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Bernstein LR, Mackenzie ACL, Chaffin CL, Lee SJ, Kraemer DC, Merchenthaler I. Gonadotropin elevation is ootoxic to ovulatory oocytes and inhibits oocyte maturation, and activin decoy receptor ActRIIB:Fc therapeutically restores maturation. Reprod Biol Endocrinol 2024; 22:52. [PMID: 38711160 PMCID: PMC11071334 DOI: 10.1186/s12958-024-01224-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Accepted: 05/01/2024] [Indexed: 05/08/2024] Open
Abstract
BACKGROUND Elevated FSH often occurs in women of advanced maternal age (AMA, age ≥ 35) and in infertility patients undergoing controlled ovarian stimulation (COS). There is controversy on whether high endogenous FSH contributes to infertility and whether high exogenous FSH adversely impacts patient pregnancy rates. METHODS The senescence-accelerated mouse-prone-8 (SAMP8) model of female reproductive aging was employed to assess the separate impacts of age and high FSH activity on the percentages (%) of viable and mature ovulated oocytes recovered after gonadotropin treatment. Young and midlife mice were treated with the FSH analog equine chorionic gonadotropin (eCG) to model both endogenous FSH elevation and exogenous FSH elevation. Previously we showed the activin inhibitor ActRIIB:Fc increases oocyte quality by preventing chromosome and spindle misalignments. Therefore, ActRIIB:Fc treatment was performed in an effort to increase % oocyte viability and % oocyte maturation. RESULTS The high FSH activity of eCG is ootoxic to ovulatory oocytes, with greater decreases in % viable oocytes in midlife than young mice. High FSH activity of eCG potently inhibits oocyte maturation, decreasing the % of mature oocytes to similar degrees in young and midlife mice. ActRIIB:Fc treatment does not prevent eCG ootoxicity, but it restores most oocyte maturation impeded by eCG. CONCLUSIONS FSH ootoxicity to ovulatory oocytes and FSH maturation inhibition pose a paradox given the well-known pro-growth and pro-maturation activities of FSH in the earlier stages of oocyte growth. We propose the FOOT Hypothesis ("FSH OoToxicity Hypothesis), that FSH ootoxicity to ovulatory oocytes comprises a new driver of infertility and low pregnancy success rates in DOR women attempting spontaneous pregnancy and in COS/IUI patients, especially AMA women. We speculate that endogenous FSH elevation also contributes to reduced fecundity in these DOR and COS/IUI patients. Restoration of oocyte maturation by ActRIB:Fc suggests that activin suppresses oocyte maturation in vivo. This contrasts with prior studies showing activin A promotes oocyte maturation in vitro. Improved oocyte maturation with agents that decrease endogenous activin activity with high specificity may have therapeutic benefit for COS/IVF patients, COS/IUI patients, and DOR patients attempting spontaneous pregnancies.
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Affiliation(s)
- Lori R Bernstein
- Pregmama, LLC, Gaithersburg, MD, 20886, USA.
- Department of Cell Biology and Genetics, Texas A & M School of Medicine, College Station, TX, 77843, USA.
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
- Department of Veterinary Integrative Biosciences, Texas A&M School of Veterinary Medicine, College Station, TX, 77843, USA.
| | - Amelia C L Mackenzie
- Department of Cell Biology and Genetics, Texas A & M School of Medicine, College Station, TX, 77843, USA
- FHI 360, Durham, NC, 27701, USA
| | - Charles L Chaffin
- Obstetrics, Gynecology & Reproductive Sciences, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Se-Jin Lee
- University of Connecticut School of Medicine, Farmington, CT, 06030, USA
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, 06030, USA
| | - Duane C Kraemer
- Department of Veterinary Physiology and Pharmacology, Texas A & M School of Veterinary Medicine, College Station, TX, 77843, USA
| | - Istvan Merchenthaler
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
- Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
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2
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He J, Zhu Q, Han P, Zhou T, Li J, Wang X, Cheng J. Transcriptomic Networks Reveal the Tissue-Specific Cold Shock Responses in Japanese Flounder ( Paralichthys olivaceus). BIOLOGY 2023; 12:784. [PMID: 37372069 DOI: 10.3390/biology12060784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2023] [Revised: 05/16/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023]
Abstract
Low temperature is among the important factors affecting the distribution, survival, growth, and physiology of aquatic animals. In this study, coordinated transcriptomic responses to 10 °C acute cold stress were investigated in the gills, hearts, livers, and spleens of Japanese flounder (Paralichthys olivaceus), an important aquaculture species in east Asia. Histological examination suggested different levels of injury among P. olivaceus tissues after cold shock, mainly in the gills and livers. Based on transcriptome and weighted gene coexpression network analysis, 10 tissue-specific cold responsive modules (CRMs) were identified, revealing a cascade of cellular responses to cold stress. Specifically, five upregulated CRMs were enriched with induced differentially expressed genes (DEGs), mainly corresponding to the functions of "extracellular matrix", "cytoskeleton", and "oxidoreductase activity", indicating the induced cellular response to cold shock. The "cell cycle/division" and "DNA complex" functions were enriched in the downregulated CRMs for all four tissues, which comprised inhibited DEGs, suggesting that even with tissue-specific responses, cold shock may induce severely disrupted cellular functions in all tissues, reducing aquaculture productivity. Therefore, our results revealed the tissue-specific regulation of the cellular response to low-temperature stress, which warrants further investigation and provides more comprehensive insights for the conservation and cultivation of P. olivaceus in cold water.
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Affiliation(s)
- Jiayi He
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, 5 Yushan Road, Qingdao 266003, China
| | - Qing Zhu
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, 5 Yushan Road, Qingdao 266003, China
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Oceanographic Institution, Ocean University of China, Sanya 572024, China
| | - Ping Han
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, 5 Yushan Road, Qingdao 266003, China
| | - Tianyu Zhou
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Oceanographic Institution, Ocean University of China, Sanya 572024, China
| | - Juyan Li
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, 5 Yushan Road, Qingdao 266003, China
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Oceanographic Institution, Ocean University of China, Sanya 572024, China
| | - Xubo Wang
- Key Laboratory of Aquacultural Biotechnology (Ningbo University), Ministry of Education, 169 Qixingnan Road, Ningbo 315832, China
| | - Jie Cheng
- Key Laboratory of Marine Genetics and Breeding (Ocean University of China), Ministry of Education, 5 Yushan Road, Qingdao 266003, China
- Key Laboratory of Tropical Aquatic Germplasm of Hainan Province, Sanya Oceanographic Institution, Ocean University of China, Sanya 572024, China
- Laboratory for Marine Fisheries Science and Food Production Processes, National Laboratory for Marine Science and Technology (Qingdao), 1 Wenhai Road, Qingdao 266237, China
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Cavin-Meza G, Mullen TJ, Czajkowski ER, Wolff ID, Divekar NS, Finkle JD, Wignall SM. ZYG-9ch-TOG promotes the stability of acentrosomal poles via regulation of spindle microtubules in C. elegans oocyte meiosis. PLoS Genet 2022; 18:e1010489. [PMID: 36449516 PMCID: PMC9757581 DOI: 10.1371/journal.pgen.1010489] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/16/2022] [Accepted: 10/21/2022] [Indexed: 12/03/2022] Open
Abstract
During mitosis, centrosomes serve as microtubule organizing centers that guide the formation of a bipolar spindle. However, oocytes of many species lack centrosomes; how meiotic spindles establish and maintain these acentrosomal poles remains poorly understood. Here, we show that the microtubule polymerase ZYG-9ch-TOG is required to maintain acentrosomal pole integrity in C. elegans oocyte meiosis. We exploited the auxin inducible degradation system to remove ZYG-9 from pre-formed spindles within minutes; this caused the poles to split apart and an unstable multipolar structure to form. Depletion of TAC-1, a protein known to interact with ZYG-9 in mitosis, caused loss of proper ZYG-9 localization and similar spindle phenotypes, further demonstrating that ZYG-9 is required for pole integrity. However, depletion of ZYG-9 or TAC-1 surprisingly did not affect the assembly or stability of monopolar spindles, suggesting that these proteins are not required for acentrosomal pole structure per se. Moreover, fluorescence recovery after photobleaching (FRAP) revealed that ZYG-9 turns over rapidly at acentrosomal poles, displaying similar turnover dynamics to tubulin itself, suggesting that ZYG-9 does not play a static structural role at poles. Together, these data support a global role for ZYG-9 in regulating the stability of bipolar spindles and demonstrate that the maintenance of acentrosomal poles requires factors beyond those acting to organize the pole structure itself.
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Affiliation(s)
- Gabriel Cavin-Meza
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Timothy J. Mullen
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Emily R. Czajkowski
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Ian D. Wolff
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Nikita S. Divekar
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Justin D. Finkle
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
| | - Sarah M. Wignall
- Department of Molecular Biosciences, Northwestern University, Evanston, Illinois, United States of America
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Barisic M, Rajendraprasad G. Mitotic poleward flux: Finding balance between microtubule dynamics and sliding. Bioessays 2021; 43:e2100079. [PMID: 34085708 DOI: 10.1002/bies.202100079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 05/13/2021] [Accepted: 05/21/2021] [Indexed: 12/13/2022]
Abstract
Continuous poleward motion of microtubules in metazoan mitotic spindles has been fascinating generations of cell biologists over the last several decades. In human cells, this so-called poleward flux was recently shown to be driven by the coordinated action of four mitotic kinesins. The sliding activities of kinesin-5/EG5 and kinesin-12/KIF15 are sequentially supported by kinesin-7/CENP-E at kinetochores and kinesin-4/KIF4A on chromosome arms, with the individual contributions peaking during prometaphase and metaphase, respectively. Although recent data elucidate the molecular mechanism underlying this cellular phenomenon, the functional roles of microtubule poleward flux during cell division remain largely elusive. Here, we discuss potential contribution of microtubule flux engine to various essential processes at different stages of mitosis.
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Affiliation(s)
- Marin Barisic
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Copenhagen, Denmark.,Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Girish Rajendraprasad
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Copenhagen, Denmark
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Barisic M, Rajendraprasad G, Steblyanko Y. The metaphase spindle at steady state - Mechanism and functions of microtubule poleward flux. Semin Cell Dev Biol 2021; 117:99-117. [PMID: 34053864 DOI: 10.1016/j.semcdb.2021.05.016] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 05/13/2021] [Accepted: 05/13/2021] [Indexed: 11/24/2022]
Abstract
The mitotic spindle is a bipolar cellular structure, built from tubulin polymers, called microtubules, and interacting proteins. This macromolecular machine orchestrates chromosome segregation, thereby ensuring accurate distribution of genetic material into the two daughter cells during cell division. Powered by GTP hydrolysis upon tubulin polymerization, the microtubule ends exhibit a metastable behavior known as the dynamic instability, during which they stochastically switch between the growth and shrinkage phases. In the context of the mitotic spindle, dynamic instability is furthermore regulated by microtubule-associated proteins and motor proteins, which enables the spindle to undergo profound changes during mitosis. This highly dynamic behavior is essential for chromosome capture and congression in prometaphase, as well as for chromosome alignment to the spindle equator in metaphase and their segregation in anaphase. In this review we focus on the mechanisms underlying microtubule dynamics and sliding and their importance for the maintenance of shape, structure and dynamics of the metaphase spindle. We discuss how these spindle properties are related to the phenomenon of microtubule poleward flux, highlighting its highly cooperative molecular basis and role in keeping the metaphase spindle at a steady state.
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Affiliation(s)
- Marin Barisic
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark; Department of Cellular and Molecular Medicine, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
| | - Girish Rajendraprasad
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark
| | - Yulia Steblyanko
- Cell Division and Cytoskeleton, Danish Cancer Society Research Center (DCRC), Strandboulevarden 49, 2100 Copenhagen, Denmark
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Zhou CJ, Wang DH, Kong XW, Han Z, Hao X, Wang XY, Wen X, Liang CG. Protein regulator of cytokinesis 1 regulates chromosome dynamics and cytoplasmic division during mouse oocyte meiotic maturation and early embryonic development. FEBS J 2021; 287:5130-5147. [PMID: 32562308 DOI: 10.1111/febs.15458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 06/01/2020] [Accepted: 06/15/2020] [Indexed: 11/28/2022]
Abstract
In contrast to the homeokinesis of mitosis, asymmetric division of cytoplasm is the conspicuous feature of meiosis in mammalian oocytes. Protein regulator of cytokinesis 1 (PRC1) is an important regulator during mitotic spindle assembly and cytoplasmic division, but its functions in oocyte meiosis and early embryo development have not been fully elucidated. In this study, we detected PRC1 expression and localization and revealed a nuclear, spindle midzone-related dynamic pattern throughout meiotic and mitotic progressions. Treatment of oocytes with the reagents taxol or nocodazole disturbed the distribution of PRC1 in metaphase II oocytes. Further, PRC1 depletion led to failure of first polar body (PB1) extrusion and spindle migration, aneuploidy and defective kinetochore-microtubule attachment and spindle assembly. Overexpression of PRC1 resulted in PB1 extrusion failure, aneuploidy and serious defects of spindle assembly. To investigate PRC1 function in early embryos, we injected Prc1 morpholino into zygotes and 2-cell stage embryos. Depletion of PRC1 in zygotes impaired 4-cell, morula and blastocyst formation. Loss of PRC1 in single or double blastomeres in 2-cell stage embryos significantly impaired cell division, indicating its indispensable role in early embryo development. Co-immunoprecipitation showed that PRC1 interacts with polo-like kinase 1 (PLK1), and functional knockdown and rescue experiments demonstrated that PRC1 recruits PLK1 to the spindle midzone to regulate cytoplasmic division during meiosis. Finally, kinesin family member 4 knockdown downregulates PRC1 expression and leads to PRC1 localization failure. Taken together, our data suggest PRC1 plays an important role during oocyte maturation and early embryonic development by regulating chromosome dynamics and cytoplasmic division.
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Affiliation(s)
- Cheng-Jie Zhou
- State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, School of Life Science, Inner Mongolia University, Hohhot, China
| | - Dong-Hui Wang
- State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, School of Life Science, Inner Mongolia University, Hohhot, China.,Chengdu Research Base of Giant Panda Breeding, Sichuan Key Laboratory of Conservation Biology for Endangered Wildlife, Sichuan Academy of Giant Panda, Chengdu, Sichuan Province, China
| | - Xiang-Wei Kong
- State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, School of Life Science, Inner Mongolia University, Hohhot, China
| | - Zhe Han
- State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, School of Life Science, Inner Mongolia University, Hohhot, China
| | - Xin Hao
- State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, School of Life Science, Inner Mongolia University, Hohhot, China
| | - Xing-Yue Wang
- State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, School of Life Science, Inner Mongolia University, Hohhot, China
| | - Xin Wen
- State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, School of Life Science, Inner Mongolia University, Hohhot, China
| | - Cheng-Guang Liang
- State Key Laboratory of Reproductive Regulation & Breeding of Grassland Livestock, School of Life Science, Inner Mongolia University, Hohhot, China
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Wang J, Veronezi GMB, Kang Y, Zagoskin M, O'Toole ET, Davis RE. Comprehensive Chromosome End Remodeling during Programmed DNA Elimination. Curr Biol 2020; 30:3397-3413.e4. [PMID: 32679104 PMCID: PMC7484210 DOI: 10.1016/j.cub.2020.06.058] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 06/09/2020] [Accepted: 06/16/2020] [Indexed: 01/14/2023]
Abstract
Germline and somatic genomes are in general the same in a multicellular organism. However, programmed DNA elimination leads to a reduced somatic genome compared to germline cells. Previous work on the parasitic nematode Ascaris demonstrated that programmed DNA elimination encompasses high-fidelity chromosomal breaks and loss of specific genome sequences including a major tandem repeat of 120 bp and ~1,000 germline-expressed genes. However, the precise chromosomal locations of these repeats, breaks regions, and eliminated genes remained unknown. We used PacBio long-read sequencing and chromosome conformation capture (Hi-C) to obtain fully assembled chromosomes of Ascaris germline and somatic genomes, enabling a complete chromosomal view of DNA elimination. We found that all 24 germline chromosomes undergo comprehensive chromosome end remodeling with DNA breaks in their subtelomeric regions and loss of distal sequences including the telomeres at both chromosome ends. All new Ascaris somatic chromosome ends are recapped by de novo telomere healing. We provide an ultrastructural analysis of Ascaris DNA elimination and show that eliminated DNA is incorporated into double membrane-bound structures, similar to micronuclei, during telophase of a DNA elimination mitosis. These micronuclei undergo dynamic changes including loss of active histone marks and localize to the cytoplasm following daughter nuclei formation and cytokinesis where they form autophagosomes. Comparative analysis of nematode chromosomes suggests that chromosome fusions occurred, forming Ascaris sex chromosomes that become independent chromosomes following DNA elimination breaks in somatic cells. These studies provide the first chromosomal view and define novel features and functions of metazoan programmed DNA elimination.
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Affiliation(s)
- Jianbin Wang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA; Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA.
| | - Giovana M B Veronezi
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Yuanyuan Kang
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Maxim Zagoskin
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA
| | - Eileen T O'Toole
- Molecular, Cellular and Developmental Biology, University of Colorado at Boulder, Boulder, CO 80309, USA
| | - Richard E Davis
- Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO 80045, USA; RNA Bioscience Initiative, University of Colorado School of Medicine, Aurora, CO 80045, USA.
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Nampt-mediated spindle sizing secures a post-anaphase increase in spindle speed required for extreme asymmetry. Nat Commun 2020; 11:3393. [PMID: 32636388 PMCID: PMC7341875 DOI: 10.1038/s41467-020-17088-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 06/09/2020] [Indexed: 12/21/2022] Open
Abstract
Meiotic divisions in oocytes are extremely asymmetric and require pre- and post-anaphase-onset phases of spindle migration. The latter induces membrane protrusion that is moulded around the spindle thereby reducing cytoplasmic loss. Here, we find that depleting the NAD biosynthetic enzyme, nicotinamide phosphoribosyl-transferase (Nampt), in mouse oocytes results in markedly longer spindles and compromises asymmetry. By analysing spindle speed in live oocytes, we identify a striking and transient acceleration after anaphase-onset that is severely blunted following Nampt-depletion. Slow-moving midzones of elongated spindles induce cortical furrowing deep within the oocyte before protrusions can form, altogether resulting in larger oocyte fragments being cleaved off. Additionally, we find that Nampt-depletion lowers NAD and ATP levels and that reducing NAD using small molecule Nampt inhibitors also compromises asymmetry. These data show that rapid midzone displacement is critical for extreme asymmetry by delaying furrowing to enable protrusions to form and link metabolic status to asymmetric division. Meiotic cell division in oocytes is asymmetric and requires microtubule spindle migration after anaphase-onset. Here, the authors show that Nampt, an enzyme of the Nicotinamide adenine dinucleotide (NAD) biosynthetic pathway, contributes to post-anaphase spindle migration and oocyte division asymmetry by controlling spindle length.
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Totsuka T, Ohsugi M. Production of mouse androgenetic embryos using spindle perturbation. Sci Rep 2020; 10:6556. [PMID: 32300113 PMCID: PMC7162913 DOI: 10.1038/s41598-020-63010-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 03/23/2020] [Indexed: 11/09/2022] Open
Abstract
To study the functional differences between maternal and paternal genomes in mammalian development, embryos with only one parental genome are often used. Androgenetic embryos are produced by the removal of maternal chromosomes before or after fertilization by techniques that require specialized skills and are associated with high risk of cellular damage. Here, we developed a novel method for producing androgenetic mouse embryos without the invasive enucleation process. We found that during in vitro fertilization in the presence of low-dose nocodazole, a microtubule destabilizing drug, whole oocyte chromosomes were extruded into the second polar body resulting in the production of androgenetic embryos. We further demonstrated that low-dose nocodazole decreased the spindle size and prevented chromosome segregation but did not compromise oocyte meiotic resumption. This led to the formation of a protrusion around the chromosomes, accumulation of protein regulator of cytokinesis 1 (PRC1) to the microtubules around the chromosomes, and assembly of a contractile ring at the neck region of the protrusion. Our method uses the intrinsic cytokinetic mechanism to exclude maternal chromatin from zygotes and may be applicable to other mammals.
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Affiliation(s)
- Takaya Totsuka
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan.,Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902, Japan
| | - Miho Ohsugi
- Department of Biological Sciences, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan. .,Department of Life Sciences, Graduate School of Arts and Sciences, The University of Tokyo, Komaba 3-8-1, Meguro-ku, Tokyo, 153-8902, Japan.
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