Adapter protein able to interact with different proteins and involved in different biological processes. Mediates the interaction between the error-prone DNA polymerase zeta catalytic subunit REV3L and the inserter polymerase REV1, thereby mediating the second polymerase switching in translesion DNA synthesis. Translesion DNA synthesis releases the replication blockade of replicative polymerases, stalled in presence of DNA lesions. May also regulate another aspect of cellular response to DNA damage through regulation of the JNK-mediated phosphorylation and activation of the transcriptional activator ELK1. Inhibits the FZR1- and probably CDC20-mediated activation of the anaphase promoting complex APC thereby regulating progression through the cell cycle. Regulates TCF7L2-mediated gene transcription and may play a role in epithelial-mesenchymal transdifferentiation.

PubMed comprises more than 30 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

Detailed annotation info for ENST00000235310; Mitotic spindle assembly checkpoint protein MAD2B (MAD2-like 2) (hREV7). [Source:Uniprot/SWISSPROT;Acc:Q9UI95 ...

KT localization analysis of an extensive hSpindly mutant library consisting of truncation, insertion, deletion, and substitution constructs showed that both the coiled-coil domain II and the C terminus of hSpindly are required for KT localization (Figs. 1 and 2). Although Barisic et al. (2010) has previously shown that the 293-605-aa fragment of hSpindly did not localize to KTs, we found that this specific deletion (N3 construct) does not impair KT localization of hSpindly (Fig. 1). This discrepancy could be the result of overexpression, differences in fusion tags, or the sensitivity of the two assays. Overexpression of coiled-coil proteins often results in aggregation, which can lead to mislocalization of the protein, resulting in a false negative. Immunostaining with anti-FLAG antibody to analyze KT localization by Barisic et al. (2010) compared with GFP fusion constructs may influence the detection sensitivity and our assay is maximized for sensitivity with vinblastine treatment. Barisic et ...

The mitotic checkpoint protein Bub3 is involved with the essential spindle checkpoint pathway which operates during early embryogenesis. Bub3 is…

This sequence change results in a premature translational stop signal in the SACS gene (p.Leu3192Phefs*4). While this is not anticipated to result in nonsense mediated decay, it is expected to disrupt the last 1,388 amino acids of the SACS protein. This variant is not present in population databases (ExAC no frequency). This variant has not been reported in the literature in individuals with SACS-related conditions. This variant disrupts the C-terminus of the SACS protein. Other variant(s) that disrupt this region (p.Gln4054*) have been determined to be pathogenic (PMID: 18465152, 27288452, Invitae). This suggests that variants that disrupt this region of the protein are likely to be causative of disease. For these reasons, this variant has been classified as Pathogenic ...

We show here that CIN colon cancer cells undergo transient mitotic arrest in response to spindle damage. However, the maximum mitotic indices achieved by the CIN cells is lower than that of the MIN cells. Thus, we argue that the aneuploid colon cancer cells examined here have a robust spindle checkpoint. Consistently, it now appears that mutations in known spindle checkpoint genes are extremely rare in human tumours (Cahill et al., 1998, 1999a; Imai et al., 1999; Yamaguchi et al., 1999; Myrie et al., 2000; Sato et al., 2000). The reason for the apparent lack of such mutations may be that they are lethal. Although spindle checkpoint genes are non‐essential in yeast (reviewed in Taylor, 1999) mutations in MAD2 and BUB3 result in embryonic lethality in mice (Dobles et al., 2000; Kalitsis et al., 2000). Furthermore, disrupting Bub1 and Mad2 function accelerates mitotic exit in human cells suggesting that spindle checkpoint function may be required to complete normal somatic cell divisions (Taylor ...

p,The AAA+ family ATPase TRIP13 is a key regulator of meiotic recombination and the spindle assembly checkpoint, acting on signaling proteins of the conserved HORMA domain family. Here we present the structure of the Caenorhabditis elegans TRIP13 ortholog PCH-2, revealing a new family of AAA+ ATPase protein remodelers. PCH-2 possesses a substrate-recognition domain related to those of the protein remodelers NSF and p97, while its overall hexameric architecture and likely structural mechanism bear close similarities to the bacterial protein unfoldase ClpX. We find that TRIP13, aided by the adapter protein p31(comet), converts the HORMA-family spindle checkpoint protein MAD2 from a signaling-active closed conformer to an inactive open conformer. We propose that TRIP13 and p31(comet) collaborate to inactivate the spindle assembly checkpoint through MAD2 conformational conversion and disassembly of mitotic checkpoint complexes. A parallel HORMA protein disassembly activity likely underlies ...

Mouse models of CIN. The most extensive evaluation of the role of aneuploidy in tumour formation stems from the analysis of mouse models with conditional or hypomorphic mutations in mitotic checkpoint genes [[10],[12],[14],[111],[112],[133],[134],[135],[136]]. Complete inactivation of the checkpoint early in embryogenesis leads to embryonic lethality, underscoring the essential role of the checkpoint in organism development. However, genetically engineered mice with an attenuated mitotic checkpoint are viable and display CIN and increased levels of aneuploidy in cells and tissues [[10],[12],[14],[111],[112],[133],[136],[137],[138],[139]]. Notably, as these animal models induce aneuploidy through continued CIN, the effect of aneuploidy in tumour development independently of CIN cannot be assessed. Several of these mice have increased spontaneous tumorigenesis, strongly supporting that CIN increases the probability of tumour formation ([[10],[110],[133],[139]]; for extensive reviews of the types ...

S. Mosalaganti, J. Keller, A. Altenfeld, M. Winzker, P. Rombaut, M. Saur, A. Petrovic, A. Wehenkel, S. Wohlgemuth, F. Müller, S. Maffini, T. Bange, F. Herzog, H. Waldmann, S. Raunser, A. Musacchio: Structure of the RZZ complex and molecular basis of its interaction with Spindly. J Cell Biol. 2017, 216:961-981.. A. C. Faesen, M. Thanasoula, S. Maffini, C. Breit, F. Müller, S. van Gerwen, T. Bange, A. Musacchio: Basis of catalytic assembly of the mitotic checkpoint complex. Nature. 2017, 542:498-502.. D. Pan, K. Klare, A. Petrovic, A. Take, K. Walstein, P. Singh, A. Rondelet, A.W. Bird, A. Musacchio: CDK-regulated dimerization of M18BP1 on a Mis18 hexamer is necessary for CENP-A loading. Elife. 2017 6. pii: e23352.. A. Petrovic, J. Keller, Y. Liu, K. Overlack, J. John, Y. Dimitrova, S. Jenni, S. van Gerwen, P. Stege, S. Wohlgemuth, P. Rombaut, F. Herzog, S.C. Harrison, I. Vetter, A. Musacchio: Structure of the MIS12 complex and molecular basis of its interaction with CENP-C at human ...

New therapies, designed to enhance anti-tumor immunity are based on the blockade of the checkpoint components, either PD-1 on immune cells or PD-L1 on tumor cells. This strategy, while being spectacularly successful in some patients for some cancers, fails for many other patients. The expression of PD-L1 is highly dynamic and its prevalence within tumors can vary significantly over time. The curre .... ...

In eukaryotic cells, accurate chromosome segregation requires the spindle assembly checkpoint, a surveillance system monitoring kinetochore attachment to microtubules of the mitotic spindle (Lara-Gonzalez et al., 2012; Musacchio, 2015). The spindle checkpoint kinase MPS1 binds to unattached kinetochores and phosphorylates kinetochore proteins, thus directing the accumulation of spindle checkpoint proteins of the MAD and BUB families (Musacchio, 2015; Ciliberto and Hauf, 2017). A subset of the MAD and BUB proteins then assemble into the mitotic checkpoint complex (MCC; Musacchio, 2015). The mitotic checkpoint complex then diffuses away from the kinetochore to inhibit the ubiquitin E3 ligase anaphase promoting complex/cyclosome (APC/C), thus preventing mitotic exit (Sivakumar and Gorbsky, 2015). The two crucial targets ubiquitylated by the APC/C to promote mitotic exit are securin, the inhibitor of separase, and most important for this work, cyclin B, the activating subunit of a cyclin-dependent ...

Thank you for your interest in spreading the word on PNAS.. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.. ...

centrosome, condensed chromosome kinetochore, condensed nuclear chromosome kinetochore, cytoplasm, kinetochore, nucleoplasm, pronucleus, spindle midzone, embryo development ending in birth or egg hatching, mitotic spindle assembly checkpoint

To delete SGO1, primers O361 and O362 were used to PCR amplify the Kluyveromyces lactis TRP1 selective marker from plasmid pBS1479 (47), and the PCR product was transformed into yeast cells for tryptophan prototroph selection.. To tag endogenous Pds1p with 13×Myc, O323 and O324 were used to PCR amplify pFA6a-13Myc-TRP1 for yeast integrative transformation. Integration was verified with PDS1-specific primers O325 and O326 and TRP1-specific primers O375 and O376. Mcd1p-13Myc was created in a scheme identical to that used for Pds1p-13Myc, except for the use of MCD1-specific primers OJL21, OJL22 (for integration), and OJL23 (for verification). To introduce a carboxyl-terminal six-hemagglutinin (6×HA) tag into Sgo1p, yeast strain A10652 (22) was used for a genomic PCR (primers O363 and O364) that amplified the 6×HA-TRP1 fragment flanked by SGO1 sequences. The resultant PCR product was transformed into yMK1243 and yJL145 to knock in the HA tag and the TRP1 marker, creating yJL343 and yJL344, ...

InterPro provides functional analysis of proteins by classifying them into families and predicting domains and important sites. We combine protein signatures from a number of member databases into a single searchable resource, capitalising on their individual strengths to produce a powerful integrated database and diagnostic tool.

4H7X: Structural and functional insights into the role of the N-terminal Mps1 TPR domain in the SAC (spindle assembly checkpoint).

TY - JOUR. T1 - Histone H3K4 methylation regulates deactivation of the spindle assembly checkpoint through direct binding of Mad2. AU - Schibler, Andria. AU - Koutelou, Evangelia. AU - Tomida, Junya. AU - Wilson-Pham, Marenda. AU - Wang, Li. AU - Lu, Yue. AU - Cabrera, Alexa Parra. AU - Chosed, Renee J.. AU - Li, Wenqian. AU - Li, Bing. AU - Shi, Xiaobing. AU - Wood, Richard D.. AU - Dent, Sharon Y R. PY - 2016/5/15. Y1 - 2016/5/15. N2 - 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. These proteins ...

Fidelity of chromosome segregation is monitored by the spindle assembly checkpoint (SAC). Key components of the SAC include MAD1, MAD2, BUB1, BUB3, BUBR1, and MPS1. These proteins accumulate on...

Weaver and Cleveland and Taylor et al. contend that our data on the involvement of the γ-tubulin ring complex (γ-TuRC) in the spindle assembly checkpoint (SAC) can be fully explained by kinetochore-derived checkpoint signaling. We maintain that (i) the interactions of γ-TuRC with Cdc20 and BubR1, and (ii) the activation of SAC by γ-TuRC depletion, in addition to the abrogation of kinetochore-microtubule interactions, argue for a more complex mechanism of SAC signaling.. ...

A previous report has shown that microtubule depolymerization by nocodazole treatment arrests cell cycle extracts in M phase if containing very high densities of sperm nuclei. The use of MKP-1 further suggested that MAP kinase, the most likely target of MKP-1, may have a role in the spindle assembly checkpoint (20). However, whether classical MAP kinase is involved in the mitotic arrest remains to be determined. To address this question, we used MAP kinase-depleted extracts. We monitored the level of MPF as histone H1 kinase activity in the extracts supplemented with 9,000 sperm nuclei/μl. In the absence of nocodazole, the extracts returned to interphase after the first M phase, irrespective of whether MAP kinase was depleted or not (Fig. 3,A). In the presence of nocodazole, mock-treated extracts were arrested at the first M phase and the high MPF activity was sustained (Fig. 3,B, mock), whereas MAP kinase-depleted extracts returned to interphase after the first M phase (Fig. 3,B, αMAPK). In ...

Microtubules are dynamic polymers that play crucial roles in a large number of cellular functions. Their pivotal role in mitosis makes them a target for the development of anticancer drugs. Microtubule-damaging agents suppress microtubule dynamics, leading to disruption of the mitotic spindle in dividing cells, cell cycle arrest at M phase, and late apoptosis. A better understanding of the processes coupling microtubule damage to the onset of apoptosis will reveal sites of potential intervention in cancer chemotherapy. Inhibition of microtubule dynamics induces persistent modification of biological processes (M arrest) and signaling pathways (mitotic spindle assembly checkpoint activation, Bcl-2 phosphorylation, c-Jun NH2-terminal kinase activation), which ultimately lead to apoptosis through the accumulation of signals that finally reach the threshold for the onset of apoptosis or through diminishing the threshold for engagement of cell death. Microtubules serve also as scaffolds for signaling ...

Microtubules are dynamic polymers that play crucial roles in a large number of cellular functions. Their pivotal role in mitosis makes them a target for the development of anticancer drugs. Microtubule-damaging agents suppress microtubule dynamics, leading to disruption of the mitotic spindle in dividing cells, cell cycle arrest at M phase, and late apoptosis. A better understanding of the processes coupling microtubule damage to the onset of apoptosis will reveal sites of potential intervention in cancer chemotherapy. Inhibition of microtubule dynamics induces persistent modification of biological processes (M arrest) and signaling pathways (mitotic spindle assembly checkpoint activation, Bcl-2 phosphorylation, c-Jun NH2-terminal kinase activation), which ultimately lead to apoptosis through the accumulation of signals that finally reach the threshold for the onset of apoptosis or through diminishing the threshold for engagement of cell death. Microtubules serve also as scaffolds for signaling ...

The Ran GTPase controls many cellular functions, including nucleocytoplasmic trafficking, spindle assembly, nuclear assembly and cell-cycle progression. Considerable evidence suggests that diffusible Ran-GTP near mitotic chromatin facilitates the release of critical factors from nuclear transport receptors, thereby promoting organization of mitotic spindles with respect to chromosomes. In addition to this role of soluble Ran-GTP, Ran has two important but less understood roles at mitotic kinetochores. Namely, it is essential for regulation of the spindle assembly checkpoint and for assembly of microtubule fibres that attach kinetochores to spindle poles. Here, I will briefly summarize evidence for these kinetochore-associated functions and mention some of the issues that remain to be addressed regarding them. ...

BACKGROUND Meiosis is a unique form of cell division in which cells divide twice but DNA is duplicated only once. Errors in chromosome segregation during meiosis will result in aneuploidy, followed by loss of the conceptus during pregnancy or birth defects. During mitosis, cells utilize a mechanism called the spindle assembly checkpoint (SAC) to ensure faithful chromosome segregation. A similar mechanism has been uncovered for meiosis in the last decade, especially in the past several years. METHODS For this review, we included data and relevant information obtained through a PubMed database search for all articles published in English from 1991 through 2011 which included the term meiosis, spindle assembly checkpoint, or SAC. RESULTS There are 91 studies included. Evidence for the existence of SAC functions in meiosis is provided by studies on the SAC proteins mitotic-arrest deficient-1 (Mad1), Mad2, budding uninhibited by benzimidazole-1 (Bub1), Bub3, BubR1 and Mps1; microtubule-kinetochore

The inhibition of KSP causes mitotic arrest by activating the spindle assembly checkpoint. While transient inhibition of KSP leads to reversible mitotic arrest, prolonged exposure to a KSP inhibitor induces apoptosis. Induction of apoptosis by the KSP inhibitor couples with mitotic slippage. Slippag …

Abstract: The dual-specificity protein kinase monopolar spindle 1 (Mps1) is a central component of the mitotic spindle assembly checkpoint (SAC), a sensing mechanism that prevents anaphase until all chromosomes are bioriented on the metaphase plate. Partial depletion of Mps1 protein levels sensitizes transformed, but not untransformed, human cells to therapeutic doses of the anticancer agent Taxol, making it an attractive novel therapeutic cancer target. We have previously determined the X-ray structure of the catalytic domain of human Mps1 in complex with the anthrapyrazolone kinase inhibitor SP600125. In order to validate distinct inhibitors that target this enzyme and improve our understanding of nucleotide binding site architecture, we now report a biophysical and structural evaluation of the Mps1 catalytic domain in the presence of ATP and the aspecific model kinase inhibitor staurosporine. Collective in silico, enzymatic, and fluorescent screens also identified several new lead quinazoline ...

As a result of checkpoint activation, a signalling cascade is initiated and a number of complexes between the checkpoint components are formed. This leads to the inhibition of the Anaphase Promoting Complex (APC), which is the ubiquitin ligase responsible for targeting mitotic proteins: securing and cyclin B for degradation by the 26S proteasome. The complexes formed include the MCC, or Mitotic Checkpoint Complex, which in fission yeast (Schizosaccharomyces pombe) consists of Mad2, Mad3 checkpoint proteins together with the APC activator, Slp1 (the Cdc20 homologue). The MCC has been shown to bind and inhibit the APC in HeLa cells. In my PhD I focused on the interactions between the MCC and the APC, in particular on Mad3 protein. Mad3 is a conserved checkpoint component, homologous to human BubR1. It carries 2 putative KEN boxes, motifs, which typically target proteins for degradation (like D-boxes). We mutated both KEN boxes in S. pombe Mad3 and show that they are essential for Mad3 checkpoint ...

Strains and media: All yeast strains used in this study are derivatives of FSY182, -183, or -185 (Weinstein and Solomon 1990) except where noted (Table 1). We used standard methods for yeast manipulations (Guthrie and Fink 1991; Solomonet al. 1992).. Plasmid construction: To construct a LYS2-marked plasmid expressing BUB3 under the control of its own promoter, the BUB3 open reading frame was amplified by PCR and ligated into either the pRS317 vector (Sikorski and Hieter 1989) or the YEp426 vector (Maet al. 1987). The upstream primer used to amplify BUB3 (5′-ATAGCGGCCGCGTGACAACCA AGC-3′) contains a NotI site (underlined). The downstream primer (5′-TCTGTCTTCTTGCGTATAGG-3′) contains a SalI site (underlined). These two primers generate a PCR product containing the BUB3 gene as well as ~250 bp of upstream and downstream sequence (~1500 bp). The PCR product was digested with NotI and SalI and ligated into a NotI/SalI-digested pRS317 or YEp426 vector to make pKC52 and pKC74. Both of these ...

Thank you for your interest in spreading the word on Development.. NOTE: We only request your email address so that the person you are recommending the page to knows that you wanted them to see it, and that it is not junk mail. We do not capture any email address.. ...

Paperity: the 1st multidisciplinary aggregator of Open Access journals & papers. Free fulltext PDF articles from hundreds of disciplines, all in one place

ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.atitle=Role%20of%20CENP-A%20NAC/CAD%20network%20in%20spindle%20assembly%20and%20spindle%20checkpoint&rft.date=2008&rft.au=Satyarebala,%20Chilaka&rft.genre=unknown&rft.btitle=Role%20of%20CENP-A%20NAC/CAD%20network%20in%20spindle%20assembly%20and%20spindle% ...

TY - JOUR. T1 - Dependence of Paclitaxel Sensitivity on a Functional Spindle Assembly Checkpoint. AU - Sudo, Tamotsu. AU - Nitta, Masayuki. AU - Saya, Hideyuki. AU - Ueno, Naoto T.. PY - 2004/4/1. Y1 - 2004/4/1. N2 - Paclitaxel stabilizes microtubules, causing mitotic arrest and activating the spindle assembly checkpoint. We determined whether suppression of the checkpoint genes Mad2 and BubR1 affects paclitaxel resistance and whether overexpression of Mad2 protein in checkpoint-defective cells enhances paclitaxel sensitivity. Suppression of Mad2 and BubR1 in paclitaxel-treated cancer cells abolished checkpoint function, resulting in paclitaxel resistance that correlated with suppression of cyclin-dependent kinase-1 activity. In contrast, overexpression of Mad2 in cells with a checkpoint defect attributable to low Mad2 expression restored checkpoint function, resulting in enhanced paclitaxel sensitivity that correlated with enhanced cyclin-dependent kinase-1 activity. However, overexpression of ...

Accurate chromosomal segregation is monitored by the mitotic checkpoint, and an increased rate of chromosomal missegregation leads to chromosomal instability (CIN). Here, we demonstrate that the HBV X protein (HBx) binds BubR1, a component of the mitotic checkpoint complex and co-localizes with BubR1 at the kinetochores. HBx binding to BubR1 attenuates the association between BubR1 and CDC20, an activator of the anaphase-promoting complex/cyclosome (APC/C) and induces slippage of mitotic arrest in the presence of microtubule poisons. In addition, HBx binding to BubR1 results in the accumulation of lagging chromosomes and chromosome bridges. In contrast, a C-terminally truncated HBx mutant (HBx(1-100)) fails to bind BubR1 and does not cause aberrant chromosomal segregation. This provides a novel mechanism for dysregulation of the mitotic checkpoint by a viral pathogen linking it to the accumulation of chromosomal instability in HBV-associated hepatocarcinogenesis.. ...

CENP-E has previously been shown to bind to kinetochores and microtubules and stabilize the interaction between them (Putkey et al., 2002), thereby contributing to silencing mitotic checkpoint signaling. Now, we have shown that CENP-E is also required in vitro and in vivo for maximal mitotic checkpoint signal generation at individual kinetochores, and is thus bifunctional in checkpoint signaling. We find that CENP-E stimulates recruitment of its binding partner BubR1 to kinetochores in HeLa cells and in MEFs. In addition, CENP-E directly stimulates the kinase (and autokinase) activity of BubR1 in vitro and in primary MEFs (Fig. 8). The simplest view is that CENP-E amplifies a basal mitotic checkpoint that is sufficient for long-term arrest when large numbers of kinetochores are unattached, but is of insufficient strength for one or a few kinetochores to produce a checkpoint signal that is able to sustain mitotic arrest.. Several lines of evidence offer strong support for our proposal that CENP-E ...

The molecular role of the centrosome in the spindle checkpoint has been debated for some time. Müller et al. have now identified a function for a subset of core centrosomal proteins, namely their involvement in the spindle checkpoint. γ-tubulin ring proteins are functionally and biochemically integrated into checkpoint control, together with two of the major players in this pathway, BubR1 and Cdc20. However, the function of the γ-tubulin ring components was not linked to centrosome integrity, nor did it require localization to this organelle.. H. Müller, M.-L. Fogeron, V. Lehmann, H. Lehrach, B. M. H. Lange, A centrosome-independent role for γ-TuRC proteins in the spindle assembly checkpoint. Science 314, 654-657 (2006). [Abstract] [Full Text]. ...

Exit from mitosis requires the degradation of regulatory proteins including the mitotic cyclins and securin through ubiquitination by the anaphase promoting complex bound to Cdc20 or Cdh1. Cdc20-APC is regulated through inhibition by the spindle assembly checkpoint protein MAD2. Knowledge of Cdh1-APC regulation is limited to the phosphorylation-dependent dissociation of Cdh1 from APC. A novel means of regulating Cdh1 by the MAD2-related gene, MAD2L2, is reported. MAD2L2 specifically binds and inhibits Cdh1-APC, paralleling the effect of MAD2 on Cdc20. It is suggested that MAD2L2 and MAD2 inhibit the release of substrates from APC and a mechanism of inhibition is proposed (Pfleger, 2001a). The specificity of ubiquitin-mediated protein degradation with regard to the selection of substrates to be polyubiquitinated has only been determined rather recently. Substrate targeting by the N-end rule and HECT (homology to E6AP carboxyl terminus) domain ubiquitin ligases occurs through substrate-specific ...

Germline mutations in the spindle assembly checkpoint genes are risk factors for colorectal cancer, reports the latest issue of Gastroenterology.. ...

UCL Discovery is UCLs open access repository, showcasing and providing access to UCL research outputs from all UCL disciplines.

A method and system for monitoring performance of a processing system, the processing system including a plurality of performance monitor counters (PMCs) and at least one monitor mode control register (MMCR) to configure the operations of at least one of the PMCs, includes identifying misaligned data items, and determining a performance penalty of misaligned data accesses during a predetermined sampling period.

Cell division in mitosis and meiosis is governed by evolutionary highly conserved protein kinases and phosphatases, controlling the timely execution of key events such as nuclear envelope breakdown, spindle assembly, chromosome attachment to the spindle and chromosome segregation, and cell cycle exit. In mitosis, the spindle assembly checkpoint (SAC) controls the proper attachment to and alignment of chromosomes on the spindle. The SAC detects errors and induces a cell cycle arrest in metaphase, preventing chromatid separation. Once all chromosomes are properly attached, the SAC-dependent arrest is relieved and chromatids separate evenly into daughter cells. The signaling cascade leading to checkpoint arrest depends on several protein kinases that are conserved from yeast to man. In meiosis, haploid cells containing new genetic combinations are generated from a diploid cell through two specialized cell divisions. Though apparently less robust, SAC control also exists in meiosis. Recently, it has emerged

TY - JOUR. T1 - Plk1 bound to Bub1 contributes to spindle assembly checkpoint activity during mitosis. AU - Ikeda, Masanori. AU - Tanaka, Kozo. N1 - Funding Information: The authors thank K. Mizuno for YFP-Plk1, J.G. Deluca for Hec1-GFP, M. Lampson for mCherry-Knl1 and Hec1-mCherry-Plk1, G.J. Kops for anti-phospho-Mps1 antibody against T676 and anti-phospho-BubR1 antibody against T680, Y. Watanabe for anti-phospho-Knl1 antibody against T875 and T. Hirota for mCherry-Mis12. We also thank members of the K.T. laboratory for discussions and A. Harata for technical assistance. This work was supported by JSPS KAKENHI Grant Numbers 24370078, 26640067, 26870054, 15H04368, and 16K14604; MEXT KAKENHI Grant Numbers 24114502 and 26114702; and grants from the Takeda Science Foundation, Princess Takamatsu Cancer Research Fund (10-24210).. PY - 2017/12/1. Y1 - 2017/12/1. N2 - For faithful chromosome segregation, the formation of stable kinetochore-microtubule attachment and its monitoring by the spindle ...

Spindle checkpoint proteins monitor the interaction of the spindle apparatus with the kinetochores, halting anaphase even if the microtubule attachment of only a single chromosome is altered. In this study, we show that Bub3p of Saccharomyces cerevisiae, an evolutionarily conserved spindle checkpoint protein, exhibits distinct interactions with an altered or defective kinetochore(s). We show for the first time that green fluorescent protein-tagged S. cerevisiae Bub3p (Bub3-GFP) exhibits not only a diffuse nuclear localization pattern but also forms distinct nuclear foci in unperturbed growing and G2/M-arrested cells. As Bub3-GFP foci overlap only a subset of kinetochores, we tested a model in which alterations or defects in kinetochore or spindle integrity lead to the distinct enrichment of Bub3p at these structures. In support of our model, kinetochore-associated Bub3-GFP is enriched upon activation of the spindle checkpoint due to nocodazole-induced spindle disassembly, overexpression of the

Essential component of the mitotic checkpoint. Required for normal mitosis progression. The mitotic checkpoint delays anaphase until all chromosomes are properly attached to the mitotic spindle. One of its checkpoint functions is to inhibit the activity of the anaphase-promoting complex/cyclosome (APC/C) by blocking the binding of CDC20 to APC/C, independently of its kinase activity. The other is to monitor kinetochore activities that depend on the kinetochore motor CENPE. Required for kinetochore localization of CENPE. Negatively regulates PLK1 activity in interphase cells and suppresses centrosome amplification. Also implicated in triggering apoptosis in polyploid cells that exit aberrantly from mitotic arrest. May play a role for tumor suppression ...

The Spindle Assembly Checkpoint (SAC) works to maintain the genomic balance by monitoring the correctness of attachments between the chromosomes and microtubules during early cell division (mitosis). Importantly, chromosome missegregation and genomic instability is caused by defects in SAC function, which can lead to cell transformation and cancer. Moreover, malfunction of SAC can confer resistance to microtubule-targeting drugs (MTAs) such as paclitaxel. The identification and functional characterization of novel SAC regulating biomolecules and analysis of their expression profiles in tumor cells may in the future facilitate improved cancer diagnosis and predict patients response to MTA therapy. The microRNA- (miRNA) and protein phosphatase-mediated regulation of mitotic signaling were investigated in my thesis. First, to identify new miRNAs that regulate SAC signaling, a cell-based high-throughput screen (HTS) was performed to test the ability of 810 different pre-miRNAs to override a drug ...

Research Statement. Cell division is a critical biological event regulated by the spindle assembly checkpoint (SAC), an intricate signalling mechanism of higher organisms that ensures the arrest of cells in mitosis until defects in chromosome attachment are repaired. Mistakes in the SAC can lead to the loss, gain or rearrangements of the genetic material, which is the main cause of spontaneous miscarriage; the origin of birth and developmental defects; genome instability; cancer; and of diverse age-associated pathologies including sarcopenia, cardiac arrhythmias, arterial wall stiffening, impaired wound healing and dermal thinning. In essence, I am trying to understand: a) how the SAC, the kinetochore and microtubules work together to ensure the accurate separation of chromosomes when cells divide; b) details of how the import into the nucleus of certain SAC proteins by nuclear transport receptors regulates the process; c) explore ways in which the structural and mechanistic understanding of the ...

Equal bipolar distribution of kinetochores requires oligomerization of the Dam1 complexTime-lapse images of spindle poles (Spc110-mCherry, top row), kinetochore

InterPro provides functional analysis of proteins by classifying them into families and predicting domains and important sites. We combine protein signatures from a number of member databases into a single searchable resource, capitalising on their individual strengths to produce a powerful integrated database and diagnostic tool.

ORDERED temporal degradation of proteins is an important regulatory mechanism that controls progression through the eukaryotic cell cycle (Reed 2006). The anaphase promoting complex/cyclosome (APC/C) is the E3 subunit of an ubiquitin-conjugating enzyme composed of at least thirteen subunits that targets proteins for proteolysis during the cell cycle (Peters 2006). APC/C function is critical for progression through mitosis where it degrades Pds1 (securin in higher eukaryotic cells) and other substrates to promote anaphase and the exit from mitosis (Pines 2006). APC/C cofactors Cdc20 and Cdh1 are important for conferring substrate specificity during different stages in the cell cycle (Peters 2006). It is unclear, however, how the APC/C chooses substrates for ubiquitylation and the specific role of each subunit in this process (Acquaviva and Pines 2006). The spindle assembly checkpoint (SAC) ensures the formation of a bipolar spindle and proper attachment of kinetochores (Lew and Burke 2003). The ...

In the mitotic cell cycle, it is only when all chromosomes have appropriately established bipolar attachment to the mitotic spindle that the metaphase-to-anaphase transition can occur (Chen, 2004; Yu and Tang, 2005). Because kinetochores capture microtubules in a stochastic manner, three types of erroneous kinetochore attachments, including monotelic (only one of the sister kinetochores is attached to one spindle pole), syntelic (both sister kinetochores are attached to the same spindle pole), and merotelic (one kinetochore is attached to two opposing spindle poles) attachment, frequently occur (Gregan et al., 2011). Thus, there must be a surveillance mechanism that prevents the precocious separation of sister chromatids until all the improper kinetochore attachments are corrected, ensuring the fidelity of chromosome segregation (Meraldi and Sorger, 2005; Yu and Tang, 2005). The spindle assembly checkpoint (SAC) is such a mechanism that delays anaphase onset when any kinetochore is not properly ...

Each mitotic chromosome is constituted by two sister chromatids whose correct segregation to the daughter cells is ensured by amphitelic attachment, in which the two sister kinetochores (KTs) are attached to microtubules (MTs) from opposite mitotic spindle poles. KT mis-attachments can occur in early mitosis and cause chromosome mis-segregation and aneuploidy if not corrected. These mis-attachments include monotelic (one attached and one unattached sister KT), syntelic (both sister KTs attached to the same spindle pole), and merotelic (a single KT attached to MTs from opposite spindle poles) attachments. A biochemical pathway named the Spindle Assembly Checkpoint (SAC) is responsible for delaying anaphase onset to allow correction of KT mis-attachments. SAC activation is believed to occur due to KT localization of certain SAC proteins and/or lack of tension, but only monotelic attachment has been proven to activate the SAC. To determine if and how other KT mis-attachments may activate the SAC, ...

Extensive biochemical and molecular analyses have shown that BubR1 plays a central role in spindle checkpoint activation (5 , 15 , 16) . It both coordinates the interaction of Bub3, Mad1, Mad2, and CENP-E with kinetochores and contributes to inhibition of APC activity during activation of this checkpoint. The APC is an E3 ubiquitin ligase that mediates the polyubiquitination of securin, thereby targeting it for degradation by the proteosome (16) . Securin binds to and inhibits the proteolytic activity of separase, which destroys the link between sister chromatids by cleaving the chromatid cohesin factor Scc1. Degradation of securin is required for the separation of sister chromatids during mitosis. Reduced levels of securin in BubR1+/− MEFs are closely correlated with BubR1 deficiency as well as with its activation status (Fig. 1C) ⇓ . Moreover, down-regulation of BubR1 via RNA interference resulted in almost complete disappearance of securin (Fig. 1D) ⇓ , strongly suggesting that BubR1 ...

The Chk1 kinase is essential for the DNA damage-induced G2 checkpoint and restrains entry into mitosis ( 18, 21). The development of the Chk1 kinase inhibitor UCN-01, although not entirely specific, has allowed to establish the therapeutic concept of G2 checkpoint abrogation that potentiates tumor cell killing selectively in p53-deficient tumor cells ( 16, 17, 19, 20, 24). Consequently, several phase I clinical trials currently explore this concept by combining various DNA-damaging drugs with UCN-01 (e.g.; ref. 24). However, the mechanisms and requirements of cell death on G2 checkpoint abrogation remained largely unknown. We have addressed these questions and established the following points: (a) UCN-01-mediated G2 checkpoint abrogation induces entry into mitosis, which is associated with a metaphase-like arrest that requires the mitotic spindle checkpoint. (b) The spindle checkpoint protein Mad2 is required for the induction of apoptosis in response to UCN-01 treatment. (c) The chromosomal ...

Here, we found that SphK1 and its product S1P regulate mitosis. SphK1 promoted proper mitotic progression in a SAC-dependent manner, whereas increased SphK1 activity accelerated mitosis (Movie S1 and Movie S2). S1P overrode the mitotic spindle checkpoint, led to premature mitotic exit, and induced chromosome segregation defects through a pathway involving S1P5 and phosphatidylinositol 3-kinase (PI3K)-AKT signaling that was at least partially mediated by Polo-like kinase 1 (PLK1).. In summary, our study uncovers a previously unknown role for SphK1-S1P-S1P5 signaling in controlling proper mitotic progression through prometaphase to the metaphase-to-anaphase transition. More generally, our findings support the concept that cellular micro- environment plays an important role in coordination of mitosis and paves the way for future studies evaluating the relationship between extracellular signals, mitotic progression, and chromosomal stability.. ...

BISAC: MED062000. This book presents original results on the leading edge of cancer research. Chapter One presents an overview of the opportunities and challenges that influence the participation of personalized approach of giving the right drug at the right dose to the right patient. Chapter Two examines malignant mesothelioma. Chapter Three reviews the role of heat-shock proteins and chaperonins in the pathogenesis and progression of cancer. Chapter Four discusses the biosynthesis of LeX family glycosphingolipids and its gene regulation. Chapter Five summarizes how chromosome segregation is accurately controlled and how spindle assembly checkpoint (SAC) monitors this process to maintain segregation fidelity. Chapter Six reviews significant novel findings and the early clinical development of a CD26-targeted therapy for malignant pleural mesothelioma (MPM), and advances that can lead to a more hopeful future for MPM patients. Chapter Seven reviews the pathophysiology and novel treatment ...

The protein encoded by this gene was identified as a binding protein of the MAD2 mitotic arrest deficient-like 1 (MAD2/MAD2L1). MAD2 is a key component of the spindle checkpoint that delays the onset of anaphase until all the kinetochores are attached to the spindle. This protein may interact with the spindle checkpoint and coordinate cell cycle events in late mitosis. Alternatively spliced transcript variants encoding distinct isoforms have been observed. [provided by RefSeq, Jul 2008 ...

Release of fluorescent Mad2 particles from kinetochores. Fluorescent XMad2 particles were released from the kinetochore and transported towards the spindle pole

Summary: Abscisic acid is used as a chemically induced dimeriser (CID) to bring together Mph1 kinase and Spc7 and initiate spindle checkpoint signalling in vivo. Simply washing out the abscisic acid enables checkpoint silencing to be studied. ...

Hassalli kehad (lad corpuscula thymi) on selgroogsete loomade tüümuse säsis (nii normaalses kui patoloogilises) olevad varieeruva suuruse ja arenguastmetega kindla päritoluta rakkude rühmad. Hassalli kehade areng ja päritolu on ebaselged, arvatakse et kehad moodustatakse tüümuse epiteelirakkudest. Hasalli kehade moodustumise (ilmumise) kohta inimloote tüümuses on andmed varieeruvad, neid on tuvastatud 8.-16. rasedusnädalani. Hasalli kehad on tuvastatud osadel roomajatel, kuid nende olemasolu madude tüümuses on arvatavasti vähe uuritud. On pakutud, et Hassalli kehade ülesandeks võib olla kas surnud tümotsüütide lõhustamine või ka alles arenevate tümotsüütide küpsemise tagamine. Hassalli kehi ümbritsevad lümfisooned. Lamba tüümuses on tuvastatud Hassalli kehade lõhustamine makrofaagide poolt - lamba embrüo tüümuses toimub suurenenud Hassalli kehade lõhustumine makrofaagide poolt kas tiinuse lõppedes või kohe peale lambatalle sündi ning asendatakse uute Hassalli ...