- *Correspondence: Sven Rottenberg, ; Paola Francica,
| | - Paola Francica
- Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Bern, Switzerland
- Cancer Therapy Resistance Cluster, Department for BioMedical Research, University of Bern, Bern, Switzerland
- *Correspondence: Sven Rottenberg, ; Paola Francica,
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3
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Lin T, Zhang Y, Zhang T, Steckler RA, Yang X. Hop2 interacts with the transcription factor CEBPα and suppresses adipocyte differentiation. J Biol Chem 2021; 297:101264. [PMID: 34600885 PMCID: PMC8528721 DOI: 10.1016/j.jbc.2021.101264] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 09/09/2021] [Accepted: 09/28/2021] [Indexed: 11/16/2022] Open
Abstract
CCAAT enhancer binding protein (CEBP) transcription factors (TFs) are known to promote adipocyte differentiation; however, suppressors of CEBP TFs have not been reported thus far. Here, we find that homologous chromosome pairing protein 2 (Hop2) functions as an inhibitor for the TF CEBPα. We found that Hop2 mRNA is highly and specifically expressed in adipose tissue, and that ectopic Hop2 expression suppresses reporter activity induced by CEBP as revealed by DNA transfection. Recombinant and ectopically expressed Hop2 was shown to interact with CEBPα in pull-down and coimmunoprecipitation assays, and interaction between endogenous Hop2 and CEBPα was observed in the nuclei of 3T3 preadipocytes and adipocytes by immunofluorescence and coimmunoprecipitation of nuclear extracts. In addition, Hop2 stable overexpression in 3T3 preadipocytes inhibited adipocyte differentiation and adipocyte marker gene expression. These in vitro data suggest that Hop2 inhibits adipogenesis by suppressing CEBP-mediated transactivation. Consistent with a negative role for Hop2 in adipogenesis, ablation of Hop2 (Hop2-/-) in mice led to increased body weight, adipose volume, adipocyte size, and adipogenic marker gene expression. Adipogenic differentiation of isolated adipose-derived mesenchymal stem cells showed a greater number of lipid droplet-containing colonies formed in Hop2-/- adipose-derived mesenchymal stem cell cultures than in wt controls, which is associated with the increased expression of adipogenic marker genes. Finally, chromatin immunoprecipitation revealed a higher binding activity of endogenous CEBPα to peroxisome proliferator-activated receptor γ, a master adipogenic TF, and a known CEBPα target gene. Therefore, our study identifies for the first time that Hop2 is an intrinsic suppressor of CEBPα and thus adipogenesis in adipocytes.
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Affiliation(s)
- Tonghui Lin
- Department of Pediatrics, Pediatric Research Center, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas, USA
| | - Yang Zhang
- Department of Pediatrics, Pediatric Research Center, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas, USA
| | - Tingting Zhang
- Department of Pediatrics, Pediatric Research Center, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas, USA
| | - Rita A Steckler
- Department of Pediatrics, Pediatric Research Center, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas, USA
| | - Xiangli Yang
- Department of Pediatrics, Pediatric Research Center, University of Texas Health Science Center at Houston, McGovern Medical School, Houston, Texas, USA.
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4
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Genetic network and gene set enrichment analyses identify MND1 as potential diagnostic and therapeutic target gene for lung adenocarcinoma. Sci Rep 2021; 11:9430. [PMID: 33941804 PMCID: PMC8093199 DOI: 10.1038/s41598-021-88948-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 04/15/2021] [Indexed: 01/22/2023] Open
Abstract
This study aimed to characterize the key survival-specific genes for lung adenocarcinoma (LUAD) using machine-based learning approaches. Gene expression profiles were download from gene expression omnibus to analyze differentially expressed genes (DEGs) in LUAD tissues versus healthy lung tissue and to construct protein–protein interaction (PPI) networks. Using high-dimensional datasets of cancer specimens from clinical patients in the cancer genome atlas, gene set enrichment analysis was employed to assess the independent effect of meiotic nuclear divisions 1 (MND1) expression on survival status, and univariate and multivariate Cox regression analyses were applied to determine the associations of clinic-pathologic characteristics and MND1 expression with overall survival (OS). A set of 495 DEGs (145 upregulated and 350 downregulated) was detected, including 63 hub genes with ≥ 10 nodes in the PPI network. Among them, MND1 was participated in several important pathways by connecting with other genes via 17 nodes in lung cancer, and more frequently expressed in LUAD patients with advancing stage (OR = 1.68 for stage III vs. stage I). Univariate and multivariate Cox analyses demonstrated that the expression level of MND1 was significantly and negatively correlated with OS. Therefore, MND1 is a promising diagnostic and therapeutic target for LUAD.
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5
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Pang J, Gao J, Zhang L, Mivechi NF, Ko L. GT198 Is a Target of Oncology Drugs and Anticancer Herbs. FRONTIERS IN ORAL HEALTH 2020; 2. [PMID: 34476412 PMCID: PMC8409151 DOI: 10.3389/froh.2021.679460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Tumor angiogenesis is a hallmark of cancer. Therapeutic drug inhibitors targeting angiogenesis are clinically effective. We have previously identified GT198 (gene symbol PSMC3IP, also known as Hop2) as an oncoprotein that induces tumor angiogenesis in human cancers, including oral cancer. In this study, we show that the GT198 protein is a direct drug target of more than a dozen oncology drugs and several clinically successful anticancer herbs. GT198 is a DNA repair protein that binds to DNA. Using an in vitro DNA-binding assay, we tested the approved oncology drug set VII from the National Cancer Institute containing 129 oncology drugs. Identified GT198 inhibitors include but are not limited to mitoxantrone, doxorubicin, paclitaxel, etoposide, dactinomycin, and imatinib. Paclitaxel and etoposide have higher binding affinities, whereas doxorubicin has higher binding efficacy due to competitive inhibition. GT198 shares protein sequence homology with DNA topoisomerases, which are known drug targets, so that GT198 is likely a new drug target previously unrecognized. To seek more powerful GT198 inhibitors, we further tested several anticancer herbal extracts. The positive anticancer herbs with high affinity and high efficacy are all clinically successful ones, including allspice from Jamaica, Gleditsia sinensis or honey locust from China, and BIRM from Ecuador. Partial purification of allspice using an organic chemical approach demonstrated great feasibility of natural product purification, when the activity is monitored by the in vitro DNA-binding assay using GT198 as a target. Together, our study reveals GT198 as a new targeting mechanism for existing oncology drugs. The study also delivers an excellent drug target suitable for compound identification and natural product purification. In particular, this study opens an opportunity to rapidly identify drugs with high efficacy and low toxicity from nature.
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Affiliation(s)
- Junfeng Pang
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Jie Gao
- Department of Clinical and Diagnostic Science, The University of Alabama at Birmingham, Birmingham, AL, United States
| | - Liyong Zhang
- Department of Surgery, University of Pittsburgh, Pittsburgh, PA, United States
| | - Nahid F Mivechi
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, United States
| | - Lan Ko
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, United States.,Research and Development, OnkoTarget, Augusta, GA, United States
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Achyut BR, Zhang H, Angara K, Mivechi NF, Arbab AS, Ko L. Oncoprotein GT198 vaccination delays tumor growth in MMTV-PyMT mice. Cancer Lett 2020; 476:57-66. [PMID: 32061755 PMCID: PMC7067666 DOI: 10.1016/j.canlet.2020.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 12/29/2019] [Accepted: 02/07/2020] [Indexed: 02/05/2023]
Abstract
Targeting early lesion in breast cancer is more therapeutically effective. We have previously identified an oncoprotein GT198 (PSMC3IP) in human breast cancer. Here we investigated GT198 in MMTV-PyMT mouse mammary gland tumors and found that GT198 is a shared early lesion in both species. Similar to human breast cancer even before a tumor appears, cytoplasmic GT198 is overexpressed in mouse tumor stroma including pericyte stem cells, descendent adipocytes, fibroblasts, and myoepithelial cells. Using recombinant GT198 protein as an antigen, we vaccinated MMTV-PyMT mice and found that the GT198 vaccine delayed mouse tumor growth and reduced lung metastasis. The antitumor effects were linearly correlated with vaccinated mouse serum titers of GT198 antibody, which recognized cell surface GT198 protein on viable tumor cells confirmed by FACS. Furthermore, GT198+ tumor cells isolated from MMTV-PyMT tumor induced faster tumor growths than GT198- cells when re-implanted into normal FVB/N mice. Together, this first study of GT198 vaccine in mouse showed its effectiveness in antitumor and anti-metastasis. The finding supports GT198 as a potential target in human immunotherapy since GT198 defect is shared in both human and mouse.
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Affiliation(s)
- Bhagelu R Achyut
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Hao Zhang
- Department of General Surgery, The First of Affiliated Hospital of Jinan University, And Institute of Precision Cancer Medicine and Pathology, Jinan University Medical College, Guangzhou, Guangdong, China; Research Center of Translational Medicine, The Second Affiliated Hospital of Shantou University Medical College, Shantou, China.
| | - Kartik Angara
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Nahid F Mivechi
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA; Department of Radiation Oncology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Ali S Arbab
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Lan Ko
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA; Department of Pathology, Medical College of Georgia, Augusta University, Augusta, GA, USA.
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7
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Gantchev J, Martínez Villarreal A, Gunn S, Zetka M, Ødum N, Litvinov IV. The ectopic expression of meiCT genes promotes meiomitosis and may facilitate carcinogenesis. Cell Cycle 2020; 19:837-854. [PMID: 32223693 DOI: 10.1080/15384101.2020.1743902] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Cancer meiomitosis is defined as the concurrent activation of both mitotic and meiotic machineries in neoplastic cells that confer a selective advantage together with increased genomic instability. MeiCT (meiosis-specific cancer/testis) genes that perform specialized functions in the germline events required for the first meiotic division are ectopically expressed in several cancers. Here we describe the expression profiles of meiCT genes and proteins across a number of cancers and review the proposed mechanisms that increase aneuploidy and elicit reduction division in polyploid cells. These mechanisms are centered on the overexpression and function of meiCT proteins in cancers under various conditions that includes a response to genotoxic stress. Since meiCT genes are transcriptionally repressed in somatic cells, their target offers a promising therapeutic approach with limited toxicity to healthy tissues. Throughout the review, we provide a detailed description of the roles for each gene in the context of meiosis and we discuss proposed functions and outcomes resulting from their ectopic reactivation in cancer.
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Affiliation(s)
- Jennifer Gantchev
- Division of Dermatology, Department of Medicine, McGill University Health Centre, Montreal, QC, Canada
| | | | - Scott Gunn
- Division of Dermatology, Department of Medicine, McGill University Health Centre, Montreal, QC, Canada
| | - Monique Zetka
- Department of Biology, McGill University, Montreal, QC, Canada
| | - Neils Ødum
- Department of Microbiology and Immunology, The University of Copenhagen, Copenhagen, Denmark
| | - Ivan V Litvinov
- Division of Dermatology, Department of Medicine, McGill University Health Centre, Montreal, QC, Canada
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8
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Crickard JB, Kwon Y, Sung P, Greene EC. Dynamic interactions of the homologous pairing 2 (Hop2)-meiotic nuclear divisions 1 (Mnd1) protein complex with meiotic presynaptic filaments in budding yeast. J Biol Chem 2019; 294:490-501. [PMID: 30420424 PMCID: PMC6333877 DOI: 10.1074/jbc.ra118.006146] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2018] [Revised: 11/02/2018] [Indexed: 12/19/2022] Open
Abstract
Homologous recombination (HR) is a universally conserved DNA repair pathway that can result in the exchange of genetic material. In eukaryotes, HR has evolved into an essential step in meiosis. During meiosis many eukaryotes utilize a two-recombinase pathway. This system consists of Rad51 and the meiosis-specific recombinase Dmc1. Both recombinases have distinct activities during meiotic HR, despite being highly similar in sequence and having closely related biochemical activities, raising the question of how these two proteins can perform separate functions. A likely explanation for their differential regulation involves the meiosis-specific recombination proteins Hop2 and Mnd1, which are part of a highly conserved eukaryotic protein complex that participates in HR, albeit through poorly understood mechanisms. To better understand how Hop2-Mnd1 functions during HR, here we used DNA curtains in conjunction with single-molecule imaging to measure and quantify the binding of the Hop2-Mnd1 complex from Saccharomyces cerevisiae to recombination intermediates comprising Rad51- and Dmc1-ssDNA in real time. We found that yeast Hop2-Mnd1 bound rapidly to Dmc1-ssDNA filaments with high affinity and remained bound for ∼1.3 min before dissociating. We also observed that this binding interaction was highly specific for Dmc1 and found no evidence for an association of Hop2-Mnd1 with Rad51-ssDNA or RPA-ssDNA. Our findings provide new quantitative insights into the binding dynamics of Hop2-Mnd1 with the meiotic presynaptic complex. On the basis of these findings, we propose a model in which recombinase specificities for meiotic accessory proteins enhance separation of the recombinases' functions during meiotic HR.
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Affiliation(s)
- J Brooks Crickard
- From the Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032
| | - Youngho Kwon
- the Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, and
- the Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Patrick Sung
- the Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, Connecticut 06520, and
- the Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, Texas 78229
| | - Eric C Greene
- From the Department of Biochemistry and Molecular Biophysics, Columbia University, New York, New York 10032,
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9
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Zhang L, Wang Y, Rashid MH, Liu M, Angara K, Mivechi NF, Maihle NJ, Arbab AS, Ko L. Malignant pericytes expressing GT198 give rise to tumor cells through angiogenesis. Oncotarget 2017; 8:51591-51607. [PMID: 28881671 PMCID: PMC5584272 DOI: 10.18632/oncotarget.18196] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 05/01/2017] [Indexed: 12/21/2022] Open
Abstract
Angiogenesis promotes tumor development. Understanding the crucial factors regulating tumor angiogenesis may reveal new therapeutic targets. Human GT198 (PSMC3IP or Hop2) is an oncoprotein encoded by a DNA repair gene that is overexpressed in tumor stromal vasculature to stimulate the expression of angiogenic factors. Here we show that pericytes expressing GT198 give rise to tumor cells through angiogenesis. GT198+ pericytes and perivascular cells are commonly present in the stromal compartment of various human solid tumors and rodent xenograft tumor models. In human oral cancer, GT198+ pericytes proliferate into GT198+ tumor cells, which migrate into lymph nodes. Increased GT198 expression is associated with increased lymph node metastasis and decreased progression-free survival in oral cancer patients. In rat brain U-251 glioblastoma xenografts, GT198+ pericytes of human tumor origin encase endothelial cells of rat origin to form mosaic angiogenic blood vessels, and differentiate into pericyte-derived tumor cells. The net effect is continued production of glioblastoma tumor cells from malignant pericytes via angiogenesis. In addition, activation of GT198 induces the expression of VEGF and promotes tube formation in cultured U251 cells. Furthermore, vaccination using GT198 protein as an antigen in mouse xenograft of GL261 glioma delayed tumor growth and prolonged mouse survival. Together, these findings suggest that GT198-expressing malignant pericytes can give rise to tumor cells through angiogenesis, and serve as a potential source of cells for distant metastasis. Hence, the oncoprotein GT198 has the potential to be a new target in anti-angiogenic therapies in human cancer.
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Affiliation(s)
- Liyong Zhang
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Yan Wang
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Mohammad H. Rashid
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Min Liu
- Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX, USA
| | - Kartik Angara
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Nahid F. Mivechi
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Nita J. Maihle
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA
- Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Ali S. Arbab
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Lan Ko
- Georgia Cancer Center, Medical College of Georgia, Augusta University, Augusta, GA, USA
- Department of Pathology, Medical College of Georgia, Augusta University, Augusta, GA, USA
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Schubert S, Ripperger T, Rood M, Petkidis A, Hofmann W, Frye-Boukhriss H, Tauscher M, Auber B, Hille-Betz U, Illig T, Schlegelberger B, Steinemann D. GT198 (PSMC3IP) germline variants in early-onset breast cancer patients from hereditary breast and ovarian cancer families. Genes Cancer 2017; 8:472-483. [PMID: 28435519 PMCID: PMC5369655 DOI: 10.18632/genesandcancer.132] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
GT198, located 470 kb downstream of BRCA1, encodes for the nuclear PSMC3-interacting protein, which functions as co-activator of steroid hormone-mediated gene expression, and is involved in RAD51 and DMC1-mediated homologous recombination during DNA repair of double-strand breaks. Recently, germline variants in GT198 have been identified in hereditary breast and ovarian cancer (HBOC) patients, mainly in cases with early-onset. We screened a cohort of 166 BRCA1/2 mutation-negative HBOC patients, of which 56 developed early-onset breast cancer before the age of 36 years, for GT198 variants. We identified 7 novel or rare GT198 variants in 8 out of 166 index patients: c.-115G>A (rs191843707); c.-70T>A (rs752276800); c.-37A>T (rs199620968); c.-24C>G (rs200359709); c.519G>A p.(Trp173*); c.537+51G>C (rs375509656); c.*24G>A. Three out of 7 identified variants (c.-115G>A, c.519G>A and c.*24G>A) with putative pathogenic impact were found in HBOC patients with breast cancer onset at ≤ 36 years. The nonsense mutation c.519G>A p.(Trp173*) was located within the DNA binding domain of GT198 and is predicted to induce nonsense-mediated mRNA decay. Functional analyses of c.-115G>A, and c.*24A>G indicated an influence of these variants on gene expression. This is the second study that gives evidence for an association between pathogenic GT198 germline variants and early-onset breast cancer in HBOC.
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Affiliation(s)
- Stephanie Schubert
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Tim Ripperger
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Melanie Rood
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Anthony Petkidis
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Winfried Hofmann
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | | | - Marcel Tauscher
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Bernd Auber
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
| | - Ursula Hille-Betz
- Department of Obstetrics and Gynecology, Hannover Medical School, Hannover, Germany
| | - Thomas Illig
- Department of Human Genetics, Hannover Medical School, Hannover, Germany.,Hannover Unified Biobank, Hannover Medical School, Hannover, Germany
| | | | - Doris Steinemann
- Department of Human Genetics, Hannover Medical School, Hannover, Germany
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11
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GT198 Expression Defines Mutant Tumor Stroma in Human Breast Cancer. THE AMERICAN JOURNAL OF PATHOLOGY 2016; 186:1340-50. [PMID: 27001628 DOI: 10.1016/j.ajpath.2016.01.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Revised: 12/02/2015] [Accepted: 01/14/2016] [Indexed: 12/19/2022]
Abstract
Human breast cancer precursor cells remain to be elucidated. Using breast cancer gene product GT198 (PSMC3IP; alias TBPIP or Hop2) as a unique marker, we revealed the cellular identities of GT198 mutant cells in human breast tumor stroma. GT198 is a steroid hormone receptor coactivator and a crucial factor in DNA repair. Germline mutations in GT198 are present in breast and ovarian cancer families. Somatic mutations in GT198 are present in ovarian tumor stromal cells. Herein, we show that human breast tumor stromal cells carry GT198 somatic mutations and express cytoplasmic GT198 protein. GT198(+) stromal cells share vascular smooth muscle cell origin, including myoepithelial cells, adipocytes, capillary pericytes, and stromal fibroblasts. Frequent GT198 mutations are associated with GT198(+) tumor stroma but not with GT198(-) tumor cells. GT198(+) progenitor cells are mostly capillary pericytes. When tested in cultured cells, mutant GT198 induces vascular endothelial growth factor promoter, and potentially promotes angiogenesis and adipogenesis. Our results suggest that multiple lineages of breast tumor stromal cells are mutated in GT198. These findings imply the presence of mutant progenitors, whereas their descendants, carrying the same GT198 mutations, are collectively responsible for forming breast tumor microenvironment. GT198 expression is, therefore, a specific marker of mutant breast tumor stroma and has the potential to facilitate diagnosis and targeted treatment of human breast cancer.
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12
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Rampler E, Stranzl T, Orban-Nemeth Z, Hollenstein DM, Hudecz O, Schlögelhofer P, Mechtler K. Comprehensive Cross-Linking Mass Spectrometry Reveals Parallel Orientation and Flexible Conformations of Plant HOP2-MND1. J Proteome Res 2015; 14:5048-62. [PMID: 26535604 DOI: 10.1021/acs.jproteome.5b00903] [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] [Indexed: 11/29/2022]
Abstract
The HOP2-MND1 heterodimer is essential for meiotic homologous recombination in plants and other eukaryotes and promotes the repair of DNA double-strand breaks. We investigated the conformational flexibility of HOP2-MND1, important for understanding the mechanistic details of the heterodimer, with chemical cross-linking in combination with mass spectrometry (XL-MS). The final XL-MS workflow encompassed the use of complementary cross-linkers, quenching, digestion, size exclusion enrichment, and HCD-based LC-MS/MS detection prior to data evaluation. We applied two different homobifunctional amine-reactive cross-linkers (DSS and BS(2)G) and one zero-length heterobifunctional cross-linker (EDC). Cross-linked peptides of four biological replicates were analyzed prior to 3D structure prediction by protein threading and protein-protein docking for cross-link-guided molecular modeling. Miniaturization of the size-exclusion enrichment step reduced the required starting material, led to a high amount of cross-linked peptides, and allowed the analysis of replicates. The major interaction site of HOP2-MND1 was identified in the central coiled-coil domains, and an open colinear parallel arrangement of HOP2 and MND1 within the complex was predicted. Moreover, flexibility of the C-terminal capping helices of both complex partners was observed, suggesting the coexistence of a closed complex conformation in solution.
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Affiliation(s)
- Evelyn Rampler
- Institute of Molecular Pathology , Dr.-Bohr-Gasse 7, 1030 Vienna, Austria.,Department of Analytical Chemistry, Faculty of Chemistry, University of Vienna , Währingerstr. 42, 1090 Vienna, Austria
| | - Thomas Stranzl
- Institute of Molecular Pathology , Dr.-Bohr-Gasse 7, 1030 Vienna, Austria
| | | | | | - Otto Hudecz
- Institute of Molecular Biotechnology, Austrian Academy of Sciences , Dr.-Bohr-Gasse 3, 1030 Vienna, Austria
| | | | - Karl Mechtler
- Institute of Molecular Pathology , Dr.-Bohr-Gasse 7, 1030 Vienna, Austria.,Institute of Molecular Biotechnology, Austrian Academy of Sciences , Dr.-Bohr-Gasse 3, 1030 Vienna, Austria
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Sansam CL, Pezza RJ. Connecting by breaking and repairing: mechanisms of DNA strand exchange in meiotic recombination. FEBS J 2015; 282:2444-57. [PMID: 25953379 PMCID: PMC4573575 DOI: 10.1111/febs.13317] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 03/26/2015] [Accepted: 05/06/2015] [Indexed: 01/03/2023]
Abstract
During prophase of meiosis I, homologous chromosomes interact and undergo recombination. Successful completion of these processes is required in order for the homologous chromosomes to mount the meiotic spindle as a pair. The organization of the chromosomes into pairs ensures orderly segregation to opposite poles of the dividing cell, such that each gamete receives one copy of each chromosome. Chiasmata, the cytological manifestation of crossover products of recombination, physically connect the homologs in pairs, providing a linkage that facilitates their segregation. Consequently, mutations that reduce the level of recombination are invariably associated with increased errors in meiotic chromosome segregation. In this review, we focus on recent biochemical and genetic advances in elucidating the mechanisms of meiotic DNA strand exchange catalyzed by the Dmc1 protein. We also discuss the mode by which two recombination mediators, Hop2 and Mnd1, facilitate rate-limiting steps of DNA strand exchange catalyzed by Dmc1.
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Affiliation(s)
- Christopher L Sansam
- Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation and the Department of Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
| | - Roberto J Pezza
- Cell Cycle and Cancer Biology Program, Oklahoma Medical Research Foundation and the Department of Cell Biology, University of Oklahoma Health Science Center, Oklahoma City, OK, USA
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Zhao W, Sung P. Significance of ligand interactions involving Hop2-Mnd1 and the RAD51 and DMC1 recombinases in homologous DNA repair and XX ovarian dysgenesis. Nucleic Acids Res 2015; 43:4055-66. [PMID: 25820426 PMCID: PMC4417169 DOI: 10.1093/nar/gkv259] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 03/16/2015] [Indexed: 01/01/2023] Open
Abstract
The evolutionarily conserved Hop2-Mnd1 complex is a key cofactor for the meiosis-specific recombinase Dmc1. However, emerging evidence has revealed that Hop2-Mnd1 is expressed in somatic tissues, primary human fibroblasts and cell lines, and that it functions in conjunction with the Rad51 recombinase to repair damaged telomeres via the alternate lengthening of telomeres mechanism. Here, we reveal how distinct DNA-binding activities of Hop2-Mnd1 mediate the stabilization of the RAD51-ssDNA presynaptic filament or stimulate the homologous DNA pairing reaction. We have also endeavored to define the interface that governs the assembly of the higher order complex of Hop2-Mnd1 with RAD51. Unexpectedly, we find that ATP enhances the interaction between Hop2-Mnd1 and RAD51, and that both Hop2 and Mnd1 are involved in RAD51 interaction via their C-terminal regions. Importantly, mutations introduced into these Hop2 and Mnd1 domains, including the HOP2 p.del201Glu mutation present in a patient of XX ovarian dysgenesis, diminish the association and functional synergy of Hop2-Mnd1 with both RAD51 and DMC1. Our findings help delineate the intricate manner in which Hop2-Mnd1 engages and functions with RAD51 and DMC1 in mammalian cells and speak to the possible cause of XX ovarian dysgenesis.
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Affiliation(s)
- Weixing Zhao
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
| | - Patrick Sung
- Department of Molecular Biophysics and Biochemistry, Yale University School of Medicine, New Haven, CT 06520, USA
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Peng M, Zhang H, Jaafar L, Risinger JI, Huang S, Mivechi NF, Ko L. Human ovarian cancer stroma contains luteinized theca cells harboring tumor suppressor gene GT198 mutations. J Biol Chem 2013; 288:33387-97. [PMID: 24097974 DOI: 10.1074/jbc.m113.485581] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Ovarian cancer is a highly lethal gynecological cancer, and its causes remain to be understood. Using a recently identified tumor suppressor gene, GT198 (PSMC3IP), as a unique marker, we searched for the identity of GT198 mutant cells in ovarian cancer. GT198 has germ line mutations in familial and early onset breast and ovarian cancers and recurrent somatic mutations in sporadic fallopian tube cancers. GT198 protein has been shown as a steroid hormone receptor coregulator and also as a crucial factor in DNA repair. In this study, using GT198 as a marker for microdissection, we find that ovarian tumor stromal cells harboring GT198 mutations are present in various types of ovarian cancer including high and low grade serous, endometrioid, mucinous, clear cell, and granulosa cell carcinomas and in precursor lesions such as inclusion cysts. The mutant stromal cells consist of a luteinized theca cell lineage at various differentiation stages including CD133(+), CD44(+), and CD34(+) cells, although the vast majority of them are differentiated overexpressing steroidogenic enzyme CYP17, a theca cell-specific marker. In addition, wild type GT198 suppresses whereas mutant GT198 protein stimulates CYP17 expression. The chromatin-bound GT198 on the human CYP17 promoter is decreased by overexpressing mutant GT198 protein, implicating the loss of wild type suppression in mutant cells. Together, our results suggest that GT198 mutant luteinized theca cells overexpressing CYP17 are common in ovarian cancer stroma. Because first hit cancer gene mutations would specifically mark cancer-inducing cells, the identification of mutant luteinized theca cells may add crucial evidence in understanding the cause of human ovarian cancer.
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