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Zhang C, Ni C, Lu H. Polo-Like Kinase 2: From Principle to Practice. Front Oncol 2022; 12:956225. [PMID: 35898867 PMCID: PMC9309260 DOI: 10.3389/fonc.2022.956225] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Accepted: 06/14/2022] [Indexed: 11/21/2022] Open
Abstract
Polo-like kinase (PLK) 2 is an evolutionarily conserved serine/threonine kinase that shares the n-terminal kinase catalytic domain and the C-terminal Polo Box Domain (PBD) with other members of the PLKs family. In the last two decades, mounting studies have focused on this and tried to clarify its role in many aspects. PLK2 is essential for mitotic centriole replication and meiotic chromatin pairing, synapsis, and crossing-over in the cell cycle; Loss of PLK2 function results in cell cycle disorders and developmental retardation. PLK2 is also involved in regulating cell differentiation and maintaining neural homeostasis. In the process of various stimuli-induced stress, including oxidative and endoplasmic reticulum, PLK2 may promote survival or apoptosis depending on the intensity of stimulation and the degree of cell damage. However, the role of PLK2 in immunity to viral infection has been studied far less than that of other family members. Because PLK2 is extensively and deeply involved in normal physiological functions and pathophysiological mechanisms of cells, its role in diseases is increasingly being paid attention to. The effect of PLK2 in inhibiting hematological tumors and fibrotic diseases, as well as participating in neurodegenerative diseases, has been gradually recognized. However, the research results in solid organ tumors show contradictory results. In addition, preliminary studies using PLK2 as a disease predictor and therapeutic target have yielded some exciting and promising results. More research will help people better understand PLK2 from principle to practice.
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Affiliation(s)
- Chuanyong Zhang
- Hepatobiliary Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Key Laboratory of Liver Transplantation, Chinese Academy of Medical Sciences, Nanjing, China
| | - Chuangye Ni
- Hepatobiliary Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Key Laboratory of Liver Transplantation, Chinese Academy of Medical Sciences, Nanjing, China
| | - Hao Lu
- Hepatobiliary Center, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China
- Key Laboratory of Liver Transplantation, Chinese Academy of Medical Sciences, Nanjing, China
- *Correspondence: Hao Lu,
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Xu L, Qu JL, Song N, Zhang LY, Zeng X, Che XF, Hou KZ, Shi S, Feng ZY, Qu XJ, Liu YP, Teng YE. Biological and clinical significance of flap endonuclease‑1 in triple‑negative breast cancer: Support of metastasis and a poor prognosis. Oncol Rep 2020; 44:2443-2454. [PMID: 33125141 PMCID: PMC7610327 DOI: 10.3892/or.2020.7812] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Accepted: 07/27/2020] [Indexed: 12/17/2022] Open
Abstract
Flap endonuclease‑1 (FEN1), a structure‑specific nuclease participating in DNA replication and repair processes, has been confirmed to promote the proliferation and drug resistance of tumor cells. However, the biological functions of FEN1 in cancer cell migration and invasion have not been defined. In the present study, using online database analysis and immunohistochemistry of the specimens, it was found that FEN1 expression was associated with a highly invasive triple‑negative breast cancer (TNBC) subtype in both breast cancer samples from the Oncomine database and from patients recruited into the study. Furthermore, FEN1 was an important biomarker of lymph node metastasis and poor prognosis in patients with TNBC. FEN1 promoted migration of TNBC cell lines and FEN1 knockdown reduced the number of spontaneous lung metastasis in vivo. Ingenuity Pathway Analysis of FEN1‑related transcripts in 198 patients with TNBC demonstrated that the polo‑like kinase family may be the downstream target of FEN1. PLK4 was further identified as a critical target of FEN1 mediating TNBC cell migration, by regulating actin cytoskeleton rearrangement. The results of the present study validate FEN1 as a therapeutic target in patients with TNBC and revealed a new role for FEN1 in regulating TNBC invasion and metastasis.
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Affiliation(s)
- Lu Xu
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Jing-Lei Qu
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Na Song
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Ling-Yun Zhang
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xue Zeng
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Xiao-Fang Che
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Ke-Zuo Hou
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Sha Shi
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Zu-Ying Feng
- Boz Life Science Research and Teaching Institute, San Diego, CA 92109, USA
| | - Xiu-Juan Qu
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yun-Peng Liu
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
| | - Yue-E Teng
- Department of Medical Oncology, The First Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
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Ling H, Peng L, Wang J, Rahhal R, Seto E. Histone Deacetylase SIRT1 Targets Plk2 to Regulate Centriole Duplication. Cell Rep 2019; 25:2851-2865.e3. [PMID: 30517871 DOI: 10.1016/j.celrep.2018.11.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 09/04/2018] [Accepted: 11/02/2018] [Indexed: 11/17/2022] Open
Abstract
The protein deacetylase SIRT1 (Sirtuin 1) regulates many cellular processes, including cell-cycle progression, DNA damage response, and metabolism. Although the centrosome is a key regulator of cell-cycle progression and genome stability, little is known concerning SIRT1 controlled centrosome-associated events. Here we report that the centrosome protein Plk2 is acetylated and undergoes deacetylation by SIRT1. Acetylation protects Plk2 from ubiquitination, and SIRT1-mediated deacetylation promotes ubiquitin-dependent degradation of Plk2. SIRT1 controls centriole duplication by temporally modulating centrosomal Plk2 levels. AURKA phosphorylates SIRT1 and promotes the SIRT1-Plk2 interaction in mitosis. In early-mid G1, phosphorylated SIRT1 deacetylates and promotes Plk2 degradation. In late G1, SIRT1 is hypophosphorylated and its affinity to Plk2 is decreased, resulting in a rapid accumulation of centrosomal Plk2, which contributes to the timely initiation of centriole duplication. Collectively, our findings uncover a critical role of SIRT1 in centriole duplication and provide a mechanistic insight into SIRT1-mediated centrosome-associated functions.
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Affiliation(s)
- Hongbo Ling
- George Washington University Cancer Center, Washington, DC 20052, USA; Department of Biochemistry & Molecular Medicine, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA
| | - Lirong Peng
- George Washington University Cancer Center, Washington, DC 20052, USA; Department of Biochemistry & Molecular Medicine, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA
| | - Jianbo Wang
- Department of Oncology, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Raneen Rahhal
- George Washington University Cancer Center, Washington, DC 20052, USA; Department of Biochemistry & Molecular Medicine, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA
| | - Edward Seto
- George Washington University Cancer Center, Washington, DC 20052, USA; Department of Biochemistry & Molecular Medicine, The George Washington University School of Medicine & Health Sciences, Washington, DC 20052, USA.
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Pranatharthi A, Thomas P, Udayashankar AH, Bhavani C, Suresh SB, Krishna S, Thatte J, Srikantia N, Ross CR, Srivastava S. RhoC regulates radioresistance via crosstalk of ROCK2 with the DNA repair machinery in cervical cancer. JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH : CR 2019; 38:392. [PMID: 31488179 PMCID: PMC6729006 DOI: 10.1186/s13046-019-1385-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 08/15/2019] [Indexed: 01/06/2023]
Abstract
Background Radioresistance remains a challenge to the successful treatment of various tumors. Intrinsic factors like alterations in signaling pathways regulate response to radiation. RhoC, which has been shown to modulate several tumor phenotypes has been investigated in this report for its role in radioresistance. In vitro and clinical sample-based studies have been performed to understand its contribution to radiation response in cervical cancer and this is the first report to establish the role of RhoC and its effector ROCK2 in cervical cancer radiation response. Methods Biochemical, transcriptomic and immunological approaches including flow cytometry and immunofluorescence were used to understand the role of RhoC and ROCK2. RhoC variants, siRNA and chemical inhibitors were used to alter the function of RhoC and ROCK2. Transcriptomic profiling was performed to understand the gene expression pattern of the cells. Live sorting using an intracellular antigen has been developed to isolate the cells for transcriptomic studies. Results Enhanced expression of RhoC conferred radioprotection on the tumor cells while inhibition of RhoC resulted in sensitization of cells to radiation. The RhoC overexpressing cells had a better DNA repair machinery as observed using transcriptomic analysis. Similarly, overexpression of ROCK2, protected tumor cells against radiation while its inhibition increased radiosensitivity in vitro. Further investigations revealed that ROCK2 inhibition abolished the radioresistance phenotype, conferred by RhoC on SiHa cells, confirming that it is a downstream effector of RhoC in this context. Additionally, transcriptional analysis of the live sorted ROCK2 high and ROCK2 low expressing SiHa cells revealed an upregulation of the DNA repair pathway proteins. Consequently, inhibition of ROCK2 resulted in reduced expression of pH2Ax and MRN complex proteins, critical to repair of double strand breaks. Clinical sample-based studies also demonstrated that ROCK2 inhibition sensitizes tumor cells to irradiation. Conclusions Our data primarily indicates that RhoC and ROCK2 signaling is important for the radioresistance phenotype in cervical cancer tumor cells and is regulated via association of ROCK2 with the proteins of DNA repair pathway involving pH2Ax, MRE11 and RAD50 proteins, partly offering insights into the mechanism of radioresistance in tumor cells. These findings highlight RhoC-ROCK2 signaling involvement in DNA repair and urge the need for development of these molecules as targets to alleviate the non-responsiveness of cervical cancer tumor cells to irradiation treatment. Electronic supplementary material The online version of this article (10.1186/s13046-019-1385-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Annapurna Pranatharthi
- National Centre for Biological Sciences (NCBS), Bangalore, 560065, India.,Rajiv Gandhi University of Health Sciences, Bangalore, 560041, India.,Translational and Molecular Biology Laboratory (TMBL), Department of Medicine, St. John's Medical College Hospital (SJMCH), Bangalore, 560034, India
| | - Pavana Thomas
- School of Integrative Health Sciences, The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, 560064, India.,Translational and Molecular Biology Laboratory (TMBL), St. John's Research Institute (SJRI), Bangalore, 560034, India
| | - Avinash H Udayashankar
- Department of Radiation Oncology, St John's Medical College Hospital (SJMCH), Bangalore, 560034, India
| | - Chandra Bhavani
- Translational and Molecular Biology Laboratory (TMBL), St. John's Research Institute (SJRI), Bangalore, 560034, India
| | - Srinag Bangalore Suresh
- Rajiv Gandhi University of Health Sciences, Bangalore, 560041, India.,Translational and Molecular Biology Laboratory (TMBL), Department of Medicine, St. John's Medical College Hospital (SJMCH), Bangalore, 560034, India
| | - Sudhir Krishna
- National Centre for Biological Sciences (NCBS), Bangalore, 560065, India
| | - Jayashree Thatte
- National Centre for Biological Sciences (NCBS), Bangalore, 560065, India
| | - Nirmala Srikantia
- Department of Radiation Oncology, St John's Medical College Hospital (SJMCH), Bangalore, 560034, India
| | - Cecil R Ross
- Rajiv Gandhi University of Health Sciences, Bangalore, 560041, India.,Translational and Molecular Biology Laboratory (TMBL), Department of Medicine, St. John's Medical College Hospital (SJMCH), Bangalore, 560034, India
| | - Sweta Srivastava
- Translational and Molecular Biology Laboratory (TMBL), Department of Transfusion Medicine and Immunohematology, St. John's Medical College Hospital (SJMCH), Bangalore, 560034, India. .,School of Integrative Health Sciences, The University of Trans-Disciplinary Health Sciences and Technology (TDU), Bangalore, 560064, India.
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POLQ Overexpression Is Associated with an Increased Somatic Mutation Load and PLK4 Overexpression in Lung Adenocarcinoma. Cancers (Basel) 2019; 11:cancers11050722. [PMID: 31137743 PMCID: PMC6562496 DOI: 10.3390/cancers11050722] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Revised: 05/16/2019] [Accepted: 05/22/2019] [Indexed: 01/23/2023] Open
Abstract
DNA Polymerase Theta (POLQ) is a DNA polymerase involved in error-prone translesion DNA synthesis (TLS) and error-prone repair of DNA double-strand breaks (DSBs). In the present study, we examined whether abnormal POLQ expression may be involved in the pathogenesis of lung adenocarcinoma (LAC). First, we found overexpression of POLQ at both the mRNA and protein levels in LAC, using data from the Cancer Genome Atlas (TCGA) database and by immunohistochemical analysis of our LAC series. POLQ overexpression was associated with an advanced pathologic stage and an increased total number of somatic mutations in LAC. When H1299 human lung cancer cell clones overexpressing POLQ were established and examined, the clones showed resistance to a DSB-inducing chemical in the clonogenic assay and an increased frequency of mutations in the supF forward mutation assay. Further analysis revealed that POLQ overexpression was also positively correlated with Polo Like Kinase 4 (PLK4) overexpression in LAC, and that PLK4 overexpression in the POLQ-overexpressing H1299 cells induced centrosome amplification. Finally, analysis of the TCGA data revealed that POLQ overexpression was associated with an increased somatic mutation load and PLK4 overexpression in diverse human cancers; on the other hand, overexpressions of nine TLS polymerases other than POLQ were associated with an increased somatic mutation load at a much lower frequency. Thus, POLQ overexpression is associated with advanced pathologic stage, increased somatic mutation load, and PLK4 overexpression, the last inducing centrosome amplification, in LAC, suggesting that POLQ overexpression is involved in the pathogenesis of LAC.
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Zhang RK, Wang P, Lu YC, Lang L, Wang L, Lee SC. Cadmium induces cell centrosome amplification via reactive oxygen species as well as endoplasmic reticulum stress pathway. J Cell Physiol 2019; 234:18230-18248. [DOI: 10.1002/jcp.28455] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 02/06/2019] [Accepted: 02/14/2019] [Indexed: 12/13/2022]
Affiliation(s)
- Rui Kai Zhang
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Pu Wang
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Yu Cheng Lu
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Lang Lang
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Lan Wang
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
| | - Shao Chin Lee
- Department of Biology, School of Life Sciences Shanxi University Taiyuan Shanxi People's Republic of China
- Department of Biology, School of Life Sciences Jiangsu Normal University Xuzhou Jiangsu People's Republic of China
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7
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He Y, Wang H, Yan M, Yang X, Shen R, Ni X, Chen X, Yang P, Chen M, Lu X, Shao G, Zhou X, Shao Q. High LIN28A and PLK4 co‑expression is associated with poor prognosis in epithelial ovarian cancer. Mol Med Rep 2018; 18:5327-5336. [PMID: 30365085 PMCID: PMC6236221 DOI: 10.3892/mmr.2018.9562] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 07/30/2018] [Indexed: 12/31/2022] Open
Abstract
Epithelial ovarian cancer (EOC) is the most lethal gynecological malignancy. LIN28 homolog A (LIN28A) is a RNA‑binding protein, which serves a fundamental role in cell development and pluripotency. Polo‑like kinase 4 (PLK4) is a member of the polo‑like kinase family, which primarily takes part in the mitotic regulation. Overexpression of LIN28A has been demonstrated in ovarian cancer; however, the expression of PLK4 and the correlation between the expression of LIN28A and PLK4 in EOC has not been discussed. In the present study, the mRNA and protein levels of LIN28A and PLK4 were evaluated by reverse transcription‑quantitative polymerase chain reaction and immunohistochemistry in ovarian tissues of patients. Results demonstrated significantly increased expression in EOC compared with benign epithelial ovarian tumors. High expression of LIN28A and PLK4 was detected at the advanced pathological stage. Furthermore, PLK4 expression was positively correlated with LIN28A (r=0.555; P=0.039). The median survival analysis of patients with EOC with LIN28A and PLK4 double positive expression was 14 months, compared with 30 months in single positive and 60 months in double negative patients by Kaplan‑Meier analysis (P<0.05). The expressions of LIN28A and PLK4 was elevated in different EOC cell lines compared to with a normal ovarian cell line. The 293T cells transfected with LIN28A plus a PLK4 plasmid were the fastest‑growing group. These results suggest that co‑expression of LIN28A and PLK4 may be associated with poor prognosis of EOC and could serve as promising prognostic biomarkers and therapeutic targets in EOC. LIN28A and PLK4 may be used along with traditional morphological and clinical characteristics for predicting prognosis.
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Affiliation(s)
- Yao He
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
- Department of Gynecology and Obstetrics, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212001, P.R. China
- Department of Obstetrics, Obstetrics and Gynecology Hospital Affiliated to Nanjing Medical University, Nanjing, Jiangsu 2100011, P.R. China
| | - Hui Wang
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, Zhenjiang, Jiangsu 212013, P.R. China
| | - Meina Yan
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, Zhenjiang, Jiangsu 212013, P.R. China
| | - Xinxin Yang
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, Zhenjiang, Jiangsu 212013, P.R. China
| | - Rong Shen
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, Zhenjiang, Jiangsu 212013, P.R. China
| | - Xiaoge Ni
- Department of Gynecology and Obstetrics, Affiliated People's Hospital of Jiangsu University, Zhenjiang, Jiangsu 212001, P.R. China
| | - Xiaokun Chen
- Department of Gynecology and Obstetrics, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212001, P.R. China
| | - Peifang Yang
- Department of Gynecology and Obstetrics, Affiliated Hospital of Jiangsu University, Zhenjiang, Jiangsu 212001, P.R. China
| | - Miao Chen
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
| | - Xiaodong Lu
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
| | - Genbao Shao
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
| | - Xiaoming Zhou
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
| | - Qixiang Shao
- Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang, Jiangsu 212013, P.R. China
- Jiangsu Key Laboratory of Medical Science and Laboratory Medicine, Zhenjiang, Jiangsu 212013, P.R. China
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Shakhov AS, Alieva IB. The Centrosome as the Main Integrator of Endothelial Cell Functional Activity. BIOCHEMISTRY (MOSCOW) 2017; 82:663-677. [PMID: 28601076 DOI: 10.1134/s0006297917060037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The centrosome is an intracellular structure of the animal cell responsible for organization of cytoplasmic microtubules. According to modern concepts, the centrosome is a very important integral element of the living cell whose functions are not limited to its ability to polymerize microtubules. The centrosome localization in the geometric center of the interphase cell, the high concentration of various regulatory proteins in this area, the centrosome-organized radial system of microtubules for intracellular transport by motor proteins, the centrosome involvement in the perception of external signals and their transmission - all these features make this cellular structure a unique regulation and distribution center managing dynamic morphology of the animal cell. In conjunction with the tissue-specific features of the centrosome structure, this suggests the direct involvement of the centrosome in execution of cell functions. This review discusses the involvement of the centrosome in the vital activity of endothelial cells, as well as its possible participation in the implementation of barrier function, the major function of endothelium.
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Affiliation(s)
- A S Shakhov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
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14-3-3γ Prevents Centrosome Amplification and Neoplastic Progression. Sci Rep 2016; 6:26580. [PMID: 27253419 PMCID: PMC4890593 DOI: 10.1038/srep26580] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 05/04/2016] [Indexed: 12/21/2022] Open
Abstract
More than 80% of malignant tumors show centrosome amplification and clustering. Centrosome amplification results from aberrations in the centrosome duplication cycle, which is strictly coordinated with DNA-replication-cycle. However, the relationship between cell-cycle regulators and centrosome duplicating factors is not well understood. This report demonstrates that 14-3-3γ localizes to the centrosome and 14-3-3γ loss leads to centrosome amplification. Loss of 14-3-3γ results in the phosphorylation of NPM1 at Thr-199, causing early centriole disjunction and centrosome hyper-duplication. The centrosome amplification led to aneuploidy and increased tumor formation in mice. Importantly, an increase in passage of the 14-3-3γ-knockdown cells led to an increase in the number of cells containing clustered centrosomes leading to the generation of pseudo-bipolar spindles. The increase in pseudo-bipolar spindles was reversed and an increase in the number of multi-polar spindles was observed upon expression of a constitutively active 14-3-3-binding-defective-mutant of cdc25C (S216A) in the 14-3-3γ knockdown cells. The increase in multi-polar spindle formation was associated with decreased cell viability and a decrease in tumor growth. Our findings uncover the molecular basis of regulation of centrosome duplication by 14-3-3γ and inhibition of tumor growth by premature activation of the mitotic program and the disruption of centrosome clustering.
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Chan N, Lim TM. Cytoplasmic nucleophosmin has elevated T199 phosphorylation upon which G2/M phase progression is dependent. Sci Rep 2015; 5:11777. [PMID: 26123729 PMCID: PMC4485321 DOI: 10.1038/srep11777] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2014] [Accepted: 05/26/2015] [Indexed: 01/28/2023] Open
Abstract
The cytoplasmic mutant of nucleophosmin (NPMc) is found approximately in one-third of acute myeloid leukemia (AML) cases and is highly associated with normal karyotype. Whereas previous studies have focused on wtNPM in centrosome duplication, we further elucidate the role of NPM in the cell cycle by utilizing the increased cytoplasmic load of NPMc. Overexpression of NPMc causes increased phosphorylation of NPM on T199 and, to a lesser degree, S4. T199 phosphorylation is dependent on cdk2 but activators of cdk2 were not elevated. Upon inhibition of cdk2, NPMc-overexpressing cells demonstrate a greater G2/M phase arrest than wtNPM or GFP counterparts. However, the number of cells with 2 centrosomes did not increase concordantly. This suggests that the arrest was caused by a delay in centrosome duplication, most likely due to the inhibition of centrosome duplication caused by unphosphorylated NPMc. Overall, these results suggest that the phosphorylation of T199 is important in the mitotic progression of NPMc-expressing cells. This further supports the hypothesis that NPMc is associated with normal karyotypes in AML because the higher cytoplasmic load of NPM can better suppress centrosome overduplication which would otherwise result in unequal segregation of chromosomes during mitosis, leading to aneuploidy and other genomic instabilities.
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Affiliation(s)
- Narisa Chan
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
| | - Tit Meng Lim
- Department of Biological Sciences, National University of Singapore, 14 Science Drive 4, Singapore 117543
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