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Bruno S, Ghelli Luserna di Rorà A, Napolitano R, Soverini S, Martinelli G, Simonetti G. CDC20 in and out of mitosis: a prognostic factor and therapeutic target in hematological malignancies. J Exp Clin Cancer Res 2022; 41:159. [PMID: 35490245 PMCID: PMC9055704 DOI: 10.1186/s13046-022-02363-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2022] [Accepted: 04/11/2022] [Indexed: 12/31/2022] Open
Abstract
Cell division cycle 20 homologue (CDC20) is a well-known regulator of cell cycle, as it controls the correct segregation of chromosomes during mitosis. Many studies have focused on the biological role of CDC20 in cancer development, as alterations of its functionality have been linked to genomic instability and evidence demonstrated that high CDC20 expression levels are associated with poor overall survival in solid cancers. More recently, novel CDC20 functions have been demonstrated or suggested, including the regulation of apoptosis and stemness properties and a correlation with immune cell infiltration. Here, we here summarize and discuss the role of CDC20 inside and outside mitosis, starting from its network of interacting proteins. In the last years, CDC20 has also attracted more interest in the blood cancer field, being overexpressed and showing an association with prognosis both in myeloid and lymphoid malignancies. Preclinical findings showed that selective CDC20 and APC/CCDC20/APC/CCDH1 inhibitors, namely Apcin and proTAME, are effective against lymphoma and multiple myeloma cells, resulting in mitotic arrest and apoptosis and synergizing with clinically-relevant drugs. The evidence and hypothesis presented in this review provide the input for further biological and chemical studies aiming to dissect novel potential CDC20 roles and targeting strategies in hematological malignancies.
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Affiliation(s)
- Samantha Bruno
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna and Institute of Hematology "L. e A. Seràgnoli", Bologna, Italy
| | - Andrea Ghelli Luserna di Rorà
- Biosciences Laboratory, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", via Piero Maroncelli 40, 47014, Meldola, FC, Italy.
| | - Roberta Napolitano
- Biosciences Laboratory, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", via Piero Maroncelli 40, 47014, Meldola, FC, Italy
| | - Simona Soverini
- Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna and Institute of Hematology "L. e A. Seràgnoli", Bologna, Italy
| | - Giovanni Martinelli
- Scientific Directorate, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", via Piero Maroncelli 40, 47014, Meldola, FC, Italy
| | - Giorgia Simonetti
- Biosciences Laboratory, IRCCS Istituto Romagnolo per lo Studio dei Tumori (IRST) "Dino Amadori", via Piero Maroncelli 40, 47014, Meldola, FC, Italy
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Loontiens S, Vanhauwaert S, Depestel L, Dewyn G, Van Loocke W, Moore FE, Garcia EG, Batchelor L, Borga C, Squiban B, Malone-Perez M, Volders PJ, Olexiouk V, Van Vlierberghe P, Langenau DM, Frazer JK, Durinck K, Speleman F. A novel TLX1-driven T-ALL zebrafish model: comparative genomic analysis with other leukemia models. Leukemia 2020; 34:3398-3403. [PMID: 32591643 PMCID: PMC7906429 DOI: 10.1038/s41375-020-0938-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Revised: 06/14/2020] [Accepted: 06/16/2020] [Indexed: 12/17/2022]
Affiliation(s)
- Siebe Loontiens
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Suzanne Vanhauwaert
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Lisa Depestel
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Givani Dewyn
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Wouter Van Loocke
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Finola E Moore
- Department of Pathology, Massachusetts General Hospital Research Institute, Boston, MA, 02114, USA
- Center of Cancer Research, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Stem Cell Institute, Boston, MA, 02114, USA
- Center of Regenerative Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Elaine G Garcia
- Department of Pathology, Massachusetts General Hospital Research Institute, Boston, MA, 02114, USA
- Center of Cancer Research, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Stem Cell Institute, Boston, MA, 02114, USA
- Center of Regenerative Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - Lance Batchelor
- Section of Pediatric Hematology-Oncology, Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Chiara Borga
- Section of Pediatric Hematology-Oncology, Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Barbara Squiban
- Section of Pediatric Hematology-Oncology, Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Megan Malone-Perez
- Section of Pediatric Hematology-Oncology, Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Pieter-Jan Volders
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Volodimir Olexiouk
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - Pieter Van Vlierberghe
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
| | - David M Langenau
- Department of Pathology, Massachusetts General Hospital Research Institute, Boston, MA, 02114, USA
- Center of Cancer Research, Massachusetts General Hospital, Charlestown, MA, 02129, USA
- Harvard Stem Cell Institute, Boston, MA, 02114, USA
- Center of Regenerative Medicine, Massachusetts General Hospital, Boston, MA, 02114, USA
| | - J Kimble Frazer
- Section of Pediatric Hematology-Oncology, Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Kaat Durinck
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium.
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium.
| | - Frank Speleman
- Department of Biomolecular Medicine, Ghent University, Ghent, Belgium
- Cancer Research Institute Ghent (CRIG), Ghent, Belgium
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Shin SY, Lee ST, Kim HJ, Jang JH, Jung CW, Kim SH. A case of CD5-positive mature B-cell neoplasm with t(10;14)(q24;q11.2) and trisomy 12. Leuk Lymphoma 2014; 56:1550-1. [PMID: 25284493 DOI: 10.3109/10428194.2014.971408] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Krutikov K, Zheng Y, Chesney A, Huang X, Vaags AK, Evdokimova V, Hough MR, Chen E. Ectopic TLX1 expression accelerates malignancies in mice deficient in DNA-PK. PLoS One 2014; 9:e89649. [PMID: 24586935 PMCID: PMC3935916 DOI: 10.1371/journal.pone.0089649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 01/26/2014] [Indexed: 11/22/2022] Open
Abstract
The noncluster homeobox gene HOX11/TLX1 (TLX1) is detected at the breakpoint of the t(10;14)(q24;q11) chromosome translocation in patients with T cell acute lymphoblastic leukemia (T-ALL). This translocation results in the inappropriate expression of TLX1 in T cells. The oncogenic potential of TLX1 was demonstrated in IgHμ-TLX1Tg mice which develop mature B cell lymphoma after a long latency period, suggesting the requirement of additional mutations to initiate malignancy. To determine whether dysregulation of genes involved in the DNA damage response contributed to tumor progression, we crossed IgHμ-TLX1Tg mice with mice deficient in the DNA repair enzyme DNA-PK (PrkdcScid/Scid mice). IgHµ-TLX1TgPrkdcScid/Scid mice developed T-ALL and acute myeloid leukemia (AML) with reduced latency relative to control PrkdcScid/Scid mice. Further analysis of thymi from premalignant mice revealed greater thymic cellularity concomitant with increased thymocyte proliferation and decreased apoptotic index. Moreover, premalignant and malignant thymocytes exhibited impaired spindle checkpoint function, in association with aneuploid karyotypes. Gene expression profiling of premalignant IgHµ-TLX1TgPrkdcScid/Scid thymocytes revealed dysregulated expression of cell cycle, apoptotic and mitotic spindle checkpoint genes in double negative 2 (DN2) and DN3 stage thymocytes. Collectively, these findings reveal a novel synergy between TLX1 and impaired DNA repair pathway in leukemogenesis.
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Affiliation(s)
- Konstantin Krutikov
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Yanzhen Zheng
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Alden Chesney
- Department of Clinical Pathology, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
| | - Xiaoyong Huang
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Andrea K. Vaags
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Valentina Evdokimova
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
| | - Margaret R. Hough
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada
- * E-mail: (EC); (MRH)
| | - Edwin Chen
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
- Department of Molecular and Cellular Biology, Sunnybrook Research Institute, Toronto, Ontario, Canada
- * E-mail: (EC); (MRH)
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Zweier-Renn LA, Riz I, Hawley TS, Hawley RG. The DN2 Myeloid-T (DN2mt) Progenitor is a Target Cell for Leukemic Transformation by the TLX1 Oncogene. JOURNAL OF BONE MARROW RESEARCH 2013; 1:105. [PMID: 25309961 PMCID: PMC4191823 DOI: 10.4172/2329-8820.1000105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
INTRODUCTION Inappropriate activation of the TLX1 (T-cell leukemia homeobox 1) gene by chromosomal translocation is a recurrent event in human T-cell Acute Lymphoblastic Leukemia (T-ALL). Ectopic expression of TLX1 in murine bone marrow progenitor cells using a conventional retroviral vector efficiently yields immortalized cell lines and induces T-ALL-like tumors in mice after long latency. METHODS To eliminate a potential contribution of retroviral insertional mutagenesis to TLX1 immortalizing and transforming function, we incorporated the TLX1 gene into an insulated self-inactivating retroviral vector. RESULTS Retrovirally transduced TLX1-expressing murine bone marrow progenitor cells had a growth/survival advantage and readily gave rise to immortalized cell lines. Extensive characterization of 15 newly established cell lines failed to reveal a common retroviral integration site. This comprehensive analysis greatly extends our previous study involving a limited number of cell lines, providing additional support for the view that constitutive TLX1 expression is sufficient to initiate the series of events culminating in hematopoietic progenitor cell immortalization. When TLX1-immortalized cells were co-cultured on OP9-DL1 monolayers under conditions permissive for T-cell differentiation, a latent T-lineage potential was revealed. However, the cells were unable to transit the DN2 myeloid-T (DN2mt)-DN2 T-lineage determined (DN2t) commitment step. The differentiation block coincided with failure to upregulate the zinc finger transcription factor gene Bcl11b, the human ortholog of which was shown to be a direct transcriptional target of TLX1 downregulated in the TLX1+ T-ALL cell line ALL-SIL. Other studies have described the ability of TLX1 to promote bypass of mitotic checkpoint arrest, leading to aneuploidy. We likewise found that diploid TLX1-expressing DN2mt cells treated with the mitotic inhibitor paclitaxel bypassed the mitotic checkpoint and displayed chromosomal instability. This was associated with elevated expression of TLX1 transcriptional targets involved in DNA replication and mitosis, including Ccna2 (cyclin A2), Ccnb1 (cyclin B1), Ccnb2 (cyclin B2) and Top2a (topoisomerase IIα). Notably, enforced expression of BCL11B in ALL-SIL T-ALL cells conferred resistance to the topoisomerase IIα poison etoposide. CONCLUSION Taken together with previous findings, the data reinforce a mechanism of TLX1 oncogenic activity linked to chromosomal instability resulting from dysregulated expression of target genes involved in mitotic processes. We speculate that repression of BCL11B expression may provide part of the explanation for the observation that aneuploid DNA content in TLX1+ leukemic T cells does not necessarily portend an unfavorable prognosis. This TLX1 hematopoietic progenitor cell immortalization/T-cell differentiation assay should help further our understanding of the mechanisms of TLX1-mediated evolution to malignancy and has the potential to be a useful predictor of disease response to novel therapeutic agents in TLX1+ T-ALL.
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Affiliation(s)
- Lynnsey A Zweier-Renn
- Department of Anatomy and Regenerative Biology, George Washington University, Washington, DC, USA
- Graduate Program in Biochemistry and Molecular Genetics, George Washington University, Washington, DC, USA
| | - Irene Riz
- Department of Anatomy and Regenerative Biology, George Washington University, Washington, DC, USA
| | - Teresa S Hawley
- Flow Cytometry Core Facility, George Washington University, Washington, DC, USA
| | - Robert G Hawley
- Department of Anatomy and Regenerative Biology, George Washington University, Washington, DC, USA
- Sino-US Joint Laboratory of Translational Medicine, Jining Medical University Affiliated Hospital, Jining Medical University, Jining, Shandong, China
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De Keersmaecker K, Ferrando AA. TLX1-Induced T-cell Acute Lymphoblastic Leukemia: Figure 1. Clin Cancer Res 2011; 17:6381-6. [DOI: 10.1158/1078-0432.ccr-10-3037] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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McLean JR, Chaix D, Ohi MD, Gould KL. State of the APC/C: organization, function, and structure. Crit Rev Biochem Mol Biol 2011; 46:118-36. [PMID: 21261459 DOI: 10.3109/10409238.2010.541420] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The ubiquitin-proteasome protein degradation system is involved in many essential cellular processes including cell cycle regulation, cell differentiation, and the unfolded protein response. The anaphase-promoting complex/cyclosome (APC/C), an evolutionarily conserved E3 ubiquitin ligase, was discovered 15 years ago because of its pivotal role in cyclin degradation and mitotic progression. Since then, we have learned that the APC/C is a very large, complex E3 ligase composed of 13 subunits, yielding a molecular machine of approximately 1 MDa. The intricate regulation of the APC/C is mediated by the Cdc20 family of activators, pseudosubstrate inhibitors, protein kinases and phosphatases and the spindle assembly checkpoint. The large size, complexity, and dynamic nature of the APC/C represent significant obstacles toward high-resolution structural techniques; however, over the last decade, there have been a number of lower resolution APC/C structures determined using single particle electron microscopy. These structures, when combined with data generated from numerous genetic and biochemical studies, have begun to shed light on how APC/C activity is regulated. Here, we discuss the most recent developments in the APC/C field concerning structure, substrate recognition, and catalysis.
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Affiliation(s)
- Janel R McLean
- Howard Hughes Medical Institute, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
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9
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De Keersmaecker K, Real PJ, Gatta GD, Palomero T, Sulis ML, Tosello V, Van Vlierberghe P, Barnes K, Castillo M, Sole X, Hadler M, Lenz J, Aplan PD, Kelliher M, Kee BL, Pandolfi PP, Kappes D, Gounari F, Petrie H, Van der Meulen J, Speleman F, Paietta E, Racevskis J, Wiernik PH, Rowe JM, Soulier J, Avran D, Cavé H, Dastugue N, Raimondi S, Meijerink JPP, Cordon-Cardo C, Califano A, Ferrando AA. The TLX1 oncogene drives aneuploidy in T cell transformation. Nat Med 2010; 16:1321-7. [PMID: 20972433 PMCID: PMC2974790 DOI: 10.1038/nm.2246] [Citation(s) in RCA: 121] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Accepted: 09/21/2010] [Indexed: 11/09/2022]
Abstract
The TLX1 transcription factor oncogene plays an important role in the pathogenesis of T-cell acute lymphoblastic leukemia (T-ALL). However, the specific mechanisms of T-cell transformation downstream of TLX1 remain to be elucidated. Here we show that forced expression of TLX1 in transgenic mice induces T-ALL tumors with frequent deletions and mutations in Bcl11b, and identify the presence of recurrent mutations and deletions in BCL11B in 16% of human T-ALLs. Most notably, mouse TLX1 tumors were typically aneuploid and showed a marked defect in the activation of the mitotic checkpoint. Mechanistically, TLX1 directly downregulates the expression of CHEK1 and additional mitotic control genes and induces loss of the mitotic checkpoint in non transformed preleukemic thymocytes. These results identify a novel mechanism contributing to chromosomal missegregation and aneuploidy active at the earliest stages of tumor development in the pathogenesis of cancer.
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Chen E, Huang X, Zheng Y, Li YJ, Chesney A, Ben-David Y, Yang E, Hough MR. Phosphorylation of HOX11/TLX1 on Threonine-247 during mitosis modulates expression of cyclin B1. Mol Cancer 2010; 9:246. [PMID: 20846384 PMCID: PMC2949800 DOI: 10.1186/1476-4598-9-246] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2010] [Accepted: 09/16/2010] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND The HOX11/TLX1 (hereafter referred to as HOX11) homeobox gene was originally identified at a t(10;14)(q24;q11) translocation breakpoint, a chromosomal abnormality observed in 5-7% of T cell acute lymphoblastic leukemias (T-ALLs). We previously reported a predisposition to aberrant spindle assembly checkpoint arrest and heightened incidences of chromosome missegregation in HOX11-overexpressing B lymphocytes following exposure to spindle poisons. The purpose of the current study was to evaluate cell cycle specific expression of HOX11. RESULTS Cell cycle specific expression studies revealed a phosphorylated form of HOX11 detectable only in the mitotic fraction of cells after treatment with inhibitors to arrest cells at different stages of the cell cycle. Mutational analyses revealed phosphorylation on threonine-247 (Thr247), a conserved amino acid that defines the HOX11 gene family and is integral for the association with DNA binding elements. The effect of HOX11 phosphorylation on its ability to modulate expression of the downstream target, cyclin B1, was tested. A HOX11 mutant in which Thr247 was substituted with glutamic acid (HOX11 T247E), thereby mimicking a constitutively phosphorylated HOX11 isoform, was unable to bind the cyclin B1 promoter or enhance levels of the cyclin B1 protein. Expression of the wildtype HOX11 was associated with accelerated progression through the G2/M phase of the cell cycle, impaired synchronization in prometaphase and reduced apoptosis whereas expression of the HOX11 T247E mutant restored cell cycle kinetics, the spindle checkpoint and apoptosis. CONCLUSIONS Our results demonstrate that the transcriptional activity of HOX11 is regulated by phosphorylation of Thr247 in a cell cycle-specific manner and that this phosphorylation modulates the expression of the target gene, cyclin B1. Since it is likely that Thr247 phosphorylation regulates DNA binding activity to multiple HOX11 target sequences, it is conceivable that phosphorylation functions to regulate the expression of HOX11 target genes involved in the control of the mitotic spindle checkpoint.
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Affiliation(s)
- Edwin Chen
- Institute of Medical Science, University of Toronto, Toronto, Ontario M5S1A8, Canada
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Huang X, Andreu-Vieyra CV, York JP, Hatcher R, Lu T, Matzuk MM, Zhang P. Inhibitory phosphorylation of separase is essential for genome stability and viability of murine embryonic germ cells. PLoS Biol 2008; 6:e15. [PMID: 18232736 PMCID: PMC2214812 DOI: 10.1371/journal.pbio.0060015] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Indexed: 11/23/2022] Open
Abstract
Activity of separase, a cysteine protease that cleaves sister chromatid cohesin at the onset of anaphase, is tightly regulated to ensure faithful chromosome segregation and genome stability. Two mechanisms negatively regulate separase: inhibition by securin and phosphorylation on serine 1121. To gauge the physiological significance of the inhibitory phosphorylation, we created a mouse strain in which Ser1121 was mutated to Ala (S1121A). Here we report that this S1121A point mutation causes infertility in mice. We show that germ cells in the mutants are depleted during development. We further demonstrate that S1121A causes chromosome misalignment during proliferation of the postmigratory primordial germ cells, resulting in mitotic arrest, aneuploidy, and eventual cell death. Our results indicate that inhibitory phosphorylation of separase plays a critical role in the maintenance of sister chromatid cohesion and genome stability in proliferating postmigratory primordial germ cells. Higher eukaryotes rely on a separate cell lineage, the germline, to pass genetic information from generation to generation. To ensure faithful transmission of genetic information, cell cycle checkpoint mechanisms are engaged during mitotic and meiotic divisions of germ cells. The identity and function of these checkpoints is not well understood. In mammals, the germline is specified early in embryogenesis as primordial germ cells (PGCs) at the epiblast stage (around embryonic day 5.0 in mice). PGCs then migrate out from their birthplace and arrive at the genital ridge several days later. In the genital ridge, PGCs undergo a great expansion in number through mitosis. During this expansion, PGCs critically depend on the inhibitory phosphorylation of separase to prevent premature separation of sister chromatids and hence progeny with abnormal chromosome number. Separase is a protease which cleaves the Scc1 subunit of sister chromatid cohesin complex. Its activity must be suppressed before all sisters are aligned at the metaphase plate. Two mechanisms are known that can inhibit separase: phosphorylation and binding by securin, both of which are activated at the spindle assembly checkpoint. Although these two mechanisms are redundant in somatic cells, our results indicate that the inhibitory phosphorylation of separase is uniquely required in the germline. A single point mutation of separase that blocks its phosphorylation has a profound and dominant effect on germ cell biology.
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Affiliation(s)
- Xingxu Huang
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Claudia V Andreu-Vieyra
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
| | - J. Philippe York
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Rashieda Hatcher
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Tao Lu
- Department of Experimental Therapeutics, University of Texas MD Anderson Cancer Center, Houston, Texas, United States of America
| | - Martin M Matzuk
- Department of Pathology, Baylor College of Medicine, Houston, Texas, United States of America
| | - Pumin Zhang
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, Texas, United States of America
- Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, Texas, United States of America
- * To whom correspondence should be addressed. E-mail:
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Rice KL, Izon DJ, Ford J, Boodhoo A, Kees UR, Greene WK. Overexpression of stem cell associated ALDH1A1, a target of the leukemogenic transcription factor TLX1/HOX11, inhibits lymphopoiesis and promotes myelopoiesis in murine hematopoietic progenitors. Leuk Res 2007; 32:873-83. [PMID: 18082256 DOI: 10.1016/j.leukres.2007.11.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2007] [Revised: 11/01/2007] [Accepted: 11/02/2007] [Indexed: 02/01/2023]
Abstract
TLX1/HOX11 is an oncogenic transcription factor in human T-cell leukemia, however, the molecular basis for its transforming activity has remained elusive. The ALDH1A1 gene, whose product participates in retinoic acid synthesis, was previously identified as a TLX1-responsive gene. Here, we confirm regulation of ALDH1A1 transcription by TLX1 and show that ALDH1A1 can profoundly perturb murine hematopoiesis by promoting myeloid differentiation at the expense of lymphopoiesis. Together, these data demonstrate that ALDH1A1 plays a key role in normal hematopoiesis, and confirm ALDH1A1 as a TLX1 transcriptional target that may contribute to the ability of this homeoprotein to alter cell fate and induce tumor growth.
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Affiliation(s)
- Kim L Rice
- School of Veterinary and Biomedical Sciences, Division of Health Sciences, Murdoch University, South Street, Murdoch, Perth WA 6150, Australia
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13
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Chen E, Kwon YT, Lim MS, Dubé ID, Hough MR. Loss of Ubr1 promotes aneuploidy and accelerates B-cell lymphomagenesis in TLX1/HOX11-transgenic mice. Oncogene 2006; 25:5752-63. [PMID: 16862188 DOI: 10.1038/sj.onc.1209573] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The TLX1/HOX11 homeobox gene was originally identified at the recurrent t(10;14)(q24;q11) translocation breakpoint, a chromosomal abnormality observed in 5-7% of T-cell acute lymphoblastic leukemias (T-ALLs). Proviral insertional mutagenesis studies performed on transgenic mice ectopically expressing TLX1/HOX11 in B lymphocytes (IgHmu-HOX11(Tg) mice) revealed the Ubr1 gene locus as a frequent site of proviral insertion, concomitant with accelerated development of diffuse large B-cell lymphoma. Insertion into this genomic region was confirmed by Southern blotting and by the ability to generate a polymerase chain reaction (PCR) amplicon across the viral-genome junction. Western immunoblot and semiquantitative reverse transcriptase-PCR analysis revealed downregulated expression of the Ubr1 gene product subsequent to viral integration. Loss or reduced levels of Ubr1 expression was associated with 5/14 spontaneous B-cell lymphomas in IgHmu-HOX11(Tg) mice and one of nine primary human T-ALLs. To gain mechanistic insight into the cooperativity between TLX1/HOX11 and Ubr1, IgHmu-HOX11(Tg)/Ubr1(-/-) mice were generated. IgHmu-HOX11(Tg)/Ubr1(-/-) mice exhibited a modest but statistically significant acceleration of disease onset relative to IgHmu-HOX11(Tg)/Ubr1(+/-) mice. Moreover, micronucleus assays to detect for chromosome missegregation were conducted and revealed increased presence of micronuclei in IgHmu-HOX11(Tg)/Ubr1(-/-) primary B lymphocyte cultures, and in both TLX1/HOX11-overexpressing T cell lines and fibroblast cultures following transfection with short interfering RNAs (siRNAs) targeting Ubr1. Karyotyping of primary B lymphocyte cultures revealed increased incidences of hypodiploid karyotypes. Finally, mitotic figures analysed from Ubr1 siRNA-transfected fibroblast cultures revealed no defects in chromosome congression to the metaphase plate, but increased incidences of atypical anaphase figures, including the development of anaphase bridges and lagging chromosomes. Based on these findings, we identify a synergistic role between TLX1/HOX11 overexpression and Ubr1 inactivation in promoting chromosome missegregation, permitting the accrual of additional chromosome losses and cytogenic abnormalities en route to malignancy.
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Affiliation(s)
- E Chen
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada
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Bapat SA. Evolution of cancer stem cells. Semin Cancer Biol 2006; 17:204-13. [PMID: 16787749 DOI: 10.1016/j.semcancer.2006.05.001] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Revised: 05/08/2006] [Accepted: 05/09/2006] [Indexed: 12/31/2022]
Abstract
Cancer as a disease driven by cancer stem cells is a concept that has emerged over the last few years. However, several issues relating to this phenomenon as yet remain unaddressed. A fundamental question is one relating to the identification of events leading to transformation of a normal tissue stem cell to a cancer stem cell. Complete knowledge of this evolutionary process may be crucial for the development of novel effective therapies that influence patient prognosis. The scope of this review is to discuss reports that have begun to elucidate stem cell transformation either as an isolated event or as a progression as an attempt towards understanding some of the critical events involved in the process.
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Affiliation(s)
- S A Bapat
- National Centre for Cell Science, Ganeshkhind, Pune 411007, India.
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