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Cao H, Li L, Liu S, Wang Y, Liu X, Yang F, Dong W. The multifaceted role of extracellular ATP in sperm function: From spermatogenesis to fertilization. Theriogenology 2024; 214:98-106. [PMID: 37865020 DOI: 10.1016/j.theriogenology.2023.10.019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 10/09/2023] [Accepted: 10/15/2023] [Indexed: 10/23/2023]
Abstract
Extracellular adenosine 5'-triphosphate (ATP) is a vital signaling molecule involved in various physiological processes within the body. In recent years, studies have revealed its significant role in male reproduction, particularly in sperm function. This review explores the multifaceted role of extracellular ATP in sperm function, from spermatogenesis to fertilization. We discuss the impact of extracellular ATP on spermatogenesis, sperm maturation and sperm-egg fusion, highlighting the complex regulatory mechanisms and potential clinical applications in the context of male infertility. By examining the latest research, we emphasize the crucial role of extracellular ATP in sperm function and propose future research directions to further.
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Affiliation(s)
- Heran Cao
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Long Li
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Shujuan Liu
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yang Wang
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Xianglin Liu
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Fangxia Yang
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Wuzi Dong
- College of Animal Science and Technology, Northwest A&F University, Yangling, Shaanxi, 712100, China.
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López-González I, Sánchez-Cárdenas C, De la Vega-Beltrán JL, Alvarado-Quevedo B, Ocelotl-Oviedo JP, González-Cota AL, Aldana A, Orta G, Darszon A. ATP increases head volume in capacitated human sperm via a purinergic channel. Biochem Biophys Res Commun 2023; 671:318-326. [PMID: 37327703 DOI: 10.1016/j.bbrc.2023.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 06/02/2023] [Indexed: 06/18/2023]
Abstract
Scanning ion-conductance microscopy allowed us to document an external Ca2+ dependent ATP driven volume increase (ATPVI) in capacitated human sperm heads. We examined the involvement of purinergic receptors (PRs) P2X2R and P2X4R in ATPVI using their co-agonists progesterone and Ivermectin (Iver), and Cu2+, which co-activates P2X2Rs and inhibits P2X4Rs. Iver enhanced ATPVI and Cu2+ and 5BDBD inhibited it, indicating P2X4Rs contributed to this response. Moreover, Cu2+ and 5BDBD inhibited the ATP-induced acrosome reaction (AR) which was enhanced by Iver. ATP increased the concentration of intracellular Ca2+ ([Ca2+]i) in >45% of individual sperm, most of which underwent AR monitored using FM4-64. Our findings suggest that human sperm P2X4R activation by ATP increases [Ca2+]i mainly due to Ca2+ influx which leads to a sperm head volume increase, likely involving acrosomal swelling, and resulting in AR.
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Affiliation(s)
- I López-González
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico.
| | - C Sánchez-Cárdenas
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - J L De la Vega-Beltrán
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - B Alvarado-Quevedo
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - J P Ocelotl-Oviedo
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - A L González-Cota
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - A Aldana
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - G Orta
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico
| | - A Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, Mexico.
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Abstract
Adenosine triphosphate (ATP) serves as the essential source of cellular energy. Over the last two decades, however, ATP has also attracted increasing interest as an extracellular signal that activates purinergic plasma membrane receptors of the P2 family. P2 receptors are divided into two types: ATP-gated nonselective cation channels (P2X) and G protein-coupled receptors (P2Y), the latter being activated by a broad range of purine and pyrimidine nucleotides (ATP, ADP, UTP, and UDP, among others). Purinergic signaling mechanisms are involved in numerous physiological events and pathophysiological conditions. Here, we address the growing body of evidence implicating purinergic signaling in male reproductive system functions. The life-long generation of fertile male germ cells is a highly complex, yet mechanistically poorly understood process. Given the relatively sparse innervation of the testis, spermatogenesis relies on both endocrine control and multi-directional paracrine communication. Therefore, a detailed understanding of such paracrine messengers, including ATP, is crucial to gain mechanistic insight into male reproduction..
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Affiliation(s)
- Nadine Mundt
- Department of Physiology, University of California, San Francisco, San Francisco, CA, United States
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
- Research Training Group 2416 MultiSenses – MultiScales, RWTH Aachen University, Aachen, Germany
- *Correspondence: Nadine Mundt,
| | - Lina Kenzler
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
| | - Marc Spehr
- Department of Chemosensation, Institute for Biology II, RWTH Aachen University, Aachen, Germany
- Research Training Group 2416 MultiSenses – MultiScales, RWTH Aachen University, Aachen, Germany
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4
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Bellezza I, Minelli A. Adenosine in sperm physiology. Mol Aspects Med 2017; 55:102-109. [DOI: 10.1016/j.mam.2016.11.009] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2016] [Revised: 11/23/2016] [Accepted: 11/23/2016] [Indexed: 10/20/2022]
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Thuwanut P, Arya N, Comizzoli P, Chatdarong K. Effect of extracellular adenosine 5'-triphosphate on cryopreserved epididymal cat sperm intracellular ATP concentration, sperm quality, and in vitro fertilizing ability. Theriogenology 2015; 84:702-9. [PMID: 26050612 DOI: 10.1016/j.theriogenology.2015.05.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Revised: 04/30/2015] [Accepted: 05/03/2015] [Indexed: 02/03/2023]
Abstract
Intracellular adenosine 5'-triphosphate (ATP) is essential for supporting sperm function in the fertilization process. During cryopreservation, damage of sperm mitochondrial membrane usually leads to compromised production of intracellular ATP. Recently, extracellular ATP (ATPe) was introduced as a potent activator of sperm motility and fertilizing ability. This study aimed to evaluate (1) levels of intracellular ATP in frozen-thawed epididymal cat sperm after incubation with ATPe and (2) effects of ATPe on epididymal cat sperm parameters after freezing and thawing. Eighteen male cats were included. For each replicate, epididymal sperm from two cats were pooled to one sample (N = 9). Each pooled sample was cryopreserved with the Tris-egg yolk extender into three straws. After thawing, the first and second straws were incubated with 0-, 1.0-, or 2.5-mM ATPe for 10 minutes and evaluated for sperm quality at 10 minutes, 1, 3, and 6 hours after thawing and fertilizing ability. The third straw was evaluated for intracellular ATP concentration in control and with 2.5-mM ATPe treatment. Higher concentration of intracellular sperm ATP was observed in the samples treated with 2.5-mM ATPe compared to the controls (0.339 ± 0.06 μg/2 × 10(6) sperm vs. 0.002 ± 0.003 μg/2 × 10(6) sperm, P ≤ 0.05). In addition, incubation with 2.5-mM ATPe for 10 minutes promoted sperm motility (56.7 ± 5.0 vs. 53.3 ± 4.4%, P ≤ 0.05) and progressive motility (3.1 ± 0.2 vs. 2.8 ± 0.4, P ≤ 0.05), mitochondrial membrane potential (36.4 ± 5.5 vs. 28.7 ± 4.8%, P ≤ 0.05), and blastocyst rate (36.1 ± 7.0 and 28.8 ± 7.4%, P ≤ 0.05) compared with the controls. In contrast, ATPe remarkably interfered acrosome integrity after 6 hours of postthawed incubation. In sum, the present finding that optimal incubation time of postthaw epididymal cat sperm under proper ATPe condition might constitute a rationale for the studies on other endangered wild felids regarding sperm quality and embryo development.
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Affiliation(s)
- Paweena Thuwanut
- Department of Obstetrics, Gynaecology and Reproduction, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand; Center for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, Washington DC, USA
| | - Nlin Arya
- Department of Preclinic and Applied Animal Science, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, Thailand
| | - Pierre Comizzoli
- Center for Species Survival, Smithsonian Conservation Biology Institute, National Zoological Park, Washington DC, USA
| | - Kaywalee Chatdarong
- Department of Obstetrics, Gynaecology and Reproduction, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, Thailand.
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7
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Abstract
Adenosine-5'-triphosphate is released by neuroendocrine, endocrine, and other cell types and acts as an extracellular agonist for ligand-gated P2X cationic channels and G protein-coupled P2Y receptors in numerous organs and tissues, including the endocrine system. The breakdown of ATP by ectonucleotidases not only terminates its extracellular messenger functions, but also provides a pathway for the generation of two additional agonists: adenosine 5'-diphosphate, acting via some P2Y receptors, and adenosine, a native agonist for G protein-coupled adenosine receptors, also expressed in the endocrine system. This article provides a review of purinergic signaling pathways in the hypothalamic magnocellular neurosecretory cells and neurohypophysis, hypothalamic parvocellular neuroendocrine system, adenohypophysis, and effector glands organized in five axes: hypothalamic-pituitary-gonadal, hypothalamic-pituitary-thyroid, hypothalamic-pituitary-adrenal, hypothalamic-pituitary-growth hormone, and hypothalamic-pituitary-prolactin. We attempted to summarize current knowledge of purinergic receptor subtypes expressed in the endocrine system, including their roles in intracellular signaling, hormone secretion, and other cell functions. We also briefly review the release mechanism for adenosine-5'-triphosphate by neuroendocrine, endocrine and surrounding cells, the enzymes involved in adenosine-5'-triphosphate hydrolysis to adenosine-5'-diphosphate and adenosine, and the relevance of this pathway for sequential activation of receptors and termination of signaling.
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8
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Burnstock G. Purinergic signalling in the reproductive system in health and disease. Purinergic Signal 2014; 10:157-87. [PMID: 24271059 PMCID: PMC3944041 DOI: 10.1007/s11302-013-9399-7] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 10/24/2013] [Indexed: 12/16/2022] Open
Abstract
There are multiple roles for purinergic signalling in both male and female reproductive organs. ATP, released as a cotransmitter with noradrenaline from sympathetic nerves, contracts smooth muscle via P2X1 receptors in vas deferens, seminal vesicles, prostate and uterus, as well as in blood vessels. Male infertility occurs in P2X1 receptor knockout mice. Both short- and long-term trophic purinergic signalling occurs in reproductive organs. Purinergic signalling is involved in hormone secretion, penile erection, sperm motility and capacitation, and mucous production. Changes in purinoceptor expression occur in pathophysiological conditions, including pre-eclampsia, cancer and pain.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Centre, University College Medical School, Rowland Hill Street, London, NW3 2PF, UK,
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Lishko PV, Kirichok Y, Ren D, Navarro B, Chung JJ, Clapham DE. The control of male fertility by spermatozoan ion channels. Annu Rev Physiol 2011; 74:453-75. [PMID: 22017176 DOI: 10.1146/annurev-physiol-020911-153258] [Citation(s) in RCA: 252] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ion channels control the sperm ability to fertilize the egg by regulating sperm maturation in the female reproductive tract and by triggering key sperm physiological responses required for successful fertilization such as hyperactivated motility, chemotaxis, and the acrosome reaction. CatSper, a pH-regulated, calcium-selective ion channel, and KSper (Slo3) are core regulators of sperm tail calcium entry and sperm hyperactivated motility. Many other channels had been proposed as regulating sperm activity without direct measurements. With the development of the sperm patch-clamp technique, CatSper and KSper have been confirmed as the primary spermatozoan ion channels. In addition, the voltage-gated proton channel Hv1 has been identified in human sperm tail, and the P2X2 ion channel has been identified in the midpiece of mouse sperm. Mutations and deletions in sperm-specific ion channels affect male fertility in both mice and humans without affecting other physiological functions. The uniqueness of sperm ion channels makes them ideal pharmaceutical targets for contraception. In this review we discuss how ion channels regulate sperm physiology.
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Affiliation(s)
- Polina V Lishko
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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Burnstock G, Fredholm BB, North RA, Verkhratsky A. The birth and postnatal development of purinergic signalling. Acta Physiol (Oxf) 2010; 199:93-147. [PMID: 20345419 DOI: 10.1111/j.1748-1716.2010.02114.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The purinergic signalling system is one of the most ancient and arguably the most widespread intercellular signalling system in living tissues. In this review we present a detailed account of the early developments and current status of purinergic signalling. We summarize the current knowledge on purinoceptors, their distribution and role in signal transduction in various tissues in physiological and pathophysiological conditions.
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Affiliation(s)
- G Burnstock
- Autonomic Neuroscience Centre, Royal Free and University College Medical School, London, UK.
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11
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Banks FC, Calvert RC, Burnstock G. Changing P2X receptor localization on maturing sperm in the epididymides of mice, hamsters, rats, and humans: a preliminary study. Fertil Steril 2010; 93:1415-20. [DOI: 10.1016/j.fertnstert.2009.02.061] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2008] [Revised: 02/11/2009] [Accepted: 02/19/2009] [Indexed: 11/29/2022]
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12
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Rodríguez-Miranda E, Buffone MG, Edwards SE, Ord TS, Lin K, Sammel MD, Gerton GL, Moss SB, Williams CJ. Extracellular adenosine 5'-triphosphate alters motility and improves the fertilizing capability of mouse sperm. Biol Reprod 2008; 79:164-71. [PMID: 18401012 DOI: 10.1095/biolreprod.107.065565] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Extracellular adenosine 5'-triphosphate (ATPe) treatment of human sperm has been implicated in improving in vitro fertilization (IVF) results. We used the mouse model to investigate mechanisms of action of ATPe on sperm. ATPe treatment significantly enhanced IVF success as indicated by both rate of pronuclear formation and percentage cleavage to the 2-cell stage. However, ATPe did not increase the percentage of sperm undergoing spontaneous acrosomal exocytosis nor change the pattern of protein tyrosine phosphorylation normally observed in capacitated sperm. ATPe altered sperm motility parameters; in particular, both noncapacitated and capacitated sperm swam faster and straighter. The percentage of hyperactivated sperm did not increase in capacitated ATPe-treated sperm compared to control sperm. ATPe induced a rapid increase in the level of intracellular calcium that was inhibited by two distinct P2 purinergic receptor inhibitors, confirming that these receptors have an ionotropic role in sperm function. The observed motility changes likely explain, in part, the improved fertilizing capability when ATPe-treated sperm were used in IVF procedures and suggest a mechanism by which ATPe treatment may be beneficial for artificial reproductive techniques.
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Affiliation(s)
- Esmeralda Rodríguez-Miranda
- Department of Obstetrics & Gynecology, Center for Research on Reproduction & Women's Health, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Edwards SE, Buffone MG, Knee GR, Rossato M, Bonanni G, Masiero S, Ferasin S, Gerton GL, Moss SB, Williams CJ. Effects of extracellular adenosine 5'-triphosphate on human sperm motility. Reprod Sci 2008; 14:655-66. [PMID: 18000227 DOI: 10.1177/1933719107306227] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Extracellular adenosine 5'-triphosphate (ATP) previously has been shown to increase the fertilization percentage in human in vitro fertilization (IVF) performed for male factor infertility. The objective of this study is to determine the effects of extracellular adenosine 5'-triphosphate (ATPe) on human sperm function by examining its effects on end points of sperm capacitation. Sperm obtained from healthy volunteers with normal semen parameters, asthenozoospermic men, and cryopreserved samples were incubated in medium with or without 2.5 mM ATPe. The effects of ATPe on acrosomal exocytosis, protein tyrosine phosphorylation, and sperm motility parameters were quantified. Although ATPe did not affect acrosomal exocytosis or protein tyrosine phosphorylation in sperm from healthy donors, it significantly altered several motility parameters, with the largest effects manifested in increased curvilinear velocity and percentage hyperactivation. ATPe similarly affected sperm selected for poor motility and thawed cryopreserved sperm but to a lesser extent than its effects on sperm with normal motility. ATPe increased straight-line velocity and linearity of sperm obtained from asthenozoospermic men. Human sperm motility characteristics are altered by ATPe; this finding may explain its previously reported beneficial effect on human IVF. These results suggest that ATPe could constitute a new therapeutic modality in the treatment of male infertility.
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Affiliation(s)
- Scott E Edwards
- Center for Research on Reproduction & Women's Health, Department of Obstetrics & Gynecology, University of Pennsylvania, Philadelphia, PA, USA
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14
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Rossato M, Ferigo M, Galeazzi C, Foresta C. Estradiol inhibits the effects of extracellular ATP in human sperm by a non genomic mechanism of action. Purinergic Signal 2005; 1:369-75. [PMID: 18404521 PMCID: PMC2096547 DOI: 10.1007/s11302-005-1172-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Revised: 07/07/2005] [Accepted: 07/20/2005] [Indexed: 11/24/2022] Open
Abstract
Steroid hormones, beside their classical genomic mechanism of action, exert rapid, non genomic effects in different cell types. These effects are mediated by still poorly characterized plasma membrane receptors that appear to be distinct from the classic intracellular receptors. In the present study we evaluated the non genomic effects of estradiol (17βE2) in human sperm and its effects on sperm stimulation by extracellular ATP, a potent activator of sperm acrosome reaction. In human sperm 17βE2 induced a rapid increase of intracellular calcium (Ca2+) concentrations dependent on an influx of Ca2+ from the extracellular medium. The monitoring of the plasma membrane potential variations induced by 17βE2 showed that this steroid induces a rapid plasma membrane hyperpolarization that was dependent on the presence of Ca2+ in the extracellular medium since it was absent in Ca2+ free-medium. When sperm were pre-incubated in the presence of the K+ channel inhibitor tetra-ethylammonium, the 17βE2 induced plasma membrane hyperpolarization was blunted suggesting the involvement of K+ channels in the hyperpolarizing effects of 17βE2. Extracellular ATP induced a rapid plasma membrane depolarization followed by acrosome reaction. Sperm pre-incubation with 17βE2 inhibited the effects of extracellular ATP on sperm plasma membrane potential variations and acrosome reaction. The effects of 17βE2 were specific since its inactive steroisomer 17αE2 was inactive. Furthermore the effects of 17βE2 were not inhibited by tamoxifen, an antagonist of the classic 17βE2 intracellular receptor.
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Affiliation(s)
- Marco Rossato
- Department of Medical and Surgical Sciences, Clinica Medica 3, University of Padova, Italy,
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15
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Meizel S. The sperm, a neuron with a tail: 'neuronal' receptors in mammalian sperm. Biol Rev Camb Philos Soc 2005; 79:713-32. [PMID: 15682867 DOI: 10.1017/s1464793103006407] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
A number of plasma membrane receptor types originally thought to be specific to neurons have been found in other somatic cells. More surprisingly, the mammalian sperm and neuron appear to share many of these 'neuronal' receptors. The morphology, chromosome number, genomic activity, and functions of those two cell types are as unlike as any two cells in the body, but they both achieve their highly disparate goals with the aid of a number of the same receptors. Exocytosis in neurons and sperm is essential to the functions of these cells and is strongly influenced by similar receptors. 'Neuronal' receptor types in sperm may also play a role in the control of sperm motility (a function of course not shared by neurons). This review will consider the evidence for the presence of sperm plasma membrane 'neuronal' receptors and for their significance to mammalian sperm function. The persuasiveness of the evidence varies depending on the receptor being considered, but there is strong experimental support for the presence and importance of a number of 'neuronal' receptors in sperm.
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Affiliation(s)
- Stanley Meizel
- Department of Cell Biology and Human Anatomy, University of California, Davis School of Medicine, Davis, California, USA.
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16
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Darszon A, Nishigaki T, Wood C, Treviño CL, Felix R, Beltrán C. Calcium Channels and Ca2+ Fluctuations in Sperm Physiology. INTERNATIONAL REVIEW OF CYTOLOGY 2005; 243:79-172. [PMID: 15797459 DOI: 10.1016/s0074-7696(05)43002-8] [Citation(s) in RCA: 124] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Generating new life in animals by sexual reproduction depends on adequate communication between mature and competent male and female gametes. Ion channels are instrumental in the dialogue between sperm, its environment, and the egg. The ability of sperm to swim to the egg and fertilize it is modulated by ion permeability changes induced by environmental cues and components of the egg outer layer. Ca(2+) is probably the key messenger in this information exchange. It is therefore not surprising that different Ca(2+)-permeable channels are distinctly localized in these tiny specialized cells. New approaches to measure sperm currents, intracellular Ca(2+), membrane potential, and intracellular pH with fluorescent probes, patch-clamp recordings, sequence information, and heterologous expression are revealing how sperm channels participate in fertilization. Certain sperm ion channels are turning out to be unique, making them attractive targets for contraception and for the discovery of novel signaling complexes.
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Affiliation(s)
- Alberto Darszon
- Department of Developmental Genetics and Molecular Physiology, Institute of Biotechnology, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico 62210
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17
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Sakai N, Sawada H, Yokosawa H. Extracellular ubiquitin system implicated in fertilization of the ascidian, Halocynthia roretzi: isolation and characterization. Dev Biol 2004; 264:299-307. [PMID: 14623250 DOI: 10.1016/j.ydbio.2003.07.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The ubiquitin-proteasome system is essential for intracellular protein degradation, but there are few studies of this system in the extracellular milieu. Recently, we reported that a 70-kDa sperm receptor, HrVC70, on the vitelline coat is ubiquitinated and then degraded by the sperm proteasome during fertilization of the ascidian, Halocynthia roretzi. Here, we investigated the mechanism of extracellular ubiquitination. The HrVC70-ubiquitinating enzyme activity was found to be released from the activated sperm during the fertilization process. This enzyme was purified from an activated sperm exudate, by chromatography on DEAE-cellulose and ubiquitin-agarose columns, and by glycerol density gradient centrifugation. The molecular mass of the enzyme was estimated to be 700 kDa. The purified enzyme requires CaCl2 and MgATP for activity, and is active in seawater. The purified enzyme preparation, but not the crude enzyme preparation, showed narrow substrate specificity to HrVC70. Moreover, ATP and ubiquitin are released from the activated sperm to the surrounding seawater during fertilization. These results indicate that ascidian sperm release a novel extracellular ubiquitinating enzyme system together with ATP and ubiquitin during penetration of the vitelline coat of the egg, which catalyzes the ubiquitination of the HrVC70, an essential component of ascidian fertilization.
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Affiliation(s)
- Naoyuki Sakai
- Department of Biochemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
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18
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Burnstock G, Knight GE. Cellular Distribution and Functions of P2 Receptor Subtypes in Different Systems. INTERNATIONAL REVIEW OF CYTOLOGY 2004; 240:31-304. [PMID: 15548415 DOI: 10.1016/s0074-7696(04)40002-3] [Citation(s) in RCA: 573] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This review is aimed at providing readers with a comprehensive reference article about the distribution and function of P2 receptors in all the organs, tissues, and cells in the body. Each section provides an account of the early history of purinergic signaling in the organ?cell up to 1994, then summarizes subsequent evidence for the presence of P2X and P2Y receptor subtype mRNA and proteins as well as functional data, all fully referenced. A section is included describing the plasticity of expression of P2 receptors during development and aging as well as in various pathophysiological conditions. Finally, there is some discussion of possible future developments in the purinergic signaling field.
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Affiliation(s)
- Geoffrey Burnstock
- Autonomic Neuroscience Institute, Royal Free and University College Medical School, London NW3 2PF, United Kingdom
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19
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Luria A, Rubinstein S, Lax Y, Breitbart H. Extracellular adenosine triphosphate stimulates acrosomal exocytosis in bovine spermatozoa via P2 purinoceptor. Biol Reprod 2002; 66:429-37. [PMID: 11804959 DOI: 10.1095/biolreprod66.2.429] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
The presence of ATP in the genital tract fluid of mammals provokes questions regarding its function in the fertilization process. We investigated the effect of extracellular ATP (ATPe) on the activation of bovine spermatozoa. A signal transduction mechanism for ATP involving the receptor-mediated release of second messengers is described. Treatment of spermatozoa with ATP, uridine triphosphate (UTP), or 2-methylthio-ATP resulted in a concentration-dependent increase of acrosomal exocytosis, whereas treatment with either AMP or adenosine induced little exocytosis. This suggested that the receptor involved is of the P2 and not the P1 type. Several lines of evidence also suggest that the ATP purinoceptor is of the P2y and not the P2x type. First, the acrosome reaction was induced by the P2y-agonists ATP, UTP, or 2-methylthio-ATP, but no effects were shown by the P2x-agonists alpha,beta-methylene-ATP or beta,gamma-methylene-ATP. Second, ATP-induced acrosomal exocytosis was inhibited by the P2y antagonists, but not by the P2x antagonists. Third, enhanced Ca2+ uptake into the cells was observed with ATP and 2-methylthio-ATP, but not with beta,gamma-methylene-ATP. Additionally, ATP induced elevation of intracellular Ca2+ and cAMP, and the effect on cAMP was predominantly enhanced by including Ca2+ and the Ca2+-ionophore A23187 in the incubation medium. Extracellular ATP also activates protein kinase Calpha (PKCalpha), and the acrosome reaction, stimulated by ATPe, is inhibited by a PKC-specific inhibitor. In summary, we suggest that ATPe activates the P2 purinoceptor that elevates [Ca2+]i, which leads to PKCalpha activation and culminates in acrosomal exocytosis.
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Affiliation(s)
- Ayala Luria
- Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan 52900, Israel
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20
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Na+-permeable channels of human sperm membrane reassembled into giant liposome. ACTA ACUST UNITED AC 2001. [DOI: 10.1007/bf02900683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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21
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Rossato M, Merico M, Bettella A, Bordon P, Foresta C. Extracellular ATP stimulates estradiol secretion in rat Sertoli cells in vitro: modulation by external sodium. Mol Cell Endocrinol 2001; 178:181-7. [PMID: 11403908 DOI: 10.1016/s0303-7207(01)00426-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
In this study, we examined the effects of extracellular ATP (ATPe) on [Ca(2+)](i), [Na(+)](i), plasma membrane potential changes and estradiol secretion in rat Sertoli cells. ATPe caused a rapid rise of [Ca(2+)](i) with an initial spike followed by a long lasting plateau. The first rapid spike was dependent on the release of Ca(2+) from internal stores as it also occurred in Ca(2+)-free medium while the long lasting plateau phase was dependent on Ca(2+) influx from the external medium. ATPe stimulated a rapid plasma membrane depolarization that was dependent on an influx of Na(+) from the external medium as demonstrated by plasma membrane potential monitoring in Na(+)-free medium and by [Na(+)](i) measurement with the Na(+)-sensitive fluorescent dye SBFI. ATPe stimulated estradiol secretion in a dose dependent manner and was fully dependent on the presence of Na(+) in the external medium while the presence of Ca(2+) was not necessary. Among the different nucleotides tested, only ATP, ATP-5'-[gamma-thio]triphosphate, UTP, alpha,beta-methylene-ATP were effective in stimulating estradiol secretion. These results demonstrate that rat Sertoli cells possess P2-purinergic receptors belonging to the P2X and P2Y subfamily which activation induces [Ca(2+)](i) and [Na(+)](i) rise and Na(+)-dependent plasma membrane depolarization leading to estradiol secretion.
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Affiliation(s)
- M Rossato
- Department of Medical and Surgical Sciences, Clinica Medica 3, University of Padova, Via Ospedale 105, 35128, Padova, Italy
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22
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Perregaux DG, Labasi J, Laliberte R, Stam E, Solle M, Koller B, Griffiths R, Gabel CA. Interleukin-1? posttranslational processing?exploration of P2X7 receptor involvement. Drug Dev Res 2001. [DOI: 10.1002/ddr.1175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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23
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Solle M, Labasi J, Perregaux DG, Stam E, Petrushova N, Koller BH, Griffiths RJ, Gabel CA. Altered cytokine production in mice lacking P2X(7) receptors. J Biol Chem 2001; 276:125-32. [PMID: 11016935 DOI: 10.1074/jbc.m006781200] [Citation(s) in RCA: 732] [Impact Index Per Article: 31.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The P2X(7) receptor (P2X(7)R) is an ATP-gated ion channel expressed by monocytes and macrophages. To directly address the role of this receptor in interleukin (IL)-1 beta post-translational processing, we have generated a P2X(7)R-deficient mouse line. P2X(7)R(-/-) macrophages respond to lipopolysaccharide and produce levels of cyclooxygenase-2 and pro-IL-1 beta comparable with those generated by wild-type cells. In response to ATP, however, pro-IL-1 beta produced by the P2X(7)R(-/-) cells is not externalized or activated by caspase-1. Nigericin, an alternate secretion stimulus, promotes release of 17-kDa IL-1 beta from P2X(7)R(-/-) macrophages. In response to in vivo lipopolysaccharide injection, both wild-type and P2X(7)R(-/-) animals display increases in peritoneal lavage IL-6 levels but no detectable IL-1. Subsequent ATP injection to wild-type animals promotes an increase in IL-1, which in turn leads to additional IL-6 production; similar increases did not occur in ATP-treated, LPS-primed P2X(7)R(-/-) animals. Absence of the P2X(7)R thus leads to an inability of peritoneal macrophages to release IL-1 in response to ATP. As a result of the IL-1 deficiency, in vivo cytokine signaling cascades are impaired in P2X(7)R-deficient animals. Together these results demonstrate that P2X(7)R activation can provide a signal that leads to maturation and release of IL-1 beta and initiation of a cytokine cascade.
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Affiliation(s)
- M Solle
- Department of Respiratory, Allergy, Immunology, Inflammation, and Infectious Diseases, Pfizer Inc., Groton, Connecticut 06340, USA
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24
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HONDO E, KOBAYASHI T, AITA T, MANABE N, KITAMURA N, YAMADA J, NAMBA Y, NAGAHAMA Y, KISO Y. Molecular Cloning and Expression of Suppressor of Potassium Transport Defect 3 (SKD3) in Rat Testis. J Reprod Dev 2001. [DOI: 10.1262/jrd.47.173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Eiichi HONDO
- Department of Veterinary Anatomy, Faculty of Agriculture, Yamaguchi University
| | - Tohru KOBAYASHI
- Laboratory of Reproductive Biology, National Institute of Basic Biology
| | - Tsunehiko AITA
- Department of Veterinary Anatomy, Obihiro University of Agriculture & Veterinary Medicine
| | - Noboru MANABE
- Unit of Anatomy and Cell Biology, Department of Animal Sciences, Kyoto University
| | - Nobuo KITAMURA
- Department of Veterinary Anatomy, Obihiro University of Agriculture & Veterinary Medicine
| | - Junzo YAMADA
- Department of Veterinary Anatomy, Obihiro University of Agriculture & Veterinary Medicine
| | - Yasuharu NAMBA
- Department of Veterinary Anatomy, Faculty of Agriculture, Yamaguchi University
| | | | - Yasuo KISO
- Department of Veterinary Anatomy, Faculty of Agriculture, Yamaguchi University
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25
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Abstract
Fertilization is a matter of life or death. In animals of sexual reproduction, the appropriate communication between mature and competent male and female gametes determines the generation of a new individual. Ion channels are key elements in the dialogue between sperm, its environment, and the egg. Components from the outer layer of the egg induce ion permeability changes in sperm that regulate sperm motility, chemotaxis, and the acrosome reaction. Sperm are tiny differentiated terminal cells unable to synthesize protein and difficult to study electrophysiologically. Thus understanding how sperm ion channels participate in fertilization requires combining planar bilayer techniques, in vivo measurements of membrane potential, intracellular Ca2+ and intracellular pH using fluorescent probes, patch-clamp recordings, and molecular cloning and heterologous expression. Spermatogenic cells are larger than sperm and synthesize the ion channels that will end up in mature sperm. Correlating the presence and cellular distribution of various ion channels with their functional status at different stages of spermatogenesis is contributing to understand their participation in differentiation and in sperm physiology. The multi-faceted approach being used to unravel sperm ion channel function and regulation is yielding valuable information about the finely orchestrated events that lead to sperm activation, induction of the acrosome reaction, and in the end to the miracle of life.
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Affiliation(s)
- A Darszon
- Departamento de Genética y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Morelos, Mexico
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26
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An Intimate Biochemistry: Egg-Regulated Acrosome Reactions of Mammalian Sperm. ACTA ACUST UNITED AC 1999. [DOI: 10.1016/s1064-2722(08)60021-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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27
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Perregaux DG, Gabel CA. Human monocyte stimulus-coupled IL-1beta posttranslational processing: modulation via monovalent cations. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:C1538-47. [PMID: 9843715 DOI: 10.1152/ajpcell.1998.275.6.c1538] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lipopolysaccharide-activated human monocytes produce prointerleukin (pro-IL)-1beta but release little of this inflammatory cytokine as the biologically active species. Efficient externalization of mature 17-kDa cytokine requires that the activated monocytes encounter a secondary stimulus such as ATP. To identify cation requirements of the ATP-induced process, lipopolysaccharide-activated monocytes were treated with ATP in media containing different Cl- salts or sucrose. Media devoid of Na+ did not support IL-1beta processing. Titration of NaCl into choline chloride- or sucrose-based media restored 17-kDa IL-1beta production. Na+ replacement, however, was not sufficient to support ATP-induced production of 17-kDa IL-1beta in the presence of >/=37 mM extracellular K+ or Li+. Inhibition by K+ suggests that efflux of this cation is a necessary component of the stimulus-coupled response. The inhibitory effect achieved by Na+ depletion is not due to inactivation of the ATP receptor and is distinct from a caspase-1 inhibitor. Stimulus-coupled IL-1beta posttranslational processing, therefore, requires extracellular Na+ for a step downstream of the initiating stimulus but preceding caspase-1 activation.
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Affiliation(s)
- D G Perregaux
- Pfizer Central Research, Groton, Connecticut 06340, USA
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28
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Chan HC, Wu WL, Sun YP, Leung PS, Wong TP, Chung YW, So SC, Zhou TS, Yan YC. Expression of sperm Ca2+-activated K+ channels in Xenopus oocytes and their modulation by extracellular ATP. FEBS Lett 1998; 438:177-82. [PMID: 9827541 DOI: 10.1016/s0014-5793(98)01298-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Ionic fluxes across the sperm membrane have been shown to be important in the initiating process of sperm activation and gamete interaction; however, electrophysiological investigation of the ion channels involved has been precluded by the small size of the sperm, especially in mammalian species. In the present study sperm ion channels were expressed in Xenopus oocytes by injection of RNAs of spermatogenic cells isolated from the rat testes. The RNA-injected oocytes responded to ATP, a factor known to regulate sperm activation, with the activation of an outwardly rectifying whole-cell current which was dependent on K+ concentrations and inhibitable by K+ channel blockers, charybdotoxin (CTX) and tetraethylammonium (TEA). The ATP-induced current could be mimicked by a Ca2+ ionophore but suppressed by a Ca2+ chelator applied intracellularly, indicating a Ca2+ dependence of the current. Single-channel measurements on RNA-injected oocytes revealed channels of large conductance which could be blocked by CTX and TEA. Co-injection of germ cell RNAs with the antisense RNA for a mouse gene encoding slowpoke 'Maxi' Ca2+-activated K+ channels resulted in significant reduction of the ATP- and ionomycin-induced current. The expression of the 'Maxi' Ca2+-activated K+ channels in sperm collected from the rat epididymis was also confirmed by Western blot analysis. These results suggest that sperm possess Ca2+-activated K+ channels which may be involved in the process of sperm activation.
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Affiliation(s)
- H C Chan
- Department of Physiology, Faculty of Medicine, The Chinese University of Hong Kong, Shatin.
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29
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30
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Wu WL, So SC, Sun YP, Chung YW, Grima J, Wong PY, Yan YC, Chan HC. Functional expression of P2U receptors in rat spermatogenic cells: dual modulation of a Ca(2+)-activated K+ channel. Biochem Biophys Res Commun 1998; 248:728-32. [PMID: 9703995 DOI: 10.1006/bbrc.1998.9051] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous study has demonstrated functional expression of a sperm Ca(2+)-activated K+ channel in Xenopus oocytes injected with RNAs from the rat testes. Using the same expression system, the present study investigated the specific purinoceptor subtype involved in mediating the effect of extracellular ATP. The effect of ATP on an outwardly rectifying current, previously demonstrated to be mediated by a "Maxi" Ca(2+)-activated K+ channel, was compared to the current responses to different nucleotides using the two-electrode voltage-clamp technique. An order of relative effectiveness appeared to be UTP > ATP > ADP > adenosine, consistent with the pharmacological classification of P2U receptors. ATP was also found to exert an inhibitory effect on the Ca(2+)-activated K+ current, elicited by the Ca2+ ionophore ionomycin. A similar inhibitory effect was observed with UTP, again suggesting the involvement of P2U receptor. RT-PCR study also confirmed the expression of P2U receptor mRNA in isolated spermatogenic cells. The present results demonstrate the expression of P2U receptor and its dual role, both stimulatory and inhibitory, in the modulation of the Ca(2+)-activated K+ channel in spermatogenic cells. The present finding lends support to an important role of extracellular ATP in sperm functions.
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Affiliation(s)
- W L Wu
- Department of Physiology, Faculty of Medicine, Chinese University of Hong Kong, Shatin, Hong Kong, China
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31
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Florman HM, Arnoult C, Kazam IG, Li C, O'Toole CM. A perspective on the control of mammalian fertilization by egg-activated ion channels in sperm: a tale of two channels. Biol Reprod 1998; 59:12-6. [PMID: 9674987 DOI: 10.1095/biolreprod59.1.12] [Citation(s) in RCA: 143] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Affiliation(s)
- H M Florman
- Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, MA 02111, USA.
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32
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Tulsiani DR, Abou-Haila A, Loeser CR, Pereira BM. The biological and functional significance of the sperm acrosome and acrosomal enzymes in mammalian fertilization. Exp Cell Res 1998; 240:151-64. [PMID: 9596988 DOI: 10.1006/excr.1998.3943] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mammalian spermatozoon undergoes continuous modifications during spermatogenesis, maturation in the epididymis, and capacitation in the female reproductive tract. Only the capacitated spermatozoa are capable of binding the zona-intact egg and undergoing the acrosome reaction. The fertilization process is a net result of multiple molecular events which enable ejaculated spermatozoa to recognize and bind to the egg's extracellular coat, the zona pellucida (ZP). Sperm-egg interaction is a species-specific event which is initiated by the recognition and binding of complementary molecule(s) present on sperm plasma membrane (receptor) and the surface of the ZP (ligand). This is a carbohydrate-mediated event which initiates a signal transduction cascade resulting in the exocytosis of acrosomal contents. This step is believed to be a prerequisite which enables the acrosome reacted spermatozoa to penetrate the ZP and fertilize the egg. This review focuses on the formation and contents of the sperm acrosome as well as the mechanisms underlying the induction of the acrosome reaction. Special emphasis has been laid on the synthesis, processing, substrate specificity, and mechanism of action of the acid glycohydrolases present within the acrosome. The hydrolytic action of glycohydrolases and proteases released at the site of sperm-zona binding, along with the enhanced thrust generated by the hyperactivated beat pattern of the bound spermatozoon, are important factors regulating the penetration of ZP. We have discussed the most recent studies which have attempted to explain signal transduction pathways leading to the acrosomal exocytosis.
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Affiliation(s)
- D R Tulsiani
- Center for Reproductive Biology Research, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2633, USA
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33
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Arnoult C, Lemos JR, Florman HM. Voltage-dependent modulation of T-type calcium channels by protein tyrosine phosphorylation. EMBO J 1997; 16:1593-9. [PMID: 9130704 PMCID: PMC1169763 DOI: 10.1093/emboj/16.7.1593] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
A T-type Ca2+ channel is expressed during differentiation of the male germ lineage in the mouse and is retained in sperm, where is it activated by contact with the the egg's extracellular matrix and controls sperm acrosomal exocytosis. Here, we examine the regulation of this Ca2+ channel in dissociated spermatogenic cells from the mouse using the whole-cell patch-clamp technique. T currents were enhanced, or facilitated, after strong depolarizations or high frequency stimulation. Voltage-dependent facilitation increased the Ca2+ current by an average of 50%. The same facilitation is produced by antagonists of protein tyrosine kinase activity. Conversely, antagonists of tyrosine phosphatase activity block voltage-dependent facilitation of the current. These data are consistent with the presence of a two-state model, in which T channels are maintained in a low (or zero) conductance state by tonic tyrosine phosphorylation and can be activated to a high conductance state by a tyrosine phosphatase activity. The positive and negative modulation of this channel by the tyrosine phosphorylation state provides a plausible mechanism for the control of sperm activity during the early stages of mammalian fertilization.
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Affiliation(s)
- C Arnoult
- Department of Anatomy and Cellular Biology, Tufts University School of Medicine, Boston, MA 02111, USA
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34
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Bhagwat SS, Williams M. P2 purine and pyrimidine receptors: emerging superfamilies of G-protein-coupled and ligand-gated ion channel receptors. Eur J Med Chem 1997. [DOI: 10.1016/s0223-5234(97)83970-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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