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Salinas-Saavedra M. SABER-FISH in Hydractinia. Methods Mol Biol 2024; 2784:77-85. [PMID: 38502479 DOI: 10.1007/978-1-0716-3766-1_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
In situ hybridization allows the detection of nucleic acid sequences in fixed cells and tissues. The gelatinous nature of cnidarians and Hydractinia demands extensive and exhausting protocols to detect RNA transcripts with traditional methods (e.g., colorimetric in situ hybridization). Signal amplification by exchange reaction (SABER) fluorescence in situ hybridization (FISH) enables simplifying and multiplex imaging of RNA targets in a rapid and cost-effective manner. In one enzymatic reaction, SABER-FISH uses a strand-displacing polymerase and catalytic DNA hairpin to generate FISH probes with adjustable signal amplification, allowing highly sensitive detection of nucleic acids and reducing the number of required probes. Here I describe the methodology to detect transcripts within the cells of Hydractinia by SABER-FISH in whole-mount samples.
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Limatola N, Chun JT, Chiba K, Santella L. Dithiothreitol Affects the Fertilization Response in Immature and Maturing Starfish Oocytes. Biomolecules 2023; 13:1659. [PMID: 38002342 PMCID: PMC10669828 DOI: 10.3390/biom13111659] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Revised: 11/14/2023] [Accepted: 11/15/2023] [Indexed: 11/26/2023] Open
Abstract
Immature starfish oocytes isolated from the ovary are susceptible to polyspermy due to the structural organization of the vitelline layer covering the oocyte plasma membrane, as well as the distribution and biochemical properties of the actin cytoskeleton of the oocyte cortex. After the resumption of the meiotic cycle of the oocyte triggered by the hormone 1-methyladenine, the maturing oocyte reaches fertilizable conditions to be stimulated by only one sperm with a normal Ca2+ response and cortical reaction. This cytoplasmic ripening of the oocyte, resulting in normal fertilization and development, is due to the remodeling of the cortical actin cytoskeleton and germinal vesicle breakdown (GVBD). Since disulfide-reducing agents such as dithiothreitol (DTT) are known to induce the maturation and GVBD of oocytes in many species of starfish, we analyzed the pattern of the fertilization response displayed by Astropecten aranciacus oocytes pre-exposed to DTT with or without 1-MA stimulation. Short treatment of A. aranciacus immature oocytes with DTT reduced the rate of polyspermic fertilization and altered the sperm-induced Ca2+ response by changing the morphology of microvilli, cortical granules, and biochemical properties of the cortical F-actin. At variance with 1-MA, the DTT treatment of immature starfish oocytes for 70 min did not induce GVBD. On the other hand, the DTT treatment caused an alteration in microvilli morphology and a drastic depolymerization of the cortical F-actin, which impaired the sperm-induced Ca2+ response at fertilization and the subsequent embryonic development.
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Affiliation(s)
- Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy;
| | - Kazuyoshi Chiba
- Department of Biological Sciences, Ochanomizu University, Tokyo 112-8610, Japan;
| | - Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
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Del Llano E, Iyyappan R, Aleshkina D, Masek T, Dvoran M, Jiang Z, Pospisek M, Kubelka M, Susor A. SGK1 is essential for meiotic resumption in mammalian oocytes. Eur J Cell Biol 2022; 101:151210. [PMID: 35240557 PMCID: PMC11008056 DOI: 10.1016/j.ejcb.2022.151210] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/21/2022] [Accepted: 02/22/2022] [Indexed: 01/09/2023] Open
Abstract
In mammalian females, oocytes are stored in the ovary and meiosis is arrested at the diplotene stage of prophase I. When females reach puberty oocytes are selectively recruited in cycles to grow, overcome the meiotic arrest, complete the first meiotic division and become mature (ready for fertilization). At a molecular level, the master regulator of prophase I arrest and meiotic resumption is the maturation-promoting factor (MPF) complex, formed by the active form of cyclin dependent kinase 1 (CDK1) and Cyclin B1. However, we still do not have complete information regarding the factors implicated in MPF activation. In this study we document that out of three mammalian serum-glucocorticoid kinase proteins (SGK1, SGK2, SGK3), mouse oocytes express only SGK1 with a phosphorylated (active) form dominantly localized in the nucleoplasm. Further, suppression of SGK1 activity in oocytes results in decreased CDK1 activation via the phosphatase cell division cycle 25B (CDC25B), consequently delaying or inhibiting nuclear envelope breakdown. Expression of exogenous constitutively active CDK1 can rescue the phenotype induced by SGK1 inhibition. These findings bring new insights into the molecular pathways acting upstream of MPF and a better understanding of meiotic resumption control by presenting a new key player SGK1 in mammalian oocytes.
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Affiliation(s)
- Edgar Del Llano
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, CAS, Libechov, Czech Republic.
| | - Rajan Iyyappan
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, CAS, Libechov, Czech Republic
| | - Daria Aleshkina
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, CAS, Libechov, Czech Republic
| | - Tomas Masek
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, Prague 128 44, Czech Republic
| | - Michal Dvoran
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, CAS, Libechov, Czech Republic
| | - Zongliang Jiang
- School of Animal Sciences, AgCenter, Louisiana State University, Baton Rouge, LA 70803, United States
| | - Martin Pospisek
- Laboratory of RNA Biochemistry, Department of Genetics and Microbiology, Faculty of Science, Charles University, Viničná 5, Prague 128 44, Czech Republic
| | - Michal Kubelka
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, CAS, Libechov, Czech Republic
| | - Andrej Susor
- Laboratory of Biochemistry and Molecular Biology of Germ Cells, Institute of Animal Physiology and Genetics, CAS, Libechov, Czech Republic.
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Hosoda E, Chiba K. Fluorescence Measurement and Calibration of Intracellular pH in Starfish Oocytes. Bio Protoc 2020; 10:e3778. [PMID: 33659434 DOI: 10.21769/bioprotoc.3778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 07/27/2020] [Accepted: 08/17/2020] [Indexed: 11/02/2022] Open
Abstract
Oocyte maturation is a process wherein an oocyte arrested at prophase of meiosis I resumes meiosis to become a fertilizable egg. In starfish ovaries, a hormone released from follicle cells activates the oocytes, resulting in an increase in their intracellular pH (pHi), which is required for spindle assembly. Herein, we describe a protocol for pHi measurement in living oocytes microinjected with the pH-sensitive dye BCECF. For in vivo BCECF calibration, we treated oocytes with artificial seawater containing CH3COONH4 to clamp pHi, injected pH-standard solutions, and converted the BCECF fluorescence intensity ratios to pHi values. Of note, if the actual pHi is higher or lower than the known pH of injected standard solutions, the BCECF fluorescence intensity ratio will decrease or increase, respectively. On the other hand, the pH of the injected solution displaying no change in fluorescence intensity should be considered the actual pHi. These methods for pHi calibration and clamping are simple and reproducible.
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Affiliation(s)
- Enako Hosoda
- Department of Biological Sciences, Ochanomizu University, Tokyo, Japan
| | - Kazuyoshi Chiba
- Department of Biological Sciences, Ochanomizu University, Tokyo, Japan
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Jessus C, Munro C, Houliston E. Managing the Oocyte Meiotic Arrest-Lessons from Frogs and Jellyfish. Cells 2020; 9:E1150. [PMID: 32392797 PMCID: PMC7290932 DOI: 10.3390/cells9051150] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/03/2020] [Accepted: 05/05/2020] [Indexed: 12/11/2022] Open
Abstract
During oocyte development, meiosis arrests in prophase of the first division for a remarkably prolonged period firstly during oocyte growth, and then when awaiting the appropriate hormonal signals for egg release. This prophase arrest is finally unlocked when locally produced maturation initiation hormones (MIHs) trigger entry into M-phase. Here, we assess the current knowledge of the successive cellular and molecular mechanisms responsible for keeping meiotic progression on hold. We focus on two model organisms, the amphibian Xenopus laevis, and the hydrozoan jellyfish Clytia hemisphaerica. Conserved mechanisms govern the initial meiotic programme of the oocyte prior to oocyte growth and also, much later, the onset of mitotic divisions, via activation of two key kinase systems: Cdk1-Cyclin B/Gwl (MPF) for M-phase activation and Mos-MAPkinase to orchestrate polar body formation and cytostatic (CSF) arrest. In contrast, maintenance of the prophase state of the fully-grown oocyte is assured by highly specific mechanisms, reflecting enormous variation between species in MIHs, MIH receptors and their immediate downstream signalling response. Convergence of multiple signalling pathway components to promote MPF activation in some oocytes, including Xenopus, is likely a heritage of the complex evolutionary history of spawning regulation, but also helps ensure a robust and reliable mechanism for gamete production.
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Affiliation(s)
- Catherine Jessus
- Laboratoire de Biologie du Développement - Institut de Biologie Paris Seine, LBD - IBPS, Sorbonne Université, CNRS, F-75005 Paris, France
| | - Catriona Munro
- Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France;
- Inserm, Center for Interdisciplinary Research in Biology, Collège de France, PSL Research University, CNRS, 75005 Paris, France
| | - Evelyn Houliston
- Laboratoire de Biologie du Développement de Villefranche-sur-mer (LBDV), Sorbonne Université, CNRS, 06230 Villefranche-sur-mer, France;
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Abstract
Oocyte maturation is a process that occurs in the ovaries, where an immature oocyte resumes meiosis to attain competence for normal fertilization after ovulation/spawning. In starfish, the hormone 1-methyladenine binds to an unidentified receptor on the plasma membrane of oocytes, inducing a conformational change in the heterotrimeric GTP-binding protein α-subunit (Gα), so that the α-subunit binds GTP in exchange of GDP on the plasma membrane. The GTP-binding protein βγ-subunit (Gβγ) is released from Gα, and the released Gβγ activates phosphatidylinositol-3 kinase (PI3K), followed by the target of rapamycin kinase complex2 (TORC2) and 3-phosphoinositide-dependent protein kinase 1 (PDK1)-dependent phosphorylation of serum- and glucocorticoid-regulated kinase (SGK) of ovarian oocytes. Thereafter, SGK activates Na+/H+ exchanger (NHE) to increase the intracellular pH (pHi) from ~6.7 to ~6.9. Moreover, SGK phosphorylates Cdc25 and Myt1, thereby inducing the de-phosphorylation and activation of cyclin B–Cdk1, causing germinal vesicle breakdown (GVBD). Both pHi increase and GVBD are required for spindle assembly at metaphase I, followed by MI arrest at pHi 6.9 until spawning. Due to MI arrest or SGK-dependent pHi control, spawned oocytes can be fertilized normally
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Affiliation(s)
- Kazuyoshi Chiba
- Department of Biological Sciences, Ochanomizu University, Tokyo 112-8610, Japan
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Hiraoka D, Hosoda E, Chiba K, Kishimoto T. SGK phosphorylates Cdc25 and Myt1 to trigger cyclin B-Cdk1 activation at the meiotic G2/M transition. J Cell Biol 2019; 218:3597-3611. [PMID: 31537708 PMCID: PMC6829662 DOI: 10.1083/jcb.201812122] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Revised: 06/03/2019] [Accepted: 07/26/2019] [Indexed: 02/06/2023] Open
Abstract
The kinase cyclin B-Cdk1 complex is a master regulator of M-phase in both mitosis and meiosis. At the G2/M transition, cyclin B-Cdk1 activation is initiated by a trigger that reverses the balance of activities between Cdc25 and Wee1/Myt1 and is further accelerated by autoregulatory loops. In somatic cell mitosis, this trigger was recently proposed to be the cyclin A-Cdk1/Plk1 axis. However, in the oocyte meiotic G2/M transition, in which hormonal stimuli induce cyclin B-Cdk1 activation, cyclin A-Cdk1 is nonessential and hence the trigger remains elusive. Here, we show that SGK directly phosphorylates Cdc25 and Myt1 to trigger cyclin B-Cdk1 activation in starfish oocytes. Upon hormonal stimulation of the meiotic G2/M transition, SGK is activated by cooperation between the Gβγ-PI3K pathway and an unidentified pathway downstream of Gβγ, called the atypical Gβγ pathway. These findings identify the trigger in oocyte meiosis and provide insights into the role and activation of SGK.
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Affiliation(s)
- Daisaku Hiraoka
- Science and Education Center, Ochanomizu University, Tokyo, Japan
| | - Enako Hosoda
- Department of Biological Sciences, Ochanomizu University, Tokyo, Japan
| | - Kazuyoshi Chiba
- Department of Biological Sciences, Ochanomizu University, Tokyo, Japan
| | - Takeo Kishimoto
- Science and Education Center, Ochanomizu University, Tokyo, Japan
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