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Bueno VLC, Bastos HBDA, Centeno LA, Kretzmann NA, Mattos RC, Rechsteiner SF. PLCζ, WBP2NL and TNF-α expression in spermatozoa is associated with stallion fertility and seminal quality? Anim Reprod 2024; 21:e20230088. [PMID: 38628496 PMCID: PMC11019795 DOI: 10.1590/1984-3143-ar2023-0088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 02/19/2024] [Indexed: 04/19/2024] Open
Abstract
This study aims to investigate the gene expression of sperm-borne phospholipase C zeta (PLCζ), WW domain-binding protein 2N-Terminal Like (WBP2NL), and Tumor necrosis factor (TNF-α), as a negative control, in spermatozoa and their relationship with fertility and seminal quality in stallions. Ejaculates from 40 Criollo stallions were used, whose fertility was assessed on the basis of their pregnancy rate per cycle in at least two breeding seasons. Pregnancy rates ranged from 20% to 90% and were used to divide the stallions into two groups: High rates (≥ 50%) (n = 25), and Low rates (< 50%) (n = 15). A computer-assisted sperm analysis system - (CASA) analyzed semen after collection. Also were evaluated the physical and functional integrity of the plasmatic membrane and sperm morphology alterations. All stallions expressed PLCζ, WBP2NL, and TNF-α. PLCζ positively correlates with conception rate, total motility (TM), progressive motility (PM), plasmatic membrane functionality, and integrity. A simple linear regression was detected between pregnancy rate and PLCζ expression (P = 0.003), TM (P < 0.001) and PM (P < 0.001). PLCζ gene expression was higher (P = 0,012) in the High rates group than in the Low group. WBP2NL and TNF-α did not correlate with seminal quality and stallion's fertility. It was concluded that PLCζ gene expression in the spermatozoa might be used as a biomarker of fertility and seminal quality in stallions. Parameters of sperm kinetics also showed, positive correlation between TM, PM and pregnancy rate.
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Affiliation(s)
- Verônica La Cruz Bueno
- Histologia e Reprodução Equina, Departamento de Morfologia, Instituto de Biologia, Universidade Federal de Pelotas, Pelotas, RS, Brasil
- Laboratório de Reprodução Animal, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
| | | | - Luiz Augusto Centeno
- Laboratório de Reprodução Animal, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
| | | | - Rodrigo Costa Mattos
- Laboratório de Reprodução Animal, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
| | - Sandra Fiala Rechsteiner
- Histologia e Reprodução Equina, Departamento de Morfologia, Instituto de Biologia, Universidade Federal de Pelotas, Pelotas, RS, Brasil
- Laboratório de Reprodução Animal, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil
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2
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Satouh Y, Sato K. Reorganization, specialization, and degradation of oocyte maternal components for early development. Reprod Med Biol 2023; 22:e12505. [PMID: 36726596 PMCID: PMC9884333 DOI: 10.1002/rmb2.12505] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 01/07/2023] [Accepted: 01/12/2023] [Indexed: 01/30/2023] Open
Abstract
Background Oocyte components are maternally provided, solely determine oocyte quality, and coordinately determine embryo quality with zygotic gene expression. During oocyte maturation, maternal organelles are drastically reorganized and specialized to support oocyte characteristics. A large number of maternal components are actively degraded after fertilization and gradually replaced by zygotic gene products. The molecular basis and the significance of these processes on oocyte/embryo quality are not fully understood. Methods Firstly, recent findings in organelle characteristics of other cells or oocytes from model organisms are introduced for further understanding of oocyte organelle reorganization/specialization. Secondly, recent progress in studies on maternal components degradation and their molecular mechanisms are introduced. Finally, future applications of these advancements for predicting mammalian oocyte/embryo quality are discussed. Main findings The significance of cellular surface protein degradation via endocytosis for embryonic development, and involvement of biogenesis of lipid droplets in embryonic quality, were recently reported using mammalian model organisms. Conclusion Identifying key oocyte component characteristics and understanding their dynamics may lead to new applications in oocyte/embryo quality prediction and improvement. To implement these multidimensional concepts, development of new technical approaches that allow us to address the complexity and efficient studies using model organisms are required.
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Affiliation(s)
- Yuhkoh Satouh
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular RegulationGunma UniversityMaebashiJapan
| | - Ken Sato
- Laboratory of Molecular Traffic, Institute for Molecular and Cellular RegulationGunma UniversityMaebashiJapan
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3
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Zhang XZ, Wei LL, Zhang XH, Jin HJ, Chen SR. Loss of perinuclear theca ACTRT1 causes acrosome detachment and severe male subfertility in mice. Development 2022; 149:275523. [DOI: 10.1242/dev.200489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 05/12/2022] [Indexed: 11/20/2022]
Abstract
ABSTRACT
The perinuclear theca (PT) is a cytoskeletal element encapsulating the sperm nucleus; however, the physiological roles of the PT in sperm are largely uncertain. Here, we reveal that ACTRT1, ACTRT2, ACTL7A and ACTL9 proteins interact to form a multimeric complex and localize to the subacrosomal region of spermatids. Furthermore, we engineered Actrt1-knockout (KO) mice to define the functions of ACTRT1. Despite normal sperm count and motility, Actrt1-KO males were severely subfertile owing to a deficiency in fertilization. Loss of ACTRT1 caused a high incidence of malformed heads and detachment of acrosomes from sperm nuclei, caused by loosened acroplaxome structure during spermiogenesis. Furthermore, Actrt1-KO sperm showed reduced ACTL7A and PLCζ protein content as a potential cause of fertilization defects. Moreover, we reveal that ACTRT1 anchors developing acrosomes to the nucleus, likely by interacting with the inner acrosomal membrane protein SPACA1 and the nuclear envelope proteins PARP11 and SPATA46. Loss of ACTRT1 weakened the interaction between ACTL7A and SPACA1. Our study and recent findings of ACTL7A/ACTL9-deficient sperm together reveal that the sperm PT-specific ARP complex mediates the acrosome-nucleus connection.
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Affiliation(s)
- Xiao-Zhen Zhang
- Ministry of Education, Department of Biology, College of Life Sciences Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
- Beijing Normal University Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
| | - Lin-Lin Wei
- Ministry of Education, Department of Biology, College of Life Sciences Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
- Beijing Normal University Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
| | - Xiao-Hui Zhang
- Ministry of Education, Department of Biology, College of Life Sciences Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
- Beijing Normal University Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
| | - Hui-Juan Jin
- Ministry of Education, Department of Biology, College of Life Sciences Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
- Beijing Normal University Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
| | - Su-Ren Chen
- Ministry of Education, Department of Biology, College of Life Sciences Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
- Beijing Normal University Key Laboratory of Cell Proliferation and Regulation Biology , , , 100875 Beijing , China
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4
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Yanagimachi R. Mysteries and unsolved problems of mammalian fertilization and related topics. Biol Reprod 2022; 106:644-675. [PMID: 35292804 PMCID: PMC9040664 DOI: 10.1093/biolre/ioac037] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2021] [Revised: 02/10/2022] [Accepted: 02/10/2022] [Indexed: 11/13/2022] Open
Abstract
Mammalian fertilization is a fascinating process that leads to the formation of a new individual. Eggs and sperm are complex cells that must meet at the appropriate time and position within the female reproductive tract for successful fertilization. I have been studying various aspects of mammalian fertilization over 60 years. In this review, I discuss many different aspects of mammalian fertilization, some of my laboratory's contribution to the field, and discuss enigmas and mysteries that remain to be solved.
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Affiliation(s)
- Ryuzo Yanagimachi
- Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, University of Hawaii Medical School, Honolulu, HI 96822, USA
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5
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Shafqat A, Kashir J, Alsalameh S, Alkattan K, Yaqinuddin A. Fertilization, Oocyte Activation, Calcium Release and Epigenetic Remodelling: Lessons From Cancer Models. Front Cell Dev Biol 2022; 10:781953. [PMID: 35309905 PMCID: PMC8931327 DOI: 10.3389/fcell.2022.781953] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2021] [Accepted: 02/14/2022] [Indexed: 12/11/2022] Open
Abstract
Oocyte activation deficiency (OAD) is the basis of Total Fertilisation Failure (TFF) and is attributed to mutations in the PLCζ gene—termed male factor infertility. This derives abnormal Ca2+ oscillations and could be the main cause of primary disruptions in the gene expression of Ca2+-related proteins. Epigenetic mechanisms are universally accepted as key regulators of gene expression. However, epigenetic dysregulations have not been considered as potential mechanisms of oocyte-borne OAD. Herein, we discuss changes in the DNA methylome during oogenesis and embryogenesis. We further highlight key pathways comprising the oocyte Ca2+ toolkit, which could be targets of epigenetic alterations, especially aberrations in DNA methylation. Considering that the vast majority of epigenetic modifications examined during fertilization revolve around alterations in DNA methylation, we aim in this article to associate Ca2+-specific mechanisms with these alterations. To strengthen this perspective, we bring evidence from cancer research on the intricate link between DNA methylation and Ca2+ signaling as cancer research has examined such questions in a lot more detail. From a therapeutic standpoint, if our hypothesis is proven to be correct, this will explain the cause of TFF in idiopathic cases and will open doors for novel therapeutic targets.
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Affiliation(s)
- Areez Shafqat
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Junaid Kashir
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
- Department of Comparative Medicine, King Faisal Specialist Hospital and Research Center, Riyadh, Saudi Arabia
| | | | - Khaled Alkattan
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
| | - Ahmed Yaqinuddin
- College of Medicine, Alfaisal University, Riyadh, Saudi Arabia
- *Correspondence: Ahmed Yaqinuddin,
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6
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Özbek M, Hitit M, Kaya A, Jousan FD, Memili E. Sperm Functional Genome Associated With Bull Fertility. Front Vet Sci 2021; 8:610888. [PMID: 34250055 PMCID: PMC8262648 DOI: 10.3389/fvets.2021.610888] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Accepted: 05/05/2021] [Indexed: 01/08/2023] Open
Abstract
Bull fertility is an important economic trait in sustainable cattle production, as infertile or subfertile bulls give rise to large economic losses. Current methods to assess bull fertility are tedious and not totally accurate. The massive collection of functional data analyses, including genomics, proteomics, metabolomics, transcriptomics, and epigenomics, helps researchers generate extensive knowledge to better understand the unraveling physiological mechanisms underlying subpar male fertility. This review focuses on the sperm phenomes of the functional genome and epigenome that are associated with bull fertility. Findings from multiple sources were integrated to generate new knowledge that is transferable to applied andrology. Diverse methods encompassing analyses of molecular and cellular dynamics in the fertility-associated molecules and conventional sperm parameters can be considered an effective approach to determine bull fertility for efficient and sustainable cattle production. In addition to gene expression information, we also provide methodological information, which is important for the rigor and reliability of the studies. Fertility is a complex trait influenced by several factors and has low heritability, although heritability of scrotal circumference is high and that it is a known fertility maker. There is a need for new knowledge on the expression levels and functions of sperm RNA, proteins, and metabolites. The new knowledge can shed light on additional fertility markers that can be used in combination with scrotal circumference to predict the fertility of breeding bulls. This review provides a comprehensive review of sperm functional characteristics or phenotypes associated with bull fertility.
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Affiliation(s)
- Memmet Özbek
- Department of Histology and Embryology, Faculty of Veterinary Medicine, Burdur Mehmet Akif Ersoy University, Burdur, Turkey
| | - Mustafa Hitit
- Department of Genetics, Faculty of Veterinary Medicine, Kastamonu University, Kastamonu, Turkey
| | - Abdullah Kaya
- Department of Artificial Insemination and Reproduction, Faculty of Veterinary Medicine, Selcuk University, Konya, Turkey
| | - Frank Dean Jousan
- Department of Animal and Dairy Sciences, Mississippi State University, Starkville, MS, United States
| | - Erdogan Memili
- Department of Animal and Dairy Sciences, Mississippi State University, Starkville, MS, United States
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7
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Niu CM, Xia MM, Zhong YN, Zheng Y. Mus musculus Barrier-To-Autointegration Factor 2 (Banf2) is Not Essential for Spermatogenesis or Fertility. Cytogenet Genome Res 2021; 161:167-177. [PMID: 33951625 DOI: 10.1159/000513850] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Accepted: 12/16/2020] [Indexed: 11/19/2022] Open
Abstract
The barrier-to-autointegration factor (BAF) is widely expressed in most human tissues and plays a critical role in chromatin organization, nuclear envelope assembly, gonadal development, and embryonic stem cell self-renewal. Complete loss of BAF has been shown to lead to embryonic lethality and gonadal defects. The BAF paralog, namely, barrier-to-autointegration factor 2 (BANF2), exhibits a testis-predominant expression pattern in both humans and mice. Unlike BAF, it may cause isolated male infertility. Therefore, we used the CRISPR/Cas9 system to generate Banf2-knockout mice to further study its function in spermatogenesis. Unexpectedly, knockout mice did not show any detectable abnormalities in histological structure of the testis, epididymis, ovary, and other tissues, and exhibited normal fertility, indicating that Banf2 is not essential for mouse spermatogenesis and fertility.
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Affiliation(s)
- Chang-Min Niu
- Department of Histology and Embryology, School of Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Experimental and Translational Noncoding RNA Research, Yangzhou, China
| | - Meng-Meng Xia
- Department of Histology and Embryology, School of Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Experimental and Translational Noncoding RNA Research, Yangzhou, China
| | - Ya-Nan Zhong
- Department of Histology and Embryology, School of Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Experimental and Translational Noncoding RNA Research, Yangzhou, China
| | - Ying Zheng
- Department of Histology and Embryology, School of Medicine, Yangzhou University, Yangzhou, China
- Jiangsu Key Laboratory of Experimental and Translational Noncoding RNA Research, Yangzhou, China
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8
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Zafar MI, Lu S, Li H. Sperm-oocyte interplay: an overview of spermatozoon's role in oocyte activation and current perspectives in diagnosis and fertility treatment. Cell Biosci 2021; 11:4. [PMID: 33407934 PMCID: PMC7789549 DOI: 10.1186/s13578-020-00520-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 12/15/2020] [Indexed: 02/07/2023] Open
Abstract
The fertilizing spermatozoon is a highly specialized cell that selects from millions along the female tract until the oocyte. The paternal components influence the oocyte activation during fertilization and are fundamental for normal embryo development; however, the sperm-oocyte interplay is in a continuous debate. This review aims to analyze the available scientific information related to the role of the male gamete in the oocyte activation during fertilization, the process of the interaction of sperm factors with oocyte machinery, and the implications of any alterations in this interplay, as well as the advances and limitations of the reproductive techniques and diagnostic tests. At present, both PLCζ and PAWP are the main candidates as oocyte activated factors during fertilization. While PLCζ mechanism is via IP3, how PAWP activates the oocyte still no clear, and these findings are important to study and treat fertilization failure due to oocyte activation, especially when one of the causes is the deficiency of PLCζ in the sperm. However, no diagnostic test has been developed to establish the amount of PLCζ, the protocol to treat this type of pathologies is broad, including treatment with ionophores, sperm selection improvement, and microinjection with PLCζ protein or RNA.
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Affiliation(s)
- Mohammad Ishraq Zafar
- Institute of Reproductive Health/Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, 13 Hang Kong Road, Wuhan, 430030, People's Republic of China
| | - Shi Lu
- Department of Obstetrics and Gynecology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, 1277 Jeifang Avenue, Wuhan, 430022, People's Republic of China
| | - Honggang Li
- Institute of Reproductive Health/Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, 13 Hang Kong Road, Wuhan, 430030, People's Republic of China. .,Wuhan Tongji Reproductive Medicine Hospital, 128 Sanyang Road, Wuhan, 430013, People's Republic of China.
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9
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Diagnosis and Treatment of Male Infertility-Related Fertilization Failure. J Clin Med 2020; 9:jcm9123899. [PMID: 33271815 PMCID: PMC7761017 DOI: 10.3390/jcm9123899] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/22/2022] Open
Abstract
Infertility affects approximately 15% of reproductive-aged couples worldwide, of which up to 30% of the cases are caused by male factors alone. The origin of male infertility is mostly attributed to sperm abnormalities, of which many are caused by genetic defects. The development of intracytoplasmic sperm injection (ICSI) has helped to circumvent most male infertility conditions. However, there is still a challenging group of infertile males whose sperm, although having normal sperm parameters, are unable to activate the oocyte, even after ICSI treatment. While ICSI generally allows fertilization rates of 70 to 80%, total fertilization failure (FF) still occurs in 1 to 3% of ICSI cycles. Phospholipase C zeta (PLCζ) has been demonstrated to be a critical sperm oocyte activating factor (SOAF) and the absence, reduced, or altered forms of PLCζ have been shown to cause male infertility-related FF. The purpose of this review is to (i) summarize the current knowledge on PLCζ as the critical sperm factor for successful fertilization, as well as to discuss the existence of alternative sperm-induced oocyte activation mechanisms, (ii) describe the diagnostic tests available to determine the cause of FF, and (iii) summarize the beneficial effect of assisted oocyte activation (AOA) to overcome FF.
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10
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Gonzalez-Castro RA, Amoroso-Sanches F, Stokes JE, Graham JK, Carnevale EM. Localisation of phospholipase Cζ1 (PLCZ1) and postacrosomal WW-binding protein (WBP2 N-terminal like) on equine spermatozoa and flow cytometry quantification of PLCZ1 and association with cleavage in vitro. Reprod Fertil Dev 2020; 31:1778-1792. [PMID: 31597592 DOI: 10.1071/rd19217] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2019] [Accepted: 09/03/2019] [Indexed: 02/01/2023] Open
Abstract
Oocyte activation is initiated when a fertilising spermatozoon delivers sperm-borne oocyte-activating factor(s) into the oocyte cytoplasm. Candidates for oocyte activation include two proteins, phospholipase Cζ1 (PLCZ1) and postacrosomal WW-binding protein (PAWP; also known as WBP2 N-terminal like (WBP2NL)). We localised PLCZ1 and WBP2NL/PAWP in stallion spermatozoa and investigated the PLCZ1 content and sperm parameters as well as cleavage after intracytoplasmic sperm injection (ICSI). PLCZ1 was identified as 71-kDa protein in the acrosomal and postacrosomal regions, midpiece and principal piece of the tail. Anti-WBP2NL antibody identified two WBP2NL bands (~28 and ~32kDa) in the postacrosomal region, midpiece and principal piece of the tail. PLCZ1 and WBP2NL expression was positively correlated (P=0.04) in sperm heads. Flow cytometry evaluation of PLCZ1 revealed large variations in fluorescence intensity and the percentage of positively labelled spermatozoa among stallions. PLCZ1 expression was significantly higher in viable than non-viable spermatozoa, and DNA fragmentation was negatively correlated with PLCZ1 expression and the percentage of positively labelled spermatozoa (P<0.05). The use of equine sperm populations considered to have high versus low PLCZ1 content resulted in significantly higher cleavage rates after ICSI of bovine and equine oocytes, supporting the importance of PLCZ1 for oocyte activation.
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Affiliation(s)
- Raul A Gonzalez-Castro
- Equine Reproduction Laboratory, Department of Biomedical Sciences, Colorado State University, 3101 Rampart Rd, Fort Collins, Colorado, 80521, USA
| | - Fabio Amoroso-Sanches
- Equine Reproduction Laboratory, Department of Biomedical Sciences, Colorado State University, 3101 Rampart Rd, Fort Collins, Colorado, 80521, USA
| | - JoAnne E Stokes
- Equine Reproduction Laboratory, Department of Biomedical Sciences, Colorado State University, 3101 Rampart Rd, Fort Collins, Colorado, 80521, USA
| | - James K Graham
- Equine Reproduction Laboratory, Department of Biomedical Sciences, Colorado State University, 3101 Rampart Rd, Fort Collins, Colorado, 80521, USA
| | - Elaine M Carnevale
- Equine Reproduction Laboratory, Department of Biomedical Sciences, Colorado State University, 3101 Rampart Rd, Fort Collins, Colorado, 80521, USA; and Corresponding author.
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11
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Nakai M, Ito J, Suyama A, Kageyama A, Tobari Y, Kashiwazaki N. Phospholipase Cζ (PLCζ) versus postacrosomal sheath WW domain-binding protein (PAWP): Which molecule will survive as a sperm factor? Anim Sci J 2020; 91:e13345. [PMID: 32219949 PMCID: PMC7140179 DOI: 10.1111/asj.13345] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 12/26/2019] [Accepted: 12/27/2019] [Indexed: 11/27/2022]
Abstract
During mammalian fertilization, sperm is fused with the oocyte's membrane, triggering the resumption of meiosis from the metaphase II arrest, the extrusion of the second polar body, and the exocytosis of cortical granules; these events are collectively called 'oocyte activation.' In all species studied to date, the transient rise in the cytosolic level of calcium (in particular, the repeated calcium increases called 'calcium oscillations' in mammals) is required for these events. Researchers have focused on identifying the factor(s) that can induce calcium oscillations during fertilization. Sperm‐specific phospholipase C, i.e., PLC zeta (PLCζ), is a strong candidate of the factor(s), and several research groups using different species obtained evidence that PLCζ is a sperm factor that can induce calcium oscillations during fertilization. However, postacrosomal sheath Tryptophan‐Tryptophan (WW)—domain‐binding protein (PAWP) was recently shown to have a pivotal role in inducing calcium oscillations in some species. In this review, we focus on PLCζ and PAWP as sperm factors, and we discuss this controversy: Which of these two molecules survives as a sperm factor?
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Affiliation(s)
- Michiko Nakai
- Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Junya Ito
- Laboratory of Animal Reproduction, School of Veterinary Medicine, Azabu University, Sagamihara, Japan.,Graduate School of Veterinary Sciences, Azabu University, Sagamihara, Japan
| | - Ayumi Suyama
- Graduate School of Veterinary Sciences, Azabu University, Sagamihara, Japan
| | - Atsuko Kageyama
- Graduate School of Veterinary Sciences, Azabu University, Sagamihara, Japan
| | - Yasuko Tobari
- Laboratory of Animal Genetics and Breeding, School of Veterinary Medicine, Azabu University, Sagamihara, Japan
| | - Naomi Kashiwazaki
- Laboratory of Animal Reproduction, School of Veterinary Medicine, Azabu University, Sagamihara, Japan.,Graduate School of Veterinary Sciences, Azabu University, Sagamihara, Japan
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12
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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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13
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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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14
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Abstract
Phospholipase C (PLC) family members constitute a family of diverse enzymes. Thirteen different family members have been cloned. These family members have unique structures that mediate various functions. Although PLC family members all appear to signal through the bi-products of cleaving phospholipids, it is clear that each family member, and at times each isoform, contributes to unique cellular functions. This chapter provides a review of the current literature on PLC. In addition, references have been provided for more in-depth information regarding areas that are not discussed including tyrosine kinase activation of PLC. Understanding the roles of the individual PLC enzymes, and their distinct cellular functions, will lead to a better understanding of the physiological roles of these enzymes in the development of diseases and the maintenance of homeostasis.
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15
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Wakai T, Mehregan A, Fissore RA. Ca 2+ Signaling and Homeostasis in Mammalian Oocytes and Eggs. Cold Spring Harb Perspect Biol 2019; 11:a035162. [PMID: 31427376 PMCID: PMC6886447 DOI: 10.1101/cshperspect.a035162] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Changes in the intracellular concentration of calcium ([Ca2+]i) represent a vital signaling mechanism enabling communication between and among cells as well as with the environment. Cells have developed a sophisticated set of molecules, "the Ca2+ toolkit," to adapt [Ca2+]i changes to specific cellular functions. Mammalian oocytes and eggs, the subject of this review, are not an exception, and in fact the initiation of embryo devolvement in all species is entirely dependent on distinct [Ca2+]i responses. Here, we review the components of the Ca2+ toolkit present in mammalian oocytes and eggs, the regulatory mechanisms that allow these cells to accumulate Ca2+ in the endoplasmic reticulum, release it, and maintain basal and stable cytoplasmic concentrations. We also discuss electrophysiological and genetic studies that have uncovered Ca2+ influx channels in oocytes and eggs, and we analyze evidence supporting the role of a sperm-specific phospholipase C isoform as the trigger of Ca2+ oscillations during mammalian fertilization including its implication in fertility.
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Affiliation(s)
- Takuya Wakai
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003
| | - Aujan Mehregan
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003
| | - Rafael A Fissore
- Department of Veterinary and Animal Sciences, University of Massachusetts Amherst, Amherst, Massachusetts 01003
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16
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Hamilton LE, Suzuki J, Acteau G, Shi M, Xu W, Meinsohn MC, Sutovsky P, Oko R. WBP2 shares a common location in mouse spermatozoa with WBP2NL/PAWP and like its descendent is a candidate mouse oocyte-activating factor. Biol Reprod 2019; 99:1171-1183. [PMID: 30010725 PMCID: PMC6299249 DOI: 10.1093/biolre/ioy156] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 07/12/2018] [Indexed: 11/19/2022] Open
Abstract
The sperm-borne oocyte-activating factor (SOAF) resides in the sperm perinuclear theca (PT). A consensus has been reached that SOAF most likely resides in the postacrosomal sheath (PAS), which is the first region of the PT to solubilize upon sperm–oocyte fusion. There are two SOAF candidates under consideration: PLCZ1 and WBP2NL. A mouse gene germline ablation of the latter showed that mice remain fertile with no observable phenotype despite the fact that a competitive inhibitor of WBP2NL, derived from its PPXY motif, blocks oocyte activation when coinjected with WBP2NL or spermatozoa. This suggested that the ortholog of WBP2NL, WBP2, containing the same domain and motifs associated with WBP2NL function, might compensate for its deficiency in oocyte activation. Our objectives were to examine whether WBP2 meets the developmental criteria established for SOAF and whether it has oocyte-activating potential. Immunoblotting detected WBP2 in mice testis and sperm and immunofluorescence localized WBP2 to the PAS and perforatorium of the PT. Immunohistochemistry of the testes revealed that WBP2 reactivity was highest in round spermatids and immunofluorescence detected WBP2 in the cytoplasmic lobe of elongating spermatids and colocalized it with the microtubular manchette during PT assembly. Microinjection of the recombinant forms of WBP2 and WBP2NL into metaphase II mouse oocytes resulted in comparable rates of oocyte activation. This study shows that WBP2 shares a similar testicular developmental pattern and location with WBP2NL and a shared ability to activate the oocyte, supporting its consideration as a mouse SOAF component that can compensate for a WBP2NL.
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Affiliation(s)
- Lauren E Hamilton
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Joao Suzuki
- Centre de recherche en reproduction fertilité, Faculté de médecine vétérinaire, Université de Montréal, St. Hyacinthe, Quebec, Canada
| | - Genevieve Acteau
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Mengqi Shi
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Wei Xu
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Marie-Charlotte Meinsohn
- Centre de recherche en reproduction fertilité, Faculté de médecine vétérinaire, Université de Montréal, St. Hyacinthe, Quebec, Canada
| | - Peter Sutovsky
- Division of Animal Sciences, College of Food, Agriculture and Natural Resources, University of Missouri, Columbia, Missouri, USA.,Department of Obstetrics, Gynecology and Women's Health, School of Medicine, University of Missouri, Columbia, Missouri, USA
| | - Richard Oko
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
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17
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Mortimer D. The functional anatomy of the human spermatozoon: relating ultrastructure and function. Mol Hum Reprod 2019; 24:567-592. [PMID: 30215807 DOI: 10.1093/molehr/gay040] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2018] [Accepted: 09/11/2018] [Indexed: 12/16/2022] Open
Abstract
The Internet, magazine articles, and even biomedical journal articles, are full of cartoons of spermatozoa that bear minimal resemblance to real spermatozoa, especially human spermatozoa, and this had led to many misconceptions about what spermatozoa look like and how they are constituted. This review summarizes the historical and current state of knowledge of mammalian sperm ultrastructure, with particular emphasis on and relevance to human spermatozoa, combining information obtained from a variety of electron microscopic (EM) techniques. Available information on the composition and configuration of the various ultrastructural components of the spermatozoon has been related to their mechanistic purpose and roles in the primary aspects of sperm function and fertilization: motility, hyperactivation, capacitation, the acrosome reaction and sperm-oocyte fusion.
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Affiliation(s)
- David Mortimer
- Oozoa Biomedical Inc., Caulfeild Village, West Vancouver, BC, Canada
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18
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Parrington J, Arnoult C, Fissore RA. The eggstraordinary story of how life begins. Mol Reprod Dev 2018; 86:4-19. [PMID: 30411426 DOI: 10.1002/mrd.23083] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Accepted: 11/06/2018] [Indexed: 12/24/2022]
Abstract
More than 15 years have elapsed since the identification of phospholipase C ζ1 (PLCζ) from a genomic search for mouse testis/sperm-specific PLCs. This molecule was proposed to represent the sperm factor responsible for the initiation of calcium (Ca2+ ) oscillations required for egg activation and embryo development in mammals. Supporting evidence for this role emerged from studies documenting its expression in all mammals and other vertebrate species, the physiological Ca2+ rises induced by injection of its messenger RNA into mammalian and nonmammalian eggs, and the lack of expression in infertile males that fail intracytoplasmic sperm injection. In the last year, genetic animal models have added support to its role as the long sought-after sperm factor. In this review, we highlight the findings that demonstrated the role of Ca2+ as the universal signal of egg activation and the experimental buildup that culminated with the identification of PLCζ as the soluble sperm factor. We also discuss the structural-functional properties that make PLCζ especially suited to evoke oscillations in eggs. Lastly, we examine unresolved aspects of the function and regulation of PLCζ and whether or not it is the only sperm factor in mammalian sperm.
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Affiliation(s)
- John Parrington
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Christophe Arnoult
- Université Grenoble Alpes, Grenoble, France.,Institut pour l'Avancée des Biosciences (IAB), INSERM 1209, CNRS UMR 5309, La Tronche, France
| | - Rafael A Fissore
- Department of Veterinary and Animal Sciences, University of Massachusetts, Amherst, Massachusetts
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19
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Anifandis G, Michopoulos A, Daponte A, Chatzimeletiou K, Simopoulou M, Messini CI, Polyzos NP, Vassiou K, Dafopoulos K, Goulis DG. Artificial oocyte activation: physiological, pathophysiological and ethical aspects. Syst Biol Reprod Med 2018; 65:3-11. [DOI: 10.1080/19396368.2018.1516000] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- George Anifandis
- Department of Obstetrics and Gynecology, ART Unit, University of Thessaly, School of Health Sciences, Faculty of Medicine, Larisa, Greece
| | - Alexandros Michopoulos
- Unit of Reproductive Endocrinology, 1st Department of Obstetrics and Gynecology, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Alexandros Daponte
- Department of Obstetrics and Gynecology, ART Unit, University of Thessaly, School of Health Sciences, Faculty of Medicine, Larisa, Greece
| | - Katerina Chatzimeletiou
- Unit of Human Reproduction, 1st Department of Obstetrics and Gynecology, Aristotle University Medical School, Papageorgiou General Hospital, Thessaloniki, Greece
| | - Mara Simopoulou
- Department of Physiology, Kapodistrian University of Athens, School of Health Sciences, Faculty of Medicine, Athens, Greece
| | - Christina I. Messini
- Department of Obstetrics and Gynecology, ART Unit, University of Thessaly, School of Health Sciences, Faculty of Medicine, Larisa, Greece
| | - Nikolas P. Polyzos
- Vrije Universiteit Brussel, Brussels, Belgium
- Universitair Ziekenhuis Brussel, Brussels, Belgium
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | - Katerina Vassiou
- Department of Anatomy, University of Thessaly, School of Health Sciences, Faculty of Medicine, Larisa, Greece
| | - Konstantinos Dafopoulos
- Department of Obstetrics and Gynecology, ART Unit, University of Thessaly, School of Health Sciences, Faculty of Medicine, Larisa, Greece
| | - Dimitrios G. Goulis
- Unit of Reproductive Endocrinology, 1st Department of Obstetrics and Gynecology, Aristotle University of Thessaloniki, Thessaloniki, Greece
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20
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Satouh Y, Ikawa M. New Insights into the Molecular Events of Mammalian Fertilization. Trends Biochem Sci 2018; 43:818-828. [PMID: 30170889 DOI: 10.1016/j.tibs.2018.08.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2018] [Revised: 07/30/2018] [Accepted: 08/04/2018] [Indexed: 12/20/2022]
Abstract
Currently, infertility affects ∼16% of couples worldwide. The causes are reported to involve both male and female factors, including fertilization failure between mature spermatozoa and eggs. However, the molecular mechanisms involved in each step of mammalian fertilization are yet to be fully elucidated. Although some of these steps can be rescued with assisted reproductive technologies, it is important to clarify the molecular mechanisms involved for the treatment and diagnosis of infertile couples. This review illustrates recent findings in mammalian fertilization, discovered by combining gene modification techniques with other new approaches, and aims to show how these findings will guide future research in mammalian fertilization.
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Affiliation(s)
- Yuhkoh Satouh
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 5650871, Japan.
| | - Masahito Ikawa
- Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 5650871, Japan; The Institute of Medical Science, The University of Tokyo, Tokyo 1088639, Japan.
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21
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Bueno V, Bastos H, Centeno L, Kretzmann N, Bertolini M, Mattos R, Rechsteiner SF. The Role of PLCζ and WPB2NL Gene Expression in Semen Quality and Fertility of Stallions. J Equine Vet Sci 2018. [DOI: 10.1016/j.jevs.2018.05.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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22
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Review: Sperm-oocyte interactions and their implications for bull fertility, with emphasis on the ubiquitin-proteasome system. Animal 2018; 12:s121-s132. [PMID: 29477154 DOI: 10.1017/s1751731118000253] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Fertilization is an intricate cascade of events that irreversibly alter the participating male and female gamete and ultimately lead to the union of paternal and maternal genomes in the zygote. Fertilization starts with sperm capacitation within the oviductal sperm reservoir, followed by gamete recognition, sperm-zona pellucida interactions and sperm-oolemma adhesion and fusion, followed by sperm incorporation, oocyte activation, pronuclear development and embryo cleavage. At fertilization, bull spermatozoon loses its acrosome and plasma membrane components and contributes chromosomes, centriole, perinuclear theca proteins and regulatory RNAs to the zygote. While also incorporated in oocyte cytoplasm, structures of the sperm tail, including mitochondrial sheath, axoneme, fibrous sheath and outer dense fibers are degraded and recycled. The ability of some of these sperm contributed components to give rise to functional zygotic structures and properly induce embryonic development may vary between bulls, bearing on their reproductive performance, and on the fitness, health, fertility and production traits of their offspring. Proper functioning, recycling and remodeling of gamete structures at fertilization is aided by the ubiquitin-proteasome system (UPS), the universal substrate-specific protein recycling pathway present in bovine and other mammalian oocytes and spermatozoa. This review is focused on the aspects of UPS relevant to bovine fertilization and bull fertility.
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23
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Sperm-borne phospholipase C zeta-1 ensures monospermic fertilization in mice. Sci Rep 2018; 8:1315. [PMID: 29358633 PMCID: PMC5778054 DOI: 10.1038/s41598-018-19497-6] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 01/03/2018] [Indexed: 12/23/2022] Open
Abstract
Sperm entry in mammalian oocytes triggers intracellular Ca2+ oscillations that initiate resumption of the meiotic cell cycle and subsequent activations. Here, we show that phospholipase C zeta 1 (PLCζ1) is the long-sought sperm-borne oocyte activation factor (SOAF). Plcz1 gene knockout (KO) mouse spermatozoa fail to induce Ca2+ changes in intracytoplasmic sperm injection (ICSI). In contrast to ICSI, Plcz1 KO spermatozoa induced atypical patterns of Ca2+ changes in normal fertilizations, and most of the fertilized oocytes ceased development at the 1–2-cell stage because of oocyte activation failure or polyspermy. We further discovered that both zona pellucida block to polyspermy (ZPBP) and plasma membrane block to polyspermy (PMBP) were delayed in oocytes fertilized with Plcz1 KO spermatozoa. With the observation that polyspermy is rare in astacin-like metalloendopeptidase (Astl) KO female oocytes that lack ZPBP, we conclude that PMPB plays more critical role than ZPBP in vivo. Finally, we obtained healthy pups from male mice carrying human infertile PLCZ1 mutation by single sperm ICSI supplemented with Plcz1 mRNA injection. These results suggest that mammalian spermatozoa have a primitive oocyte activation mechanism and that PLCζ1 is a SOAF that ensures oocyte activation steps for monospermic fertilization in mammals.
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24
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Freour T, Barragan M, Torra-Massana M, Ferrer-Vaquer A, Vassena R. Is there an association between PAWP/WBP2NL sequence, expression, and distribution in sperm cells and fertilization failures in ICSI cycles? Mol Reprod Dev 2018; 85:163-170. [PMID: 29271520 DOI: 10.1002/mrd.22950] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 12/11/2017] [Indexed: 02/01/2023]
Abstract
Successful fertilization in mammals depends on the sperm's ability to initiate intracellular Ca2+ oscillations in the egg, a phenomenon that is elicited by Sperm-oocyte activating factors (SOAFs), whose quantitative and/or qualitative defect might result in fertilization failure. One such proposed factor is Post-acrosomal WW domain-binding protein (PAWP/WBP2NL), although its ability to activate human oocytes has been questioned and its implication in human fertilization failure remains unknown. Here, we sought to determine if PAWP/WBP2NL expression and distribution in sperm cells associate with low/complete fertilization failure in males participating in intracytoplasmic sperm injection (ICSI) cycles. This prospective study was conducted on eight couples referred for elective ICSI with either the woman's own (n = 4) or a donor eggs (n = 4). Eight sperm donor samples used in ICSI, which resulted in normal fertilization rates, were used as the control group. For each male patient and donor sperm, PAWP/WBP2NL sequence, protein expression, and cellular distribution were analyzed by PCR amplification-sequencing, Western blot, and immunofluorescence, respectively. PAWP/WBP2NL was present in all samples, and no significant differences were detected between patients with fertilization failure and donors in sequence variants or mean protein expression, or in the proportion of PAWP/WBP2NL-positive sperm. In conclusion, no clear association between PAWP/WBP2NL protein expression in sperm and fertilization outcome in ICSI were observed from this cohort.
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Affiliation(s)
- Thomas Freour
- Clínica Eugin, Barcelona, Spain.,Service de médecine de la reproduction, CHU de Nantes, Nantes, France.,Inserm UMR1064-ITUN, Nantes, France.,Faculté de médecine, Université de Nantes, Nantes, France
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25
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Abbasi F, Miyata H, Ikawa M. Revolutionizing male fertility factor research in mice by using the genome editing tool CRISPR/Cas9. Reprod Med Biol 2018; 17:3-10. [PMID: 29371815 PMCID: PMC5768971 DOI: 10.1002/rmb2.12067] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 09/01/2014] [Indexed: 12/21/2022] Open
Abstract
Background Reproductive research is quintessential in understanding not only the cause of infertility, but also for creating family planning tools. The knockout (KO) system approach is conducive to discovering genes that are essential for fertility in mice. However, in vivo research has been limited due to its high cost and length of time needed to establish KO mice. Methods The mechanisms behind the CRISPR/Cas9 system and its application in investigating male fertility in mice are described by using original and review articles. Results The CRISPR/CAS9 SYSTEM has enabled researchers to rapidly, efficiently, and inexpensively produce genetically modified mice to study male fertility. Several genes have been highlighted that were found to be indispensable for male fertility by using the CRISPR/Cas9 system, as well as more complicated gene manipulation techniques, such as point mutations, tag insertions, and double knockouts, which have become easier with this new technology. Conclusion In order to increase efficiency and usage, new methods of CRISPR/Cas9 integration are being developed, such as electroporation and applying the system to embryonic stem cells. The hidden mysteries of male fertility will be unraveled with the help of this new technology.
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Affiliation(s)
- Ferheen Abbasi
- Research Institute for Microbial DiseasesOsaka UniversitySuitaJapan
- Graduate School of MedicineOsaka UniversitySuitaJapan
| | - Haruhiko Miyata
- Research Institute for Microbial DiseasesOsaka UniversitySuitaJapan
| | - Masahito Ikawa
- Research Institute for Microbial DiseasesOsaka UniversitySuitaJapan
- Graduate School of MedicineOsaka UniversitySuitaJapan
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26
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Universality and Diversity of a Fast, Electrical Block to Polyspermy During Fertilization in Animals. DIVERSITY AND COMMONALITY IN ANIMALS 2018. [DOI: 10.1007/978-4-431-56609-0_24] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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27
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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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28
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Xu YR, Yang WX. Calcium influx and sperm-evoked calcium responses during oocyte maturation and egg activation. Oncotarget 2017; 8:89375-89390. [PMID: 29179526 PMCID: PMC5687696 DOI: 10.18632/oncotarget.19679] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 06/19/2017] [Indexed: 12/18/2022] Open
Abstract
Under the guidance and regulation of hormone signaling, large majority of mammalian oocytes go through twice cell cycle arrest-resumption prior to the fertilized egg splits: oocyte maturation and egg activation. Cytosolic free calcium elevations and endoplasmic reticulum calcium store alternations are actively involved in triggering the complex machineries and events during oogenesis. Among these, calcium influx had been implicated in the replenishment of endoplasmic reticulum store during oocyte maturation and calcium oscillation during egg activation. This process also drove successful fertilization and early embryo development. Store-operated Ca2+ entry, acts as the principal force of calcium influx, is composed of STIM1 and Orai1 on the plasma membrane. Besides, transient receptor potential channels also participate in the process of calcium inwards. In this review, we summarize the recent researches on the spatial-temporal distribution of store-operated calcium entry components and transient receptor potential channels. Questions about how these channels play function for calcium influx and what impacts these channels have on oocytes are discussed. At the time of sperm-egg fusion, sperm-specific factor(s) diffuse and enable eggs to mount intracellular calcium oscillations. In this review, we also focus on the basic knowledge and the modes of action of the potential sperm factor phospholipase C zeta, as well as the downstream receptor, type 1 inositol 1,4,5-trisphosphate receptor. From the achievement in the previous several decades, it is easy to find that there are too many doubtful points in the field that need researchers take into consideration and take action in the future.
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Affiliation(s)
- Ya-Ru Xu
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou, China
| | - Wan-Xi Yang
- The Sperm Laboratory, College of Life Sciences, Zhejiang University, Hangzhou, China
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29
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Hachem A, Godwin J, Ruas M, Lee HC, Ferrer Buitrago M, Ardestani G, Bassett A, Fox S, Navarrete F, de Sutter P, Heindryckx B, Fissore R, Parrington J. PLCζ is the physiological trigger of the Ca 2+ oscillations that induce embryogenesis in mammals but conception can occur in its absence. Development 2017; 144:2914-2924. [PMID: 28694258 DOI: 10.1242/dev.150227] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2017] [Accepted: 07/01/2017] [Indexed: 12/21/2022]
Abstract
Activation of the egg by the sperm is the first, vital stage of embryogenesis. The sperm protein PLCζ has been proposed as the physiological agent that triggers the Ca2+ oscillations that normally initiate embryogenesis. Consistent with this, recombinant PLCζ induces Ca2+ oscillations in eggs and debilitating mutations in the PLCZ1 gene are associated with infertility in men. However, there has been no evidence that knockout of the gene encoding PLCζ abolishes the ability of sperm to induce Ca2+ oscillations in eggs. Here, we show that sperm derived from Plcz1-/- male mice fail to trigger Ca2+ oscillations in eggs, cause polyspermy and thus demonstrate that PLCζ is the physiological trigger of these Ca2+ oscillations. Remarkably, some eggs fertilized by PLCζ-null sperm can develop, albeit at greatly reduced efficiency, and after a significant time-delay. In addition, Plcz1-/- males are subfertile but not sterile, suggesting that in the absence of PLCζ, spontaneous egg activation can eventually occur via an alternative route. This is the first demonstration that in vivo fertilization without the normal physiological trigger of egg activation can result in offspring. PLCζ-null sperm now make it possible to resolve long-standing questions in fertilization biology, and to test the efficacy and safety of procedures used to treat human infertility.
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Affiliation(s)
- Alaa Hachem
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Jonathan Godwin
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Margarida Ruas
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Hoi Chang Lee
- Department of Veterinary and Animal Sciences, University of Massachusetts, 661 North Pleasant Street, Amherst, MA 01003-9286, USA
| | - Minerva Ferrer Buitrago
- Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Goli Ardestani
- Department of Veterinary and Animal Sciences, University of Massachusetts, 661 North Pleasant Street, Amherst, MA 01003-9286, USA
| | - Andrew Bassett
- Sir William Dunn School of Pathology, University of Oxford, South Parks Road, Oxford OX1 3RE, UK
| | - Sebastian Fox
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - Felipe Navarrete
- Department of Veterinary and Animal Sciences, University of Massachusetts, 661 North Pleasant Street, Amherst, MA 01003-9286, USA
| | - Petra de Sutter
- Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Björn Heindryckx
- Department for Reproductive Medicine, Ghent University Hospital, De Pintelaan 185, 9000 Ghent, Belgium
| | - Rafael Fissore
- Department of Veterinary and Animal Sciences, University of Massachusetts, 661 North Pleasant Street, Amherst, MA 01003-9286, USA
| | - John Parrington
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
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Tavalaee M, Kiani-Esfahani A, Nasr-Esfahani MH. Relationship between phospholipase C-zeta, semen parameters, and chromatin status. Syst Biol Reprod Med 2017; 63:259-268. [PMID: 28345968 DOI: 10.1080/19396368.2017.1298006] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The need for additional tests to complement basic sperm analysis in clinics is well appreciated. In this regard, a number of tests such as sperm DNA integrity test as a tool in diagnosis and treatment of infertility are suggested. But recent studies have focused on main sperm factors involved in oocyte activation such as phospholipase C-zeta (PLCζ) that initiate intracellular Ca2+ signaling and embryogenesis. Therefore, this study aimed to investigate the relationship between PLCζ, basic semen parameters, sperm DNA fragmentation (SDF), and protamine deficiency in men with normal (n=32) and abnormal (n=23) semen parameters. Unlike SDF and protamine deficiency, as negative factors related to fertility, the mean value of PLCζ as positive factor related to infertility was significantly lower in men with abnormal semen parameters compared to men with normal semen parameters. Significant correlations were also observed between sperm concentration, motility, and abnormal morphology with the percentage of PLCζ positive spermatozoa. In addition, logistic regression analysis revealed that sperm morphology is more predictive than sperm motility and concentration for PLCζ presence. In addition, a statistically significant negative relationship was observed between the percentage of PLCζ positive spermatozoa and SDF. These findings suggested during ICSI, selection of sperm based on morphology has a profound effect on its ability to induce oocyte activation based on the likelihood of PLCζ expression. Therefore, assessment of PLCζ as an index for fertilization potential of a semen sample in men with severe teratozoospermia may define individuals who are candidates for artificial oocyte activation (AOA) and may avoid failed fertilization post ICSI.
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Affiliation(s)
- Marziyeh Tavalaee
- a Department of Reproductive Biotechnology , Reproductive Biomedicine Research Center, Royan Institute for Biotechnology , ACECR , Isfahan , Iran
| | - Abbas Kiani-Esfahani
- a Department of Reproductive Biotechnology , Reproductive Biomedicine Research Center, Royan Institute for Biotechnology , ACECR , Isfahan , Iran
| | - Mohammad H Nasr-Esfahani
- a Department of Reproductive Biotechnology , Reproductive Biomedicine Research Center, Royan Institute for Biotechnology , ACECR , Isfahan , Iran.,b Isfahan Fertility and Infertility Center , Isfahan , Iran
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31
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Freour T, Barragan M, Ferrer-Vaquer A, Rodríguez A, Vassena R. WBP2NL/PAWP mRNA and protein expression in sperm cells are not related to semen parameters, fertilization rate, or reproductive outcome. J Assist Reprod Genet 2017; 34:803-810. [PMID: 28444612 DOI: 10.1007/s10815-017-0902-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 03/05/2017] [Indexed: 02/04/2023] Open
Abstract
PURPOSE WBP2NL/PAWP, a protein found in the post-acrosomal region of mammalian spermatozoa, has been proposed as a sperm-borne oocyte-activating factor (SOAF) contributing to Ca2+ release within the oocyte and subsequent fertilization and embryo development. However, its relevance as either a diagnostic or a prognostic marker of fertilization failure has been questioned in the recent literature. We analyzed WBP2NL/PAWP gene and protein expression level and localization in patients without previous intracytoplasmic sperm injection (ICSI) cycles in order to assess its association with both sperm characteristics and ability to fertilize. METHODS Raw frozen-thawed semen samples from 33 couples referred for oocyte donation were included in the study during 2015. Relative protein expression versus α-tubulin (western blot, WB), proportion of post-acrosomal WBP2NL/PAWP-positive spermatozoa over the total number of sperm cells (immunofluorescence), and WBP2NL/PAWP gene expression (RT-qPCR) were analyzed and correlated with semen analysis parameters (number, motility, and morphology) and with reproductive outcomes. RESULTS WBP2NL/PAWP protein was expressed in all samples with high variability: relative protein expression (1.77 ± 0.8, range [0.4-3.7]), proportion of positive cells (49.6% ± 16.1, range [22-89]), and relative gene expression (7.3 ± 8.2). No significant correlation (R 2 < 0.1) was found between gene and protein expression, neither between WBP2NL/PAWP gene or protein expression, and fertilization rate or other reproductive outcomes (i.e., pregnancy). In contrast, we found significant correlation between sperm morphology and WBP2NL/PAWP semiquantitative analysis in WB (r = -0.42, p < 0.05) and for sperm motility and WBP2NL/PAWP expression in IF (r = 0.52, p < 0.05). CONCLUSION Taken into account that WBP2NL/PAWP gene and protein levels and distribution did not correlate with fertilization rates, this study questions the interest of WBP2NL/PAWP protein and gene expression analysis in sperm cells as a prognostic factor for the outcome of ICSI cycles. Larger studies focusing on WBP2NL/PAWP protein and gene expression are needed in order to evaluate the role of WBP2NL/PAWP as a prognostic factor for ART.
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Affiliation(s)
- T Freour
- Clínica Eugin, Traversera de les Corts, 322 - 08029, Barcelona, Spain.,Service de médecine de la reproduction, CHU de Nantes, 44093, Nantes, France.,Inserm UMR1064 - ITUN, 44000, Nantes, France.,Faculté de médecine, Université de Nantes, 44000, Nantes, France
| | - M Barragan
- Clínica Eugin, Traversera de les Corts, 322 - 08029, Barcelona, Spain
| | - A Ferrer-Vaquer
- Clínica Eugin, Traversera de les Corts, 322 - 08029, Barcelona, Spain
| | - A Rodríguez
- Clínica Eugin, Traversera de les Corts, 322 - 08029, Barcelona, Spain
| | - Rita Vassena
- Clínica Eugin, Traversera de les Corts, 322 - 08029, Barcelona, Spain.
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32
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Male infertility-linked point mutation reveals a vital binding role for the C2 domain of sperm PLCζ. Biochem J 2017; 474:1003-1016. [PMID: 28270562 DOI: 10.1042/bcj20161057] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2016] [Revised: 01/05/2017] [Accepted: 01/20/2017] [Indexed: 12/14/2022]
Abstract
Sperm-specific phospholipase C zeta (PLCζ) is widely considered to be the physiological stimulus that evokes intracellular calcium (Ca2+) oscillations that are essential for the initiation of egg activation during mammalian fertilisation. A recent genetic study reported a male infertility case that was directly associated with a point mutation in the PLCζ C2 domain, where an isoleucine residue had been substituted with a phenylalanine (I489F). Here, we have analysed the effect of this mutation on the in vivo Ca2+ oscillation-inducing activity and the in vitro biochemical properties of human PLCζ. Microinjection of cRNA or recombinant protein corresponding to PLCζI489F mutant at physiological concentrations completely failed to cause Ca2+ oscillations and trigger development. However, this infertile phenotype could be effectively rescued by microinjection of relatively high (non-physiological) amounts of recombinant mutant PLCζI489F protein, leading to Ca2+ oscillations and egg activation. Our in vitro biochemical analysis suggested that the PLCζI489F mutant displayed similar enzymatic properties, but dramatically reduced binding to PI(3)P and PI(5)P-containing liposomes compared with wild-type PLCζ. Our findings highlight the importance of PLCζ at fertilisation and the vital role of the C2 domain in PLCζ function, possibly due to its novel binding characteristics.
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33
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Martin JH, Bromfield EG, Aitken RJ, Nixon B. Biochemical alterations in the oocyte in support of early embryonic development. Cell Mol Life Sci 2017; 74:469-485. [PMID: 27604868 PMCID: PMC11107538 DOI: 10.1007/s00018-016-2356-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 08/28/2016] [Accepted: 09/01/2016] [Indexed: 01/01/2023]
Abstract
Notwithstanding the enormous reproductive potential encapsulated within a mature mammalian oocyte, these cells present only a limited window for fertilization before defaulting to an apoptotic cascade known as post-ovulatory oocyte aging. The only cell with the capacity to rescue this potential is the fertilizing spermatozoon. Indeed, the union of these cells sets in train a remarkable series of events that endows the oocyte with the capacity to divide and differentiate into the trillions of cells that comprise a new individual. Traditional paradigms hold that, beyond the initial stimulation of fluctuating calcium (Ca2+) required for oocyte activation, the fertilizing spermatozoon plays limited additional roles in the early embryo. While this model has now been drawn into question in view of the recent discovery that spermatozoa deliver developmentally important classes of small noncoding RNAs and other epigenetic modulators to oocytes during fertilization, it is nevertheless apparent that the primary responsibility for oocyte activation rests with a modest store of maternally derived proteins and mRNA accumulated during oogenesis. It is, therefore, not surprising that widespread post-translational modifications, in particular phosphorylation, hold a central role in endowing these proteins with sufficient functional diversity to initiate embryonic development. Indeed, proteins targeted for such modifications have been linked to oocyte activation, recruitment of maternal mRNAs, DNA repair and resumption of the cell cycle. This review, therefore, seeks to explore the intimate relationship between Ca2+ release and the suite of molecular modifications that sweep through the oocyte to ensure the successful union of the parental germlines and ensure embryogenic fidelity.
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Affiliation(s)
- Jacinta H Martin
- Discipline of Biological Sciences and Priority Research Center for Reproductive Science, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia.
| | - Elizabeth G Bromfield
- Discipline of Biological Sciences and Priority Research Center for Reproductive Science, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia
| | - R John Aitken
- Discipline of Biological Sciences and Priority Research Center for Reproductive Science, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia
| | - Brett Nixon
- Discipline of Biological Sciences and Priority Research Center for Reproductive Science, School of Environmental and Life Sciences, The University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia
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34
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Yeste M, Jones C, Amdani SN, Coward K. Oocyte Activation and Fertilisation: Crucial Contributors from the Sperm and Oocyte. Results Probl Cell Differ 2017; 59:213-239. [PMID: 28247051 DOI: 10.1007/978-3-319-44820-6_8] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
This chapter intends to summarise the importance of sperm- and oocyte-derived factors in the processes of sperm-oocyte binding and oocyte activation. First, we describe the initial interaction between sperm and the zona pellucida, with particular regard to acrosome exocytosis. We then describe how sperm and oocyte membranes fuse, with special reference to the discovery of the sperm protein IZUMO1 and its interaction with the oocyte membrane receptor JUNO. We then focus specifically upon oocyte activation, the fundamental process by which the oocyte is alleviated from metaphase II arrest by a sperm-soluble factor. The identity of this sperm factor has been the source of much debate recently, although mounting evidence, from several different laboratories, provides strong support for phospholipase C ζ (PLCζ), a sperm-specific phospholipase. Herein, we discuss the evidence in support of PLCζ and evaluate the potential role of other candidate proteins, such as post-acrosomal WW-binding domain protein (PAWP/WBP2NL). Since the cascade of downstream events triggered by the sperm-borne oocyte activation factor heavily relies upon specialised cellular machinery within the oocyte, we also discuss the critical role of oocyte-borne factors, such as the inositol trisphosphate receptor (IP3R), protein kinase C (PKC), store-operated calcium entry (SOCE) and calcium/calmodulin-dependent protein kinase II (CaMKII), during the process of oocyte activation. In order to place the implications of these various factors and processes into a clinical context, we proceed to describe their potential association with oocyte activation failure and discuss how clinical techniques such as the in vitro maturation of oocytes may affect oocyte activation ability. Finally, we contemplate the role of artificial oocyte activating agents in the clinical rescue of oocyte activation deficiency and discuss options for more endogenous alternatives.
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Affiliation(s)
- Marc Yeste
- Unit of Cell Biology, Department of Biology, Faculty of Sciences, University of Girona, C/ Maria Aurèlia Campany, 69, Campus Montilivi, E-17071, Girona, Spain. .,Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Headington, Oxford, UK.
| | - Celine Jones
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Headington, Oxford, UK
| | - Siti Nornadhirah Amdani
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Headington, Oxford, UK
| | - Kevin Coward
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, Level 3, Women's Centre, John Radcliffe Hospital, Headington, Oxford, UK
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36
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Kashir J, Buntwal L, Nomikos M, Calver BL, Stamatiadis P, Ashley P, Vassilakopoulou V, Sanders D, Knaggs P, Livaniou E, Bunkheila A, Swann K, Lai FA. Antigen unmasking enhances visualization efficacy of the oocyte activation factor, phospholipase C zeta, in mammalian sperm. Mol Hum Reprod 2016; 23:54-67. [PMID: 27932551 DOI: 10.1093/molehr/gaw073] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/23/2016] [Accepted: 11/21/2016] [Indexed: 12/14/2022] Open
Abstract
STUDY QUESTION Is it possible to improve clinical visualization of phospholipase C zeta (PLCζ) as a diagnostic marker of sperm oocyte activation capacity and male fertility? SUMMARY ANSWER Poor PLCζ visualization efficacy using current protocols may be due to steric or conformational occlusion of native PLCζ, hindering antibody access, and is significantly enhanced using antigen unmasking/retrieval (AUM) protocols. WHAT IS KNOWN ALREADY Mammalian oocyte activation is mediated via a series of intracellular calcium (Ca2+) oscillations induced by sperm-specific PLCζ. PLCζ represents not only a potential clinical therapeutic in cases of oocyte activation deficiency but also a diagnostic marker of sperm fertility. However, there are significant concerns surrounding PLCζ antibody specificity and detection protocols. STUDY DESIGN, SIZE DURATION Two PLCζ polyclonal antibodies, with confirmed PLCζ specificity, were employed in mouse, porcine and human sperm. Experiments evaluated PLCζ visualization efficacy, and whether AUM improved this. Antibodies against two sperm-specific proteins [post-acrosomal WW-binding protein (PAWP) and acrosin] were used as controls. PARTICIPANTS/MATERIALS, SETTING, METHODS Aldehyde- and methanol-fixed sperm were subject to immunofluorescence analysis following HCl exposure (pH = 0.1-0.5), acid Tyrode's solution exposure (pH = 2.5) or heating in 10 mM sodium citrate solution (pH = 6.0). Fluorescence intensity of at least 300 cells was recorded for each treatment, with three independent repeats. MAIN RESULTS AND THE ROLE OF CHANCE Despite high specificity for native PLCζ following immunoblotting using epitope-specific polyclonal PLCζ antibodies in mouse, porcine and human sperm, immunofluorescent visualization efficacy was poor. In contrast, sperm markers PAWP and acrosin exhibited relatively impressive results. All methods of AUM on aldehyde-fixed sperm enhanced visualization efficacy for PLCζ compared to visualization efficacy before AUM (P < 0.05 for all AUM interventions), but exerted no significant change upon PAWP or acrosin immunofluorescence following AUM. All methods of AUM enhanced PLCζ visualization efficacy in mouse and human methanol-fixed sperm compared to without AUM (P < 0.05 for all AUM interventions), while no significant change was observed in methanol-fixed porcine sperm before and after. In the absence of aldehyde-induced cross-linkages, such results suggest that poor PLCζ visualization efficacy may be due to steric or conformational occlusion of native PLCζ, hindering antibody access. Importantly, examination of sperm from individual donors revealed that AUM differentially affects observable PLCζ fluorescence, and the proportion of sperm exhibiting detectable PLCζ fluorescence in sperm from different males. LIMITATIONS, REASONS FOR CAUTION Direct correlation of fertility outcomes with the level of PLCζ in the sperm samples studied was not available. Such analyses would be required in future to determine whether the improved methodology for PLCζ visualization we propose would indeed reflect fertility status. WIDER IMPLICATIONS OF THE FINDINGS We propose that AUM alters conformational interactions to enhance PLCζ epitope availability and visualization efficacy, supporting prospective application of AUM to reduce misinterpretation in clinical diagnosis of PLCζ-linked male infertility. Our current results suggest that it is perhaps prudent that previous studies investigating links between PLCζ and fertility parameters are re-examined in the context of AUM, and may pave the way for future work to answer significant questions such as how PLCζ appears to be kept in an inactive form in the sperm. LARGE SCALE DATA Not applicable. STUDY FUNDING/COMPETING INTERESTS J.K. is supported by a Health Fellowship award from the National Institute for Social Care and Health Research (NISCHR). M.N. is supported by a Marie Curie Intra-European Research Fellowship award. This work was also partly funded by a research grant from Cook Medical Technologies LLC. There are no competing financial interests to declare.
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Affiliation(s)
- Junaid Kashir
- College of Biomedical and Life Sciences, Schools of Bioscience & Medicine, 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
| | - Luke Buntwal
- College of Biomedical and Life Sciences, Schools of Bioscience & Medicine, Cardiff University, Cardiff, UK
| | - Michail Nomikos
- Qatar University, College of Medicine, PO BOX 2713, Doha, Qatar.,School of Medicine, Cardiff University, UK
| | - Brian L Calver
- College of Biomedical and Life Sciences, Schools of Bioscience & Medicine, Cardiff University, Cardiff, UK
| | - Panagiotis Stamatiadis
- College of Biomedical and Life Sciences, Schools of Bioscience & Medicine, Cardiff University, Cardiff, UK
| | - Peter Ashley
- Wales Fertility Institute, University Hospital Wales, Cardiff, UK
| | | | - David Sanders
- Wales Fertility Institute, University Hospital Wales, Cardiff, UK
| | - Paul Knaggs
- Wales Fertility Institute, University Hospital Wales, Cardiff, UK
| | - Evangelia Livaniou
- National Center for Scientific Research 'Demokritos', 15310 Aghia Paraskevi, Greece
| | - Adnan Bunkheila
- Wales Fertility Institute, University Hospital Wales, Cardiff, UK
| | - Karl Swann
- College of Biomedical and Life Sciences, Schools of Bioscience & Medicine, Cardiff University, Cardiff, UK
| | - F Anthony Lai
- College of Biomedical and Life Sciences, Schools of Bioscience & Medicine, Cardiff University, Cardiff, UK
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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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Janghorban-Laricheh E, Ghazavi-Khorasgani N, Tavalaee M, Zohrabi D, Abbasi H, Nasr-Esfahani MH. An association between sperm PLCζ levels and varicocele? J Assist Reprod Genet 2016; 33:1649-1655. [PMID: 27612872 DOI: 10.1007/s10815-016-0802-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 08/19/2016] [Indexed: 10/21/2022] Open
Abstract
PURPOSE We aimed to compare the expression of phospholipase C ζ (PLCζ), as one of the main sperm factors involved in oocyte activation, at both RNA and protein levels in fertile men and those with varicocele. METHODS This study included 35 individuals with male factor infertility presenting primary infertility with grade II and III unilateral varicocele and 20 fertile men without varicocele. Semen parameters were assessed according to WHO 2010. Sperm DNA fragmentation, relative expression of PLCζ at messenger RNA, and protein levels were evaluated by sperm chromatin structure assay (SCSA), real-time PCR, and Western blot analysis, respectively. RESULTS The results of this study reveal that the mean relative expression of PLCζ was significantly lower in individuals with varicocele compared to fertile men at both transcription and translation levels. In addition, the percentage of DNA fragmentation was significantly higher in infertile men with varicocele compared to fertile men. CONCLUSIONS The findings of the present study illustrate that one of the etiologies of reduced fertility associated with varicocele is the low expression of PLCζ. This effect could subsequently reduce the sperm ability to induce oocyte activation. Therefore, these results hold promise to modify our understanding of reproductive physiology of varicocele state.
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Affiliation(s)
- Elham Janghorban-Laricheh
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran.,Department of Biology, Nourdanesh Institute of Higher Education, Meymeh, Isfahan, Iran
| | - Nasim Ghazavi-Khorasgani
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran.,Department of Biology, Nourdanesh Institute of Higher Education, Meymeh, Isfahan, Iran
| | - Marziyeh Tavalaee
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Dina Zohrabi
- Department of Biology, Nourdanesh Institute of Higher Education, Meymeh, Isfahan, Iran
| | | | - Mohammad H Nasr-Esfahani
- Department of Reproductive Biotechnology, Reproductive Biomedicine Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran. .,Isfahan Fertility and Infertility Center, Isfahan, Iran.
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Structural and functional insights into IZUMO1 recognition by JUNO in mammalian fertilization. Nat Commun 2016; 7:12198. [PMID: 27416963 PMCID: PMC4947182 DOI: 10.1038/ncomms12198] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2016] [Accepted: 06/10/2016] [Indexed: 01/04/2023] Open
Abstract
Sperm–egg fusion is the critical step in mammalian fertilization, and requires the interaction between IZUMO1 on the sperm surface and JUNO (also known as folate receptor (FR) 4 or IZUMO1R) on the egg surface. Whereas other FRs bind and uptake folates, JUNO binds IZUMO1 and establishes the cell–cell adhesion. However, the mechanism of IZUMO1 recognition by JUNO has remained elusive. Here we report the crystal structure of mouse JUNO, at 2.3 Å resolution. A structural comparison of JUNO with the FRs revealed that JUNO and the FRs have similar overall structures, but JUNO lacks the folate-binding pocket, thereby explaining the inability of JUNO to bind folate. Further complementation of Juno knockout eggs with mutant Juno messenger RNAs revealed that the conserved, surface-exposed tryptophan residue of JUNO is required for sperm binding and fertilization. Our structure-based in vivo functional analyses provide a framework towards a mechanistic understanding of mammalian gamete recognition. Sperm-egg fusion requires the interaction between IZUMO1 on the sperm and JUNO on the egg. Here, the authors report the crystal structure of mouse JUNO, and use it to explain its lack of binding to folate, along with in vivo functional analyses.
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40
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Tosti E, Ménézo Y. Gamete activation: basic knowledge and clinical applications. Hum Reprod Update 2016; 22:420-39. [PMID: 27278231 PMCID: PMC4917743 DOI: 10.1093/humupd/dmw014] [Citation(s) in RCA: 67] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 04/01/2016] [Indexed: 01/07/2023] Open
Abstract
Background The first clues to the process of gamete activation date back to nearly 60 years ago. The mutual activation of gametes is a crucial event during fertilization. In the testis and ovaries, spermatozoa and oocytes are in a state of meiotic and metabolic quiescence and require reciprocal signals in order to undergo functional changes that lead to competence for fertilization. First, the oocyte activates sperm by triggering motility, chemoattraction, binding and the acrosome reaction, culminating with the fusion of the two plasma membranes. At the end of this cascade of events, collectively known as sperm capacitation, sperm-induced oocyte activation occurs, generating electrical, morphological and metabolic modifications in the oocyte. Objective and rationale The aim of this review is to provide the current state of knowledge regarding the entire process of gamete activation in selected specific animal models that have contributed to our understanding of fertilization in mammals, including humans. Here we describe in detail the reciprocal induction of the two activation processes, the molecules involved and the mechanisms of cell interaction and signal transduction that ultimately result in successful embryo development and creation of a new individual. Search methods We carried out a literature survey with no restrictions on publication date (from the early 1950s to March 2016) using PubMed/Medline, Google Scholar and Web of Knowledge by utilizing common keywords applied in the field of fertilization and embryo development. We also screened the complete list of references published in the most recent research articles and relevant reviews published in English (both animal and human studies) on the topics investigated. Outcomes Literature on the principal animal models demonstrates that gamete activation is a pre-requisite for successful fertilization, and is a process common to all species studied to date. We provide a detailed description of the dramatic changes in gamete morphology and behavior, the regulatory molecules triggering gamete activation and the intracellular ions and second messengers involved in active metabolic pathways in different species. Recent scientific advances suggest that artificial gamete activation may represent a novel technique to improve human IVF outcomes, but this approach requires caution. Wider implications Although controversial, manipulation of gamete activation represents a promising tool for ameliorating the fertilization rate in assisted reproductive technologies. A better knowledge of mechanisms that transform the quiescent oocyte into a pluripotent cell may also provide new insights for the clinical use of stem cells.
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Affiliation(s)
- Elisabetta Tosti
- Stazione Zoologica Anton Dohrn, Villa Comunale, Naples 80121, Italy
| | - Yves Ménézo
- London Fertility Associates, 104 Harley Street, London WIG7JD, UK
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Sanders JR, Swann K. Molecular triggers of egg activation at fertilization in mammals. Reproduction 2016; 152:R41-50. [PMID: 27165049 DOI: 10.1530/rep-16-0123] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2016] [Accepted: 05/09/2016] [Indexed: 01/15/2023]
Abstract
In mammals, the sperm activates the development of the egg by triggering a series of oscillations in the cytosolic-free Ca(2+) concentration (Ca(2+) i). The sperm triggers these cytosolic Ca(2+i) oscillations after sperm-egg membrane fusion, as well as after intracytoplasmic sperm injection (ICSI). These Ca(2+) i oscillations are triggered by a protein located inside the sperm. The identity of the sperm protein has been debated over many years, but all the repeatable data now suggest that it is phospholipase Czeta (PLCζ). The main downstream target of Ca(2+) i oscillations is calmodulin-dependent protein kinase II (CAMKII (CAMK2A)), which phosphorylates EMI2 and WEE1B to inactivate the M-phase promoting factor protein kinase activity (MPF) and this ultimately triggers meiotic resumption. A later decline in the activity of mitogen-activated protein kinase (MAPK) then leads to the completion of activation which is marked by the formation of pronuclei and entry into interphase of the first cell cycle. The early cytosolic Ca(2+) increases also trigger exocytosis via a mechanism that does not involve CAMKII. We discuss some recent developments in our understanding of these triggers for egg activation within the framework of cytosolic Ca(2+) signaling.
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Affiliation(s)
| | - Karl Swann
- School of BiosciencesCardiff University, Cardiff, UK
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Escoffier J, Lee HC, Yassine S, Zouari R, Martinez G, Karaouzène T, Coutton C, Kherraf ZE, Halouani L, Triki C, Nef S, Thierry-Mieg N, Savinov SN, Fissore R, Ray PF, Arnoult C. Homozygous mutation of PLCZ1 leads to defective human oocyte activation and infertility that is not rescued by the WW-binding protein PAWP. Hum Mol Genet 2016; 25:878-91. [PMID: 26721930 PMCID: PMC4754041 DOI: 10.1093/hmg/ddv617] [Citation(s) in RCA: 96] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 12/06/2015] [Accepted: 12/17/2015] [Indexed: 11/13/2022] Open
Abstract
In mammals, sperm-oocyte fusion initiates Ca(2+) oscillations leading to a series of events called oocyte activation, which is the first stage of embryo development. Ca(2+) signaling is elicited by the delivery of an oocyte-activating factor by the sperm. A sperm-specific phospholipase C (PLCZ1) has emerged as the likely candidate to induce oocyte activation. Recently, PAWP, a sperm-born tryptophan domain-binding protein coded by WBP2NL, was proposed to serve the same purpose. Here, we studied two infertile brothers exhibiting normal sperm morphology but complete fertilization failure after intracytoplasmic sperm injection. Whole exomic sequencing evidenced a missense homozygous mutation in PLCZ1, c.1465A>T; p.Ile489Phe, converting Ile 489 into Phe. We showed the mutation is deleterious, leading to the absence of the protein in sperm, mislocalization of the protein when injected in mouse GV and MII oocytes, highly abnormal Ca(2+) transients and early embryonic arrest. Altogether these alterations are consistent with our patients' sperm inability to induce oocyte activation and initiate embryo development. In contrast, no deleterious variants were identified in WBP2NL and PAWP presented normal expression and localization. Overall we demonstrate in humans, the absence of PLCZ1 alone is sufficient to prevent oocyte activation irrespective of the presence of PAWP. Additionally, it is the first mutation located in the C2 domain of PLCZ1, a domain involved in targeting proteins to cell membranes. This opens the door to structure-function studies to identify the conserved amino acids of the C2 domain that regulate the targeting of PLCZ1 and its selectivity for its lipid substrate(s).
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Affiliation(s)
- Jessica Escoffier
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | | | - Sandra Yassine
- Université Grenoble Alpes, Grenoble, F-38000, Grenoble, France, Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Raoudha Zouari
- Polyclinique les Jasmins, Centre d'Aide Médicale à la Procréation, Centre Urbain Nord, 1003 Tunis, Tunisia
| | - Guillaume Martinez
- Université Grenoble Alpes, Grenoble, F-38000, Grenoble, France, Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Thomas Karaouzène
- Université Grenoble Alpes, Grenoble, F-38000, Grenoble, France, Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Charles Coutton
- Université Grenoble Alpes, Grenoble, F-38000, Grenoble, France, CHU de Grenoble, UF de Génétique Chromosomique, Grenoble F-38000, France
| | - Zine-Eddine Kherraf
- Université Grenoble Alpes, Grenoble, F-38000, Grenoble, France, Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France
| | - Lazhar Halouani
- Polyclinique les Jasmins, Centre d'Aide Médicale à la Procréation, Centre Urbain Nord, 1003 Tunis, Tunisia
| | - Chema Triki
- Clinique Hannibal, Centre d'AMP, les berges du lac, 1053 Tunis, Tunisia
| | - Serge Nef
- Department of Genetic Medicine and Development, University of Geneva Medical School, Geneva, Switzerland
| | - Nicolas Thierry-Mieg
- Université Grenoble Alpes, Grenoble, F-38000, Grenoble, France, Laboratoire TIMC-IMAG, UMR CNRS 5525, Grenoble F-38000, France and
| | - Sergey N Savinov
- Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, MA 01003, USA
| | | | - Pierre F Ray
- Université Grenoble Alpes, Grenoble, F-38000, Grenoble, France, Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France, CHU de Grenoble, UF de Biochimie et Génétique Moléculaire, Grenoble F-38000, France
| | - Christophe Arnoult
- Université Grenoble Alpes, Grenoble, F-38000, Grenoble, France, Institut Albert Bonniot, INSERM U823, La Tronche F-38700, France,
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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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