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Spindle Assembly Checkpoint

Marie Duranteau, Jean-Jacques Montagne, Zohra Rahmani
The Spindle Assembly Checkpoint (SAC) is a surveillance mechanism that ensures accurate segregation of chromosomes into two daughter cells. BubR1, a key component of the SAC, play also a role in the mitotic timing since depletion of BubR1 leads to an accelerated mitosis. We previously found that, unlike what was reported in mammalian cells, mutation of the KEN1-box domain of Drosophila BubR1 (bubR1-KEN1 mutant) that affects the binding of BubR1 to Cdc20, the activating co-factor of the APC/C, did not accelerate the mitotic timing despite resulting in a defective SAC...
October 14, 2016: Biology Open
Grasiella Angelina Andriani, Vinnycius Pereira Almeida, Francesca Faggioli, Maurizio Mauro, Wanxia Li Tsai, Laura Santambrogio, Alexander Maslov, Massimo Gadina, Judith Campisi, Jan Vijg, Cristina Montagna
Age-related accumulation of ploidy changes is associated with decreased expression of genes controlling chromosome segregation and cohesin functions. To determine the consequences of whole chromosome instability (W-CIN) we down-regulated the spindle assembly checkpoint component BUB1 and the mitotic cohesin SMC1A, and used four-color-interphase-FISH coupled with BrdU incorporation and analyses of senescence features to reveal the fate of W-CIN cells. We observed significant correlations between levels of not-diploid cells and senescence-associated features (SAFs)...
October 12, 2016: Scientific Reports
Yoo Hong Min, Wootae Kim, Ja-Eun Kim
Mitotic progression is crucial for the maintenance of chromosomal stability. A proper progression is ensured by the activities of multiple kinases. One of these enzymes, the serine/threonine kinase Aurora A, is required for proper mitosis through the regulation of centrosome and spindle assembly. In this study, we functionally characterized a newly developed Aurora kinase A inhibitor, TC-A2317. In human lung cancer cells, TC-A2317 slowed proliferation by causing aberrant formation of centrosome and microtubule spindles and prolonging the duration of mitosis...
October 4, 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
Chuangyu Wen, Junxiong Chen, Di Zhang, Huihui Wang, Jia Che, Qiyuan Qin, Lu He, Zerong Cai, Mengmeng Lin, Qiong Lou, Lanlan Huang, Daici Chen, Aikichi Iwamoto, Donglin Ren, Lei Wang, Ping Lan, Jianping Wang, Huanliang Liu, Xiangling Yang
5-fluorouracil (5-FU)-based chemotherapy is the main chemotherapeutic approach for colorectal cancer (CRC) treatment. Because chemoresistance occurs frequently and significantly limits CRC therapies, a novel agent is needed. Pseudolaric acid B (PAB), a small molecule derived from the Chinese medicinal herb ''Tujinpi'', exhibits strong cytotoxic effects on a variety of cancers. However, the detailed mechanisms by which PAB inhibits CRC cell growth and its potential role in overcoming 5-FU resistance have not been well studied...
October 3, 2016: Cancer Letters
Boris Topolski, Visnja Jakopec, Natascha A Künzel, Ursula Fleig
Chromosome transmission fidelity during mitosis is of critical importance for the fitness of an organism as mistakes will lead to aneuploidy, which has a causative role in numerous severe diseases. Proper segregation of chromosomes depends on interdependent processes at the microtubule-kinetochore interface and the spindle assembly checkpoint. Here we report the discovery of a new element essential for chromosome transmission fidelity that implicates inositol pyrophosphates (IPPs) as playing a key role in this process...
October 3, 2016: Molecular and Cellular Biology
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...
October 1, 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
Irina Alimova, June Ng, Peter Harris, Diane Birks, Andrew Donson, Michael D Taylor, Nicholas K Foreman, Sujatha Venkataraman, Rajeev Vibhakar
Medulloblastoma is the most common type of malignant brain tumor that affects children. Although recent advances in chemotherapy and radiation have improved outcomes, high-risk patients perform poorly with significant morbidity. Gene expression profiling has revealed that monopolar spindle 1 (MPS1) (TTK1) is highly expressed in medulloblastoma patient samples compared to that noted in normal cerebellum. MPS1 is a key regulator of the spindle assembly checkpoint (SAC), a mitotic mechanism specifically required for proper chromosomal alignment and segregation...
September 12, 2016: Oncology Reports
M Kasim Diril, Xavier Bisteau, Mayumi Kitagawa, Matias J Caldez, Sheena Wee, Jayantha Gunaratne, Sang Hyun Lee, Philipp Kaldis
The Greatwall kinase/Mastl is an essential gene that indirectly inhibits the phosphatase activity toward mitotic Cdk1 substrates. Here we show that although Mastl knockout (MastlNULL) MEFs enter mitosis, they progress through mitosis without completing cytokinesis despite the presence of misaligned chromosomes, which causes chromosome segregation defects. Furthermore, we uncover the requirement of Mastl for robust spindle assembly checkpoint (SAC) maintenance since the duration of mitotic arrest caused by microtubule poisons in MastlNULL MEFs is shortened, which correlates with premature disappearance of the essential SAC protein Mad1 at the kinetochores...
September 2016: PLoS Genetics
Xiuliang Cui, Xiaofeng Li, Jin Li, Xue Wang, Wen Sun, Zhuo Cheng, Jin Ding, Hongyang Wang
Capturing the predominant driver genes is critical in the analysis of high-throughput experimental data; however, existing methods scarcely include the unique characters of biological networks. Herein we introduced a ranking-based computational framework (inFRank) to rank the proteins by their influence. Using inFRank, we identified the top 20 influential genes in hepatocellular carcinoma (HCC). Network analysis revealed a prominent community composed of 7 influential genes. Intriguingly, five genes among the community were critical for mitotic spindle assembly checkpoint (SAC), suggesting that dysregulation of SAC could be a distinct feature of HCC and targeting SAC-associated genes might be a promising therapeutic strategy...
September 7, 2016: Oncotarget
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
David M Higgins, Natalie J Nannas, R Kelly Dawe
The classic maize mutant divergent spindle-1 (dv1) causes failures in meiotic spindle assembly and a decrease in pollen viability. By analyzing two independent dv1 alleles we demonstrate that this phenotype is caused by mutations in a member of the kinesin-14A subfamily, a class of C-terminal, minus-end directed microtubule motors. Further analysis demonstrates that defects in early spindle assembly are rare, but that later stages of spindle organization promoting the formation of finely focused spindle poles are strongly dependent on Dv1...
2016: Frontiers in Plant Science
Jing Chen, Jian Liu
Chromosome segregation during mitosis hinges on proper assembly of the microtubule spindle that establishes bipolar attachment to each chromosome. Experiments demonstrate allometry of mitotic spindles and a universal scaling relationship between spindle size and cell size across metazoans, which indicates a conserved principle of spindle assembly at play during evolution. However, the nature of this principle is currently unknown. Researchers have focused on deriving the mechanistic underpinning of the size scaling from the mechanical aspects of the spindle assembly process...
September 6, 2016: Biophysical Journal
Xihan Guo, Xu Wang
The fruit of Phyllanthus emblica Linn. (PE) has been widely consumed as a functional food and folk medicine in Southeast Asia due to its remarkable nutritional and pharmacological effects. Previous research showed PE delays mitotic progress and increases genomic instability (GIN) in human colorectal cancer cells. This study aimed to investigate the similar effects of PE by the biomarkers related to spindle assembly checkpoint (SAC), mitotic aberrations and GIN in human NCM460 normal colon epithelial cells. Cells were treated with PE and harvested differently according to the biomarkers observed...
2016: International Journal of Molecular Sciences
Chris A Smith, Andrew D McAinsh, Nigel J Burroughs
Chromosome segregation is a mechanical process that requires assembly of the mitotic spindle - a dynamic microtubule-based force-generating machine. Connections to this spindle are mediated by sister kinetochore pairs, that form dynamic end-on attachments to microtubules emanating from opposite spindle poles. This bi-orientation generates forces that have been reported to stretch the kinetochore itself, which has been suggested to stabilise attachment and silence the spindle checkpoint. We reveal using three dimensional tracking that the outer kinetochore domain can swivel around the inner kinetochore/centromere, which results in large reductions in intra-kinetochore distance (delta) when viewed in lower dimensions...
September 3, 2016: ELife
Dimitriya H Garvanska, Marie Sofie Yoo Larsen, Jakob Nilsson
The spindle assembly checkpoint (SAC) inhibits the anaphase-promoting complex/cyclosome (APC/C) in response to unattached kinetochores by generating a diffusible inhibitor termed the mitotic checkpoint complex (MCC). At metaphase, rapid activation of the APC/C requires removal of the MCC, a process that has been shown to depend on the APC/C E2 enzymes, UBE2C and UBE2S. Here we investigate the in vivo role of the APC/C E2 enzymes in SAC silencing using CRISPR/Cas9 genetically engineered HCT116 UBE2C or UBE2S null cell lines...
October 15, 2016: Biology Open
Lan Yu, Zeng-Fu Shang, Salim Abdisalaam, Kyung-Jong Lee, Arun Gupta, Jer-Tsong Hsieh, Aroumougame Asaithamby, Benjamin P C Chen, Debabrata Saha
Defects in kinetochore-microtubule (KT-MT) attachment and the spindle assembly checkpoint (SAC) during cell division are strongly associated with chromosomal instability (CIN). CIN has been linked to carcinogenesis, metastasis, poor prognosis and resistance to cancer therapy. We previously reported that the DAB2IP is a tumor suppressor, and that loss of DAB2IP is often detected in advanced prostate cancer (PCa) and is indicative of poor prognosis. Here, we report that the loss of DAB2IP results in impaired KT-MT attachment, compromised SAC and aberrant chromosomal segregation...
October 14, 2016: Nucleic Acids Research
Ayae Ikawa-Yoshida, Takuya Matsumoto, Shinji Okano, Yukihiko Aoyagi, Yutaka Matsubara, Tadashi Furuyama, Yoshimichi Nakatsu, Teruhisa Tsuzuki, Mitsuho Onimaru, Tomoko Ohkusa, Masatoshi Nomura, Yoshihiko Maehara
A delay in liver regeneration after partial hepatectomy (PHx) leads to acute liver injury, and such delays are frequently observed in aged patients. BubR1 (budding uninhibited by benzimidazole-related 1) controls chromosome mitotic segregation through the spindle assembly checkpoint, and BubR1 down-regulation promotes aging-associated phenotypes. In this study we investigated the effects of BubR1 insufficiency on liver regeneration in mice. Low-BubR1-expressing mutant (BubR1(L/L)) mice had a delayed recovery of the liver weight-to-body weight ratio and increased liver deviation enzyme levels after PHx...
2016: Scientific Reports
Raphael Berges, Aurélie Tchoghandjian, Stephane Honore, Marie-Anne Esteve, Dominique Figarella-Branger, Felix Bachmann, Heidi A Lane, Diane Braguer
Glioblastoma (GBM) patients have limited treatment options. Cancer stem-like cells (CSLCs) contribute to GBM invasiveness and repopulation; hence, they represent promising targets for novel therapies. BAL101553 is a prodrug of BAL27862, a novel microtubule-destabilizing agent inhibiting tumor cell proliferation through activation of the Spindle Assembly Checkpoint, which is currently in Phase 1/2 clinical development. Broad anti-cancer activity has been demonstrated against human cancer models, including tumors refractory to conventional treatments...
August 18, 2016: Molecular Cancer Therapeutics
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