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Perlee S, Kikuchi S, Nakadai T, Masuda T, Ohtsuki S, Matsumoto M, Rahmutulla B, Fukuyo M, Cifani P, Kentsis A, Roeder RG, Kaneda A, Hoshii T. SETD1A function in leukemia is mediated through interaction with mitotic regulators BuGZ/BUB3. EMBO Rep 2023; 24:e57108. [PMID: 37535603 PMCID: PMC10561176 DOI: 10.15252/embr.202357108] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 07/11/2023] [Accepted: 07/18/2023] [Indexed: 08/05/2023] Open
Abstract
The H3K4 methyltransferase SETD1A plays a crucial role in leukemia cell survival through its noncatalytic FLOS domain-mediated recruitment of cyclin K and regulation of DNA damage response genes. In this study, we identify a functional nuclear localization signal in and interaction partners of the FLOS domain. Our screen for FLOS domain-binding partners reveals that the SETD1A FLOS domain binds mitosis-associated proteins BuGZ/BUB3. Inhibition of both cyclin K and BuGZ/BUB3-binding motifs in SETD1A shows synergistic antileukemic effects. BuGZ/BUB3 localize to SETD1A-bound promoter-TSS regions and SETD1A-negative H3K4me1-positive enhancer regions adjacent to SETD1A target genes. The GLEBS motif and intrinsically disordered region of BuGZ are required for both SETD1A-binding and leukemia cell proliferation. Cell-cycle-specific SETD1A restoration assays indicate that SETD1A expression at the G1/S phase of the cell cycle promotes both the expression of DNA damage response genes and cell cycle progression in leukemia cells.
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Affiliation(s)
- Sarah Perlee
- Department of Cancer Biology and GeneticsMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
- Gerstner Graduate School of Biomedical SciencesMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Sota Kikuchi
- Department of Molecular Oncology, Graduate School of MedicineChiba UniversityChibaJapan
| | - Tomoyoshi Nakadai
- Laboratory of Biochemistry and Molecular BiologyThe Rockefeller UniversityNew YorkNYUSA
| | - Takeshi Masuda
- Laboratory of Pharmaceutical Microbiology, Faculty of Life SciencesKumamoto UniversityKumamotoJapan
- Institute for Advanced BiosciencesKeio UniversityTsuruokaJapan
| | - Sumio Ohtsuki
- Laboratory of Pharmaceutical Microbiology, Faculty of Life SciencesKumamoto UniversityKumamotoJapan
| | - Makoto Matsumoto
- Department of Molecular Oncology, Graduate School of MedicineChiba UniversityChibaJapan
| | - Bahityar Rahmutulla
- Department of Molecular Oncology, Graduate School of MedicineChiba UniversityChibaJapan
| | - Masaki Fukuyo
- Department of Molecular Oncology, Graduate School of MedicineChiba UniversityChibaJapan
| | - Paolo Cifani
- Molecular Pharmacology ProgramMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Alex Kentsis
- Molecular Pharmacology ProgramMemorial Sloan Kettering Cancer CenterNew YorkNYUSA
| | - Robert G Roeder
- Laboratory of Biochemistry and Molecular BiologyThe Rockefeller UniversityNew YorkNYUSA
| | - Atsushi Kaneda
- Department of Molecular Oncology, Graduate School of MedicineChiba UniversityChibaJapan
| | - Takayuki Hoshii
- Department of Molecular Oncology, Graduate School of MedicineChiba UniversityChibaJapan
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Kitagawa R, Niikura Y, Becker A, Houghton PJ, Kitagawa K. EWSR1 maintains centromere identity. Cell Rep 2023; 42:112568. [PMID: 37243594 PMCID: PMC10758295 DOI: 10.1016/j.celrep.2023.112568] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 04/03/2023] [Accepted: 05/11/2023] [Indexed: 05/29/2023] Open
Abstract
The centromere is essential for ensuring high-fidelity transmission of chromosomes. CENP-A, the centromeric histone H3 variant, is thought to be the epigenetic mark of centromere identity. CENP-A deposition at the centromere is crucial for proper centromere function and inheritance. Despite its importance, the precise mechanism responsible for maintenance of centromere position remains obscure. Here, we report a mechanism to maintain centromere identity. We demonstrate that CENP-A interacts with EWSR1 (Ewing sarcoma breakpoint region 1) and EWSR1-FLI1 (the oncogenic fusion protein in Ewing sarcoma). EWSR1 is required for maintaining CENP-A at the centromere in interphase cells. EWSR1 and EWSR1-FLI1 bind CENP-A through the SYGQ2 region within the prion-like domain, important for phase separation. EWSR1 binds to R-loops through its RNA-recognition motif in vitro. Both the domain and motif are required for maintaining CENP-A at the centromere. Therefore, we conclude that EWSR1 guards CENP-A in centromeric chromatins by binding to centromeric RNA.
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Affiliation(s)
- Risa Kitagawa
- Greehey Children's Cancer Research Institute, Mays Cancer Center, Department of Molecular Medicine, UT Health Science Center San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229-3000, USA
| | - Yohei Niikura
- Greehey Children's Cancer Research Institute, Mays Cancer Center, Department of Molecular Medicine, UT Health Science Center San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229-3000, USA
| | - Argentina Becker
- Greehey Children's Cancer Research Institute, Mays Cancer Center, Department of Molecular Medicine, UT Health Science Center San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229-3000, USA
| | - Peter J Houghton
- Greehey Children's Cancer Research Institute, Mays Cancer Center, Department of Molecular Medicine, UT Health Science Center San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229-3000, USA
| | - Katsumi Kitagawa
- Greehey Children's Cancer Research Institute, Mays Cancer Center, Department of Molecular Medicine, UT Health Science Center San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229-3000, USA.
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Ren F, Ning H, Ge Y, Yin Z, Chen L, Hu D, Shen S, Wang X, Wang S, Li R, He J. Bisphenol A Induces Apoptosis in Response to DNA Damage through c-Abl/YAPY357/ p73 Pathway in P19 Embryonal Carcinoma Stem Cells. Toxicology 2022; 470:153138. [DOI: 10.1016/j.tox.2022.153138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2021] [Revised: 02/16/2022] [Accepted: 02/22/2022] [Indexed: 12/22/2022]
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Niikura Y, Kitagawa R, Fang L, Kitagawa K. CENP-A Ubiquitylation Is Indispensable to Cell Viability. Dev Cell 2020; 50:683-689.e6. [PMID: 31550462 DOI: 10.1016/j.devcel.2019.07.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 04/30/2019] [Accepted: 07/14/2019] [Indexed: 01/10/2023]
Abstract
CENP-A is a centromere-specific histone H3 variant that epigenetically determines centromere identity, but how CENP-A is deposited at the centromere remains obscure. We previously reported that CENP-A K124 ubiquitylation, mediated by the CUL4A-RBX1-COPS8 complex, is essential for CENP-A deposition at the centromere. However, a recent report stated that CENP-A K124R mutants show no defects in centromere localization and cell viability. In the present study, we found that EYFP tagging induces additional ubiquitylation of EYFP-CENP-A K124R, which allows the mutant protein to bind to HJURP. Using a previously developed conditional CENP-A knockout system and our CENP-A K124R knockin mutant created by the CRISPR-Cas9 system, we show that the Flag-tagged or untagged CENP-A K124R mutant is lethal. This lethality is rescued by monoubiquitin fusion, indicating that CENP-A ubiquitylation is essential for viability.
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Affiliation(s)
- Yohei Niikura
- Greehey Children's Cancer Research Institute, Department of Molecular Medicine, UT Health Science Center San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229-3000, USA; MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing University, Nanjing, Jiangsu Province 210061, China.
| | - Risa Kitagawa
- Greehey Children's Cancer Research Institute, Department of Molecular Medicine, UT Health Science Center San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229-3000, USA
| | - Lei Fang
- Jiangsu Key Laboratory of Molecular Medicine, Medical School of Nanjing University, Nanjing, Jiangsu Province 210093, China
| | - Katsumi Kitagawa
- Greehey Children's Cancer Research Institute, Department of Molecular Medicine, UT Health Science Center San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229-3000, USA.
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Yadav MK, Manoli NM, Vimalraj S, Madhunapantula SV. Unmethylated promoter DNA correlates with p53 expression and apoptotic levels only in Vitamin B9 and B12 deficient megaloblastic anemia but not in non-megaloblastic anemia controls. Int J Biol Macromol 2017; 109:76-84. [PMID: 29246873 DOI: 10.1016/j.ijbiomac.2017.12.070] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 12/08/2017] [Accepted: 12/11/2017] [Indexed: 12/12/2022]
Abstract
Cyanocobalamin (Vitamin B12, VB12) and Folic acid (Vitamin B9, VB9) deficiency leads to anemia in women. We have recently shown low VB12 and VB9 levels in the serum of megaloblastic anemia (MBA) patients. Further, our study demonstrated elevated homocysteine and p53, respectively, in the serum and bone marrow aspirates of MBA patients but not in non-MBA subjects. However, it is unknown whether any gender specific variation in VB12 and VB9 level exists in MBA and non-MBA patients? In addition, it is unclear whether low VB12 and VB9 has a role in the regulation of p53 expression in MBA patients? And whether elevated p53 is functionally active? If so, does bone marrow aspirates of MBA patients show elevated apoptosis. Hence, we have analyzed VB12 and VB9 levels in MBA patients and compared with non-MBA subjects. Next, methylation status of p53 promoter was determined and correlated with p53 expression. Furthermore, the level of apoptosis in bone marrow aspirate paraffin blocks was estimated using TUNEL staining. In conclusion, low VB12 and VB9 in male and female patients directly correlate with p53 promoter unmethylation status, but, inversely correlate with p53 protein expression and its activity, only in MBA cases but not in non-MBA controls.
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Affiliation(s)
- Manish K Yadav
- Center of Excellence in Molecular Biology and Regenerative Medicine (CEMR), Department of Biochemistry, JSS Medical College, Jagadguru Sri Shivarathreeshwara University (Accredited "A" Grade by NAAC and Ranked 45 by National Institutional Ranking Framework (NIRF)-2016, Ministry of Human Resource Development, Government of India), Mysuru, 570015, Karnataka, India
| | - Nandini M Manoli
- Department of Pathology, JSS Medical College, Jagadguru Sri Shivarathreeshwara University (Accredited "A" Grade by NAAC and Ranked 45 by National Institutional Ranking Framework (NIRF)-2016, Ministry of Human Resource Development, Government of India), Mysuru, 570015, Karnataka, India
| | - Selvaraj Vimalraj
- Vascular Biology Lab, AU-KBC Research Centre, MIT campus, Anna University, Chennai, 600044, Tamil Nadu, India.
| | - SubbaRao V Madhunapantula
- Center of Excellence in Molecular Biology and Regenerative Medicine (CEMR), Department of Biochemistry, JSS Medical College, Jagadguru Sri Shivarathreeshwara University (Accredited "A" Grade by NAAC and Ranked 45 by National Institutional Ranking Framework (NIRF)-2016, Ministry of Human Resource Development, Government of India), Mysuru, 570015, Karnataka, India.
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Niikura Y, Kitagawa R, Ogi H, Kitagawa K. SGT1-HSP90 complex is required for CENP-A deposition at centromeres. Cell Cycle 2017; 16:1683-1694. [PMID: 28816574 PMCID: PMC5602426 DOI: 10.1080/15384101.2017.1325039] [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: 11/22/2022] Open
Abstract
The centromere plays an essential role in accurate chromosome segregation, and defects in its function lead to aneuploidy and thus cancer. The centromere-specific histone H3 variant CENP-A is proposed to be the epigenetic mark of the centromere, as active centromeres require CENP-A–containing nucleosomes to direct the recruitment of multiple kinetochore proteins. CENP-A K124 ubiquitylation, mediated by CUL4A-RBX1-COPS8 E3 ligase activity, is required for CENP-A deposition at the centromere. However, the mechanism that controls the E3 ligase activity of the CUL4A-RBX1-COPS8 complex remains obscure. We have discovered that the SGT1-HSP90 complex is required for recognition of CENP-A by COPS8. Thus, the SGT1-HSP90 complex contributes to the E3 ligase activity of the CUL4A complex that is necessary for CENP-A ubiquitylation and CENP-A deposition at the centromere.
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Affiliation(s)
- Yohei Niikura
- a Greehey Children's Cancer Research Institute , Department of Molecular Medicine, UT Health Science Center San Antonio School of Medicine , San Antonio , TX , USA.,b The Research Institute at Nationwide Children's Hospital , Columbus , OH , USA
| | - Risa Kitagawa
- a Greehey Children's Cancer Research Institute , Department of Molecular Medicine, UT Health Science Center San Antonio School of Medicine , San Antonio , TX , USA.,b The Research Institute at Nationwide Children's Hospital , Columbus , OH , USA
| | - Hiroo Ogi
- b The Research Institute at Nationwide Children's Hospital , Columbus , OH , USA
| | - Katsumi Kitagawa
- a Greehey Children's Cancer Research Institute , Department of Molecular Medicine, UT Health Science Center San Antonio School of Medicine , San Antonio , TX , USA.,b The Research Institute at Nationwide Children's Hospital , Columbus , OH , USA
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BUB1 and SURVIVIN proteins are not degraded after a prolonged mitosis and accumulate in the nuclei of HCT116 cells. Cell Death Discov 2016; 2:16079. [PMID: 27818790 PMCID: PMC5081682 DOI: 10.1038/cddiscovery.2016.79] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2016] [Revised: 08/24/2016] [Accepted: 09/15/2016] [Indexed: 12/20/2022] Open
Abstract
Spindle poisons activate the spindle assembly checkpoint and prevent mitotic exit until cells die or override the arrest. Several studies have focused on spindle poison-mediated cell death, but less is known about consequences in cells that survive a mitotic arrest. During mitosis, proteins such as CYCLIN B, SECURIN, BUB1 and SURVIVIN are degraded in order to allow mitotic exit, and these proteins are maintained at low levels in the next interphase. In contrast, exit from a prolonged mitosis depends only on degradation of CYCLIN B; it is not known whether the levels of other proteins decrease or remain high. Here, we analyzed the levels and localization of the BUB1 and SURVIVIN proteins in cells that escaped from a paclitaxel-mediated prolonged mitosis. We compared cells with a short arrest (HCT116 cells) with cells that spent more time in mitosis (HT29 cells) after paclitaxel treatment. BUB1 and SURVIVIN were not degraded and remained localized to the nuclei of HCT116 cells after a mitotic arrest. Moreover, BUB1 nuclear foci were observed; BUB1 did not colocalize with centromere proteins. In HT29 cells, the levels of BUB1 and SURVIVIN decreased during the arrest, and these proteins were not present in cells that reached the next interphase. Using time-lapse imaging, we observed morphological heterogeneity in HCT116 cells that escaped from the arrest; this heterogeneity was due to the cytokinesis-like mechanism by which the cells exited mitosis. Thus, our results show that high levels of BUB1 and SURVIVIN can be maintained after a mitotic arrest, which may promote resistance to cell death.
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8
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Niikura Y, Kitagawa K. Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins. J Vis Exp 2016:e53732. [PMID: 26967065 PMCID: PMC4828215 DOI: 10.3791/53732] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
"Centromeres" and "kinetochores" refer to the site where chromosomes associate with the spindle during cell division. Direct visualization of centromere-kinetochore proteins during the cell cycle remains a fundamental tool in investigating the mechanism(s) of these proteins. Advanced imaging methods in fluorescence microscopy provide remarkable resolution of centromere-kinetochore components and allow direct observation of specific molecular components of the centromeres and kinetochores. In addition, methods of indirect immunofluorescent (IIF) staining using specific antibodies are crucial to these observations. However, despite numerous reports about IIF protocols, few discussed in detail problems of specific centromere-kinetochore proteins.(1-4) Here we report optimized protocols to stain endogenous centromere-kinetochore proteins in human cells by using paraformaldehyde fixation and IIF staining. Furthermore, we report protocols to detect Flag-tagged exogenous CENP-A proteins in human cells subjected to acetone or methanol fixation. These methods are useful in detecting and quantifying endogenous centromere-kinetochore proteins and Flag-tagged CENP-A proteins, including those in human cells.
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Affiliation(s)
- Yohei Niikura
- Center for Childhood Cancer and Blood Diseases, Nationwide Children's Hospital
| | - Katsumi Kitagawa
- Center for Childhood Cancer and Blood Diseases, Nationwide Children's Hospital;
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Hu ZB, Liao XH, Xu ZY, Yang X, Dong C, Jin AM, Lu H. PLK2 phosphorylates and inhibits enriched TAp73 in human osteosarcoma cells. Cancer Med 2015; 5:74-87. [PMID: 26625870 PMCID: PMC4708894 DOI: 10.1002/cam4.558] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 09/12/2015] [Accepted: 09/14/2015] [Indexed: 01/01/2023] Open
Abstract
TAp73, a member of the p53 tumor suppressor family, can substitute for p53 function, especially in p53‐null and p53‐mutant cells. However, TAp73 enrichment and phosphorylation change its transcriptional activity. Previously, we found that the antitumor function of TAp73 was reactivated by dephosphorylation. Polo‐like kinase 2 (PLK2) plays an important role in bone development. Using a biological information database and phosphorylation prediction software, we hypothesized that PLK2 phosphorylates TAp73 and inhibits TAp73 function in osteosarcomas. Actually,we determined that PLK2 physically binds to and phosphorylates TAp73 when TAp73 protein abundance is up‐regulated by cisplatin. PLK2‐phosphorylated TAp73 at residue Ser48 within the TA domain; phosphorylation of TAp73 was abolished by mutating this residue. Moreover, PLK2 inhibition combined with cisplatin treatment in osteosarcoma Saos2 cells up‐regulated p21 and puma mRNA expression to a greater extent than cisplatin treatment alone. Inhibiting PLK2 in TAp73‐enriched Saos2 cells resulted in inhibited cell proliferation, increased apoptosis, G1 phase arrest, and decreased cell invasion. However, these changes did not occur in TAp73 knockdown Saos2 cells. In conclusion, these findings reveal a novel PLK2 function in the phosphorylation of TAp73, which prevents TAp73 activity in osteosarcoma cells. Thereby, this research provides an insight into the clinical treatment of malignant tumors overexpressing TAp73.
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Affiliation(s)
- Zheng Bo Hu
- Department of Orthopedics, Zhu Jiang Hospital of Southern Medical University, Guangzhou, Guangdong, 510280, China
| | - Xiao Hong Liao
- The State Key Laboratory of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, 510280, China
| | - Zun Ying Xu
- Department of Orthopedics, Zhu Jiang Hospital of Southern Medical University, Guangzhou, Guangdong, 510280, China
| | - Xiao Yang
- Department of Orthopedics, Zhu Jiang Hospital of Southern Medical University, Guangzhou, Guangdong, 510280, China
| | - Chao Dong
- Department of Orthopedics, Zhu Jiang Hospital of Southern Medical University, Guangzhou, Guangdong, 510280, China
| | - An Min Jin
- Department of Orthopedics, Zhu Jiang Hospital of Southern Medical University, Guangzhou, Guangdong, 510280, China
| | - Hai Lu
- Department of Orthopaedics, The Third Affiliated Hospital of Southern Medical University, Academy of Orthopedics, Guangzhou, Guangdong, 510665, China
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Hu Z, Xu Z, Liao X, Yang X, Dong C, Luk K, Jin A, Lu H. Polo-like kinase 2 acting as a promoter in human tumor cells with an abundance of TAp73. Onco Targets Ther 2015; 8:3475-88. [PMID: 26640387 PMCID: PMC4662374 DOI: 10.2147/ott.s90302] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Background TAp73, a member of the p53 tumor suppressor family, is frequently overexpressed in malignant tumors in humans. TAp73 abundance and phosphorylation modification result in variations in transcriptional activity. In a previous study, we found that the antitumor function of TAp73 was reactivated by dephosphorylation in head and neck squamous cell carcinomas. Polo-like kinase 2 (PLK2) displayed a close relationship with the p53 family in affecting the fate of cells. Herein, we investigate the hypothesis that PLK2 phosphorylates TAp73 and inhibits TAp73 function. Materials and methods Head and neck squamous cell carcinoma cell lines and osteosarcoma cell lines were used as natural models of the different expression levels of TAp73. Phosphorylation predictor software Scansite 3.0 and the predictor GPS-polo 1.0 were used to analyze the phosphorylation sites. Coimmunoprecipitation, phosphor-tag Western blot, metabolic labeling, and indirect immunofluorescence assays were used to determine the interactions between PLK2 and TAp73. TAp73 activity was assessed by Western blot and reverse transcription polymerase chain reaction, which we used to detect P21 and PUMA, both downstream genes of TAp73. The physiological effects of PLK2 cross talk with TAp73 on cell cycle progress and apoptosis were observed by flow cytometry and terminal deoxynucleotidyl transferase dUTP nick end labeling assays. Results PLK2 binds to and phosphorylates TAp73. PLK2 phosphorylates TAp73 at residue Ser48 and prohibits TAp73 translocation to the nucleus. Additionally, PLK2 inhibition combined with a DNA-damaging drug upregulated p21 and PUMA mRNA expression to a greater extent than DNA-damaging drug treatment alone. Inhibiting PLK2 in TAp73-enriched cells strengthened the effects of the DNA-damaging drug on both G1 phase arrest and apoptosis. Pretreatment with TAp73-siRNA weakened these effects. Conclusion These findings reveal a novel PLK2 function (catalyzed phosphorylation of TAp73) which suppresses TAp73 functions. PLK2 promotes the survival of human tumor cells, a novel insight into the workings of malignant tumors characterized by TAp73 overexpression, and one that could speed the development of therapies.
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Affiliation(s)
- ZhengBo Hu
- Department of Orthopedics, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - ZunYing Xu
- Department of Orthopedics, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - XiaoHong Liao
- The State Key Laboratory of Respiratory Diseases, the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, People's Republic of China
| | - Xiao Yang
- Department of Orthopedics, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - Cao Dong
- Department of Orthopedics, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - KuaDi Luk
- Department of Orthopedics and Traumatology, The University of Hong Kong, Hong Kong, SAR, People's Republic of China
| | - AnMin Jin
- Department of Orthopedics, Zhujiang Hospital of Southern Medical University, Guangzhou, Guangdong, People's Republic of China
| | - Hai Lu
- Department of Orthopedics, the Third Affiliated Hospital of the Southern Medical University, Guangzhou, Guangdong, People's Republic of China ; Academy of Orthopedics, Guangdong Province, People's Republic of China
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The oncogenic role of the cochaperone Sgt1. Oncogenesis 2015; 4:e149. [PMID: 25985210 PMCID: PMC4450263 DOI: 10.1038/oncsis.2015.12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 03/24/2015] [Accepted: 03/30/2015] [Indexed: 12/14/2022] Open
Abstract
Sgt1/Sugt1, a cochaperone of Hsp90, is involved in several cellular activities including Cullin E3 ubiqutin ligase activity. The high level of Sgt1 expression in colorectal and gastric tumors suggests that Sgt1 is involved in tumorigenesis. Here, we report that Sgt1 is overexpressed in colon, breast and lung tumor tissues and in Ewing sarcoma and rhabdomyosarcoma xenografts. We also found that Sgt1 heterozygous knockout resulted in suppressed Hras-mediated transformation in vitro and tumor formation in p53−/− mouse embryonic fibroblast cells and significantly increased survival of p53−/− mice. Moreover, depletion of Sgt1 inhibited the growth of Ewing sarcoma and rhabdomyosarcoma cells and destabilized EWS-FLI1 and PAX3-FOXO1 oncogenic fusion proteins, respectively, which are required for cellular growth. Our results suggest that Sgt1 contributes to cancer development by stabilizing oncoproteins and that Sgt1 is a potential therapeutic target.
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Zhu S, Jing R, Yang Y, Huang Y, Wang X, Leng Y, Xi J, Wang G, Jia W, Kang J. A motif from Lys216 to Lys222 in human BUB3 protein is a nuclear localization signal and critical for BUB3 function in mitotic checkpoint. J Biol Chem 2015; 290:11282-92. [PMID: 25814666 DOI: 10.1074/jbc.m114.598029] [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: 11/19/2014] [Indexed: 11/06/2022] Open
Abstract
Human BUB3 is a key mitotic checkpoint factor that recognizes centromeric components and recruits other mitotic checkpoint molecules to the unattached kinetochore. The key amino acid residues responsible for its localization are not yet defined. In this study, we identified a motif from Lys(216) to Lys(222) in BUB3 as its nuclear localization signal. A BUB3 mutant with deletion of this motif (Del216-222) was found to localize to both the cytoplasm and the nucleus, distinct from the exclusively nuclear distribution of wild-type BUB3. Further analysis revealed that residues Glu(213), Lys(216), Lys(217), Lys(218), Tyr(219), and Phe(221), but not Lys(222), contribute to nuclear localization. Interestingly, the nuclear localization signal was also critical for the kinetochore localization of BUB3. The deletion mutant Del216-222 and a subtle mutant with four residue changes in this region (E213Q/K216E/K217E/K218E (QE)) did not localize to the kinetochore efficiently or mediate mitotic checkpoint arrest. Protein interaction data suggested that the QE mutant was able to interact with BUB1, MAD2, and BubR1 but that its association with the centromeric components CENP-A and KNL1 was impaired. A motif from Leu(61) to Leu(65) in CENP-A was found to be involved in the association of BUB3 and CENP-A in cells; however, further assays suggested that CENP-A does not physically interact with BUB3 and does not affect BUB3 localization. Our findings help to dissect the mechanisms of BUB3 in mitotic checkpoint signaling.
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Affiliation(s)
- Songcheng Zhu
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
| | - Ruiqi Jing
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
| | - Yiwei Yang
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
| | - Yitong Huang
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
| | - Xin Wang
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
| | - Ye Leng
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
| | - Jiajie Xi
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
| | - Guiying Wang
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
| | - Wenwen Jia
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
| | - Jiuhong Kang
- From the Clinical and Translational Research Center of Shanghai First Maternity and Infant Hospital, Shanghai Key Laboratory of Signaling and Disease Research at School of Life Science and Technology, Tongji University, 1239 Si-ping Road, Shanghai 200092, China
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13
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Niikura Y, Kitagawa R, Ogi H, Abdulle R, Pagala V, Kitagawa K. CENP-A K124 Ubiquitylation Is Required for CENP-A Deposition at the Centromere. Dev Cell 2015; 32:589-603. [PMID: 25727006 PMCID: PMC4374629 DOI: 10.1016/j.devcel.2015.01.024] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Revised: 10/24/2014] [Accepted: 01/21/2015] [Indexed: 11/23/2022]
Abstract
CENP-A is a centromere-specific histone H3 variant that epigenetically determines centromere identity to ensure kinetochore assembly and proper chromosome segregation, but the precise mechanism of its specific localization within centromeric heterochromatin remains obscure. We have discovered that CUL4A-RBX1-COPS8 E3 ligase activity is required for CENP-A ubiquitylation on lysine 124 (K124) and CENP-A centromere localization. A mutation of CENP-A, K124R, reduces interaction with HJURP (a CENP-A-specific histone chaperone) and abrogates localization of CENP-A to the centromere. Addition of monoubiquitin is sufficient to restore CENP-A K124R to centromeres and the interaction with HJURP, indicating that "signaling" ubiquitylation is required for CENP-A loading at centromeres. The CUL4A-RBX1 complex is required for loading newly synthesized CENP-A and maintaining preassembled CENP-A at centromeres. Thus, CENP-A K124R ubiquitylation, mediated by the CUL4A-RBX1-COPS8 complex, is essential for CENP-A deposition at the centromere.
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Affiliation(s)
- Yohei Niikura
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Risa Kitagawa
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Hiroo Ogi
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Rashid Abdulle
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA
| | - Vishwajeeth Pagala
- Hartwell Center for Bioinformatics and Biotechnology, St. Jude Children's Research Hospital, 262 Danny Thomas Place, Memphis, TN 38105, USA
| | - Katsumi Kitagawa
- Center for Childhood Cancer and Blood Diseases, The Research Institute at Nationwide Children's Hospital, 700 Children's Drive, Columbus, OH 43205, USA; Department of Pediatrics, College of Medicine, The Ohio State University, 700 Children's Drive, Columbus, OH 43205, USA.
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14
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Logotheti S, Pavlopoulou A, Galtsidis S, Vojtesek B, Zoumpourlis V. Functions, divergence and clinical value of TAp73 isoforms in cancer. Cancer Metastasis Rev 2014; 32:511-34. [PMID: 23592418 DOI: 10.1007/s10555-013-9424-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The p73 gene encodes the tumour suppressive full-length TAp73 and N-terminal-truncated DNp73 isoforms that act as dominant negative inhibitors of TAp73. The overall effect of p73 in oncogenesis is thought to depend on the TAp73 to DNp73 isoforms' ratio. TAp73 isoforms include a number of C-terminal variants as a result of alternative splicing in 3'-end. TAp73 isoforms protect cells from oncogenic alterations in a multifaceted way since they are implicated in the suppression of all demonstrated hallmarks and enabling characteristics of cancer. Their best established role is in apoptosis, a process which seems to be differently affected by each TAp73 C-terminal variant. Based on previous findings and our thorough bioinformatics analysis, we highlight that TAp73 variants are functionally non-equivalent, since they present major differences in their transactivation efficiencies, protein interactions, response to DNA damage and apoptotic effects that are attributable to the primary structure of their C terminus. In this review, we summarise these differences and we unveil the link between crucial C-terminal motifs/residues and the oncosuppressive potential of TAp73 isoforms, emphasising on the importance of considering C terminus during the development of p73-based anticancer biologics.
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Affiliation(s)
- Stella Logotheti
- Unit of Biomedical Applications, Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, 48 Vas. Constantinou Ave, 11635, Athens, Greece
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15
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Costa O, Schneider P, Coquet L, Chan P, Penther D, Legrand E, Jouenne T, Vasse M, Vannier JP. Proteomic profile of pre - B2 lymphoblasts from children with acute lymphoblastic leukemia (ALL) in relation with the translocation (12; 21). Clin Proteomics 2014; 11:31. [PMID: 25136288 PMCID: PMC4128613 DOI: 10.1186/1559-0275-11-31] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2014] [Accepted: 07/14/2014] [Indexed: 12/12/2022] Open
Abstract
Background Until now, the major prognostic factors for pediatric acute lymphoblastic leukemia (ALL), age, white blood cell count and chromosomal alterations are initially taken into account for the risk stratification of patients. In the light of protein marker studies to classify subtypes of Acute Myeloblastic Leukemia efficiently, we have compared the lymphoblastes proteome in Childhood ALL in accordance with the presence of t(12;21), indicator of good prognosis, usually. Methods Protein expression in pre-B2 lymphoblastic cells, collected from residual bone marrow cells after diagnostic procedures, was analyzed using two dimensional gel electrophoresis protocol. Protein spots whose average normalized volumes were statistically different in the two patients groups (n = 13; student t test p < 0.01), were excised. Tryptic peptides were then analyzed using a nano-LC1200 system coupled to a 6340 Ion Trap mass spectrometer equipped with a HPLC-chip cube interface. The tandem mass spectrometry peak lists extracted using the DataAnalysis program, were compared with the protein database Mascot Daemon. Results We focused on twelve spots corresponding to sixteen identified candidate proteins among the 26 found differentially expressed (p ≤ 0.05) regarding the presence of t(12;21). Among over expressed proteins, two proteins were implicated in cellular growth arrest (i.e. calponine 2, p ≤ 0.001 and phosphatidylinositol transfer protein beta, p ≤ 0.001) in accordance with good prognosis, while two other proteins favored cell cycle proliferation (i.e. methionine adenosyl transferase 2β, p ≤ 0.005 and heterogeneous nuclear ribonucleo-proteins A2 p ≤ 0.01) and could therefore be good marker candidates of aggressiveness. Level of expression of proteasome subunit beta type-2 (p ≤ 0.01) and protein casein kinase 2α (p ≤ 0.01) which both favored apoptosis, deubiquitinating enzyme OTUB1 (p ≤ 0.05) and MLL septin-like fusion protein MSF-B, septin 9 i4 (p ≤ 0.01) were in accord with a good prognosis related to t(12;21) lymphoblasts. Conclusion By drawing up the protein map of leukemic cells, these new data identified marker candidates of leukemic aggressiveness and new t(12;21) patients subgroups. These preliminary results will be in the near future confirmed by using a larger sample of pre-B2 childhood ALLs from national lymphoblastic cell collections.
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Affiliation(s)
- Odile Costa
- Laboratoire MERCI, Faculté de Médecine et de Pharmacie de Rouen, 123 boulevard Gambetta, Rouen, Cedex 76183, France
| | - Pascale Schneider
- Laboratoire MERCI, Faculté de Médecine et de Pharmacie de Rouen, 123 boulevard Gambetta, Rouen, Cedex 76183, France ; Service d'Immuno-Hématologie Onco-pédiatrique du CHRU de Rouen, Hôpital Charles Nicolle, Rouen 76031, France
| | - Laurent Coquet
- PISSARO Proteomic facility, (IRIB), U-Rouen, Mont Saint- Aignan, France ; CNRS UMR 6270, Team « Biofilms, Résistance, Interactions Cellules-Surfaces », U-Rouen, Mont Saint-Aignan, France
| | - Philippe Chan
- PISSARO Proteomic facility, (IRIB), U-Rouen, Mont Saint- Aignan, France
| | - Dominique Penther
- Laboratoire de Cytogénétique, Centre Henri Becquerel, Rouen 76000, France
| | - Elisabeth Legrand
- Laboratoire MERCI, Faculté de Médecine et de Pharmacie de Rouen, 123 boulevard Gambetta, Rouen, Cedex 76183, France
| | - Thierry Jouenne
- PISSARO Proteomic facility, (IRIB), U-Rouen, Mont Saint- Aignan, France ; CNRS UMR 6270, Team « Biofilms, Résistance, Interactions Cellules-Surfaces », U-Rouen, Mont Saint-Aignan, France
| | - Marc Vasse
- Laboratoire MERCI, Faculté de Médecine et de Pharmacie de Rouen, 123 boulevard Gambetta, Rouen, Cedex 76183, France
| | - Jean-Pierre Vannier
- Laboratoire MERCI, Faculté de Médecine et de Pharmacie de Rouen, 123 boulevard Gambetta, Rouen, Cedex 76183, France ; Service d'Immuno-Hématologie Onco-pédiatrique du CHRU de Rouen, Hôpital Charles Nicolle, Rouen 76031, France
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16
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Abstract
P73 is a member of the p53 transcription factors family with a prominent role in neurobiology, affecting brain development as well as controlling neuronal survival. Accordingly, p73 has been identified as key player in many age-related neurodegenerative diseases, such as Alzheimer's disease, neuroAIDS and Niemann-Pick type C disease. Here we investigate possible correlations of p73 with Parkinson disease. Tyrosine hydroxylase is a crucial player in Parkinson disease being the enzyme necessary for dopamine synthesis. In this work we show that levels of tyrosine hydroxylase can be influenced by p73. We also demonstrate that p73 can protect against tyrosine hydroxylase depletion in an in vitro model of Parkinson disease.
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Affiliation(s)
- Francesca Grespi
- Medical Research Council, Toxicology Unit, Leicester University, Leicester LE1 9HN, UK
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17
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Zasadil LM, Britigan EMC, Weaver BA. 2n or not 2n: Aneuploidy, polyploidy and chromosomal instability in primary and tumor cells. Semin Cell Dev Biol 2013; 24:370-9. [PMID: 23416057 DOI: 10.1016/j.semcdb.2013.02.001] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2012] [Revised: 01/28/2013] [Accepted: 02/06/2013] [Indexed: 12/12/2022]
Abstract
Mitotic defects leading to aneuploidy have been recognized as a hallmark of tumor cells for over 100 years. Current data indicate that ∼85% of human cancers have missegregated chromosomes to become aneuploid. Some maintain a stable aneuploid karyotype, while others consistently missegregate chromosomes over multiple divisions due to chromosomal instability (CIN). Both aneuploidy and CIN serve as markers of poor prognosis in diverse human cancers. Despite this, aneuploidy is generally incompatible with viability during development, and some aneuploid karyotypes cause a proliferative disadvantage in somatic cells. In vivo, the intentional introduction of aneuploidy can promote tumors, suppress them, or do neither. Here, we summarize current knowledge of the effects of aneuploidy and CIN on proliferation and cell death in nontransformed cells, as well as on tumor promotion, suppression, and prognosis.
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Affiliation(s)
- Lauren M Zasadil
- Department of Cell and Regenerative Biology, University of Wisconsin, Madison, WI 53705, USA
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18
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Grespi F, Amelio I, Tucci P, Annicchiarico-Petruzzelli M, Melino G. Tissue-specific expression of p73 C-terminal isoforms in mice. Cell Cycle 2012; 11:4474-83. [PMID: 23159862 PMCID: PMC3552929 DOI: 10.4161/cc.22787] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
p73 is a p53 family transcription factor. Due to the presence in the 5' flanking region of two promoters, there are two N-terminal variants, TAp73, which retains a fully active transactivation domain (TA), and ΔNp73, in which the N terminus is truncated. In addition, extensive 3' splicing gives rise to at least seven distinctive isoforms; TAp73-selective knockout highlights its role as a regulator of cell death, senescence and tumor suppressor. ΔNp73-selective knockout, on the other hand, highlights anti-apoptotic function of ΔNp73 and its involvement in DNA damage response. In this work, we investigated the expression pattern of murine p73 C-terminal isoforms. By using a RT-PCR approach, we were able to detect mRNAs of all the C-terminal isoforms described in humans. We characterized their in vivo expression profile in mouse organs and in different mouse developmental stages. Finally, we investigated p73 C-terminal expression profile following DNA damage, ex vivo after primary cultures treatment and in vivo after systemic administration of cytotoxic compounds. Overall, our study first elucidates spatio-temporal expression of mouse p73 isoforms and provides novel insights on their expression-switch under triggered conditions.
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Affiliation(s)
- Francesca Grespi
- Medical Research Council, Toxicology Unit, Leicester University, Leicester, UK
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19
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Abstract
Mitosis is tightly regulated and any errors in this process often lead to aneuploidy, genomic instability, and tumorigenesis. Deregulation of mitotic kinases is significantly associated with improper cell division and aneuploidy. Because of their importance during mitosis and the relevance to cancer, mitotic kinase signaling has been extensively studied over the past few decades and, as a result, several mitotic kinase inhibitors have been developed. Despite promising preclinical results, targeting mitotic kinases for cancer therapy faces numerous challenges, including safety and patient selection issues. Therefore, there is an urgent need to better understand the molecular mechanisms underlying mitotic kinase signaling and its interactive network. Increasing evidence suggests that tumor suppressor p53 functions at the center of the mitotic kinase signaling network. In response to mitotic spindle damage, multiple mitotic kinases phosphorylate p53 to either activate or deactivate p53-mediated signaling. p53 can also regulate the expression and function of mitotic kinases, suggesting the existence of a network of mutual regulation, which can be positive or negative, between mitotic kinases and p53 signaling. Therefore, deciphering this regulatory network will provide knowledge to overcome current limitations of targeting mitotic kinases and further improve the results of targeted therapy.
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20
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Rufini A, Agostini M, Grespi F, Tomasini R, Sayan BS, Niklison-Chirou MV, Conforti F, Velletri T, Mastino A, Mak TW, Melino G, Knight RA. p73 in Cancer. Genes Cancer 2011; 2:491-502. [PMID: 21779517 DOI: 10.1177/1947601911408890] [Citation(s) in RCA: 117] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
p73 is a tumor suppressor belonging to the p53 family of transcription factors. Distinct isoforms are transcribed from the p73 locus. The use of 2 promoters at the N-terminus allows the expression of an isoform containing (TAp73) or not containing (ΔNp73) a complete N-terminal transactivation domain, with the latter isoform capable of a dominant negative effect over the former. In addition, both N-terminal variants are alternatively spliced at the C-terminus. TAp73 is a bona fide tumor suppressor, being able to induce cell death and cell cycle arrest; conversely, ΔNp73 shows oncogenic properties, inhibiting TAp73 and p53 functions. Here, we discuss the latest findings linking p73 to cancer. The generation of isoform specific null mice has helped in dissecting the contribution of TA versus ΔNp73 isoforms to tumorigenesis. The activity of both isoforms is regulated transcriptionally and by posttranslational modification. p73 dysfunction, particularly of TAp73, has been associated with mitotic abnormalities, which may lead to polyploidy and aneuploidy and thus contribute to tumorigenesis. Although p73 is only rarely mutated in cancer, the tumor suppressor actions of TAp73 are inhibited by mutant p53, a finding that has important implications for cancer therapy. Finally, we discuss the expression and role of p73 isoforms in human cancer, with a particular emphasis on the neuroblastoma cancer model. Broadly, the data support the hypothesis that the ratio between TAp73 and ΔNp73 is crucial for tumor progression and therapeutic response.
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Affiliation(s)
- Alessandro Rufini
- Toxicology Unit, Medical Research Council, Leicester, LE1 9HN, United Kingdom
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21
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p53: guardian of ploidy. Mol Oncol 2011; 5:315-23. [PMID: 21852209 DOI: 10.1016/j.molonc.2011.07.007] [Citation(s) in RCA: 145] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 07/21/2011] [Accepted: 07/21/2011] [Indexed: 11/20/2022] Open
Abstract
Aneuploidy, often preceded by tetraploidy, is one of the hallmarks of solid tumors. Indeed, both aneuploidy and tetraploidy are oncogenic occurrences that are sufficient to drive neoplastic transformation and cancer progression. True to form, the tumor suppressor p53 obstructs propagation of these dangerous chromosomal events by either instigating irreversible cell cycle arrest or apoptosis. The tumor suppressor Lats2, along with other tumor inhibitory proteins such as BRCA1/2 and BubR1, are central to p53-dependent elimination of tetraploid cells. Not surprisingly, these proteins are frequently inactivated or downregulated in tumors, synergizing with p53 inactivation to establish an atmosphere of "tolerance" for a non-diploid state.
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22
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Abstract
Chromosome fragmentation (C-Frag) is a newly identified MCD (mitotic cell death), distinct from apoptosis and MC (mitotic catastrophe). As different molecular mechanisms can induce C-Frag, we hypothesize that the general mechanism of its induction is a system response to cellular stress. A clear link between C-Frag and diverse system stresses generated from an array of molecular mechanisms is shown. Centrosome amplification, which is also linked to diverse mechanisms of stress, is shown to occur in association with C-Frag. This led to a new model showing that diverse stresses induce common, MCD. Specifically, different cellular stresses target the integral chromosomal machinery, leading to system instability and triggering of MCD by C-Frag. This model of stress-induced cell death is also applicable to other types of cell death. The current study solves the previously confusing relationship between the diverse molecular mechanisms of chromosome pulverization, suggesting that incomplete C-Frag could serve as the initial event responsible for forms of genome chaos including chromothripsis. In addition, multiple cell death types are shown to coexist with C-Frag and it is more dominant than apoptosis at lower drug concentrations. Together, this study suggests that cell death is a diverse group of highly heterogeneous events that are linked to stress-induced system instability and evolutionary potential.
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Agarwal N, Tochigi Y, Adhikari AS, Cui S, Cui Y, Iwakuma T. MTBP plays a crucial role in mitotic progression and chromosome segregation. Cell Death Differ 2011; 18:1208-19. [PMID: 21274008 DOI: 10.1038/cdd.2010.189] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Murine double minute 2 (MDM2) binding protein (MTBP) has been implicated in tumor cell proliferation, but the underlying mechanisms remain unclear. The results of MTBP expression analysis during cell cycle progression demonstrated that MTBP protein was rapidly degraded during mitosis. Immunofluorescence studies revealed that a portion of MTBP was localized at the kinetochores during prometaphase. MTBP overexpression delayed mitotic progression from nuclear envelope breakdown (NEB) to anaphase onset and induced abnormal chromosome segregation such as lagging chromosomes, chromosome bridges, and multipolar chromosome segregation. Conversely, MTBP downmodulation caused an abbreviated metaphase and insufficient mitotic arrest, resulting in abnormal chromosome segregation, aneuploidy, decreased cell proliferation, senescence, and cell death, similar to that of Mad2 (mitotic arrest-deficient 2) downmodulation. Furthermore, MTBP downmodulation inhibited the accumulation of Mad1 and Mad2, but not BubR1 (budding uninhibited by benzimidazoles related 1), on the kinetochores, whereas MTBP overexpression inhibited the release of Mad2 from the metaphase kinetochores. These results may imply that MTBP has an important role in recruiting and/or retaining the Mad1/Mad2 complex at the kinetochores during prometaphase, but its degradation is required for silencing the mitotic checkpoint. Together, this study indicates that MTBP has a crucial role in proper mitotic progression and faithful chromosome segregation, providing new insights into regulation of the mitotic checkpoint.
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Affiliation(s)
- N Agarwal
- Department of Genetics, Louisiana State University Health Sciences Center, New Orleans, LA 70112, USA
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