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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Mendoza-Sánchez JE, Rodríguez-Tobón A, Arenas-Ríos E, Orta-Salazar GJ, León-Galván MA, Treviño Santa Cruz CL, Chávez JC. Sperm calcium flux and membrane potential hyperpolarization observed in the Mexican big-eared bat Corynorhinus mexicanus. J Exp Biol 2023; 226:286150. [PMID: 36541225 PMCID: PMC10086540 DOI: 10.1242/jeb.244878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022]
Abstract
Mammalian sperm capacitation involves biochemical and physiological changes, such as an increase in intracellular calcium ion concentration ([Ca2+]i), hyperpolarization of the plasma membrane potential and sperm hyperactivation, among others. These changes provide sperm with the ability to fertilize. In the bat Corynorhinus mexicanus, there is an asynchrony between spermatogenesis and sperm storage in the male with the receptivity of the female. For instance, in C. mexicanus, spermatogenesis occurs before the reproductive season. During the reproductive period, sperm are stored in the epididymis for a few months and the testis undergoes a regression, indicating low or almost null sperm production. Therefore, it is unclear whether the elements necessary for sperm fertilization success undergo maturation or preparation during epididymis storage. Here, we characterized pH-sensitive motility hyperactivation and Ca2+ influx in sperm, regulated by alkalinization and progesterone. In addition, by electrophysiological recordings, we registered currents that were stimulated by alkalinization and inhibited by RU1968 (a CatSper-specific inhibitor), strongly suggesting that these currents were evoked via CatSper, a sperm Ca2+-specific channel indispensable for mammalian fertilization. We also found hyperpolarization of the membrane potential, such as in other mammalian species, which increased according to the month of capture, reaching the biggest hyperpolarization during the mating season. In conclusion, our results suggest that C. mexicanus sperm have functional CatSper and undergo a capacitation-like process such as in other mammals, particularly Ca2+ influx and membrane potential hyperpolarization.
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Affiliation(s)
- José Edwin Mendoza-Sánchez
- Doctorado en Biología Experimental, Universidad Autónoma Metropolitana, Iztapalapa, 09310 Ciudad de México, México
| | - Ahiezer Rodríguez-Tobón
- Laboratorio de Biología y Ecología de Mamíferos, Universidad Autónoma Metropolitana, Iztapalapa, 09310 Ciudad de México, México
| | - Edith Arenas-Ríos
- Laboratorio de Morfofisiología y Bioquímica del Espermatozoide, Universidad Autónoma Metropolitana, Iztapalapa, 09310 Ciudad de México, México
| | - Gerardo J Orta-Salazar
- Consorcio de Fisiología del Espermatozoide, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, 62210 Morelos, México
| | - Miguel A León-Galván
- Laboratorio de Biología y Ecología de Mamíferos, Universidad Autónoma Metropolitana, Iztapalapa, 09310 Ciudad de México, México
| | - Claudia L Treviño Santa Cruz
- Consorcio de Fisiología del Espermatozoide, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, 62210 Morelos, México
| | - Julio C Chávez
- Consorcio de Fisiología del Espermatozoide, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, 62210 Morelos, México
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3
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Taiwo BG, Frettsome-Hook RL, Taylor AE, Correia JN, Lefievre L, Publicover SJ, Conner SJ, Kirkman-Brown JC. Complex combined steroid mix of the female tract modulates human sperm. Reprod Biol 2021; 21:100561. [PMID: 34619633 DOI: 10.1016/j.repbio.2021.100561] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/04/2021] [Accepted: 09/08/2021] [Indexed: 11/29/2022]
Abstract
Human spermatozoa interact with a complex biochemical environment in the female reproductive tract en route to the site of fertilisation. Ovarian follicular fluid contributes to this complex milieu and is known to contain steroids such as progesterone, whose effects on sperm physiology have been widely characterised. We have previously reported that progesterone stimulates intracellular calcium concentration ([Ca2+]i) signalling and acrosome reaction in human spermatozoa. To characterise the effects of the unified complete follicular fluid steroid hormone complement on human spermatozoa, a comprehensive, data-based, 'physiological standard' steroid hormone balance of follicular fluid (shFF) was created from individual constituents. shFF induced a rapid biphasic [Ca2+]i elevation in human spermatozoa. Using population fluorimetry, we compared [Ca2+]i signal amplitude in cells exposed to serial applications of shFF (6 steps from 10-5X up to 1X shFF) with responses to the equivalent progesterone component alone (6 steps from 135 pM - 13.5μM). Threshold for the response to shFF was right-shifted (≈10-fold) compared to progesterone alone, but the maximum response to shFF was greatly enhanced. An acrosome reaction assay was used to assess functional effects of shFF-induced sperm calcium signalling. shFF as well as progesterone-treated spermatozoa showed a significant increase in % acrosome reaction (P < 0.01). All of this evidence suggests the modulation of progesterone-mediated responses by other follicular fluid steroids.
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Affiliation(s)
- Benjamin Gbenro Taiwo
- Centre for Human Reproductive Science (ChRS), Institute of Metabolism and Systems Research, College of Medical & Dental Sciences, University of Birmingham, United Kingdom; Birmingham Women's Fertility Centre, Birmingham Women's Hospital, Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham, United Kingdom
| | - Rebecca Louise Frettsome-Hook
- Centre for Human Reproductive Science (ChRS), Institute of Metabolism and Systems Research, College of Medical & Dental Sciences, University of Birmingham, United Kingdom; Birmingham Women's Fertility Centre, Birmingham Women's Hospital, Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham, United Kingdom
| | - Angela Elizabeth Taylor
- Centre for Human Reproductive Science (ChRS), Institute of Metabolism and Systems Research, College of Medical & Dental Sciences, University of Birmingham, United Kingdom
| | - João Natalino Correia
- Centre for Human Reproductive Science (ChRS), Institute of Metabolism and Systems Research, College of Medical & Dental Sciences, University of Birmingham, United Kingdom
| | - Linda Lefievre
- Centre for Human Reproductive Science (ChRS), Institute of Metabolism and Systems Research, College of Medical & Dental Sciences, University of Birmingham, United Kingdom
| | | | - Sarah Jayne Conner
- Centre for Human Reproductive Science (ChRS), Institute of Metabolism and Systems Research, College of Medical & Dental Sciences, University of Birmingham, United Kingdom; Birmingham Women's Fertility Centre, Birmingham Women's Hospital, Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham, United Kingdom
| | - Jackson Carl Kirkman-Brown
- Centre for Human Reproductive Science (ChRS), Institute of Metabolism and Systems Research, College of Medical & Dental Sciences, University of Birmingham, United Kingdom; Birmingham Women's Fertility Centre, Birmingham Women's Hospital, Birmingham Women's and Children's Hospital NHS Foundation Trust, Birmingham, United Kingdom.
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4
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Jeschke JK, Biagioni C, Schierling T, Wagner IV, Börgel F, Schepmann D, Schüring A, Kulle AE, Holterhus PM, von Wolff M, Wünsch B, Nordhoff V, Strünker T, Brenker C. The Action of Reproductive Fluids and Contained Steroids, Prostaglandins, and Zn 2+ on CatSper Ca 2+ Channels in Human Sperm. Front Cell Dev Biol 2021; 9:699554. [PMID: 34381781 PMCID: PMC8350739 DOI: 10.3389/fcell.2021.699554] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/23/2021] [Indexed: 12/16/2022] Open
Abstract
The sperm-specific Ca2+ channel CatSper registers chemical cues that assist human sperm to fertilize the egg. Prime examples are progesterone and prostaglandin E1 that activate CatSper without involving classical nuclear and G protein-coupled receptors, respectively. Here, we study the action of seminal and follicular fluid as well of the contained individual prostaglandins and steroids on the intracellular Ca2+ concentration of sperm from donors and CATSPER2-deficient patients that lack functional CatSper channels. We show that any of the reproductive steroids and prostaglandins evokes a rapid Ca2+ increase that invariably rests on Ca2+ influx via CatSper. The hormones compete for the same steroid- and prostaglandin-binding site to activate the channel, respectively. Analysis of the hormones’ structure–activity relationship highlights their unique pharmacology in sperm and the chemical features determining their effective properties. Finally, we show that Zn2+ suppresses the action of steroids and prostaglandins on CatSper, which might prevent premature prostaglandin activation of CatSper in the ejaculate, aiding sperm to escape from the ejaculate into the female genital tract. Altogether, our findings reinforce that human CatSper serves as a promiscuous chemosensor that enables sperm to probe the varying hormonal microenvironment prevailing at different stages during their journey across the female genital tract.
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Affiliation(s)
- Janice K Jeschke
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Cristina Biagioni
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Tobias Schierling
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Isabel Viola Wagner
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany.,Department of Pediatrics, University Hospital Lübeck, University of Lübeck, Lübeck, Germany
| | - Frederik Börgel
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Dirk Schepmann
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Andreas Schüring
- UKM Kinderwunschzentrum, University Hospital Münster, Münster, Germany
| | - Alexandra E Kulle
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics, Christian-Albrechts-University, Kiel, Germany
| | - Paul Martin Holterhus
- Division of Pediatric Endocrinology and Diabetes, Department of Pediatrics, Christian-Albrechts-University, Kiel, Germany
| | - Michael von Wolff
- Division of Gynecological Endocrinology and Reproductive Medicine, University Women's Hospital, Bern, Switzerland
| | - Bernhard Wünsch
- Institute of Pharmaceutical and Medicinal Chemistry, University of Münster, Münster, Germany
| | - Verena Nordhoff
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Timo Strünker
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany.,Cells in Motion Interfaculty Centre, University of Münster, Münster, Germany
| | - Christoph Brenker
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
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Mata-Martínez E, Sánchez-Tusie AA, Darszon A, Mayorga LS, Treviño CL, De Blas GA. Epac activation induces an extracellular Ca 2+ -independent Ca 2+ wave that triggers acrosome reaction in human spermatozoa. Andrology 2021; 9:1227-1241. [PMID: 33609309 DOI: 10.1111/andr.12989] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/10/2021] [Accepted: 02/17/2021] [Indexed: 01/02/2023]
Abstract
BACKGROUND The signaling pathways of the intracellular second messengers cAMP and Ca2+ play a crucial role in numerous physiological processes in human spermatozoa. One such process is the acrosome reaction (AR), which is necessary for spermatozoa to traverse the egg envelope and to expose a fusogenic membrane allowing the egg-sperm fusion. Progesterone and zona pellucida elicit an intracellular Ca2+ increase that is needed for the AR in the mammalian spermatozoa. This increase is mediated by an initial Ca2+ influx but also by a release from intracellular Ca2+ stores. It is known that intracellular Ca2+ stores play a central role in the regulation of [Ca2+ ]i and in the generation of complex Ca2+ signals such as oscillations and waves. In the human spermatozoa, it has been proposed that the cAMP analog and specific agonist of Epac 8-(p-chlorophenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate (2'-O-Me-cAMP) elicits an intracellular Ca2+ release involved in the AR. OBJECTIVE To identify the molecular entities involved in the Ca2+ mobilization triggered by 2'-O-Me-cAMP in human spermatozoa. MATERIALS AND METHODS In capacitated human spermatozoa, we monitored Ca2+ dynamics and the occurrence of the AR in real time using Fluo 3-AM and FM4-64 in a Ca2+ -free medium. RESULTS Epac activation by 2'-O-Me-cAMP induced a Ca2+ wave that started in the midpiece and propagated to the acrosome region. This Ca2+ response was sensitive to rotenone, CGP, xestospongin, NED-19, and thapsigargin, suggesting the participation of different ion transporters (mitochondrial complex I and Na+ /Ca2+ exchanger, inositol 3-phosphate receptors, two-pore channels and internal store Ca2+ -ATPases). DISCUSSION Our results suggest that Epac activation promotes a dynamic crosstalk between three different intracellular Ca2+ stores: the mitochondria, the redundant nuclear envelope, and the acrosome. CONCLUSION The Ca2+ wave triggered by Epac activation is necessary to induce the AR and to enhance the flagellar beat.
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Affiliation(s)
- Esperanza Mata-Martínez
- Laboratorio de Fusión de Membranas y Exocitosis Acrosomal, Instituto de Histología y Embriología Dr. Mario H. Burgos (IHEM), Universidad Nacional de Cuyo, CONICET, Mendoza, Argentina
| | - Ana Alicia Sánchez-Tusie
- Laboratorio de Fisiología Celular y Molecular, Departamento de Investigación Biomédica, Facultad de Medicina, Universidad Autónoma de Querétaro, México
| | - Alberto Darszon
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Morelos, México
| | - Luis S Mayorga
- Laboratorio de Fusión de Membranas y Exocitosis Acrosomal, Instituto de Histología y Embriología Dr. Mario H. Burgos (IHEM), Universidad Nacional de Cuyo, CONICET, Mendoza, Argentina.,Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Claudia L Treviño
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Morelos, México
| | - Gerardo A De Blas
- Laboratorio de Fusión de Membranas y Exocitosis Acrosomal, Instituto de Histología y Embriología Dr. Mario H. Burgos (IHEM), Universidad Nacional de Cuyo, CONICET, Mendoza, Argentina.,Laboratorio de Teleanálisis e Investigación Traslacional, Área Farmacología, Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina
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Vieira LA, Diana A, Soriano-Úbeda C, Matás C. Selection of Boar Sperm by Reproductive Biofluids as Chemoattractants. Animals (Basel) 2020; 11:E53. [PMID: 33396764 DOI: 10.3390/ani11010053] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2020] [Accepted: 12/21/2020] [Indexed: 12/29/2022] Open
Abstract
Simple Summary Both in natural breeding and some assisted reproduction technologies, spermatozoa are deposited into the uterus. The journey the spermatozoa must take from the place of semen deposition to the fertilization site is long, hostile, and selective of the best spermatozoa. For the fertilization to succeed, spermatozoa are guided by chemical stimuli (chemoattractants) to the fertilization site, mainly secreted by the oocyte, cumulus cells, and other substances poured into the oviduct in the periovulatory period. This work studied some sources of chemotactic factors and their action on spermatozoa functionality in vitro, including the fertility. A special chemotactic chamber for spermatozoa selection was designed which consists of two wells communicated by a tube. The spermatozoa are deposited in well A, and the chemoattractants in well B. This study focuses on the use of follicular fluid (FF), periovulatory oviductal fluid (pOF), conditioned medium from the in vitro maturation of oocytes (CM), and progesterone (P4) as chemoattractants to sperm. The chemotactic potential of these substances is also investigated as related to their action on CatSper which is a calcium channel in the spermatozoa known to be sensitive to chemoattractants and essential for motility. Abstract Chemotaxis is a spermatozoa guidance mechanism demonstrated in vitro in several mammalian species including porcine. This work focused on follicular fluid (FF), periovulatory oviductal fluid (pOF), the medium surrounding oocytes during in vitro maturation (conditioned medium; CM), progesterone (P4), and the combination of those biofluids (Σ) as chemotactic agents and modulators of spermatozoa fertility in vitro. A chemotaxis chamber was designed consisting of two independent wells, A and B, connected by a tube. The spermatozoa are deposited in well A, and the chemoattractants in well B. The concentrations of biofluids that attracted a higher proportion of spermatozoa to well B were 0.25% FF, 0.25% OF, 0.06% CM, 10 pM P4 and 0.25% of a combination of biofluids (Σ2), which attracted between 3.3 and 12.3% of spermatozoa (p < 0.05). The motility of spermatozoa recovered in well B was determined and the chemotactic potential when the sperm calcium channel CatSper was inhibited, which significantly reduced the % of spermatozoa attracted (p < 0.05). Regarding the in vitro fertility, the spermatozoa attracted by FF produced higher rates of penetration of oocytes and development of expanded blastocysts. In conclusion, porcine reproductive biofluids show an in vitro chemotactic effect on spermatozoa and modulate their fertilizing potential.
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Tamburrino L, Marchiani S, Muratori M, Luconi M, Baldi E. Progesterone, spermatozoa and reproduction: An updated review. Mol Cell Endocrinol 2020; 516:110952. [PMID: 32712385 DOI: 10.1016/j.mce.2020.110952] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 06/16/2020] [Accepted: 07/20/2020] [Indexed: 12/12/2022]
Abstract
The rapid effects of steroids on spermatozoa have been demonstrated for the first time more than three decades ago. Progesterone (P), which is present throughout the female genital tract with peaks of levels in the cumulus matrix surrounding the oocyte, has been shown to stimulate several sperm functions in vitro, including capacitation, hyperactivation, chemotaxis and acrosome reaction (AR). Besides an increase of intracellular calcium, P has been shown to activate other sperm signalling pathways including tyrosine phosphorylation of several sperm proteins. All these effects are mediated by extra-nuclear pathways likely involving interaction with molecules present on the sperm surface. In particular, the increase in intracellular calcium ([Ca2+]i) in spermatozoa from human and several other mammalian species is mediated by the sperm specific calcium channel CatSper, whose expression and function are required for sperm hyperactive motility. P-mediated CatSper activation is indeed involved in promoting sperm hyperactivation, but the involvement of this channel in other P-stimulated sperm functions, such as AR and chemotaxis, is less clear and further studies are required to disclose all the involved pathways. In human spermatozoa, responsiveness to P in terms of [Ca2+]i increase and AR is highly related to sperm fertilizing ability in vitro, suggesting that the steroid is a physiological inducer of AR during in vitro fertilization. In view of their physiological relevance, P-stimulated sperm functions are currently investigated to develop new tools to select highly performant spermatozoa for assisted reproduction.
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Affiliation(s)
- Lara Tamburrino
- Department of Experimental and Clinical Medicine, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy
| | - Sara Marchiani
- Department of Experimental and Clinical Medicine, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy
| | - Monica Muratori
- Department of Experimental and Clinical Biomedical Science, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy
| | - Michaela Luconi
- Department of Experimental and Clinical Biomedical Science, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy
| | - Elisabetta Baldi
- Department of Experimental and Clinical Medicine, University of Florence, Viale Pieraccini 6, 50139, Florence, Italy.
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8
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Brown SG, Publicover SJ, Barratt CLR, Martins da Silva SJ. Human sperm ion channel (dys)function: implications for fertilization. Hum Reprod Update 2020; 25:758-776. [PMID: 31665287 PMCID: PMC6847974 DOI: 10.1093/humupd/dmz032] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 07/14/2019] [Accepted: 08/13/2019] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Intensive research on sperm ion channels has identified members of several ion channel families in both mouse and human sperm. Gene knock-out studies have unequivocally demonstrated the importance of the calcium and potassium conductances in sperm for fertility. In both species, the calcium current is carried by the highly complex cation channel of sperm (CatSper). In mouse sperm, the potassium current has been conclusively shown to be carried by a channel consisting of the pore forming subunit SLO3 and auxiliary subunit leucine-rich repeat-containing 52 (LRRC52). However, in human sperm it is controversial whether the pore forming subunit of the channel is composed of SLO3 and/or SLO1. Deciphering the role of the proton-specific Hv1 channel is more challenging as it is only expressed in human sperm. However, definitive evidence for a role in, and importance for, human fertility can only be determined through studies using clinical samples. OBJECTIVE AND RATIONALE This review aims to provide insight into the role of sperm ion channels in human fertilization as evidenced from recent studies of sperm from infertile men. We also summarize the key discoveries from mouse ion channel knock-out models and contrast the properties of mouse and human CatSper and potassium currents. We detail the evidence for, and consequences of, defective ion channels in human sperm and discuss hypotheses to explain how defects arise and why affected sperm have impaired fertilization potential. SEARCH METHODS Relevant studies were identified using PubMed and were limited to ion channels that have been characterized in mouse and human sperm. Additional notable examples from other species are included as appropriate. OUTCOMES There are now well-documented fundamental differences between the properties of CatSper and potassium channel currents in mouse and human sperm. However, in both species, sperm lacking either channel cannot fertilize in vivo and CatSper-null sperm also fail to fertilize at IVF. Sperm-lacking potassium currents are capable of fertilizing at IVF, albeit at a much lower rate. However, additional complex and heterogeneous ion channel dysfunction has been reported in sperm from infertile men, the causes of which are unknown. Similarly, the nature of the functional impairment of affected patient sperm remains elusive. There are no reports of studies of Hv1 in human sperm from infertile men. WIDER IMPLICATIONS Recent studies using sperm from infertile men have given new insight and critical evidence supporting the supposition that calcium and potassium conductances are essential for human fertility. However, it should be highlighted that many fundamental questions remain regarding the nature of molecular and functional defects in sperm with dysfunctional ion channels. The development and application of advanced technologies remains a necessity to progress basic and clinical research in this area, with the aim of providing effective screening methodologies to identify and develop treatments for affected men in order to help prevent failed ART cycles. Conversely, development of drugs that block calcium and/or potassium conductances in sperm is a plausible strategy for producing sperm-specific contraceptives.
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Affiliation(s)
- Sean G Brown
- School of Applied Sciences, Abertay University, Dundee DD11HG, UK
| | | | - Christopher L R Barratt
- Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD19SY, UK
| | - Sarah J Martins da Silva
- Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD19SY, UK
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9
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Schiffer C, Rieger S, Brenker C, Young S, Hamzeh H, Wachten D, Tüttelmann F, Röpke A, Kaupp UB, Wang T, Wagner A, Krallmann C, Kliesch S, Fallnich C, Strünker T. Rotational motion and rheotaxis of human sperm do not require functional CatSper channels and transmembrane Ca 2+ signaling. EMBO J 2020; 39:e102363. [PMID: 31957048 PMCID: PMC7024840 DOI: 10.15252/embj.2019102363] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 10/30/2019] [Accepted: 12/06/2019] [Indexed: 12/23/2022] Open
Abstract
Navigation of sperm in fluid flow, called rheotaxis, provides long‐range guidance in the mammalian oviduct. The rotation of sperm around their longitudinal axis (rolling) promotes rheotaxis. Whether sperm rolling and rheotaxis require calcium (Ca2+) influx via the sperm‐specific Ca2+ channel CatSper, or rather represent passive biomechanical and hydrodynamic processes, has remained controversial. Here, we study the swimming behavior of sperm from healthy donors and from infertile patients that lack functional CatSper channels, using dark‐field microscopy, optical tweezers, and microfluidics. We demonstrate that rolling and rheotaxis persist in CatSper‐deficient human sperm. Furthermore, human sperm undergo rolling and rheotaxis even when Ca2+ influx is prevented. Finally, we show that rolling and rheotaxis also persist in mouse sperm deficient in both CatSper and flagellar Ca2+‐signaling domains. Our results strongly support the concept that passive biomechanical and hydrodynamic processes enable sperm rolling and rheotaxis, rather than calcium signaling mediated by CatSper or other mechanisms controlling transmembrane Ca2+ flux.
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Affiliation(s)
- Christian Schiffer
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Steffen Rieger
- Optical Technologies Group, Institute of Applied Physics, University of Münster, Münster, Germany
| | - Christoph Brenker
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Samuel Young
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Hussein Hamzeh
- Molecular Sensory Systems, Center of Advanced European Studies and Research, Bonn, Germany
| | - Dagmar Wachten
- Minerva Max Planck Research Group, Molecular Physiology, Center of Advanced European Studies and Research, Bonn, Germany.,Institute of Innate Immunity, University Hospital, University of Bonn, Bonn, Germany
| | - Frank Tüttelmann
- Institute of Human Genetics, University of Münster, Münster, Germany
| | - Albrecht Röpke
- Institute of Human Genetics, University of Münster, Münster, Germany
| | - U Benjamin Kaupp
- Molecular Sensory Systems, Center of Advanced European Studies and Research, Bonn, Germany
| | - Tao Wang
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany.,Institute of Life Science and School of Life Science, Nanchang University, Nanchang, China
| | - Alice Wagner
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany.,Institute of Human Genetics, University of Münster, Münster, Germany
| | - Claudia Krallmann
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Sabine Kliesch
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Carsten Fallnich
- Optical Technologies Group, Institute of Applied Physics, University of Münster, Münster, Germany.,Cells-in-Motion Cluster of Excellence (EXC1003-CiM), Münster, Germany
| | - Timo Strünker
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany.,Cells-in-Motion Cluster of Excellence (EXC1003-CiM), Münster, Germany
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10
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Chávez JC, Darszon A, Treviño CL, Nishigaki T. Quantitative Intracellular pH Determinations in Single Live Mammalian Spermatozoa Using the Ratiometric Dye SNARF-5F. Front Cell Dev Biol 2020; 7:366. [PMID: 32010689 PMCID: PMC6978660 DOI: 10.3389/fcell.2019.00366] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 12/13/2019] [Indexed: 11/13/2022] Open
Abstract
Intracellular pH (pH i ) plays a crucial role in mammalian sperm physiology. However, it is a challenging task to acquire quantitative single sperm pH i images due to their small size and beating flagella. In this study, we established a robust pH i imaging system using the dual-emission ratiometric pH indicator, SNARF-5F. Simultaneous good signal/noise ratio fluorescence signals were obtained exciting with a green high-power LED (532 nm) and acquiring with an EM-CCD camera through an image splitter with two band-pass filters (550-600 nm, channel 1; 630-650 nm, channel 2). After in vivo calibration, we established an imaging system that allows determination of absolute pH i values in spermatozoa, minimizing cell movement artifacts. Using this system, we determined that bicarbonate increases non-capacitated human pH i with slower kinetics than in mouse spermatozoa. This difference suggests that distinct ionic transporters might be involved in the bicarbonate influx into human and mouse spermatozoa. Alternatively, pH i regulation downstream bicarbonate influx into spermatozoa could be different between the two species.
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Affiliation(s)
| | | | | | - Takuya Nishigaki
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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11
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Achikanu C, Pendekanti V, Teague R, Publicover S. Effects of pH manipulation, CatSper stimulation and Ca2+-store mobilization on [Ca2+]i and behaviour of human sperm. Hum Reprod 2018; 33:1802-1811. [DOI: 10.1093/humrep/dey280] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Accepted: 08/22/2018] [Indexed: 12/27/2022] Open
Affiliation(s)
- Cosmas Achikanu
- School of Biosciences, the University of Birmingham, Birmingham, UK
| | | | - Rebecca Teague
- School of Biosciences, the University of Birmingham, Birmingham, UK
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12
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Rennhack A, Schiffer C, Brenker C, Fridman D, Nitao ET, Cheng Y, Tamburrino L, Balbach M, Stölting G, Berger TK, Kierzek M, Alvarez L, Wachten D, Zeng X, Baldi E, Publicover SJ, Benjamin Kaupp U, Strünker T. A novel cross-species inhibitor to study the function of CatSper Ca 2+ channels in sperm. Br J Pharmacol 2018; 175:3144-3161. [PMID: 29723408 PMCID: PMC6031884 DOI: 10.1111/bph.14355] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Revised: 04/14/2018] [Accepted: 04/20/2018] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND AND PURPOSE Sperm from many species share the sperm-specific Ca2+ channel CatSper that controls the intracellular Ca2+ concentration and, thereby, the swimming behaviour. A growing body of evidence suggests that the mechanisms controlling the activity of CatSper and its role during fertilization differ among species. A lack of suitable pharmacological tools has hampered the elucidation of the function of CatSper. Known inhibitors of CatSper exhibit considerable side effects and also inhibit Slo3, the principal K+ channel of mammalian sperm. The compound RU1968 was reported to suppress Ca2+ signaling in human sperm by an unknown mechanism. Here, we examined the action of RU1968 on CatSper in sperm from humans, mice, and sea urchins. EXPERIMENTAL APPROACH We resynthesized RU1968 and studied its action on sperm from humans, mice, and the sea urchin Arbacia punctulata by Ca2+ fluorimetry, single-cell Ca2+ imaging, electrophysiology, opto-chemistry, and motility analysis. KEY RESULTS RU1968 inhibited CatSper in sperm from invertebrates and mammals. The compound lacked toxic side effects in human sperm, did not affect mouse Slo3, and inhibited human Slo3 with about 15-fold lower potency than CatSper. Moreover, in human sperm, RU1968 mimicked CatSper dysfunction and suppressed motility responses evoked by progesterone, an oviductal steroid known to activate CatSper. Finally, RU1968 abolished CatSper-mediated chemotactic navigation in sea urchin sperm. CONCLUSION AND IMPLICATIONS We propose RU1968 as a novel tool to elucidate the function of CatSper channels in sperm across species.
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Affiliation(s)
- Andreas Rennhack
- Department of Molecular Sensory SystemsCenter of Advanced European Studies and Research (CAESAR)BonnGermany
| | - Christian Schiffer
- University Hospital Münster, Centre of Reproductive Medicine and AndrologyMünsterGermany
| | - Christoph Brenker
- University Hospital Münster, Centre of Reproductive Medicine and AndrologyMünsterGermany
| | - Dmitry Fridman
- Department of Molecular Sensory SystemsCenter of Advanced European Studies and Research (CAESAR)BonnGermany
| | - Elis T Nitao
- School of BiosciencesUniversity of BirminghamBirminghamUK
| | - Yi‐Min Cheng
- Institute of Life Science and School of Life ScienceNanchang UniversityNanchangJiangxiChina
| | - Lara Tamburrino
- Department of Experimental and Clinical Medicine, Center of Excellence DENOTHEUniversity of FlorenceFlorenceItaly
| | - Melanie Balbach
- Department of Molecular Sensory SystemsCenter of Advanced European Studies and Research (CAESAR)BonnGermany
| | - Gabriel Stölting
- Institute of Complex Systems – Zelluläre Biophysik 4, Forschungszentrum JülichJülichGermany
| | - Thomas K Berger
- Department of Molecular Sensory SystemsCenter of Advanced European Studies and Research (CAESAR)BonnGermany
| | - Michelina Kierzek
- University Hospital Münster, Centre of Reproductive Medicine and AndrologyMünsterGermany
| | - Luis Alvarez
- Department of Molecular Sensory SystemsCenter of Advanced European Studies and Research (CAESAR)BonnGermany
| | - Dagmar Wachten
- Max‐Planck Research Group of Molecular Physiology, Center of Advanced European Studies and ResearchBonnGermany
- Institute of Innate ImmunityUniversity Hospital, University of BonnBonnGermany
| | - Xu‐Hui Zeng
- Institute of Life Science and School of Life ScienceNanchang UniversityNanchangJiangxiChina
| | - Elisabetta Baldi
- Department of Experimental and Clinical Medicine, Center of Excellence DENOTHEUniversity of FlorenceFlorenceItaly
| | | | - U Benjamin Kaupp
- Department of Molecular Sensory SystemsCenter of Advanced European Studies and Research (CAESAR)BonnGermany
| | - Timo Strünker
- University Hospital Münster, Centre of Reproductive Medicine and AndrologyMünsterGermany
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13
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Puga Molina LC, Luque GM, Balestrini PA, Marín-Briggiler CI, Romarowski A, Buffone MG. Molecular Basis of Human Sperm Capacitation. Front Cell Dev Biol 2018; 6:72. [PMID: 30105226 PMCID: PMC6078053 DOI: 10.3389/fcell.2018.00072] [Citation(s) in RCA: 130] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Accepted: 06/19/2018] [Indexed: 12/31/2022] Open
Abstract
In the early 1950s, Austin and Chang independently described the changes that are required for the sperm to fertilize oocytes in vivo. These changes were originally grouped under name of “capacitation” and were the first step in the development of in vitro fertilization (IVF) in humans. Following these initial and fundamental findings, a remarkable number of observations led to characterization of the molecular steps behind this process. The discovery of certain sperm-specific molecules and the possibility to record ion currents through patch-clamp approaches helped to integrate the initial biochemical observation with the activity of ion channels. This is of particular importance in the male gamete due to the fact that sperm are transcriptionally inactive. Therefore, sperm must control all these changes that occur during their transit through the male and female reproductive tracts by complex signaling cascades that include post-translational modifications. This review is focused on the principal molecular mechanisms that govern human sperm capacitation with particular emphasis on comparing all the reported pieces of evidence with the mouse model.
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Affiliation(s)
- Lis C Puga Molina
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Buenos Aires, Argentina
| | - Guillermina M Luque
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Buenos Aires, Argentina
| | - Paula A Balestrini
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Buenos Aires, Argentina
| | - Clara I Marín-Briggiler
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Buenos Aires, Argentina
| | - Ana Romarowski
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Buenos Aires, Argentina
| | - Mariano G Buffone
- Instituto de Biología y Medicina Experimental, Consejo Nacional de Investigaciones Científicas y Tecnológicas, Buenos Aires, Argentina
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14
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Fafula RV, Danylo Halytsky Lviv National Medical University, Ukraine, Danylovych GV, Besedina AS, Melnyk OV, Vorobets ZD, Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv, Danylo Halytsky Lviv National Medical University, Ukraine, Danylo Halytsky Lviv National Medical University, Ukraine, Danylo Halytsky Lviv National Medical University, Ukraine. Responsiveness to progesterone and potassium channel blockers 4-aminopyridine, tetraethylammonium and free Ca(2+) contentration in spermatozoa of patients with oligozoospermia/leucocytospermia. Ukr Biochem J 2018; 90:48-57. [DOI: 10.15407/ubj90.01.048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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15
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Da Costa R, Botana D, Piñero S, Proverbio F, Marín R. Cadmium inhibits motility, activities of plasma membrane Ca2+-ATPase and axonemal dynein-ATPase of human spermatozoa. Andrologia 2015; 48:464-9. [DOI: 10.1111/and.12466] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2015] [Indexed: 11/30/2022] Open
Affiliation(s)
- R. Da Costa
- Laboratorio de Bioenergética Celular; Centro de Biofísica y Bioquímica (CBB); Instituto Venezolano de Investigaciones Científicas (IVIC); Caracas Venezuela
| | - D. Botana
- Laboratorio de Bioenergética Celular; Centro de Biofísica y Bioquímica (CBB); Instituto Venezolano de Investigaciones Científicas (IVIC); Caracas Venezuela
| | - S. Piñero
- Laboratorio de Bioenergética Celular; Centro de Biofísica y Bioquímica (CBB); Instituto Venezolano de Investigaciones Científicas (IVIC); Caracas Venezuela
| | - F. Proverbio
- Laboratorio de Bioenergética Celular; Centro de Biofísica y Bioquímica (CBB); Instituto Venezolano de Investigaciones Científicas (IVIC); Caracas Venezuela
| | - R. Marín
- Laboratorio de Bioenergética Celular; Centro de Biofísica y Bioquímica (CBB); Instituto Venezolano de Investigaciones Científicas (IVIC); Caracas Venezuela
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16
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Morris J, Jones S, Howl J, Lukanowska M, Lefievre L, Publicover S. Cell-penetrating peptides, targeting the regulation of store-operated channels, slow decay of the progesterone-induced [Ca2+]i signal in human sperm. Mol Hum Reprod 2015; 21:563-70. [PMID: 25882543 PMCID: PMC4487447 DOI: 10.1093/molehr/gav019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Revised: 04/02/2015] [Accepted: 04/09/2015] [Indexed: 01/08/2023] Open
Abstract
Previous work has provided evidence for involvement of store-operated channels (SOCs) in [Ca(2+)]i signalling of human sperm, including a contribution to the transient [Ca(2+)]i elevation that occurs upon activation of CatSper, a sperm-specific cation channel localized to the flagellum, by progesterone. To further investigate the potential involvement of SOCs in the generation of [Ca(2+)]i signals in human sperm, we have used cell-penetrating peptides containing the important basic sequence KIKKK, part of the STIM-Orai activating region/CRAC activating domain (SOAR/CAD) of the regulatory protein stromal interaction molecule 1. SOAR/CAD plays a key role in controlling the opening of SOCs, which occurs upon mobilization of stored Ca(2+). Resting [Ca(2+)]i temporarily decreased upon application of KIKKK peptide (3-4 min), but scrambled KIKKK peptide had a similar effect, indicating that this action was not sequence-specific. However, in cells pretreated with KIKKK, the transient [Ca(2+)]i elevation induced by stimulation with progesterone decayed significantly more slowly than in parallel controls and in cells pretreated with scrambled KIKKK peptide. Examination of single-cell responses showed that this effect was due, at least in part, to an increase in the proportion of cells in which the initial transient was maintained for an extended period, lasting up to 10 min in a subpopulation of cells. We hypothesize that SOCs contribute to the progesterone-induced [Ca(2+)]i transient, and that interference with the regulatory mechanisms of SOC delays their closure, causing a prolongation of the [Ca(2+)]i transient.
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Affiliation(s)
- Jennifer Morris
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Sarah Jones
- Molecular Pharmacology Research Group, Research Institute in Healthcare Science, University of Wolverhampton, Wolverhampton WV1 1LY, UK
| | - John Howl
- Molecular Pharmacology Research Group, Research Institute in Healthcare Science, University of Wolverhampton, Wolverhampton WV1 1LY, UK
| | - Monika Lukanowska
- Molecular Pharmacology Research Group, Research Institute in Healthcare Science, University of Wolverhampton, Wolverhampton WV1 1LY, UK
| | - Linda Lefievre
- The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Stephen Publicover
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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17
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Abstract
The acrosome reaction is a unique event in the lifespan of sperm characterized by the exocytosis of the acrosomal content and the release of hybrid vesicles formed by patches of the outer acrosomal membrane and the plasma membrane. This unique regulated exocytosis is mediated by essentially the same membrane fusion machinery present in neuroendocrine cells. However, whereas secretion in neuroendocrine cells occurs in less than a second, the acrosome reaction is normally assessed after several minutes of incubation with inducers. In this report, we measured the kinetics of human sperm exocytosis triggered by two stimuli (calcium ionophore and progesterone) by using electron microscopy and three different approaches based on the incorporation of fluorescent Pisum sativum agglutinin into the acrosome upon opening of fusion pores connecting the extracellular medium with the acrosomal lumen. The results with the different methods are consistent with a slow kinetics (t½ = 14 min). We also manipulated the system to measure different steps of the process. We observed that cytosolic calcium increased with a relatively fast kinetics (t½ = 0.1 min). In contrast, the swelling of the acrosomal granule that precedes exocytosis was a slow process (t½ = 13 min). When swelling was completed, the fusion pore opening was fast (t½ = 0.2 min). The results indicate that acrosomal swelling is the slowest step and it determines the kinetics of the acrosome reaction. After the swelling is completed, the efflux of calcium from intracellular stores triggers fusion pores opening and the release of hybrid vesicles in seconds.
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Affiliation(s)
- C M Sosa
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina
| | - M A Pavarotti
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina
| | - M N Zanetti
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina Present address: Department of Cell Biology, Yale University School of Medicine, New Haven, CT, USA
| | - F C M Zoppino
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina Present address: Laboratory of Oncology, Institute of Experimental Medicine and Biology of Cuyo (IMBECU - CONICET), 5500 Mendoza, Argentina
| | - G A De Blas
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina
| | - L S Mayorga
- IHEM (CONICET-UNCuyo), School of Medicine, National University of Cuyo, 5500 Mendoza, Argentina
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18
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Li LF, Xiang C, Zhu YB, Qin KR. Modeling of progesterone-induced intracellular calcium signaling in human spermatozoa. J Theor Biol 2014; 351:58-66. [PMID: 24594372 DOI: 10.1016/j.jtbi.2014.02.026] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 01/23/2014] [Accepted: 02/22/2014] [Indexed: 12/11/2022]
Abstract
Calcium ion is a secondary messenger of mammalian spermatozoa. The dynamic change of its concentration plays a vital role in the process of sperm motility, capacitation, acrosome and fertilization. Progesterone released by the cumulus cells, as a potent stimulator of fertilization, can activate the calcium channels on the plasma membrane, which in turn triggers the dynamic change of intracellular calcium concentration. In this paper, a mathematical model of calcium dynamic response in mammalian spermatozoa induced by progesterone is proposed and numerical simulation of the dynamic model is conducted. The results show that the dynamic response of calcium concentration predicted by the model is in accordance with experimental evidence. The proposed dynamic model can be used to explain the phenomena observed in the experiments and predict new phenomena to be revealed by experimental investigations, which will provide the basis to quantitatively investigate the fluid mechanics and biochemistry for the sperm motility induced by progesterone.
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Affiliation(s)
- Long-Fei Li
- Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, No. 2, Linggong Rd., Dalian 116023, China
| | - Cheng Xiang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Ya-Bing Zhu
- Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, No. 2, Linggong Rd., Dalian 116023, China
| | - Kai-Rong Qin
- Faculty of Electronic Information and Electrical Engineering, Dalian University of Technology, No. 2, Linggong Rd., Dalian 116023, China.
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Sinding C, Kemper E, Spornraft-ragaller P, Hummel T. Decreased Perception of Bourgeonal May Be Linked to Male Idiopathic Infertility. Chem Senses 2013; 38:439-45. [DOI: 10.1093/chemse/bjt009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
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20
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Lefièvre L, Nash K, Mansell S, Costello S, Punt E, Correia J, Morris J, Kirkman-Brown J, Wilson SM, Barratt CL, Publicover S. 2-APB-potentiated channels amplify CatSper-induced Ca(2+) signals in human sperm. Biochem J 2012; 448:189-200. [PMID: 22943284 DOI: 10.1042/BJ20120339] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Ca2+i signalling is pivotal to sperm function. Progesterone, the best-characterized agonist of human sperm Ca2+i signalling, stimulates a biphasic [Ca2+]i rise, comprising a transient and subsequent sustained phase. In accordance with recent reports that progesterone directly activates CatSper, the [Ca2+]i transient was detectable in the anterior flagellum (where CatSper is expressed) 1–2 s before responses in the head and neck. Pre-treatment with 5 μM 2-APB (2-aminoethoxydiphenyl borate), which enhances activity of store-operated channel proteins (Orai) by facilitating interaction with their activator [STIM (stromal interaction molecule)] ‘amplified’ progesterone-induced [Ca2+]i transients at the sperm neck/midpiece without modifying kinetics. The flagellar [Ca2+]i response was unchanged. 2-APB (5 μM) also enhanced the sustained response in the midpiece, possibly reflecting mitochondrial Ca2+ accumulation downstream of the potentiated [Ca2+]i transient. Pre-treatment with 50–100 μM 2-APB failed to potentiate the transient and suppressed sustained [Ca2+]i elevation. When applied during the [Ca2+]i plateau, 50–100 μM 2-APB caused a transient fall in [Ca2+]i, which then recovered despite the continued presence of 2-APB. Loperamide (a chemically different store-operated channel agonist) enhanced the progesterone-induced [Ca2+]i signal and potentiated progesterone-induced hyperactivated motility. Neither 2-APB nor loperamide raised pHi (which would activate CatSper) and both compounds inhibited CatSper currents. STIM and Orai were detected and localized primarily to the neck/midpiece and acrosome where Ca2+ stores are present and the effects of 2-APB are focussed, but store-operated currents could not be detected in human sperm. We propose that 2-APB-sensitive channels amplify [Ca2+]i elevation induced by progesterone (and other CatSper agonists), amplifying, propagating and providing spatio-temporal complexity in [Ca2+]i signals of human sperm.
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21
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Servin-Vences MR, Tatsu Y, Ando H, Guerrero A, Yumoto N, Darszon A, Nishigaki T. A caged progesterone analog alters intracellular Ca2+ and flagellar bending in human sperm. Reproduction 2012; 144:101-9. [PMID: 22580372 DOI: 10.1530/rep-11-0268] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Progesterone is a physiological agonist for mammalian sperm, modulating its flagellar movement and facilitating the acrosome reaction. To study the initial action of progesterone, we developed a caged analog with a photosensitive group: nitrophenylethanediol, at position 20. Using this compound combined with stroboscopic illumination, we performed Ca(2)(+) imaging of human spermatozoa and analyzed the effects of progesterone on the intracellular Ca(2)(+) concentration ([Ca(2)(+)](i)) of beating flagella for the first time. We observed a transient [Ca(2)(+)](i) increase in the head and the flagellum upon photolysis of the caged progesterone and an increase in flagellar curvature. Detailed kinetic analysis revealed that progesterone elicits an increase in the [Ca(2)(+)](i) immediately in the flagellum (mid-piece and principal piece), thereafter in the head with a short time lag. This observation is different from the progesterone-induced Ca(2)(+) mobilization in mouse spermatozoa, where the Ca(2)(+) rise initiates at the base of the sperm head. Our finding is mostly consistent with the recent discovery that progesterone activates CatSper channels in human spermatozoa, but not in mouse spermatozoa.
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Affiliation(s)
- M Rocio Servin-Vences
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Apdo Postal 510-3, Cuernavaca, Morelos 62250, Mexico
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Brenker C, Goodwin N, Weyand I, Kashikar ND, Naruse M, Krähling M, Müller A, Kaupp UB, Strünker T. The CatSper channel: a polymodal chemosensor in human sperm. EMBO J 2012; 31:1654-65. [PMID: 22354039 DOI: 10.1038/emboj.2012.30] [Citation(s) in RCA: 170] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Accepted: 01/18/2012] [Indexed: 01/10/2023] Open
Abstract
The sperm-specific CatSper channel controls the intracellular Ca(2+) concentration ([Ca(2+)](i)) and, thereby, the swimming behaviour of sperm. In humans, CatSper is directly activated by progesterone and prostaglandins-female factors that stimulate Ca(2+) influx. Other factors including neurotransmitters, chemokines, and odorants also affect sperm function by changing [Ca(2+)](i). Several ligands, notably odorants, have been proposed to control Ca(2+) entry and motility via G protein-coupled receptors (GPCRs) and cAMP-signalling pathways. Here, we show that odorants directly activate CatSper without involving GPCRs and cAMP. Moreover, membrane-permeable analogues of cyclic nucleotides that have been frequently used to study cAMP-mediated Ca(2+) signalling also activate CatSper directly via an extracellular site. Thus, CatSper or associated protein(s) harbour promiscuous binding sites that can host various ligands. These results contest current concepts of Ca(2+) signalling by GPCR and cAMP in mammalian sperm: ligands thought to activate metabotropic pathways, in fact, act via a common ionotropic mechanism. We propose that the CatSper channel complex serves as a polymodal sensor for multiple chemical cues that assist sperm during their voyage across the female genital tract.
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Baldi E, Luconi M, Krausz C, Forti G. Editorial commentary: Progesterone and spermatozoa: a long-lasting liaison comes to definition. Hum Reprod 2011; 26:2933-4. [DOI: 10.1093/humrep/der289] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
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24
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Park KH, Kim BJ, Kang J, Nam TS, Lim JM, Kim HT, Park JK, Kim YG, Chae SW, Kim UH. Ca2+ signaling tools acquired from prostasomes are required for progesterone-induced sperm motility. Sci Signal 2011; 4:ra31. [PMID: 21586728 DOI: 10.1126/scisignal.2001595] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Progesterone-induced calcium ion (Ca2+) signals in the neck region of sperm play a pivotal role in promoting sperm motility. Here, we show that a long-lasting Ca2+ signal required for sperm motility in response to progesterone depends on their pH-dependent fusion with prostasomes, which are small vesicles secreted by the prostate. We found that prostasome fusion led to the transfer of progesterone receptors, cyclic adenosine diphosphoribose (cADPR)-synthesizing enzymes, ryanodine receptors (RyRs), and other Ca2+ signaling tools from prostasomes to the sperm neck. Progesterone-induced sperm motility relied on cADPR-mediated Ca2+ mobilization through RyR located on acidic Ca2+ stores, followed by Ca2+ entry through store-operated channels. Treatment of prostasome-fused sperm with a cADPR antagonist or fusion with prostasomes in which type 2 RyR was depleted resulted in low fertilization rates, reduced sperm motility, or both. Thus, we conclude that sperm motility depends on the acquisition of Ca2+ signaling tools from prostasomes.
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Affiliation(s)
- Kwang-Hyun Park
- Department of Biochemistry, Chonbuk National University Medical School, Jeonju 561-180, Korea
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Strünker T, Goodwin N, Brenker C, Kashikar ND, Weyand I, Seifert R, Kaupp UB. The CatSper channel mediates progesterone-induced Ca2+ influx in human sperm. Nature 2011; 471:382-6. [PMID: 21412338 DOI: 10.1038/nature09769] [Citation(s) in RCA: 389] [Impact Index Per Article: 29.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 12/17/2010] [Indexed: 12/20/2022]
Abstract
In the oviduct, cumulus cells that surround the oocyte release progesterone. In human sperm, progesterone stimulates a Ca(2+) increase by a non-genomic mechanism. The Ca(2+) signal has been proposed to control chemotaxis, hyperactivation and acrosomal exocytosis of sperm. However, the underlying signalling mechanism has remained mysterious. Here we show that progesterone activates the sperm-specific, pH-sensitive CatSper Ca(2+) channel. We found that both progesterone and alkaline pH stimulate a rapid Ca(2+) influx with almost no latency, incompatible with a signalling pathway involving metabotropic receptors and second messengers. The Ca(2+) signals evoked by alkaline pH and progesterone are inhibited by the Ca(v) channel blockers NNC 55-0396 and mibefradil. Patch-clamp recordings from sperm reveal an alkaline-activated current carried by mono- and divalent ions that exhibits all the hallmarks of sperm-specific CatSper Ca(2+) channels. Progesterone substantially enhances the CatSper current. The alkaline- and progesterone-activated CatSper current is inhibited by both drugs. Our results resolve a long-standing controversy over the non-genomic progesterone signalling. In human sperm, either the CatSper channel itself or an associated protein serves as the non-genomic progesterone receptor. The identification of CatSper channel blockers will greatly facilitate the study of Ca(2+) signalling in sperm and help to define further the physiological role of progesterone and CatSper.
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Affiliation(s)
- Timo Strünker
- Center of Advanced European Studies and Research, Abteilung Molekulare Neurosensorik, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
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26
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Matás C, Sansegundo M, Ruiz S, García-vázquez F, Gadea J, Romar R, Coy P. Sperm treatment affects capacitation parameters and penetration ability of ejaculated and epididymal boar spermatozoa. Theriogenology 2010; 74:1327-40. [DOI: 10.1016/j.theriogenology.2010.06.002] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/02/2010] [Accepted: 06/02/2010] [Indexed: 11/20/2022]
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Arienti G, Mazzoni M, Spapperi C, Saccardi C, Palmerini CA. Effect of FSH and progesterone on human spermatozoa cytosolic calcium. J Steroid Biochem Mol Biol 2010; 120:180-3. [PMID: 20417711 DOI: 10.1016/j.jsbmb.2010.04.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 04/14/2010] [Accepted: 04/15/2010] [Indexed: 11/30/2022]
Abstract
Ejaculated spermatozoa must undergo a number of modifications before fertilizing the oocyte: among these the capacitation and the acrosome reaction. Calcium signals play an essential role in these functional and structural modifications. Mature spermatozoa have few organelles and a very small cytoplasmic volume but maintain the homeostasis of [Ca(2+)](c) with great accuracy. We study Ca(2+) mobilization in human spermatozoa exposed to FSH and progesterone by measuring the [Ca(2+)](c) with the FURA-2AM method and report for the first time that the exposure to FSH (up to 98ng/ml) produced an increase of [Ca(2+)](c) to an extent comparable to that observed with 1muM progesterone. FSH and progesterone increase the spermatozoa [Ca(2+)](c) by acting primarily on calcium entry from the external medium. The effects of the two hormones on [Ca(2+)](c) were similar but not identical; the pre-treatment of progesterone blocks the effects of FSH, but not vice-versa. The increase of [Ca(2+)](c) due to FSH was more sensitive to nifedipine (VOCCs inhibitor) than that of progesterone. The effects of these hormones on calcium homeostasis may be relevant for sperm activation.
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Affiliation(s)
- Giuseppe Arienti
- Laboratory of Biochemistry, Department of Internal Medicine, Via del Giochetto, 06127 Perugia, Italy
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28
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Sainath SB, Reddy PS. Melatonergic regulation of hemolymph sugar levels in the freshwater edible crab, Oziotelphusa senex senex. ACTA ACUST UNITED AC 2010; 313:201-8. [PMID: 20140952 DOI: 10.1002/jez.594] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In this study, the hyperglycemic effect of melatonin in the freshwater edible crab, Oziotelphusa senex senex, is investigated. Injection of melatonin induced hyperglycemia in a dose-dependent manner. Administration of melatonin produced hyperglycemia in both intact and eyestalk-ablated crabs. Bilateral eyestalk ablation resulted in significant increase in the total carbohydrates and glycogen levels with a significant decrease in phosphorylase activity in the hepatopancreas and muscle of the crabs. Injection of melatonin resulted in significant decrease in the total carbohydrate and glycogen levels, with an increase in phosphorylase activity in hepatopancreas and muscle of both intact and eyestalk-ablated crabs. From the results, it is hypothesized that melatonin-induced hyperglycemia in the crab, O. senex senex, is not mediated by eyestalk hyperglycemic hormone.
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Affiliation(s)
- S B Sainath
- Department of Biotechnology, Sri Venkateswara University, Tirupati, Andhra pradesh, India
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Baldi E, Luconi M, Muratori M, Marchiani S, Tamburrino L, Forti G. Nongenomic activation of spermatozoa by steroid hormones: facts and fictions. Mol Cell Endocrinol 2009; 308:39-46. [PMID: 19549590 DOI: 10.1016/j.mce.2009.02.006] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2008] [Revised: 01/30/2009] [Accepted: 02/17/2009] [Indexed: 12/26/2022]
Abstract
The rapid effects of steroids on spermatozoa have been demonstrated for the first time two decades ago. Progesterone (P), which is present throughout the female genital tract with peaks of levels in the cumulus matrix surrounding the oocyte, stimulates several sperm functions, including hyperactivation and acrosome reaction. These effects are mediated by an extranuclear pathway, as P stimulates an influx of calcium, the tyrosine phosphorylation of sperm proteins and other signalling cascades in a rapid manner. Whether these effects are receptor mediated and which receptors mediate these effects are still a matter of discussion despite all the efforts of the scientific community aimed at identifying them during the last 20 years. Although responsiveness to P is related to sperm fertilizing ability, the physiological role of P during the process of fertilization is discussed, and recent evidence points for a role of the steroid as a chemotactic agent for sperm. A similar situation applies for estrogens (E), which have been shown to induce direct effects on sperm by an extranuclear pathway. In particular, E appear to decrease acrosome reaction in response to P, exerting a role in ensuring an appropriate timing for sperm exocytosis during the process of fertilization.
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Affiliation(s)
- Elisabetta Baldi
- Dept. of Clinical Physiopathology, Andrology Unit, Center of Excellence for Research, Transfer and High Education DeNothe, University of Florence, Italy.
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Brewis IA, Van Gestel RA, Gadella BM, Jones R, Publicover SJ, Roldan ERS, Frayne J, Barratt CLR. The spermatozoon at fertilisation: Current understanding and future research directions. HUM FERTIL 2009; 8:241-51. [PMID: 16393824 DOI: 10.1080/14647270500420160] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Ian A Brewis
- Biostatistics and Bioinformatics Unit & Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff, UK.
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Espino J, Mediero M, Lozano GM, Bejarano I, Ortiz Á, García JF, Pariente JA, Rodríguez AB. Reduced levels of intracellular calcium releasing in spermatozoa from asthenozoospermic patients. Reprod Biol Endocrinol 2009; 7:11. [PMID: 19200382 PMCID: PMC2645411 DOI: 10.1186/1477-7827-7-11] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2008] [Accepted: 02/06/2009] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Asthenozoospermia is one of the most common findings present in infertile males characterized by reduced or absent sperm motility, but its aetiology remains unknown in most cases. In addition, calcium is one of the most important ions regulating sperm motility. In this study we have investigated the progesterone-evoked intracellular calcium signal in ejaculated spermatozoa from men with normospermia or asthenozoospermia. METHODS Human ejaculates were obtained from healthy volunteers and asthenospermic men by masturbation after 4-5 days of abstinence. For determination of cytosolic free calcium concentration, spermatozoa were loaded with the fluorescent ratiometric calcium indicator Fura-2. RESULTS Treatment of spermatozoa from normospermic men with 20 micromolar progesterone plus 1 micromolar thapsigargin in a calcium free medium induced a typical transient increase in cytosolic free calcium concentration due to calcium release from internal stores. Similar results were obtained when spermatozoa were stimulated with progesterone alone. Subsequent addition of calcium to the external medium evoked a sustained elevation in cytosolic free calcium concentration indicative of capacitative calcium entry. However, when progesterone plus thapsigargin were administered to spermatozoa from patients with asthenozoospermia, calcium signal and subsequent calcium entry was much smaller compared to normospermic patients. As expected, pretreatment of normospermic spermatozoa with both the anti-progesterone receptor c262 antibody and with progesterone receptor antagonist RU-38486 decreased the calcium release induced by progesterone. Treatment of spermatozoa with cytochalasin D or jasplakinolide decreased the calcium entry evoked by depletion of internal calcium stores in normospermic patients, whereas these treatments proved to be ineffective at modifying the calcium entry in patients with asthenozoospermia. CONCLUSION Our results suggest that spermatozoa from asthenozoospermic patients present a reduced responsiveness to progesterone.
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Affiliation(s)
- Javier Espino
- Department of Physiology, Faculty of Science, University of Extremadura, Badajoz, Spain
| | - Matías Mediero
- Department of Physiology, Faculty of Science, University of Extremadura, Badajoz, Spain
| | | | - Ignacio Bejarano
- Department of Physiology, Faculty of Science, University of Extremadura, Badajoz, Spain
| | - Águeda Ortiz
- Extremadura Center of Human Assisted Reproduction, Badajoz, Spain
| | - Juan F García
- Extremadura Center of Human Assisted Reproduction, Badajoz, Spain
| | - José A Pariente
- Department of Physiology, Faculty of Science, University of Extremadura, Badajoz, Spain
| | - Ana B Rodríguez
- Department of Physiology, Faculty of Science, University of Extremadura, Badajoz, Spain
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Abstract
An essential step in mammalian fertilisation is the sperm acrosome reaction (AR) – exocytosis of a single large vesicle (the acrosome) that surrounds the nucleus at the apical sperm head. The acrosomal and plasma membranes fuse, resulting in both the release of factors that might facilitate penetration of the zona pellucida (which invests the egg) and the externalisation of membrane components required for gamete fusion. Exocytosis in somatic cells is a rapid process – typically complete within milliseconds – yet acrosomal enzymes are required throughout zona penetration – a period of minutes. Here, we present the first studies of this crucial and complex event occurring in real-time in individual live sperm using time-lapse fluorescence microscopy. Simultaneous imaging of separate probes for acrosomal content and inner acrosomal membrane show that rapid membrane fusion, initiated at the cell apex, is followed by exceptionally slow dispersal of acrosomal content (up to 12 minutes). Cells that lose their acrosome prematurely (spontaneous AR), compromising their ability to penetrate the egg vestments, are those that are already subject to a loss of motility and viability. Cells undergoing stimulus-induced AR (progesterone or A23187) remain viable, with a proportion remaining motile (progesterone). These findings suggest that the AR is a highly adapted form of exocytosis.
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Affiliation(s)
- Claire V. Harper
- Centre for Cell Imaging, School of Biological Sciences, Biosciences Building, Crown Street, University of Liverpool, L69 7ZB, UK
| | - Joanne A. Cummerson
- Division of Immunology, School of Infection and Host Defence, Duncan Building, Daulby Street, University of Liverpool, L69 3GA, UK
| | - Michael R. H. White
- Centre for Cell Imaging, School of Biological Sciences, Biosciences Building, Crown Street, University of Liverpool, L69 7ZB, UK
| | | | - Peter M. Johnson
- Division of Immunology, School of Infection and Host Defence, Duncan Building, Daulby Street, University of Liverpool, L69 3GA, UK
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Affiliation(s)
- U. Benjamin Kaupp
- Forschungszentrum Jülich, Institut für Neurowissenschaften und Biophysik 1, D-52425 Jülich, Germany;
| | - Nachiket D. Kashikar
- Forschungszentrum Jülich, Institut für Neurowissenschaften und Biophysik 1, D-52425 Jülich, Germany;
| | - Ingo Weyand
- Forschungszentrum Jülich, Institut für Neurowissenschaften und Biophysik 1, D-52425 Jülich, Germany;
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Bedu-Addo K, Barratt CLR, Kirkman-Brown JC, Publicover SJ. Patterns of [Ca2+]i mobilization and cell response in human spermatozoa exposed to progesterone. Dev Biol 2007; 302:324-32. [PMID: 17054937 DOI: 10.1016/j.ydbio.2006.09.040] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2006] [Revised: 09/12/2006] [Accepted: 09/21/2006] [Indexed: 11/17/2022]
Abstract
Human spermatozoa stimulated with progesterone (a product of the cumulus and thus encountered by sperm prior to fertilization in vivo) apparently mobilize Ca(2+) and respond very differently according to the way in which the steroid is presented. A progesterone concentration ramp (0-3 microM) induces [Ca(2+)](i) oscillations (repetitive store mobilization) which modify flagellar beating, whereas bolus application of micromolar progesterone causes a single large transient (causing acrosome reaction) which is apparently dependent upon Ca(2+) influx. We have investigated Ca(2+)-mobilization and functional responses in human sperm exposed to 3 muM progesterone. The [Ca(2+)](i) response to progesterone was abolished by 4 min incubation in 0 Ca(2+) medium (2 mM EGTA) but in nominally Ca(2+)-free medium (no added Ca(2+); 0 EGTA) a smaller, slow response occurred. Single cell imaging showed a similar effect of nominally Ca(2+)-free medium and approximately 5% of cells generated a small transient even in the presence of EGTA. When cells were exposed to EGTA-containing saline (5 min) and then returned to nominally Ca(2+)-free medium before stimulation, the [Ca(2+)](i) transient was greatly delayed (approximately 50 s) and rise time was doubled in comparison to cells not subjected to EGTA pre-treatment. We conclude that mobilization of stored Ca(2+) contributes a 'slow' component to the progesterone-induced [Ca(2+)](i) transient and that incubation in EGTA-buffered saline is able rapidly to deplete this store. Analysis of flagellar activity induced by 3 muM progesterone showed an effect (modified beating) associated with the [Ca(2+)](i) transient, in >80% of cells bathed in nominally Ca(2+)-free medium. This was reduced greatly in cells subjected to 5 min EGTA pre-treatment. The store-mediated transient showed a pharmacological sensitivity similar to that of progesterone-induced [Ca(2+)](i) oscillations (consistent with filling of the store by an SPCA) suggesting that the transient induced by micromolar progesterone is a 'single shot' activation of the same store that generates Ca(2+) oscillations.
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Affiliation(s)
- K Bedu-Addo
- School of Biosciences, University of Birmingham, Birmingham, UK
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35
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Harper CV, Barratt CLR, Publicover SJ, Kirkman-Brown JC. Kinetics of the progesterone-induced acrosome reaction and its relation to intracellular calcium responses in individual human spermatozoa. Biol Reprod 2006; 75:933-9. [PMID: 16957023 DOI: 10.1095/biolreprod.106.054627] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Progesterone at 3 microM triggers a biphasic (transient and sustained) increase in intracellular calcium ([Ca(2+)](i)) in human sperm, which is believed to be a prerequisite for progesterone-induced acrosome reaction (AR). As very little is known about how AR occurrence, latency, and completion relate to the characteristics of the progesterone-induced [Ca(2+)](i) signal, we examined these events using fluorescence microscopy of individual living human sperm. Direct assessment of acrosomal status after calcium imaging showed no differences in kinetics or amplitude of the preceding progesterone-induced calcium responses in acrosome-reacted and acrosome-intact cells, which indicates that the amplitude of the [Ca(2+)](i) signal is not the critical determinant of AR. Chelation of extracellular calcium to arrest AR at varying times after progesterone stimulation revealed that maximal AR occurred immediately following progesterone stimulation, during the initial transient calcium influx rather than during the sustained calcium response. Attempts to follow acrosomal dispersal in real-time by staining with the acidic organelle probes LysoTracker DND-99 and dapoxyl (2-aminoethyl) sulphonamide (DAES) proved inconclusive due to heterogeneous labeling of the cell population. Surprisingly, the dye was often not confined to the acrosome but stained the whole sperm head, which suggests that only a subpopulation of human sperm cells contains a sufficiently acidic acrosome.
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Affiliation(s)
- Claire V Harper
- School of Biosciences, The Medical School, University of Birmingham, Birmingham B15 2TT, United Kingdom.
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36
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Abstract
Sperm nicotinic acetylcholine receptors (nAChRs) can influence motility and the initiation of acrosome reaction (AR). We report that AR initiation by acetylcholine (ACh) in capacitated human sperm requires both Na+ and Ca2+ in the external medium. Pre-incubation with 50 microM 3-quinuclidinyl benzilate (QNB) or 50 nM strychnine failed to inhibit the ACh-initiated AR, demonstrating that muscarinic AChRs and nAChRs containing alpha9 subunits do not mediate this event. Choline (2.5, 5 and 10 mM), a highly specific but low potency agonist of the alpha7 nAChR initiated AR, with its effect blocked by the nAChR antagonist methyllycaconitine (MLA). ACh (50-400 microM) stimulated a small transient rise in the intracellular Ca2+ in sperm populations loaded with FURA-2, with 200 microM ACh being maximal (146 nM +/- 23 SEM). The nAChR antagonists, alpha-bungarotoxin (alpha-BTX) and MLA, reduced the ACh-initiated Ca2+ rise by 75 and 78%, respectively, demonstrating the majority of the rise is mediated through nAChRs containing alpha7 or alpha9 subunits. Single cell imaging studies using FLUO-3 resolved two patterns of ACh-stimulated Ca2+ increase in the sperm head: 94% of responding sperm displayed a rise (59.6% +/- 5.7 SEM increase from resting fluorescence intensity), returning to resting levels over a period of 2-3 min. The remaining sperm (6%) displayed a sharp spike of Ca2+ ( approximately 1 min; 86% +/- 4.3 SEM change in fluorescence intensity), followed by abrupt loss of fluorescence, a pattern suggestive of AR. A Ca2+ influx in the sperm midpiece appeared to accompany the Ca2+ influx seen in the head. These observations confirm an ionotropic role for nAChRs in sperm function.
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Affiliation(s)
- C Bray
- Department of Cell Biology and Human Anatomy, School of Medicine, University of California at Davis, One Shields Avenue, Davis, CA, USA.
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Jimenez-Gonzalez C, Michelangeli F, Harper CV, Barratt CLR, Publicover SJ. Calcium signalling in human spermatozoa: a specialized 'toolkit' of channels, transporters and stores. Hum Reprod Update 2005; 12:253-67. [PMID: 16338990 DOI: 10.1093/humupd/dmi050] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Ca(2+) is a ubiquitous intracellular messenger which encodes information by temporal and spatial patterns of concentration. In spermatozoa, several key functions, including acrosome reaction and motility, are regulated by cytoplasmic Ca(2+) concentration. Despite the very small size and apparent structural simplicity of spermatozoa, evidence is accumulating that they possess sophisticated mechanisms for regulation of cytoplasmic Ca(2+) concentration and generation of complex Ca(2+) signals. In this review, we consider the various components of the Ca(2+)-signalling 'toolkit' that have been characterized in somatic cells and summarize the evidence for their presence and activity in spermatozoa. In particular, data accumulated over the last few years show that spermatozoa possess one (and probably two) Ca(2+) stores as well as a range of plasma membrane pumps and channels. Selective regulation of the various components of the 'toolkit' by agonists probably allows spermatozoa to generate localized Ca(2+) signals despite their very small cytoplasmic volume, permitting the discrete and selective activation of cell functions.
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38
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Bedu-Addo K, Lefièvre L, Moseley FLC, Barratt CLR, Publicover SJ. Bicarbonate and bovine serum albumin reversibly ‘switch’ capacitation-induced events in human spermatozoa. ACTA ACUST UNITED AC 2005; 11:683-91. [PMID: 16192296 DOI: 10.1093/molehr/gah226] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
We have investigated the reversibility of biochemical and physiological changes that occur upon suspension of ejaculated human spermatozoa during in vitro capacitation. Cells were swum up in a simple HEPES-based saline [lacking bicarbonate and bovine serum albumin (BSA)], then resuspended either in supplemented Earle's balanced salt solution (sEBSS) (25 mM bicarbonate) with 0.3% BSA (for in vitro capacitation) or in medium-lacking bicarbonate and/or BSA. Progesterone-induced acrosome reaction (AR) developed during in vitro capacitation (6 h). A progesterone-induced [Ca2+]i signal was detectable in cells maintained in the simple HEPES-based saline, but upon transfer to sEBSS, the response increased three- to four-fold, saturating within <30 min. Serine/threonine phosphorylation saturated within minutes of resuspension, but tyrosine phosphorylation developed over 3 h. Return of cells to non-capacitating conditions caused reversal of all capacitation-dependent changes. The [Ca2+]i signal reverted to its 'uncapacitated' size within <30 min. Protein phosphorylation reversed gradually and could be reinduced (kinetics resembling the first response) upon resuspension in sEBSS. The ability of cells to undergo progesterone-induced AR fell to levels similar to those in uncapacitated cells within 1 h of resuspension in medium not supporting capacitation. Loss of protein phosphorylation occurred only in the absence of both bicarbonate and BSA, but effects on [Ca2+]i signalling and AR could be seen after removal of only one of these factors. We conclude that key events in the capacitation of human spermatozoa are both reversible and repeatable.
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Affiliation(s)
- K Bedu-Addo
- School of Biosciences, The Medical School, University of Birmingham, UK
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39
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Abstract
Progesterone is present at micromolar concentrations in the vicinity of the oocyte. Human spermatozoa generate a biphasic rise in intracellular calcium concentration ([Ca(2+)](i)) and undergo the acrosome reaction upon progesterone stimulation, suggesting that the hormone acts as a secondary inducer or 'primer' of the acrosome reaction in association with the zona pellucida. However, the sensitivity of human spermatozoa to progesterone is such that many cells may undergo the acrosome reaction prematurely, compromising their ability to fertilize. We have shown that exposing human spermatozoa to a progesterone gradient, simulating the stimulus encountered as sperm approach the oocyte, results in a novel response. A slow rise in [Ca(2+)](i) occurs, upon which, in many cells, [Ca(2+)](i) oscillations are superimposed. Cells showing this pattern of response do not undergo the acrosome reaction, but instead show an alternating pattern of flagellar activity associated with peaks and troughs of [Ca(2+)](i). A Ca(2+) store in the rear of the sperm head apparently generates this complex signal, functioning as an '[Ca(2+)](i) oscillator'. We propose that: (i) the acrosome reaction and flagellar beat are regulated by separate Ca(2+) stores; (ii) these stores are mobilized through different mechanisms by different agonists; and (iii) progesterone in vivo acts as a switch for the oscillator which regulates the flagellar beat mode.
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Harper C, Wootton L, Michelangeli F, Lefièvre L, Barratt C, Publicover S. Secretory pathway Ca2+-ATPase (SPCA1) Ca2+ pumps, not SERCAs, regulate complex [Ca2+]i signals in human spermatozoa. J Cell Sci 2005; 118:1673-85. [PMID: 15811949 DOI: 10.1242/jcs.02297] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The sarcoplasmic-endoplasmic reticulum Ca2+-ATPase (SERCA) inhibitors thapsigargin (0.1-1 μM) and cyclopiazonic acid (10 μM), failed to affect resting [Ca2+] in human spermatozoa. Slow progesterone-induced [Ca2+ i]i oscillations in human spermatozoa, which involve cyclic emptying-refilling of an intracellular Ca2+ store were also insensitive to these inhibitors. Non-selective doses of thapsigargin (5-30 μM, 50-300 times the saturating dose for SERCA inhibition), caused elevation of resting [Ca2+]i and partial, dose-dependent disruption of oscillations. A 10-40 μM concentration of bis(2-hydroxy-3-tert-butyl-5-methyl-phenyl)methane (bis-phenol), which inhibits both thapsigargin-sensitive and -insensitive microsomal Ca2+ ATPases, caused elevation of resting [Ca2+]i and inhibition of [Ca2+]i oscillations at doses consistent with inhibition of thapsigargin-resistant, microsomal ATPase and liberation of stored Ca2+. Low doses of bis-phenol had marked effects on [Ca2+]i oscillation kinetics. Application of the drug to cells previously stimulated with progesterone had effects very similar to those observed when it was applied to unstimulated cells, suggesting that the sustained Ca2+ influx induced by progesterone is not mediated via mobilisation of Ca2+ stores. Western blotting for human sperm proteins showed expression of secretory pathway Ca2+ ATPase (SPCA1). Immunolocalisation studies revealed expression of SPCA1 in all cells in an area behind the nucleus, extending into the midpiece. Staining for SERCA, carried out in parallel, detected no expression with either technique. We conclude that: (1) intracellular Ca2+ store(s) and store-dependent [Ca2+]i oscillations in human spermatozoa rely primarily on a thapsigargin/cyclopiazonic acid-insensitive Ca2+ pump, which is not a SERCA as characterised in somatic cells; (2) effects of high-dose thapsigargin on spermatozoa primarily reflect non-specific actions on non-SERCAs and; (3) secretory pathway Ca2+ ATPases contribute at least part of this non-SERCA Ca2+ pump activity.
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Affiliation(s)
- Claire Harper
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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McCarty OJT, Zhao Y, Andrew N, Machesky LM, Staunton D, Frampton J, Watson SP. Evaluation of the role of platelet integrins in fibronectin-dependent spreading and adhesion. J Thromb Haemost 2004; 2:1823-33. [PMID: 15456495 DOI: 10.1111/j.1538-7836.2004.00925.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Recent studies have shown that platelet adhesion and subsequent aggregation can occur in vivo in the absence of the two principal platelets adhesive ligands, von Willebrand factor and fibrinogen. These results highlight a possible role for fibronectin in supporting thrombus formation. OBJECTIVE AND METHODS To evaluate the platelet integrins and subsequent activation pathways associated with fibronectin-dependent platelet adhesion utilizing both human and murine platelets. RESULTS Platelets can adhere to fibronectin via the integrin alpha(IIb)beta(3), leading to formation of lamellipodia. This is mediated through an interaction with the tenth type III domain in fibronectin. Spreading on fibronectin promotes alpha(IIb)beta(3)-mediated Ca(2+) mobilization and tyrosine phosphorylation of focal adhesion kinase and phospholipase C gamma2. In contrast, studies with blocking antibodies and mice demonstrate that alpha(5)beta(1) and alpha(v)beta(3) support adhesion and promote formation of filopodia but not lamellipodia or tyrosine phosphorylation of these proteins. Further, neither alpha(5)beta(1) nor alpha(v)beta(3) is able to induce formation of lamellipodia in the presence of platelets agonists, such as collagen-related-peptide (CRP). CONCLUSIONS These observations demonstrate that integrins alpha(5)beta(1) and alpha(v)beta(3) support platelet adhesion and the generation of filopodia but that, in contrast to the integrin alpha(IIb)beta(3), are unable to promote formation of lamellipodia.
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Affiliation(s)
- O J T McCarty
- Centre for Cardiovascular Sciences, The Institute of Biomedical Research, Division of Medical Sciences, The Medical School, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
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Abstract
Progesterone is present at micromolar concentrations in the cumulus matrix, which surrounds mammalian oocytes. Exposure of human spermatozoa to a concentration gradient of progesterone (0-3 microM) to simulate approach to the oocyte induced a slowly developing increase in [Ca(2+)](i) upon which, in many cells, slow oscillations were superimposed. [Ca(2+)](i) oscillations often started at very low progesterone (<10 nm), and their frequency did not change during the subsequent rise in concentration. Oscillations also occurred, but in a much smaller proportion of cells, in response to stepped application of progesterone (3 microM). When progesterone was removed, [Ca(2+)](i) oscillations often persisted or quickly resumed. Superfusion with low-Ca(2+) bathing medium (no added Ca(2+)) did not prevent [Ca(2+)](i) oscillations, but they could be abolished by addition of EGTA or La(3+). Inhibitors of sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPases or inositol trisphosphate signaling had no effect on [Ca(2+)](i) oscillations, but pharmacological manipulation of ryanodine receptors affected both their frequency and amplitude. Staining of live spermatozoa with BODIPY FL-X ryanodine showed localization of ryanodine binding primarily to the caudal part of the head and mid-piece. [Ca(2+)](i) oscillations did not induce acrosome reaction, but in cells generating oscillations, the flagellar beat mode alternated in synchrony with the oscillation cycle. Flagellar bending and lateral movement of the sperm head during [Ca(2+)](i) peaks were markedly increased compared with during [Ca(2+)](i) troughs. This alternating pattern of activity is likely to facilitate zona penetration. These observations show that progesterone initiates unusual and complex store-mediated [Ca(2+)](i) signaling in human spermatozoa and identify a previously unrecognized effect of progesterone in regulating sperm "behavior" during fertilization.
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Affiliation(s)
- Claire V Harper
- School of Biosciences, Medical School, University of Birmingham, Birmingham, UK
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Abstract
'Classical' genomic progesterone receptors appear relatively late in phylogenesis, i.e. it is only in birds and mammals that they are detectable. In the different species, they mediate manifold effects regarding the differentiation of target organ functions, mainly in the reproductive system. Surprisingly, we know little about the physiology, endocrinology, and pharmacology of progesterone and progestins in male gender or men respectively, despite the fact that, as to progesterone secretion and serum progesterone levels, there are no great quantitative differences between men and women (at least outside the luteal phase). In a prospective cohort study of 1026 men with and without cardiovascular disease, we were not able to demonstrate any age-dependent change in serum progesterone concentrations. Progesterone influences spermiogenesis, sperm capacitation/acrosome reaction and testosterone biosynthesis in the Leydig cells. Other progesterone effects in men include those on the central nervous system (CNS) (mainly mediated by 5alpha-reduced progesterone metabolites as so-called neurosteroids), including blocking of gonadotropin secretion, sleep improvement, and effects on tumors in the CNS (meningioma, fibroma), as well as effects on the immune system, cardiovascular system, kidney function, adipose tissue, behavior, and respiratory system. A progestin may stimulate weight gain and appetite in men as well as in women. The detection of progesterone receptor isoforms would have a highly diagnostic value in prostate pathology (benign prostatic hypertrophy and prostate cancer). The modulation of progesterone effects on typical male targets is connected with a great pharmacodynamic variability. The reason for this is that, in men, some important effects of progesterone are mediated non-genomically through different molecular biological modes of action. Therefore, the precise therapeutic manipulation of progesterone actions in the male requires completely new endocrine-pharmacological approaches.
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Kirkman-Brown JC, Barratt CLR, Publicover SJ. Slow calcium oscillations in human spermatozoa. Biochem J 2004; 378:827-32. [PMID: 14606954 PMCID: PMC1223996 DOI: 10.1042/bj20031368] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2003] [Revised: 10/16/2003] [Accepted: 11/07/2003] [Indexed: 11/17/2022]
Abstract
We have used single-cell imaging to investigate intracellular Ca2+ signalling in human spermatozoa stimulated with progesterone (3 microM). In approx. 9% of cells progesterone caused the activation of slow repetitive [Ca2+]i (intracellular Ca2+ concentration) oscillations, with a period of 1-4 min, which persisted for the duration of recording (20-30 min). Pretreatment with nifedipine, which blocks T- and L-type voltage-operated Ca2+ channels in spermatogenic cells, did not modify the characteristics of the oscillations, but reduced the proportion of cells in which they were observed. Stimulation with Bay K 8644 or FPL64176 induced [Ca2+]i oscillations in 5-10% of cells, but their frequency was low (period, 4-5 min). Application of valinomycin (1 microM) to clamp membrane potential at E(K) (equilibrium potential for potassium) did not modify activity in oscillating cells, showing that plasma membrane potential and activation of voltage-operated conductances are not involved in the mechanism by which sperm [Ca2+]i oscillations are generated.
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Lefièvre L, Barratt CLR, Harper CV, Conner SJ, Flesch FM, Deeks E, Moseley FLC, Pixton KL, Brewis IA, Publicover SJ. Physiological and proteomic approaches to studying prefertilization events in the human. Reprod Biomed Online 2003; 7:419-27. [PMID: 14753177 DOI: 10.1016/s1472-6483(10)61885-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
This research aims firstly to understand, in cellular and molecular terms, how a mature human spermatozoon is prepared for fertilization, and secondly, to identify what factors are involved in the initial signalling interactions between the egg and spermatozoon. In order to achieve these objectives, a combination of approaches is being used, including single-cell imaging, patch clamping and proteomics. Single-cell imaging reveals hidden complexity and heterogeneity in signalling responses in spermatozoa. Characterization of cell physiology at the single-cell level must be a future aim, including the study of ion channel expression and function by patch clamping. Proteomic experiments are aimed at identifying defects in protein expression in specific subgroups of men, e.g. those with globozoospermia. A better understanding of prefertilization events will allow the development of non-assisted reproductive therapy, drug-based treatments for male infertility.
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Affiliation(s)
- Linda Lefièvre
- Reproductive Biology and Genetics Research Group, The Medical School, University of Birmingham, UK
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