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Zhejian Ji, Haishan Gao, Luying Jia, Bing Li, Hongtao Yu
The master spindle checkpoint kinase Mps1 directly senses kinetochore-microtubule attachment and promotes checkpoint signaling to ensure accurate chromosome segregation. The kinetochore scaffold Knl1, when phosphorylated by Mps1, recruits checkpoint complexes Bub1-Bub3 and BubR1-Bub3 to unattached kinetochores. Active checkpoint signaling ultimately enhances the assembly of the mitotic checkpoint complex (MCC) consisting of BubR1-Bub3, Mad2, and Cdc20, which inhibits the anaphase-promoting complex or cyclosome bound to Cdc20 (APC/C(Cdc20)) to delay anaphase onset...
January 10, 2017: ELife
Ivan Yuan, Ioanna Leontiou, Priya Amin, Karen M May, Sadhbh Soper Ní Chafraidh, Eliška Zlámalová, Kevin G Hardwick
The spindle checkpoint acts as a mitotic surveillance system, monitoring interactions between kinetochores and spindle microtubules and ensuring high-fidelity chromosome segregation [1-3]. The checkpoint is activated by unattached kinetochores, and Mps1 kinase phosphorylates KNL1 on conserved MELT motifs to generate a binding site for the Bub3-Bub1 complex [4-7]. This leads to dynamic kinetochore recruitment of Mad proteins [8, 9], a conformational change in Mad2 [10-12], and formation of the mitotic checkpoint complex (MCC: Cdc20-Mad3-Mad2 [13-15])...
January 9, 2017: Current Biology: CB
Yuan-Xiang Shi, Tao Zhu, Ting Zou, Wei Zhuo, Yi-Xin Chen, Ma-Sha Huang, Wei Zheng, Chen-Jing Wang, Xi Li, Xiao-Yuan Mao, Wei Zhang, Hong-Hao Zhou, Ji-Ye Yin, Zhao-Qian Liu
Lung cancer remains as the leading cause of cancer-related death worldwide, and lung adenocarcinoma (LUAD) is the most common histological subtype. This study aims to investigate biomarkers associated with cancer progression and prognosis of LUAD. We integrated expression profiles of 668 lung cancer patients in five datasets from the Gene Expression Omnibus (GEO) and identified a panel of differentially expressed genes (DEGs). Function enrichment analysis highlighted that these genes were closely associated with the carcinogenesis of LUAD, such as cell cycle, ECM-receptor interaction and p53 signaling pathway...
November 9, 2016: Oncotarget
Teng Zhang, Yang Zhou, Hong-Hui Wang, Tie-Gang Meng, Lei Guo, Xue-Shan Ma, Wei Shen, Heide Schatten, Qing-Yuan Sun
Mammalian oocytes are particularly error prone in chromosome segregation during two successive meiotic divisions. The proper kinetochore-microtubule attachment is a prerequisite for faithful chromosome segregation during meiosis. Here, we report that Spc24 localizes at the kinetochores during mouse oocyte meiosis. Depletion of Spc24 using specific siRNA injection caused defective kinetochore-microtubule attachments and chromosome misalignment, and accelerated the first meiosis by abrogating the kinetochore recruitment of spindle assembly checkpoint protein Mad2, leading to a high incidence of aneuploidy...
October 4, 2016: Oncotarget
Ana Vanessa Nascimento, Amit Singh, Hassan Bousbaa, Domingos Ferreira, Bruno Sarmento, Mansoor M Amiji
: Efficiency of chemotherapy is often limited by low therapeutic index of the drug as well as emergence of inherent and acquired drug resistance in cancer cells. As a common strategy to overcome drug resistance, higher doses of chemo-agents are administered. However, adverse side effects are usually increased as a consequence. A potentially effective approach is to combine chemotherapy with other therapeutic strategies such as small interfering RNAs (siRNAs) that allow the use of lower yet efficient doses of the anticancer drugs...
January 1, 2017: Acta Biomaterialia
HaiYang Wang, Yu-Jin Jo, Tian-Yi Sun, Suk Namgoong, Xiang-Shun Cui, Jeong Su Oh, Nam-Hyung Kim
To ensure accurate chromosome segregation, the spindle assembly checkpoint (SAC) delays anaphase onset by preventing the premature activation of anaphase-promoting complex/cyclosome (APC/C) until all kinetochores are attached to the spindle. Although an escape from mitosis in the presence of unsatisfied SAC has been shown in several cancer cells, it has not been reported in oocyte meiosis. Here, we show that CDK7 activity is required to prevent a bypass of SAC during meiosis I in mouse oocytes. Inhibition of CDK7 using THZ1 accelerated the first meiosis, leading to chromosome misalignment, lag of chromosomes during chromosome segregation, and a high incidence of aneuploidy...
December 2016: Biochimica et Biophysica Acta
Gaurav Kumar Singh, Sharanbasappa Shrimant Karade, Rajeev Ranjan, Nafees Ahamad, Shakil Ahmed
The mitotic arrest deficiency 2 (Mad2) protein is an essential component of the spindle assembly checkpoint that interacts with Cdc20/Slp1 and inhibit its ability to activate anaphase promoting complex/cyclosome (APC/C). In bladder cancer cell line the C-terminal residue of the mad2 gene has been found to be deleted. In this study we tried to understand the role of the C-terminal region of mad2 on the spindle checkpoint function. To envisage the role of C-terminal region of Mad2, we truncated 25 residues of Mad2 C-terminal region in fission yeast S...
September 23, 2016: Molecular Biology Reports
Maria Del Mar Mora-Santos, America Hervas-Aguilar, Katharina Sewart, Theresa C Lancaster, John C Meadows, Jonathan B A Millar
The spindle assembly checkpoint (SAC) ensures that sister chromatids do not separate until all chromosomes are attached to spindle microtubules and bi-oriented. Spindle checkpoint proteins, including Mad1, Mad2, Mad3 (BubR1), Bub1, Bub3, and Mph1 (Mps1), are recruited to unattached and/or tensionless kinetochores. SAC activation catalyzes the conversion of soluble Mad2 (O-Mad2) into a form (C-Mad2) that binds Cdc20, BubR1, and Bub3 to form the mitotic checkpoint complex (MCC), a potent inhibitor of the anaphase-promoting complex (APC/C)...
October 10, 2016: Current Biology: CB
Jianhui Ji, Ding Tang, Yi Shen, Zhihui Xue, Hongjun Wang, Wenqing Shi, Chao Zhang, Guijie Du, Yafei Li, Zhukuan Cheng
The human mitotic arrest-deficient 2 (Mad2) binding protein p31(comet) participates in the spindle checkpoint and coordinates cell cycle events in mitosis although its function in meiosis remains unknown in all organisms. Here, we reveal P31(comet) as a synaptonemal complex (SC) protein in rice (Oryza sativa L.). In p31(comet), homologous pairing and synapsis are eliminated, leading to the homologous nondisjunction and complete sterility. The failure in loading of histone H2AX phosphorylation (γH2AX) in p31(comet), together with the suppressed chromosome fragmentation in rice completion of meiotic recombination 1 (com1) p31(comet) and radiation sensitive 51c (rad51c) p31(comet) double mutants, indicates that P31(comet) plays an essential role in double-strand break (DSB) formation...
September 20, 2016: Proceedings of the National Academy of Sciences of the United States of America
Kristyna Markova, Magdalena Uzlikova, Pavla Tumova, Klara Jirakova, Guy Hagen, Jaroslav Kulda, Eva Nohynkova
The spindle assembly checkpoint (SAC) joins the machinery of chromosome-to-spindle microtubule attachment with that of the cell cycle to prevent missegregation of chromosomes during mitosis. Although a functioning SAC has been verified in a limited number of organisms, it is regarded as an evolutionarily conserved safeguard mechanism. In this report, we focus on the existence of the SAC in a single-celled parasitic eukaryote, Giardia intestinalis. Giardia belongs to Excavata, a large and diverse supergroup of unicellular eukaryotes in which SAC control has been nearly unexplored...
October 2016: European Journal of Cell Biology
Yi-Feng Yuan, Yi-Xin Ren, Peng Yuan, Li-Ying Yan, Jie Qiao
Recent whole-exome sequencing (WES) studies demonstrated that TRAIP is associated with primordial dwarfism. Although TRAIP was partially studied in mitosis, its function in oocyte meiosis remained unknown. In this study, we investigated the roles of TRAIP during mouse oocyte meiosis. TRAIP was stably expressed during oocytes meiosis and co-localized with CREST at the centromere region. Knockdown of TRAIP led to DNA damage, as revealed by the appearance of γH2AX. Although oocytes meiotic maturation was not affected, the proportions of misaligned chromosomes and aneuploidy were elevated after TRAIP knockdown, suggesting TRAIP is required for stable kinetochore-microtubule (K-MT) attachment...
2016: Scientific Reports
Eunhee Choi, Xiangli Zhang, Chao Xing, Hongtao Yu
Insulin signaling regulates many facets of animal physiology. Its dysregulation causes diabetes and other metabolic disorders. The spindle checkpoint proteins MAD2 and BUBR1 prevent precocious chromosome segregation and suppress aneuploidy. The MAD2 inhibitory protein p31(comet) promotes checkpoint inactivation and timely chromosome segregation. Here, we show that whole-body p31(comet) knockout mice die soon after birth and have reduced hepatic glycogen. Liver-specific ablation of p31(comet) causes insulin resistance, hyperinsulinemia, glucose intolerance, and hyperglycemia and diminishes the plasma membrane localization of the insulin receptor (IR) in hepatocytes...
July 28, 2016: Cell
Xuan Li, Yan-Kui Wang, Zhi-Qiang Song, Zhi-Qiang Du, Cai-Xia Yang
Meiotic maturation of mammalian oocytes is a precisely orchestrated and complex process. Dimethyl sulfoxide (DMSO), a widely used solvent, drug, and cryoprotectant, is capable of disturbing asymmetric cytokinesis of oocyte meiosis in mice. However, in pigs, DMSO's effect on oocyte meiosis still remains unknown. We aimed to evaluate if DMSO treatment will affect porcine oocyte meiosis and the underlying molecular changes as well. Interestingly, we did not observe the formation of the large first polar body and symmetric division for porcine oocytes treated with DMSO, contrary to findings reported in mice...
2016: PloS One
Jayasha Shandilya, Kathryn F Medler, Stefan G E Roberts
Cell cycle checkpoint signaling stringently regulates chromosome segregation during cell division. MAD2 is one of the key components of the spindle and mitotic checkpoint complex that regulates the fidelity of cell division along with MAD1, CDC20, BUBR1, BUB3 and MAD3. MAD2 ablation leads to erroneous attachment of kinetochore-spindle fibers and defective chromosome separation. A potential role for MAD2 in the regulation of events beyond the spindle and mitotic checkpoints is not clear. Together with active spindle assembly checkpoint signaling, AURORA B kinase activity is essential for chromosome condensation as cells enter mitosis...
August 17, 2016: Cell Cycle
Alejandro López-Saavedra, Miguel Ramírez-Otero, José Díaz-Chávez, Rodrigo Cáceres-Gutiérrez, Monserrat Justo-Garrido, Marco A Andonegui, Julia Mendoza, Ángela Downie-Ruíz, Carlo Cortés-González, Nancy Reynoso, Clementina Castro-Hernández, Guadalupe Domínguez-Gómez, Miguel Santibáñez, Eunice Fabián-Morales, Franz Pruefer, Fernando Luna-Maldonado, Rodrigo González-Barrios, Luis A Herrera
BACKGROUND: Prolonged mitotic arrest in response to anti-cancer chemotherapeutics, such as DNA-damaging agents, induces apoptosis, mitotic catastrophe, and senescence. Disruptions in mitotic checkpoints contribute resistance to DNA-damaging agents in cancer. MAD2 has been associated with checkpoint failure and chemotherapy response. In this study, a novel splice variant of MAD2, designated MAD2γ, was identified, and its association with the DNA damage response was investigated. METHODS: Endogenous expression of MAD2γ and full-length MAD2 (MAD2α) was measured using RT-PCR in cancer cell lines, normal foreskin fibroblasts, and tumor samples collected from patients with testicular germ cell tumors (TGCTs)...
August 2, 2016: Cell Cycle
Konstantina Rowald, Martina Mantovan, Joana Passos, Christopher Buccitelli, Balca R Mardin, Jan O Korbel, Martin Jechlinger, Rocio Sotillo
Chromosome instability (CIN) is associated with poor survival and therapeutic outcome in a number of malignancies. Despite this correlation, CIN can also lead to growth disadvantages. Here, we show that simultaneous overexpression of the mitotic checkpoint protein Mad2 with Kras(G12D) or Her2 in mammary glands of adult mice results in mitotic checkpoint overactivation and a delay in tumor onset. Time-lapse imaging of organotypic cultures and pathologic analysis prior to tumor establishment reveals error-prone mitosis, mitotic arrest, and cell death...
June 21, 2016: Cell Reports
Guðjón Ólafsson, Peter H Thorpe
The spindle assembly checkpoint (SAC) is a key mechanism to regulate the timing of mitosis and ensure that chromosomes are correctly segregated to daughter cells. The recruitment of the Mad1 and Mad2 proteins to the kinetochore is normally necessary for SAC activation. This recruitment is coordinated by the SAC kinase Mps1, which phosphorylates residues at the kinetochore to facilitate binding of Bub1, Bub3, Mad1, and Mad2. There is evidence that the essential function of Mps1 is to direct recruitment of Mad1/2...
2016: G3: Genes—Genomes—Genetics
Andria Schibler, Evangelia Koutelou, Junya Tomida, Marenda Wilson-Pham, Li Wang, Yue Lu, Alexa Parra Cabrera, Renee J Chosed, Wenqian Li, Bing Li, Xiaobing Shi, Richard D Wood, Sharon Y R Dent
Histone H3 methylation on Lys4 (H3K4me) is associated with active gene transcription in all eukaryotes. In Saccharomyces cerevisiae, Set1 is the sole lysine methyltransferase required for mono-, di-, and trimethylation of this site. Although H3K4me3 is linked to gene expression, whether H3K4 methylation regulates other cellular processes, such as mitosis, is less clear. Here we show that both Set1 and H3K4 mutants display a benomyl resistance phenotype that requires components of the spindle assembly checkpoint (SAC), including Bub3 and Mad2...
May 15, 2016: Genes & Development
Pavithra Aravamudhan, Renjie Chen, Babhrubahan Roy, Janice Sim, Ajit P Joglekar
Recruitment of spindle assembly checkpoint (SAC) proteins by an unattached kinetochore leads to SAC activation. This recruitment is licensed by the Mps1 kinase, which phosphorylates the kinetochore protein Spc105 at one or more of its six MELT repeats. Spc105 then recruits the Bub3-Bub1 and Mad1-Mad2 complexes, which produce the inhibitory signal that arrests cell division. The strength of this signal depends, in part, on the number of Bub3-Bub1 and Mad1-Mad2 molecules that Spc105 recruits. Therefore regulation of this recruitment will influence SAC signaling...
November 7, 2016: Molecular Biology of the Cell
Benjamin M Stormo, Donald T Fox
Duplicating chromosomes once each cell cycle produces sister chromatid pairs, which separate accurately at anaphase. In contrast, reduplicating chromosomes without separation frequently produces polytene chromosomes, a barrier to accurate mitosis. Chromosome reduplication occurs in many contexts, including: polytene tissue development, polytene tumors, and following treatment with mitosis-blocking chemotherapeutics. However, mechanisms responding to or resolving polyteny during mitosis are poorly understood...
2016: ELife
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