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Identification of SH2 Domain-Mediated Protein Interactions that Operate at Fertilization in the Sea Star Patiria miniata. Methods Mol Biol 2021. [PMID: 33074537 DOI: 10.1007/978-1-0716-0974-3_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
The signaling mechanisms controlling internal calcium release at fertilization in animals are still largely unknown. Echinoderms, such as the sea star Patiria miniata, produce abundant and easily accessible sperm and eggs. In addition, eggs are naturally synchronized at the same cell cycle stage, collectively making these animals an attractive model to study the signaling proteins controlling fertilization. However, the lack of antibodies to identify proteins in this model system has slowed progress in identifying key signaling molecules. With the advances in mass spectrometry, we present a method for identifying tyrosine phosphorylated proteins binding to GST-tagged SH2 domains in sea star cell lysates for downstream mass spectrometry analysis.
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Early and later studies on action potential and fertilization potential of echinoderm oocytes and Ca 2+ response of mammalian oocytes. Methods Cell Biol 2019. [PMID: 30948005 DOI: 10.1016/bs.mcb.2019.03.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/10/2024]
Abstract
This is a personal essay starting from the early study on fertilization signals in echinoderm and mammalian oocytes. It presents actual examples showing that a unexpected discovery leads to unimaginable development of the research in diverse directions in later years and yields a common concept after long years' effort and accumulation. Those outcomes are the happiest gift for researchers. We also learn many precepts in our own research life.
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Cui P, Ma T, Tamadon A, Han S, Li B, Chen Z, An X, Shao LR, Wang Y, Feng Y. Hypothalamic DNA methylation in rats with dihydrotestosterone-induced polycystic ovary syndrome: effects of low-frequency electro-acupuncture. Exp Physiol 2018; 103:1618-1632. [DOI: 10.1113/ep087163] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Accepted: 09/10/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Peng Cui
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology; Fudan Institutes of Integrative Medicine; Fudan University; Shanghai 200032 China
| | - Tong Ma
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology; Fudan Institutes of Integrative Medicine; Fudan University; Shanghai 200032 China
| | - Amin Tamadon
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology; Fudan Institutes of Integrative Medicine; Fudan University; Shanghai 200032 China
| | - Sha Han
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology; Fudan Institutes of Integrative Medicine; Fudan University; Shanghai 200032 China
| | - Bing Li
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology; Fudan Institutes of Integrative Medicine; Fudan University; Shanghai 200032 China
| | - Zheyi Chen
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology; Fudan Institutes of Integrative Medicine; Fudan University; Shanghai 200032 China
| | - Xiaofei An
- Department of Endocrinology, Jiangsu Province Hospital of Chinese Medicine; Affiliated Hospital of Nanjing University of Chinese Medicine; Nanjing 210029 China
| | - Linus R. Shao
- Department of Physiology/Endocrinology, Institute of Neuroscience and Physiology, The Sahlgrenska Academy; University of Gothenburg; 40530 Gothenburg Sweden
| | - Yanqing Wang
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology; Fudan Institutes of Integrative Medicine; Fudan University; Shanghai 200032 China
- Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function
| | - Yi Feng
- Department of Integrative Medicine and Neurobiology, School of Basic Medical Sciences, Institutes of Brain Science, State Key Laboratory of Medical Neurobiology; Fudan Institutes of Integrative Medicine; Fudan University; Shanghai 200032 China
- Shanghai Key Laboratory of Acupuncture Mechanism and Acupoint Function
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Abstract
A common early feature in the activation of all eggs during fertilisation is an increase in the level of intra-cellular free calcium (Ca2+) that, in most species, propagates as a wave across the egg (reviewed in Strieker, 1999). In echinoderms, this Ca2+ release is the result of a signal transduction cascade that requires phospholipase Cγ (PLCγ)-mediated production of inositol trisphosphate (IP3) (Carroll et al., 1997, 1999). PLCγ is most commonly regulated by tyrosine phosphorylation (Rhee & Bae, 1997), indicating that a tyrosine kinase is a likely upstream regulator of PLCγ enzymatic activity at fertilisation. In support of this hypothesis, an increase in tyrosine kinase activity and an increase in tyrosine-phosphorylated proteins at fertilisation has been observed in echinoderm eggs (Satoh & Garbers, 1985; Ciapa & Epel, 1991; Kinsey, 1997). Moreover, the tyrosine kinase inhibitors genistein (Shen et al., 1999) and PP1 (Abassi et al., 2000) have been used to show that in sea urchin eggs a tyrosine kinase activity is required for normal Ca2+ release in response to fertilisation.In eggs of the starfish Asterina miniata, a Src-type tyrosine kinase has been identified as a potential regulator of PLCγ activity at fertilisation (Giusti et al., 1999a). This kinase exhibits a rapid fertilisation-dependent association specifically with the Src Homology 2 (SH2) domains of PLCγ. Moreover, the timing of this association correlates with an increase in the tyrosine kinase activity bound to the PLCγ SH2 domains, and neither the Src kinase nor the associated kinase activity was observed to associate with the PLCγ SH2 domains after treating eggs with the calcium ionophore A23187 (Giusti et al., 1999a). These data identify an egg Src family kinase as a potential upstream regulator of PLCγ during starfish egg fertilisation.
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Wiseman E, Bates L, Dubé A, Carroll DJ. Starfish as a Model System for Analyzing Signal Transduction During Fertilization. Results Probl Cell Differ 2018; 65:49-67. [PMID: 30083915 DOI: 10.1007/978-3-319-92486-1_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/17/2023]
Abstract
The starfish oocyte and egg offer advantages for use as a model system for signal transduction research. Some of these have been recognized for over a century, including the ease of procuring gametes, in vitro fertilization, and culturing the embryos. New advances, particularly in genomics, have also opened up opportunities for the use of these animals. In this chapter, we give a few examples of the historical use of the starfish for research in cell biology and then describe some new areas in which we believe the starfish can contribute to our understanding of signal transduction-particularly in fertilization.
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Affiliation(s)
- Emily Wiseman
- Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL, USA
| | - Lauren Bates
- Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL, USA
| | - Altair Dubé
- Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL, USA
| | - David J Carroll
- Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL, USA.
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6
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Abstract
Vertebrate reproduction requires a myriad of precisely orchestrated events-in particular, the maternal production of oocytes, the paternal production of sperm, successful fertilization, and initiation of early embryonic cell divisions. These processes are governed by a host of signaling pathways. Protein kinase and phosphatase signaling pathways involving Mos, CDK1, RSK, and PP2A regulate meiosis during maturation of the oocyte. Steroid signals-specifically testosterone-regulate spermatogenesis, as does signaling by G-protein-coupled hormone receptors. Finally, calcium signaling is essential for both sperm motility and fertilization. Altogether, this signaling symphony ensures the production of viable offspring, offering a chance of genetic immortality.
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Affiliation(s)
- Sally Kornbluth
- Duke University School of Medicine, Durham, North Carolina 27710
| | - Rafael Fissore
- University of Massachusetts, Amherst, Veterinary and Animal Sciences, Amherst, Massachusetts 01003
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7
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Sato KI. Transmembrane signal transduction in oocyte maturation and fertilization: focusing on Xenopus laevis as a model animal. Int J Mol Sci 2014; 16:114-34. [PMID: 25546390 PMCID: PMC4307238 DOI: 10.3390/ijms16010114] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Accepted: 12/15/2014] [Indexed: 11/16/2022] Open
Abstract
Fertilization is a cell biological phenomenon of crucial importance for the birth of new life in a variety of multicellular and sexual reproduction species such as algae, animal and plants. Fertilization involves a sequence of events, in which the female gamete "egg" and the male gamete "spermatozoon (sperm)" develop, acquire their functions, meet and fuse with each other, to initiate embryonic and zygotic development. Here, it will be briefly reviewed how oocyte cytoplasmic components are orchestrated to undergo hormone-induced oocyte maturation and sperm-induced activation of development. I then review how sperm-egg membrane interaction/fusion and activation of development in the fertilized egg are accomplished and regulated through egg coat- or egg plasma membrane-associated components, highlighting recent findings and future directions in the studies using Xenopus laevis as a model experimental animal.
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Affiliation(s)
- Ken-ichi Sato
- Laboratory of Cell Signaling and Development, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Kyoto 603-8555, Japan.
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8
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Cihal S, Carroll DJ. Biotinylation of oocyte cell surface proteins of the starfish Patiria miniata. Methods Mol Biol 2014; 1128:197-209. [PMID: 24567216 DOI: 10.1007/978-1-62703-974-1_13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Understanding the signal transduction processes that occur during oocyte maturation and fertilization requires knowledge of the constituent proteins from the cell surface to relevant intracellular compartments. To identify starfish oocyte and egg cell surface proteins, a biotinylation method was adapted from prior protocols using B cells, leukocytes, mouse oocytes, and sea urchin eggs (Cole et al. Mol Immunol 24:699-705, 1987; Flaherty and Swann NJ. Mol Reprod Dev 35:285-292, 1993; Haley and Wessel. Dev Biol 272:191-202, 2004; Hurley et al. J Immunol Methods 85:195-202, 1985). This method utilizes the water-soluble Sulfo-NHS-Biotin, which does not cross the egg plasma membrane. The process of biotinylation does not appear to have any effect on the process of oocyte maturation or fertilization. Furthermore, it can be used with either vitelline-intact or vitelline-free oocytes and allows the proteins to be visualized successfully through immunoblotting, immunoprecipitation, or by scanning confocal microscopy.
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Affiliation(s)
- Samantha Cihal
- Department of Biological Sciences, Florida Institute of Technology, Melbourne, FL, USA
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9
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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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Tosca L, Glass R, Bronchain O, Philippe L, Ciapa B. PLCγ, G-protein of the Gαq type and cADPr pathway are associated to trigger the fertilization Ca2+ signal in the sea urchin egg. Cell Calcium 2012; 52:388-96. [PMID: 22784667 DOI: 10.1016/j.ceca.2012.06.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 06/19/2012] [Accepted: 06/20/2012] [Indexed: 11/18/2022]
Abstract
In all species, fertilization triggers in the egg a rapid and transient increase of intracellular free calcium (Cai), but how this signal is generated following sperm and egg interaction has not been clearly characterised yet. In sea urchin, a signalling pathway involving tyrosine kinase and PLCγ has been proposed to be at the origin of the fertilization Cai signal. We report here that injection of src homology-2 (SH2) domains of the sea urchin PLCγ inhibits in a competitive manner the endogenous PLCγ, alters both the amplitude and duration of the fertilization Cai wave, but does not abrogate it. Our results suggest that PLCγ acts in conjunction with a cADPr pathway and G-proteins of the Gαq type to trigger the fertilization Cai wave, and reinforce a crucial role for PLCγ at mitosis and cytokinesis.
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Affiliation(s)
- Lucie Tosca
- INSERM U935/Université Paris Sud/AP-HP, Histologie-Embryologie-Cytogénétique, Hôpital Antoine Béclère, 92141 Clamart, France
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11
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Hasan AKMM, Fukami Y, Sato KI. Gamete membrane microdomains and their associated molecules in fertilization signaling. Mol Reprod Dev 2011; 78:814-30. [PMID: 21688335 DOI: 10.1002/mrd.21336] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2011] [Accepted: 05/15/2011] [Indexed: 12/19/2022]
Abstract
Fertilization is the fundamental system of biological reproduction in many organisms, including animals, plants, and algae. A growing body of knowledge has emerged to explain how fertilization and activation of development are accomplished. Studies on the molecular mechanisms of fertilization are in progress for a wide variety of multicellular organisms. In this review, we summarize recent findings and debates about the long-standing questions concerning fertilization: how egg and sperm become competent for their interaction with each other, how the binding and fusion of these gamete cells are made possible, and how the fertilized eggs initiate development to a newborn. We will focus on the structure and function of the membrane microdomains (MDs) of egg and sperm that may serve as a platform or signaling center for the aforementioned cellular functions. In particular, we provide evidence that MDs of eggs from the African clawed frog, Xenopus laevis, play a pivotal role in receiving extracellular signals from fertilizing sperm and then transmitting them to the egg cytoplasm, where the tyrosine kinase Src is present and responsible for the subsequent signaling events collectively called egg activation. The presence of a new signaling axis involving uroplakin III, an MD-associated transmembrane protein, and Src in this system will be highlighted and discussed.
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Affiliation(s)
- A K M Mahbub Hasan
- Laboratory of Cell Signaling and Development, Department of Molecular Biosciences, Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan
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12
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McGinnis LK, Carroll DJ, Kinsey WH. Protein tyrosine kinase signaling during oocyte maturation and fertilization. Mol Reprod Dev 2011; 78:831-45. [PMID: 21681843 DOI: 10.1002/mrd.21326] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Accepted: 04/30/2011] [Indexed: 11/11/2022]
Abstract
The oocyte is a highly specialized cell capable of accumulating and storing energy supplies as well as maternal transcripts and pre-positioned signal transduction components needed for zygotic development, undergoing meiosis under control of paracrine signals from the follicle, fusing with a single sperm during fertilization, and zygotic development. The oocyte accomplishes this diverse series of events by establishing an array of signal transduction pathway components that include a select collection of protein tyrosine kinases (PTKs) that are expressed at levels significantly higher than most other cell types. This array of PTKs includes cytosolic kinases such as SRC-family PTKs (FYN and YES), and FAK kinases, as well as FER. These kinases typically exhibit distinct patterns of localization and in some cases are translocated from one subcellular compartment to another during meiosis. Significant differences exist in the extent to which PTK-mediated pathways are used by oocytes from species that fertilize externally versus internally. The PTK activation profiles as well as calcium signaling pattern seems to correlate with the extent to which a rapid block to polyspermy is required by the biology of each species. Suppression of each of the SRC-family PTKs as well as FER kinase results in failure of meiotic maturation or zygote development, indicating that these PTKs are important for oocyte quality and developmental potential. Future studies will hopefully reveal the extent to which these factors impact clinical assisted reproductive techniques in domestic animals and humans.
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Affiliation(s)
- Lynda K McGinnis
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA.
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13
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Aarabi M, Qin Z, Xu W, Mewburn J, Oko R. Sperm-borne protein, PAWP, initiates zygotic development in Xenopus laevis by eliciting intracellular calcium release. Mol Reprod Dev 2010; 77:249-56. [PMID: 20017143 DOI: 10.1002/mrd.21140] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
We previously reported postacrosomal sheath WW domain binding protein (PAWP) as a candidate sperm borne, oocyte-activating factor. PAWP enters the oocyte during fertilization and induces oocyte activation events including meiotic resumption, pronuclear formation, and egg cleavage. However, in order to provide proof that PAWP is a primary initiator of zygotic development it is imperative to show that PAWP initiates intracellular calcium signaling, which is considered essential for oocyte activation. Utilizing Xenopus laevis as our model, we injected recombinant PAWP or Xenopus sperm into metaphase II-arrested oocytes and observed a significant rise in intracellular calcium levels over controls. Concurring intensities and durations of PAWP and sperm-induced calcium waves, detected by infrared two-photon laser-scanning fluorescence microscopy, were prevented by coinjection of a competitive PPGY-containing peptide derived from PAWP but not by the point-mutated form of this peptide. This study also correlates PAWP and sperm-induced calcium release with meiotic resumption in Xenopus. The similar mode of oocyte activation, and the ability of the competitive peptide in blocking both sperm- and PAWP-induced calcium release, provide evidence for the first time that sperm-anchored PAWP is a primary initiator of zygotic development.
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Affiliation(s)
- Mahmoud Aarabi
- Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada K7L 3N6
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14
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Townley IK, Schuyler E, Parker-Gür M, Foltz KR. Expression of multiple Src family kinases in sea urchin eggs and their function in Ca2+ release at fertilization. Dev Biol 2009; 327:465-77. [PMID: 19150445 DOI: 10.1016/j.ydbio.2008.12.032] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2008] [Revised: 12/19/2008] [Accepted: 12/22/2008] [Indexed: 01/22/2023]
Abstract
Egg activation at fertilization in deuterostomes requires a rise in intracellular Ca(2+), which is released from the egg's endoplasmic reticulum. In sea urchins, a Src Family Kinase (SpSFK1) is necessary for the PLCgamma-mediated signaling event that initiates this Ca(2+) release (Giusti, A.F., O'Neill, F.J., Yamasu, K., Foltz, K.R. and Jaffe, L.A., 2003. Function of a sea urchin egg Src family kinase in initiating Ca2+ release at fertilization. Dev. Biol. 256, 367-378.). Annotation of the Strongylocentrotus purpuratus genome sequence led to the identification of additional, predicted SFKs (Bradham, C.A., Foltz, D.R., Beane, W.S., Amone, M.I., Rizzo, F., Coffman, J.A., Mushegian, A., Goel, M., Morales, J., Geneviere, A.M., Lapraz, F., Robertson, A.J., Kelkar, H., Loza-Coll, M., Townley, I.K., Raisch, M., Roux, M.M., Lepage, T., Gache, C., McClay, D.R., Manning, G., 2006. The sea urchin kinome: a first look. Dev. Biol. 300, 180-193.; Roux, M.M., Townley, I.K., Raisch, M., Reade, A., Bradham, C., Humphreys, G., Gunaratne, H.J., Killian, C.E., Moy, G., Su, Y.H., Ettensohn, C.A., Wilt, F., Vacquier, V.D., Burke, R.D., Wessel, G. and Foltz, K.R., 2006. A functional genomic and proteomic perspective of sea urchin calcium signaling and egg activation. Dev. Biol. 300, 416-433.). Here, we describe the cloning and characterization of these 4 additional SFKs and test their function during the initial Ca(2+) release at fertilization using the dominant-interfering microinjection method coupled with Ca(2+) recording. While two of the new SFKs (SpFrk and SpSFK3) are necessary for Ca(2+) release, SpSFK5 appears dispensable for early egg to embryo transition events. Interestingly, SpSFK7 may be involved in preventing precocious release of Ca(2+). Binding studies indicate that only SpSFK1 is capable of direct interaction with PLCgamma. Immunolocalization studies suggest that one or more SpSFK and PLCgamma are localized to the egg cortex and at the site of sperm-egg interaction. Collectively, these data indicate that more than one SFK is involved in the Ca(2+) release pathway at fertilization.
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Affiliation(s)
- Ian K Townley
- Department of Molecular, Cellular and Developmental Biology and the Marine Science Institute, UC Santa Barbara Santa Barbara, CA 93106-9610, USA.
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15
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Abstract
The onset of development in most species studied is triggered by one of the largest and longest calcium transients known to us. It is the most studied and best understood aspect of the calcium signals that accompany and control development. Its properties and mechanisms demonstrate what embryos are capable of and thus how the less-understood calcium signals later in development may be generated. The downstream targets of the fertilization calcium signal have also been identified, providing some pointers to the probable targets of calcium signals further on in the process of development. In one species or another, the fertilization calcium signal involves all the known calcium-releasing second messengers and many of the known calcium-signalling mechanisms. These calcium signals also usually take the form of a propagating calcium wave or waves. Fertilization causes the cell cycle to resume, and therefore fertilization signals are cell-cycle signals. In some early embryonic cell cycles, calcium signals also control the progress through each cell cycle, controlling mitosis. Studies of these early embryonic calcium-signalling mechanisms provide a background to the calcium-signalling events discussed in the articles in this issue.
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Affiliation(s)
- Michael Whitaker
- Institute of Cell and Molecular Biology, Newcastle University Medical School, Framlington Place, Newcastle upon Tyne NE2 4HH, UK.
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Malcuit C, Fissore RA. Activation of fertilized and nuclear transfer eggs. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2007; 591:117-31. [PMID: 17176559 DOI: 10.1007/978-0-387-37754-4_9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
In all animal species, initiation of embryonic development occurs shortly after the joining together of the gametes from each of the sexes. The first of these steps, referred to as "egg activation", is a series of molecular events that results in the syngamy of the two haploid genomes and the beginning of cellular divisions for the new diploid embryo. For many years it has been known that the incoming sperm drives this process, as an unfertilized egg will remain dormant until it can no longer sustain normal metabolic processes. Until recently, it was also believed that the sperm was the only cell capable of creating a viable embryo and offspring. Recent advances in cell biology have allowed researchers to not only understand the molecular mechanisms of egg activation, but to exploit the use of pharmacological agents to bypass sperm-induced egg activation for the creation of animals by somatic cell nuclear transfer. This chapter will focus on the molecular events of egg activation in mammals as they take place during fertilization, and will discuss how these mechanisms are successfully bypassed in processes such as somatic cell nuclear transfer.
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Affiliation(s)
- Christopher Malcuit
- Department of Veterinary and Animal Sciences, Paige Laboratory, University of Massachusetts, Amherst, Massachusetts 01003, USA
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17
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Abstract
Fertilization in all species studied to date induces an increase in the intracellular concentration of free calcium ions ([Ca2+]i) within the egg. In mammals, this [Ca2+]i signal is delivered in the form of long-lasting [Ca2+]i oscillations that begin shortly after fusion of the gametes and persist beyond the time of completion of meiosis. While not fully elucidated, recent evidence supports the notion that the sperm delivers into the ooplasm a trigger of oscillations, the so-called sperm factor (SF). The recent discovery that mammalian sperm harbor a specific phospholipase C (PLC), PLCzeta has consolidated this view. The fertilizing sperm, and presumably PLCzeta promote Ca2+ release in eggs via the production of inositol 1,4,5-trisphosphate (IP3), which binds and gates its receptor, the type-1 IP3 receptor, located on the endoplasmic reticulum, the Ca2+ store of the cell. Repetitive Ca2+ release in this manner results in a positive cumulative effect on downstream signaling molecules that are responsible for the completion of all the events comprising egg activation. This review will discuss recent advances in our understanding of how [Ca2+]i oscillations are initiated and regulated in mammals, highlight areas of discrepancies, and emphasize the need to better characterize the downstream molecular cascades that are dependent on [Ca2+]i oscillations and that may impact embryo development.
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Affiliation(s)
- Christopher Malcuit
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
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18
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Geraci F, Giudice G. Mechanisms of Ca2+ liberation at fertilization. Biochem Biophys Res Commun 2005; 335:265-9. [PMID: 16023615 DOI: 10.1016/j.bbrc.2005.06.103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2005] [Accepted: 06/21/2005] [Indexed: 11/25/2022]
Abstract
The mechanisms underlying the Ca2+ release at fertilization of several animal organisms are reported. Four main classical theories are described, i.e., that of Ca2+ release following simple sperm contact and a G protein stimulation; that of simple sperm contact followed by a tyrosine kinase receptor activation; that of the necessity of introduction by sperm into the egg of molecules for Ca2+ release; and that the molecule introduced into the marine eggs for Ca2+ release is the same Ca2+. Two other mechanisms for Ca2+ release are also illustrated: that of ryanodine receptor stimulation and that of NAADP formation.
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Affiliation(s)
- Fabiana Geraci
- Dipartimento di Biologia Cellulare e dello Sviluppo, Università di Palermo, Italy
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19
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Mahbub Hasan AKM, Sato KI, Sakakibara K, Ou Z, Iwasaki T, Ueda Y, Fukami Y. Uroplakin III, a novel Src substrate in Xenopus egg rafts, is a target for sperm protease essential for fertilization. Dev Biol 2005; 286:483-92. [PMID: 16168405 DOI: 10.1016/j.ydbio.2005.08.020] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2005] [Revised: 08/05/2005] [Accepted: 08/12/2005] [Indexed: 10/25/2022]
Abstract
In a previous study, we identified Xenopus egg uroplakin III (xUPIII), a single-transmembrane protein that localized to lipid/membrane rafts and was tyrosine-phosphorylated upon fertilization. An antibody against the xUPIII extracellular domain abolishes fertilization, suggesting that xUPIII acts not only as tyrosine kinase substrate but also as a receptor for sperm. Previously, it has been shown that the protease cathepsin B can promote a transient Ca2+ release and egg activation as seen in fertilized eggs (Mizote, A., Okamoto, S., Iwao, Y., 1999. Activation of Xenopus eggs by proteases: possible involvement of a sperm protease in fertilization. Dev. Biol. 208, 79-92). Here, we show that activation of Xenopus eggs by cathepsin B is accompanied by tyrosine phosphorylation of egg-raft-associated Src, phospholipase Cgamma, and xUPIII. Cathepsin B also promotes a partial digestion of xUPIII both in vitro and in vivo. A synthetic xUPIII-GRR peptide, which contains a potential proteolytic site, inhibits the cathepsin-B-mediated proteolysis and tyrosine phosphorylation of xUPIII and egg activation. Importantly, this peptide also inhibits sperm-induced tyrosine phosphorylation of xUPIII and egg activation. Protease activity that digests xUPIII in an xUPIII-GRR peptide-sensitive manner is present in Xenopus sperm. Several protease inhibitors, which have been identified to be inhibitory toward Xenopus fertilization, are shown to inhibit sperm-induced tyrosine phosphorylation of xUPIII. Uroplakin Ib, a tetraspanin UP member, is found to be associated with xUPIII in egg rafts. Our results highlight novel mechanisms of fertilization signaling by which xUPIII serves as a potential target for sperm protease essential for fertilization.
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Affiliation(s)
- A K M Mahbub Hasan
- Graduate School of Science and Technology, Kobe University, Kobe 657-8501, Japan
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O'Neill FJ, Gillett J, Foltz KR. Distinct roles for multiple Src family kinases at fertilization. J Cell Sci 2005; 117:6227-38. [PMID: 15564383 DOI: 10.1242/jcs.01547] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Egg activation at fertilization requires the release of Ca2+ from the endoplasmic reticulum of the egg. Recent evidence indicates that Src family kinases (SFKs) function in the signaling pathway that initiates this Ca2+ release in the eggs of many deuterostomes. We have identified three SFKs expressed in starfish (Asterina miniata) eggs, designated AmSFK1, AmSFK2 and AmSFK3. Antibodies made against the unique domains of each AmSFK protein revealed that all three are expressed in eggs and localized primarily to the membrane fraction. Both AmSFK1 and AmSFK3 (but not AmSFK2) are necessary for egg activation, as determined by injection of starfish oocytes with dominant-interfering Src homology 2 (SH2) domains, which specifically delay and reduce the initial release of Ca2+ at fertilization. AmSFK3 exhibits a very rapid and transient kinase activity in response to fertilization, peaking at 30 seconds post sperm addition. AmSFK1 kinase activity also increases transiently at fertilization, but peaks later, at 2 minutes. These results indicate that there are multiple SFKs present in starfish eggs with distinct, perhaps sequential, signaling roles.
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Affiliation(s)
- Forest J O'Neill
- Department of Molecular, Cellular and Developmental Biology and the Marine Science Institute, University of California, Santa Barbara, CA 93106-9610, USA
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21
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Mehlmann LM, Jaffe LA. SH2 domain-mediated activation of an SRC family kinase is not required to initiate Ca2+ release at fertilization in mouse eggs. Reproduction 2005; 129:557-64. [PMID: 15855619 DOI: 10.1530/rep.1.00638] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
SRC family kinases (SFKs) function in initiating Ca2+release at fertilization in several species in the vertebrate evolutionary line, but whether they play a similar role in mammalian fertilization has been uncertain. We investigated this question by first determining which SFK proteins are expressed in mouse eggs, and then measuring Ca2+release at fertilization in the presence of dominant negative inhibitors. FYN and YES proteins were found in mouse eggs, but other SFKs were not detected; based on this, we injected mouse eggs with a mixture of FYN and YES Src homology 2 (SH2) domains. These SH2 domains were effective inhibitors of Ca2+release at fertilization in starfish eggs, but did not inhibit Ca2+release at fertilization in mouse eggs. Thus the mechanism by which sperm initiate Ca2+release in mouse eggs does not depend on SH2 domain-mediated activation of an SFK. We also tested the small molecule SFK inhibitor SU6656, and found that it became compartmentalized in the egg cytoplasm, thus suggesting caution in the use of this inhibitor. Our findings indicate that although the initiation of Ca2+release at fertilization of mammalian eggs occurs by a pathway that has many similarities to that in evolutionarily earlier animal groups, the requirement for SH2 domain-mediated activation of an SFK is not conserved.
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Affiliation(s)
- Lisa M Mehlmann
- Department of Cell Biology, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, Connecticut 06032, USA.
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22
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Talmor-Cohen A, Tomashov-Matar R, Eliyahu E, Shapiro R, Shalgi R. Are Src family kinases involved in cell cycle resumption in rat eggs? Reproduction 2004; 127:455-63. [PMID: 15047936 DOI: 10.1530/rep.1.00104] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The earliest visible indications for the transition to embryos in mammalian eggs, known as egg activation, are cortical granules exocytosis (CGE) and resumption of meiosis (RM); these events are triggered by the fertilizing spermatozoon through a series of Ca2+ transients. The pathways, within the egg, leading to the intracellular Ca2+ release and to the downstream cellular events, are currently under intensive investigation. The involvement of Src family kinases (SFKs) in Ca2+ release at fertilization is well supported in marine invertebrate eggs but not in mammalian eggs. In a previous study we have shown the expression and localization of Fyn, the first SFK member demonstrated in the mammalian egg. The purpose of the current study was to identify other common SFKs and resolve their function during activation of mammalian eggs. All three kinases examined: Fyn, c-Src and c-Yes are distributed throughout the egg cytoplasm. However, Fyn and c-Yes tend to concentrate at the egg cortex, though only Fyn is localized to the spindle as well. The different localizations of the various SFKs imply the possibility of their different functions within the egg. To examine whether SFKs participate in the signal transduction pathways during egg activation, we employed selective inhibitors of the SFKs activity (PP2 and SU6656). The results demonstrate that RM, which is triggered by Ca2+ elevation, is an SFK-dependent process, while CGE, triggered by either Ca2+ elevation or protein kinase C (PKC), is not. The possible involvement of SFKs in the signal transduction pathways that lead from the sperm-egg fusion site downstream of the Ca2+ release remains unclear.
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Affiliation(s)
- A Talmor-Cohen
- Department of Cell and Developmental Biology, Sackler Faculty of Medicine, Tel Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
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23
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Runft LL, Carroll DJ, Gillett J, Giusti AF, O'Neill FJ, Foltz KR. Identification of a starfish egg PLC-gamma that regulates Ca2+ release at fertilization. Dev Biol 2004; 269:220-36. [PMID: 15081369 DOI: 10.1016/j.ydbio.2004.01.031] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2003] [Revised: 01/23/2004] [Accepted: 01/27/2004] [Indexed: 10/26/2022]
Abstract
At fertilization, eggs undergo a cytoplasmic free Ca2+ rise, which is necessary for stimulating embryogenesis. In starfish eggs, studies using inhibitors designed against vertebrate proteins have shown that this Ca2+ rise requires an egg Src family kinase (SFK) that directly or indirectly activates phospholipase C-gamma (PLC-gamma) to produce IP3, which triggers Ca2+ release from the egg's endoplasmic reticulum (ER) [reviewed in Semin. Cell Dev. Biol. 12 (2001) 45]. To examine in more detail the endogenous factors in starfish eggs that are required for Ca2+ release at fertilization, an oocyte cDNA encoding PLC-gamma was isolated from the starfish Asterina miniata. This cDNA, designated AmPLC-gamma, encodes a protein with 49% identity to mammalian PLC-gamma1. A 58-kDa Src family kinase interacted with recombinant AmPLC-gamma Src homology 2 (SH2) domains in a specific, fertilization-responsive manner. Immunoprecipitations of sea urchin egg PLC-gamma using an affinity-purified antibody directed against AmPLC-gamma revealed fertilization-dependent phosphorylation of PLC-gamma. Injecting starfish eggs with the tandem SH2 domains of AmPLC-gamma (which inhibits PLC-gamma activation) specifically inhibited Ca2+ release at fertilization. These results indicate that an endogenous starfish egg PLC-gamma interacts with an egg SFK and mediates Ca2+ release at fertilization via a PLC-gamma SH2 domain-mediated mechanism.
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Affiliation(s)
- Linda L Runft
- Department of Molecular, Cellular & Developmental Biology and the Marine Science Institute, University of California-Santa Barbara, Santa Barbara, CA 93106-9610, USA
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24
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Sato KI, Iwasaki T, Hirahara S, Nishihira Y, Fukami Y. Molecular dissection of egg fertilization signaling with the aid of tyrosine kinase-specific inhibitor and activator strategies. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2004; 1697:103-21. [PMID: 15023354 DOI: 10.1016/j.bbapap.2003.11.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2003] [Accepted: 11/12/2003] [Indexed: 11/28/2022]
Abstract
Fertilization is triggered by sperm-egg interaction and fusion that initiate a transient rise(s) in the free intracellular calcium ([Ca(2+)](i)) that is responsible for a series of biochemical and cell biological events, so-called "egg activation". Calcium-dependent egg activation leads to the initiation of developmental program that culminates in the birth of individuals. A growing body of knowledge has uncovered the molecular mechanisms underlying sperm-induced transient [Ca(2+)](i) increase(s) to some extent; namely, in most animals so far studied, a second messenger inositol 1,4,5-trisphosphate (IP(3)) seems to play a pivotal role in inducing [Ca(2+)](i) transient(s) at fertilization. However, signaling mechanisms used by sperm to initiate IP(3)-[Ca(2+)](i) transient pathway have not been elucidated. To approach this problem, we have employed African clawed frog, Xenopus laevis, as a model animal and conducted experiments designed specifically to determine the role of the Src family protein-tyrosine kinases (SFKs or Src family PTKs) in the sperm-induced egg activation. This review compiles information about the use of PTK-specific inhibitors and activators for analyzing signal transduction events in egg fertilization. Specifically, we focus on molecular identification of Xenopus Src and the signaling mechanism of the Src-dependent egg activation that has been established recently. We also summarize recent advances in understanding the role of the Src family kinases in egg fertilization of other model organisms, and discuss future directions of the field.
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Affiliation(s)
- Ken-ichi Sato
- Research Center for Environmental Genomics, Kobe University, 1-1 Rokkodai-cho, Nada, Kobe 657-8501, Japan
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25
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Kinsey WH, Wu W, Macgregor E. Activation of Src-family PTK activity at fertilization: role of the SH2 domain. Dev Biol 2003; 264:255-62. [PMID: 14623246 DOI: 10.1016/j.ydbio.2003.08.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The role of Src-family protein tyrosine kinases (SFKs) in egg activation has been established, in large part, by the observation that GST fusion proteins encoding the SH2 domain of Src or Fyn suppress the sperm-induced calcium transient and cause polyspermy in marine invertebrate eggs. These fusion proteins are thought to act as dominant-negative inhibitors of SFK function; however, the mechanism by which they work is not known. The objective of the present study was to test the hypothesis that fusion proteins containing the above SH2 domains prevent activation of SFKs in response to fertilization. A single cell assay was developed that allows estimation of SFK activity in eggs injected with the GST-Fyn-SH2 fusion protein. The results demonstrate that the GST-Fyn-SH2 fusion protein prevents fertilization induced stimulation of SFK activity at concentrations that also suppress the sperm-induced calcium transient in zebrafish eggs.
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Affiliation(s)
- William H Kinsey
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, KS 66160, USA.
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26
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Giusti AF, O'Neill FJ, Yamasu K, Foltz KR, Jaffe LA. Function of a sea urchin egg Src family kinase in initiating Ca2+ release at fertilization. Dev Biol 2003; 256:367-78. [PMID: 12679109 DOI: 10.1016/s0012-1606(03)00043-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Egg activation at fertilization requires the release of Ca(2+) from the egg's endoplasmic reticulum, and recent evidence has indicated that a Src family kinase (SFK) may function in initiating this signaling pathway in echinoderm eggs. Here, we identify and characterize a SFK from the sea urchin Strongylocentrotus purpuratus, SpSFK1. SpSFK1 RNA is present in eggs, and an antibody made against a SpSFK1 peptide recognizes an approximately 58-kDa egg membrane-associated protein in eggs of S. purpuratus as well as another sea urchin Lytechinus variegatus. Injection of both species of sea urchin eggs with dominant-interfering Src homology 2 domains of SpSFK1 delays and reduces the release of Ca(2+) at fertilization. Injection of an antibody against SpSFK1 into S. purpuratus eggs also causes a small increase in the delay between sperm-egg fusion and Ca(2+) release. In contrast, when injected into eggs of L. variegatus, this same antibody has a dramatic stimulatory effect: it causes PLCgamma-dependent Ca(2+) release like that occurring at fertilization. Correspondingly, in lysates of L. variegatus eggs, but not S. purpuratus eggs, the antibody stimulates SFK activity. Injection of L. variegatus eggs with another antibody that recognizes the L. variegatus egg SFK also causes PLCgamma-dependent Ca(2+) release like that at fertilization. These results indicate that activation of a Src family kinase present in sea urchin eggs is necessary to cause Ca(2+) release at fertilization and is capable of stimulating Ca(2+) release in the unfertilized egg via PLCgamma, as at fertilization.
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Affiliation(s)
- Andrew F Giusti
- Department of Physiology, University of Connecticut Health Center, Farmington, CT 06032, USA.
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27
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Tunquist BJ, Maller JL. Under arrest: cytostatic factor (CSF)-mediated metaphase arrest in vertebrate eggs. Genes Dev 2003; 17:683-710. [PMID: 12651887 DOI: 10.1101/gad.1071303] [Citation(s) in RCA: 185] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Affiliation(s)
- Brian J Tunquist
- The Howard Hughes Medical Institute and Department of Pharmacology, University of Colorado School of Medicine, Denver, CO 80262, USA
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28
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Sette C, Paronetto MP, Barchi M, Bevilacqua A, Geremia R, Rossi P. Tr-kit-induced resumption of the cell cycle in mouse eggs requires activation of a Src-like kinase. EMBO J 2002; 21:5386-95. [PMID: 12374739 PMCID: PMC129085 DOI: 10.1093/emboj/cdf553] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Microinjection in mouse eggs of tr-kit, a truncated form of the c-kit tyrosine kinase present in mouse spermatozoa, causes resumption of meiosis through activation of phospholipase Cgamma1 (PLCgamma1) and Ca(2+) mobilization from intracellular stores. We show that the Src-like kinase Fyn phosphorylates Tyr161 in tr-kit and that this residue is essential for tr-kit function. Fyn is localized in the cortex region underneath the plasma membrane in mouse oocytes. Using several approaches, we demonstrate that Fyn associates with tr-kit and that the interaction requires Tyr161. The interaction between tr-kit and Fyn triggers activation of the kinase as monitored by both autophosphorylation and phosphorylation of PLCgamma1. Co-injection of tr-kit with the SH2 domain of Fyn, or pre-treatment with a Fyn inhibitor, impairs oocyte activation, suggesting that activation of Fyn by tr-kit also occurs in vivo. Finally, microinjection of constitutively active Fyn triggers oocyte activation downstream of tr-kit but still requires PLC activity. We suggest that the mechanism by which tr-kit triggers resumption of meiosis of mouse eggs requires a functional interaction with Fyn and phosphorylation of PLCgamma1.
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Affiliation(s)
- Claudio Sette
- Department of Public Health and Cell Biology, Section of Anatomy, University of Rome ‘Tor Vergata’, Via Montpellier 1 and
Department of Psychology, University of Rome ‘La Sapienza’, Rome, Italy Corresponding author e-mail:
| | | | | | - Arturo Bevilacqua
- Department of Public Health and Cell Biology, Section of Anatomy, University of Rome ‘Tor Vergata’, Via Montpellier 1 and
Department of Psychology, University of Rome ‘La Sapienza’, Rome, Italy Corresponding author e-mail:
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29
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Abstract
Fertilization involves the activation of Src-family protein kinases which play a role at multiple stages of the egg activation process. The objective of the present study was to determine the mechanism by which one of these kinases, the Fyn kinase, is activated in response to fertilization of the zebrafish egg. Inhibitor studies demonstrated that many aspects of egg activation, including Fyn activation, require phosphotyrosyl phosphatase activity. A phosphotyrosyl phosphatase was found to be tightly associated with Fyn kinase and this interaction was mapped to the SH2 domain of Fyn. Coimmunoprecipitation studies identified rPTPalpha as a phosphatase that is complexed with Fyn in the egg, raising the possibility that rPTPalpha is part of the regulatory mechanism responsible for activating Fyn at fertilization.
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Affiliation(s)
- Wenjun Wu
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, 66160-7400, USA
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31
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Abstract
A centrally important factor in initiating egg activation at fertilization is a rise in free Ca(2+) in the egg cytosol. In echinoderm, ascidian, and vertebrate eggs, the Ca(2+) rise occurs as a result of inositol trisphosphate-mediated release of Ca(2+) from the endoplasmic reticulum. The release of Ca(2+) at fertilization in echinoderm and ascidian eggs requires SH2 domain-mediated activation of a Src family kinase (SFK) and phospholipase C (PLC)gamma. Though some evidence indicates that a SFK and PLC may also function at fertilization in vertebrate eggs, SH2 domain-mediated activation of PLC gamma appears not to be required. Much work has focused on identifying factors from sperm that initiate egg activation at fertilization, either as a result of sperm-egg contact or sperm-egg fusion. Current evidence from studies of ascidian and mammalian fertilization favors a fusion-mediated mechanism; this is supported by experiments indicating that injection of sperm extracts into eggs causes Ca(2+) release by the same pathway as fertilization.
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Affiliation(s)
- Linda L Runft
- Department of Physiology, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
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32
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Abstract
Embryonic development is initiated after the fertilizing spermatozoon enters the egg and triggers a process known as 'egg activation'. Activation results in an increase in intracellular calcium concentration, cortical granule exocytosis (CGE), cell cycle resumption and recruitment of maternal mRNA. Various treatments can induce parthenogenetic activation characterized by the same manifestations. Signal transduction pathways similar to those known for somatic cells mediate the mammalian egg activation. This review focuses on the signal transduction pathways that occur during mammalian fertilization and during parthenogenetic egg activation. We discuss the possibility that members of the protein tyrosine kinase (PTKs) families, the Src family PTKs in particular, operate during egg activation and that protein kinase C can induce CGE.
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Affiliation(s)
- Anat Talmor-Cohen
- Department of Embryology and Teratology, Sackler Faculty of Medicine, Tel Aviv University, Ramat-Aviv 69978, Tel-Aviv, Israel
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Lim D, Kyozuka K, Gragnaniello G, Carafoli E, Santella L. NAADP+ initiates the Ca2+ response during fertilization of starfish oocytes. FASEB J 2001; 15:2257-67. [PMID: 11641253 DOI: 10.1096/fj.01-0157com] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We have explored the role of the recently discovered second messenger nicotinic acid adenine nucleotide phosphate (NAADP+) in Ca2+ swings that accompany the fertilization process in starfish oocytes. The injection of NAADP+ deep into the cytoplasm of oocytes matured by the hormone 1-methyladenine (1-MA), mobilized Ca2+ exclusively in the cortical layer, showing that the NAADP+-sensitive Ca2+ pool is restricted to the subplasma membrane region of the cell. At variance with this, InsP3 initiated the liberation of Ca2+ next to the point of injection in the center of the cell. The initial cortical Ca2+ liberation induced by NAADP+ was followed by a spreading of the Ca2+ wave to the remainder of the cell and by a massive cortical granule exocytosis similar to that routinely observed on injection of InsP3. A striking difference in the responses to NAADP+ and InsP3 was revealed by the removal of the nucleus from immature oocytes, i.e., from oocytes not treated with 1-MA. Whereas the Ca2+ response and the cortical granule exocytosis induced by NAADP+ were unaffected by the removal of the nucleus, the Ca2+ response promoted by InsP3 was significantly slowed. In addition, the cortical granule exocytosis was completely abolished. When enucleated oocytes were fertilized, the spermatozoon still promoted the Ca2+ wave and normal cortical exocytosis, strongly suggesting that the Ca2+ response was mediated by NAADP+ and not by InsP3. InsP3-sensitive Ca2+ stores may mediate the propagation of the wave initiated by NAADP+ since its spreading was strongly affected by removal of the nucleus.
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Affiliation(s)
- D Lim
- Asamushi Marine Biological Station, Asamushi, Aomori 039-3501, Japan
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34
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Belton RJ, Adams NL, Foltz KR. Isolation and characterization of sea urchin egg lipid rafts and their possible function during fertilization. Mol Reprod Dev 2001; 59:294-305. [PMID: 11424215 DOI: 10.1002/mrd.1034] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Specialized membrane microdomains called rafts are thought to play a role in many types of cell-cell interactions and signaling. We have investigated the possibility that sea urchin eggs contain these specialized membrane microdomains and if they play a role in signal transduction at fertilization. A low density, TX-100 insoluble membrane fraction, typical of lipid rafts, was isolated by equilibrium gradient centrifugation. This raft fraction contained proteins distinct from cytoskeletal complexes. The fraction was enriched in tyrosine phosphorylated proteins and contained two proteins known to be involved in signaling during egg activation (an egg Src-type kinase and PLC gamma). This fraction was further characterized as a prototypical raft fraction by the release of proteins in response to in vitro treatment of the rafts with the cholesterol binding drug, methyl-beta-cyclodextrin (M beta CD). Furthermore, treatment of eggs with M beta CD inhibited fertilization, suggesting that egg lipid rafts play a physiological role in fertilization. Mol. Reprod. Dev. 59:294-305, 2001.
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Affiliation(s)
- R J Belton
- Department of Molecular, Cellular and Developmental Biology and the Marine Science Institute, University of California Santa Barbara, Santa Barbara, California 93106, USA
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35
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Hyslop LA, Carroll M, Nixon VL, McDougall A, Jones KT. Simultaneous Measurement of Intracellular Nitric Oxide and Free Calcium Levels in Chordate Eggs Demonstrates That Nitric Oxide Has No Role at Fertilization. Dev Biol 2001; 234:216-30. [PMID: 11356031 DOI: 10.1006/dbio.2001.0252] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
At fertilization in sea urchin, the free radical nitric oxide (NO) has recently been suggested to cause the intracellular Ca(2+) rise responsible for egg activation. The authors suggested that NO could be a universal activator of eggs and the present study was set up to test this hypothesis. Intracellular NO and Ca(2+) levels were monitored simultaneously in eggs of the mouse or the urochordate ascidian Ascidiella aspersa. Eggs were either fertilized or sperm extracts microinjected. Sperm-induced Ca(2+) rises were not associated with any global, or local, change in intracellular NO, although we were able to detect NO produced by the addition of a NO donor. Furthermore, the NO synthase inhibitor N(G)-nitro-L-arginine methyl ester had no effect on sperm-induced Ca(2+) release but did block completely ionomycin-induced NO synthase activation. Therefore, we suggest that the current data provide evidence that NO has no role in the fertilization of these two chordate eggs.
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Affiliation(s)
- L A Hyslop
- Department of Physiological Sciences, The Medical School, Framlington Place, The University of Newcastle, Newcastle, NE2 4HH, England, UK
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36
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Wu H, Smyth J, Luzzi V, Fukami K, Takenawa T, Black SL, Allbritton NL, Fissore RA. Sperm factor induces intracellular free calcium oscillations by stimulating the phosphoinositide pathway. Biol Reprod 2001; 64:1338-49. [PMID: 11319137 DOI: 10.1095/biolreprod64.5.1338] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Injection of a porcine cytosolic sperm factor (SF) or of a porcine testicular extract into mammalian eggs triggers oscillations of intracellular free calcium ([Ca(2+)](i)) similar to those initiated by fertilization. To elucidate whether SF activates the phosphoinositide (PI) pathway, mouse eggs or SF were incubated with U73122, an inhibitor of events leading to phospholipase C (PLC) activation and/or of PLC itself. In both cases, U73122 blocked the ability of SF to induce [Ca(2+)](i) oscillations, although it did not inhibit Ca(2+) release caused by injection of inositol 1,4,5-triphosphate (IP(3)). The inactive analogue, U73343, had no effect on SF-induced Ca(2+) responses. To determine at the single cell level whether SF triggers IP(3) production concomitantly with a [Ca(2+)](i) rise, SF was injected into Xenopus oocytes and IP(3) concentration was determined using a biological detector cell combined with capillary electrophoresis. Injection of SF induced a significant increase in [Ca(2+)](i) and IP(3) production in these oocytes. Using ammonium sulfate precipitation, chromatographic fractionation, and Western blotting, we determined whether PLCgamma1, PLCgamma2, or PLCdelta4 and/or its splice variants, which are present in sperm and testis, are responsible for the Ca(2+) activity in the extracts. Our results revealed that active fractions do not contain PLCgamma1, PLCgamma2, or PLCdelta4 and/or its splice variants, which were present in inactive fractions. We also tested whether IP(3) could be the sensitizing stimulus of the Ca(2+)-induced Ca(2+) release mechanism, which is an important feature of fertilized and SF-injected eggs. Eggs injected with adenophostin A, an IP(3) receptor agonist, showed enhanced Ca(2+) responses to CaCl(2) injections. Thus, SF, and probably sperm, induces [Ca(2+)](i) rises by persistently stimulating IP(3) production, which in turn results in long-lasting sensitization of Ca(2+)-induced Ca(2+) release. Whether SF is itself a PLC or whether it acts upstream of the egg's PLCs remains to be elucidated.
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Affiliation(s)
- H Wu
- Molecular and Cellular Biology Program and Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst 01003, USA
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37
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Abstract
The endoplasmic reticulum is a multifunctional continuous network of membrane-enclosed sacs and tubules that extends throughout the cell. The endoplasmic reticulum is the site of protein synthesis and assembly, as well as lipid and membrane synthesis. Additionally, the endoplasmic reticulum contains calcium pumps, intraluminal calcium storage proteins, and specific calcium-releasing channels. Thus, this membrane system plays a central role in intracellular signaling through the storage and release of calcium. At fertilization, the sperm triggers a large and dramatic release of calcium from the endoplasmic reticulum, which activates the egg to begin development. The ability of the egg to fully elevate calcium depends on biochemical and structural changes during oocyte maturation. The sensitivity of the calcium-releasing system increases and the endoplasmic reticulum is reorganized during maturation of the oocyte; together, these dynamic changes place a substantial calcium storage compartment just beneath the membrane, near the site of sperm-egg fusion. Localization of the calcium store may also contribute to the long-lasting calcium oscillations that are characteristic of mammalian fertilization. Examination of the endoplasmic reticulum in living eggs is leading to a better understanding of calcium release at fertilization.
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Affiliation(s)
- D Kline
- Department of Biological Sciences, Kent State University, Ohio 44242, USA
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38
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Jaffe LA, Giusti AF, Carroll DJ, Foltz KR. Ca2+ signalling during fertilization of echinoderm eggs. Semin Cell Dev Biol 2001; 12:45-51. [PMID: 11162746 DOI: 10.1006/scdb.2000.0216] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The Ca2+ rise at fertilization of echinoderm eggs is initiated by a process requiring the sequential activation of a Src family kinase, phospholipase C gamma, and the inositol trisphosphate receptor/channel in the endoplasmic reticulum. The consequences of the Ca2+ rise include exocytosis of cortical granules, which establishes a block to polyspermy, and inactivation of MAP kinase, which functions in linking the Ca2+ rise to the reinitiation of the cell cycle.
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Affiliation(s)
- L A Jaffe
- Department of Physiology, University of Connecticut Health Center, Farmington, CT 06032,
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39
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Kinsey WH, Shen SS. Role of the Fyn kinase in calcium release during fertilization of the sea urchin egg. Dev Biol 2000; 225:253-64. [PMID: 10964479 DOI: 10.1006/dbio.2000.9830] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Protein tyrosine kinase activity has been implicated as part of the signaling mechanism leading to the sperm-induced calcium transient following fertilization. In the present study, we have tested the role of the Fyn kinase in triggering the calcium transient by microinjecting domain-specific fusion proteins encoding regions of Fyn sequence as inhibitors of Fyn function in vivo. A fusion protein encoding the SH2 domain of Fyn caused an increase in the latent period between sperm-egg fusion and the beginning of the calcium transient and reduced the amplitude of the calcium signal. A fusion protein encoding the U + SH3 domains also caused a small increase in the latent period. Microscopic examination revealed that a large percentage of eggs injected with the U+SH3 or SH2 domains became polyspermic as a result of the delayed block to polyspermy. Affinity experiments demonstrated that the U+SH3 and SH2 domains of Fyn were capable of forming a stable complex with phospholipase Cgamma from the sea urchin egg. The results suggest that the Fyn kinase participates in the signaling events leading up to the calcium transient and may directly regulate phospholipase Cgamma activity at fertilization.
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Affiliation(s)
- W H Kinsey
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas, 66160, USA
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40
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Sato K, Tokmakov AA, Iwasaki T, Fukami Y. Tyrosine kinase-dependent activation of phospholipase Cgamma is required for calcium transient in Xenopus egg fertilization. Dev Biol 2000; 224:453-69. [PMID: 10926780 DOI: 10.1006/dbio.2000.9782] [Citation(s) in RCA: 108] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In a previous study (K.-I. Sato et al., 1999, Dev. Biol. 209, 308-320), we presented evidence that a Src-related protein-tyrosine kinase (PTK), named Xyk, may act upstream of the calcium release in fertilization of the Xenopus egg. In the present study, we examined whether PTK activation of phospholipase Cgamma (PLCgamma) plays a role in the fertilization-induced calcium signaling. Immunoprecipitation studies show that Xenopus egg PLCgamma is tyrosine phosphorylated and activated within a few minutes after fertilization but not after A23187-induced egg activation. Consistently, we observed a fertilization-induced association of PLCgamma with Xyk activity that was not seen in A23187-activated eggs. A Src-specific PTK inhibitor, PP1, blocked effectively the fertilization-induced association of PLCgamma with Xyk activity and up-regulation of PLCgamma, when microinjected into the egg. In addition, a PLC inhibitor, U-73122, inhibited sperm-induced inositol 1,4,5-trisphosphate production and the calcium transient and subsequent calcium-dependent events such as cortical contraction, elevation of fertilization envelope, and tyrosine dephosphorylation of p42 MAP kinase, all of which were also inhibited by PP1. On the other hand, A23187 could cause the calcium response and calcium-dependent events in eggs injected with PP1 or U-73122. These results support the idea that Xenopus egg fertilization requires Src-family PTK-dependent PLCgamma activity that acts upstream of the calcium-dependent signaling pathway.
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Affiliation(s)
- K Sato
- Laboratory of Molecular Biology, Biosignal Research Center, Kobe University, Nada, Japan.
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41
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Kuo RC, Baxter GT, Thompson SH, Stricker SA, Patton C, Bonaventura J, Epel D. NO is necessary and sufficient for egg activation at fertilization. Nature 2000; 406:633-6. [PMID: 10949304 DOI: 10.1038/35020577] [Citation(s) in RCA: 117] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The early steps that lead to the rise in calcium and egg activation at fertilization are unknown but of great interest--particularly with the advent of in vitro fertilization techniques for treating male infertility and whole-animal cloning by nuclear transfer. This calcium rise is required for egg activation and the subsequent events of development in eggs of all species. Injection of intact sperm or sperm extracts can activate eggs, suggesting that sperm-derived factors may be involved. Here we show that nitric oxide synthase is present at high concentration and active in sperm after activation by the acrosome reaction. An increase in nitrosation within eggs is evident seconds after insemination and precedes the calcium pulse of fertilization. Microinjection of nitric oxide donors or recombinant nitric oxide synthase recapitulates events of egg activation, whereas prior injection of oxyhaemoglobin, a physiological nitric oxide scavenger, prevents egg activation after fertilization. We conclude that nitric oxide synthase and nitric-oxide-related bioactivity satisfy the primary criteria of an egg activator: they are present in an appropriate place, active at an appropriate time, and are necessary and sufficient for successful fertilization.
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Affiliation(s)
- R C Kuo
- Neurosciences Program, Stanford University School of Medicine, Stanford University, California 94305, USA
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42
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Runft LL, Jaffe LA. Sperm extract injection into ascidian eggs signals Ca(2+) release by the same pathway as fertilization. Development 2000; 127:3227-36. [PMID: 10887079 DOI: 10.1242/dev.127.15.3227] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Injection of eggs of various species with an extract of sperm cytoplasm stimulates intracellular Ca(2+) release that is spatially and temporally like that occurring at fertilization, suggesting that Ca(2+) release at fertilization may be initiated by a soluble factor from the sperm. Here we investigate whether the signalling pathway that leads to Ca(2+) release in response to sperm extract injection requires the same signal transduction molecules as are required at fertilization. Eggs of the ascidian Ciona intestinalis were injected with the Src-homology 2 domains of phospholipase C gamma or of the Src family kinase Fyn (which act as specific dominant negative inhibitors of the activation of these enzymes), and the effects on Ca(2+) release at fertilization or in response to injection of a sperm extract were compared. Our findings indicate that both fertilization and sperm extract injection initiate Ca(2+) release by a pathway requiring phospholipase C gamma and a Src family kinase. These results support the hypothesis that, in ascidians, a soluble factor from the sperm cytoplasm initiates Ca(2+) release at fertilization, and indicate that the activating factor from the sperm may be a regulator, directly or indirectly, of a Src family kinase in the egg.
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Affiliation(s)
- L L Runft
- Department of Physiology, University of Connecticut Health Center, Farmington, CT 06032, USA
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43
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Giusti AF, Xu W, Hinkle B, Terasaki M, Jaffe LA. Evidence that fertilization activates starfish eggs by sequential activation of a Src-like kinase and phospholipase cgamma. J Biol Chem 2000; 275:16788-94. [PMID: 10747984 DOI: 10.1074/jbc.m001091200] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Recent evidence has indicated a requirement for a Src family kinase in initiating Ca(2+) release at fertilization in starfish eggs (Giusti, A. F., Carroll, D. J., Abassi, Y. A., Terasaki, M., Foltz, K. R., and Jaffe, L. A. (1999) J. Biol. Chem. 274, 29318-29322). We now show that injection of Src protein into starfish eggs initiates Ca(2+) release and DNA synthesis, as occur at fertilization. These responses depend on the phosphorylation state of the Src protein; only the kinase active form is effective. Like Ca(2+) release at fertilization, the Ca(2+) release in response to Src protein injection is inhibited by prior injection of the SH2 domains of phospholipase Cgamma. These findings support the conclusion that in starfish, sperm-egg interaction causes egg activation by sequential activation of a Src-like kinase and phospholipase Cgamma. Injection of the SH2 domain of Src, which inhibits Ca(2+) release at fertilization, does not inhibit Ca(2+) release caused by Src protein injection. This indicates that the requirement for a Src SH2 domain interaction is upstream of Src activation in the pathway leading to Ca(2+) release at fertilization.
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Affiliation(s)
- A F Giusti
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543, the Department of Physiology, University of Connecticut Health Center, Farmington, Connecticut 06032, USA
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44
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Sato K, Tokmakov AA, Fukami Y. Fertilization signalling and protein-tyrosine kinases. Comp Biochem Physiol B Biochem Mol Biol 2000; 126:129-48. [PMID: 10874161 DOI: 10.1016/s0305-0491(00)00192-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Fertilization is initiated by species-specific gamete cell recognition, i.e. sperm-egg interaction, followed by a rapid and sustained activation of multiple cellular and biochemical events, collectively called 'egg activation', which is indispensable for successful formation of zygotic nucleus and later embryogenesis. It is well known that sperm-induced egg activation is mediated by a transient release of calcium ions that originates from the sperm entry point and propagates through the entire egg cytoplasm. It is unclear, however, what kind of upstream events prelude to the calcium transient after sperm-egg interaction. Recently, much attention has been paid to the role of protein-tyrosine phosphorylation in egg activation process by a number of studies on some well-established model organisms. These includes marine invertebrates, frogs, and mammals. In this review, we will summarize the recent findings that begin to uncover a 'missing link' between sperm-egg interaction and egg activation with emphasis on the role of egg protein-tyrosine kinases (PTKs) in Xenopus egg fertilization.
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Affiliation(s)
- K Sato
- Laboratory of Molecular Biology, Biosignal Research Center, Kobe University, Nada, Japan.
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45
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Abassi YA, Carroll DJ, Giusti AF, Belton RJ, Foltz KR. Evidence that Src-type tyrosine kinase activity is necessary for initiation of calcium release at fertilization in sea urchin eggs. Dev Biol 2000; 218:206-19. [PMID: 10656764 DOI: 10.1006/dbio.1999.9582] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The initiation of Ca(2+) release from internal stores in the egg is a hallmark of egg activation. In sea urchins, PLCgamma activity is necessary for the production of IP(3), which leads to the initial rise in Ca(2+). To examine the possible function of a tyrosine kinase in activating PLCgamma at fertilization, sea urchin eggs were treated with the specific Src kinase inhibitor PP1 or microinjected with recombinant Src-family SH2-domain proteins, which act as dominant interfering inhibitors of Src-family kinase function. Both modes of inhibiting Src-family kinases resulted in a specific and dose-dependent delay in the onset of Ca(2+) release from the endoplasmic reticulum at fertilization. The rise in cytoplasmic pH at fertilization also was inhibited by microinjection of Src-family SH2-domain proteins. Further, an antibody directed against Src-type kinases recognized a protein of ca. M(r) 57K that was enriched in the membrane fraction of eggs. The kinase activity of this protein was stimulated rapidly and transiently at fertilization, as measured by autophosphorylation and by phosphorylation of an exogenous substrate. Together, these data indicate that a Src-type tyrosine kinase is necessary for the initiation of Ca(2+) release from the egg ER at fertilization and identify a Src-type p57 protein as a candidate in the signaling pathway leading to this Ca(2+) release.
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Affiliation(s)
- Y A Abassi
- Department of Molecular, Cellular and Developmental Biology and the Marine Science Institute, University of California at Santa Barbara, Santa Barbara, California 93106, USA
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46
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Perry AC, Wakayama T, Cooke IM, Yanagimachi R. Mammalian oocyte activation by the synergistic action of discrete sperm head components: induction of calcium transients and involvement of proteolysis. Dev Biol 2000; 217:386-93. [PMID: 10625562 DOI: 10.1006/dbio.1999.9552] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Sperm-borne oocyte-activating factor (SOAF) elicits activation sufficient for full development and originates from sperm head submembrane matrices. SOAF comprises discrete, heat-sensitive and -stable components (referred to here respectively as SOAF-I and -II) which are each necessary but not sufficient to activate oocytes. The heat-sensitive SOAF component, SOAF-I(m), becomes solubilized from the perinuclear matrix under reducing conditions (the SOAF transition) to generate SOAF-I(s). Although calcium transients likely play an important role in oocyte activation at fertilization, the question is open as to whether demembranated heads or SOAF-I(s) and/or SOAF-II can induce calcium transients. We now report that injection of demembranated sperm heads into mouse oocytes efficiently induced Ca(2+) oscillations. When injected independently, SOAF-I(s) and demembranated heads heated to 48 degrees C failed to generate Ca(2+) oscillations. However, co-injection of SOAF-I(s) and 48 degrees C-heated heads induced oscillations, mirroring their synergistic ability to activate oocytes. This suggests that SOAF-mediated activation proceeds via pathways resembling those at fertilization and provides the first direct evidence that multiple sperm components are required to induce Ca(2+) oscillations. We probed the SOAF-I(s) liberation at the center of this activation and show that in vitro it was sensitive to a profile of serine protease inhibitors. These findings support a model in which mammalian oocyte activation, including the induction of calcium transients, involves proteolytic processing of SOAF from sperm head submembrane compartments.
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Affiliation(s)
- A C Perry
- Laboratory of Vertebrate Developmental Neurogenetics, Rockefeller University, 1230 York Avenue, New York, New York, 10021-6399, USA.
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47
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Abstract
A ubiquitous signaling event in hormonal responses is the phospholipase C (PLC)-catalyzed hydrolysis of phosphatidylinositol 4, 5-bisphosphate to produce the metabolite second messenger molecules inositol 1,4,5-trisphosphate and diacylglycerol. The former provokes a transient increase in intracellular free Ca(2+), while the latter serves as a direct activator of protein kinase C. In tyrosine kinase-dependent signaling pathways this reaction is mediated by the PLC-gamma isozymes. These are direct substrates of many tyrosine kinases in a wide variety of cell types. The mechanism of PLC-gamma activation involves its association with and phosphorylation by receptor and non-receptor tyrosine kinases, as well as interaction with specialized adaptor molecules and, perhaps, other second messenger molecules. However, the biochemistry of PLC-gamma is at a more advanced state than a clear understanding of exactly how this signaling element functions in the generation of a mitogenic response.
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Affiliation(s)
- G Carpenter
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, 37232-0146, USA.
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48
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Rongish BJ, Wu W, Kinsey WH. Fertilization-induced activation of phospholipase C in the sea urchin egg. Dev Biol 1999; 215:147-54. [PMID: 10545226 DOI: 10.1006/dbio.1999.9472] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Fertilization results in the biphasic activation of polyphosphoinositide-specific phospholipase C (PLC) activity with an initial increase in activity coincident with the sperm-induced calcium transient, followed by a more sustained increase prior to mitosis. Immunoprecipitation studies demonstrated that the gamma isoform of PLC is present in both the unfertilized and the fertilized egg and contributes to the initial phase of PLC activation. Fertilization also resulted in translocation of a significant fraction of PLC-gamma from the cytosol to the membrane compartment of the egg.
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Affiliation(s)
- B J Rongish
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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49
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Giusti AF, Carroll DJ, Abassi YA, Terasaki M, Foltz KR, Jaffe LA. Requirement of a Src family kinase for initiating calcium release at fertilization in starfish eggs. J Biol Chem 1999; 274:29318-22. [PMID: 10506191 DOI: 10.1074/jbc.274.41.29318] [Citation(s) in RCA: 76] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Signal transduction leading to calcium release in echinoderm eggs at fertilization requires phospholipase Cgamma-mediated production of inositol trisphosphate (IP(3)), indicating that a tyrosine kinase is a likely upstream regulator. Because previous work has shown a fertilization-dependent association between the Src homology 2 (SH2) domains of phospholipase Cgamma and a Src family kinase, we examined whether a Src family kinase was required for Ca(2+) release at fertilization. To inhibit the function of kinases in this family, we injected starfish eggs with the SH2 domains of Src and Fyn kinases. This inhibited Ca(2+) release in response to fertilization but not in response to injection of IP(3). We further established the specificity of the inhibition by showing that the SH2 domains of several other tyrosine kinases (Abl, Syk, and ZAP-70), and the SH3 domain of Src, were not inhibitory. Also, a point-mutated Src SH2 domain, which has reduced affinity for phosphotyrosine, was a correspondingly less effective inhibitor of fertilization-induced Ca(2+) release. These results indicate that a Src family kinase, by way of its SH2 domain, links sperm-egg interaction to IP(3)-mediated Ca(2+) release at fertilization in starfish eggs.
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Affiliation(s)
- A F Giusti
- Marine Biological Laboratory, Woods Hole, Massachusetts 02543, USA
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