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Mangini M, Limatola N, Ferrara MA, Coppola G, Chun JT, De Luca AC, Santella L. Application of Raman spectroscopy to the evaluation of F-actin changes in sea urchin eggs at fertilization. ZYGOTE 2024; 32:38-48. [PMID: 38050697 DOI: 10.1017/s0967199423000552] [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: 12/06/2023]
Abstract
The actin filaments on the surface of echinoderm oocytes and eggs readily undergo massive reorganization during meiotic maturation and fertilization. In sea urchin eggs, the actin cytoskeletal response to the fertilizing sperm is fast enough to accompany Ca2+ signals and to guide sperm's entry into the egg. Although recent work using live cell imaging technology confirmed changes in the actin polymerization status in fertilized eggs, as was previously shown using light and electron microscopy, it failed to provide experimental evidence of F-actin depolymerization a few seconds after insemination, which is concurrent with the sperm-induced Ca2+ release. In the present study, we applied Raman microspectroscopy to tackle this issue by examining the spectral profiles of the egg's subplasmalemmal regions before and after treating the eggs with actin drugs or fertilizing sperm. At both early (15 s) and late (15 min) time points after fertilization, specific peak shifts in the Raman spectra revealed change in the actin structure, and Raman imaging detected the cytoskeletal changes corresponding to the F-actin reorganization visualized with LifeAct-GFP in confocal microscopy. Our observation suggests that the application of Raman spectroscopy, which does not require microinjection of fluorescent probes and exogenous gene expression, may serve as an alternative or even advantageous method in disclosing rapid subtle changes in the subplasmalemmal actin cytoskeleton that are difficult to resolve.
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Affiliation(s)
- Maria Mangini
- Institute of Experimental Endocrinology and Oncology 'G. Salvatore', Second Unit, National Research Council, 80131Naples, Italy
| | - Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121Naples, Italy
| | - Maria Antonietta Ferrara
- Institute of Applied Sciences and Intelligent Systems 'E. Caianiello', Unit of Naples, National Research Council, 80131Naples, Italy
| | - Giuseppe Coppola
- Institute of Applied Sciences and Intelligent Systems 'E. Caianiello', Unit of Naples, National Research Council, 80131Naples, Italy
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121Naples, Italy
| | - Anna Chiara De Luca
- Institute of Experimental Endocrinology and Oncology 'G. Salvatore', Second Unit, National Research Council, 80131Naples, Italy
| | - Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121Naples, Italy
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The Therapeutic and Diagnostic Potential of Phospholipase C Zeta, Oocyte Activation, and Calcium in Treating Human Infertility. Pharmaceuticals (Basel) 2023; 16:ph16030441. [PMID: 36986540 PMCID: PMC10056371 DOI: 10.3390/ph16030441] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 02/19/2023] [Accepted: 03/06/2023] [Indexed: 03/17/2023] Open
Abstract
Oocyte activation, a fundamental event during mammalian fertilisation, is initiated by concerted intracellular patterns of calcium (Ca2+) release, termed Ca2+ oscillations, predominantly driven by testis-specific phospholipase C zeta (PLCζ). Ca2+ exerts a pivotal role in not just regulating oocyte activation and driving fertilisation, but also in influencing the quality of embryogenesis. In humans, a failure of Ca2+ release, or defects in related mechanisms, have been reported to result in infertility. Furthermore, mutations in the PLCζ gene and abnormalities in sperm PLCζ protein and RNA, have been strongly associated with forms of male infertility where oocyte activation is deficient. Concurrently, specific patterns and profiles of PLCζ in human sperm have been linked to parameters of semen quality, suggesting the potential for PLCζ as a powerful target for both therapeutics and diagnostics of human fertility. However, further to PLCζ and given the strong role played by Ca2+ in fertilisation, targets down- and up-stream of this process may also present a significantly similar level of promise. Herein, we systematically summarise recent advancements and controversies in the field to update expanding clinical associations between Ca2+-release, PLCζ, oocyte activation and human fertility. We discuss how such associations may potentially underlie defective embryogenesis and recurrent implantation failure following fertility treatments, alongside potential diagnostic and therapeutic avenues presented by oocyte activation for the diagnosis and treatment of human infertility.
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The Effect of Acidic and Alkaline Seawater on the F-Actin-Dependent Ca 2+ Signals Following Insemination of Immature Starfish Oocytes and Mature Eggs. Cells 2023; 12:cells12050740. [PMID: 36899875 PMCID: PMC10000582 DOI: 10.3390/cells12050740] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Revised: 02/07/2023] [Accepted: 02/23/2023] [Indexed: 03/03/2023] Open
Abstract
In starfish, the addition of the hormone 1-methyladenine (1-MA) to immature oocytes (germinal vesicle, GV-stage) arrested at the prophase of the first meiotic division induces meiosis resumption (maturation), which makes the mature eggs able to respond to the sperm with a normal fertilization response. The optimal fertilizability achieved during the maturation process results from the exquisite structural reorganization of the actin cytoskeleton in the cortex and cytoplasm induced by the maturing hormone. In this report, we have investigated the influence of acidic and alkaline seawater on the structure of the cortical F-actin network of immature oocytes of the starfish (Astropecten aranciacus) and its dynamic changes upon insemination. The results have shown that the altered seawater pH strongly affected the sperm-induced Ca2+ response and the polyspermy rate. When immature starfish oocytes were stimulated with 1-MA in acidic or alkaline seawater, the maturation process displayed a strong dependency on pH in terms of the dynamic structural changes of the cortical F-actin. The resulting alteration of the actin cytoskeleton, in turn, affected the pattern of Ca2+ signals at fertilization and sperm penetration.
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Santella L, Chun JT. Structural actin dynamics during oocyte maturation and fertilization. Biochem Biophys Res Commun 2022; 633:13-16. [DOI: 10.1016/j.bbrc.2022.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 09/01/2022] [Indexed: 11/06/2022]
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Limatola N, Chun JT, Santella L. Species-Specific Gamete Interaction during Sea Urchin Fertilization: Roles of the Egg Jelly and Vitelline Layer. Cells 2022; 11:cells11192984. [PMID: 36230946 PMCID: PMC9563080 DOI: 10.3390/cells11192984] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/09/2022] [Accepted: 09/21/2022] [Indexed: 11/16/2022] Open
Abstract
In sea urchins, the sequence of the cellular and molecular events characterizing the fertilization process has been intensively studied. We have learned that to activate the egg, the fertilizing sperm must undergo morphological modifications (the acrosome reaction, AR) upon reaching the outer gelatinous layer enveloping the egg (egg jelly), which triggers the polymerization of F-actin on the sperm head to form the acrosomal process. The AR exposes bindin, an adhesive sperm protein essential for the species-specific interaction with the cognate receptor on the egg vitelline layer. To investigate the specific roles of the egg jelly and vitelline layer at fertilization of sea urchin eggs, Paracentrotus lividus eggs were incubated in acidic seawater, which removes the egg jelly, i.e., experimental conditions that should prevent the occurrence of the AR, and inseminated in the same medium. At variance with the prevailing view, our results have shown that these dejellied P. lividus eggs can still interact with sperm in acidic seawater, albeit with altered fertilization responses. In particular, the eggs deprived of the vitelline layer reacted with multiple sperm but with altered Ca2+ signals. The results have provided experimental evidence that the plasma membrane, and not the vitelline layer, is where the specific recognition between gametes occurs. The vitelline layer works in unfertilized eggs to prevent polyspermy.
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Affiliation(s)
- Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
- Correspondence: (N.L.); (L.S.); Tel.: +39-081-583-3229 (N.L.); +39-081-583-3289 (L.S.)
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
| | - Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
- Correspondence: (N.L.); (L.S.); Tel.: +39-081-583-3229 (N.L.); +39-081-583-3289 (L.S.)
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Regulation of the Actin Cytoskeleton-Linked Ca2+ Signaling by Intracellular pH in Fertilized Eggs of Sea Urchin. Cells 2022; 11:cells11091496. [PMID: 35563801 PMCID: PMC9100012 DOI: 10.3390/cells11091496] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 04/19/2022] [Accepted: 04/26/2022] [Indexed: 01/27/2023] Open
Abstract
In sea urchin, the immediate contact of the acrosome-reacted sperm with the egg surface triggers a series of structural and ionic changes in the egg cortex. Within one minute after sperm fuses with the egg plasma membrane, the cell membrane potential changes with the concurrent increases in intracellular Ca2+ levels. The consequent exocytosis of the cortical granules induces separation of the vitelline layer from the egg plasma membrane. While these cortical changes are presumed to prevent the fusion of additional sperm, the subsequent late phase (between 1 and 4 min after fertilization) is characterized by reorganization of the egg cortex and microvilli (elongation) and by the metabolic shift to activate de novo protein and DNA syntheses. The latter biosynthetic events are crucial for embryonic development. Previous studies suggested that the early phase of fertilization was not a prerequisite for these changes in the second phase since the increase in the intracellular pH induced by the exposure of unfertilized sea urchin eggs to ammonia seawater could start metabolic egg activation in the absence of the cortical granule exocytosis. In the present study, we have demonstrated that the incubation of unfertilized eggs in ammonia seawater induced considerable elongations of microvilli (containing actin filaments) as a consequence of the intracellular pH increase, which increased the egg’s receptivity to sperm and made the eggs polyspermic at fertilization despite the elevation of the fertilization envelope (FE). These eggs also displayed compromised Ca2+ signals at fertilization, as the amplitude of the cortical flash was significantly reduced and the elevated intracellular Ca2+ level declined much faster. These results have also highlighted the importance of the increased internal pH in regulating Ca2+ signaling and the microvillar actin cytoskeleton during the late phase of the fertilization process.
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Liang C, Huang M, Li T, Li L, Sussman H, Dai Y, Siemann DW, Xie M, Tang X. Towards an integrative understanding of cancer mechanobiology: calcium, YAP, and microRNA under biophysical forces. SOFT MATTER 2022; 18:1112-1148. [PMID: 35089300 DOI: 10.1039/d1sm01618k] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
An increasing number of studies have demonstrated the significant roles of the interplay between microenvironmental mechanics in tissues and biochemical-genetic activities in resident tumor cells at different stages of tumor progression. Mediated by molecular mechano-sensors or -transducers, biomechanical cues in tissue microenvironments are transmitted into the tumor cells and regulate biochemical responses and gene expression through mechanotransduction processes. However, the molecular interplay between the mechanotransduction processes and intracellular biochemical signaling pathways remains elusive. This paper reviews the recent advances in understanding the crosstalk between biomechanical cues and three critical biochemical effectors during tumor progression: calcium ions (Ca2+), yes-associated protein (YAP), and microRNAs (miRNAs). We address the molecular mechanisms underpinning the interplay between the mechanotransduction pathways and each of the three effectors. Furthermore, we discuss the functional interactions among the three effectors in the context of soft matter and mechanobiology. We conclude by proposing future directions on studying the tumor mechanobiology that can employ Ca2+, YAP, and miRNAs as novel strategies for cancer mechanotheraputics. This framework has the potential to bring insights into the development of novel next-generation cancer therapies to suppress and treat tumors.
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Affiliation(s)
- Chenyu Liang
- Department of Mechanical & Aerospace Engineering, Herbert Wertheim College of Engineering (HWCOE), Gainesville, FL, 32611, USA.
- UF Health Cancer Center (UFHCC), Gainesville, FL, 32611, USA
| | - Miao Huang
- Department of Mechanical & Aerospace Engineering, Herbert Wertheim College of Engineering (HWCOE), Gainesville, FL, 32611, USA.
- UF Health Cancer Center (UFHCC), Gainesville, FL, 32611, USA
| | - Tianqi Li
- UF Health Cancer Center (UFHCC), Gainesville, FL, 32611, USA
- Department of Biochemistry and Molecular Biology, College of Medicine (COM), Gainesville, FL, 32611, USA.
| | - Lu Li
- UF Health Cancer Center (UFHCC), Gainesville, FL, 32611, USA
- Department of Biochemistry and Molecular Biology, College of Medicine (COM), Gainesville, FL, 32611, USA.
| | - Hayley Sussman
- Department of Radiation Oncology, COM, Gainesville, FL, 32611, USA
| | - Yao Dai
- UF Health Cancer Center (UFHCC), Gainesville, FL, 32611, USA
- UF Genetics Institute (UFGI), University of Florida (UF), Gainesville, FL, 32611, USA
| | - Dietmar W Siemann
- UF Health Cancer Center (UFHCC), Gainesville, FL, 32611, USA
- UF Genetics Institute (UFGI), University of Florida (UF), Gainesville, FL, 32611, USA
| | - Mingyi Xie
- UF Health Cancer Center (UFHCC), Gainesville, FL, 32611, USA
- Department of Biochemistry and Molecular Biology, College of Medicine (COM), Gainesville, FL, 32611, USA.
- Department of Biomedical Engineering, College of Engineering (COE), University of Delaware (UD), Newark, DE, 19716, USA
| | - Xin Tang
- Department of Mechanical & Aerospace Engineering, Herbert Wertheim College of Engineering (HWCOE), Gainesville, FL, 32611, USA.
- UF Health Cancer Center (UFHCC), Gainesville, FL, 32611, USA
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Kashir J, Ganesh D, Jones C, Coward K. OUP accepted manuscript. Hum Reprod Open 2022; 2022:hoac003. [PMID: 35261925 PMCID: PMC8894871 DOI: 10.1093/hropen/hoac003] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 01/16/2022] [Indexed: 11/16/2022] Open
Abstract
BACKGROUND Oocyte activation deficiency (OAD) is attributed to the majority of cases underlying failure of ICSI cycles, the standard treatment for male factor infertility. Oocyte activation encompasses a series of concerted events, triggered by sperm-specific phospholipase C zeta (PLCζ), which elicits increases in free cytoplasmic calcium (Ca2+) in spatially and temporally specific oscillations. Defects in this specific pattern of Ca2+ release are directly attributable to most cases of OAD. Ca2+ release can be clinically mediated via assisted oocyte activation (AOA), a combination of mechanical, electrical and/or chemical stimuli which artificially promote an increase in the levels of intra-cytoplasmic Ca2+. However, concerns regarding safety and efficacy underlie potential risks that must be addressed before such methods can be safely widely used. OBJECTIVE AND RATIONALE Recent advances in current AOA techniques warrant a review of the safety and efficacy of these practices, to determine the extent to which AOA may be implemented in the clinic. Importantly, the primary challenges to obtaining data on the safety and efficacy of AOA must be determined. Such questions require urgent attention before widespread clinical utilization of such protocols can be advocated. SEARCH METHODS A literature review was performed using databases including PubMed, Web of Science, Medline, etc. using AOA, OAD, calcium ionophores, ICSI, PLCζ, oocyte activation, failed fertilization and fertilization failure as keywords. Relevant articles published until June 2019 were analysed and included in the review, with an emphasis on studies assessing large-scale efficacy and safety. OUTCOMES Contradictory studies on the safety and efficacy of AOA do not yet allow for the establishment of AOA as standard practice in the clinic. Heterogeneity in study methodology, inconsistent sample inclusion criteria, non-standardized outcome assessments, restricted sample size and animal model limitations render AOA strictly experimental. The main scientific concern impeding AOA utilization in the clinic is the non-physiological method of Ca2+ release mediated by most AOA agents, coupled with a lack of holistic understanding regarding the physiological mechanism(s) underlying Ca2+ release at oocyte activation. LIMITATIONS, REASONS FOR CAUTION The number of studies with clinical relevance using AOA remains significantly low. A much wider range of studies examining outcomes using multiple AOA agents are required. WIDER IMPLICATIONS In addition to addressing the five main challenges of studies assessing AOA safety and efficacy, more standardized, large-scale, multi-centre studies of AOA, as well as long-term follow-up studies of children born from AOA, would provide evidence for establishing AOA as a treatment for infertility. The delivery of an activating agent that can more accurately recapitulate physiological fertilization, such as recombinant PLCζ, is a promising prospect for the future of AOA. Further to PLCζ, many other avenues of physiological oocyte activation also require urgent investigation to assess other potential physiological avenues of AOA. STUDY FUNDING/COMPETING INTERESTS D.G. was supported by Stanford University’s Bing Overseas Study Program. J.K. was supported by a Healthcare Research Fellowship Award (HF-14-16) made by Health and Care Research Wales (HCRW), alongside a National Science, Technology, and Innovation plan (NSTIP) project grant (15-MED4186-20) awarded by the King Abdulaziz City for Science and Technology (KACST). The authors have no competing interests to declare.
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Affiliation(s)
| | | | - Celine Jones
- Nuffield Department of Women’s & Reproductive Health, University of Oxford, Level 3, Women’s Centre, John Radcliffe Hospital, Oxford, UK
| | - Kevin Coward
- Correspondence address. Nuffield Department of Women’s & Reproductive Health, University of Oxford, Level 3, Women’s Centre, John Radcliffe Hospital, Oxford, OS3 9DU, UK. E-mail: https://orcid.org/0000-0003-3577-4041
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Limatola N, Chun JT, Cherraben S, Schmitt JL, Lehn JM, Santella L. Effects of Dithiothreitol on Fertilization and Early Development in Sea Urchin. Cells 2021; 10:3573. [PMID: 34944081 PMCID: PMC8700669 DOI: 10.3390/cells10123573] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 12/11/2021] [Accepted: 12/15/2021] [Indexed: 01/20/2023] Open
Abstract
The vitelline layer (VL) of a sea urchin egg is an intricate meshwork of glycoproteins that intimately ensheathes the plasma membrane. During fertilization, the VL plays important roles. Firstly, the receptors for sperm reside on the VL. Secondly, following cortical granule exocytosis, the VL is elevated and transformed into the fertilization envelope (FE), owing to the assembly and crosslinking of the extruded materials. As these two crucial stages involve the VL, its alteration was expected to affect the fertilization process. In the present study, we addressed this question by mildly treating the eggs with a reducing agent, dithiothreitol (DTT). A brief pretreatment with DTT resulted in partial disruption of the VL, as judged by electron microscopy and by a novel fluorescent polyamine probe that selectively labelled the VL. The DTT-pretreated eggs did not elevate the FE but were mostly monospermic at fertilization. These eggs also manifested certain anomalies at fertilization: (i) compromised Ca2+ signaling, (ii) blocked translocation of cortical actin filaments, and (iii) impaired cleavage. Some of these phenotypic changes were reversed by restoring the DTT-exposed eggs in normal seawater prior to fertilization. Our findings suggest that the FE is not the decisive factor preventing polyspermy and that the integrity of the VL is nonetheless crucial to the egg's fertilization response.
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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
| | - Sawsen Cherraben
- Laboratory of Supramolecular Chemistry, Institut de Science et d’Ingénierie Supramoléculaires ISIS—Université de Strasbourg, 8 allée Gaspard Monge, 67000 Strasbourg, France; (S.C.); (J.-L.S.); (J.-M.L.)
| | - Jean-Louis Schmitt
- Laboratory of Supramolecular Chemistry, Institut de Science et d’Ingénierie Supramoléculaires ISIS—Université de Strasbourg, 8 allée Gaspard Monge, 67000 Strasbourg, France; (S.C.); (J.-L.S.); (J.-M.L.)
| | - Jean-Marie Lehn
- Laboratory of Supramolecular Chemistry, Institut de Science et d’Ingénierie Supramoléculaires ISIS—Université de Strasbourg, 8 allée Gaspard Monge, 67000 Strasbourg, France; (S.C.); (J.-L.S.); (J.-M.L.)
| | - Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy;
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Vasilev F, Ezhova Y, Chun JT. Signaling Enzymes and Ion Channels Being Modulated by the Actin Cytoskeleton at the Plasma Membrane. Int J Mol Sci 2021; 22:ijms221910366. [PMID: 34638705 PMCID: PMC8508623 DOI: 10.3390/ijms221910366] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/23/2021] [Accepted: 09/23/2021] [Indexed: 02/06/2023] Open
Abstract
A cell should deal with the changing external environment or the neighboring cells. Inevitably, the cell surface receives and transduces a number of signals to produce apt responses. Typically, cell surface receptors are activated, and during this process, the subplasmalemmal actin cytoskeleton is often rearranged. An intriguing point is that some signaling enzymes and ion channels are physically associated with the actin cytoskeleton, raising the possibility that the subtle changes of the local actin cytoskeleton can, in turn, modulate the activities of these proteins. In this study, we reviewed the early and new experimental evidence supporting the notion of actin-regulated enzyme and ion channel activities in various cell types including the cells of immune response, neurons, oocytes, hepatocytes, and epithelial cells, with a special emphasis on the Ca2+ signaling pathway that depends on the synthesis of inositol 1,4,5-trisphosphate. Some of the features that are commonly found in diverse cells from a wide spectrum of the animal species suggest that fine-tuning of the activities of the enzymes and ion channels by the actin cytoskeleton may be an important strategy to inhibit or enhance the function of these signaling proteins.
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Affiliation(s)
- Filip Vasilev
- Centre de Recherche du Centre Hospitalier de l’Université de Montréal (CRCHUM), 900 Rue St Denis, Montreal, QC H2X 0A9, Canada
- Correspondence: (F.V.); (J.T.C.); Tel.: +1-514-249-5862 (F.V.); +39-081-583-3407 (J.T.C.)
| | - Yulia Ezhova
- Maisonneuve-Rosemont Hospital Research Centre, University of Montreal, Montreal, QC H1T 2M4, Canada;
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, 80121 Napoli, Italy
- Correspondence: (F.V.); (J.T.C.); Tel.: +1-514-249-5862 (F.V.); +39-081-583-3407 (J.T.C.)
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Limatola N, Chun JT, Santella L. Fertilization and development of Arbacia lixula eggs are affected by osmolality conditions. Biosystems 2021; 206:104448. [PMID: 34058296 DOI: 10.1016/j.biosystems.2021.104448] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Revised: 05/21/2021] [Accepted: 05/21/2021] [Indexed: 10/21/2022]
Abstract
The sea urchin Arbacia lixula coexist with Paracentrotus lividus in the Mediterranean, but the two sea urchin species are quite different from each other. Concerning the female gamete, A. lixula eggs are much darker than those of P. lividus due to the characteristic pigmentation. Upon insemination, the fertilization envelope formed by A. lixula eggs is remarkably thinner than that of P. livius eggs, which implies that the cortical organization of the eggs in the two species may be quite different. In this communication, we examined the phenotypic plasticity of A. lixula eggs in the changing osmolality. The plasma membrane, cortical actin cytoskeleton and vesicles are extensively altered in the eggs exposed to 40% seawater for 15 min. When fertilized, the Ca2+ response in these eggs was significantly compromised and the sperm often failed to enter the eggs. Remarkably, the pattern of the Ca2+ response was restored when these eggs were transferring back to the natural seawater before fertilization, while the actin cytoskeleton partially reverted to the original state. Nonetheless, these eggs restored in seawater failed to regain the innate sperm receptivity that allows only one sperm to enter in natural seawater. Thus, the ability to guide monospermic fertilization is lost by water entry into the eggs, and the eggs incorporated either multiple or no sperm. On the other hand, eggs briefly exposed to hypertonic seawater exhibited no evident morphological anomaly. Nonetheless, the monospermic eggs that experienced a brief exposure (15 min) to hypertonic seawater prior to fertilization in natural seawater displayed a subtly altered sperm-induced Ca2+ response and morpho-functional anomaly around the pluteus stage. Our results suggest that A. lixula eggs attain only a limited extent of cytological plasticity, and that the osmolality shock affects the physical nature of the egg surface which in turn affects the developmental programming.
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Affiliation(s)
- Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Napoli, Italy.
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Napoli, Italy
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Han Y, Shi W, Tang Y, Zhao X, Du X, Sun S, Zhou W, Liu G. Ocean acidification increases polyspermy of a broadcast spawning bivalve species by hampering membrane depolarization and cortical granule exocytosis. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2021; 231:105740. [PMID: 33440272 DOI: 10.1016/j.aquatox.2020.105740] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 12/27/2020] [Accepted: 12/29/2020] [Indexed: 06/12/2023]
Abstract
Ensuring that oocytes are fertilized by a single sperm during broadcast spawning is crucial for the fertilization success of many marine invertebrates. Although the adverse impacts of ocean acidification (OA) on various marine species have been revealed in recent years, its impact on polyspermy and the underlying mechanisms involved remain largely unknown. Therefore, in the present study, the effect of OA on polyspermy risk was assessed in a broadcast spawning bivalve, Tegillarca granosa. In addition, the impacts of OA on the two polyspermy blocking processes, the fast block (membrane depolarization) and the permanent block (cortical reaction), were investigated. The results show that the exposure of oocytes to two future OA scenarios (pH 7.8 and pH 7.4) leads to significant increases in polyspermy risk, about 1.70 and 2.38 times higher than the control, respectively. The maximum change in the membrane potential during oocyte membrane depolarization markedly decreased to 15.79 % (pH 7.8) and 34.06 % (pH 7.4) of the control value. Moreover, the duration of oocyte membrane depolarization was significantly reduced to approximately 63.38 % (pH 7.8) and 21.91 % (pH 7.4) of the control. In addition, cortical granule exocytosis, as well as microfilament migration, were significantly arrested by OA treatment. Exposure to future OA scenarios also led to significant reductions in the ATP and Ca2+ content of the oocytes, which may explain the hampered polyspermy blocking. Overall, the present study suggests that OA may significantly increase polyspermy risk in T. granosa by inhibiting membrane depolarization and arresting cortical granule exocytosis.
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Affiliation(s)
- Yu Han
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Wei Shi
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Yu Tang
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Xinguo Zhao
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China; Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, 266071, PR China
| | - Xueying Du
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Shuge Sun
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Weishang Zhou
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China
| | - Guangxu Liu
- College of Animal Sciences, Zhejiang University, Hangzhou, 310058, PR China.
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13
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Limatola N, Chun JT, Santella L. Effects of Salinity and pH of Seawater on the Reproduction of the Sea Urchin Paracentrotus lividus. THE BIOLOGICAL BULLETIN 2020; 239:13-23. [PMID: 32812816 DOI: 10.1086/710126] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
AbstractFertilization and early development are usually the most vulnerable stages in the life of marine animals, and the biological processes during this period are highly sensitive to the environment. In nature, sea urchin gametes are shed in seawater, where they undergo external fertilization and embryonic development. In a laboratory, it is possible to follow the exact morphological and biochemical changes taking place in the fertilized eggs and the developing embryos. Thus, observation of successful fertilization and the subsequent embryonic development of sea urchin eggs can be used as a convenient biosensor to assess the quality of the marine environment. In this paper, we have examined how salinity and pH changes affect the normal fertilization process and the following development of Paracentrotus lividus. The results of our studies using confocal microscopy, scanning and transmission electron microscopy, and time-lapse Ca2+ image recording indicated that both dilution and acidification of seawater have subtle but detrimental effects on many aspects of the fertilization process. They include Ca2+ signaling and coordinated actin cytoskeletal changes, leading to a significantly reduced rate of successful fertilization and, eventually, to abnormal or delayed embryonic development.
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14
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Santella L, Limatola N, Chun JT. Cellular and molecular aspects of oocyte maturation and fertilization: a perspective from the actin cytoskeleton. ZOOLOGICAL LETTERS 2020; 6:5. [PMID: 32313685 PMCID: PMC7158055 DOI: 10.1186/s40851-020-00157-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 03/26/2020] [Indexed: 05/06/2023]
Abstract
ABSTRACT Much of the scientific knowledge on oocyte maturation, fertilization, and embryonic development has come from the experiments using gametes of marine organisms that reproduce by external fertilization. In particular, echinoderm eggs have enabled the study of structural and biochemical changes related to meiotic maturation and fertilization owing to the abundant availability of large and transparent oocytes and eggs. Thus, in vitro studies of oocyte maturation and sperm-induced egg activation in starfish are carried out under experimental conditions that resemble those occurring in nature. During the maturation process, immature oocytes of starfish are released from the prophase of the first meiotic division, and acquire the competence to be fertilized through a highly programmed sequence of morphological and physiological changes at the oocyte surface. In addition, the changes in the cortical and nuclear regions are essential for normal and monospermic fertilization. This review summarizes the current state of research on the cortical actin cytoskeleton in mediating structural and physiological changes during oocyte maturation and sperm and egg activation in starfish and sea urchin. The common denominator in these studies with echinoderms is that exquisite rearrangements of the egg cortical actin filaments play pivotal roles in gamete interactions, Ca2+ signaling, exocytosis of cortical granules, and control of monospermic fertilization. In this review, we also compare findings from studies using invertebrate eggs with what is known about the contributions made by the actin cytoskeleton in mammalian eggs. Since the cortical actin cytoskeleton affects microvillar morphology, movement, and positioning of organelles and vesicles, and the topography of the egg surface, these changes have impacts on the fertilization process, as has been suggested by recent morphological studies on starfish oocytes and eggs using scanning electron microscopy. Drawing the parallelism between vitelline layer of echinoderm eggs and the zona pellucida of mammalian eggs, we also discuss the importance of the egg surface in mediating monospermic fertilization. GRAPHICAL ABSTRACT
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Affiliation(s)
- Luigia Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli 80121, Italy
| | - Nunzia Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli 80121, Italy
| | - Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli 80121, Italy
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15
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Kashir J. Increasing associations between defects in phospholipase C zeta and conditions of male infertility: not just ICSI failure? J Assist Reprod Genet 2020; 37:1273-1293. [PMID: 32285298 PMCID: PMC7311621 DOI: 10.1007/s10815-020-01748-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 03/12/2020] [Indexed: 12/12/2022] Open
Abstract
PURPOSE Oocyte activation is a fundamental event at mammalian fertilization. In mammals, this process is initiated by a series of characteristic calcium (Ca2+) oscillations, induced by a sperm-specific phospholipase C (PLC) termed PLCzeta (PLCζ). Dysfunction/reduction/deletion of PLCζ is associated with forms of male infertility where the sperm is unable to initiate Ca2+ oscillations and oocyte activation, specifically in cases of fertilization failure. This review article aims to systematically summarize recent advancements and controversies in the field to update expanding clinical associations between PLCζ and various male factor conditions. This article also discusses how such associations may potentially underlie defective embryogenesis and recurrent implantation failure following fertility treatments, alongside potential diagnostic and therapeutic PLCζ approaches, aiming to direct future research efforts to utilize such knowledge clinically. METHODS An extensive literature search was performed using literature databases (PubMed/MEDLINE/Web of Knowledge) focusing on phospholipase C zeta (PLCzeta; PLCζ), oocyte activation, and calcium oscillations, as well as specific male factor conditions. RESULTS AND DISCUSSION Defective PLCζ or PLCζ-induced Ca2+ release can be linked to multiple forms of male infertility including abnormal sperm parameters and morphology, sperm DNA fragmentation and oxidation, and abnormal embryogenesis/pregnancies. Such sperm exhibit absent/reduced levels, and abnormal localization patterns of PLCζ within the sperm head. CONCLUSIONS Defective PLCζ and abnormal patterns of Ca2+ release are increasingly suspected a significant causative factor underlying abnormalities or insufficiencies in Ca2+ oscillation-driven early embryogenic events. Such cases could potentially strongly benefit from relevant therapeutic and diagnostic applications of PLCζ, or even alternative mechanisms, following further focused research efforts.
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Affiliation(s)
- Junaid Kashir
- College of Medicine, Alfaisal University, Riyadh, Kingdom of Saudi Arabia. .,School of Biosciences, Cardiff University, Cardiff, UK. .,Department of Comparative Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Kingdom of Saudi Arabia.
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16
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Byrnes WM. E. E. Just's broad, yet hidden, influence on modern cell and developmental biology. Mol Reprod Dev 2020; 87:380-391. [DOI: 10.1002/mrd.23270] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 08/30/2019] [Indexed: 11/12/2022]
Affiliation(s)
- W. Malcolm Byrnes
- Department of Biochemistry and Molecular BiologyHoward University College of Medicine Washington DC
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17
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Saleh A, Kashir J, Thanassoulas A, Safieh-Garabedian B, Lai FA, Nomikos M. Essential Role of Sperm-Specific PLC-Zeta in Egg Activation and Male Factor Infertility: An Update. Front Cell Dev Biol 2020; 8:28. [PMID: 32064262 PMCID: PMC7000359 DOI: 10.3389/fcell.2020.00028] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Accepted: 01/14/2020] [Indexed: 12/16/2022] Open
Abstract
Sperm-specific phospholipase C zeta (PLCζ) is widely considered to be the physiological stimulus responsible for generating calcium (Ca2+) oscillations that induce egg activation and early embryonic development during mammalian fertilization. In the mammalian testis, PLCζ expression is detected at spermiogenesis following elongated spermatid differentiation. Sperm-delivered PLCζ induces Ca2+ release via the inositol 1,4,5-trisphosphate (InsP3) signaling pathway. PLCζ is the smallest known mammalian PLC isoform identified to date, with the simplest domain organization. However, the distinctive biochemical properties of PLCζ compared with other PLC isoforms contribute to its unique potency in stimulating cytosolic Ca2+ oscillations within mammalian eggs. Moreover, studies describing PLCζ “knockout” mouse phenotypes confirm the supreme importance of PLCζ at egg activation and monospermic fertilization in mice. Importantly, a number of clinical reports have highlighted the crucial importance of PLCζ in human fertilization by associating PLCζ deficiencies with certain forms of male factor infertility. Herein, we give an update on recent advances that have refined our understanding of how sperm PLCζ triggers Ca2 + oscillations and egg activation in mammals, while also discussing the nature of a potential “alternative” sperm factor. We summarise PLCζ localization in mammalian sperm, and the direct links observed between defective PLCζ protein in sperm and documented cases of male infertility. Finally, we postulate how this sperm protein can be used as a potential diagnostic marker, and also as a powerful therapeutic agent for treatment of certain types of male infertility due to egg activation failure or even in more general cases of male subfertility.
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Affiliation(s)
- Alaaeldin Saleh
- Member of QU Health, College of Medicine, Qatar University, Doha, Qatar
| | - Junaid Kashir
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia.,Department of Comparative Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia.,School of Biosciences, Cardiff University, Cardiff, United Kingdom
| | | | | | - F Anthony Lai
- Member of QU Health, College of Medicine, Qatar University, Doha, Qatar.,Biomedical Research Center, Qatar University, Doha, Qatar
| | - Michail Nomikos
- Member of QU Health, College of Medicine, Qatar University, Doha, Qatar
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18
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Nicotine Induces Polyspermy in Sea Urchin Eggs through a Non-Cholinergic Pathway Modulating Actin Dynamics. Cells 2019; 9:cells9010063. [PMID: 31881774 PMCID: PMC7016604 DOI: 10.3390/cells9010063] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 12/02/2019] [Accepted: 12/21/2019] [Indexed: 01/02/2023] Open
Abstract
While alkaloids often exert unique pharmacological effects on animal cells, exposure of sea urchin eggs to nicotine causes polyspermy at fertilization in a dose-dependent manner. Here, we studied molecular mechanisms underlying the phenomenon. Although nicotine is an agonist of ionotropic acetylcholine receptors, we found that nicotine-induced polyspermy was neither mimicked by acetylcholine and carbachol nor inhibited by specific antagonists of nicotinic acetylcholine receptors. Unlike acetylcholine and carbachol, nicotine uniquely induced drastic rearrangement of egg cortical microfilaments in a dose-dependent way. Such cytoskeletal changes appeared to render the eggs more receptive to sperm, as judged by the significant alleviation of polyspermy by latrunculin-A and mycalolide-B. In addition, our fluorimetric assay provided the first evidence that nicotine directly accelerates polymerization kinetics of G-actin and attenuates depolymerization of preassembled F-actin. Furthermore, nicotine inhibited cofilin-induced disassembly of F-actin. Unexpectedly, our results suggest that effects of nicotine can also be mediated in some non-cholinergic pathways.
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19
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Abstract
Synaptotagmin 1 (Syt1) is an abundant and important presynaptic vesicle protein that binds Ca2+ for the regulation of synaptic vesicle exocytosis. Our previous study reported its localization and function on spindle assembly in mouse oocyte meiotic maturation. The present study was designed to investigate the function of Syt1 during mouse oocyte activation and subsequent cortical granule exocytosis (CGE) using confocal microscopy, morpholinol-based knockdown and time-lapse live cell imaging. By employing live cell imaging, we first studied the dynamic process of CGE and calculated the time interval between [Ca2+]i rise and CGE after oocyte activation. We further showed that Syt1 was co-localized to cortical granules (CGs) at the oocyte cortex. After oocyte activation with SrCl2, the Syt1 distribution pattern was altered significantly, similar to the changes seen for the CGs. Knockdown of Syt1 inhibited [Ca2+]i oscillations, disrupted the F-actin distribution pattern and delayed the time of cortical reaction. In summary, as a synaptic vesicle protein and calcium sensor for exocytosis, Syt1 acts as an essential regulator in mouse oocyte activation events including the generation of Ca2+ signals and CGE.
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20
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Sodium-mediated fast electrical depolarization does not prevent polyspermic fertilization in Paracentrotus lividus eggs. ZYGOTE 2019; 27:241-249. [PMID: 31397235 DOI: 10.1017/s0967199419000364] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
During sea urchins fertilization, the activating spermatozoon triggers a series of physiological changes that transforms the quiescent egg into a dynamic zygote. It has been suggested that several of these egg activation events, e.g. sperm-induced plasma membrane depolarization and the Ca2+-linked cortical reaction, play additional roles to prevent the entry of supernumerary spermatozoa. In particular, the abrupt shift in egg membrane potential at fertilization, which is sustained by a Na+ influx, has been considered as a fast mechanism to block polyspermy. To test the relevance of the Na+-mediated fast electrical block to polyspermy, we fertilized sea urchin eggs in artificial seawater with a low concentration of Na+; nearly all the eggs were still monospermic, as judged by the number of Hoechst 33422-stained sperm. When fertilized in normal seawater, eggs that were pre-incubated in the low Na+ medium exhibited impaired elevation of the fertilization envelope. Nevertheless, these eggs manifested entry of a single spermatozoon, suggesting that the fertilization envelope was not the primary determinant of the block to polyspermy. Furthermore, we showed that the abnormal cleavage patterns displayed by eggs pre-incubated in low Na+, which were often considered a hallmark of polyspermy, were due to the alterations in the cortical actin filaments dynamics following fertilization, and not to the formation of multipolar spindles associated with supernumerary sperm centrosomes. Hence, our results suggested that Paracentrotus lividus eggs do not utilize Na+ to rapidly prevent additional spermatozoa from entering the egg, at variance with the hypothesis of an electrical fast block to polyspermy.
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21
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Altered actin cytoskeleton in ageing eggs of starfish affects fertilization process. Exp Cell Res 2019; 381:179-190. [PMID: 31082375 DOI: 10.1016/j.yexcr.2019.05.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 05/03/2019] [Accepted: 05/04/2019] [Indexed: 11/21/2022]
Abstract
Integrity of oocytes is of pivotal interest in the medical and zootechnical practice of in vitro fertilization. With time, oocytes undergo deterioration in quality, and ageing oocytes often exhibit compromised competence in fertilization and the subsequent embryonic development. With ageing oocytes and eggs of starfish (Astropecten aranciacus), we addressed the issue by examining changes of the subcellular structure and their performance at fertilization. Ageing eggs were simulated in two different experimental paradigms: i) oocytes were overmatured by 6 hours stimulation with 1-methyladenine (1-MA); ii) oocytes were removed from the gonad and maintained in seawater for 24 or 48 h before applying the hormonal stimulation (1-MA, 70 min). These eggs were compared with normally matured eggs (stimulated after isolation from the gonad with 1-MA for 70 min) with respect to the sperm-induced intracellular Ca2+ signaling and the structural changes of the egg surface. The cytoskeletal and ultrastructural differences in these eggs were assessed by confocal and transmission electron microscopy, respectively. In the two categories of ageing eggs, we have found remarkable structural modifications of the actin cytoskeleton and the cortical vesicles beneath the plasma membrane. At fertilization, these ageing eggs manifested an altered pattern of intracellular Ca2+ release, aberrant actin dynamics, and increased rate of polyspermy often despite full elevation of the fertilization envelope. Taken together, our results highlight the importance of spatio-temporal regulation of the actin cytoskeleton in the cortex of the eggs, and we postulate that the status of the actin cytoskeleton is one of the major determinants of the oocyte quality that ensures successful monospermic fertilization.
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22
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Vasilev F, Limatola N, Chun JT, Santella L. Contributions of suboolemmal acidic vesicles and microvilli to the intracellular Ca 2+ increase in the sea urchin eggs at fertilization. Int J Biol Sci 2019; 15:757-775. [PMID: 30906208 PMCID: PMC6429021 DOI: 10.7150/ijbs.28461] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Accepted: 12/15/2018] [Indexed: 12/03/2022] Open
Abstract
The onset of fertilization in echinoderms is characterized by instantaneous increase of Ca2+ in the egg cortex, which is called 'cortical flash', and the subsequent Ca2+ wave. While the cortical flash is due to the ion influx through L-type Ca2+ channels in starfish eggs, its amplitude was shown to be affected by the integrity of the egg cortex. Here, we investigated the contribution of cortical granules (CG) and yolk granules (YG) to the sperm-induced Ca2+ signals in sea urchin eggs. To this end, prior to fertilization, Paracentrotus lividus eggs were treated with agents that disrupt or relocate CG beneath the plasma membrane: namely, glycyl-L-phenylalanine 2-naphthylamide (GPN), procaine, urethane, and NH4Cl. All these pretreatments consistently suppressed the cortical flash in the fertilized eggs, and accelerated the decay kinetics of the subsiding Ca2+ wave in most cases. By contrast, centrifugation of the eggs, which stratifies organelles but not the CG, did not exhibit such changes except that the CF was much enhanced in the centrifugal pole where YG are localized. Surprisingly, we noted that pretreatment of the eggs with these CG-disrupting agents or with the inhibitors of L-type Ca2+ channels all drastically reduced the density of the microvilli and their individual shapes on the egg surface. Taken together, our results suggest that the integrity of the egg cortex ensures successful generation of the Ca2+ responses at fertilization, and that modulation of microvilli shape and density may serve as a mechanism of controlling ion flux across the plasma membrane.
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Affiliation(s)
- F Vasilev
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - N Limatola
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - J T Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - L Santella
- Department of Research Infrastructures for Marine Biological Resources, Stazione Zoologica Anton Dohrn, Napoli, Italy
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23
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Maturation and fertilization of echinoderm eggs: Role of actin cytoskeleton dynamics. Biochem Biophys Res Commun 2018; 506:361-371. [DOI: 10.1016/j.bbrc.2018.09.084] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Accepted: 09/13/2018] [Indexed: 01/31/2023]
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24
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Chun JT, Vasilev F, Limatola N, Santella L. Fertilization in Starfish and Sea Urchin: Roles of Actin. Results Probl Cell Differ 2018; 65:33-47. [PMID: 30083914 DOI: 10.1007/978-3-319-92486-1_3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Marine animals relying on "external fertilization" provide advantageous opportunities to study the mechanisms of gamete activation and fusion, as well as the subsequent embryonic development. Owing to the large number of eggs that are easily available and handled, starfish and sea urchins have been chosen as favorable animal models in this line of research for over 150 years. Indeed, much of our knowledge on fertilization came from studies in the echinoderms. Fertilization involves mutual stimulation between eggs and sperm, which leads to morphological, biochemical, and physiological changes on both sides to ensure successful gamete fusion. In this chapter, we review the roles of actin in the fertilization of starfish and sea urchin eggs. As fertilization is essentially an event that takes place on the egg surface, it has been predicted that suboolemmal actin filaments would make significant contributions to sperm entry. A growing body of evidence from starfish and sea urchin eggs suggests that the prompt reorganization of the actin pools around the time of fertilization plays crucial regulatory roles not only in guiding sperm entry but also in modulating intracellular Ca2+ signaling and egg activation.
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Affiliation(s)
- Jong Tai Chun
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy.
| | - Filip Vasilev
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Nunzia Limatola
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy
| | - Luigia Santella
- Department of Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Napoli, Italy.
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25
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De novo assembly of a transcriptome from the eggs and early embryos of Astropecten aranciacus. PLoS One 2017; 12:e0184090. [PMID: 28873438 PMCID: PMC5584759 DOI: 10.1371/journal.pone.0184090] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Accepted: 08/17/2017] [Indexed: 11/19/2022] Open
Abstract
Starfish have been instrumental in many fields of biological and ecological research. Oocytes of Astropecten aranciacus, a common species native to the Mediterranean Sea and the East Atlantic, have long been used as an experimental model to study meiotic maturation, fertilization, intracellular Ca2+ signaling, and cell cycle controls. However, investigation of the underlying molecular mechanisms has often been hampered by the overall lack of DNA or protein sequences for the species. In this study, we have assembled a transcriptome for this species from the oocytes, eggs, zygotes, and early embryos, which are known to have the highest RNA sequence complexity. Annotation of the transcriptome identified over 32,000 transcripts including the ones that encode 13 distinct cyclins and as many cyclin-dependent kinases (CDK), as well as the expected components of intracellular Ca2+ signaling toolkit. Although the mRNAs of cyclin and CDK families did not undergo significant abundance changes through the stages from oocyte to early embryo, as judged by real-time PCR, the transcript encoding Mos, a negative regulator of mitotic cell cycle, was drastically reduced during the period of rapid cleavages. Molecular phylogenetic analysis using the homologous amino acid sequences of cytochrome oxidase subunit I from A. aranciacus and 30 other starfish species indicated that Paxillosida, to which A. aranciacus belongs, is not likely to be the most basal order in Asteroidea. Taken together, the first transcriptome we assembled in this species is expected to enable us to perform comparative studies and to design gene-specific molecular tools with which to tackle long-standing biological questions.
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26
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Development of Ca2+-release mechanisms during oocyte maturation of the starfish Asterina pectinifera. ZYGOTE 2016; 24:857-868. [PMID: 27692029 DOI: 10.1017/s0967199416000186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
An important step for successful fertilization and further development is the increase in intracellular Ca2+ in the activated oocyte. It has been known that starfish oocytes become increasingly sensitive to inositol 1,4,5-trisphosphate (IP3) during meiotic maturation to exhibit highly efficient IP3-induced Ca2+ release (IICR) by the time of germinal vesicle breakdown (GVBD). However, we noted that the peak level of intracellular Ca2+ increase after insemination is already high in the maturing oocytes before GVBD. Using maturing oocytes before GVBD, we investigated Ca2+ release mechanisms other than IICR. We report here that Ca2+-release mechanisms dependent on nicotinic acid adenine dinucleotide phosphate (NAADP) and nicotinamide adenine dinucleotide (NADP), the precursor of NAADP, became functional prior to the development of IICR mechanisms. As with IP3, but unlike NAADP, the Ca2+ stores responsive to NADP are sensitized during the meiotic maturation induced by 1-methyladenine (1-MA). This suggests that the process may represent a physiological response to the maturation hormone. NADP-dependent Ca2+ release in immature oocytes, however, did not induce oocyte maturation by itself, but was enhanced by the conditions mimicking the increases of intracellular Ca2+ and pH that take place in the maturing oocytes of starfish.
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27
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Novel Ca2+ increases in the maturing oocytes of starfish during the germinal vesicle breakdown. Cell Calcium 2015; 58:500-10. [DOI: 10.1016/j.ceca.2015.08.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Revised: 08/04/2015] [Accepted: 08/04/2015] [Indexed: 11/20/2022]
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28
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Assisted yes, but where do we draw the line? Reprod Biomed Online 2015; 31:476-8. [DOI: 10.1016/j.rbmo.2015.06.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Revised: 06/03/2015] [Accepted: 06/23/2015] [Indexed: 11/18/2022]
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29
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Guo H, Garcia-Vedrenne AE, Isserlin R, Lugowski A, Morada A, Sun A, Miao Y, Kuzmanov U, Wan C, Ma H, Foltz K, Emili A. Phosphoproteomic network analysis in the sea urchin Strongylocentrotus purpuratus
reveals new candidates in egg activation. Proteomics 2015; 15:4080-95. [DOI: 10.1002/pmic.201500159] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Revised: 06/16/2015] [Accepted: 07/23/2015] [Indexed: 12/20/2022]
Affiliation(s)
- Hongbo Guo
- Donnelly Centre for Cellular and Biomolecular Research; University of Toronto; Toronto ON Canada
| | | | - Ruth Isserlin
- Donnelly Centre for Cellular and Biomolecular Research; University of Toronto; Toronto ON Canada
| | - Andrew Lugowski
- Donnelly Centre for Cellular and Biomolecular Research; University of Toronto; Toronto ON Canada
| | - Anthony Morada
- Department of Molecular, Cellular and Developmental Biology, and Marine Science Institute; Santa Barbara CA USA
| | - Alex Sun
- Department of Molecular, Cellular and Developmental Biology, and Marine Science Institute; Santa Barbara CA USA
| | - Yishen Miao
- Department of Molecular, Cellular and Developmental Biology, and Marine Science Institute; Santa Barbara CA USA
| | - Uros Kuzmanov
- Donnelly Centre for Cellular and Biomolecular Research; University of Toronto; Toronto ON Canada
| | - Cuihong Wan
- Donnelly Centre for Cellular and Biomolecular Research; University of Toronto; Toronto ON Canada
| | - Hongyue Ma
- Collaborative Innovation Center of Chinese Medicinal Resources Industrialization; College of Pharmacy; Nanjing University of Chinese Medicine; Nanjing P. R. China
| | - Kathy Foltz
- Department of Molecular, Cellular and Developmental Biology, and Marine Science Institute; Santa Barbara CA USA
| | - Andrew Emili
- Donnelly Centre for Cellular and Biomolecular Research; University of Toronto; Toronto ON Canada
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30
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Santella L, Limatola N, Chun JT. Calcium and actin in the saga of awakening oocytes. Biochem Biophys Res Commun 2015; 460:104-13. [PMID: 25998739 DOI: 10.1016/j.bbrc.2015.03.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 03/06/2015] [Indexed: 12/12/2022]
Abstract
The interaction of the spermatozoon with the egg at fertilization remains one of the most fascinating mysteries of life. Much of our scientific knowledge on fertilization comes from studies on sea urchin and starfish, which provide plenty of gametes. Large and transparent, these eggs have served as excellent model systems for studying egg activation and embryo development in seawater, a plain natural medium. Starfish oocytes allow the study of the cortical, cytoplasmic and nuclear changes during the meiotic maturation process, which can also be triggered in vitro by hormonal stimulation. These morphological and biochemical changes ensure successful fertilization of the eggs at the first metaphase. On the other hand, sea urchin eggs are fertilized after the completion of meiosis, and are particularly suitable for the study of sperm-egg interaction, early events of egg activation, and embryonic development, as a large number of mature eggs can be fertilized synchronously. Starfish and sea urchin eggs undergo abrupt changes in the cytoskeleton and ion fluxes in response to the fertilizing spermatozoon. The plasma membrane and cortex of an egg thus represent "excitable media" that quickly respond to the stimulus with the Ca(2+) swings and structural changes. In this article, we review some of the key findings on the rapid dynamic rearrangements of the actin cytoskeleton in the oocyte/egg cortex upon hormonal or sperm stimulation and their roles in the modulation of the Ca(2+) signals and in the control of monospermic fertilization.
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Affiliation(s)
- Luigia Santella
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale 1, Napoli, I-80121, Italy.
| | - Nunzia Limatola
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale 1, Napoli, I-80121, Italy
| | - Jong T Chun
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale 1, Napoli, I-80121, Italy
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Holt WV, Fazeli A. Do sperm possess a molecular passport? Mechanistic insights into sperm selection in the female reproductive tract. ACTA ACUST UNITED AC 2015; 21:491-501. [DOI: 10.1093/molehr/gav012] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Accepted: 03/04/2015] [Indexed: 12/26/2022]
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Soluble sperm extract specifically recapitulates the initial phase of the Ca2+ response in the fertilized oocyte of P. occelata following a G-protein/ PLCβ signaling pathway. ZYGOTE 2014; 23:821-35. [PMID: 25318389 DOI: 10.1017/s0967199414000501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Matured oocytes of the annelidan worm Pseudopotamilla occelata are fertilized at the first metaphase of the meiotic division. During the activation by fertilizing spermatozoa, the mature oocyte shows a two-step intracellular Ca2+ increase. Whereas the first Ca2+ increase is localized and appears to utilize the inositol 1,4,5-trisphosphate (IP3)-sensitive Ca2+ stores, the second Ca2+ increase is global and involves Ca2+ influx via voltage-gated Ca2+ channels on the entire surface of the oocyte. To study how sperm trigger the Ca2+ increases during fertilization, we prepared soluble sperm extract (SE) and examined its ability to induce Ca2+ increases in the oocyte. The SE could evoke a Ca2+ increase in the oocyte when it was added to the medium, but not when it was delivered by microinjection. However, the second-step Ca2+ increase leading to the resumption of meiosis did not follow in these eggs. Local application of SE induced a non-propagating Ca2+ increase and formed a cytoplasmic protrusion that was similar to that created by the fertilizing sperm at the first stage of the Ca2+ response, important for sperm incorporation into the oocyte. Our results suggest that the fertilizing spermatozoon may trigger the first-step Ca2+ increase before it fuses with the oocyte in a pathway that involves the G-protein-coupled receptor and phospholipase C. Thus, the first phase of the Ca2+ response in the fertilized egg of this species is independent of the second phase of the Ca2+ increase for egg activation.
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Chun JT, Limatola N, Vasilev F, Santella L. Early events of fertilization in sea urchin eggs are sensitive to actin-binding organic molecules. Biochem Biophys Res Commun 2014; 450:1166-74. [DOI: 10.1016/j.bbrc.2014.06.057] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 06/11/2014] [Indexed: 10/25/2022]
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Lennarz WJ, Santella L. Introduction. Fertilization and early development. Biochem Biophys Res Commun 2014; 450:1133-4. [PMID: 25112583 DOI: 10.1016/j.bbrc.2014.07.091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Dale B. Is the idea of a fast block to polyspermy based on artifact? Biochem Biophys Res Commun 2014; 450:1159-65. [DOI: 10.1016/j.bbrc.2014.03.157] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2014] [Accepted: 03/31/2014] [Indexed: 01/25/2023]
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Nakano T, Deguchi R, Kyozuka K. Intracellular calcium signaling in the fertilized eggs of Annelida. Biochem Biophys Res Commun 2014; 450:1188-94. [PMID: 24953697 DOI: 10.1016/j.bbrc.2014.06.056] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/11/2014] [Indexed: 11/19/2022]
Abstract
Fertilization is such a universal and indispensable step in sexual reproduction, but a high degree of variability exists in the way it takes place in the animal kingdom. As discussed in other reviews in this issue, recent works on this subject clarified many points. However, important results on the mechanisms of fertilization are obtained mainly from a few restricted model organisms. In this sense, it is utterly important to collect more information from various phyla. In this review, we have re-introduced Annelida as one of the most suitable models for the analysis of fertilization process. We have briefly reviewed the historical works on the fertilization of Annelida. Then, we have described recent findings on the two independent Ca(2+) increases in the fertilized eggs of Annelida, which arise from two different mechanisms and may have distinct physiological roles toward sperm entry and egg activation. We propose that the Ca(2+) increase in the fertilized eggs reflect the specific needs of the zygote in a given species.
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Affiliation(s)
- Takeshi Nakano
- Research Center for Marine Biology, Asamushi, Graduate School of Life Science, Tohoku University Asamushi, Aomori 039-3501, Japan.
| | - Ryusaku Deguchi
- Department of Biology, Miyagi University of Education, Sendai, Miyagi 980-0845, Japan.
| | - Keiichiro Kyozuka
- Research Center for Marine Biology, Asamushi, Graduate School of Life Science, Tohoku University Asamushi, Aomori 039-3501, Japan.
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Secretagogue stimulation of neurosecretory cells elicits filopodial extensions uncovering new functional release sites. J Neurosci 2014; 33:19143-53. [PMID: 24305811 DOI: 10.1523/jneurosci.2634-13.2013] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Regulated exocytosis in neurosecretory cells relies on the timely fusion of secretory granules (SGs) with the plasma membrane. Secretagogue stimulation leads to an enlargement of the cell footprint (surface area in contact with the coverslip), an effect previously attributed to exocytic fusion of SGs with the plasma membrane. Using total internal reflection fluorescence microscopy, we reveal the formation of filopodia-like structures in bovine chromaffin and PC12 cells driving the footprint expansion, suggesting the involvement of cortical actin network remodeling in this process. Using exocytosis-incompetent PC12 cells, we demonstrate that footprint enlargement is largely independent of SG fusion, suggesting that vesicular exocytic fusion plays a relatively minor role in filopodial expansion. The footprint periphery, including filopodia, undergoes extensive F-actin remodeling, an effect abolished by the actomyosin inhibitors cytochalasin D and blebbistatin. Imaging of both Lifeact-GFP and the SG marker protein neuropeptide Y-mCherry reveals that SGs actively translocate along newly forming actin tracks before undergoing fusion. Together, these data demonstrate that neurosecretory cells regulate the number of SGs undergoing exocytosis during sustained stimulation by controlling vesicular mobilization and translocation to the plasma membrane through actin remodeling. Such remodeling facilitates the de novo formation of fusion sites.
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Chun JT, Vasilev F, Santella L. Antibody against the actin-binding protein depactin attenuates Ca2+ signaling in starfish eggs. Biochem Biophys Res Commun 2013; 441:301-7. [DOI: 10.1016/j.bbrc.2013.09.103] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Accepted: 09/20/2013] [Indexed: 10/26/2022]
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Santella L, Vasilev F, Chun JT. Fertilization in echinoderms. Biochem Biophys Res Commun 2012; 425:588-94. [PMID: 22925679 DOI: 10.1016/j.bbrc.2012.07.159] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 07/28/2012] [Indexed: 11/27/2022]
Abstract
For more than 150 years, echinoderm eggs have served as overly favored experimental model systems in which to study fertilization. Sea urchin and starfish belong to the same phylum and thus share many similarities in their fertilization patterns. However, several subtle but fundamental differences do exist in the fertilization of sea urchin and starfish, reflecting their phylogenetic bifurcation approximately 500 million years ago. In this article we review some of the seminal and recent findings that feature similarities and differences in sea urchin and starfish at fertilization.
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Affiliation(s)
- Luigia Santella
- Laboratory of Cellular and Developmental Biology Stazione Zoologica Anton Dohrn, Villa Comunale 1, Napoli 80121, Italy.
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Kinsey WH. Intersecting roles of protein tyrosine kinase and calcium signaling during fertilization. Cell Calcium 2012. [PMID: 23201334 DOI: 10.1016/j.ceca.2012.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The oocyte is a highly specialized cell that must respond to fertilization with a preprogrammed series of signal transduction events that establish a block to polyspermy, trigger resumption of the cell cycle and execution of a developmental program. The fertilization-induced calcium transient is a key signal that initiates the process of oocyte activation and studies over the last several years have examined the signaling pathways that act upstream and downstream of this calcium transient. Protein tyrosine kinase signaling was found to be an important component of the upstream pathways that stimulated calcium release at fertilization in oocytes from animals that fertilize externally, but a similar pathway has not been found in mammals which fertilize internally. The following review will examine the diversity of signaling in oocytes from marine invertebrates, amphibians, fish and mammals in an attempt to understand the basis for the observed differences. In addition to the pathways upstream of the fertilization-induced calcium transient, recent studies are beginning to unravel the role of protein tyrosine kinase signaling downstream of the calcium transient. The PYK2 kinase was found to respond to fertilization in the zebrafish system and seems to represent a novel component of the response of the oocyte to fertilization. The potential impact of impaired PTK signaling in oocyte quality will also be discussed.
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Affiliation(s)
- William H Kinsey
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, United States.
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Vasilev F, Chun JT, Gragnaniello G, Garante E, Santella L. Effects of ionomycin on egg activation and early development in starfish. PLoS One 2012; 7:e39231. [PMID: 22723970 PMCID: PMC3377674 DOI: 10.1371/journal.pone.0039231] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Accepted: 05/21/2012] [Indexed: 11/21/2022] Open
Abstract
Ionomycin is a Ca2+-selective ionophore that is widely used to increase intracellular Ca2+ levels in cell biology laboratories. It is also occasionally used to activate eggs in the clinics practicing in vitro fertilization. However, neither the precise molecular action of ionomycin nor its secondary effects on the eggs' structure and function is well known. In this communication we have studied the effects of ionomycin on starfish oocytes and zygotes. By use of confocal microscopy, calcium imaging, as well as light and transmission electron microscopy, we have demonstrated that immature oocytes exposed to ionomycin instantly increase intracellular Ca2+ levels and undergo structural changes in the cortex. Surprisingly, when microinjected into the cells, ionomycin produced no Ca2+ increase. The ionomycin-induced Ca2+ rise was followed by fast alteration of the actin cytoskeleton displaying conspicuous depolymerization at the oocyte surface and in microvilli with concomitant polymerization in the cytoplasm. In addition, cortical granules were disrupted or fused with white vesicles few minutes after the addition of ionomycin. These structural changes prevented cortical maturation of the eggs despite the normal progression of nuclear envelope breakdown. At fertilization, the ionomycin-pretreated eggs displayed reduced Ca2+ response, no elevation of the fertilization envelope, and the lack of orderly centripetal translocation of actin fibers. These alterations led to difficulties in cell cleavage in the monospermic zygotes and eventually to a higher rate of abnormal development. In conclusion, ionomycin has various deleterious impacts on egg activation and the subsequent embryonic development in starfish. Although direct comparison is difficult to make between our findings and the use of the ionophore in the in vitro fertilization clinics, our results call for more defining investigations on the issue of a potential risk in artificial egg activation.
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Affiliation(s)
- Filip Vasilev
- Laboratory of Cellular and Developmental Biology, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy
| | - Jong T. Chun
- Laboratory of Cellular and Developmental Biology, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy
| | - Giovanni Gragnaniello
- Laboratory of Cellular and Developmental Biology, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy
| | - Ezio Garante
- Laboratory of Cellular and Developmental Biology, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy
| | - Luigia Santella
- Laboratory of Cellular and Developmental Biology, Stazione Zoologica Anton Dohrn, Villa Comunale, Napoli, Italy
- * E-mail:
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Sun SC, Gao WW, Xu YN, Jin YX, Wang QL, Yin XJ, Cui XS, Kim NH. Degradation of actin nucleators affects cortical polarity of aged mouse oocytes. Fertil Steril 2012; 97:984-90. [PMID: 22306711 DOI: 10.1016/j.fertnstert.2012.01.101] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 01/12/2012] [Accepted: 01/12/2012] [Indexed: 11/17/2022]
Abstract
OBJECTIVE To investigate the molecular mechanism of mouse oocyte polarity loss during aging. DESIGN Experimental study. SETTING Academic basic research laboratory. ANIMAL(S) Mice. INTERVENTION(S) Oocytes were collected 16 hours after injection of hCG and cultured in M16 medium for an additional 14 hours with or without caffeine. MAIN OUTCOME MEASURE(S) Expression and localizations of actin nucleators actin-related protein 2/3 complex, JMY, and WAVE2 were examined by immunofluorescence staining, and their messenger RNA levels were examined by real-time reverse transcription-polymerase chain reaction. RESULT(S) The protein and messenger RNA levels of actin-related protein 2/3 complex, JMY, and WAVE2 were decreased in aged oocytes, but the levels were normal in caffeine-treated aged oocytes. CONCLUSION(S) Our data indicated that the loss of oocyte polarity may be due to the degradation of actin nucleators in aged oocytes.
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Affiliation(s)
- Shao-Chen Sun
- Department of Animal Sciences, Chungbuk National University, Cheongju, Chungbuk, South Korea
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Johnston WL, Dennis JW. The eggshell in the C. elegans oocyte-to-embryo transition. Genesis 2011; 50:333-49. [PMID: 22083685 DOI: 10.1002/dvg.20823] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 10/28/2011] [Accepted: 10/31/2011] [Indexed: 12/13/2022]
Abstract
In egg-laying animals, embryonic development takes place within the highly specialized environment provided by the eggshell and its underlying extracellular matrix. Far from being simply a passive physical support, the eggshell is a key player in many early developmental events. Herein, we review current understanding of eggshell structure, biosynthesis, and function in zygotic development of the nematode, C. elegans. Beginning at sperm contact or entry, eggshell layers are produced sequentially. The earlier outer layers are required for secretion or organization of inner layers, and layers differ in composition and function. Developmental events that depend on the eggshell include polyspermy barrier generation, high fidelity meiotic chromosome segregation, osmotic barrier synthesis, polar body extrusion, anterior-posterior polarization, and organization of membrane and cortical proteins. The C. elegans eggshell is proving to be an excellent, tractable system to study the molecular cues of the extracellular matrix that instruct cell polarity and early development.
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Affiliation(s)
- Wendy L Johnston
- Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada, M5G 1X5.
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Actin, more than just a housekeeping protein at the scene of fertilization. SCIENCE CHINA-LIFE SCIENCES 2011; 54:733-43. [DOI: 10.1007/s11427-011-4202-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2011] [Accepted: 06/20/2011] [Indexed: 10/18/2022]
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Dale B, DeFelice L. Polyspermy prevention: facts and artifacts? J Assist Reprod Genet 2011; 28:199-207. [PMID: 21104196 PMCID: PMC3082659 DOI: 10.1007/s10815-010-9513-5] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Accepted: 11/09/2010] [Indexed: 11/30/2022] Open
Abstract
The purpose of this review is to open a debate as to whether or not oocytes actively repel supernumerary sperm or in nature final sperm: oocyte ratios are so low that polyspermy preventing mechanisms are not necessary. Before encountering the oocyte, spermatozoa need to be primed, either by environmental factors as in animals exhibiting external fertilization, or by factors from the female reproductive tract, as in mammals. The spermatozoon must then recognize and interact with the outer layers of the oocyte and progression of the fertilizing spermatozoon through these layers is further controlled and modulated by a precise sequence of signals in situ. Removal of these outer coats may not inhibit fertilization, however does interfere with the dynamics of sperm-oocyte interaction. We propose that monospermy in mammals and sea urchins, under natural conditions, is ensured by the controlled and gradual encounter of a minimum number of spermatozoa with the oocyte and that fine tuning is ensured by the structural and molecular organization of the oocyte and its surrounding coats. We suggest that laboratory experiments using oocytes deprived of their investments and exposed to unnaturally high concentrations of spermatozoa are artifactual and argue that the conclusions leading to the hypothesis of a fast electrical block to polyspermy are unfounded. Under laboratory conditions the majority of spermatozoa, although motile and capable of attaching to the oocyte surface, are either physiologically incompetent or attach to areas of the oocyte surface that do not support entry.
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Affiliation(s)
- Brian Dale
- Centre for Assisted Fertilization, Naples, Italy.
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The biphasic increase of PIP2 in the fertilized eggs of starfish: new roles in actin polymerization and Ca2+ signaling. PLoS One 2010; 5:e14100. [PMID: 21124897 PMCID: PMC2990714 DOI: 10.1371/journal.pone.0014100] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2010] [Accepted: 11/01/2010] [Indexed: 12/17/2022] Open
Abstract
Background Fertilization of echinoderm eggs is accompanied by dynamic changes of the actin cytoskeleton and by a drastic increase of cytosolic Ca2+. Since the plasma membrane-enriched phospholipid phosphatidylinositol 4,5-bisphosphate (PIP2) serves as the precursor of inositol 1,4,5 trisphosphate (InsP3) and also regulates actin-binding proteins, PIP2 might be involved in these two processes. Methodology/Principal Findings In this report, we have studied the roles of PIP2 at fertilization of starfish eggs by using fluorescently tagged pleckstrin homology (PH) domain of PLC-δ1, which has specific binding affinity to PIP2, in combination with Ca2+ and F-actin imaging techniques and transmission electron microscopy. During fertilization, PIP2 increased at the plasma membrane in two phases rather than continually decreasing. The first increase was quickly followed by a decrease about 40 seconds after sperm-egg contact. However, these changes took place only after the Ca2+ wave had already initiated and propagated. The fertilized eggs then displayed a prolonged increase of PIP2 that was accompanied by the appearance of numerous spikes in the perivitelline space during the elevation of the fertilization envelope (FE). These spikes, protruding from the plasma membrane, were filled with microfilaments. Sequestration of PIP2 by RFP-PH at higher doses resulted in changes of subplasmalemmal actin networks which significantly delayed the intracellular Ca2+ signaling, impaired elevation of FE, and increased occurrences of polyspermic fertilization. Conclusions/Significance Our results suggest that PIP2 plays comprehensive roles in shaping Ca2+ waves and guiding structural and functional changes required for successful fertilization. We propose that the PIP2 increase and the subsequent formation of actin spikes not only provide the mechanical supports for the elevating FE, but also accommodate increased membrane surfaces during cortical granule exocytosis.
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Eggshell chitin and chitin-interacting proteins prevent polyspermy in C. elegans. Curr Biol 2010; 20:1932-7. [PMID: 20971008 DOI: 10.1016/j.cub.2010.09.059] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Revised: 07/23/2010] [Accepted: 09/23/2010] [Indexed: 11/21/2022]
Abstract
Development requires fertilization by a single sperm. In Caenorhabditis elegans, fertilization occurs in a sperm-filled spermatheca, implying the barrier to polyspermy is generated in this compartment. Eggshell chitin synthesis is initiated at fertilization, and chitin is deposited before the zygote exits the spermatheca. Whereas polyspermy is very rare in wild-type, here we report an incidence of 14%-51% in zygotes made chitin deficient by loss of chitin synthase-1 (CHS-1), the CHS-1 substrate UDP-N-acetylglucosamine, the CHS-1-interacting protein EGG-3, or the sperm-provided protein SPE-11. The spe-11(hc90) mutant deposits chitin at the male end but fails to complete a continuous layer. The polyspermy barrier is also compromised by loss of the chitin-binding protein CBD-1 or the GLD-1-regulated LDL receptor-like EGG-1, together with its homolog, EGG-2. Loss of CBD-1 or EGG-1/2 disrupts oocyte cortical distribution of CHS-1, as well as MBK-2 and EGG-3. In CBD-1 or EGG-1/2 deficiency, chitin is synthesized but the eggshell is fractured, suggesting aberrantly clustered CHS-1/MBK-2/EGG-3 may fail to support construction of a continuous eggshell. Together, our results show that eggshell chitin is required to prevent polyspermy in C. elegans, in addition to its previously reported requirement in polar body extrusion and polarization of the zygote.
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Abstract
The dynamic remolding of the actin cytoskeleton is a critical part of most cellular activities, and malfunction of cytoskeletal proteins results in various human diseases. The transition between two forms of actin, monomeric or G-actin and filamentous or F-actin, is tightly regulated in time and space by a large number of signaling, scaffolding and actin-binding proteins (ABPs). New ABPs are constantly being discovered in the post-genomic era. Most of these proteins are modular, integrating actin binding, protein-protein interaction, membrane-binding, and signaling domains. In response to extracellular signals, often mediated by Rho family GTPases, ABPs control different steps of actin cytoskeleton assembly, including filament nucleation, elongation, severing, capping, and depolymerization. This review summarizes structure-function relationships among ABPs in the regulation of actin cytoskeleton assembly.
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Affiliation(s)
- Sung Haeng Lee
- Chosun University School of Medicine, Department of Cellular and Molecular Medicine, Gwangju 501-759, Korea.
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Impact of marine drugs on cytoskeleton-mediated reproductive events. Mar Drugs 2010; 8:881-915. [PMID: 20479959 PMCID: PMC2866467 DOI: 10.3390/md8040881] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 03/02/2010] [Accepted: 03/23/2010] [Indexed: 12/30/2022] Open
Abstract
Marine organisms represent an important source of novel bioactive compounds, often showing unique modes of action. Such drugs may be useful tools to study complex processes such as reproduction; which is characterized by many crucial steps that start at gamete maturation and activation and virtually end at the first developmental stages. During these processes cytoskeletal elements such as microfilaments and microtubules play a key-role. In this review we describe: (i) the involvement of such structures in both cellular and in vitro processes; (ii) the toxins that target the cytoskeletal elements and dynamics; (iii) the main steps of reproduction and the marine drugs that interfere with these cytoskeleton-mediated processes. We show that marine drugs, acting on microfilaments and microtubules, exert a wide range of impacts on reproductive events including sperm maturation and motility, oocyte maturation, fertilization, and early embryo development.
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Guanine nucleotides in the meiotic maturation of starfish oocytes: regulation of the actin cytoskeleton and of Ca(2+) signaling. PLoS One 2009; 4:e6296. [PMID: 19617909 PMCID: PMC2706993 DOI: 10.1371/journal.pone.0006296] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2009] [Accepted: 06/15/2009] [Indexed: 11/19/2022] Open
Abstract
Background Starfish oocytes are arrested at the first prophase of meiosis until they are stimulated by 1-methyladenine (1-MA). The two most immediate responses to the maturation-inducing hormone are the quick release of intracellular Ca2+ and the accelerated changes of the actin cytoskeleton in the cortex. Compared with the later events of oocyte maturation such as germinal vesicle breakdown, the molecular mechanisms underlying the early events involving Ca2+ signaling and actin changes are poorly understood. Herein, we have studied the roles of G-proteins in the early stage of meiotic maturation. Methodology/Principal Findings By microinjecting starfish oocytes with nonhydrolyzable nucleotides that stabilize either active (GTPγS) or inactive (GDPβS) forms of G-proteins, we have demonstrated that: i) GTPγS induces Ca2+ release that mimics the effect of 1-MA; ii) GDPβS completely blocks 1-MA-induced Ca2+; iii) GDPβS has little effect on the amplitude of the Ca2+ peak, but significantly expedites the initial Ca2+ waves induced by InsP3 photoactivation, iv) GDPβS induces unexpectedly striking modification of the cortical actin networks, suggesting a link between the cytoskeletal change and the modulation of the Ca2+ release kinetics; v) alteration of cortical actin networks with jasplakinolide, GDPβS, or actinase E, all led to significant changes of 1-MA-induced Ca2+ signaling. Conclusions/Significance Taken together, these results indicate that G-proteins are implicated in the early events of meiotic maturation and support our previous proposal that the dynamic change of the actin cytoskeleton may play a regulatory role in modulating intracellular Ca2+ release.
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