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Jianjun Luo, Xiexiong Deng, Christopher Buehl, Xinjing Xu, Min-Hao Kuo
To ensure genome stability during cell division, all chromosomes must attach to spindles emanating from the opposite spindle pole bodies before segregation. The tension between sister chromatids generated by the poleward pulling force is an integral part of chromosome bi-orientation. In budding yeast, the residue Gly44 of histone H3 is critical for retaining the conserved Shugoshin protein Sgo1p at the pericentromeres for monitoring the tension status during mitosis. Studies carried out in this work showed that Lys42, Gly44, and Thr45 of H3 form the core of a tension sensing motif, TSM...
September 26, 2016: Genetics
Rabia Faridi, Atteeq U Rehman, Robert J Morell, Penelope L Friedman, Leigh Demain, Sana Zahra, Asma Ali Khan, Dalia Tohlob, Muhammad Zaman Assir, Glenda Beaman, Shaheen N Khan, William G Newman, Sheikh Riazuddin, Thomas B Friedman
Perrault syndrome (PS) is a genetically heterogeneous disorder characterized by primary ovarian insufficiency (POI) in females and sensorineural hearing loss in males and females. In many PS subjects, causative variants have not been found in the five reported PS genes. The objective of this study was to identify the genetic cause of PS in an extended consanguineous family with six deaf individuals. Whole exome sequencing (WES) was completed on four affected members of a large family, and variants and co-segregation was confirmed by Sanger sequencing...
September 15, 2016: Clinical Genetics
Yuko Murakami-Tonami, Haruna Ikeda, Ryota Yamagishi, Mao Inayoshi, Shiho Inagaki, Satoshi Kishida, Yosuke Komata, Jan Koster, Ichiro Takeuchi, Yutaka Kondo, Tohru Maeda, Yoshitaka Sekido, Hiroshi Murakami, Kenji Kadomatsu
Shugoshin 1 (SGO1) is required for accurate chromosome segregation during mitosis and meiosis; however, its other functions, especially at interphase, are not clearly understood. Here, we found that downregulation of SGO1 caused a synergistic phenotype in cells overexpressing MYCN. Downregulation of SGO1 impaired proliferation and induced DNA damage followed by a senescence-like phenotype only in MYCN-overexpressing neuroblastoma cells. In these cells, SGO1 knockdown induced DNA damage, even during interphase, and this effect was independent of cohesin...
2016: Scientific Reports
H Y Yamada, G Kumar, Y Zhang, E Rubin, S Lightfoot, W Dai, C V Rao
Mitotic error-mediated chromosome instability (CIN) can lead to aneuploidy, chromothripsis, DNA damage and/or whole chromosome gain/loss. CIN may prompt rapid accumulation of mutations and genomic alterations. Thus, CIN can promote carcinogenesis. This CIN process results from a mutation in certain genes or environmental challenge such as smoking, and is highly prevalent in various cancers, including lung cancer. A better understanding of the effects of CIN on carcinogenesis will lead to novel methods for cancer prevention and treatment...
2016: Oncogenesis
Jiao Wang, Zhizhi Wang, Tingting Yu, Huan Yang, David M Virshup, Geert J P L Kops, Sang Hyun Lee, Weihong Zhou, Xin Li, Wenqing Xu, Zihe Rao
Protein phosphatase 2A (PP2A) accounts for the majority of total Ser/Thr phosphatase activities in most cell types and regulates many biological processes. PP2A holoenzymes contain a scaffold A subunit, a catalytic C subunit, and one of the regulatory/targeting B subunits. How the B subunit controls PP2A localization and substrate specificity, which is a crucial aspect of PP2A regulation, remains poorly understood. The kinetochore is a critical site for PP2A functioning, where PP2A orchestrates chromosome segregation through its interactions with BubR1...
July 2016: Protein & Cell
Samantha J Williams, Ariane Abrieu, Ana Losada
Centromeric chromatin containing the histone H3 variant centromere protein A (CENP-A) directs kinetochore assembly through a hierarchical binding of CENPs, starting with CENP-C and CENP-T. Centromeres are also the chromosomal regions where cohesion, mediated by cohesin, is most prominently maintained in mitosis. While most cohesin dissociates from chromosome arms in prophase, Shugoshin 1 (Sgo1) prevents this process at centromeres. Centromeric localization of Sgo1 depends on histone H2A phosphorylation by the kinase Bub1, but whether additional interactions with kinetochore components are required for Sgo1 recruitment is unclear...
April 26, 2016: Chromosoma
Susumu Uchiyama, Kiichi Fukui
After replication of genomic DNA during the S phase, 2 chromatids hold together longitudinally. When cells enter mitosis, the paired sister chromatids start to condense and then segregate into individual chromatids except for the centromeric region. Upon attachment of microtubules to the kinetochore, subsequent pulling of the 2 sister chromatids by the spindles towards opposite poles results in 2 completely separated chromatids. Besides more than 100 kinds of kinetochore proteins, several key proteins such as cohesin, separase, shugoshin, and condensin contribute to chromatid cohesion and segregation...
2015: Cytogenetic and Genome Research
Hong Liu
The major role of RNA polymerase II (RNAP II) is to generate mRNAs. I recently uncovered a novel function of RNAP II in chromosome segregation in mitosis, installing the cohesin protector, Shugoshin, at centromeres. Here I will discuss the current understanding of RNAP II-dependent centromeric transcription in mitosis.
2016: Transcription
Anna P Baron, Conrad von Schubert, Fabien Cubizolles, Gerhard Siemeister, Marion Hitchcock, Anne Mengel, Jens Schröder, Amaury Fernández-Montalván, Franz von Nussbaum, Dominik Mumberg, Erich A Nigg
The kinase Bub1 functions in the spindle assembly checkpoint (SAC) and in chromosome congression, but the role of its catalytic activity remains controversial. Here, we use two novel Bub1 inhibitors, BAY-320 and BAY-524, to demonstrate potent Bub1 kinase inhibition both in vitro and in intact cells. Then, we compared the cellular phenotypes of Bub1 kinase inhibition in HeLa and RPE1 cells with those of protein depletion, indicative of catalytic or scaffolding functions, respectively. Bub1 inhibition affected chromosome association of Shugoshin and the chromosomal passenger complex (CPC), without abolishing global Aurora B function...
2016: ELife
Chinthalapally V Rao, Saira Sanghera, Yuting Zhang, Laura Biddick, Arun Reddy, Stan Lightfoot, Naveena B Janakiram, Altaf Mohammed, Wei Dai, Hiroshi Y Yamada
Colon cancer is the second most lethal cancer and is predicted to claim 49,700 lives in the United States this year. Chromosome instability (CIN) is observed in 80% to 90% of colon cancers and is thought to contribute to colon cancer progression and recurrence. To investigate the impact of CIN on colon cancer development, we developed shugoshin-1 (Sgo1) haploinsufficient (-/+) mice, an animal model focusing on mitotic error-induced CIN. In this study, we analyzed signature changes in the colonic transcriptome of Sgo1(-/+) mice to examine the molecular events underlying the altered carcinogenesis profiles in Sgo1(-/+) mice...
February 1, 2016: Cancer Research
Sanki Tashiro, Tetsuya Handa, Atsushi Matsuda, Takuto Ban, Toru Takigawa, Kazumi Miyasato, Kojiro Ishii, Kazuto Kugou, Kunihiro Ohta, Yasushi Hiraoka, Hisao Masukata, Junko Kanoh
A chromosome is composed of structurally and functionally distinct domains. However, the molecular mechanisms underlying the formation of chromatin structure and the function of subtelomeres, the telomere-adjacent regions, remain obscure. Here we report the roles of the conserved centromeric protein Shugoshin 2 (Sgo2) in defining chromatin structure and functions of the subtelomeres in the fission yeast Schizosaccharomyces pombe. We show that Sgo2 localizes at the subtelomeres preferentially during G2 phase and is essential for the formation of a highly condensed subtelomeric chromatin body 'knob'...
2016: Nature Communications
Wing Ki Wong, Terrenz Kelly, Jingjing Li, Hoi Tang Ma, Randy Y C Poon
Shugoshin (SGO1) plays a pivotal role in sister chromatid cohesion during mitosis by protecting the centromeric cohesin from mitotic kinases and WAPL. Mammalian cells contain at least 6 alternatively spliced isoforms of SGO1. The relationship between the canonical SGO1A with shorter isoforms including SGO1C remains obscure. Here we show that SGO1C was unable to replace the loss of SGO1A. Instead, expression of SGO1C alone induced aberrant mitosis similar to depletion of SGO1A, promoting premature sister chromatid separation, activation of the spindle-assembly checkpoint, and mitotic arrest...
2015: Cell Cycle
Lisa Mohr, Johannes Buheitel, Laura Schöckel, Dorothea Karalus, Bernd Mayer, Olaf Stemmann
Separation of human sister chromatids involves the removal of DNA embracing cohesin ring complexes. Ring opening occurs by prophase-pathway-dependent phosphorylation and separase-mediated cleavage, with the former being antagonized at centromeres by Sgo1-dependent PP2A recruitment. Intriguingly, prophase pathway signaling and separase's proteolytic activity also bring about centriole disengagement, whereas Sgo1 is again counteracting this licensing step of later centrosome duplication. Here, we demonstrate that alternative splice variants of human Sgo1 specifically and exclusively localize and function either at centromeres or centrosomes...
September 29, 2015: Cell Reports
Yuji Tanno, Hiroaki Susumu, Miyuki Kawamura, Haruhiko Sugimura, Takashi Honda, Yoshinori Watanabe
Chromosomal instability (CIN) is a major trait of cancer cells and a potent driver of tumor progression. However, the molecular mechanisms underlying CIN still remain elusive. We found that a number of CIN(+) cell lines have impairments in the integrity of the conserved inner centromere-shugoshin (ICS) network, which coordinates sister chromatid cohesion and kinetochore-microtubule attachment. These defects are caused mostly by the loss of histone H3 lysine 9 trimethylation at centromeres and sometimes by a reduction in chromatin-associated cohesin; both pathways separately sustain centromeric shugoshin stability...
September 11, 2015: Science
C van de Werken, M Avo Santos, J S E Laven, C Eleveld, B C J M Fauser, S M A Lens, E B Baart
STUDY QUESTION: Are the kinase feedback loops that regulate activation and centromeric targeting of the chromosomal passenger complex (CPC), functional during mitosis in human embryos? SUMMARY ANSWER: Investigation of the regulatory kinase pathways involved in centromeric CPC targeting revealed normal phosphorylation dynamics of histone H2A at T120 (H2ApT120) by Bub1 kinase and subsequent recruitment of Shugoshin, but phosphorylation of histone H3 at threonine 3 (H3pT3) by Haspin failed to show the expected centromeric enrichment on metaphase chromosomes in the zygote...
October 2015: Human Reproduction
Hong Liu, Qianhui Qu, Ross Warrington, Allyson Rice, Ningyan Cheng, Hongtao Yu
Human sister chromatids at metaphase are primarily linked by centromeric cohesion, forming the iconic X shape. Premature loss of centromeric cohesion disrupts orderly mitotic progression. Shugoshin (Sgo1) binds to and protects cohesin at inner centromeres. The kinetochore kinase Bub1 phosphorylates histone H2A at T120 (H2A-pT120) and recruits Sgo1 to kinetochores, 0.5 μm from inner centromeres. Here, we show that Sgo1 is a direct reader of the H2A-pT120 mark. Bub1 also recruits RNA polymerase II (Pol II) to unattached kinetochores and promotes active transcription at mitotic kinetochores...
August 6, 2015: Molecular Cell
Hiroshi Y Yamada, Yuting Zhang, Arun Reddy, Altaf Mohammed, Stan Lightfoot, Wei Dai, Chinthalapally V Rao
A major etiological risk factor for hepatocellular carcinoma (HCC) is infection by Hepatitis viruses, especially hepatitis B virus and hepatitis C virus. Hepatitis B virus and hepatitis C virus do not cause aggressive activation of an oncogenic pathway, but they transactivate a broad array of genes, cause chronic inflammation, and, through interference with mitotic processes, lead to mitotic error-induced chromosome instability (ME-CIN). However, how ME-CIN is involved in the development of HCC remains unclear...
April 2015: Carcinogenesis
Lyu-Han Wang, Chia-Jui Yen, Tian-Neng Li, Sabine Elowe, Wen-Ching Wang, Lily Hui-Ching Wang
Shugoshin-like protein 1 (Sgo1) is an essential protein in mitosis; it protects sister chromatid cohesion and thereby ensures the fidelity of chromosome separation. We found that the expression of Sgo1 mRNA was relatively low in normal tissues, but was upregulated in 82% of hepatocellular carcinoma (HCC), and correlated with elevated alpha-fetoprotein and early disease onset of HCC. The depletion of Sgo1 reduced cell viability of hepatoma cell lines including HuH7, HepG2, Hep3B, and HepaRG. Using time-lapse microscopy, we showed that hepatoma cells were delayed and ultimately die in mitosis in the absence of Sgo1...
February 10, 2015: Oncotarget
Jihye Kim, Kei-ichiro Ishiguro, Aya Nambu, Bungo Akiyoshi, Shihori Yokobayashi, Ayano Kagami, Tadashi Ishiguro, Alberto M Pendas, Naoki Takeda, Yogo Sakakibara, Tomoya S Kitajima, Yuji Tanno, Takeshi Sakuno, Yoshinori Watanabe
The kinetochore is the crucial apparatus regulating chromosome segregation in mitosis and meiosis. Particularly in meiosis I, unlike in mitosis, sister kinetochores are captured by microtubules emanating from the same spindle pole (mono-orientation) and centromeric cohesion mediated by cohesin is protected in the following anaphase. Although meiotic kinetochore factors have been identified only in budding and fission yeasts, these molecules and their functions are thought to have diverged earlier. Therefore, a conserved mechanism for meiotic kinetochore regulation remains elusive...
January 22, 2015: Nature
Mayumi Hamasaki, Shigeru Matsumura, Ayaka Satou, Chisato Takahashi, Yukako Oda, Chika Higashiura, Yasushi Ishihama, Fumiko Toyoshima
Cell division is controlled by a multitude of protein enzymes, but little is known about roles of metabolites in this mechanism. Here, we show that pregnenolone (P5), a steroid that is produced from cholesterol by the steroidogenic enzyme Cyp11a1, has an essential role in centriole cohesion during mitosis. During prometa-metaphase, P5 is accumulated around the spindle poles. Depletion of P5 induces multipolar spindles that result from premature centriole disengagement, which are rescued by ectopic introduction of P5, but not its downstream metabolites, into the cells...
December 18, 2014: Chemistry & Biology
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