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Priego Espinosa D, Espinal-Enríquez J, Aldana A, Aldana M, Martínez-Mekler G, Carneiro J, Darszon A. Reviewing mathematical models of sperm signaling networks. Mol Reprod Dev 2024; 91:e23766. [PMID: 39175359 DOI: 10.1002/mrd.23766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2024] [Accepted: 07/22/2024] [Indexed: 08/24/2024]
Abstract
Dave Garbers' work significantly contributed to our understanding of sperm's regulated motility, capacitation, and the acrosome reaction. These key sperm functions involve complex multistep signaling pathways engaging numerous finely orchestrated elements. Despite significant progress, many parameters and interactions among these elements remain elusive. Mathematical modeling emerges as a potent tool to study sperm physiology, providing a framework to integrate experimental results and capture functional dynamics considering biochemical, biophysical, and cellular elements. Depending on research objectives, different modeling strategies, broadly categorized into continuous and discrete approaches, reveal valuable insights into cell function. These models allow the exploration of hypotheses regarding molecules, conditions, and pathways, whenever they become challenging to evaluate experimentally. This review presents an overview of current theoretical and experimental efforts to understand sperm motility regulation, capacitation, and the acrosome reaction. We discuss the strengths and weaknesses of different modeling strategies and highlight key findings and unresolved questions. Notable discoveries include the importance of specific ion channels, the role of intracellular molecular heterogeneity in capacitation and the acrosome reaction, and the impact of pH changes on acrosomal exocytosis. Ultimately, this review underscores the crucial importance of mathematical frameworks in advancing our understanding of sperm physiology and guiding future experimental investigations.
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Affiliation(s)
| | - Jesús Espinal-Enríquez
- Computational Genomics Division, National Institute of Genomic Medicine (INMEGEN), Mexico City, Mexico
| | - Andrés Aldana
- Network Science Institute, Northeastern University, Boston, Massachusetts, USA
| | - Maximino Aldana
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México (UNAM), Mexico City, México
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Gustavo Martínez-Mekler
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México (UNAM), Mexico City, México
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, México
| | - Jorge Carneiro
- Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Lisboa, Portugal
| | - Alberto Darszon
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, México
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de Prelle B, Lybaert P, Gall D. A Minimal Model Shows that a Positive Feedback Loop Between sNHE and SLO3 can Control Mouse Sperm Capacitation. Front Cell Dev Biol 2022; 10:835594. [PMID: 35399518 PMCID: PMC8990769 DOI: 10.3389/fcell.2022.835594] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 02/21/2022] [Indexed: 11/25/2022] Open
Abstract
When mammalian spermatozoa are released in the female reproductive tract, they are incapable of fertilizing the oocyte. They need a prolonged exposure to the alkaline medium of the female genital tract before their flagellum gets hyperactivated and the acrosome reaction can take place, allowing the sperm to interact with the oocyte. Ionic fluxes across the sperm membrane are involved in two essential aspects of capacitation: the increase in intracellular pH and the membrane hyperpolarization. In particular, it has been shown that the SLO3 potassium channel and the sNHE sodium-proton exchanger, two sperm-specific transmembrane proteins, are necessary for the capacitation process to occur. As the SLO3 channel is activated by an increase in intracellular pH and sNHE is activated by hyperpolarization, they act together as a positive feedback system. Mathematical modeling provides a unique tool to capture the essence of a molecular mechanism and can be used to derive insight from the existing data. We have therefore developed a theoretical model formalizing the positive feedback loop between SLO3 and sHNE in mouse epididymal sperm to see if this non-linear interaction can provide the core mechanism explaining the existence of uncapacited and capacitated states. We show that the proposed model can fully explain the switch between the uncapacitated and capacited states and also predicts the existence of a bistable behaviour. Furthermore, our model indicates that SLO3 inhibition, above a certain threshold, can be effective to completely abolish capacitation.
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Affiliation(s)
- Bertrand de Prelle
- Research Laboratory on Human Reproduction, Faculté de Médecine, Université libre de Bruxelles, Brussels, Belgium
| | - Pascale Lybaert
- Research Laboratory on Human Reproduction, Faculté de Médecine, Université libre de Bruxelles, Brussels, Belgium
| | - David Gall
- Research Laboratory on Human Reproduction, Faculté de Médecine, Université libre de Bruxelles, Brussels, Belgium
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3
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Debir B, Meaney C, Kohandel M, Unlu MB. The role of calcium oscillations in the phenotype selection in endothelial cells. Sci Rep 2021; 11:23781. [PMID: 34893636 PMCID: PMC8664853 DOI: 10.1038/s41598-021-02720-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/07/2021] [Indexed: 11/10/2022] Open
Abstract
Angiogenesis is an important process in the formation and maintenance of tissues which is driven by a complex system of intracellular and intercellular signaling mechanisms. Endothelial cells taking part in early angiogenesis must select their phenotype as either a tip cells (leading, migratory) or a stalk cells (following). Recent experiments have demonstrated that rapid calcium oscillations within active cells characterize this phenotype selection process and that these oscillations play a necessary role in governing phenotype selection and eventual vessel architecture. In this work, we develop a mathematical model capable of describing these oscillations and their role in phenotype selection then use it to improve our understanding of the biological mechanisms at play. We developed a model based on two previously published and experimentally validated mathematical models of calcium and angiogenesis then use our resulting model to simulate various multi-cell scenarios. We are able to capture essential calcium oscillation dynamics and intercellular communication between neighboring cells. The results of our model show that although the late DLL4 (a transmembrane protein that activates Notch pathway) levels of a cell are connected with its initial IP3 (Inositol 1,4,5-trisphosphate) level, cell-to-cell communication determines its eventual phenotype.
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Affiliation(s)
- Birses Debir
- Department of Physics, Bogazici University, 34342, Istanbul, Turkey.
| | - Cameron Meaney
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada
| | - Mohammad Kohandel
- Department of Applied Mathematics, University of Waterloo, Waterloo, ON, Canada
| | - M Burcin Unlu
- Department of Physics, Bogazici University, 34342, Istanbul, Turkey
- Hokkaido University, Global Station for Quantum Medical Science and Engineering, Global Institution for Collaborative Research and Education (GI-CoRE), Sapporo, 060-8648, Japan
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4
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Aguado-García A, Priego-Espinosa DA, Aldana A, Darszon A, Martínez-Mekler G. Mathematical model reveals that heterogeneity in the number of ion transporters regulates the fraction of mouse sperm capacitation. PLoS One 2021; 16:e0245816. [PMID: 34793454 PMCID: PMC8601445 DOI: 10.1371/journal.pone.0245816] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Accepted: 10/20/2021] [Indexed: 12/03/2022] Open
Abstract
Capacitation is a complex maturation process mammalian sperm must undergo in the female genital tract to be able to fertilize an egg. This process involves, amongst others, physiological changes in flagellar beating pattern, membrane potential, intracellular ion concentrations and protein phosphorylation. Typically, in a capacitation medium, only a fraction of sperm achieve this state. The cause for this heterogeneous response is still not well understood and remains an open question. Here, one of our principal results is to develop a discrete regulatory network, with mostly deterministic dynamics in conjunction with some stochastic elements, for the main biochemical and biophysical processes involved in the early events of capacitation. The model criterion for capacitation requires the convergence of specific levels of a select set of nodes. Besides reproducing several experimental results and providing some insight on the network interrelations, the main contribution of the model is the suggestion that the degree of variability in the total amount and individual number of ion transporters among spermatozoa regulates the fraction of capacitated spermatozoa. This conclusion is consistent with recently reported experimental results. Based on this mathematical analysis, experimental clues are proposed for the control of capacitation levels. Furthermore, cooperative and interference traits that become apparent in the modelling among some components also call for future theoretical and experimental studies.
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Affiliation(s)
- Alejandro Aguado-García
- Instituto de Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, México
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | | | - Andrés Aldana
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, CDMX, México
| | - Alberto Darszon
- Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Gustavo Martínez-Mekler
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, CDMX, México
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Occurrence of Calcium Oscillations in Human Spermatozoa Is Based on Spatial Signaling Enzymes Distribution. Int J Mol Sci 2021; 22:ijms22158018. [PMID: 34360784 PMCID: PMC8347727 DOI: 10.3390/ijms22158018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/15/2021] [Accepted: 07/21/2021] [Indexed: 11/17/2022] Open
Abstract
In human spermatozoa, calcium dynamics control most of fertilization events. Progesterone, present in the female reproductive system, can trigger several types of calcium responses, such as low-frequency oscillations. Here we aimed to identify the mechanisms of progesterone-induced calcium signaling in human spermatozoa. Progesterone-induced activation of fluorophore-loaded spermatozoa was studied by fluorescent microscopy. Two computational models were developed to describe the spermatozoa calcium responses: a homogeneous one based on a system of ordinary differential equations and a three-dimensional one with added space dimensions and diffusion for the cytosolic species. In response to progesterone, three types of calcium responses were observed in human spermatozoa: a single transient rise of calcium concentration in cytosol, a steady elevation, or low-frequency oscillations. The homogenous model provided qualitative description of the oscillatory and the single spike responses, while the three-dimensional model captured the calcium peak shape and the frequency of calcium oscillations. The model analysis demonstrated that an increase in the calcium diffusion coefficient resulted in the disappearance of the calcium oscillations. Additionally, in silico analysis suggested that the spatial distribution of calcium signaling enzymes governs the appearance of calcium oscillations in progesterone-activated human spermatozoa.
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Torrezan-Nitao E, Brown SG, Mata-Martínez E, Treviño CL, Barratt C, Publicover S. [Ca2+]i oscillations in human sperm are triggered in the flagellum by membrane potential-sensitive activity of CatSper. Hum Reprod 2021; 36:293-304. [PMID: 33305795 DOI: 10.1093/humrep/deaa302] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 09/22/2020] [Indexed: 12/15/2022] Open
Abstract
STUDY QUESTION How are progesterone (P4)-induced repetitive intracellular Ca2+ concentration ([Ca2+]i) signals (oscillations) in human sperm generated? SUMMARY ANSWER P4-induced [Ca2+]i oscillations are generated in the flagellum by membrane potential (Vm)-sensitive Ca2+-influx through CatSper channels. WHAT IS KNOWN ALREADY A subset of human sperm display [Ca2+]i oscillations that regulate flagellar beating and acrosome reaction. Although pharmacological manipulations indicate involvement of stored Ca2+ in these oscillations, influx of extracellular Ca2+ is also required. STUDY DESIGN, SIZE, DURATION This was a laboratory study that used >20 sperm donors and involved more than 100 separate experiments and analysis of more than 1000 individual cells over a period of 2 years. PARTICIPANTS/MATERIALS, SETTING, METHODS Semen donors and patients were recruited in accordance with local ethics approval from Birmingham University and Tayside ethics committees. [Ca2+]i responses and Vm of individual cells were examined by fluorescence imaging and whole-cell current clamp. MAIN RESULTS AND THE ROLE OF CHANCE P4-induced [Ca2+]i oscillations originated in the flagellum, spreading to the neck and head (latency of 1-2 s). K+-ionophore valinomycin (1 µM) was used to investigate the role of membrane potential (Vm). Direct assessment by whole-cell current-clamp confirmed that Vm in valinomycin-exposed cells was determined primarily by K+ equilibrium potential (EK) and was rapidly 'reset' upon manipulation of [K+]o. Pre-treatment of sperm with valinomycin ([K+]o = 5.4 mM) had no effect on the P4-induced [Ca2+] transient (P = 0.95; eight experiments), but application of valinomycin to P4-pretreated sperm suppressed activity in 82% of oscillating cells (n = 257; P = 5 × 10-55 compared to control) and significantly reduced both the amplitude and frequency of persisting oscillations (P = 0.0001). Upon valinomycin washout, oscillations re-started in most cells. When valinomycin was applied in saline with elevated [K+], the inhibitory effect of valinomycin was reduced and was dependent on EK (P = 10-25). Amplitude and frequency of [Ca2+]i oscillations that persisted in the presence of valinomycin showed similar sensitivity to EK (P < 0.01). The CatSper inhibitor RU1968 (4.8 and 11 µM) caused immediate and reversible arrest of activity in 36% and 96% of oscillating cells, respectively (P < 10-10). Quinidine (300 µM) which blocks the sperm K+ current (IKsper) completely, inhibited [Ca2+]i oscillations. LARGE SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION This was an in-vitro study and caution must be taken when extrapolating these results to in-vivo regulation of sperm. WIDER IMPLICATIONS OF THE FINDINGS [Ca2+]i oscillations in human sperm are functionally important and their absence is associated with failed fertilisation at IVF. The data reported here provide new understanding of the mechanisms that underlie the regulation and generation (or failure) of these oscillations. STUDY FUNDING/COMPETING INTEREST(S) E.T.-N. was in receipt of a postgraduate scholarship from the CAPES Foundation (Ministry of Education, Brazil). E.M-M received travel funds from the Programa de Apoyo a los Estudios de Posgrado (Maestria y Doctorado en Ciencias Bioquimicas-Universidad Autonoma de Mexico). SGB and CLRB are recipients of a Chief Scientist Office (NHS Scotland) grant TCS/17/28. The authors have no conflicts of interest.
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Affiliation(s)
| | - Sean G Brown
- School of Applied Sciences, Division of Health Sciences, Abertay University, Dundee DD11HG, UK
| | - Esperanza Mata-Martínez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Claudia L Treviño
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Christopher Barratt
- Systems Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee DD19SY, UK
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7
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Rahban R, Nef S. CatSper: The complex main gate of calcium entry in mammalian spermatozoa. Mol Cell Endocrinol 2020; 518:110951. [PMID: 32712386 DOI: 10.1016/j.mce.2020.110951] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2020] [Revised: 07/17/2020] [Accepted: 07/20/2020] [Indexed: 02/06/2023]
Abstract
Calcium ions (Ca2+) are involved in nearly every aspect of cellular life. They are one of the most abundant elements in mammals and play a vital role in physiological and biochemical processes acting mainly as intracellular messengers. In spermatozoa, several key functions are regulated by cytoplasmic Ca2+ concentration such as sperm capacitation, chemotaxis, hyperactive motility, and acrosome reaction. The sperm-specific ion channel CatSper is the principal calcium channel in sperm mediating the calcium influx into the sperm flagellum and acting as an essential modulator of downstream mechanisms involved in fertilization. This review aims to provide insights into the structure, localization, and function of the mammalian CatSper channel, primarily human and mice. The activation of CatSper by progesterone and prostaglandins, as well as the ligand-independent regulation of the channel by a change in the membrane voltage and intracellular pH are going to be addressed. Finally, major questions, challenges, and perspectives are discussed.
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Affiliation(s)
- Rita Rahban
- Swiss Centre for Applied Human Toxicology (SCAHT), Switzerland; Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, Rue Michel-Servet 1, 1206, Geneva, Switzerland.
| | - Serge Nef
- Swiss Centre for Applied Human Toxicology (SCAHT), Switzerland; Department of Genetic Medicine and Development, Faculty of Medicine, University of Geneva, Rue Michel-Servet 1, 1206, Geneva, Switzerland.
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8
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Carichino L, Olson SD. Emergent three-dimensional sperm motility: coupling calcium dynamics and preferred curvature in a Kirchhoff rod model. MATHEMATICAL MEDICINE AND BIOLOGY-A JOURNAL OF THE IMA 2020; 36:439-469. [PMID: 30325451 DOI: 10.1093/imammb/dqy015] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Revised: 09/11/2018] [Accepted: 09/17/2018] [Indexed: 11/15/2022]
Abstract
Changes in calcium concentration along the sperm flagellum regulate sperm motility and hyperactivation, characterized by an increased flagellar bend amplitude and beat asymmetry, enabling the sperm to reach and penetrate the ovum (egg). The signalling pathways by which calcium increases within the flagellum are well established. However, the exact mechanisms of how calcium regulates flagellar bending are still under investigation. We extend our previous model of planar flagellar bending by developing a fluid-structure interaction model that couples the 3D motion of the flagellum in a viscous Newtonian fluid with the evolving calcium concentration. The flagellum is modelled as a Kirchhoff rod: an elastic rod with preferred curvature and twist. The calcium dynamics are represented as a 1D reaction-diffusion model on a moving domain, the flagellum. The two models are coupled assuming that the preferred curvature and twist of the sperm flagellum depend on the local calcium concentration. To investigate the effect of calcium on sperm motility, we compare model results of flagellar bend amplitude and swimming speed for three cases: planar, helical (spiral with equal amplitude in both directions), and quasi-planar (spiral with small amplitude in one direction). We observe that for the same parameters, the planar swimmer is faster and a turning motion is more clearly observed when calcium coupling is accounted for in the model. In the case of flagellar bending coupled to the calcium concentration, we observe emergent trajectories that can be characterized as a hypotrochoid for both quasi-planar and helical bending.
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Affiliation(s)
- Lucia Carichino
- Department of Mathematical Sciences, Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA, USA
| | - Sarah D Olson
- Department of Mathematical Sciences, Worcester Polytechnic Institute, 100 Institute Rd, Worcester, MA, USA
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9
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The Presence of Seminal Plasma during Liquid Storage of Pig Spermatozoa at 17 °C Modulates Their Ability to Elicit In Vitro Capacitation and Trigger Acrosomal Exocytosis. Int J Mol Sci 2020; 21:ijms21124520. [PMID: 32630462 PMCID: PMC7350249 DOI: 10.3390/ijms21124520] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 06/24/2020] [Accepted: 06/24/2020] [Indexed: 12/14/2022] Open
Abstract
Although seminal plasma is essential to maintain sperm integrity and function, it is diluted/removed prior to liquid storage and cryopreservation in most mammalian species. This study sought to evaluate, using the pig as a model, whether storing semen in the presence of seminal plasma affects the sperm ability to elicit in vitro capacitation and acrosomal exocytosis. Upon collection, seminal plasma was separated from sperm samples, which were diluted in a commercial extender, added with seminal plasma (15% or 30%), and stored at 17 °C for 48 or 72 h. Sperm cells were subsequently exposed to capacitating medium for 4 h, and then added with progesterone to induce acrosomal exocytosis. Sperm motility, acrosome integrity, membrane lipid disorder, intracellular Ca2+ levels, mitochondrial activity, and tyrosine phosphorylation levels of glycogen synthase kinase-3 (GSK3)α/β were determined after 0, 2, and 4 h of incubation, and after 5, 30, and 60 min of progesterone addition. Results showed that storing sperm at 17 °C with 15% or 30% seminal plasma led to reduced percentages of viable spermatozoa exhibiting an exocytosed acrosome, mitochondrial membrane potential, intracellular Ca2+ levels stained by Fluo3, and tyrosine phosphorylation levels of GSK3α/β after in vitro capacitation and progesterone-induced acrosomal exocytosis. Therefore, the direct contact between spermatozoa and seminal plasma during liquid storage at 17 °C modulated their ability to elicit in vitro capacitation and undergo acrosomal exocytosis, via signal transduction pathways involving Ca2+ and Tyr phosphorylation of GSK3α/β. Further research is required to address whether such a modulating effect has any impact upon sperm fertilizing ability.
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Leemans B, Stout TAE, De Schauwer C, Heras S, Nelis H, Hoogewijs M, Van Soom A, Gadella BM. Update on mammalian sperm capacitation: how much does the horse differ from other species? Reproduction 2020; 157:R181-R197. [PMID: 30721132 DOI: 10.1530/rep-18-0541] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Accepted: 02/04/2019] [Indexed: 12/21/2022]
Abstract
In contrast to various other mammalian species, conventional in vitro fertilization (IVF) with horse gametes is not reliably successful. In particular, stallion spermatozoa fails to penetrate the zona pellucida, most likely due to incomplete activation of stallion spermatozoa (capacitation) under in vitro conditions. In other mammalian species, specific capacitation triggers have been described; unfortunately, none of these is able to induce full capacitation in stallion spermatozoa. Nevertheless, knowledge of capacitation pathways and their molecular triggers might improve our understanding of capacitation-related events observed in stallion sperm. When sperm cells are exposed to appropriate capacitation triggers, several molecular and biochemical changes should be induced in the sperm plasma membrane and cytoplasm. At the level of the sperm plasma membrane, (1) an increase in membrane fluidity, (2) cholesterol depletion and (3) lipid raft aggregation should occur consecutively; the cytoplasmic changes consist of protein tyrosine phosphorylation and elevated pH, cAMP and Ca2+ concentrations. These capacitation-related events enable the switch from progressive to hyperactivated motility of the sperm cells, and the induction of the acrosome reaction. These final capacitation triggers are indispensable for sperm cells to migrate through the viscous oviductal environment, penetrate the cumulus cells and zona pellucida and, finally, fuse with the oolemma. This review will focus on molecular aspects of sperm capacitation and known triggers in various mammalian species. Similarities and differences with the horse will be highlighted to improve our understanding of equine sperm capacitation/fertilizing events.
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Affiliation(s)
- Bart Leemans
- Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Tom A E Stout
- Department of Equine Sciences, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.,Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Catharina De Schauwer
- Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Sonia Heras
- Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Hilde Nelis
- Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Maarten Hoogewijs
- Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Ann Van Soom
- Department of Reproduction, Obstetrics and Herd Health, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Bart M Gadella
- Department of Farm Animal Health, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands.,Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
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11
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A simple mechanochemical model for calcium signalling in embryonic epithelial cells. J Math Biol 2019; 78:2059-2092. [PMID: 30826846 PMCID: PMC6560504 DOI: 10.1007/s00285-019-01333-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2018] [Revised: 11/14/2018] [Indexed: 12/17/2022]
Abstract
Calcium signalling is one of the most important mechanisms of information propagation in the body. In embryogenesis the interplay between calcium signalling and mechanical forces is critical to the healthy development of an embryo but poorly understood. Several types of embryonic cells exhibit calcium-induced contractions and many experiments indicate that calcium signals and contractions are coupled via a two-way mechanochemical feedback mechanism. We present a new analysis of experimental data that supports the existence of this coupling during apical constriction. We then propose a simple mechanochemical model, building on early models that couple calcium dynamics to the cell mechanics and we replace the hypothetical bistable calcium release with modern, experimentally validated calcium dynamics. We assume that the cell is a linear, viscoelastic material and we model the calcium-induced contraction stress with a Hill function, i.e. saturating at high calcium levels. We also express, for the first time, the "stretch-activation" calcium flux in the early mechanochemical models as a bottom-up contribution from stretch-sensitive calcium channels on the cell membrane. We reduce the model to three ordinary differential equations and analyse its bifurcation structure semi-analytically as two bifurcation parameters vary-the [Formula: see text] concentration, and the "strength" of stretch activation, [Formula: see text]. The calcium system ([Formula: see text], no mechanics) exhibits relaxation oscillations for a certain range of [Formula: see text] values. As [Formula: see text] is increased the range of [Formula: see text] values decreases and oscillations eventually vanish at a sufficiently high value of [Formula: see text]. This result agrees with experimental evidence in embryonic cells which also links the loss of calcium oscillations to embryo abnormalities. Furthermore, as [Formula: see text] is increased the oscillation amplitude decreases but the frequency increases. Finally, we also identify the parameter range for oscillations as the mechanical responsiveness factor of the cytosol increases. This work addresses a very important and not well studied question regarding the coupling between chemical and mechanical signalling in embryogenesis.
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12
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Harayama H. Flagellar hyperactivation of bull and boar spermatozoa. Reprod Med Biol 2018; 17:442-448. [PMID: 30377397 PMCID: PMC6194283 DOI: 10.1002/rmb2.12227] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 07/26/2018] [Accepted: 07/31/2018] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND In mammals, flagellar hyperactivation is indispensable to sperm fertilization with oocytes in vivo, although there are species differences in regulatory mechanisms for this event. In this study, I reviewed researches regarding hyperactivation of bull and boar spermatozoa, in comparison with those of spermatozoa from other species. METHODS Recent publications regarding sperm hyperactivation were collected and summarized. RESULTS MAIN FINDINGS In bull and boar spermatozoa, there are two types of hyperactivation "full-type hyperactivation and nonfull-type hyperactivation" which are equivalent to anti-hock hyperactivation and pro-hock hyperactivation of mouse spermatozoa, respectively, on the basis of the flagellar parts exhibiting asymmetrical beating. Full-type hyperactivation is initiated in response to a rapid increase of cytoplasmic Ca2+ in the connecting/middle and principal pieces by the mobilization of this divalent ion from extracellular space and internal store through cation channels. Regulatory molecules for the increase of cytoplasmic Ca2+ in the connecting/middle pieces are probably different from those in the principal pieces. CONCLUSION I have proposed a hypothesis on the regulation of full-type hyperactivation by the distinct signaling cascades leading to the increase in cytoplasmic Ca2+ between the connecting/middle and principal pieces of bull and boar spermatozoa.
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Affiliation(s)
- Hiroshi Harayama
- Division of Animal Science, Department of Bioresource Science, Graduate School of Agricultural ScienceKobe UniversityKobeJapan
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13
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Scherr T, Knapp GL, Guitreau A, Park DSW, Tiersch T, Nandakumar K, Monroe WT. Microfluidics and numerical simulation as methods for standardization of zebrafish sperm cell activation. Biomed Microdevices 2015; 17:65. [PMID: 26026298 DOI: 10.1007/s10544-015-9957-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Sperm cell activation plays a critical role in a range of biological and engineering processes, from fertilization to cryopreservation protocol evaluation. Across a range of species, ionic and osmotic effects have been discovered that lead to activation. Sperm cells of zebrafish (Danio rerio) initiate motility in a hypoosmotic environment. In this study, we employ a microfluidic mixer for the purpose of rapidly diluting the extracellular medium to initiate the onset of cell motility. The use of a microchannel offers a rapid and reproducible mixing profile throughout the device. This greatly reduces variability from trial to trial relative to the current methods of analysis. Coupling these experiments with numerical simulations, we were able to investigate the dynamics of intracellular osmolality as each cell moves along its path through the micromixer. Our results suggest that intracellular osmolality, and hence intracellular ion concentration, only slightly decreases, contrary to the common thought that larger changes in these parameters are required for activation. Utilizing this framework, microfluidics for controlled extracellular environments and associated numerical modeling, has practical applicability in standardizing high-throughput aquatic sperm activation, and more fundamentally, investigations of the intracellular environment leading to motility.
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Affiliation(s)
- Thomas Scherr
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, 37235, USA
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14
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Correia J, Michelangeli F, Publicover S. Regulation and roles of Ca2+ stores in human sperm. Reproduction 2015; 150:R65-76. [PMID: 25964382 PMCID: PMC4497595 DOI: 10.1530/rep-15-0102] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Accepted: 05/11/2015] [Indexed: 12/16/2022]
Abstract
[Ca(2)(+)]i signalling is a key regulatory mechanism in sperm function. In mammalian sperm the Ca(2)(+)-permeable plasma membrane ion channel CatSper is central to [Ca(2)(+)]i signalling, but there is good evidence that Ca(2)(+) stored in intracellular organelles is also functionally important. Here we briefly review the current understanding of the diversity of Ca(2)(+) stores and the mechanisms for the regulation of their activity. We then consider the evidence for the involvement of these stores in [Ca(2)(+)]i signalling in mammalian (primarily human) sperm, the agonists that may activate these stores and their role in control of sperm function. Finally we consider the evidence that membrane Ca(2)(+) channels and stored Ca(2)(+) may play discrete roles in the regulation of sperm activities and propose a mechanism by which these different components of the sperm Ca(2)(+)-signalling apparatus may interact to generate complex and spatially diverse [Ca(2)(+)]i signals.
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Affiliation(s)
- Joao Correia
- School of BiosciencesUniversity of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | | | - Stephen Publicover
- School of BiosciencesUniversity of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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15
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16
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Loux SC, Macías-Garcia B, González-Fernández L, Canesin HD, Varner DD, Hinrichs K. Regulation of axonemal motility in demembranated equine sperm. Biol Reprod 2014; 91:152. [PMID: 25339104 DOI: 10.1095/biolreprod.114.122804] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Equine in vitro fertilization is not yet successful because equine sperm do not effectively capacitate in vitro. Results of previous studies suggest that this may be due to failure of induction of hyperactivated motility in equine sperm under standard capacitating conditions. To evaluate factors directly affecting axonemal motility in equine sperm, we developed a demembranated sperm model and analyzed motility parameters in this model under different conditions using computer-assisted sperm analysis. Treatment of ejaculated equine sperm with 0.02% Triton X-100 for 30 sec maximized both permeabilization and total motility after reactivation. The presence of ATP was required for motility of demembranated sperm after reactivation, but cAMP was not. The calculated intracellular pH of intact equine sperm was 7.14 ± 0.07. Demembranated sperm showed maximal total motility at pH 7. Neither increasing pH nor increasing calcium levels, nor any interaction of the two, induced hyperactivated motility in demembranated equine sperm. Motility of demembranated sperm was maintained at free calcium concentrations as low as 27 pM, and calcium arrested sperm motility at much lower concentrations than those reported in other species. Calcium arrest of sperm motility was not accompanied by flagellar curvature, suggesting a failure of calcium to induce the tonic bend seen in other species and thought to support hyperactivated motility. This indicated an absence, or difference in calcium sensitivity, of the related asymmetric doublet-sliding proteins. These studies show a difference in response to calcium of the equine sperm axoneme to that reported in other species that may be related to the failure of equine sperm to penetrate oocytes in vitro under standard capacitating conditions. Further work is needed to determine the factors that stimulate hyperactivated motility at the axonemal level in equine sperm.
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Affiliation(s)
- Shavahn C Loux
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas
| | - Beatríz Macías-Garcia
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas
| | - Lauro González-Fernández
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas
| | - Heloisa DeSiqueira Canesin
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas
| | - Dickson D Varner
- Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas
| | - Katrin Hinrichs
- Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas Department of Large Animal Clinical Sciences, College of Veterinary Medicine & Biomedical Sciences, Texas A&M University, College Station, Texas
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17
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Albrizio M, Moramarco AM, Nicassio M, Micera E, Zarrilli A, Lacalandra GM. Localization and functional modification of L-type voltage-gated calcium channels in equine spermatozoa from fresh and frozen semen. Theriogenology 2014; 83:421-9. [PMID: 25459425 DOI: 10.1016/j.theriogenology.2014.10.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Revised: 10/01/2014] [Accepted: 10/05/2014] [Indexed: 01/13/2023]
Abstract
It is well known that insemination of cryopreserved semen always results in lower fertility when compared with fresh semen, but there is an increased interest and demand for frozen equine semen by the major breeder associations because of the utility arising from semen already "on hand" at breeding time. In this article, we report that equine sperm cells express L-type voltage-gated calcium channels; their localization is restricted to sperm neck and to the principal piece of the tail in both fresh and frozen-thawed spermatozoa. We also studied the causes of cryoinjury at the membrane level focusing on the function of L-type calcium channels. We report that in cryopreserved spermatozoa the mean basal value of [Ca(2+)]i is higher than that of spermatozoa from fresh semen (447.130 vs. 288.3 nM; P < 0.001) and L-type channels function differently in response to their agonist and antagonist in relation to semen condition (fresh or frozen-thawed). We found that on addition of agonist to the culture medium, the increase in intracellular calcium concentrations ([Ca(2+)]i) was greater in frozen semen than in fresh semen (Δ[Ca(2+)]i = 124.59 vs. 16.04 nM; P < 0.001), whereas after the addition of antagonist the decrease in [Ca(2+)]i was lower in frozen semen than in fresh semen (Δ[Ca(2+)]i = 32.5 vs. 82.5 nM; P < 0.001). In this article, we also discuss the impact of cryopreservation on sperm physiology.
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Affiliation(s)
- M Albrizio
- Department of Emergency and Organs Transplantation (DETO), Section of Veterinary Clinics and Animal Productions, University of Bari "Aldo Moro," Valenzano, Bari, Italy.
| | - A M Moramarco
- Department of Emergency and Organs Transplantation (DETO), Section of Veterinary Clinics and Animal Productions, University of Bari "Aldo Moro," Valenzano, Bari, Italy
| | - M Nicassio
- Department of Emergency and Organs Transplantation (DETO), Section of Veterinary Clinics and Animal Productions, University of Bari "Aldo Moro," Valenzano, Bari, Italy
| | - E Micera
- Department of Emergency and Organs Transplantation (DETO), Section of Veterinary Clinics and Animal Productions, University of Bari "Aldo Moro," Valenzano, Bari, Italy
| | - A Zarrilli
- Department of Emergency and Organs Transplantation (DETO), Section of Veterinary Clinics and Animal Productions, University of Bari "Aldo Moro," Valenzano, Bari, Italy
| | - G M Lacalandra
- Department of Emergency and Organs Transplantation (DETO), Section of Veterinary Clinics and Animal Productions, University of Bari "Aldo Moro," Valenzano, Bari, Italy
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18
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The dynamics of sperm detachment from epithelium in a coupled fluid-biochemical model of hyperactivated motility. J Theor Biol 2014; 354:81-94. [PMID: 24685890 DOI: 10.1016/j.jtbi.2014.03.024] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Revised: 03/07/2014] [Accepted: 03/14/2014] [Indexed: 11/21/2022]
Abstract
Hyperactivation in mammalian sperm is characterized by a high-amplitude, asymmetric flagellar waveform. A mechanical advantage of this hyperactivated waveform has been hypothesized to be the promotion of flagellar detachment from oviductal epithelium. In order to investigate the dynamics of a free-swimming sperm׳s binding and escaping from a surface, we present an integrative model that couples flagellar force generation and a viscous, incompressible fluid. The elastic flagellum is actuated by a preferred curvature model that depends upon an evolving calcium profile along its length. In addition, forces that arise due to elastic bonds that form and break between the flagellar head and the surface are accounted for. As in recent laboratory experiments, we find that a hyperactive waveform does result in frequent detaching and binding dynamics that is not observed for symmetric flagellar beats. Moreover, we demonstrate that flagellar behavior depends strongly on the assumptions of the bond model, suggesting the need for more experimental investigation of the biochemistry of epithelial bonding and the shedding of binding proteins on the sperm head.
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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] [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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20
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Loux SC, Crawford KR, Ing NH, González-Fernández L, Macías-García B, Love CC, Varner DD, Velez IC, Choi YH, Hinrichs K. CatSper and the Relationship of Hyperactivated Motility to Intracellular Calcium and pH Kinetics in Equine Sperm1. Biol Reprod 2013; 89:123. [DOI: 10.1095/biolreprod.113.111708] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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21
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Mortimer D, Barratt CLR, Björndahl L, de Jager C, Jequier AM, Muller CH. What should it take to describe a substance or product as 'sperm-safe'. Hum Reprod Update 2013; 19 Suppl 1:i1-45. [PMID: 23552271 DOI: 10.1093/humupd/dmt008] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Male reproductive potential continues to be adversely affected by many environmental, industrial and pharmaceutical toxins. Pre-emptive testing for reproductive toxicological (side-)effects remains limited, or even non-existent. Many products that come into direct contact with spermatozoa lack adequate testing for the absence of adverse effects, and numerous products that are intended for exposure to spermatozoa have only a general assumption of safety based on the absence of evidence of actual harm. Such assumptions can have unfortunate adverse impacts on at-risk individuals (e.g. couples who are trying to conceive), illustrating a clear need for appropriate up-front testing to establish actual 'sperm safety'. METHODS After compiling a list of general areas within the review's scope, relevant literature and other information was obtained from the authors' personal professional libraries and archives, and supplemented as necessary using PubMed and Google searches. Review by co-authors identified and eliminated errors of omission or bias. RESULTS This review provides an overview of the broad range of substances, materials and products that can affect male fertility, especially through sperm fertilizing ability, along with a discussion of practical methods and bioassays for their evaluation. It is concluded that products can only be claimed to be 'sperm-safe' after performing objective, properly designed experimental studies; extrapolation from supposed predicate products or other assumptions cannot be trusted. CONCLUSIONS We call for adopting the precautionary principle, especially when exposure to a product might affect not only a couple's fertility potential but also the health of resulting offspring and perhaps future generations.
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Affiliation(s)
- David Mortimer
- Oozoa Biomedical Inc., Caulfeild Village, West Vancouver, BC, Canada.
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22
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Alasmari W, Costello S, Correia J, Oxenham SK, Morris J, Fernandes L, Ramalho-Santos J, Kirkman-Brown J, Michelangeli F, Publicover S, Barratt CLR. Ca2+ signals generated by CatSper and Ca2+ stores regulate different behaviors in human sperm. J Biol Chem 2013; 288:6248-58. [PMID: 23344959 PMCID: PMC3585060 DOI: 10.1074/jbc.m112.439356] [Citation(s) in RCA: 114] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
[Ca2+]i signaling regulates sperm motility, enabling switching between functionally different behaviors that the sperm must employ as it ascends the female tract and fertilizes the oocyte. We report that different behaviors in human sperm are recruited according to the Ca2+ signaling pathway used. Activation of CatSper (by raising pHi or stimulating with progesterone) caused sustained [Ca2+]i elevation but did not induce hyperactivation, the whiplash-like behavior required for progression along the oviduct and penetration of the zona pellucida. In contrast, penetration into methylcellulose (mimicking penetration into cervical mucus or cumulus matrix) was enhanced by activation of CatSper. NNC55-0396, which abolishes CatSper currents in human sperm, inhibited this effect. Treatment with 5 μm thimerosal to mobilize stored Ca2+ caused sustained [Ca2+]i elevation and induced strong, sustained hyperactivation that was completely insensitive to NNC55-0396. Thimerosal had no effect on penetration into methylcellulose. 4-Aminopyridine, a powerful modulator of sperm motility, both raised pHi and mobilized Ca2+ stored in sperm (and from microsomal membrane preparations). 4-Aminopyridine-induced hyperactivation even in cells suspended in Ca2+-depleted medium and also potentiated penetration into methylcellulose. The latter effect was sensitive to NNC55-039, but induction of hyperactivation was not. We conclude that these two components of the [Ca2+]i signaling apparatus have strikingly different effects on sperm motility. Furthermore, since stored Ca2+ at the sperm neck can be mobilized by Ca2+-induced Ca2+ release, we propose that CatSper activation can elicit functionally different behaviors according to the sensitivity of the Ca2+ store, which may be regulated by capacitation and NO from the cumulus.
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Affiliation(s)
- Wardah Alasmari
- From the Reproductive and Developmental Biology, Medical School, University of Dundee, Ninewells Hospital, Dundee DD1 9SY, Scotland, United Kingdom
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23
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Mata-Rocha M, Alvarado-Cuevas E, Hernández-Sánchez J, Cerecedo D, Felix R, Hernández-Reyes A, Tesoro-Cruz E, Oviedo N. Molecular cloning and analysis of the Catsper1 gene promoter. ACTA ACUST UNITED AC 2013; 19:336-47. [DOI: 10.1093/molehr/gat003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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Olson SD, Suarez SS, Fauci LJ. Coupling biochemistry and hydrodynamics captures hyperactivated sperm motility in a simple flagellar model. J Theor Biol 2011; 283:203-16. [PMID: 21669209 DOI: 10.1016/j.jtbi.2011.05.036] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 05/18/2011] [Accepted: 05/23/2011] [Indexed: 12/12/2022]
Abstract
Hyperactivation in mammalian sperm is characterized by highly asymmetrical waveforms and an increase in the amplitude of flagellar bends. It is important for the sperm to be able to achieve hyperactivated motility in order to reach and fertilize the egg. Calcium (Ca(2+)) dynamics are known to play a large role in the initiation and maintenance of hyperactivated motility. Here we present an integrative model that couples the CatSper channel mediated Ca(2+) dynamics of hyperactivation to a mechanical model of an idealized sperm flagellum in a 3-d viscous, incompressible fluid. The mechanical forces are due to passive stiffness properties and active bending moments that are a function of the local Ca(2+) concentration along the length of the flagellum. By including an asymmetry in bending moments to reflect an asymmetry in the axoneme's response to Ca(2+), we capture the transition from activated motility to hyperactivated motility. We examine the effects of elastic properties of the flagellum and the Ca(2+) dynamics on the overall swimming patterns. The swimming velocities of the model flagellum compare well with data for hyperactivated mouse sperm.
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Affiliation(s)
- Sarah D Olson
- Mathematics Department, Tulane University, 6823 St Charles Ave., New Orleans, LA 70118, USA.
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25
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Olson SD, Fauci LJ, Suarez SS. Mathematical modeling of calcium signaling during sperm hyperactivation. Mol Hum Reprod 2011; 17:500-10. [PMID: 21606121 DOI: 10.1093/molehr/gar040] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Mammalian sperm must hyperactivate in order to fertilize oocytes. Hyperactivation is characterized by highly asymmetrical flagellar bending. It serves to move sperm out of the oviductal reservoir and to penetrate viscoelastic fluids, such as the cumulus matrix. It is absolutely required for sperm penetration of the oocyte zona pellucida. In order for sperm to hyperactivate, cytoplasmic Ca(2+) levels in the flagellum must increase. The major mechanism for providing Ca(2+) to the flagellum, at least in mice, are CatSper channels in the plasma membrane of the principal piece of the flagellum, because sperm from CatSper null males are unable to hyperactivate. There is some evidence for the existence of other types of Ca(2+) channels in sperm, but their roles in hyperactivation have not been clearly established. Another Ca(2+) source for hyperactivation is the store in the redundant nuclear envelope of sperm. To stabilize levels of cytoplasmic Ca(2+), sperm contain Ca(2+) ATPase and exchangers. The interactions between channels, Ca(2+) ATPases, and exchangers are poorly understood; however, mathematical modeling can help to elucidate how they work together to produce the patterns of changes in Ca(2+) levels that have been observed in sperm. Mathematical models can reveal interesting and unexpected relationships, suggesting experiments to be performed in the laboratory. Mathematical analysis of Ca(2+) dynamics has been used to develop a model for Ca(2+) clearance and for CatSper-mediated Ca(2+) dynamics. Models may also be used to understand how Ca(2+) patterns produce flagellar bending patterns of sperm in fluids of low and high viscosity and elasticity.
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Affiliation(s)
- S D Olson
- Department of Mathematics, Tulane University, New Orleans, LA 70115 USA
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26
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Progesterone activates the principal Ca2+ channel of human sperm. Nature 2011; 471:387-91. [PMID: 21412339 DOI: 10.1038/nature09767] [Citation(s) in RCA: 437] [Impact Index Per Article: 33.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2010] [Accepted: 12/17/2010] [Indexed: 01/14/2023]
Abstract
Steroid hormone progesterone released by cumulus cells surrounding the egg is a potent stimulator of human spermatozoa. It attracts spermatozoa towards the egg and helps them penetrate the egg's protective vestments. Progesterone induces Ca(2+) influx into spermatozoa and triggers multiple Ca(2+)-dependent physiological responses essential for successful fertilization, such as sperm hyperactivation, acrosome reaction and chemotaxis towards the egg. As an ovarian hormone, progesterone acts by regulating gene expression through a well-characterized progesterone nuclear receptor. However, the effect of progesterone upon transcriptionally silent spermatozoa remains unexplained and is believed to be mediated by a specialized, non-genomic membrane progesterone receptor. The identity of this non-genomic progesterone receptor and the mechanism by which it causes Ca(2+) entry remain fundamental unresolved questions in human reproduction. Here we elucidate the mechanism of the non-genomic action of progesterone on human spermatozoa by identifying the Ca(2+) channel activated by progesterone. By applying the patch-clamp technique to mature human spermatozoa, we found that nanomolar concentrations of progesterone dramatically potentiate CatSper, a pH-dependent Ca(2+) channel of the sperm flagellum. We demonstrate that human CatSper is synergistically activated by elevation of intracellular pH and extracellular progesterone. Interestingly, human CatSper can be further potentiated by prostaglandins, but apparently through a binding site other than that of progesterone. Because our experimental conditions did not support second messenger signalling, CatSper or a directly associated protein serves as the elusive non-genomic progesterone receptor of sperm. Given that the CatSper-associated progesterone receptor is sperm specific and structurally different from the genomic progesterone receptor, it represents a promising target for the development of a new class of non-hormonal contraceptives.
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