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mitosis , meiosis

Tadashi Ishiguro, Kana Tanabe, Yuki Kobayashi, Shinsuke Mizumoto, Motomu Kanai, Shigehiro A Kawashima
Post-translational modifications of histones, such as acetylation and phosphorylation, are highly conserved in eukaryotes and their combination enables precise regulation of many cellular functions. Recent studies using mass spectrometry have revealed various non-acetyl acylations in histones, including malonylation and succinylation, which change the positive charge of lysine into a negative one. However, the molecular function of histone malonylation or succinylation is poorly understood. Here, we discovered the functions of malonylation in histone H2A at lysine 119 (H2A-K119) in chromosome segregation during mitosis and meiosis...
May 16, 2018: Scientific Reports
Margarita R Hernandez, Michael B Davis, Jianhao Jiang, Elizabeth A Brouhard, Aaron F Severson, Györgyi Csankovszki
Condensin complexes are key determinants of higher-order chromatin structure and are required for mitotic and meiotic chromosome compaction and segregation. We identified a new role for condensin in the maintenance of sister chromatid cohesion during C. elegans meiosis. Using conventional and stimulated emission depletion (STED) microscopy we show that levels of chromosomally-bound cohesin were significantly reduced in dpy-28 mutants, which lack a subunit of condensin I. SYP-1, a component of the synaptonemal complex central region, was also diminished, but no decrease in the axial element protein HTP-3 was observed...
May 16, 2018: PLoS Genetics
Stanley Nithianantham, Francis J McNally, Jawdat Al-Bassam
The reorganization of microtubules in mitosis, meiosis and development requires the microtubule-severing activity of katanin.  Katanin is a heterodimer composed of an ATPase Associated with diverse cellular Activities (AAA) subunit and a regulatory subunit. Microtubule severing requires ATP hydrolysis by katanin's conserved AAA ATPase domains. Whereas other AAA ATPases form stable hexamers, we show that katanin only forms monomer or dimers of heterodimers in solution.  Katanin oligomers consistent with hexamers of heterodimers or heterododecamers were only observed for an ATP hydrolysis deficient mutant in the presence of ATP...
May 11, 2018: Journal of Biological Chemistry
Gabriel M Gihana, Tiffany R Musser, Oscar Thompson, Soni Lacefield
We investigated how Saccharomyces cerevisiae coordinate polarization, budding, and anaphase during a unique developmental program called return to growth (RTG) in which cells in meiosis return to mitosis upon nutrient shift. Cells reentering mitosis from prophase I deviate from the normal cell cycle by budding in G2 instead of G1. We found that cells do not maintain the bipolar budding pattern, a characteristic of diploid cells. Furthermore, strict temporal regulation of M-phase cyclin-dependent kinase (CDK; M-CDK) is important for polarity establishment and morphogenesis...
May 9, 2018: Journal of Cell Biology
Peter G Wolf, Alexander Cuba Ramos, Julia Kenzel, Brigitte Neumann, Olaf Stemmann
The DNA embracing, ring-shaped, multiprotein complex cohesin mediates sister chromatid cohesion and is stepwise displaced in mitosis by Wapl and Separase to facilitate anaphase. Proper regulation of chromosome cohesion throughout meiosis is critical to prevent formation of aneuploid gametes, which are associated with trisomies and infertility in humans. Studying cohesion in meiocytes is complicated by their difficult experimental amenability and the absence of cohesin turnover. Here, we use cultured somatic cells to unravel fundamental aspects of meiotic cohesin...
May 3, 2018: Journal of Cell Science
Danica Drpic, Ana C Almeida, Paulo Aguiar, Fioranna Renda, Joana Damas, Harris A Lewin, Denis M Larkin, Alexey Khodjakov, Helder Maiato
Chromosome missegregation during mitosis or meiosis is a hallmark of cancer and the main cause of prenatal death in humans. The gain or loss of specific chromosomes is thought to be random, with cell viability being essentially determined by selection. Several established pathways including centrosome amplification, sister-chromatid cohesion defects, or a compromised spindle assembly checkpoint can lead to chromosome missegregation. However, how specific intrinsic features of the kinetochore-the critical chromosomal interface with spindle microtubules-impact chromosome segregation remains poorly understood...
April 20, 2018: Current Biology: CB
Jun Yu Zhang, Shan Lv, Hui Min Niu, An Min Lei
The mammalian oocyte maturation process consists of two consecutive asymmetric divisions, and produces three daughter cells of vastly different sizes: one larger egg cell and two smaller polar bodies. Asymmetric division is a typical feature of mammalian oocyte meiosis that results in a highly polar egg cell. The mitosis of the cell after fertilization exhibits restored symmetric division, but the polarity characteristics formed during meiosis of oocytes are preserved and affect the polarity of early embryos...
April 20, 2018: Yi Chuan, Hereditas
Ignacio Flor-Parra, Ana Belén Iglesias-Romero, Silvia Salas-Pino, Rafael Lucena, Juan Jimenez, Rafael R Daga
In metazoans, the nuclear envelope (NE) breakdown (NEBD) occurs during "open" mitosis and meiosis. In the fission yeast Schizosaccharomyces pombe, the mitosis and the first meiotic division (MI) are "closed," during which the NE is maintained. Intriguingly, during the second meiotic division (MII), the NE is also maintained, but nuclear and cytoplasmic molecules are mixed similarly to open mitosis, a phenomenon of unknown biological significance called "virtual" NEBD (vNEBD). Here, we show that importin-α-dependent nucleocytoplasmic transport regulates spindle disassembly late in anaphase B at MI, as previously reported for mitosis...
April 24, 2018: Cell Reports
Joseph M Varberg, Sue L Jaspersen
In fission yeast, the nuclear envelope (NE) remains intact during mitosis and meiosis I but is compromised during meiosis II. In this issue of Cell Reports, Flor-Parra et al. (2018) demonstrate that this NE alteration regulates meiosis II spindle disassembly and the ploidy of meiotic products.
April 24, 2018: Cell Reports
Jana Link, Dimitra Paouneskou, Maria Velkova, Anahita Daryabeigi, Triin Laos, Sara Labella, Consuelo Barroso, Sarai Pacheco Piñol, Alex Montoya, Holger Kramer, Alexander Woglar, Antoine Baudrimont, Sebastian Mathias Markert, Christian Stigloher, Enrique Martinez-Perez, Alexander Dammermann, Manfred Alsheimer, Monique Zetka, Verena Jantsch
Meiotic chromosome movement is important for the pairwise alignment of homologous chromosomes, which is required for correct chromosome segregation. Movement is driven by cytoplasmic forces, transmitted to chromosome ends by nuclear membrane-spanning proteins. In animal cells, lamins form a prominent scaffold at the nuclear periphery, yet the role lamins play in meiotic chromosome movement is unclear. We show that chromosome movement correlates with reduced lamin association with the nuclear rim, which requires lamin phosphorylation at sites analogous to those that open lamina network crosslinks in mitosis...
April 23, 2018: Developmental Cell
Takeo Kishimoto
In metazoans that undergo sexual reproduction, genomic inheritance is ensured by two distinct types of cell cycle, mitosis and meiosis. Mitosis maintains the genomic ploidy in somatic cells reproducing within a generation, whereas meiosis reduces by half the ploidy in germ cells to prepare for successive generations. The meiotic cell cycle is believed to be a derived form of the mitotic cell cycle; however, the molecular mechanisms underlying both of these processes remain elusive. My laboratory has long studied the meiotic cell cycle in starfish oocytes, particularly the control of meiotic M-phase by maturation- or M phase-promoting factor (MPF) and the kinase cyclin B-associated Cdk1 (cyclin B-Cdk1)...
2018: Proceedings of the Japan Academy. Series B, Physical and Biological Sciences
Yang Cui, Hailong Yan, Ke Wang, Han Xu, Xuelian Zhang, Haijing Zhu, Jinwang Liu, Lei Qu, Xianyong Lan, Chuanying Pan
A previous whole-genome association analysis identified lysine demethylase 6A ( KDM6A ), which encodes a type of histone demethylase, as a candidate gene associated to goat fecundity. KDM6A gene knockout mouse disrupts gametophyte development, suggesting that it has a critical role in reproduction. In this study, goat KDM6A mRNA expression profiles were determined, insertion/deletion (indel) variants in the gene identified, indel variants effect on KDM6A gene expression assessed, and their association with first-born litter size analyzed in 2326 healthy female Shaanbei white cashmere goats...
2018: Frontiers in Genetics
Yoshie A Fujioka, Asuka Onuma, Wataru Fujii, Koji Sugiura, Kunihiko Naito
Vertebrate oocytes arrested at the first meiotic prophase must proceed to the second meiotic metaphase (MII) before fertilization. This meiotic process requires the precise control of protein degradation. Part of the protein degradation in oocytes is controlled by members of the ubiquitin-conjugating enzyme family, UBE2C and UBE2S, which are known to participate in mono-ubiquitination and poly-ubiquitination, respectively. Although UBE2 enzymes have been well studied in mitosis, their contribution to mammalian oocyte meiosis is relatively unknown and has been studied only in mice...
March 23, 2018: Journal of Reproduction and Development
Dal-Hoe Koo, William T Molin, Christopher A Saski, Jiming Jiang, Karthik Putta, Mithila Jugulam, Bernd Friebe, Bikram S Gill
Gene amplification has been observed in many bacteria and eukaryotes as a response to various selective pressures, such as antibiotics, cytotoxic drugs, pesticides, herbicides, and other stressful environmental conditions. An increase in gene copy number is often found as extrachromosomal elements that usually contain autonomously replicating extrachromosomal circular DNA molecules (eccDNAs). Amaranthus palmeri , a crop weed, can develop herbicide resistance to glyphosate [ N -(phosphonomethyl) glycine] by amplification of the 5-enolpyruvylshikimate-3-phosphate synthase ( EPSPS ) gene, the molecular target of glyphosate...
March 12, 2018: Proceedings of the National Academy of Sciences of the United States of America
Arunika Das, Jeffry Cesario, Anna Maria Hinman, Janet K Jang, Kim S McKim
Bipolar spindle assembly occurs in the absence of centrosomes in the oocytes of most organisms. In the absence of centrosomes in Drosophila oocytes, we have proposed that the kinesin 6 Subito, a MKLP-2 homolog, is required for establishing spindle bipolarity and chromosome biorientation by assembling a robust central spindle during prometaphase I. Although the functions of the conserved motor domains of kinesins is well studied, less is known about the contribution of the poorly conserved N- and C- terminal domains to motor function...
May 4, 2018: G3: Genes—Genomes—Genetics
Michael D Griswold, Cathryn Hogarth
The first step in established spermatogenesis is the production of progenitor cells by the stem cell population. The progenitor cells (undifferentiated A spermatogonia) expand in number via the formation of syncytial chains by mitosis. The mechanism by which these progenitor cells commit to meiosis and spermatogenesis is tightly controlled and results in complex morphological organization all of which is designed to efficiently achieve large numbers of spermatozoa. The major extrinsic factor that triggers the commitment to meiosis and establishes the structural complexity is retinoic acid (RA)...
March 2018: Stem Cell Research
Heike Loeser, Simon Schallenberg, Moritz von Winterfeld, Lars Tharun, Hakan Alakus, Arnulf Hölscher, Elfriede Bollschweiler, Reinhard Buettner, Thomas Zander, Alexander Quaas
Background: Esophageal adenocarcinomas show an increasing incidence in the Western world and their overall survival remains low. Microtubules are multifunctional cytoskeletal proteins involved in crucial cellular roles, including maintenance of cell shape, intracellular transport, meiosis, and mitosis. Microtubulus-TUBB3 was found overexpressed in several carcinomas suggesting a significant role in cancer development. High levels of TUBB3 expression were also described to be associated with poor clinical outcome in various cancers...
December 29, 2017: Oncotarget
Yu Ren, Feiyang Diao, Sunita Katari, Svetlana Yatsenko, Huaiyang Jiang, Michelle A Wood-Trageser, Aleksandar Rajkovic
BACKGROUND: Hypergonadotropic hypogonadism (HH) is a genetically heterogeneous disorder that usually presents with amenorrhea, atrophic ovaries, and low estrogen. Most cases of HH are idiopathic and nonsyndromic. Nucleoporin 107 (NUP107), a protein involved in transport between cytoplasm and nucleus with putative roles in meiosis/mitosis progression, was recently implicated as a cause of HH. We identified a NUP107 genetic variant in a nonconsanguineous family with two sisters affected with primary amenorrhea and HH, and generated a mouse model that carried the human variant...
March 2018: Molecular Genetics & Genomic Medicine
Lijuan Feng, Zhen Shi, Jing Xie, Binbin Ma, Xin Chen
Tissue homeostasis depends on the ability of tissue-specific adult stem cells to maintain a balance between proliferation and differentiation, as well as ensure DNA damage repair. Here, we use the Drosophila male germline stem cell system to study how a chromatin factor, enhancer of polycomb [E(Pc)], regulates the proliferation-to-differentiation (mitosis-to-meiosis) transition and DNA damage repair. We identified two critical targets of E(Pc). First, E(Pc) represses CycB transcription, likely through modulating H4 acetylation...
January 23, 2018: Cell Death and Differentiation
Xing Duan, Yu Zhang, Kun-Lin Chen, Hao-Lin Zhang, Lan-Lan Wu, Hong-Lin Liu, Zhen-Bo Wang, Shao-Chen Sun
LIM kinases (LIMK1/2) are LIM domain-containing serine/threonine/tyrosine kinases that mediate multiple cellular processes in mitosis. In the present study, we explored the functional roles and potential signaling pathway of LIMK1/2 during mouse oocyte meiosis. Disruption of LIMK1/2 activity and expression significantly decreased oocyte polar body extrusion. Live-cell imaging revealed that spindle migration was disturbed after both LIMK1 and LIMK2 knock down, and this might be due to aberrant distribution of actin filaments in the oocyte cytoplasm and cortex...
January 10, 2018: Journal of Cellular Physiology
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