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Turner KA, Achinger L, Kong D, Kluczynski DF, Fishman EL, Phillips A, Saltzman B, Loncarek J, Harstine BR, Avidor-Reiss T. Abnormal centriolar biomarker ratios correlate with unexplained bull artificial insemination subfertility: a pilot study. Sci Rep 2023; 13:18338. [PMID: 37884598 PMCID: PMC10603076 DOI: 10.1038/s41598-023-45162-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 10/17/2023] [Indexed: 10/28/2023] Open
Abstract
The mechanisms underlying male infertility are poorly understood. Most mammalian spermatozoa have two centrioles: the typical barrel-shaped proximal centriole (PC) and the atypical fan-like distal centriole (DC) connected to the axoneme (Ax). These structures are essential for fertility. However, the relationship between centriole quality and subfertility (reduced fertility) is not well established. Here, we tested the hypothesis that assessing sperm centriole quality can identify cattle subfertility. By comparing sperm from 25 fertile and 6 subfertile bulls, all with normal semen analyses, we found that unexplained subfertility and lower sire conception rates (pregnancy rate from artificial insemination in cattle) correlate with abnormal centriolar biomarker distribution. Fluorescence-based Ratiometric Analysis of Sperm Centrioles (FRAC) found only four fertile bulls (4/25, 16%) had positive FRAC tests (having one or more mean FRAC ratios outside of the distribution range in a group's high-quality sperm population), whereas all of the subfertile bulls (6/6, 100%) had positive FRAC tests (P = 0.00008). The most sensitive biomarker was acetylated tubulin, which had a novel labeling pattern between the DC and Ax. These data suggest that FRAC and acetylated tubulin labeling can identify bull subfertility that remains undetected by current methods and may provide insight into a novel mechanism of subfertility.
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Affiliation(s)
- Katerina A Turner
- Department of Biological Sciences, College of Natural Sciences and Mathematics, University of Toledo, 3050 W. Towerview Blvd, Toledo, OH, 43606, USA
| | - Luke Achinger
- Department of Biological Sciences, College of Natural Sciences and Mathematics, University of Toledo, 3050 W. Towerview Blvd, Toledo, OH, 43606, USA
| | - Dong Kong
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Institutes of Health, National Cancer Institute, Frederick, MD, USA
| | - Derek F Kluczynski
- Department of Biological Sciences, College of Natural Sciences and Mathematics, University of Toledo, 3050 W. Towerview Blvd, Toledo, OH, 43606, USA
| | - Emily Lillian Fishman
- Department of Biological Sciences, College of Natural Sciences and Mathematics, University of Toledo, 3050 W. Towerview Blvd, Toledo, OH, 43606, USA
| | - Audrey Phillips
- Department of Biological Sciences, College of Natural Sciences and Mathematics, University of Toledo, 3050 W. Towerview Blvd, Toledo, OH, 43606, USA
| | - Barbara Saltzman
- Department of Population Health, College of Health and Human Services, University of Toledo, Toledo, OH, USA
| | - Jadranka Loncarek
- Laboratory of Protein Dynamics and Signaling, Center for Cancer Research, National Institutes of Health, National Cancer Institute, Frederick, MD, USA
| | | | - Tomer Avidor-Reiss
- Department of Biological Sciences, College of Natural Sciences and Mathematics, University of Toledo, 3050 W. Towerview Blvd, Toledo, OH, 43606, USA.
- Department of Urology, College of Medicine and Life Sciences, University of Toledo, Toledo, OH, USA.
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2
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Zhong L, Shu HB. Mitotic inactivation of the cGAS‒MITA/STING pathways. J Mol Cell Biol 2021; 13:721-727. [PMID: 34609492 PMCID: PMC8718187 DOI: 10.1093/jmcb/mjab061] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Revised: 08/12/2021] [Accepted: 08/23/2021] [Indexed: 11/13/2022] Open
Abstract
The cyclic guanosine monophosphate‒adenosine monophosphate synthase (cGAS)‒mediator of interferon response factor 3 activation/stimulator of interferon genes (MITA/STING) axis has emerged as a major pathway, which senses microbial or mislocated cellular DNA in the cytosol to trigger innate immune responses. cGAS senses cytosolic DNA without a preference of self- or nonself-DNA. How the cGAS‒MITA/STING axis is inactivated upon nuclear envelope breakdown (NEBD) at mitotic entry in vertebrate cells to avoid self-DNA sensing remains unclear until very recently. In this review, we summarize the recent advances on how cGAS responds to chromosomes upon NEBD and the mechanisms involved in the inactivation of the cGAS‒MITA/STING pathways in mitosis.
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Affiliation(s)
- Li Zhong
- Department of Infectious Diseases, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Research Unit of Innate Immune and Inflammatory Diseases of the Chinese Academy of Medical Sciences, Wuhan 430071, China
| | - Hong-Bing Shu
- Department of Infectious Diseases, Frontier Science Center for Immunology and Metabolism, Medical Research Institute, Zhongnan Hospital of Wuhan University, Wuhan University, Research Unit of Innate Immune and Inflammatory Diseases of the Chinese Academy of Medical Sciences, Wuhan 430071, China
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3
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Swartz SZ, Nguyen HT, McEwan BC, Adamo ME, Cheeseman IM, Kettenbach AN. Selective dephosphorylation by PP2A-B55 directs the meiosis I-meiosis II transition in oocytes. eLife 2021; 10:70588. [PMID: 34342579 PMCID: PMC8370769 DOI: 10.7554/elife.70588] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2021] [Accepted: 08/02/2021] [Indexed: 12/17/2022] Open
Abstract
Meiosis is a specialized cell cycle that requires sequential changes to the cell division machinery to facilitate changing functions. To define the mechanisms that enable the oocyte-to-embryo transition, we performed time-course proteomics in synchronized sea star oocytes from prophase I through the first embryonic cleavage. Although we found that protein levels were broadly stable, our analysis reveals that dynamic waves of phosphorylation underlie each meiotic stage. We found that the phosphatase PP2A-B55 is reactivated at the meiosis I/meiosis II (MI/MII) transition, resulting in the preferential dephosphorylation of threonine residues. Selective dephosphorylation is critical for directing the MI/MII transition as altering PP2A-B55 substrate preferences disrupts key cell cycle events after MI. In addition, threonine to serine substitution of a conserved phosphorylation site in the substrate INCENP prevents its relocalization at anaphase I. Thus, through its inherent phospho-threonine preference, PP2A-B55 imposes specific phosphoregulated behaviors that distinguish the two meiotic divisions.
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Affiliation(s)
- S Zachary Swartz
- Whitehead Institute for Biomedical Research, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Hieu T Nguyen
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Brennan C McEwan
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, United States
| | - Mark E Adamo
- Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, United States
| | - Iain M Cheeseman
- Whitehead Institute for Biomedical Research, Cambridge, United States.,Department of Biology, Massachusetts Institute of Technology, Cambridge, United States
| | - Arminja N Kettenbach
- Department of Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth, Hanover, United States.,Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, United States
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4
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Iwao Y, Kimoto C, Fujimoto A, Suda A, Hara Y. Physiological polyspermy: Selection of a sperm nucleus for the development of diploid genomes in amphibians. Mol Reprod Dev 2020; 87:358-369. [DOI: 10.1002/mrd.23235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Accepted: 06/23/2019] [Indexed: 01/04/2023]
Affiliation(s)
- Yasuhiro Iwao
- Laboratory of Reproductive Developmental Biology, Division of Earth Sciences, Biology, and Chemistry, Graduate School of Sciences and Technology for InnovationYamaguchi University Yamaguchi Yamaguchi Japan
| | - Chihiro Kimoto
- Laboratory of Reproductive Developmental Biology, Division of Earth Sciences, Biology, and Chemistry, Graduate School of Sciences and Technology for InnovationYamaguchi University Yamaguchi Yamaguchi Japan
| | - Ayaka Fujimoto
- Laboratory of Reproductive Developmental Biology, Division of Earth Sciences, Biology, and Chemistry, Graduate School of Sciences and Technology for InnovationYamaguchi University Yamaguchi Yamaguchi Japan
| | - Asuka Suda
- Laboratory of Reproductive Developmental Biology, Division of Earth Sciences, Biology, and Chemistry, Graduate School of Sciences and Technology for InnovationYamaguchi University Yamaguchi Yamaguchi Japan
| | - Yuki Hara
- Laboratory of Evolutionary Cell Biology, Department of Biology and Chemistry, Faculty of ScienceYamaguchi University Yamaguchi Yamaguchi Japan
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5
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Goto T, Kanda K, Nishikata T. Non-centrosomal microtubule structures regulated by egg activation signaling contribute to cytoplasmic and cortical reorganization in the ascidian egg. Dev Biol 2018; 448:161-172. [PMID: 31030741 DOI: 10.1016/j.ydbio.2018.10.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 10/10/2018] [Accepted: 10/17/2018] [Indexed: 10/28/2022]
Abstract
In the first ascidian cell cycle, cytoplasmic and cortical reorganization is required for distributing maternal factors to their appropriate positions, resulting in the formation of the embryonic axis. This cytoplasmic reorganization is considered to depend on the cortical microfilament network in the first phase and on the sperm astral microtubule (MT) in the second phase. Recently, we described three novel MT structures: a deeply extended MT meshwork (DEM) in the entire subcortical region of the unfertilized egg, transiently accumulated MT fragments (TAF) in the vegetal pole, and a cortical MT array in the posterior vegetal cortex (CAMP). Particularly, our previous study showed CAMP to contribute to the movement of myoplasm. In addition, it is very similar to the parallel MT array, which appears during cortical rotation in Xenopus eggs. However, how these MT structures are organized is still unclear. Here, we investigated the relationship between the egg activation pathway and MT structures during the first ascidian cell cycle. First, we carefully analyzed cell cycle progression through meiosis I and II and the first mitosis, and successfully established a standard time table of cell cycle events. Using this time table as a reference, we precisely described the behavior of novel MT structures and revealed that it was closely correlated with cell cycle events. Moreover, pharmacological experiments supported the relationship between these MT structures and the signal transduction mechanisms that begin after fertilization, including Ca2+ signaling, MPF signaling, and MEK/MAPK signaling. Especially, CAMP formation was directed by activities of cyclin-dependent kinases. As these MT structures are conserved, at least, within chordate group, we emphasize the importance of understanding the controlling mechanisms of MT dynamics, which is important for embryonic axis determination in the ascidian egg.
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Affiliation(s)
- Toshiyuki Goto
- Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Hyogo 650-0047, Japan
| | - Kazumasa Kanda
- Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Hyogo 650-0047, Japan
| | - Takahito Nishikata
- Frontiers of Innovative Research in Science and Technology (FIRST), Konan University, Kobe, Hyogo 650-0047, Japan.
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6
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Takatori N, Oonuma K, Nishida H, Saiga H. Polarization of PI3K Activity Initiated by Ooplasmic Segregation Guides Nuclear Migration in the Mesendoderm. Dev Cell 2016; 35:333-43. [PMID: 26555053 DOI: 10.1016/j.devcel.2015.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Revised: 09/16/2015] [Accepted: 10/15/2015] [Indexed: 11/29/2022]
Abstract
Asymmetric localization of RNA is a widely observed mechanism of cell polarization. Using embryos of the ascidian, Halocynthia roretzi, we previously showed that mesoderm and endoderm fates are separated by localization of mRNA encoding a transcription factor, Not, to the future mesoderm-side cytoplasm of the mesendoderm cell through asymmetric positioning of the nucleus. Here, we investigated the mechanism that defines the direction of the nuclear migration. We show that localization of PtdIns(3,4,5)P3 to the future mesoderm region determines the direction of nuclear migration. Localization of PtdIns(3,4,5)P3 was dependent on the localization of PI3Kα to the future mesoderm region. PI3Kα was first localized at the 1-cell stage by the ooplasmic movement. Activity of localized PI3Kα at the 4-cell stage was required for the localization of PI3Kα up to the nuclear migration. Our results provide the scaffold for understanding the chain of causality leading to the separation of germ layer fates.
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Affiliation(s)
- Naohito Takatori
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiohsawa, Hachioji, Tokyo 192-0397, Japan; Department of Biological Sciences, Graduate school of Science, Osaka University 1-1, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
| | - Kouhei Oonuma
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiohsawa, Hachioji, Tokyo 192-0397, Japan
| | - Hiroki Nishida
- Department of Biological Sciences, Graduate school of Science, Osaka University 1-1, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Hidetoshi Saiga
- Department of Biological Sciences, Graduate School of Science and Engineering, Tokyo Metropolitan University, 1-1 Minamiohsawa, Hachioji, Tokyo 192-0397, Japan
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7
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Ohnishi Y, Hoshino R, Okamoto T. Dynamics of Male and Female Chromatin during Karyogamy in Rice Zygotes. PLANT PHYSIOLOGY 2014; 165:1533-1543. [PMID: 24948834 PMCID: PMC4119036 DOI: 10.1104/pp.114.236059] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 06/14/2014] [Indexed: 05/20/2023]
Abstract
In angiosperms, the conversion of an egg cell into a zygote involves two sequential gametic processes: plasmogamy, the fusion of the plasma membranes of male and female gametes, and karyogamy, the fusion of the gametic nuclei. In this study, the nuclei and nuclear membranes of rice (Oryza sativa) gametes were fluorescently labeled using histones 2B-green fluorescent protein/red fluorescent protein and Sad1/UNC-84-domain protein2-green fluorescent protein, respectively, which were heterologously expressed. These gametes were fused in vitro to produce zygotes, and the nuclei and nuclear membranes in the zygotes were observed during karyogamy. The results indicated that the sperm nucleus migrates adjacent to the egg nucleus 5 to 10 min after plasmogamy via an actin cytoskelton, and the egg chromatin then appears to move unidirectionally into the sperm nucleus through a possible nuclear connection. The enlargement of the sperm nucleus accompanies this possible chromatin remodeling. Then, 30 to 70 min after fusion, the sperm chromatin begins to decondense with the completion of karyogamy. Based on these observations, the development of early rice zygotes from plasmogamy to karyogamy was divided into eight stages, and using reverse transcription PCR analyses, paternal and de novo synthesized transcripts were separately detected in zygotes at early and late karyogamy stages, respectively.
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Affiliation(s)
- Yukinosuke Ohnishi
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Rina Hoshino
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
| | - Takashi Okamoto
- Department of Biological Sciences, Tokyo Metropolitan University, Tokyo 192-0397, Japan
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8
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Abstract
The cell-cycle regulators that control meiotic divisions also regulate the events that accompany the oocyte-to-zygote transition. Thus, the meiotic machinery functions as an internal pacemaker that propels the oocyte toward embryogenesis. The preimplantation embryo expresses a number of receptors that are important for initial activity of the phosphatidylinositol 3-kinase-protein kinase B (PI3K-Akt/PKB) pathway. The complete PI3K-Akt/PKB-CDK1 cascade is implicated as a key regulator of a number of cellular functions. Selective inhibition of protein kinase B (Akt/PKB) with inhibitor SH6 and cyclin-dependent kinase 1 (CDK1) with inhibitor roscovitine arrest development of the 1-cell preimplantation mouse embryo before entry into the first mitosis. The pronuclei of these inhibited embryos migrate to one another, but do not progress to pronuclei envelope breakdown and pronuclear fusion running immediately before the onset of mitosis. SH6-treated 1-cell mouse embryos showed a high occurrence of apoptosis features (nuclear fragmentation, positive terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL), active caspase-3 in both cytoplasm and nucleoplasm). In the Akt/PKB-inhibited embryos, the active phosphorylated form Ser473Akt/PKB was not detected in pronuclear areas when compared with inhibitor-free controls. Although CDK1-inhibited 1-cell embryos also failed to enter into the first mitosis, the presence of apoptotic cell death features was not observed. In the roscovitine-treated embryos, Ser473Akt/PKB was detected in the pronuclei independently of CDK1 activity. We conclude that Akt/PKB plays an important role during entry of the 1-cell mouse embryo into the first mitosis, and probably functions as a relay in the cell-cycle stage. We assume that Akt/PKB is the primary target responsible for mediating anti-apoptotic signals in the 1-cell mouse embryo.
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9
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Bower DV, Sato Y, Lansford R. Dynamic lineage analysis of embryonic morphogenesis using transgenic quail and 4D multispectral imaging. Genesis 2011; 49:619-43. [PMID: 21509927 DOI: 10.1002/dvg.20754] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2010] [Revised: 03/27/2011] [Accepted: 03/28/2011] [Indexed: 12/17/2022]
Abstract
We describe the development of transgenic quail that express various fluorescent proteins in targeted manners and their use as a model system that integrates advanced imaging approaches with conventional and emerging molecular genetics technologies. We also review the progression and complications of past fate mapping techniques that led us to generate transgenic quail, which permit dynamic imaging of amniote embryogenesis with unprecedented subcellular resolution.
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Affiliation(s)
- Danielle V Bower
- Department of Biology and the Biological Imaging Center, California Institute of Technology, Pasadena, California 91125, USA
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10
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Hu X, Moscinski LC. Cdc2: a monopotent or pluripotent CDK? Cell Prolif 2011; 44:205-11. [PMID: 21535261 PMCID: PMC6496858 DOI: 10.1111/j.1365-2184.2011.00753.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 12/12/2010] [Indexed: 01/20/2023] Open
Abstract
Cell cycle progression is controlled by both extracellular and intracellular signalling molecules. It has been generally believed that cdc2/CDK1 only control G(2)-M transition in mammalian and many other higher eukaryotic cells. Accumulating evidence shows that cdc2 not only promotes G(2)-M transition but is also capable of regulating G(1) progress and G(1)-S transition via association with multiple interphase cyclins; cdc2 activity can be inhibited by p21 and p27, two traditional G(1) CDK inhibitors. In addition, cdc2-cyclin B controls pronuclear union in interphase fertilized eggs. These data suggest that cdc2 may be a pluripotent CDK. Although mechanisms responsible for the multiple functions of cdc2 remain to be further investigated, interactions of cdc2 with pRb and with several important transcription factors may provide a clue to the pluripotent role of cdc2.
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Affiliation(s)
- X Hu
- Department of Biology, College of Arts & Sciences, Barry University, Miami Shores, FL, USA.
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11
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Abe Y, Okumura E, Hosoya T, Hirota T, Kishimoto T. A single starfish Aurora kinase performs the combined functions of Aurora-A and Aurora-B in human cells. J Cell Sci 2010; 123:3978-88. [DOI: 10.1242/jcs.076315] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aurora, an essential mitotic kinase, is highly conserved during evolution. Most vertebrates have at least two Aurora kinases, Aurora-A and Aurora-B, which have distinct functions in the centrosome–spindle and inner centromere–midbody, respectively. However, some non-vertebrate deuterostomes have only a single Aurora. It remains to be verified whether the single Aurora performs the same functions as vertebrate Auroras A and B combined. We have isolated a cDNA of a single Aurora (ApAurora) from the echinoderm starfish, Asterina pectinifera, and show that ApAurora displays most features of both Aurora-A and Aurora-B in starfish oocytes and early embryos. Furthermore, ApAurora that is stably expressed in HeLa cells can substitute for both human Aurora-A and Aurora-B when either is reduced by RNAi. A single ApAurora thus has properties of both Aurora-A and Aurora-B in starfish eggs and HeLa cells. Together with phylogenetic analysis indicating that ApAurora forms a clade with all types of vertebrate Auroras and single Auroras of non-vertebrate deuterostomes, our observations support the idea that the single Aurora found in non-vertebrate deuterostomes represents the ancestor that gave rise to various types of vertebrate Auroras. This study thus provides functional evidence for phylogenetic considerations.
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Affiliation(s)
- Yusuke Abe
- Laboratory of Cell and Developmental Biology, Graduate School of Bioscience, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Eiichi Okumura
- Laboratory of Cell and Developmental Biology, Graduate School of Bioscience, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Takamitsu Hosoya
- Department of Biological Information, Graduate School of Bioscience, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
| | - Toru Hirota
- Department of Experimental Pathology, Cancer Institute of the Japanese Foundation for Cancer Research, Koto-ku, Tokyo 135-8550, Japan
| | - Takeo Kishimoto
- Laboratory of Cell and Developmental Biology, Graduate School of Bioscience, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8501, Japan
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12
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Chudakov DM, Matz MV, Lukyanov S, Lukyanov KA. Fluorescent proteins and their applications in imaging living cells and tissues. Physiol Rev 2010; 90:1103-63. [PMID: 20664080 DOI: 10.1152/physrev.00038.2009] [Citation(s) in RCA: 925] [Impact Index Per Article: 66.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Green fluorescent protein (GFP) from the jellyfish Aequorea victoria and its homologs from diverse marine animals are widely used as universal genetically encoded fluorescent labels. Many laboratories have focused their efforts on identification and development of fluorescent proteins with novel characteristics and enhanced properties, resulting in a powerful toolkit for visualization of structural organization and dynamic processes in living cells and organisms. The diversity of currently available fluorescent proteins covers nearly the entire visible spectrum, providing numerous alternative possibilities for multicolor labeling and studies of protein interactions. Photoactivatable fluorescent proteins enable tracking of photolabeled molecules and cells in space and time and can also be used for super-resolution imaging. Genetically encoded sensors make it possible to monitor the activity of enzymes and the concentrations of various analytes. Fast-maturing fluorescent proteins, cell clocks, and timers further expand the options for real time studies in living tissues. Here we focus on the structure, evolution, and function of GFP-like proteins and their numerous applications for in vivo imaging, with particular attention to recent techniques.
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13
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Initiation of DNA replication after fertilization is regulated by p90Rsk at pre-RC/pre-IC transition in starfish eggs. Proc Natl Acad Sci U S A 2010; 107:5006-11. [PMID: 20185755 DOI: 10.1073/pnas.1000587107] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Initiation of DNA replication in eukaryotic cells is controlled through an ordered assembly of protein complexes at replication origins. The molecules involved in this process are well conserved but diversely regulated. Typically, initiation of DNA replication is regulated in response to developmental events in multicellular organisms. Here, we elucidate the regulation of the first S phase of the embryonic cell cycle after fertilization. Unless fertilization occurs, the Mos-MAPK-p90Rsk pathway causes the G1-phase arrest after completion of meiosis in starfish eggs. Fertilization shuts down this pathway, leading to the first S phase with no requirement of new protein synthesis. However, how and in which stage the initiation complex for DNA replication is arrested by p90Rsk remains unclear. We find that in G1-arrested eggs, chromatin is loaded with the Mcm complex to form the prereplicative complex (pre-RC). Inactivation of p90Rsk is necessary and sufficient for further loading of Cdc45 onto chromatin to form the preinitiation complex (pre-IC) and the subsequent initiation of DNA replication. However, cyclin A-, B-, and E-Cdk's activity and Cdc7 accumulation are dispensable for these processes. These observations define the stage of G1 arrest in unfertilized eggs at transition point from pre-RC to pre-IC, and reveal a unique role of p90Rsk for a negative regulator of this transition. Thus, initiation of DNA replication in the meiosis-to-mitosis transition is regulated at the pre-RC stage as like in the G1 checkpoint, but in a manner different from the checkpoint.
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14
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Kisielewska J, Philipova R, Huang JY, Whitaker M. MAP kinase dependent cyclinE/cdk2 activity promotes DNA replication in early sea urchin embryos. Dev Biol 2009; 334:383-94. [PMID: 19665013 PMCID: PMC2789238 DOI: 10.1016/j.ydbio.2009.07.043] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Revised: 06/30/2009] [Accepted: 07/27/2009] [Indexed: 12/23/2022]
Abstract
Sea urchins provide an excellent model for studying cell cycle control mechanisms governing DNA replication in vivo. Fertilization and cell cycle progression are tightly coordinated by Ca(2+) signals, but the mechanisms underlying the onset of DNA replication after fertilization remain less clear. In this study we demonstrate that calcium-dependent activation of ERK1 promotes accumulation of cyclinE/cdk2 into the male and female pronucleus and entry into first S-phase. We show that cdk2 activity rises quickly after fertilization to a maximum at 4 min, corresponding in timing to the early ERK1 activity peak. Abolishing MAP kinase activity after fertilization with MEK inhibitor, U0126, substantially reduces the early peak of cdk2 activity and prevents cyclinE and cdk2 accumulation in both sperm pronucleus and zygote nucleus in vivo. Both p27(kip1) and roscovitine, cdk2 inhibitors, prevented DNA replication suggesting cdk2 involvement in this process in sea urchin. Inhibition of cdk2 activity using p27(kip1) had no effect on the phosphorylation of MBP by ERK, but completely abolished phosphorylation of retinoblastoma protein, a cdk2 substrate, indicating that cdk2 activity is downstream of ERK1 activation. This pattern of regulation of DNA synthesis conforms to the pattern observed in mammalian somatic cells.
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Affiliation(s)
| | | | | | - M. Whitaker
- The Institute for Cell and Molecular Biosciences, Medical School, Faculty of Medical Sciences, Newcastle University, Framlington Place, NE2 4HH, Newcastle upon Tyne, UK
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15
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Hara M, Mori M, Wada T, Tachibana K, Kishimoto T. Start of the embryonic cell cycle is dually locked in unfertilized starfish eggs. Development 2009; 136:1687-96. [PMID: 19369392 DOI: 10.1242/dev.035261] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A key event in the oocyte-to-embryo transition is the start of the embryonic mitotic cell cycle. Prior to this start, the cell cycle in oocytes is generally arrested at a particular stage during meiosis, and the meiotic arrest is released by fertilization. However, it remains unclear how release from the meiotic arrest is implicated in the start of the embryonic cell cycle. To elucidate this link, we have used starfish eggs, in which G1 phase arrest occurs after completion of meiosis if the mature oocytes are not fertilized, and fertilization simply directs the start of the embryonic cell cycle. The starfish G1 arrest is known to rely on the Mos-MAPK-Rsk (p90 ribosomal S6 kinase) pathway, and inactivation of Rsk induces S phase in the absence of fertilization. However, here we show that this S phase is not followed by M phase when MAPK remains active, owing to poly(A)-independent repression of cyclin A and B synthesis. By contrast, inactivation of MAPK alone induces M phase, even when S phase is inhibited by constitutively active Rsk. Thus, there is a divergence of separate pathways downstream of MAPK that together block the start of the embryonic mitotic cycle. One is the previously known Rsk-dependent pathway that prevents S phase, and the other is a novel pathway that is not mediated by Rsk and that leads to prevention of the first mitotic M phase through suppression of protein synthesis of M phase cyclins. Release from such a 'dual-lock' by fertilization results in the start of the embryonic cell cycle.
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Affiliation(s)
- Masatoshi Hara
- Graduate School of BioscienceTokyo Institute of Technology, Nagatsuta, Midoriku, Yokohama 226-8501, Japan
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