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Saleh A, Thanassoulas A, Aliyev E, Swann K, Naija A, Yalcin HC, Lai FA, Nomikos M. Development of Recombinant PLC-Zeta Protein as a Therapeutic Intervention for the Clinical Treatment of Oocyte Activation Failure. Biomedicines 2024; 12:1183. [PMID: 38927390 PMCID: PMC11201047 DOI: 10.3390/biomedicines12061183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Revised: 04/30/2024] [Accepted: 05/01/2024] [Indexed: 06/28/2024] Open
Abstract
The sperm-specific phospholipase C zeta (PLCζ) protein is widely considered as the predominant physiological stimulus for initiating the Ca2+ release responsible for oocyte activation during mammalian fertilization. The increasing number of genetic and clinical reports that directly link PLCζ defects and/or deficiencies with oocyte activation failure (OAF) necessitates the use of a powerful therapeutic intervention to overcome such cases of male factor infertility. Currently, in vitro fertilization (IVF) clinics treat OAF cases after intracytoplasmic sperm injection (ICSI) with Ca2+ ionophores. Despite their successful use, such chemical agents are unable to trigger the physiological pattern of Ca2+ oscillations. Moreover, the safety of these ionophores is not yet fully established. We have previously demonstrated that recombinant PLCζ protein can be successfully used to rescue failed oocyte activation, resulting in efficient blastocyst formation. Herein, we produced a maltose binding protein (MBP)-tagged recombinant human PLCζ protein capable of inducing Ca2+ oscillations in mouse oocytes similar to those observed at fertilization. Circular dichroism (CD) experiments revealed a stable, well-folded protein with a high helical content. Moreover, the recombinant protein could retain its enzymatic properties for at least up to 90 days after storage at -80 °C. Finally, a chick embryo model was employed and revealed that exposure of fertilized chicken eggs to MBP-PLCζ did not alter the embryonic viability when compared to the control, giving a first indication of its safety. Our data support the potential use of the MBP-PLCζ recombinant protein as an effective therapeutic tool but further studies are required prior to its use in a clinical setting.
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Affiliation(s)
- Alaaeldin Saleh
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha 2713, Qatar
| | - Angelos Thanassoulas
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha 2713, Qatar
| | - Elnur Aliyev
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - Karl Swann
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - Azza Naija
- Biomedical Research Center, Qatar University, Doha 2713, Qatar (H.C.Y.)
| | - Huseyin C. Yalcin
- Biomedical Research Center, Qatar University, Doha 2713, Qatar (H.C.Y.)
- Department of Biomedical Sciences, College of Health Sciences, QU Health, Qatar University, Doha 2713, Qatar
| | - F. Anthony Lai
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha 2713, Qatar
- School of Biosciences, Cardiff University, Cardiff CF10 3AX, UK
| | - Michail Nomikos
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha 2713, Qatar
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Gonzalez-Castro RA, Carnevale EM. Phospholipase C Zeta 1 (PLCZ1): The Function and Potential for Fertility Assessment and In Vitro Embryo Production in Cattle and Horses. Vet Sci 2023; 10:698. [PMID: 38133249 PMCID: PMC10747197 DOI: 10.3390/vetsci10120698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 12/01/2023] [Accepted: 12/05/2023] [Indexed: 12/23/2023] Open
Abstract
Phospholipase C Zeta 1 (PLCZ1) is considered a major sperm-borne oocyte activation factor. After gamete fusion, PLCZ1 triggers calcium oscillations in the oocyte, resulting in oocyte activation. In assisted fertilization, oocyte activation failure is a major cause of low fertility. Most cases of oocyte activation failures in humans related to male infertility are associated with gene mutations and/or altered PLCZ1. Consequently, PLCZ1 evaluation could be an effective diagnostic marker and predictor of sperm fertilizing potential for in vivo and in vitro embryo production. The characterization of PLCZ1 has been principally investigated in men and mice, with less known about the PLCZ1 impact on assisted reproduction in other species, such as cattle and horses. In horses, sperm PLCZ1 varies among stallions, and sperm populations with high PLCZ1 are associated with cleavage after intracytoplasmic sperm injection (ICSI). In contrast, bull sperm is less able to initiate calcium oscillations and undergo nuclear remodeling, resulting in poor cleavage after ICSI. Advantageously, injections of PLCZ1 are able to rescue oocyte failure in mouse oocytes after ICSI, promoting full development and birth. However, further research is needed to optimize PLCZ1 diagnostic tests for consistent association with fertility and to determine whether PLCZ1 as an oocyte-activating treatment is a physiological, efficient, and safe method for improving assisted fertilization in cattle and horses.
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Affiliation(s)
| | - Elaine M. Carnevale
- Equine Reproduction Laboratory, Department of Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA;
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Moqadam M, Tubiana T, Moutoussamy EE, Reuter N. Membrane models for molecular simulations of peripheral membrane proteins. ADVANCES IN PHYSICS: X 2021. [DOI: 10.1080/23746149.2021.1932589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Affiliation(s)
- Mahmoud Moqadam
- Department of Chemistry, University of Bergen, Bergen, Norway
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Thibault Tubiana
- Department of Chemistry, University of Bergen, Bergen, Norway
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
| | - Emmanuel E. Moutoussamy
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
- Department of Biological Sciences, University of Bergen, Bergen, Norway
| | - Nathalie Reuter
- Department of Chemistry, University of Bergen, Bergen, Norway
- Computational Biology Unit, Department of Informatics, University of Bergen, Bergen, Norway
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Katan M, Cockcroft S. Phospholipase C families: Common themes and versatility in physiology and pathology. Prog Lipid Res 2020; 80:101065. [PMID: 32966869 DOI: 10.1016/j.plipres.2020.101065] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Revised: 08/14/2020] [Accepted: 09/17/2020] [Indexed: 12/20/2022]
Abstract
Phosphoinositide-specific phospholipase Cs (PLCs) are expressed in all mammalian cells and play critical roles in signal transduction. To obtain a comprehensive understanding of these enzymes in physiology and pathology, a detailed structural, biochemical, cell biological and genetic information is required. In this review, we cover all these aspects to summarize current knowledge of the entire superfamily. The families of PLCs have expanded from 13 enzymes to 16 with the identification of the atypical PLCs in the human genome. Recent structural insights highlight the common themes that cover not only the substrate catalysis but also the mechanisms of activation. This involves the release of autoinhibitory interactions that, in the absence of stimulation, maintain classical PLC enzymes in their inactive forms. Studies of individual PLCs provide a rich repertoire of PLC function in different physiologies. Furthermore, the genetic studies discovered numerous mutated and rare variants of PLC enzymes and their link to human disease development, greatly expanding our understanding of their roles in diverse pathologies. Notably, substantial evidence now supports involvement of different PLC isoforms in the development of specific cancer types, immune disorders and neurodegeneration. These advances will stimulate the generation of new drugs that target PLC enzymes, and will therefore open new possibilities for treatment of a number of diseases where current therapies remain ineffective.
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Affiliation(s)
- Matilda Katan
- Institute of Structural and Molecular Biology, Division of Biosciences, University College London, Gower Street, London WC1E 6BT, UK
| | - Shamshad Cockcroft
- Department of Neuroscience, Physiology and Pharmacology, Division of Biosciences, University College London, 21 University Street, London WC1E 6JJ, UK.
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5
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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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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: 33] [Impact Index Per Article: 8.3] [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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Intramolecular electrostatic interactions contribute to phospholipase Cβ3 autoinhibition. Cell Signal 2019; 62:109349. [PMID: 31254604 DOI: 10.1016/j.cellsig.2019.109349] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 06/22/2019] [Accepted: 06/23/2019] [Indexed: 01/21/2023]
Abstract
Phospholipase Cβ (PLCβ) enzymes regulate second messenger production following the activation of G protein-coupled receptors (GPCRs). Under basal conditions, these enzymes are maintained in an autoinhibited state by multiple elements, including an insertion within the catalytic domain known as the X-Y linker. Although the PLCβ X-Y linker is variable in sequence and length, its C-terminus is conserved and features an acidic stretch, followed by a short helix. This helix interacts with residues near the active site, acting as a lid to sterically prevent substrate binding. However, deletions that remove the acidic stretch of the X-Y linker increase basal activity to the same extent as deletion of the entire X-Y linker. Thus, the acidic stretch may be the linchpin in autoinhibition mediated by the X-Y linker. We used site-directed mutagenesis and biochemical assays to investigate the importance of this acidic charge in mediating PLCβ3 autoinhibition. Loss of the acidic charge in the X-Y linker increases basal activity and decreases stability, consistent with loss of autoinhibition. However, introduction of compensatory electrostatic mutations on the surface of the PLCβ3 catalytic domain restore activity to basal levels. Thus, intramolecular electrostatics modulate autoinhibition by the X-Y linker.
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8
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Matsuo M, Kan Y, Kurihara K, Jimbo T, Imai M, Toyota T, Hirata Y, Suzuki K, Sugawara T. DNA Length-dependent Division of a Giant Vesicle-based Model Protocell. Sci Rep 2019; 9:6916. [PMID: 31061467 PMCID: PMC6502804 DOI: 10.1038/s41598-019-43367-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/23/2019] [Indexed: 02/07/2023] Open
Abstract
DNA is an essential carrier of sequence-based genetic information for all life today. However, the chemical and physical properties of DNA may also affect the structure and dynamics of a vesicle-based model protocell in which it is encapsulated. To test these effects, we constructed a polyethylene glycol-grafted giant vesicle system capable of undergoing growth and division. The system incorporates a specific interaction between DNA and lipophilic catalysts as well as components of PCR. We found that vesicle division depends on the length of the encapsulated DNA, and the self-assembly of an internal supramolecular catalyst possibly leads to the direct causal relationship between DNA length and the capacity of the vesicle to self-reproduce. These results may help elucidate how nucleic acids could have functioned in the division of prebiotic protocells.
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Affiliation(s)
- Muneyuki Matsuo
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, Tokyo, 153-8902, Japan.,Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), Myodaiji, Okazaki, Aichi, 444-8787, Japan
| | - Yumi Kan
- Department of Physics, Graduate School of Science, Ochanomizu University, Otsuka, Bunkyo, Tokyo, 112-8610, Japan
| | - Kensuke Kurihara
- Department of Creative Research, Exploratory Research Center on Life and Living Systems (ExCELLS), Myodaiji, Okazaki, Aichi, 444-8787, Japan.,Determent of Life and Coordination-Complex Molecular Science, Biomolecular Functions, Institute for Molecular Science, Myodaiji, Okazaki, Aichi, 444-8585, Japan
| | - Takehiro Jimbo
- Department of Physics, Graduate School of Science, Tohoku University, Aoba, Sendai, Miyagi, 980-8578, Japan
| | - Masayuki Imai
- Department of Physics, Graduate School of Science, Ochanomizu University, Otsuka, Bunkyo, Tokyo, 112-8610, Japan.,Department of Physics, Graduate School of Science, Tohoku University, Aoba, Sendai, Miyagi, 980-8578, Japan
| | - Taro Toyota
- Department of Basic Science, Graduate School of Arts and Sciences, The University of Tokyo, Komaba, Meguro, Tokyo, 153-8902, Japan. .,Universal Biology Institute, The University of Tokyo, Hongo, Bunkyo, Tokyo, 113-0033, Japan.
| | - Yuiko Hirata
- Department of Chemistry, Faculty of Science, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa, 259-1293, Japan
| | - Kentaro Suzuki
- Department of Chemistry, Faculty of Science, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa, 259-1293, Japan
| | - Tadashi Sugawara
- Department of Chemistry, Faculty of Science, Kanagawa University, Tsuchiya, Hiratsuka, Kanagawa, 259-1293, Japan.
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9
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Cebecauer M, Amaro M, Jurkiewicz P, Sarmento MJ, Šachl R, Cwiklik L, Hof M. Membrane Lipid Nanodomains. Chem Rev 2018; 118:11259-11297. [PMID: 30362705 DOI: 10.1021/acs.chemrev.8b00322] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Lipid membranes can spontaneously organize their components into domains of different sizes and properties. The organization of membrane lipids into nanodomains might potentially play a role in vital functions of cells and organisms. Model membranes represent attractive systems to study lipid nanodomains, which cannot be directly addressed in living cells with the currently available methods. This review summarizes the knowledge on lipid nanodomains in model membranes and exposes how their specific character contrasts with large-scale phase separation. The overview on lipid nanodomains in membranes composed of diverse lipids (e.g., zwitterionic and anionic glycerophospholipids, ceramides, glycosphingolipids) and cholesterol aims to evidence the impact of chemical, electrostatic, and geometric properties of lipids on nanodomain formation. Furthermore, the effects of curvature, asymmetry, and ions on membrane nanodomains are shown to be highly relevant aspects that may also modulate lipid nanodomains in cellular membranes. Potential mechanisms responsible for the formation and dynamics of nanodomains are discussed with support from available theories and computational studies. A brief description of current fluorescence techniques and analytical tools that enabled progress in lipid nanodomain studies is also included. Further directions are proposed to successfully extend this research to cells.
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Affiliation(s)
- Marek Cebecauer
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Mariana Amaro
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Piotr Jurkiewicz
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Maria João Sarmento
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Radek Šachl
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Lukasz Cwiklik
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
| | - Martin Hof
- J. Heyrovský Institute of Physical Chemistry of the Czech Academy of Sciences , Dolejškova 3 , 18223 Prague 8 , Czech Republic
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Functional Optimization of Broadly Neutralizing HIV-1 Antibody 10E8 by Promotion of Membrane Interactions. J Virol 2018; 92:JVI.02249-17. [PMID: 29386285 DOI: 10.1128/jvi.02249-17] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 01/26/2018] [Indexed: 11/20/2022] Open
Abstract
The 10E8 antibody targets a helical epitope in the membrane-proximal external region (MPER) and transmembrane domain (TMD) of the envelope glycoprotein (Env) subunit gp41 and is among the broadest known neutralizing antibodies against HIV-1. Accordingly, this antibody and its mechanism of action valuably inform the design of effective vaccines and immunotherapies. 10E8 exhibits unusual adaptations to attain specific, high-affinity binding to the MPER at the viral membrane interface. Reversing the charge of the basic paratope surface (from net positive to net negative) reportedly lowered its neutralization potency. Here, we hypothesized that by increasing the net positive charge in similar polar surface patches, the neutralization potency of the antibody may be enhanced. We found that an increased positive charge at this paratope surface strengthened an electrostatic interaction between the antibody and lipid bilayers, enabling 10E8 to interact spontaneously with membranes. Notably, the modified 10E8 antibody did not gain any apparent polyreactivity and neutralized virus with a significantly greater potency. Binding analyses indicated that the optimized 10E8 antibody bound with a higher affinity to the epitope peptide anchored in lipid bilayers and to Env spikes on virions. Overall, our data provide a proof of principle for the rational optimization of 10E8 via manipulation of its interaction with the membrane element of its epitope. However, the observation that a similar mutation strategy did not affect the potency of the first-generation anti-MPER antibody 4E10 shows possible limitations of this principle. Altogether, our results emphasize the crucial role played by the viral membrane in the antigenicity of the MPER-TMD of HIV-1.IMPORTANCE The broadly neutralizing antibody 10E8 blocks infection by nearly all HIV-1 isolates, a capacity which vaccine design seeks to reproduce. Engineered versions of this antibody also represent a promising treatment for HIV infection by passive immunization. Understanding its mechanism of action is therefore important to help in developing effective vaccines and biologics to combat HIV/AIDS. 10E8 engages its helical MPER epitope where the base of the envelope spike submerges into the viral membrane. To enable this interaction, this antibody evolved an unusual property: the ability to interact with the membrane surface. Here, we provide evidence that 10E8 can be made more effective by enhancing its interactions with membranes. Our findings strengthen the idea that to elicit antibodies similar to 10E8, vaccines must reproduce the membrane environment where these antibodies perform their function.
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Kashir J, Nomikos M, Lai FA. Phospholipase C zeta and calcium oscillations at fertilisation: The evidence, applications, and further questions. Adv Biol Regul 2017; 67:148-162. [PMID: 29108881 DOI: 10.1016/j.jbior.2017.10.012] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 10/25/2017] [Accepted: 10/25/2017] [Indexed: 12/26/2022]
Abstract
Oocyte activation is a fundamental event at mammalian fertilisation, initiated by a series of characteristic calcium (Ca2+) oscillations in mammals. This characteristic pattern of Ca2+ release is induced in a species-specific manner by a sperm-specific enzyme termed phospholipase C zeta (PLCζ). Reduction or absence of functional PLCζ within sperm underlies male factor infertility in humans, due to mutational inactivation or abrogation of PLCζ protein expression. Underlying such clinical implications, a significant body of evidence has now been accumulated that has characterised the unique biochemical and biophysical properties of this enzyme, further aiding the unique clinical opportunities presented. Herein, we present and discuss evidence accrued over the past decade and a half that serves to support the identity of PLCζ as the mammalian sperm factor. Furthermore, we also discuss the potential novel avenues that have yet to be examined regarding PLCζ mechanism of action in both the oocyte, and the sperm. Finally, we discuss the advances that have been made regarding the clinical therapeutic and diagnostic applications of PLCζ in potentially treating male infertility as a result of oocyte activation deficiency (OAD), and also possibly more general cases of male subfertility.
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Affiliation(s)
- Junaid Kashir
- College of Biomedical & Life Sciences, School of Biosciences, Cardiff University, Cardiff, UK; Alfaisal University, College of Medicine, Riyadh, Saudi Arabia; King Faisal Specialist Hospital & Research Center, Department of Comparative Medicine, Riyadh, Saudi Arabia.
| | - Michail Nomikos
- College of Medicine, Member of QU Health, Qatar University, PO Box 2713, Doha, Qatar
| | - F Anthony Lai
- College of Biomedical & Life Sciences, School of Biosciences, Cardiff University, Cardiff, UK; College of Medicine, Member of QU Health, Qatar University, PO Box 2713, Doha, Qatar.
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12
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The role and mechanism of action of sperm PLC-zeta in mammalian fertilisation. Biochem J 2017; 474:3659-3673. [PMID: 29061915 DOI: 10.1042/bcj20160521] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 09/14/2017] [Accepted: 09/18/2017] [Indexed: 12/26/2022]
Abstract
At mammalian fertilisation, the fundamental stimulus that triggers oocyte (egg) activation and initiation of early embryonic development is an acute rise of the intracellular-free calcium (Ca2+) concentration inside the egg cytoplasm. This essential Ca2+ increase comprises a characteristic series of repetitive Ca2+ oscillations, starting soon after sperm-egg fusion. Over the last 15 years, accumulating scientific and clinical evidence supports the notion that the physiological stimulus that precedes the cytosolic Ca2+ oscillations is a novel, testis-specific phospholipase C (PLC) isoform, known as PLC-zeta (PLCζ). Sperm PLCζ catalyses the hydrolysis of phosphatidylinositol 4,5-bisphosphate triggering cytosolic Ca2+ oscillations through the inositol 1,4,5-trisphosphate signalling pathway. PLCζ is the smallest known mammalian PLC isoform with the most elementary domain organisation. However, relative to somatic PLCs, the PLCζ isoform possesses a unique potency in stimulating Ca2+ oscillations in eggs that is attributed to its novel biochemical characteristics. In this review, we discuss the latest developments that have begun to unravel the vital role of PLCζ at mammalian fertilisation and decipher its unique mechanism of action within the fertilising egg. We also postulate the significant potential diagnostic and therapeutic capacity of PLCζ in alleviating certain types of male infertility.
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13
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Atabay EP, Tadeo RD, Atabay EC, Venturina EV, Fissore RA, Mingala CN. Molecular Characterization and Comparison of Phospholipase C zeta (PLCZ1) Gene Between Swamp (Bubalus carabanensis) and Riverine (Bubalus bubalis) Buffaloes: Its Implications and Future Perspectives. Anim Biotechnol 2017; 29:190-198. [PMID: 28799828 DOI: 10.1080/10495398.2017.1350689] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Phospholipase C zeta, a novel sperm-specific protein which is widely known to induce oocyte activation following fertilization, had already been characterized in various mammalian species, but not in water buffaloes thus far. The present study was conducted to initially characterize and compare the sequences of PLCZ1 gene of swamp and riverine buffaloes. Semen samples were collected; total RNA was extracted and reverse-transcribed. PLCZ1 cDNA was then amplified, and submitted for sequencing. Buffalo PLCZ1 gene yielded a sequence of 1905 base pair nucleotides translated into 634 bp amino acids. In general, the buffalo PLCZ1 gene was found to have high sequence identity with cattle and other domestic species. Similarly, significant residues and motifs in PLCZ1 gene sequence are found conserved in water buffaloes. However, there are variations in sequences identified between types of water buffaloes that may play a role in species-specific differences in terms of gene and protein expression, physiological mechanisms, and biological functions. The molecular information on buffalo PLCZ1 gene is highly valuable in subsequent works such as correlation studies on the identified gene variations with semen quality and fertility, and the development of biomarkers for bull fertility.
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Affiliation(s)
- Eufrocina P Atabay
- a Philippine Carabao Center, National Headquarters, Science City of Munoz , Nueva Ecija , Philippines
| | - Roseline D Tadeo
- a Philippine Carabao Center, National Headquarters, Science City of Munoz , Nueva Ecija , Philippines
| | - Edwin C Atabay
- b Philipine Carabao Center, Central Luzon State University, Science City of Munoz , Nueva Ecija , Philippines
| | - Emma V Venturina
- b Philipine Carabao Center, Central Luzon State University, Science City of Munoz , Nueva Ecija , Philippines
| | - Rafael A Fissore
- c Department of Veterinary and Animal Sciences , University of Massachusetts , Amherst , Massachusetts , USA
| | - Claro N Mingala
- a Philippine Carabao Center, National Headquarters, Science City of Munoz , Nueva Ecija , Philippines
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14
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Rujas E, Caaveiro JMM, Insausti S, García-Porras M, Tsumoto K, Nieva JL. Peripheral Membrane Interactions Boost the Engagement by an Anti-HIV-1 Broadly Neutralizing Antibody. J Biol Chem 2017; 292:5571-5583. [PMID: 28213514 DOI: 10.1074/jbc.m117.775429] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 02/16/2017] [Indexed: 12/16/2022] Open
Abstract
The 4E10 antibody displays an extreme breadth of HIV-1 neutralization and therefore constitutes a suitable model system for structure-guided vaccine design and immunotherapeutics against AIDS. In this regard, the relevance of autoreactivity with membrane lipids for the biological function of this antibody is still a subject of controversy. To address this dispute, herein we have compared the membrane partitioning ability of the 4E10 antibody and several of its variants, which were mutated at the region of the paratope surface in contact with the membrane interface. We first employed a physical separation approach (vesicle flotation) and subsequently carried out quantitative fluorescence measurements in an intact system (spectroscopic titration), using 4E10 Fab labeled with a polarity-sensitive fluorescent probe. Moreover, recognition of epitope peptide in membrane was demonstrated by photo-cross-linking assays using a Fab that incorporated the genetically encoded unnatural amino acid p-benzoylphenylalanine. The experimental data ruled out that the proposed stereospecific recognition of viral lipids was necessary for the function of the antibody. In contrast, our data suggest that nonspecific electrostatic interactions between basic residues of 4E10 and acidic phospholipids in the membranes contribute to the observed biological function. Moreover, the energetics of membrane partitioning indicated that 4E10 behaves as a peripheral membrane protein, tightening the binding to the ligand epitope inserted in the viral membrane. The implications of these findings for the natural production and biological function of this antibody are discussed.
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Affiliation(s)
- Edurne Rujas
- From the Biofisika Institute (Consejo Superior de Investigaciones Científicas, UPV/EHU), and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain and.,the Department of Bioengineering, Graduate School of Engineering, University of Tokyo, Tokyo, 113-8656, Japan
| | - José M M Caaveiro
- the Department of Bioengineering, Graduate School of Engineering, University of Tokyo, Tokyo, 113-8656, Japan
| | - Sara Insausti
- From the Biofisika Institute (Consejo Superior de Investigaciones Científicas, UPV/EHU), and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain and
| | - Miguel García-Porras
- From the Biofisika Institute (Consejo Superior de Investigaciones Científicas, UPV/EHU), and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain and
| | - Kouhei Tsumoto
- the Department of Bioengineering, Graduate School of Engineering, University of Tokyo, Tokyo, 113-8656, Japan
| | - José L Nieva
- From the Biofisika Institute (Consejo Superior de Investigaciones Científicas, UPV/EHU), and Department of Biochemistry and Molecular Biology, University of the Basque Country (UPV/EHU), 48080 Bilbao, Spain and
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15
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16
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Abstract
A series of intracellular oscillations in the free cytosolic Ca(2+) concentration is responsible for activating mammalian eggs at fertilization, thus initiating embryo development. It has been proposed that the sperm causes these Ca(2+) oscillations after membrane fusion by delivering a soluble protein into the egg cytoplasm. We previously identified sperm-specific phospholipase C (PLC)-ζ as a protein that can trigger the same pattern of Ca(2+) oscillations in eggs seen at fertilization. PLCζ appears to be the elusive sperm factor mediating egg activation in mammals. It has potential therapeutic use in infertility treatments to improve the rate of egg activation and early embryo development after intra-cytoplasmic sperm injection. A stable form of recombinant human PLCζ could be a prototype for use in such in vitro fertilization (IVF) treatments. We do not yet understand exactly how PLCζ causes inositol 1,4,5-trisphosphate (InsP3) production in eggs. Sperm PLCζ is distinct among mammalian PI-specific PLCs in that it is far more potent in triggering Ca(2+) oscillations in eggs than other PLCs, but it lacks a PH domain that would otherwise be considered essential for binding to the phosphatidylinositol 4,5-bisphosphate (PIP2) substrate. PLCζ is also unusual in that it does not appear to interact with or hydrolyse plasma membrane PIP2. We consider how other regions of PLCζ may mediate its binding to PIP2 in eggs and how interaction of PLCζ with egg-specific factors could enable the hydrolysis of internal sources of PIP2.
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17
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Abd-El-Haliem AM, Vossen JH, van Zeijl A, Dezhsetan S, Testerink C, Seidl MF, Beck M, Strutt J, Robatzek S, Joosten MHAJ. Biochemical characterization of the tomato phosphatidylinositol-specific phospholipase C (PI-PLC) family and its role in plant immunity. Biochim Biophys Acta Mol Cell Biol Lipids 2016; 1861:1365-1378. [PMID: 26825689 DOI: 10.1016/j.bbalip.2016.01.017] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Revised: 01/18/2016] [Accepted: 01/23/2016] [Indexed: 10/22/2022]
Abstract
Plants possess effective mechanisms to quickly respond to biotic and abiotic stresses. The rapid activation of phosphatidylinositol-specific phospholipase C (PLC) enzymes occurs early after the stimulation of plant immune-receptors. Genomes of different plant species encode multiple PLC homologs belonging to one class, PLCζ. Here we determined whether all tomato homologs encode active enzymes and whether they can generate signals that are distinct from one another. We searched the recently completed tomato (Solanum lycopersicum) genome sequence and identified a total of seven PLCs. Recombinant proteins were produced for all tomato PLCs, except for SlPLC7. The purified proteins showed typical PLC activity, as different PLC substrates were hydrolysed to produce diacylglycerol. We studied SlPLC2, SlPLC4 and SlPLC5 enzymes in more detail and observed distinct requirements for Ca(2+) ions and pH, for both their optimum activity and substrate preference. This indicates that each enzyme could be differentially and specifically regulated in vivo, leading to the generation of PLC homolog-specific signals in response to different stimuli. PLC overexpression and specific inhibition of PLC activity revealed that PLC is required for both specific effector- and more general "pattern"-triggered immunity. For the latter, we found that both the flagellin-triggered response and the internalization of the corresponding receptor, Flagellin Sensing 2 (FLS2) of Arabidopsis thaliana, are suppressed by inhibition of PLC activity. Altogether, our data support an important role for PLC enzymes in plant defence signalling downstream of immune receptors. This article is part of a Special Issue entitled: Plant Lipid Biology edited by Kent D. Chapman and Ivo Feussner.
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Affiliation(s)
- Ahmed M Abd-El-Haliem
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Jack H Vossen
- Laboratory of Plant Breeding, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Arjan van Zeijl
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Sara Dezhsetan
- Laboratory of Plant Breeding, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Christa Testerink
- Plant Physiology, Swammerdam Institute for Life Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - Michael F Seidl
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Martina Beck
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - James Strutt
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Silke Robatzek
- The Sainsbury Laboratory, Norwich Research Park, Norwich NR4 7UH, UK
| | - Matthieu H A J Joosten
- Laboratory of Phytopathology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands.
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18
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Machaty Z. Signal transduction in mammalian oocytes during fertilization. Cell Tissue Res 2016; 363:169-183. [PMID: 26453398 PMCID: PMC4700098 DOI: 10.1007/s00441-015-2291-8] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Accepted: 08/28/2015] [Indexed: 01/22/2023]
Abstract
Mammalian embryo development begins when the fertilizing sperm triggers a series of elevations in the oocyte's intracellular free Ca(2+) concentration. The elevations are the result of repeated release and re-uptake of Ca(2+) stored in the smooth endoplasmic reticulum. Ca(2+) release is primarily mediated by the phosphoinositide signaling system of the oocyte. The system is stimulated when the sperm causes the hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG); IP3 then binds its receptor on the surface of the endoplasmic reticulum that induces Ca(2+) release. The manner in which the sperm generates IP3, the Ca(2+) mobilizing second messenger, has been the subject of extensive research for a long time. The sperm factor hypothesis has eventually gained general acceptance, according to which it is a molecule from the sperm that diffuses into the ooplasm and stimulates the phosphoinositide cascade. Much evidence now indicates that the sperm-derived factor is phospholipase C-zeta (PLCζ) that cleaves PIP2 and generates IP3, eventually leading to oocyte activation. A recent addition to the candidate sperm factor list is the post-acrosomal sheath WW domain-binding protein (PAWP), whose role at fertilization is currently under debate. Ca(2+) influx across the plasma membrane is also important as, in the absence of extracellular Ca(2+), the oscillations run down prematurely. In pig oocytes, the influx that sustains the oscillations seems to be regulated by the filling status of the stores, whereas in the mouse other mechanisms might be involved. This work summarizes the current understanding of Ca(2+) signaling in mammalian oocytes.
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Affiliation(s)
- Zoltan Machaty
- Department of Animal Sciences, Purdue University, 915 W. State Street, West Lafayette, IN, 47907, USA.
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19
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Abstract
The most fundamental unresolved issue of fertilization is to define how the sperm activates the egg to begin embryo development. Egg activation at fertilization in all species thus far examined is caused by some form of transient increase in the cytoplasmic free Ca2+ concentration. What has not been clear, however, is precisely how the sperm triggers the large changes in Ca2+ observed within the egg cytoplasm. Here, we review the studies indicating that the fertilizing sperm stimulates a cytosolic Ca2+ increase in the egg specifically by delivering a soluble factor that diffuses into the cytosolic space of the egg upon gamete membrane fusion. Evidence is primarily considered in species of eggs where the sperm has been shown to elicit a cytosolic Ca2+ increase by initiating Ca2+ release from intracellular Ca2+ stores. We suggest that our best understanding of these signaling events is in mammals, where the sperm triggers a prolonged series of intracellular Ca2+ oscillations. The strongest empirical studies to date suggest that mammalian sperm-triggered Ca2+ oscillations are caused by the introduction of a sperm-specific protein, called phospholipase C-zeta (PLCζ) that generates inositol trisphosphate within the egg. We will discuss the role and mechanism of action of PLCζ in detail at a molecular and cellular level. We will also consider some of the evidence that a soluble sperm protein might be involved in egg activation in nonmammalian species.
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Affiliation(s)
- Karl Swann
- College of Biomedical and Life Sciences, School of Medicine, Cardiff University, Cardiff, United Kingdom
| | - F. Anthony Lai
- College of Biomedical and Life Sciences, School of Medicine, Cardiff University, Cardiff, United Kingdom
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20
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Nomikos M, Sanders JR, Parthimos D, Buntwal L, Calver BL, Stamatiadis P, Smith A, Clue M, Sideratou Z, Swann K, Lai FA. Essential Role of the EF-hand Domain in Targeting Sperm Phospholipase Cζ to Membrane Phosphatidylinositol 4,5-Bisphosphate (PIP2). J Biol Chem 2015; 290:29519-30. [PMID: 26429913 PMCID: PMC4705952 DOI: 10.1074/jbc.m115.658443] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Indexed: 11/25/2022] Open
Abstract
Sperm-specific phospholipase C-ζ (PLCζ) is widely considered to be the physiological stimulus that triggers intracellular Ca2+ oscillations and egg activation during mammalian fertilization. Although PLCζ is structurally similar to PLCδ1, it lacks a pleckstrin homology domain, and it remains unclear how PLCζ targets its phosphatidylinositol 4,5-bisphosphate (PIP2) membrane substrate. Recently, the PLCδ1 EF-hand domain was shown to bind to anionic phospholipids through a number of cationic residues, suggesting a potential mechanism for how PLCs might interact with their target membranes. Those critical cationic EF-hand residues in PLCδ1 are notably conserved in PLCζ. We investigated the potential role of these conserved cationic residues in PLCζ by generating a series of mutants that sequentially neutralized three positively charged residues (Lys-49, Lys-53, and Arg-57) within the mouse PLCζ EF-hand domain. Microinjection of the PLCζ EF-hand mutants into mouse eggs enabled their Ca2+ oscillation inducing activities to be compared with wild-type PLCζ. Furthermore, the mutant proteins were purified, and the in vitro PIP2 hydrolysis and binding properties were monitored. Our analysis suggests that PLCζ binds significantly to PIP2, but not to phosphatidic acid or phosphatidylserine, and that sequential reduction of the net positive charge within the first EF-hand domain of PLCζ significantly alters in vivo Ca2+ oscillation inducing activity and in vitro interaction with PIP2 without affecting its Ca2+ sensitivity. Our findings are consistent with theoretical predictions provided by a mathematical model that links oocyte Ca2+ frequency and the binding ability of different PLCζ mutants to PIP2. Moreover, a PLCζ mutant with mutations in the cationic residues within the first EF-hand domain and the XY linker region dramatically reduces the binding of PLCζ to PIP2, leading to complete abolishment of its Ca2+ oscillation inducing activity.
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Affiliation(s)
- Michail Nomikos
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
| | - Jessica R Sanders
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
| | - Dimitris Parthimos
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
| | - Luke Buntwal
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
| | - Brian L Calver
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
| | - Panagiotis Stamatiadis
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
| | - Adrian Smith
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
| | - Matthew Clue
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
| | - Zili Sideratou
- the National Center for Scientific Research "Demokritos," 15310 Aghia Paraskevi, Greece
| | - Karl Swann
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
| | - F Anthony Lai
- From the Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom and
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21
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Yeste M, Jones C, Amdani SN, Patel S, Coward K. Oocyte activation deficiency: a role for an oocyte contribution? Hum Reprod Update 2015; 22:23-47. [DOI: 10.1093/humupd/dmv040] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 08/13/2015] [Indexed: 12/11/2022] Open
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22
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Arduin A, Gaffney PRJ, Ces O. Regulation of PLCβ2 by the electrostatic and mechanical properties of lipid bilayers. Sci Rep 2015; 5:12628. [PMID: 26243281 PMCID: PMC4525138 DOI: 10.1038/srep12628] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Accepted: 06/19/2015] [Indexed: 11/09/2022] Open
Abstract
Phosphoinositide-specific phospholipase C (PLC) is an important family of enzymes constituting a junction between phosphoinositide lipid signaling and the trans-membrane signal transduction processes that are crucial to many living cells. However, the regulatory mechanism of PLC is not yet understood in detail. To address this issue, activity studies were carried out using lipid vesicles in a model system that was specifically designed to study protein-protein and lipid-protein interactions in concert. Evidence was found for a direct interaction between PLC and the GTPases that mediate phospholipase activation. Furthermore, for the first time, the relationships between PLC activity and substrate presentation in lipid vesicles of various sizes, as well as lipid composition and membrane mechanical properties, were analyzed. PLC activity was found to depend upon the electrostatic potential and the stored curvature elastic stress of the lipid membranes.
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Affiliation(s)
- Alessia Arduin
- Institute of Chemical Biology, Department of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Piers R. J. Gaffney
- Institute of Chemical Biology, Department of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
| | - Oscar Ces
- Institute of Chemical Biology, Department of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, United Kingdom
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23
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Nomikos M, Sanders JR, Kashir J, Sanusi R, Buntwal L, Love D, Ashley P, Sanders D, Knaggs P, Bunkheila A, Swann K, Lai FA. Functional disparity between human PAWP and PLCζ in the generation of Ca2+ oscillations for oocyte activation. Mol Hum Reprod 2015; 21:702-10. [PMID: 26116451 DOI: 10.1093/molehr/gav034] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/19/2015] [Indexed: 11/14/2022] Open
Abstract
Mammalian oocyte activation is mediated by cytosolic calcium (Ca(2+)) oscillations initiated upon delivery of a putative 'sperm factor' by the fertilizing sperm. Previous studies suggest the identity of this sperm factor as the testis-specific phospholipase C-zeta (PLCζ). Recently, a post-acrosomal sheath WW domain-binding protein (PAWP) has been proposed as an alternative sperm factor candidate, following a report that human PAWP protein and cRNA elicited Ca(2+) oscillations in mouse and human oocytes. Those Ca(2+) oscillations were inhibited by a PAWP-derived peptide corresponding to a functional PPGY binding motif. Herein, using a series of human PAWP expression constructs, we demonstrate that both human PAWP protein and cRNA are, in our experiments, unable to elicit Ca(2+) release following microinjection into mouse oocytes. Parallel experiments performed with human PLCζ elicited the characteristic Ca(2+) oscillations present at mammalian fertilization, which produced oocyte activation and embryo development. Furthermore, sperm-induced Ca(2+) oscillations were not inhibited by the PAWP-derived PPGY peptide following in vitro fertilization or intracytoplasmic sperm injection. Thus, the functional disparity with PLCζ leads us to conclude that human PAWP is neither sufficient nor necessary for the Ca(2+) oscillations that initiate mammalian oocyte activation at fertilization.
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Affiliation(s)
- Michail Nomikos
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - Jessica R Sanders
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - Junaid Kashir
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK College of Medicine, Alfaisal University, Riyadh, Kingdom of Saudi Arabia Department of Comparative Medicine, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia
| | - Randa Sanusi
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - Luke Buntwal
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - Daniel Love
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - Peter Ashley
- Wales Fertility Institute, University Hospital of Wales, Cardiff CF14 4XW, UK
| | - David Sanders
- Wales Fertility Institute, University Hospital of Wales, Cardiff CF14 4XW, UK
| | - Paul Knaggs
- Wales Fertility Institute, University Hospital of Wales, Cardiff CF14 4XW, UK
| | - Adnan Bunkheila
- Wales Fertility Institute, University Hospital of Wales, Cardiff CF14 4XW, UK
| | - Karl Swann
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - F Anthony Lai
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
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24
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Abstract
Egg activation is the first step of embryonic development and in mammals is triggered by a series of cytoplasmic calcium (Ca2+) oscillations. Sperm–egg fusion initiates these Ca2+ oscillations by introducing a sperm-specific protein factor into the egg cytoplasm. Substantial evidence indicates that this protein is a sperm-specific phospholipase C (PLC), termed PLC-zeta (PLCζ). PLCζ stimulates cytoplasmic Ca2+ oscillations matching those at fertilization triggering early embryonic development in several mammalian species. Structurally, PLCζ is comprised of four EF-hands, a C2 domain, and X and Y catalytic domains. PLCζ is an unusual PLC since it lacks a pleckstrin homology (PH) domain. It is also distinctive in that its X–Y linker is not involved in auto-inhibition of catalytic activity, but instead binds to phosphatidylinositol 4,5-bisphosphate (PIP2). Moreover, relative to other PLC isoforms, PLCζ possesses unique potency in stimulating Ca2+ oscillations in eggs, although it does not appear to bind to plasma membrane PIP2. In contrast, PLCζ appears to interact with intracellular vesicles in eggs that contain PIP2. I discuss the recent advances in our knowledge of the intriguing biochemical and physiological properties of sperm PLCζ and postulate potential roles for PLCζ in terms of clinical diagnosis and therapy for certain forms of male infertility.
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25
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Functional diversification and specialization of cytosolic 70-kDa heat shock proteins. Sci Rep 2015; 5:9363. [PMID: 25791537 PMCID: PMC4366816 DOI: 10.1038/srep09363] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 03/02/2015] [Indexed: 02/04/2023] Open
Abstract
A fundamental question in molecular evolution is how protein functional differentiation alters the ability of cells and organisms to cope with stress and survive. To answer this question we used two paralogous Hsp70s from mouse and explored whether these highly similar cytosolic molecular chaperones, which apart their temporal expression have been considered functionally interchangeable, are differentiated with respect to their lipid-binding function. We demonstrate that the two proteins bind to diverse lipids with different affinities and therefore are functionally specialized. The observed lipid-binding patterns may be related with the ability of both Hsp70s to induce cell death by binding to a particular plasma-membrane lipid, and the potential of only one of them to promote cell survival by binding to a specific lysosomal-membrane lipid. These observations reveal that two seemingly identical proteins differentially modulate cellular adaptation and survival by having acquired specialized functions via sequence divergence. Therefore, this study provides an evolutionary paradigm, where promiscuity, specificity, sub- and neo-functionalization orchestrate one of the most conserved systems in nature, the cellular stress-response.
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26
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Ca2+ Regulation of Trypanosoma brucei Phosphoinositide Phospholipase C. EUKARYOTIC CELL 2015; 14:486-94. [PMID: 25769297 DOI: 10.1128/ec.00019-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2015] [Accepted: 03/09/2015] [Indexed: 11/20/2022]
Abstract
We characterized a phosphoinositide phospholipase C (PI-PLC) from the procyclic form (PCF) of Trypanosoma brucei. The protein contains a domain organization characteristic of typical PI-PLCs, such as X and Y catalytic domains, an EF-hand calcium-binding motif, and a C2 domain, but it lacks a pleckstrin homology (PH) domain. In addition, the T. brucei PI-PLC (TbPI-PLC) contains an N-terminal myristoylation consensus sequence found only in trypanosomatid PI-PLCs. A peptide containing this N-terminal domain fused to green fluorescent protein (GFP) was targeted to the plasma membrane. TbPI-PLC enzymatic activity was stimulated by Ca(2+) concentrations below the cytosolic levels in the parasite, suggesting that the enzyme is constitutively active. TbPI-PLC hydrolyzes both phosphatidylinositol (PI) and phosphatidylinositol 4,5-bisphosphate (PIP2), with a higher affinity for PIP2. We found that modification of a single amino acid in the EF-hand motif greatly affected the protein's Ca(2+) sensitivity and substrate preference, demonstrating the role of this motif in Ca(2+) regulation of TbPI-PLC. Endogenous TbPI-PLC localizes to intracellular vesicles and might be using an intracellular source of PIP2. Knockdown of TbPI-PLC expression by RNA interference (RNAi) did not result in growth inhibition, although enzymatic activity was still present in parasites, resulting in hydrolysis of PIP2 and a contribution to the inositol 1,4,5-trisphosphate (IP3)/diacylglycerol (DAG) pathway.
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27
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Stith BJ. Phospholipase C and D regulation of Src, calcium release and membrane fusion during Xenopus laevis development. Dev Biol 2015; 401:188-205. [PMID: 25748412 DOI: 10.1016/j.ydbio.2015.02.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 02/15/2015] [Accepted: 02/24/2015] [Indexed: 11/28/2022]
Abstract
This review emphasizes how lipids regulate membrane fusion and the proteins involved in three developmental stages: oocyte maturation to the fertilizable egg, fertilization and during first cleavage. Decades of work show that phosphatidic acid (PA) releases intracellular calcium, and recent work shows that the lipid can activate Src tyrosine kinase or phospholipase C during Xenopus fertilization. Numerous reports are summarized to show three levels of increase in lipid second messengers inositol 1,4,5-trisphosphate and sn 1,2-diacylglycerol (DAG) during the three different developmental stages. In addition, possible roles for PA, ceramide, lysophosphatidylcholine, plasmalogens, phosphatidylinositol 4-phosphate, phosphatidylinositol 5-phosphate, phosphatidylinositol 4,5-bisphosphate, membrane microdomains (rafts) and phosphatidylinositol 3,4,5-trisphosphate in regulation of membrane fusion (acrosome reaction, sperm-egg fusion, cortical granule exocytosis), inositol 1,4,5-trisphosphate receptors, and calcium release are discussed. The role of six lipases involved in generating putative lipid second messengers during fertilization is also discussed: phospholipase D, autotaxin, lipin1, sphingomyelinase, phospholipase C, and phospholipase A2. More specifically, proteins involved in developmental events and their regulation through lipid binding to SH3, SH4, PH, PX, or C2 protein domains is emphasized. New models are presented for PA activation of Src (through SH3, SH4 and a unique domain), that this may be why the SH2 domain of PLCγ is not required for Xenopus fertilization, PA activation of phospholipase C, a role for PA during the calcium wave after fertilization, and that calcium/calmodulin may be responsible for the loss of Src from rafts after fertilization. Also discussed is that the large DAG increase during fertilization derives from phospholipase D production of PA and lipin dephosphorylation to DAG.
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Affiliation(s)
- Bradley J Stith
- University of Colorado Denver, Department of Integrative Biology, Campus Box 171, PO Box 173364, Denver, CO 80217-3364, United States.
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28
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Kashir J, Nomikos M, Swann K, Lai FA. PLCζ or PAWP: revisiting the putative mammalian sperm factor that triggers egg activation and embryogenesis. ACTA ACUST UNITED AC 2015; 21:383-8. [DOI: 10.1093/molehr/gav009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 02/23/2015] [Indexed: 01/03/2023]
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29
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Kashir J, Nomikos M, Lai FA, Swann K. Sperm-induced Ca2+ release during egg activation in mammals. Biochem Biophys Res Commun 2014; 450:1204-11. [PMID: 24769204 DOI: 10.1016/j.bbrc.2014.04.078] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 04/15/2014] [Indexed: 12/12/2022]
Abstract
This review discusses the role that the sperm-specific phospholipase C zeta (PLCζ) is proposed to play during the fertilization of mammalian eggs. At fertilization, the sperm initiates development by causing a series of oscillations in cytosolic concentrations of calcium [Ca(2)] within the egg. PLCζ mimics the sperm at fertilization, causing the same pattern of Ca(2+) release as seen at fertilization. Introducing PLCζ into mouse eggs also mimics a number of other features of the way in which the fertilizing sperm triggers Ca(2+) oscillations. We discuss the localization of PLCζ within the egg and present a hypothesis about the localization of PLCζ within the sperm before the initiation of fertilization.
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Affiliation(s)
- Junaid Kashir
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, UK
| | - Michail Nomikos
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, UK
| | - F Anthony Lai
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, UK
| | - Karl Swann
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, UK.
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Galassi VV, Villarreal MA, Posada V, Montich GG. Interactions of the fatty acid-binding protein ReP1-NCXSQ with lipid membranes. Influence of the membrane electric field on binding and orientation. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:910-20. [DOI: 10.1016/j.bbamem.2013.11.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 11/12/2013] [Accepted: 11/13/2013] [Indexed: 11/17/2022]
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Nomikos M, Theodoridou M, Elgmati K, Parthimos D, Calver BL, Buntwal L, Nounesis G, Swann K, Lai FA. Human PLCζ exhibits superior fertilization potency over mouse PLCζ in triggering the Ca(2+) oscillations required for mammalian oocyte activation. Mol Hum Reprod 2014; 20:489-98. [PMID: 24478462 DOI: 10.1093/molehr/gau011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A sperm-specific phospholipase C-zeta (PLCζ) is believed to play an essential role in oocyte activation during mammalian fertilization. Sperm PLCζ has been shown to trigger a prolonged series of repetitive Ca(2+) transients or oscillations in oocytes that precede activation. This remarkable intracellular Ca(2+) signalling phenomenon is a distinctive characteristic observed during in vitro fertilization by sperm. Previous studies have notably observed an apparent differential ability of PLCζ from disparate mammalian species to trigger Ca(2+) oscillations in mouse oocytes. However, the molecular basis and confirmation of the apparent PLCζ species difference in activity remains to be provided. In the present study, we provide direct evidence for the superior effectiveness of human PLCζ relative to mouse PLCζ in generating Ca(2+) oscillations in mouse oocytes. In addition, we have designed and constructed a series of human/mouse PLCζ chimeras to enable study of the potential role of discrete PLCζ domains in conferring the enhanced Ca(2+) signalling potency of human PLCζ. Functional analysis of these human/mouse PLCζ domain chimeras suggests a novel role of the EF-hand domain in the species-specific differences in PLCζ activity. Our empirical observations are compatible with a basic mathematical model for the Ca(2+) dependence of generating cytoplasmic Ca(2+) oscillations in mammalian oocytes by sperm PLCζ.
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Affiliation(s)
- Michail Nomikos
- Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - Maria Theodoridou
- Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK National Center for Scientific Research 'Demokritos', Aghia Paraskevi 15310, Greece
| | - Khalil Elgmati
- Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | | | - Brian L Calver
- Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - Luke Buntwal
- Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - George Nounesis
- National Center for Scientific Research 'Demokritos', Aghia Paraskevi 15310, Greece
| | - Karl Swann
- Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
| | - F Anthony Lai
- Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK
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PI-PLC: Phosphoinositide-Phospholipase C in Plant Signaling. SIGNALING AND COMMUNICATION IN PLANTS 2014. [DOI: 10.1007/978-3-642-42011-5_2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Theodoridou M, Nomikos M, Parthimos D, Gonzalez-Garcia JR, Elgmati K, Calver BL, Sideratou Z, Nounesis G, Swann K, Lai FA. Chimeras of sperm PLCζ reveal disparate protein domain functions in the generation of intracellular Ca2+ oscillations in mammalian eggs at fertilization. Mol Hum Reprod 2013; 19:852-64. [PMID: 24152875 DOI: 10.1093/molehr/gat070] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Phospholipase C-zeta (PLCζ) is a sperm-specific protein believed to cause Ca(2+) oscillations and egg activation during mammalian fertilization. PLCζ is very similar to the somatic PLCδ1 isoform but is far more potent in mobilizing Ca(2+) in eggs. To investigate how discrete protein domains contribute to Ca(2+) release, we assessed the function of a series of PLCζ/PLCδ1 chimeras. We examined their ability to cause Ca(2+) oscillations in mouse eggs, enzymatic properties using in vitro phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis and their binding to PIP2 and PI(3)P with a liposome interaction assay. Most chimeras hydrolyzed PIP2 with no major differences in Ca(2+) sensitivity and enzyme kinetics. Insertion of a PH domain or replacement of the PLCζ EF hands domain had no deleterious effect on Ca(2+) oscillations. In contrast, replacement of either XY-linker or C2 domain of PLCζ completely abolished Ca(2+) releasing activity. Notably, chimeras containing the PLCζ XY-linker bound to PIP2-containing liposomes, while chimeras containing the PLCζ C2 domain exhibited PI(3)P binding. Our data suggest that the EF hands are not solely responsible for the nanomolar Ca(2+) sensitivity of PLCζ and that membrane PIP2 binding involves the C2 domain and XY-linker of PLCζ. To investigate the relationship between PLC enzymatic properties and Ca(2+) oscillations in eggs, we have developed a mathematical model that incorporates Ca(2+)-dependent InsP3 generation by the PLC chimeras and their levels of intracellular expression. These numerical simulations can for the first time predict the empirical variability in onset and frequency of Ca(2+) oscillatory activity associated with specific PLC variants.
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Affiliation(s)
- Maria Theodoridou
- Institute of Molecular and Experimental Medicine, WHRI, Cardiff University School of Medicine, Cardiff CF14 4XN, UK
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Nomikos M, Kashir J, Swann K, Lai FA. Sperm PLCζ: from structure to Ca2+ oscillations, egg activation and therapeutic potential. FEBS Lett 2013; 587:3609-16. [PMID: 24157362 DOI: 10.1016/j.febslet.2013.10.008] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 10/12/2013] [Accepted: 10/14/2013] [Indexed: 10/26/2022]
Abstract
Significant evidence now supports the assertion that cytosolic calcium oscillations during fertilization in mammalian eggs are mediated by a testis-specific phospholipase C (PLC), termed PLC-zeta (PLCζ) that is released into the egg following gamete fusion. Herein, we describe the current paradigm of PLCζ in this fundamental biological process, summarizing recent important advances in our knowledge of the biochemical and physiological properties of this enzyme. We describe the data suggesting that PLCζ has distinct features amongst PLCs enabling the hydrolysis of its substrate, phosphatidylinositol 4,5-bisphosphate (PIP2) at low Ca(2+) levels. PLCζ appears to be unique in its ability to target PIP2 that is present on intracellular vesicles. We also discuss evidence that PLCζ may be a significant factor in human fertility with potential therapeutic capacity.
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Affiliation(s)
- Michail Nomikos
- Institute of Molecular and Experimental Medicine, WHRI, Cardiff University School of Medicine, Heath Park, CF144XN Cardiff, UK.
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Kashir J, Deguchi R, Jones C, Coward K, Stricker SA. Comparative biology of sperm factors and fertilization-induced calcium signals across the animal kingdom. Mol Reprod Dev 2013; 80:787-815. [PMID: 23900730 DOI: 10.1002/mrd.22222] [Citation(s) in RCA: 77] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2013] [Accepted: 07/23/2013] [Indexed: 11/08/2022]
Abstract
Fertilization causes mature oocytes or eggs to increase their concentrations of intracellular calcium ions (Ca²⁺) in all animals that have been examined, and such Ca²⁺ elevations, in turn, provide key activating signals that are required for non-parthenogenetic development. Several lines of evidence indicate that the Ca²⁺ transients produced during fertilization in mammals and other taxa are triggered by soluble factors that sperm deliver into oocytes after gamete fusion. Thus, for a broad-based analysis of Ca²⁺ dynamics during fertilization in animals, this article begins by summarizing data on soluble sperm factors in non-mammalian species, and subsequently reviews various topics related to a sperm-specific phospholipase C, called PLCζ, which is believed to be the predominant activator of mammalian oocytes. After characterizing initiation processes that involve sperm factors or alternative triggering mechanisms, the spatiotemporal patterns of Ca²⁺ signals in fertilized oocytes or eggs are compared in a taxon-by-taxon manner, and broadly classified as either a single major transient or a series of repetitive oscillations. Both solitary and oscillatory types of fertilization-induced Ca²⁺ signals are typically propagated as global waves that depend on Ca²⁺ release from the endoplasmic reticulum in response to increased concentrations of inositol 1,4,5-trisphosphate (IP₃). Thus, for taxa where relevant data are available, upstream pathways that elevate intraoocytic IP3 levels during fertilization are described, while other less-common modes of producing Ca²⁺ transients are also examined. In addition, the importance of fertilization-induced Ca²⁺ signals for activating development is underscored by noting some major downstream effects of these signals in various animals.
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Affiliation(s)
- Junaid Kashir
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Headington, Oxford, UK
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Popovic M, Zlatev V, Hodnik V, Anderluh G, Felli IC, Pongor S, Pintar A. Flexibility of the PDZ-binding motif in the micelle-bound form of Jagged-1 cytoplasmic tail. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1818:1706-16. [PMID: 22465068 DOI: 10.1016/j.bbamem.2012.03.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Revised: 03/13/2012] [Accepted: 03/14/2012] [Indexed: 01/07/2023]
Abstract
Human Jagged-1, one of the ligands of Notch receptors, is a transmembrane protein composed of a large extracellular region and a 125-residue cytoplasmic tail which bears a C-terminal PDZ recognition motif. To investigate the interaction between Jagged-1 cytoplasmic tail and the inner leaflet of the plasma membrane we determined, by solution NMR, the secondary structure and dynamics of the recombinant protein corresponding to the intracellular region of Jagged-1, J1_tmic, bound to negatively charged lysophospholipid micelles. NMR showed that the PDZ binding motif is preceded by four alpha-helical segments and that, despite the extensive interaction between J1_tmic and the micelle, the PDZ binding motif remains highly flexible. Binding of J1_tmic to negatively charged, but not to zwitterionic vesicles, was confirmed by surface plasmon resonance. To study the PDZ binding region in more detail, we prepared a peptide corresponding to the last 24 residues of Jagged-1, J1C24, and different phosphorylated variants of it. J1C24 displays a marked helical propensity and undergoes a coil-helix transition in the presence of negatively charged, but not zwitterionic, lysophospholipid micelles. Phosphorylation at different positions drastically decreases the helical propensity of the peptides and abolishes the coil-helix transition triggered by lysophospholipid micelles. We propose that phosphorylation of residues upstream of the PDZ binding motif may shift the equilibrium from an ordered, membrane-bound, interfacial form of Jagged-1 C-terminal region to a more disordered form with an increased accessibility of the PDZ recognition motif, thus playing an indirect role in the interaction between Jagged-1 and the PDZ-containing target protein.
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Affiliation(s)
- Matija Popovic
- International Centre for Genetic Engineering and Biotechnology, AREA Science Park Padriciano 99, 1-34149 Trieste, Italy
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Cho H, Wu M, Bilgin B, Walton SP, Chan C. Latest developments in experimental and computational approaches to characterize protein-lipid interactions. Proteomics 2013; 12:3273-85. [PMID: 22997137 DOI: 10.1002/pmic.201200255] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2012] [Revised: 08/30/2012] [Accepted: 09/05/2012] [Indexed: 12/16/2022]
Abstract
Understanding the functional roles of all the molecules in cells is an ultimate goal of modern biology. An important facet is to understand the functional contributions from intermolecular interactions, both within a class of molecules (e.g. protein-protein) or between classes (e.g. protein-DNA). While the technologies for analyzing protein-protein and protein-DNA interactions are well established, the field of protein-lipid interactions is still relatively nascent. Here, we review the current status of the experimental and computational approaches for detecting and analyzing protein-lipid interactions. Experimental technologies fall into two principal categories, namely solution-based and array-based methods. Computational methods include large-scale data-driven analyses and predictions/dynamic simulations based on prior knowledge of experimentally identified interactions. Advances in the experimental technologies have led to improved computational analyses and vice versa, thereby furthering our understanding of protein-lipid interactions and their importance in biological systems.
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Affiliation(s)
- Hyunju Cho
- Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI, USA
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Nomikos M, Yu Y, Elgmati K, Theodoridou M, Campbell K, Vassilakopoulou V, Zikos C, Livaniou E, Amso N, Nounesis G, Swann K, Lai FA. Phospholipase Cζ rescues failed oocyte activation in a prototype of male factor infertility. Fertil Steril 2013; 99:76-85. [PMID: 22999959 PMCID: PMC3540263 DOI: 10.1016/j.fertnstert.2012.08.035] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2012] [Revised: 08/15/2012] [Accepted: 08/20/2012] [Indexed: 11/16/2022]
Abstract
OBJECTIVE To determine the effect of infertility-linked sperm phospholipase Cζ (PLCζ) mutations on their ability to trigger oocyte Ca(2+) oscillations and development, and also to evaluate the potential therapeutic utility of wild-type, recombinant PLCζ protein for rescuing failed oocyte activation and embryo development. DESIGN Test of a novel therapeutic approach to male factor infertility. SETTING University medical school research laboratory. PATIENT(S) Donated unfertilized human oocytes from follicle reduction. INTERVENTION(S) Microinjection of oocytes with recombinant human PLCζ protein or PLCζ cRNA and a Ca(2+)-sensitive fluorescent dye. MAIN OUTCOME MEASURE(S) Measurement of the efficacy of mutant and wild-type PLCζ-mediated enzyme activity, oocyte Ca(2+) oscillations, activation, and early embryo development. RESULT(S) In contrast to the wild-type protein, mutant forms of human sperm PLCζ display aberrant enzyme activity and a total failure to activate unfertilized oocytes. Subsequent microinjection of recombinant human PLCζ protein reliably triggers the characteristic pattern of cytoplasmic Ca(2+) oscillations at fertilization, which are required for normal oocyte activation and successful embryo development to the blastocyst stage. CONCLUSION(S) Dysfunctional sperm PLCζ cannot trigger oocyte activation and results in male factor infertility, so a potential therapeutic approach is oocyte microinjection of active, wild-type PLCζ protein. We have demonstrated that recombinant human PLCζ can phenotypically rescue failed activation in oocytes that express dysfunctional PLCζ, and that this intervention culminates in efficient blastocyst formation.
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Affiliation(s)
- Michail Nomikos
- Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom; National Center for Scientific Research "Demokritos," Aghia Paraskevi, Greece.
| | - Yuansong Yu
- Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Khalil Elgmati
- Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - Maria Theodoridou
- Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom; National Center for Scientific Research "Demokritos," Aghia Paraskevi, Greece
| | - Karen Campbell
- IVF Wales, University Hospital of Wales, Heath Park, Cardiff, United Kingdom
| | | | - Christos Zikos
- National Center for Scientific Research "Demokritos," Aghia Paraskevi, Greece
| | - Evangelia Livaniou
- National Center for Scientific Research "Demokritos," Aghia Paraskevi, Greece
| | - Nazar Amso
- Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - George Nounesis
- National Center for Scientific Research "Demokritos," Aghia Paraskevi, Greece
| | - Karl Swann
- Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom
| | - F Anthony Lai
- Cardiff University School of Medicine, Heath Park, Cardiff, United Kingdom.
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Swann K, Lai FA. PLC? and the initiation of Ca2+ oscillations in fertilizing mammalian eggs. Cell Calcium 2013; 53:55-62. [DOI: 10.1016/j.ceca.2012.11.001] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2012] [Revised: 10/31/2012] [Accepted: 11/01/2012] [Indexed: 10/27/2022]
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Abstract
Phospholipase C (PLC) converts phosphatidylinositol 4,5-bisphosphate (PIP(2)) to inositol 1,4,5-trisphosphate (IP(3)) and diacylglycerol (DAG). DAG and IP(3) each control diverse cellular processes and are also substrates for synthesis of other important signaling molecules. PLC is thus central to many important interlocking regulatory networks. Mammals express six families of PLCs, each with both unique and overlapping controls over expression and subcellular distribution. Each PLC also responds acutely to its own spectrum of activators that includes heterotrimeric G protein subunits, protein tyrosine kinases, small G proteins, Ca(2+), and phospholipids. Mammalian PLCs are autoinhibited by a region in the catalytic TIM barrel domain that is the target of much of their acute regulation. In combination, the PLCs act as a signaling nexus that integrates numerous signaling inputs, critically governs PIP(2) levels, and regulates production of important second messengers to determine cell behavior over the millisecond to hour timescale.
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Affiliation(s)
- Ganesh Kadamur
- Department of Pharmacology, Molecular Biophysics Graduate Program and Green Center for Systems Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
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Bedford-Guaus SJ, McPartlin LA, Varner DD. Characterization of Equine Phospholipase C Zeta: A Review and Preliminary Results on Expression Defects in Subfertile Stallions. J Equine Vet Sci 2012. [DOI: 10.1016/j.jevs.2012.06.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Ramadan WM, Kashir J, Jones C, Coward K. Oocyte activation and phospholipase C zeta (PLCζ): diagnostic and therapeutic implications for assisted reproductive technology. Cell Commun Signal 2012; 10:12. [PMID: 22591604 PMCID: PMC3393615 DOI: 10.1186/1478-811x-10-12] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2012] [Accepted: 05/16/2012] [Indexed: 12/18/2022] Open
Abstract
Infertility affects one in seven couples globally and has recently been classified as a disease by the World Health Organisation (WHO). While in-vitro fertilisation (IVF) offers effective treatment for many infertile couples, cases exhibiting severe male infertility (19-57%) often remain difficult, if not impossible to treat. In such cases, intracytoplasmic sperm injection (ICSI), a technique in which a single sperm is microinjected into the oocyte, is implemented. However, 1-5% of ICSI cycles still fail to fertilise, affecting over 1000 couples per year in the UK alone. Pregnancy and delivery rates for IVF and ICSI rarely exceed 30% and 23% respectively. It is therefore imperative that Assisted Reproductive Technology (ART) protocols are constantly modified by associated research programmes, in order to provide patients with the best chances of conception. Prior to fertilisation, mature oocytes are arrested in the metaphase stage of the second meiotic division (MII), which must be alleviated to allow the cell cycle, and subsequent embryogenesis, to proceed. Alleviation occurs through a series of concurrent events, collectively termed 'oocyte activation'. In mammals, oocytes are activated by a series of intracellular calcium (Ca2+) oscillations following gamete fusion. Recent evidence implicates a sperm-specific phospholipase C, PLCzeta (PLCζ), introduced into the oocyte following membrane fusion as the factor responsible. This review summarises our current understanding of oocyte activation failure in human males, and describes recent advances in our knowledge linking certain cases of male infertility with defects in PLCζ expression and activity. Systematic literature searches were performed using PubMed and the ISI-Web of Knowledge. Databases compiled by the United Nations and World Health Organisation databases (UNWHO), and the Human Fertilization and Embryology Authority (HFEA) were also scrutinised. It is clear that PLCζ plays a fundamental role in the activation of mammalian oocytes, and that genetic, molecular, or biochemical perturbation of this key enzyme is strongly linked to human infertility where oocyte activation is deficient. Consequently, there is significant scope for our understanding of PLCζ to be translated to the ART clinic, both as a novel therapeutic agent with which to rescue oocyte activation deficiency (OAD), or as a prognostic/diagnostic biomarker of oocyte activation ability in target sperm samples.
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Affiliation(s)
- Walaa M Ramadan
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women’s Centre, John Radcliffe Hospital, Headington, Oxford, OX3, 9DU, UK
| | - Junaid Kashir
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women’s Centre, John Radcliffe Hospital, Headington, Oxford, OX3, 9DU, UK
| | - Celine Jones
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women’s Centre, John Radcliffe Hospital, Headington, Oxford, OX3, 9DU, UK
| | - Kevin Coward
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women’s Centre, John Radcliffe Hospital, Headington, Oxford, OX3, 9DU, UK
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Goñi FM, Montes LR, Alonso A. Phospholipases C and sphingomyelinases: Lipids as substrates and modulators of enzyme activity. Prog Lipid Res 2012; 51:238-66. [DOI: 10.1016/j.plipres.2012.03.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 03/23/2012] [Accepted: 03/26/2012] [Indexed: 11/30/2022]
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Yoon SY, Eum JH, Lee JE, Lee HC, Kim YS, Han JE, Won HJ, Park SH, Shim SH, Lee WS, Fissore RA, Lee DR, Yoon TK. Recombinant human phospholipase C zeta 1 induces intracellular calcium oscillations and oocyte activation in mouse and human oocytes. Hum Reprod 2012; 27:1768-80. [PMID: 22456923 DOI: 10.1093/humrep/des092] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Oocyte activation is a crucial step that comprises the release of the oocyte from meiotic arrest, pronuclear formation and subsequent embryo development. Oocytes are activated by repetitive increases in the intracellular concentration of free Ca(2+), [Ca(2+)](i) oscillations, which are triggered during fertilization by the introduction of the sperm-specific phospholipase C zeta 1 (PLCZ1). Recent studies have shown that sperm from patients lacking expression of PLCZ1 or expressing mutant forms of PLCZ1 fail to induce [Ca(2+)](i) oscillations or oocyte activation. We first purified recombinant human PLCZ1 (hPLCZ1) protein and evaluated its [Ca(2+)](i) oscillation activity in mouse and human oocytes with the view to investigate its application in the clinic for assisted oocytes activation in lieu of chemical agents. METHODS Recombinant hPLCZ1 was synthesized using the Escherichia coli system, and subjected to immunoblot analysis with anti-PLCZ1 and anti-His tag antibodies. [Ca(2+)](i) oscillations by microinjection of recombinant hPLCZ1 into mouse or human oocytes were examined by [Ca(2+)](i) monitoring with Fluo 4. Ploidy of the oocytes with recombinant hPLCZ1 injection was confirmed with fluorescence in situ hybridization. RESULTS A band of 68 kDa on recombinant protein was detected with both antibodies. Injection of recombinant hPLCZ1 induced [Ca(2+)](i) oscillations in a dose-dependent manner in both mouse and human oocytes. These oscillations, which closely resembled those initiated by the sperm upon fertilization, triggered activation and cleavage in oocytes of both species, although further development of the mice embryos was low. U73122, a PLC inhibitor, blocked the ability of hPLCZ1 to initiate oscillations. Microinjection of recombinant hPLCZ1 into ICSI-failed human oocytes rescued fertilization failure in five of eight attempts. CONCLUSIONS Repeated [Ca(2+)](i) oscillations and oocyte activation were induced in mouse and human oocytes by microinjection of recombinant hPLCZ1 synthesized in E. Coli. Injection of recombinant protein could thus provide a biological solution for inducing artificial activation of oocytes.
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Affiliation(s)
- Sook-Young Yoon
- Fertility Center of CHA Gangnam Medical Center, CHA University, Gangnam-gu, Seoul, Republic of Korea
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Kiselev VY, Leda M, Lobanov AI, Marenduzzo D, Goryachev AB. Lateral dynamics of charged lipids and peripheral proteins in spatially heterogeneous membranes: comparison of continuous and Monte Carlo approaches. J Chem Phys 2012; 135:155103. [PMID: 22029337 DOI: 10.1063/1.3652958] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Biological membranes are complex environments whose physico-chemical properties are of utmost importance for the understanding of many crucial biological processes. Much attention has been given in the literature to the description of membranes along the z-axis perpendicular to the membrane. Here, we instead consider the lateral dynamics of lipids and peripheral proteins due to their electrostatic interaction. Previously, we constructed a Monte Carlo automaton capable of simulating mutual diffusive dynamics of charged lipids and associated positively charged peptides. Here, we derive and numerically analyze a system of Poisson-Boltzmann-Nernst-Planck (PBNP) equations that provide a mean-field approximation compatible with our Monte Carlo model. The thorough comparison between the mean-field PBNP equations and Monte Carlo simulations demonstrates that both the approaches are in a good qualitative agreement in all tested scenarios. We find that the two methods quantitatively deviate when the local charge density is high, presumably because the Poisson-Boltzmann formalism is applicable in the so-called weak coupling limit, whose validity is restricted to low charge densities. Nevertheless, we conclude that the mean-field PBNP approach provides a good approximation for the considerably more detailed Monte Carlo model at only a fraction of the associated computational cost and allows simulation of the membrane lateral dynamics on the space and time scales relevant for the realistic biological problems.
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Affiliation(s)
- Vladimir Yu Kiselev
- Centre for Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom
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Calcium Oscillations, Oocyte Activation, and Phospholipase C zeta. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 740:1095-121. [DOI: 10.1007/978-94-007-2888-2_50] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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Abstract
The physiological effects of many extracellular neurotransmitters, hormones, growth factors, and other stimuli are mediated by receptor-promoted activation of phospholipase C (PLC) and consequential activation of inositol lipid signaling pathways. These signaling responses include the classically described conversion of phosphatidylinositol(4,5)P(2) to the Ca(2+)-mobilizing second messenger inositol(1,4,5)P(3) and the protein kinase C-activating second messenger diacylglycerol as well as alterations in membrane association or activity of many proteins that harbor phosphoinositide binding domains. The 13 mammalian PLCs elaborate a minimal catalytic core typified by PLC-d to confer multiple modes of regulation of lipase activity. PLC-b isozymes are activated by Gaq- and Gbg-subunits of heterotrimeric G proteins, and activation of PLC-g isozymes occurs through phosphorylation promoted by receptor and non-receptor tyrosine kinases. PLC-e and certain members of the PLC-b and PLC-g subclasses of isozymes are activated by direct binding of small G proteins of the Ras, Rho, and Rac subfamilies of GTPases. Recent high resolution three dimensional structures together with biochemical studies have illustrated that the X/Y linker region of the catalytic core mediates autoinhibition of most if not all PLC isozymes. Activation occurs as a consequence of removal of this autoinhibition.
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48
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Yu Y, Nomikos M, Theodoridou M, Nounesis G, Lai FA, Swann K. PLCζ causes Ca(2+) oscillations in mouse eggs by targeting intracellular and not plasma membrane PI(4,5)P(2). Mol Biol Cell 2012; 23:371-80. [PMID: 22114355 PMCID: PMC3258180 DOI: 10.1091/mbc.e11-08-0687] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 10/31/2011] [Accepted: 11/16/2011] [Indexed: 01/10/2023] Open
Abstract
Sperm-specific phospholipase C ζ (PLCζ) activates embryo development by triggering intracellular Ca(2+) oscillations in mammalian eggs indistinguishable from those at fertilization. Somatic PLC isozymes generate inositol 1,4,5-trisphophate-mediated Ca(2+) release by hydrolyzing phosphatidylinositol 4,5-bisphosphate (PI(4,5)P(2)) in the plasma membrane. Here we examine the subcellular source of PI(4,5)P(2) targeted by sperm PLCζ in mouse eggs. By monitoring egg plasma membrane PI(4,5)P(2) with a green fluorescent protein-tagged PH domain, we show that PLCζ effects minimal loss of PI(4,5)P(2) from the oolemma in contrast to control PLCδ1, despite the much higher potency of PLCζ in eliciting Ca(2+) oscillations. Specific depletion of this PI(4,5)P(2) pool by plasma membrane targeting of an inositol polyphosphate-5-phosphatase (Inp54p) blocked PLCδ1-mediated Ca(2+) oscillations but not those stimulated by PLCζ or sperm. Immunolocalization of PI(4,5)P(2), PLCζ, and catalytically inactive PLCζ (ciPLCζ) revealed their colocalization to distinct vesicular structures inside the egg cortex. These vesicles displayed decreased PI(4,5)P(2) after PLCζ injection. Targeted depletion of vesicular PI(4,5)P(2) by expression of ciPLCζ-fused Inp54p inhibited the Ca(2+) oscillations triggered by PLCζ or sperm but failed to affect those mediated by PLCδ1. In contrast to somatic PLCs, our data indicate that sperm PLCζ induces Ca(2+) mobilization by hydrolyzing internal PI(4,5)P(2) stores, suggesting that the mechanism of mammalian fertilization comprises a novel phosphoinositide signaling pathway.
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Affiliation(s)
- Yuansong Yu
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Michail Nomikos
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, United Kingdom
- National Center for Scientific Research Demokritos, 15310 Aghia Paraskevi, Greece
| | - Maria Theodoridou
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, United Kingdom
- National Center for Scientific Research Demokritos, 15310 Aghia Paraskevi, Greece
| | - George Nounesis
- National Center for Scientific Research Demokritos, 15310 Aghia Paraskevi, Greece
| | - F. Anthony Lai
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, United Kingdom
| | - Karl Swann
- Institute of Molecular and Experimental Medicine, Cardiff University School of Medicine, Cardiff CF14 4XN, United Kingdom
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Shin JJH, Loewen CJR. Putting the pH into phosphatidic acid signaling. BMC Biol 2011; 9:85. [PMID: 22136116 PMCID: PMC3229452 DOI: 10.1186/1741-7007-9-85] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Accepted: 12/02/2011] [Indexed: 01/03/2023] Open
Abstract
The lipid phosphatidic acid (PA) has important roles in cell signaling and metabolic regulation in all organisms. New evidence indicates that PA also has an unprecedented role as a pH biosensor, coupling changes in pH to intracellular signaling pathways. pH sensing is a property of the phosphomonoester headgroup of PA. A number of other potent signaling lipids also contain headgroups with phosphomonoesters, implying that pH sensing by lipids may be widespread in biology.
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Affiliation(s)
- John J H Shin
- Department of Cellular and Physiological Sciences, Life Sciences Institute, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, Canada, V6T 1Z3
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50
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Abstract
The XY-linker region of somatic cell PLC (phospholipase)-β, -γ, -δ and -ε isoforms confers potent catalytic inhibition, suggesting a common auto-regulatory role. Surprisingly, the sperm PLCζ XY-linker does not mediate auto-inhibition. Unlike for somatic PLCs, the absence of the PLCζ XY-linker significantly diminishes both in vitro PIP2 (phosphatidylinositol 4,5-bisphosphate) hydrolysis and in vivo Ca2+-oscillation-inducing activity, revealing evidence for a novel PLCζ enzymatic mechanism.
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