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Li Q, Chen G, Yan J. Transmembrane determinants of voltage-gating differences between BK (Slo1) and Slo3 channels. Biophys J 2024; 123:2154-2166. [PMID: 38637987 DOI: 10.1016/j.bpj.2024.04.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 02/01/2024] [Accepted: 04/15/2024] [Indexed: 04/20/2024] Open
Abstract
Voltage-gated potassium channels are critical in modulating cellular excitability, with Slo (slowpoke) channels forming a unique family characterized by their large conductance and dual regulation by electrical signals and intracellular messengers. Despite their structural and evolutionary similarities, Slo1 and Slo3 channels exhibit significant differences in their voltage-gating properties. This study investigates the molecular determinants that differentiate the voltage-gating properties of human Slo1 and mouse Slo3 channels. Utilizing Slo1/Slo3 chimeras, we pinpointed the selectivity filter region as a key factor in the Slo3 channel's reduced conductance at negative voltages. The S6 transmembrane (TM) segment was identified as pivotal for the Slo3 channel's biphasic deactivation kinetics at these voltages. Additionally, the S4 and S6 TM segments were found to be responsible for the gradual slope in the Slo3 channel's conductance-voltage relationship, while multiple TM regions appear to be involved in the Slo3 channel's requirement of strong depolarization for activation. Mutations in the Slo1's S5 and S6 TM segments revealed three residues (I233, L302, and M304) that likely play a crucial role in the allosteric coupling between the voltage sensors and the pore gate.
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Affiliation(s)
- Qin Li
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; Molecular & Translational Biology and Neuroscience Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, Texas
| | - Guanxing Chen
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; Molecular & Translational Biology and Neuroscience Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, Texas
| | - Jiusheng Yan
- Department of Anesthesiology and Perioperative Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas; Molecular & Translational Biology and Neuroscience Programs, MD Anderson UT Health Graduate School of Biomedical Sciences, Houston, Texas.
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Dai P, Zou M, Cai Z, Zeng X, Zhang X, Liang M. pH Homeodynamics and Male Fertility: A Coordinated Regulation of Acid-Based Balance during Sperm Journey to Fertilization. Biomolecules 2024; 14:685. [PMID: 38927088 PMCID: PMC11201807 DOI: 10.3390/biom14060685] [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: 05/05/2024] [Revised: 06/03/2024] [Accepted: 06/10/2024] [Indexed: 06/28/2024] Open
Abstract
pH homeostasis is crucial for spermatogenesis, sperm maturation, sperm physiological function, and fertilization in mammals. HCO3- and H+ are the most significant factors involved in regulating pH homeostasis in the male reproductive system. Multiple pH-regulating transporters and ion channels localize in the testis, epididymis, and spermatozoa, such as HCO3- transporters (solute carrier family 4 and solute carrier family 26 transporters), carbonic anhydrases, and H+-transport channels and enzymes (e.g., Na+-H+ exchangers, monocarboxylate transporters, H+-ATPases, and voltage-gated proton channels). Hormone-mediated signals impose an influence on the production of some HCO3- or H+ transporters, such as NBCe1, SLC4A2, MCT4, etc. Additionally, ion channels including sperm-specific cationic channels for Ca2+ (CatSper) and K+ (SLO3) are directly or indirectly regulated by pH, exerting specific actions on spermatozoa. The slightly alkaline testicular pH is conducive to spermatogenesis, whereas the epididymis's low HCO3- concentration and acidic lumen are favorable for sperm maturation and storage. Spermatozoa pH increases substantially after being fused with seminal fluid to enhance motility. In the female reproductive tract, sperm are subjected to increasing concentrations of HCO3- in the uterine and fallopian tube, causing a rise in the intracellular pH (pHi) of spermatozoa, leading to hyperpolarization of sperm plasma membranes, capacitation, hyperactivation, acrosome reaction, and ultimately fertilization. The physiological regulation initiated by SLC26A3, SLC26A8, NHA1, sNHE, and CFTR localized in sperm is proven for certain to be involved in male fertility. This review intends to present the key factors and characteristics of pHi regulation in the testes, efferent duct, epididymis, seminal fluid, and female reproductive tract, as well as the associated mechanisms during the sperm journey to fertilization, proposing insights into outstanding subjects and future research trends.
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Affiliation(s)
| | | | | | | | - Xiaoning Zhang
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong 226019, China; (P.D.); (M.Z.); (Z.C.); (X.Z.)
| | - Min Liang
- Institute of Reproductive Medicine, Medical School, Nantong University, Nantong 226019, China; (P.D.); (M.Z.); (Z.C.); (X.Z.)
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Morabbi A, Karimian M. Trace and essential elements as vital components to improve the performance of the male reproductive system: Implications in cell signaling pathways. J Trace Elem Med Biol 2024; 83:127403. [PMID: 38340548 DOI: 10.1016/j.jtemb.2024.127403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 01/02/2024] [Accepted: 01/29/2024] [Indexed: 02/12/2024]
Abstract
Successful male fertilization requires the main processes such as normal spermatogenesis, sperm capacitation, hyperactivation, and acrosome reaction. The progress of these processes depends on some endogenous and exogenous factors. So, the optimal level of ions and essential and rare elements such as selenium, zinc, copper, iron, manganese, calcium, and so on in various types of cells of the reproductive system could affect conception and male fertility rates. The function of trace elements in the male reproductive system could be exerted through some cellular and molecular processes, such as the management of active oxygen species, involvement in the action of membrane channels, regulation of enzyme activity, regulation of gene expression and hormone levels, and modulation of signaling cascades. In this review, we aim to summarize the available evidence on the role of trace elements in improving male reproductive performance. Also, special attention is paid to the cellular aspects and the involved molecular signaling cascades.
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Affiliation(s)
- Ali Morabbi
- Department of Molecular and Cell Biology, Faculty of Basic Sciences, University of Mazandaran, Babolsar, Iran
| | - Mohammad Karimian
- Department of Molecular and Cell Biology, Faculty of Basic Sciences, University of Mazandaran, Babolsar, Iran.
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Benko F, Urminská D, Ďuračka M, Tvrdá E. Signaling Roleplay between Ion Channels during Mammalian Sperm Capacitation. Biomedicines 2023; 11:2519. [PMID: 37760960 PMCID: PMC10525812 DOI: 10.3390/biomedicines11092519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 08/31/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023] Open
Abstract
In order to accomplish their primary goal, mammalian spermatozoa must undergo a series of physiological, biochemical, and functional changes crucial for the acquisition of fertilization ability. Spermatozoa are highly polarized cells, which must swiftly respond to ionic changes on their passage through the female reproductive tract, and which are necessary for male gametes to acquire their functional competence. This review summarizes the current knowledge about specific ion channels and transporters located in the mammalian sperm plasma membrane, which are intricately involved in the initiation of changes within the ionic milieu of the sperm cell, leading to variations in the sperm membrane potential, membrane depolarization and hyperpolarization, changes in sperm motility and capacitation to further lead to the acrosome reaction and sperm-egg fusion. We also discuss the functionality of selected ion channels in male reproductive health and/or disease since these may become promising targets for clinical management of infertility in the future.
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Affiliation(s)
- Filip Benko
- Institute of Biotechnology, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 949 76 Nitra, Slovakia; (D.U.); (E.T.)
| | - Dana Urminská
- Institute of Biotechnology, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 949 76 Nitra, Slovakia; (D.U.); (E.T.)
| | - Michal Ďuračka
- AgroBioTech Research Centre, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 949 76 Nitra, Slovakia;
| | - Eva Tvrdá
- Institute of Biotechnology, Faculty of Biotechnology and Food Sciences, Slovak University of Agriculture in Nitra, Tr. A. Hlinku 2, 949 76 Nitra, Slovakia; (D.U.); (E.T.)
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Mariani NAP, Silva JV, Fardilha M, Silva EJR. Advances in non-hormonal male contraception targeting sperm motility. Hum Reprod Update 2023; 29:545-569. [PMID: 37141450 DOI: 10.1093/humupd/dmad008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Revised: 03/23/2023] [Indexed: 05/06/2023] Open
Abstract
BACKGROUND The high rates of unintended pregnancy and the ever-growing world population impose health, economic, social, and environmental threats to countries. Expanding contraceptive options, including male methods, are urgently needed to tackle these global challenges. Male contraception is limited to condoms and vasectomy, which are unsuitable for many couples. Thus, novel male contraceptive methods may reduce unintended pregnancies, meet the contraceptive needs of couples, and foster gender equality in carrying the contraceptive burden. In this regard, the spermatozoon emerges as a source of druggable targets for on-demand, non-hormonal male contraception based on disrupting sperm motility or fertilization. OBJECTIVE AND RATIONALE A better understanding of the molecules governing sperm motility can lead to innovative approaches toward safe and effective male contraceptives. This review discusses cutting-edge knowledge on sperm-specific targets for male contraception, focusing on those with crucial roles in sperm motility. We also highlight challenges and opportunities in male contraceptive drug development targeting spermatozoa. SEARCH METHODS We conducted a literature search in the PubMed database using the following keywords: 'spermatozoa', 'sperm motility', 'male contraception', and 'drug targets' in combination with other related terms to the field. Publications until January 2023 written in English were considered. OUTCOMES Efforts for developing non-hormonal strategies for male contraception resulted in the identification of candidates specifically expressed or enriched in spermatozoa, including enzymes (PP1γ2, GAPDHS, and sAC), ion channels (CatSper and KSper), transmembrane transporters (sNHE, SLC26A8, and ATP1A4), and surface proteins (EPPIN). These targets are usually located in the sperm flagellum. Their indispensable roles in sperm motility and male fertility were confirmed by genetic or immunological approaches using animal models and gene mutations associated with male infertility due to sperm defects in humans. Their druggability was demonstrated by the identification of drug-like small organic ligands displaying spermiostatic activity in preclinical trials. WIDER IMPLICATIONS A wide range of sperm-associated proteins has arisen as key regulators of sperm motility, providing compelling druggable candidates for male contraception. Nevertheless, no pharmacological agent has reached clinical developmental stages. One reason is the slow progress in translating the preclinical and drug discovery findings into a drug-like candidate adequate for clinical development. Thus, intense collaboration among academia, private sectors, governments, and regulatory agencies will be crucial to combine expertise for the development of male contraceptives targeting sperm function by (i) improving target structural characterization and the design of highly selective ligands, (ii) conducting long-term preclinical safety, efficacy, and reversibility evaluation, and (iii) establishing rigorous guidelines and endpoints for clinical trials and regulatory evaluation, thus allowing their testing in humans.
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Affiliation(s)
- Noemia A P Mariani
- Department of Biophysics and Pharmacology, Institute of Biosciences of Botucatu, São Paulo State University, Botucatu, Brazil
| | - Joana V Silva
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal
- QOPNA & LAQV, Department of Chemistry, University of Aveiro, Aveiro, Portugal
- Multidisciplinary Research in Biomedicine (UMIB), Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, Porto, Portugal
| | - Margarida Fardilha
- Department of Medical Sciences, Institute of Biomedicine (iBiMED), University of Aveiro, Aveiro, Portugal
| | - Erick J R Silva
- Department of Biophysics and Pharmacology, Institute of Biosciences of Botucatu, São Paulo State University, Botucatu, Brazil
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Lyon MD, Ferreira JJ, Li P, Bhagwat S, Butler A, Anderson K, Polo M, Santi CM. SLO3: A Conserved Regulator of Sperm Membrane Potential. Int J Mol Sci 2023; 24:11205. [PMID: 37446382 DOI: 10.3390/ijms241311205] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/03/2023] [Accepted: 07/05/2023] [Indexed: 07/15/2023] Open
Abstract
Sperm cells must undergo a complex maturation process after ejaculation to be able to fertilize an egg. One component of this maturation is hyperpolarization of the membrane potential to a more negative value. The ion channel responsible for this hyperpolarization, SLO3, was first cloned in 1998, and since then much progress has been made to determine how the channel is regulated and how its function intertwines with various signaling pathways involved in sperm maturation. Although Slo3 was originally thought to be present only in the sperm of mammals, recent evidence suggests that a primordial form of the gene is more widely expressed in some fish species. Slo3, like many reproductive genes, is rapidly evolving with low conservation between closely related species and different regulatory and pharmacological profiles. Despite these differences, SLO3 appears to have a conserved role in regulating sperm membrane potential and driving large changes in response to stimuli. The effect of this hyperpolarization of the membrane potential may vary among mammalian species just as the regulation of the channel does. Recent discoveries have elucidated the role of SLO3 in these processes in human sperm and provided tools to target the channel to affect human fertility.
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Affiliation(s)
- Maximilian D Lyon
- Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Juan J Ferreira
- Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Ping Li
- Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Shweta Bhagwat
- Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Alice Butler
- Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, MO 63110, USA
- Department of Neuroscience, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Kelsey Anderson
- Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Maria Polo
- Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, MO 63110, USA
| | - Celia M Santi
- Department of Obstetrics and Gynecology, Washington University in St. Louis, St. Louis, MO 63110, USA
- Department of Neuroscience, Washington University in St. Louis, St. Louis, MO 63110, USA
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7
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Cooray A, Kim J, Nirujan BR, Jayathilake NJ, Lee KP. Pharmacological Evidence Suggests That Slo3 Channel Is the Principal K + Channel in Boar Spermatozoa. Int J Mol Sci 2023; 24:ijms24097806. [PMID: 37175513 PMCID: PMC10178124 DOI: 10.3390/ijms24097806] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 04/20/2023] [Accepted: 04/23/2023] [Indexed: 05/15/2023] Open
Abstract
Sperm ion channels are associated with the quality and type of flagellar movement, and their differential regulation is crucial for sperm function during specific phases. The principal potassium ion channel is responsible for the majority of K+ ion flux, resulting in membrane hyperpolarization, and is essential for sperm capacitation-related signaling pathways. The molecular identity of the principal K+ channel varies greatly between different species, and there is a lack of information about boar K+ channels. We aimed to determine the channel identity of boar sperm contributing to the primary K+ current using pharmacological dissection. A series of Slo1 and Slo3 channel modulators were used for treatment. Sperm motility and related kinematic parameters were monitored using a computer-assisted sperm analysis system under non-capacitated conditions. Time-lapse flow cytometry with fluorochromes was used to measure changes in different intracellular ionic concentrations, and conventional flow cytometry was used to determine the acrosome reaction. Membrane depolarization, reduction in acrosome reaction, and motility parameters were observed upon the inhibition of the Slo3 channel, suggesting that the Slo3 gene encodes the main K+ channel in boar spermatozoa. The Slo3 channel was localized on the sperm flagellum, and the inhibition of Slo3 did not reduce sperm viability. These results may aid potential animal-model-based extrapolations and help to ameliorate motility and related parameters, leading to improved assisted reproductive methods in industrial livestock production.
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Affiliation(s)
- Akila Cooray
- Department of Physiology, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Jeongsook Kim
- Department of Physiology, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Beno Ramesh Nirujan
- Department of Physiology, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Nishani Jayanika Jayathilake
- Department of Physiology, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Republic of Korea
| | - Kyu Pil Lee
- Department of Physiology, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Republic of Korea
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Wang Y, Gao T, Shan L, Li K, Liang F, Yu J, Ni Y, Sun P. Iberiotoxin and clofilium regulate hyperactivation, acrosome reaction, and ion homeostasis synergistically during human sperm capacitation. Mol Reprod Dev 2023; 90:129-140. [PMID: 36682071 DOI: 10.1002/mrd.23671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 12/27/2022] [Accepted: 01/11/2023] [Indexed: 01/24/2023]
Abstract
Potassium channels play essential roles in the regulation of male fertility. However, potassium channels mediating K+ currents in human sperm (IKSper ) remain controversial. Besides SLO3, the SLO1 potassium channel is a potential candidate for human sperm KSper. This study intends to elucidate the function of SLO1 potassium channel during human sperm capacitation. Human sperm were treated with iberiotoxin (IbTX, a SLO1 specific inhibitor) and clofilium (SLO3 inhibitor) separately or simultaneously during in vitro capacitation. A computer-assisted sperm analyzer was used to assess sperm motility. The sperm acrosome reaction (AR) was analyzed using fluorescein isothiocyanate-conjugated Pisum sativum agglutinin staining. Sperm protein tyrosine phosphorylation was studied using western blotting. Intracellular Ca2+ , K+ , Cl- , and pH were analyzed using ion fluorescence probes. Independent inhibition with IbTX or clofilium decreased the sperm hyperactivation, AR, and protein tyrosine phosphorylation, and was accompanied by an increase in [K+ ]i , [Cl- ]i , and pHi , but a decrease in [Ca2+ ]i . Simultaneously inhibition with IbTX and clofilium lower sperm hyperactivation and AR more than independent inhibition. The increase in [K+ ]i , [Cl- ]i , and pHi , and the decrease in [Ca2+ ]i were more pronounced. This study suggested that the SLO1 potassium channel may have synergic roles with SLO3 during human sperm capacitation.
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Affiliation(s)
- Yayan Wang
- School of Pharmacy, Hangzhou Medical College, Hangzhou, Zhejiang, China
- Department of Gynecology and Obstetrics, Lishui People's Hospital, Lishui, Zhejiang, China
| | - Tian Gao
- School of Pharmacy, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Lijun Shan
- School of Pharmacy, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Kun Li
- School of Pharmacy, Hangzhou Medical College, Hangzhou, Zhejiang, China
- Zhejiang Provincial Laboratory of Experimental Animal's & Nonclinical Laboratory Studies, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Fei Liang
- School of Pharmacy, Hangzhou Medical College, Hangzhou, Zhejiang, China
- Zhejiang Provincial Laboratory of Experimental Animal's & Nonclinical Laboratory Studies, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Jianmin Yu
- School of Pharmacy, Hangzhou Medical College, Hangzhou, Zhejiang, China
- Zhejiang Provincial Laboratory of Experimental Animal's & Nonclinical Laboratory Studies, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Ya Ni
- School of Pharmacy, Hangzhou Medical College, Hangzhou, Zhejiang, China
- Zhejiang Provincial Laboratory of Experimental Animal's & Nonclinical Laboratory Studies, Hangzhou Medical College, Hangzhou, Zhejiang, China
| | - Peibei Sun
- School of Pharmacy, Hangzhou Medical College, Hangzhou, Zhejiang, China
- Zhejiang Provincial Laboratory of Experimental Animal's & Nonclinical Laboratory Studies, Hangzhou Medical College, Hangzhou, Zhejiang, China
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Gonzalez-Perez V, Zhou Y, Ciorba MA, Lingle CJ. The LRRC family of BK channel regulatory subunits: potential roles in health and disease. J Physiol 2022; 600:1357-1371. [PMID: 35014034 PMCID: PMC8930516 DOI: 10.1113/jp281952] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 01/04/2022] [Indexed: 11/08/2022] Open
Abstract
Large conductance K+ channels, termed BK channels, regulate a variety of cellular and physiological functions. Although universally activated by changes in voltage or [Ca2+ ]i , the threshold for BK channel activation varies among loci of expression, often arising from cell-specific regulatory subunits including a family of leucine rich repeat-containing (LRRC) γ subunits (LRRC26, LRRC52, LRRC55 and LRRC38). The 'founding' member of this family, LRRC26, was originally identified as a tumour suppressor in various cancers. An LRRC26 knockout (KO) mouse model recently revealed that LRRC26 is also highly expressed in secretory epithelial cells and partners with BK channels in the salivary gland and colonic goblet cells to promote sustained K+ fluxes likely essential for normal secretory function. To accomplish this, LRRC26 negatively shifts the range of BK channel activation such that channels contribute to K+ flux near typical epithelial cell resting conditions. In colon, the absence of LRRC26 increases vulnerability to colitis. LRRC26-containing BK channels are also likely important regulators of epithelial function in other loci, including airways, female reproductive tract and mammary gland. Based on an LRRC52 KO mouse model, LRRC52 regulation of large conductance K+ channels plays a role both in sperm function and in cochlear inner hair cells. Although our understanding of LRRC-containing BK channels remains rudimentary, KO mouse models may help define other organs in which LRRC-containing channels support normal function. A key topic for future work concerns identification of endogenous mechanisms, whether post-translational or via gene regulation, that may impact LRRC-dependent pathologies.
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Affiliation(s)
- Vivian Gonzalez-Perez
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave., Saint Louis, MO 63110 USA
| | - Yu Zhou
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave., Saint Louis, MO 63110 USA
| | - Matthew A. Ciorba
- Department of Internal Medicine, Division of Gastroenterology, Washington University School of Medicine, St. Louis MO 63110 USA
| | - Christopher J. Lingle
- Department of Anesthesiology, Washington University School of Medicine, 660 S. Euclid Ave., Saint Louis, MO 63110 USA
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10
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Lv M, Liu C, Ma C, Yu H, Shao Z, Gao Y, Liu Y, Wu H, Tang D, Tan Q, Zhang J, Li K, Xu C, Geng H, Zhang J, Li H, Mao X, Ge L, Fu F, Zhong K, Xu Y, Tao F, Zhou P, Wei Z, He X, Zhang F, Cao Y. Homozygous mutation in SLO3 leads to severe asthenoteratozoospermia due to acrosome hypoplasia and mitochondrial sheath malformations. Reprod Biol Endocrinol 2022; 20:5. [PMID: 34980136 PMCID: PMC8722334 DOI: 10.1186/s12958-021-00880-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 12/10/2021] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND Potassium channels are important for the structure and function of the spermatozoa. As a potassium transporter, the mSlo3 is essential for male fertility as Slo3 knockout male mice were infertile with the series of functional defects in sperm cells. However, no pathogenic variant has been detected in human SLO3 to date. Here we reported a human case with homozygous SLO3 mutation. The function of SLO3 in human sperm and the corresponding assisted reproductive strategy are also investigated. METHODS We performed whole-exome sequencing analysis from a large cohort of 105 patients with asthenoteratozoospermia. The effects of the variant were investigated by quantitative RT-PCR, western blotting, and immunofluorescence assays using the patient spermatozoa. Sperm morphological and ultrastructural studies were conducted using haematoxylin and eosin staining, scanning and transmission electron microscopy. RESULTS We identified a homozygous missense variant (c.1237A > T: p.Ile413Phe) in the sperm-specific SLO3 in one Chinese patient with male infertility. This SLO3 variant was rare in human control populations and predicted to be deleterious by multiple bioinformatic tools. Sperm from the individual harbouring the homozygous SLO3 variant exhibited severe morphological abnormalities, such as acrosome hypoplasia, disruption of the mitochondrial sheath, coiled tails, and motility defects. The levels of SLO3 mRNA and protein in spermatozoa from the affected individual were reduced. Furthermore, the acrosome reaction, mitochondrial membrane potential, and membrane potential during capacitation were also afflicted. The levels of acrosome marker glycoproteins and PLCζ1 as well as the mitochondrial sheath protein HSP60 and SLO3 auxiliary subunit LRRC52, were significantly reduced in the spermatozoa from the affected individual. The affected man was sterile due to acrosome and mitochondrial dysfunction; however, intra-cytoplasmic sperm injection successfully rescued this infertile condition. CONCLUSIONS SLO3 deficiency seriously impact acrosome formation, mitochondrial sheath assembly, and the function of K+ channels. Our findings provided clinical implications for the genetic and reproductive counselling of affected families.
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Affiliation(s)
- Mingrong Lv
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Chunyu Liu
- Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai, 200011, China
- Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Shanghai, 200011, China
- NHC Key Laboratory of Reproduction Regulation, Shanghai Institute for Biomedical and Pharmaceutical Technologies, Fudan University, Shanghai, 200011, China
| | - Chunjie Ma
- NHC Key Laboratory of Male Reproduction and Genetics, Guangdong Provincial Reproductive Science Institute (Guangdong Provincial Fertility Hospital), Guangzhou, 510600, China
| | - Hui Yu
- Department of Obstetrics and Gynecology, Fuyang Hospital of Anhui Medical University, Fuyang, China
| | - Zhongmei Shao
- Department of Obstetrics and Gynecology, Fuyang Hospital of Anhui Medical University, Fuyang, China
| | - Yang Gao
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
- Anhui Province Key Laboratory of Reproductive Health and Genetics, Anhui Medical University, Hefei, China
| | - Yiyuan Liu
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Huan Wu
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Dongdong Tang
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Qing Tan
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- Anhui Provincial Human Sperm Bank, the First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Junqiang Zhang
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
- Anhui Province Key Laboratory of Reproductive Health and Genetics, Anhui Medical University, Hefei, China
| | - Kuokuo Li
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Anhui Province Key Laboratory of Reproductive Health and Genetics, Anhui Medical University, Hefei, China
| | - Chuan Xu
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Hao Geng
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Jingjing Zhang
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Hang Li
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- Anhui Provincial Human Sperm Bank, the First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Xiaohong Mao
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- Anhui Provincial Human Sperm Bank, the First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Lei Ge
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- Anhui Provincial Human Sperm Bank, the First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Feifei Fu
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- Anhui Provincial Human Sperm Bank, the First Affiliated Hospital of Anhui Medical University, Hefei, China
| | - Kaixin Zhong
- NHC Key Laboratory of Male Reproduction and Genetics, Guangdong Provincial Reproductive Science Institute (Guangdong Provincial Fertility Hospital), Guangzhou, 510600, China
| | - Yuping Xu
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Fangbiao Tao
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Ping Zhou
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Zhaolian Wei
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China
| | - Xiaojin He
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China.
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China.
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China.
- Anhui Provincial Human Sperm Bank, the First Affiliated Hospital of Anhui Medical University, Hefei, China.
| | - Feng Zhang
- Obstetrics and Gynecology Hospital, State Key Laboratory of Genetic Engineering at School of Life Sciences, Institute of Reproduction and Development, Fudan University, Shanghai, 200011, China.
- Shanghai Key Laboratory of Female Reproductive Endocrine Related Diseases, Shanghai, 200011, China.
- NHC Key Laboratory of Reproduction Regulation, Shanghai Institute for Biomedical and Pharmaceutical Technologies, Fudan University, Shanghai, 200011, China.
| | - Yunxia Cao
- Reproductive Medicine Center, Department of Obstetrics and Gynecology, the First Affiliated Hospital of Anhui Medical University, Hefei, 230022, Anhui, China.
- NHC Key Laboratory of Study on Abnormal Gametes and Reproductive Tract (Anhui Medical University), Hefei, 230032, Anhui, China.
- Key Laboratory of Population Health Across Life Cycle, Anhui Medical University, Ministry of Education of the People's Republic of China, Hefei, 230032, China.
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11
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Aldana A, Carneiro J, Martínez-Mekler G, Darszon A. Discrete Dynamic Model of the Mammalian Sperm Acrosome Reaction: The Influence of Acrosomal pH and Physiological Heterogeneity. Front Physiol 2021; 12:682790. [PMID: 34349664 PMCID: PMC8328089 DOI: 10.3389/fphys.2021.682790] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 05/28/2021] [Indexed: 01/31/2023] Open
Abstract
The acrosome reaction (AR) is an exocytotic process essential for mammalian fertilization. It involves diverse physiological changes (biochemical, biophysical, and morphological) that culminate in the release of the acrosomal content to the extracellular medium as well as a reorganization of the plasma membrane (PM) that allows sperm to interact and fuse with the egg. In spite of many efforts, there are still important pending questions regarding the molecular mechanism regulating the AR. Particularly, the contribution of acrosomal alkalinization to AR triggering physiological conditions is not well understood. Also, the dependence of the proportion of sperm capable of undergoing AR on the physiological heterogeneity within a sperm population has not been studied. Here, we present a discrete mathematical model for the human sperm AR based on the physiological interactions among some of the main components of this complex exocytotic process. We show that this model can qualitatively reproduce diverse experimental results, and that it can be used to analyze how acrosomal pH (pH a ) and cell heterogeneity regulate AR. Our results confirm that a pH a increase can on its own trigger AR in a subpopulation of sperm, and furthermore, it indicates that this is a necessary step to trigger acrosomal exocytosis through progesterone, a known natural inducer of AR. Most importantly, we show that the proportion of sperm undergoing AR is directly related to the detailed structure of the population physiological heterogeneity.
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Affiliation(s)
- Andrés Aldana
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Jorge Carneiro
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
- Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova, Oeiras, Portugal
| | - Gustavo Martínez-Mekler
- Centro de Ciencias de la Complejidad, Universidad Nacional Autónoma de México, Mexico City, Mexico
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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12
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Nowicka-Bauer K, Szymczak-Cendlak M. Structure and Function of Ion Channels Regulating Sperm Motility-An Overview. Int J Mol Sci 2021; 22:ijms22063259. [PMID: 33806823 PMCID: PMC8004680 DOI: 10.3390/ijms22063259] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 03/18/2021] [Accepted: 03/19/2021] [Indexed: 12/18/2022] Open
Abstract
Sperm motility is linked to the activation of signaling pathways that trigger movement. These pathways are mainly dependent on Ca2+, which acts as a secondary messenger. The maintenance of adequate Ca2+ concentrations is possible thanks to proper concentrations of other ions, such as K+ and Na+, among others, that modulate plasma membrane potential and the intracellular pH. Like in every cell, ion homeostasis in spermatozoa is ensured by a vast spectrum of ion channels supported by the work of ion pumps and transporters. To achieve success in fertilization, sperm ion channels have to be sensitive to various external and internal factors. This sensitivity is provided by specific channel structures. In addition, novel sperm-specific channels or isoforms have been found with compositions that increase the chance of fertilization. Notably, the most significant sperm ion channel is the cation channel of sperm (CatSper), which is a sperm-specific Ca2+ channel required for the hyperactivation of sperm motility. The role of other ion channels in the spermatozoa, such as voltage-gated Ca2+ channels (VGCCs), Ca2+-activated Cl-channels (CaCCs), SLO K+ channels or voltage-gated H+ channels (VGHCs), is to ensure the activation and modulation of CatSper. As the activation of sperm motility differs among metazoa, different ion channels may participate; however, knowledge regarding these channels is still scarce. In the present review, the roles and structures of the most important known ion channels are described in regard to regulation of sperm motility in animals.
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Affiliation(s)
- Karolina Nowicka-Bauer
- Department of Chemical Physics, Faculty of Chemistry, Adam Mickiewicz University in Poznań, 61-614 Poznan, Poland
- Correspondence:
| | - Monika Szymczak-Cendlak
- Department of Animal Physiology and Development, Faculty of Biology, Adam Mickiewicz University in Poznań, 61-614 Poznan, Poland;
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13
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Kang H, Liu M, Zhang W, Huang RZ, Zhao N, Chen C, Zeng XH. Na +/H + Exchangers Involve in Regulating the pH-Sensitive Ion Channels in Mouse Sperm. Int J Mol Sci 2021; 22:ijms22041612. [PMID: 33562644 PMCID: PMC7914462 DOI: 10.3390/ijms22041612] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 12/20/2022] Open
Abstract
Sperm-specific K+ ion channel (KSper) and Ca2+ ion channel (CatSper), whose elimination causes male infertility in mice, determine the membrane potential and Ca2+ influx, respectively. KSper and CatSper can be activated by cytosolic alkalization, which occurs during sperm going through the alkaline environment of the female reproductive tract. However, which intracellular pH (pHi) regulator functionally couples to the activation of KSper/CatSper remains obscure. Although Na+/H+ exchangers (NHEs) have been implicated to mediate pHi in sperm, there is a lack of direct evidence confirming the functional coupling between NHEs and KSper/CatSper. Here, 5-(N,N-dimethyl)-amiloride (DMA), an NHEs inhibitor that firstly proved not to affect KSper/CatSper directly, was chosen to examine NHEs function on KSper/CatSper in mouse sperm. The results of patch clamping recordings showed that, when extracellular pH was at the physiological level of 7.4, DMA application caused KSper inhibition and the depolarization of membrane potential when pipette solutions were not pH-buffered. In contrast, these effects were minimized when pipette solutions were pH-buffered, indicating that they solely resulted from pHi acidification caused by NHEs inhibition. Similarly, DMA treatment reduced CatSper current and intracellular Ca2+, effects also dependent on the buffer capacity of pH in pipette solutions. The impairment of sperm motility was also observed after DMA incubation. These results manifested that NHEs activity is coupled to the activation of KSper/CatSper under physiological conditions.
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Affiliation(s)
- Hang Kang
- Institute of Life Science and School of Life Science, Nanchang University, Nanchang 330031, Jiangxi, China; (H.K.); (M.L.); (W.Z.); (N.Z.)
| | - Min Liu
- Institute of Life Science and School of Life Science, Nanchang University, Nanchang 330031, Jiangxi, China; (H.K.); (M.L.); (W.Z.); (N.Z.)
| | - Wei Zhang
- Institute of Life Science and School of Life Science, Nanchang University, Nanchang 330031, Jiangxi, China; (H.K.); (M.L.); (W.Z.); (N.Z.)
| | - Rong-Zu Huang
- Institute of Reproductive Medicine, School of Medicine, Nantong University, Nantong 226019, Jiangsu, China; (R.-Z.H.); (C.C.)
| | - Na Zhao
- Institute of Life Science and School of Life Science, Nanchang University, Nanchang 330031, Jiangxi, China; (H.K.); (M.L.); (W.Z.); (N.Z.)
| | - Chen Chen
- Institute of Reproductive Medicine, School of Medicine, Nantong University, Nantong 226019, Jiangsu, China; (R.-Z.H.); (C.C.)
| | - Xu-Hui Zeng
- Institute of Reproductive Medicine, School of Medicine, Nantong University, Nantong 226019, Jiangsu, China; (R.-Z.H.); (C.C.)
- Correspondence: ; Tel.: +86-177-6196-0066
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14
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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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15
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Wang GM, Zhong ZG, Du XR, Zhang FF, Guo Q, Liu Y, Tang QY, Zhang Z. Cloning and characterization of the rat Slo3 (K Ca 5.1) channel: From biophysics to pharmacology. Br J Pharmacol 2020; 177:3552-3567. [PMID: 32335912 DOI: 10.1111/bph.15078] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 04/02/2020] [Accepted: 04/03/2020] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND AND PURPOSE The Slo3 potassium (KCa 5.1) channel, which is specifically expressed in the testis and sperm, is essential for mammalian male fertilization. The sequence divergence of the bovine, mouse and human Slo3 α-subunit revealed a rapid evolution rate across different species. The rat Slo3 (rSlo3) channel has not been cloned and characterized previously. EXPERIMENTAL APPROACH We used molecular cloning, electrophysiology (inside-out patches and outside-out patches) and mutagenesis to investigate the biophysical properties and pharmacological characteristics of the rSlo3 channel. KEY RESULTS The rat Slo3 channel (rSlo3) is gated by voltage and cytosolic pH rather than intracellular calcium. The characteristics of voltage-dependent, pH-sensitivity and activation kinetics of the rSlo3 channel differ from the characteristics of other Slo3 orthologues. In terms of pharmacology, the 4-AP blockade of the rSlo3 channel also shows properties distinct from its blockade of the mSlo3 channel. Iberiotoxin and progesterone weakly inhibit the rSlo3 channel. Finally, we found that propofol, one of the widely used general anaesthetics, blocks the rSlo3 channel from both intracellular and extracellular sides, whereas ketamine only blocks the rSlo3 channel at the extracellular side. CONCLUSION AND IMPLICATIONS Our findings suggest that the rSlo3 channel possesses unique biophysical and pharmacological properties. Our results provide new insights into the diversities of the Slo3 family of channels, which are valuable for estimating the effects of the use of these drugs to improve sperm quality.
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Affiliation(s)
- Guang-Ming Wang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Jiangsu Province Key Laboratory of Anaesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
| | - Zhi-Gang Zhong
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Jiangsu Province Key Laboratory of Anaesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
| | - Xiang-Rong Du
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Jiangsu Province Key Laboratory of Anaesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
| | - Fei-Fei Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Jiangsu Province Key Laboratory of Anaesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
| | - Qing Guo
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Jiangsu Province Key Laboratory of Anaesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
| | - Ye Liu
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Jiangsu Province Key Laboratory of Anaesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
| | - Qiong-Yao Tang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Jiangsu Province Key Laboratory of Anaesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
| | - Zhe Zhang
- Jiangsu Province Key Laboratory of Anesthesiology, Xuzhou Medical University, Xuzhou, China.,Jiangsu Province Key Laboratory of Anaesthesia and Analgesia Application Technology, Xuzhou Medical University, Xuzhou, China
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16
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Teixeira-Duarte CM, Fonseca F, Morais-Cabral JH. Activation of a nucleotide-dependent RCK domain requires binding of a cation cofactor to a conserved site. eLife 2019; 8:50661. [PMID: 31868587 PMCID: PMC6957272 DOI: 10.7554/elife.50661] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Accepted: 12/22/2019] [Indexed: 12/24/2022] Open
Abstract
RCK domains regulate the activity of K+ channels and transporters in eukaryotic and prokaryotic organisms by responding to ions or nucleotides. The mechanisms of RCK activation by Ca2+ in the eukaryotic BK and bacterial MthK K+ channels are well understood. However, the molecular details of activation in nucleotide-dependent RCK domains are not clear. Through a functional and structural analysis of the mechanism of ATP activation in KtrA, a RCK domain from the B. subtilis KtrAB cation channel, we have found that activation by nucleotide requires binding of cations to an intra-dimer interface site in the RCK dimer. In particular, divalent cations are coordinated by the γ-phosphates of bound-ATP, tethering the two subunits and stabilizing the active state conformation. Strikingly, the binding site residues are highly conserved in many different nucleotide-dependent RCK domains, indicating that divalent cations are a general cofactor in the regulatory mechanism of many nucleotide-dependent RCK domains.
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Affiliation(s)
- Celso M Teixeira-Duarte
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal.,Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, Porto, Portugal
| | - Fátima Fonseca
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
| | - João H Morais-Cabral
- Instituto de Investigação e Inovação em Saúde (i3S), Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular (IBMC), Universidade do Porto, Porto, Portugal
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17
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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 2019; 25:758-776. [PMID: 31665287 PMCID: PMC6847974 DOI: 10.1093/humupd/dmz032] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [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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18
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A cytoplasmic Slo3 isoform is expressed in somatic tissues. Mol Biol Rep 2019; 46:5561-5567. [PMID: 31270758 DOI: 10.1007/s11033-019-04943-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 06/26/2019] [Indexed: 12/19/2022]
Abstract
Slo3 is a pH-sensitive and weakly voltage-sensitive potassium channel that is essential for male fertility in mouse and whose expression is regarded as sperm-specific. These properties have proposed Slo3 as a candidate target for male contraceptive drugs. Nonetheless, the tissue distribution of Slo3 expression has not been rigorously studied yet. Applying computational and RT-PCR approaches, we identified expression of two short Slo3 isoforms in somatic mouse tissues such as brain, kidney and eye. These isoforms, which seem to result of transcription starting sites between exons 20 and 21, have an identical open reading frame, both encoding the terminal 381 amino acids of the cytosolic Slo3 domain. We corroborated the expression of these isoforms in mouse brain and testis by Western-blot. The complete isoform encoding the Slo3 ion channel was uniquely detected in testis, both at transcript and protein level. Although the functional role of the cytosolic Slo3 isoforms remains to be established, we propose that they may have a functional effect by modulating Slo channels trafficking and/or activity. This study confirms that expression of full-length Slo3 is sperm-specific but warns against developing contraceptive drugs targeting the C-terminal tail of Slo3 channels.
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19
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Regulatory γ1 subunits defy symmetry in functional modulation of BK channels. Proc Natl Acad Sci U S A 2018; 115:9923-9928. [PMID: 30224470 DOI: 10.1073/pnas.1804560115] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Structural symmetry is a hallmark of homomeric ion channels. Nonobligatory regulatory proteins can also critically define the precise functional role of such channels. For instance, the pore-forming subunit of the large conductance voltage and calcium-activated potassium (BK, Slo1, or KCa1.1) channels encoded by a single KCa1.1 gene assembles in a fourfold symmetric fashion. Functional diversity arises from two families of regulatory subunits, β and γ, which help define the range of voltages over which BK channels in a given cell are activated, thereby defining physiological roles. A BK channel can contain zero to four β subunits per channel, with each β subunit incrementally influencing channel gating behavior, consistent with symmetry expectations. In contrast, a γ1 subunit (or single type of γ1 subunit complex) produces a functionally all-or-none effect, but the underlying stoichiometry of γ1 assembly and function remains unknown. Here we utilize two distinct and independent methods, a Forster resonance energy transfer-based optical approach and a functional reporter in single-channel recordings, to reveal that a BK channel can contain up to four γ1 subunits, but a single γ1 subunit suffices to induce the full gating shift. This requires that the asymmetric association of a single regulatory protein can act in a highly concerted fashion to allosterically influence conformational equilibria in an otherwise symmetric K+ channel.
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BK Channels Mediate Synaptic Plasticity Underlying Habituation in Rats. J Neurosci 2017; 37:4540-4551. [PMID: 28348135 DOI: 10.1523/jneurosci.3699-16.2017] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 03/17/2017] [Accepted: 03/21/2017] [Indexed: 11/21/2022] Open
Abstract
Habituation is a basic form of implicit learning and represents a sensory filter that is disrupted in autism, schizophrenia, and several other mental disorders. Despite extensive research in the past decades on habituation of startle and other escape responses, the underlying neural mechanisms are still not fully understood. There is evidence from previous studies indicating that BK channels might play a critical role in habituation. We here used a wide array of approaches to test this hypothesis. We show that BK channel activation and subsequent phosphorylation of these channels are essential for synaptic depression presumably underlying startle habituation in rats, using patch-clamp recordings and voltage-sensitive dye imaging in slices. Furthermore, positive modulation of BK channels in vivo can enhance short-term habituation. Although results using different approaches do not always perfectly align, together they provide convincing evidence for a crucial role of BK channel phosphorylation in synaptic depression underlying short-term habituation of startle. We also show that this mechanism can be targeted to enhance short-term habituation and therefore to potentially ameliorate sensory filtering deficits associated with psychiatric disorders.SIGNIFICANCE STATEMENT Short-term habituation is the most fundamental form of implicit learning. Habituation also represents a filter for inundating sensory information, which is disrupted in autism, schizophrenia, and other psychiatric disorders. Habituation has been studied in different organisms and behavioral models and is thought to be caused by synaptic depression in respective pathways. The underlying molecular mechanisms, however, are poorly understood. We here identify, for the first time, a BK channel-dependent molecular synaptic mechanism leading to synaptic depression that is crucial for habituation, and we discuss the significance of our findings for potential treatments enhancing habituation.
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Kaczmarek LK, Aldrich RW, Chandy KG, Grissmer S, Wei AD, Wulff H. International Union of Basic and Clinical Pharmacology. C. Nomenclature and Properties of Calcium-Activated and Sodium-Activated Potassium Channels. Pharmacol Rev 2017; 69:1-11. [PMID: 28267675 PMCID: PMC11060434 DOI: 10.1124/pr.116.012864] [Citation(s) in RCA: 65] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/02/2024] Open
Abstract
A subset of potassium channels is regulated primarily by changes in the cytoplasmic concentration of ions, including calcium, sodium, chloride, and protons. The eight members of this subfamily were originally all designated as calcium-activated channels. More recent studies have clarified the gating mechanisms for these channels and have documented that not all members are sensitive to calcium. This article describes the molecular relationships between these channels and provides an introduction to their functional properties. It also introduces a new nomenclature that differentiates between calcium- and sodium-activated potassium channels.
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Affiliation(s)
- Leonard K Kaczmarek
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Richard W Aldrich
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - K George Chandy
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Stephan Grissmer
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Aguan D Wei
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
| | - Heike Wulff
- Departments of Pharmacology and Cellular and Molecular Physiology, Yale School of Medicine, New Haven, Connecticut (L.K.K.); Center for Learning and Memory and Department of Neuroscience, University of Texas at Austin, Austin, Texas (R.W.A.); Laboratory of Molecular Physiology in the Infection and Immunity Theme, Lee Kong Chian School of Medicine, Nanyang Technological University, Singapore (K.G.C.); Institute of Applied Physiology, Ulm University, Ulm, Germany (S.G.); Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington (A.D.W.); and Department of Pharmacology, School of Medicine, University of California, Davis, California (H.W.)
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Kaupp UB, Strünker T. Signaling in Sperm: More Different than Similar. Trends Cell Biol 2016; 27:101-109. [PMID: 27825709 DOI: 10.1016/j.tcb.2016.10.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 10/13/2016] [Accepted: 10/14/2016] [Indexed: 11/30/2022]
Abstract
For a given sensory cell type, signaling motifs are rather uniform across phyla. By contrast, sperm from different species use diverse repertoires of sperm-specific signaling molecules and even closely related protein isoforms feature different properties and serve different functions. This surprising diversity has consequences for strategies in fertilization research and it will take some time to get the big picture. We discuss the function of receptors, ion channels, and exchangers embedded in cellular pathways from different sperm species.
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Affiliation(s)
- U B Kaupp
- Center of Advanced European Studies and Research (CAESAR), Department of Molecular Sensory Systems, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany.
| | - T Strünker
- University Hospital Münster, Center of Reproductive Medicine and Andrology, Albert-Schweitzer-Campus 1, Geb. D11, 48149 Münster, Germany
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Fechner S, Alvarez L, Bönigk W, Müller A, Berger TK, Pascal R, Trötschel C, Poetsch A, Stölting G, Siegfried KR, Kremmer E, Seifert R, Kaupp UB. A K(+)-selective CNG channel orchestrates Ca(2+) signalling in zebrafish sperm. eLife 2015; 4:e07624. [PMID: 26650356 PMCID: PMC4749565 DOI: 10.7554/elife.07624] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2015] [Accepted: 12/09/2015] [Indexed: 01/03/2023] Open
Abstract
Calcium in the flagellum controls sperm navigation. In sperm of marine invertebrates and mammals, Ca(2+) signalling has been intensely studied, whereas for fish little is known. In sea urchin sperm, a cyclic nucleotide-gated K(+) channel (CNGK) mediates a cGMP-induced hyperpolarization that evokes Ca(2+) influx. Here, we identify in sperm of the freshwater fish Danio rerio a novel CNGK family member featuring non-canonical properties. It is located in the sperm head rather than the flagellum and is controlled by intracellular pH, but not cyclic nucleotides. Alkalization hyperpolarizes sperm and produces Ca(2+) entry. Ca(2+) induces spinning-like swimming, different from swimming of sperm from other species. The "spinning" mode probably guides sperm into the micropyle, a narrow entrance on the surface of fish eggs. A picture is emerging of sperm channel orthologues that employ different activation mechanisms and serve different functions. The channel inventories probably reflect adaptations to species-specific challenges during fertilization.
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Affiliation(s)
- Sylvia Fechner
- Abteilung Molekulare Neurosensorik, Center of Advanced European Studies and Research, Bonn, Germany
| | - Luis Alvarez
- Abteilung Molekulare Neurosensorik, Center of Advanced European Studies and Research, Bonn, Germany
| | - Wolfgang Bönigk
- Abteilung Molekulare Neurosensorik, Center of Advanced European Studies and Research, Bonn, Germany
| | - Astrid Müller
- Abteilung Molekulare Neurosensorik, Center of Advanced European Studies and Research, Bonn, Germany
| | - Thomas K Berger
- Abteilung Molekulare Neurosensorik, Center of Advanced European Studies and Research, Bonn, Germany
| | - Rene Pascal
- Abteilung Molekulare Neurosensorik, Center of Advanced European Studies and Research, Bonn, Germany
| | | | - Ansgar Poetsch
- Lehrstuhl Biochemie der Pflanzen, Ruhr-Universität Bochum, Bochum, Germany
| | - Gabriel Stölting
- Institute of Complex Systems 4, Forschungszentrum Jülich, Jülich, Germany
| | - Kellee R Siegfried
- Biology Department, University of Massachusetts Boston, Boston, United States
| | - Elisabeth Kremmer
- Institut für Molekulare Immunologie, Helmholtz-Zentrum München, München, Germany
| | - Reinhard Seifert
- Abteilung Molekulare Neurosensorik, Center of Advanced European Studies and Research, Bonn, Germany
| | - U Benjamin Kaupp
- Abteilung Molekulare Neurosensorik, Center of Advanced European Studies and Research, Bonn, Germany
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24
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Cryo-electron microscopy structure of the Slo2.2 Na(+)-activated K(+) channel. Nature 2015; 527:198-203. [PMID: 26436452 PMCID: PMC4886347 DOI: 10.1038/nature14958] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/15/2015] [Indexed: 12/26/2022]
Abstract
Na+-activated K+ channels are members of the Slo family of large conductance K+ channels that are widely expressed in the brain, where their opening regulates neuronal excitability. These channels are fascinating for the biological roles they fulfill as well as for their intriguing biophysical properties, including conductance levels ten times most other K+ channels and gating sensitivity to intracellular Na+. Here we present the structure a complete Na+-activated K+ channel, Slo2.2, in the Na+-free state, determined by cryo-electron microscopy at a nominal resolution of 4.5 Å. The channel is composed of a large cytoplasmic gating ring within which resides the Na+-binding site and a transmembrane domain that closely resembles voltage-gated K+ channels. In the structure, the cytoplasmic domain adopts a closed conformation and the ion conduction pore is also closed. The structure provides a first view of a member of the Slo K+ channel family, which reveals features explaining their high conductance and gating mechanism.
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25
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Wrighton DC, Muench SP, Lippiat JD. Mechanism of inhibition of mouse Slo3 (KCa 5.1) potassium channels by quinine, quinidine and barium. Br J Pharmacol 2015; 172:4355-63. [PMID: 26045093 PMCID: PMC4556473 DOI: 10.1111/bph.13214] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 05/13/2015] [Accepted: 05/26/2015] [Indexed: 12/21/2022] Open
Abstract
Background and Purpose The Slo3 (KCa5.1) channel is a major component of mammalian KSper (sperm potassium conductance) channels and inhibition of these channels by quinine and barium alters sperm motility. The aim of this investigation was to determine the mechanism by which these drugs inhibit Slo3 channels. Experimental Approach Mouse (m) Slo3 (KCa5.1) channels or mutant forms were expressed in Xenopus oocytes and currents recorded with 2-electrode voltage-clamp. Gain-of-function mSlo3 mutations were used to explore the state-dependence of the inhibition. The interaction between quinidine and mSlo3 channels was modelled by in silico docking. Key Results Several drugs known to block KSper also affected mSlo3 channels with similar levels of inhibition. The inhibition induced by extracellular barium was prevented by increasing the extracellular potassium concentration. R196Q and F304Y mutations in the mSlo3 voltage sensor and pore, respectively, both increased channel activity. The F304Y mutation did not alter the effects of barium, but increased the potency of inhibition by both quinine and quinidine approximately 10-fold; this effect was not observed with the R196Q mutation. Conclusions and Implications Block of mSlo3 channels by quinine, quinidine and barium is not state-dependent. Barium inhibits mSlo3 outside the cell by interacting with the selectivity filter, whereas quinine and quinidine act from the inside, by binding in a hydrophobic pocket formed by the S6 segment of each subunit. Furthermore, we propose that the Slo3 channel activation gate lies deep within the pore between F304 in the S6 segment and the selectivity filter.
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Affiliation(s)
- David C Wrighton
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Stephen P Muench
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Jonathan D Lippiat
- School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds, UK
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26
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Miller MR, Mansell SA, Meyers SA, Lishko PV. Flagellar ion channels of sperm: similarities and differences between species. Cell Calcium 2015; 58:105-13. [DOI: 10.1016/j.ceca.2014.10.009] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Revised: 10/16/2014] [Accepted: 10/20/2014] [Indexed: 10/24/2022]
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27
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SLO3 auxiliary subunit LRRC52 controls gating of sperm KSPER currents and is critical for normal fertility. Proc Natl Acad Sci U S A 2015; 112:2599-604. [PMID: 25675513 DOI: 10.1073/pnas.1423869112] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Following entry into the female reproductive tract, mammalian sperm undergo a maturation process termed capacitation that results in competence to fertilize ova. Associated with capacitation is an increase in membrane conductance to both Ca(2+) and K(+), leading to an elevation in cytosolic Ca(2+) critical for activation of hyperactivated swimming motility. In mice, the Ca(2+) conductance (alkalization-activated Ca(2+)-permeable sperm channel, CATSPER) arises from an ensemble of CATSPER subunits, whereas the K(+) conductance (sperm pH-regulated K(+) current, KSPER) arises from a pore-forming ion channel subunit encoded by the slo3 gene (SLO3) subunit. In the mouse, both CATSPER and KSPER are activated by cytosolic alkalization and a concerted activation of CATSPER and KSPER is likely a common facet of capacitation-associated increases in Ca(2+) and K(+) conductance among various mammalian species. The properties of heterologously expressed mouse SLO3 channels differ from native mouse KSPER current. Recently, a potential KSPER auxiliary subunit, leucine-rich-repeat-containing protein 52 (LRRC52), was identified in mouse sperm and shown to shift gating of SLO3 to be more equivalent to native KSPER. Here, we show that genetic KO of LRRC52 results in mice with severely impaired fertility. Activation of KSPER current in sperm lacking LRRC52 requires more positive voltages and higher pH than for WT KSPER. These results establish a critical role of LRRC52 in KSPER channels and demonstrate that loss of a non-pore-forming auxiliary subunit results in severe fertility impairment. Furthermore, through analysis of several genotypes that influence KSPER current properties we show that in vitro fertilization competence correlates with the net KSPER conductance available for activation under physiological conditions.
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Brenker C, Zhou Y, Müller A, Echeverry FA, Trötschel C, Poetsch A, Xia XM, Bönigk W, Lingle CJ, Kaupp UB, Strünker T. The Ca2+-activated K+ current of human sperm is mediated by Slo3. eLife 2014; 3:e01438. [PMID: 24670955 PMCID: PMC3966514 DOI: 10.7554/elife.01438] [Citation(s) in RCA: 81] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Sperm are equipped with a unique set of ion channels that orchestrate fertilization. In mouse sperm, the principal K+ current (IKSper) is carried by the Slo3 channel, which sets the membrane potential (Vm) in a strongly pHi-dependent manner. Here, we show that IKSper in human sperm is activated weakly by pHi and more strongly by Ca2+. Correspondingly, Vm is strongly regulated by Ca2+ and less so by pHi. We find that inhibitors of Slo3 suppress human IKSper, and we identify the Slo3 protein in the flagellum of human sperm. Moreover, heterologously expressed human Slo3, but not mouse Slo3, is activated by Ca2+ rather than by alkaline pHi; current–voltage relations of human Slo3 and human IKSper are similar. We conclude that Slo3 represents the principal K+ channel in human sperm that carries the Ca2+-activated IKSper current. We propose that, in human sperm, the progesterone-evoked Ca2+ influx carried by voltage-gated CatSper channels is limited by Ca2+-controlled hyperpolarization via Slo3. DOI:http://dx.doi.org/10.7554/eLife.01438.001 A sperm that has been ejaculated into the female reproductive tract must complete a number of tasks to pass on its genes to the next generation. First it must travel along a meandering route to encounter an egg, before pushing through a jelly-like coating that surrounds the egg and then, finally, fusing with the egg’s surface membrane. In order to complete these steps and fertilise the egg, a sperm must undergo a process called ‘capacitation’. This process, and a variety of other sperm functions, involves the controlled flux of positive ions into and out of the sperm via specific ion channels that are located in the cell membrane. The properties of the ion channels that allow protons and calcium ions to move into and out of human sperm are well understood, but less is known about the channels that control the movement of potassium ions. In mice, a channel called Slo3 allows potassium ions to flow out of the sperm and makes the membrane voltage of these cells more negative. Also, in mice, this channel is essential for the sperm to function correctly, and for fertilization. However, in humans, it is unclear if the Slo3 channel is present in sperm and if it performs the same role. Now, Brenker et al. have shown that the flow of potassium ions out of human sperm occurs via the Slo3 channel, and that human Slo3 is responsible for setting the membrane voltage of these cells. However, whereas the mouse Slo3 channel is opened in response to a decrease in the concentration of protons within the sperm (i.e., an increase of the pH inside the cell), human Slo3 is largely controlled by changes in the levels of calcium ions. An increase in the calcium concentration within the cell opens the human Slo3 channel, more than a decrease in the proton concentration does. Altogether, Brenker et al. identify Slo3 as the principal potassium channel in human sperm and reveal more fundamental differences between human sperm and mouse sperm. Thereby, this work further stresses the need to be cautious about using mice as a model of male fertility in humans. DOI:http://dx.doi.org/10.7554/eLife.01438.002
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Affiliation(s)
- Christoph Brenker
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research, Bonn, Germany
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Mansell SA, Publicover SJ, Barratt CLR, Wilson SM. Patch clamp studies of human sperm under physiological ionic conditions reveal three functionally and pharmacologically distinct cation channels. Mol Hum Reprod 2014; 20:392-408. [PMID: 24442342 PMCID: PMC4004083 DOI: 10.1093/molehr/gau003] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Whilst fertilizing capacity depends upon a K+ conductance (GK) that allows the spermatozoon membrane potential (Vm) to be held at a negative value, the characteristics of this conductance in human sperm are virtually unknown. We therefore studied the biophysical/pharmacological properties of the K+ conductance in spermatozoa from normal donors held under voltage/current clamp in the whole cell recording configuration. Our standard recording conditions were designed to maintain quasi-physiological, Na+, K+ and Cl− gradients. Experiments that explored the effects of ionic substitution/ion channel blockers upon membrane current/potential showed that resting Vm was dependent upon a hyperpolarizing K+ current that flowed via channels that displayed only weak voltage dependence and limited (∼7-fold) K+ versus Na+ selectivity. This conductance was blocked by quinidine (0.3 mM), bupivacaine (3 mM) and clofilium (50 µM), NNC55-0396 (2 µM) and mibefradil (30 µM), but not by 4-aminopyridine (2 mM, 4-AP). Progesterone had no effect upon the hyperpolarizing K+ current. Repolarization after a test depolarization consistently evoked a transient inward ‘tail current’ (ITail) that flowed via a second population of ion channels with poor (∼3-fold) K+ versus Na+ selectivity. The activity of these channels was increased by quinidine, 4-AP and progesterone. Vm in human sperm is therefore dependent upon a hyperpolarizing K+ current that flows via channels that most closely resemble those encoded by Slo3. Although 0.5 µM progesterone had no effect upon these channels, this hormone did activate the pharmacologically distinct channels that mediate ITail. In conclusion, this study reveals three functionally and pharmacologically distinct cation channels: Ik, ITail, ICatSper.
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Affiliation(s)
- S A Mansell
- Medical Research Institute, College of Medicine, Dentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9S, UK
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González C, Baez-Nieto D, Valencia I, Oyarzún I, Rojas P, Naranjo D, Latorre R. K(+) channels: function-structural overview. Compr Physiol 2013; 2:2087-149. [PMID: 23723034 DOI: 10.1002/cphy.c110047] [Citation(s) in RCA: 143] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Potassium channels are particularly important in determining the shape and duration of the action potential, controlling the membrane potential, modulating hormone secretion, epithelial function and, in the case of those K(+) channels activated by Ca(2+), damping excitatory signals. The multiplicity of roles played by K(+) channels is only possible to their mammoth diversity that includes at present 70 K(+) channels encoding genes in mammals. Today, thanks to the use of cloning, mutagenesis, and the more recent structural studies using x-ray crystallography, we are in a unique position to understand the origins of the enormous diversity of this superfamily of ion channels, the roles they play in different cell types, and the relations that exist between structure and function. With the exception of two-pore K(+) channels that are dimers, voltage-dependent K(+) channels are tetrameric assemblies and share an extremely well conserved pore region, in which the ion-selectivity filter resides. In the present overview, we discuss in the function, localization, and the relations between function and structure of the five different subfamilies of K(+) channels: (a) inward rectifiers, Kir; (b) four transmembrane segments-2 pores, K2P; (c) voltage-gated, Kv; (d) the Slo family; and (e) Ca(2+)-activated SK family, SKCa.
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Affiliation(s)
- Carlos González
- Centro Interdisciplinario de Neurociencia de Valparaíso, Facultad de Ciencias, Universidad de Valparaíso, Valparaíso, Chile
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Mannowetz N, Naidoo NM, Choo SAS, Smith JF, Lishko PV. Slo1 is the principal potassium channel of human spermatozoa. eLife 2013; 2:e01009. [PMID: 24137539 PMCID: PMC3789364 DOI: 10.7554/elife.01009] [Citation(s) in RCA: 78] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 09/02/2013] [Indexed: 12/21/2022] Open
Abstract
Mammalian spermatozoa gain competence to fertilize an oocyte as they travel through the female reproductive tract. This process is accompanied by an elevation of sperm intracellular calcium and a membrane hyperpolarization. The latter is evoked by K(+) efflux; however, the molecular identity of the potassium channel of human spermatozoa (hKSper) is unknown. Here, we characterize hKSper, reporting that it is regulated by intracellular calcium but is insensitive to intracellular alkalinization. We also show that human KSper is inhibited by charybdotoxin, iberiotoxin, and paxilline, while mouse KSper is insensitive to these compounds. Such unique properties suggest that the Slo1 ion channel is the molecular determinant for hKSper. We show that Slo1 is localized to the sperm flagellum and is inhibited by progesterone. Inhibition of hKSper by progesterone may depolarize the spermatozoon to open the calcium channel CatSper, thus raising [Ca(2+)] to produce hyperactivation and allowing sperm to fertilize an oocyte. DOI:http://dx.doi.org/10.7554/eLife.01009.001.
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Affiliation(s)
- Nadja Mannowetz
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Natasha M Naidoo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - Seung-A Sara Choo
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
| | - James F Smith
- Department of Urology, University of California, San Francisco, San Francisco, United States
| | - Polina V Lishko
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States
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Balderas E, Sánchez-Cárdenas C, Chávez J, de la Vega Beltrán J, Gómez-Lagunas F, Treviño C, Darszon A. The anti-inflammatory drug celecoxib inhibits t-type Ca2+
currents in spermatogenic cells yet it elicits the acrosome reaction in mature sperm. FEBS Lett 2013; 587:2412-9. [DOI: 10.1016/j.febslet.2013.05.068] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Revised: 05/28/2013] [Accepted: 05/30/2013] [Indexed: 11/27/2022]
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Zheng LP, Wang HF, Li BM, Zeng XH. Sperm-specific ion channels: targets holding the most potential for male contraceptives in development. Contraception 2013; 88:485-91. [PMID: 23845210 DOI: 10.1016/j.contraception.2013.06.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2013] [Revised: 06/03/2013] [Accepted: 06/04/2013] [Indexed: 12/27/2022]
Abstract
There is a global need for an ideal method of male contraception. However, the development of male contraceptives has not been well successful. Research on sperm-specific ion channels, especially the recent advance obtained from electrophysiological studies, has emphasized the conception that those channels are targets with the most potential to develop non-hormonal male contraceptives. While summarizing the general options for male contraception, this review focuses on the properties and functions of sperm ion channels together with the attempts of utilizing these channels to develop male contraceptives. We believe that a deeper insight into the signaling and molecular mechanisms by which ion channels regulate sperm functions will pave the way for developing novel male-based contraceptives.
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Affiliation(s)
- Li-Ping Zheng
- Institute of Life Science, Nanchang University, Nanchang 330031, China.
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Zhang Z, Tang QY, Alaimo JT, Davies AG, Bettinger JC, Logothetis DE. SLO-2 isoforms with unique Ca(2+) - and voltage-dependence characteristics confer sensitivity to hypoxia in C. elegans. Channels (Austin) 2013; 7:194-205. [PMID: 23590941 DOI: 10.4161/chan.24492] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Slo channels are large conductance K (+) channels that display marked differences in their gating by intracellular ions. Among them, the Slo1 and C. elegans SLO-2 channels are gated by calcium (Ca ( 2+) ), while mammalian Slo2 channels are activated by both sodium (Na (+) ) and chloride (Cl (-) ). Here, we report that SLO-2 channels, SLO-2a and a novel N-terminal variant isoform, SLO-2b, are activated by Ca ( 2+) and voltage, but in contrast to previous reports they do not exhibit Cl (-) sensitivity. Most importantly, SLO-2 provides a unique case in the Slo family for sensing Ca ( 2+) with the high-affinity Ca ( 2+) regulatory site in the RCK1 but not the RCK2 domain, formed through interactions with residues E319 and E487 (that correspond to D362 and E535 of Slo1, respectively). The SLO-2 RCK2 domain lacks the Ca ( 2+) bowl structure and shows minimal Ca ( 2+) dependence. In addition, in contrast to SLO-1, SLO-2 loss-of-function mutants confer resistance to hypoxia in C. elegans. Thus, the C. elegans SLO-2 channels possess unique biophysical and functional properties.
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Affiliation(s)
- Zhe Zhang
- Department of Physiology and Biophysics, Virginia Commonwealth University, Medical College of Virginia Campus, Richmond, VA, USA.
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35
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Chávez JC, de la Vega-Beltrán JL, Escoffier J, Visconti PE, Treviño CL, Darszon A, Salkoff L, Santi CM. Ion permeabilities in mouse sperm reveal an external trigger for SLO3-dependent hyperpolarization. PLoS One 2013; 8:e60578. [PMID: 23577126 PMCID: PMC3618424 DOI: 10.1371/journal.pone.0060578] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2012] [Accepted: 02/28/2013] [Indexed: 12/15/2022] Open
Abstract
Unlike most cells of the body which function in an ionic environment controlled within narrow limits, spermatozoa must function in a less controlled external environment. In order to better understand how sperm control their membrane potential in different ionic conditions, we measured mouse sperm membrane potentials under a variety of conditions and at different external K+ concentrations, both before and after capacitation. Experiments were undertaken using both wild-type, and mutant mouse sperm from the knock-out strain of the sperm-specific, pH-sensitive, SLO3 K+ channel. Membrane voltage data were fit to the Goldman-Hodgkin-Katz equation. Our study revealed a significant membrane permeability to both K+ and Cl− before capacitation, as well as Na+. The permeability to both K+ and Cl− has the effect of preventing large changes in membrane potential when the extracellular concentration of either ion is changed. Such a mechanism may protect against undesired shifts in membrane potential in changing ionic environments. We found that a significant portion of resting membrane potassium permeability in wild-type sperm was contributed by SLO3 K+ channels. We also found that further activation of SLO3 channels was the essential mechanism producing membrane hyperpolarization under two separate conditions, 1) elevation of external pH prior to capacitation and 2) capacitating conditions. Both conditions produced a significant membrane hyperpolarization in wild-type which was absent in SLO3 mutant sperm. Hyperpolarization in both conditions may result from activation of SLO3 channels by raising intracellular pH; however, demonstrating that SLO3-dependent hyperpolarization is achieved by an alkaline environment alone shows that SLO3 channel activation might occur independently of other events associated with capacitation. For example sperm may undergo stages of membrane hyperpolarization when reaching alkaline regions of the female genital tract. Significantly, other events associated with sperm capacitation, occur in SLO3 mutant sperm and thus proceed independently of hyperpolarization.
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Affiliation(s)
- Julio C. Chávez
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - José L. de la Vega-Beltrán
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Jessica Escoffier
- Department of Veterinary and Animal Science, Integrated Sciences Building, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Pablo E. Visconti
- Department of Veterinary and Animal Science, Integrated Sciences Building, University of Massachusetts, Amherst, Massachusetts, United States of America
| | - Claudia L. Treviño
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Alberto Darszon
- Departamento de Genética del Desarrollo y Fisiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México
| | - Lawrence Salkoff
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Celia M. Santi
- Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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Smith FJ, Rothberg BS. Analysis of Ca(2+)-binding sites in the MthK RCK domain by X-ray crystallography. Methods Mol Biol 2013; 998:277-287. [PMID: 23529438 DOI: 10.1007/978-1-62703-351-0_22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Regulator of K(+) conductance (RCK) domains form a conserved class of ligand-binding domains that control the activity of a variety of prokaryotic and eukaryotic K(+) channels. Structural analysis of these domains by X-ray crystallography has provided insight toward mechanisms underlying ligand binding and channel gating, and thus the experimental strategies aimed at determining structures of liganded and unliganded forms of the domains may be useful in analysis of other ligand-binding domains. Here, we describe a basic strategy for crystallographic analysis of the RCK domain from the MthK channel, for determination of its Ca(2+)-bound structure.
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Affiliation(s)
- Frank J Smith
- Department of Biochemistry, Temple University School of Medicine, Philadelphia, PA, USA
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Functional and structural analysis of the human SLO3 pH- and voltage-gated K+ channel. Proc Natl Acad Sci U S A 2012; 109:19274-9. [PMID: 23129643 DOI: 10.1073/pnas.1215078109] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The activation of eukaryotic SLO K(+) channels by intracellular cues, mediated by a cytoplasmic structure called the gating ring, is central to their physiological roles. SLO3 channels are exclusively expressed in mammalian sperm, where variations of intracellular pH are critical to cellular function. Previous studies primarily focused on the mouse SLO3 orthologue and revealed that, in murine sperm, SLO3 mediates a voltage- and alkalization-activated K(+) current essential to male fertility. Here we investigate the activation of the human SLO3 channel by intracellular pH at the functional and structural level. By using electrophysiology in a heterologous system, we show that human SLO3 opens upon intracellular pH increase and that its expression and functional properties are modulated by LRRC52, a testis-specific accessory subunit. We next present the crystal structure of the human SLO3 gating ring. Comparison with the known structures of the corresponding domain from SLO1, a Ca(2+)-activated homologue, suggests that the SLO3 gating ring structure may represent an open state. Together, these results present insights into the function of a protein expected to be critical for human reproduction and provide a framework to study the mechanism of pH gating in SLO3 channels.
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LRRC52 (leucine-rich-repeat-containing protein 52), a testis-specific auxiliary subunit of the alkalization-activated Slo3 channel. Proc Natl Acad Sci U S A 2011; 108:19419-24. [PMID: 22084117 DOI: 10.1073/pnas.1111104108] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
KSper, a pH-dependent K(+) current in mouse spermatozoa that is critical for fertility, is activated by alkalization in the range of pH 6.4-7.2 at membrane potentials between -50 and 0 mV. Although the KSper pore-forming subunit is encoded by the Slo3 gene, heterologously expressed Slo3 channels are largely closed at potentials negative to 0 mV at physiological pH. Here we identify a Slo3-associating protein, LRRC52 (leucine-rich repeat-containing 52), that shifts Slo3 gating into a range of voltages and pH values similar to that producing KSper current activation. Message for LRRC52, a homolog of the Slo1-modifying LRRC26 protein, is enriched in testis relative to other homologous LRRC subunits and is developmentally regulated in concert with that for Slo3. LRRC52 protein is detected only in testis. It is markedly diminished from Slo3(-/-) testis and completely absent from Slo3(-/-) sperm, indicating that LRRC52 expression is critically dependent on the presence of Slo3. We also examined the ability of other LRRC subunits homologous to LRRC26 and LRRC52 to modify Slo3 currents. Although both LRRC26 and LRRC52 are able to modify Slo3 function, LRRC52 is the stronger modifier of Slo3 function. Effects of other related subunits were weaker or absent. We propose that LRRC52 is a testis-enriched Slo3 auxiliary subunit that helps define the specific alkalization dependence of KSper activation. Together, LRRC52 and LRRC26 define a new family of auxiliary subunits capable of critically modifying the gating behavior of Slo family channels.
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Lishko PV, Kirichok Y, Ren D, Navarro B, Chung JJ, Clapham DE. The control of male fertility by spermatozoan ion channels. Annu Rev Physiol 2011; 74:453-75. [PMID: 22017176 DOI: 10.1146/annurev-physiol-020911-153258] [Citation(s) in RCA: 246] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Ion channels control the sperm ability to fertilize the egg by regulating sperm maturation in the female reproductive tract and by triggering key sperm physiological responses required for successful fertilization such as hyperactivated motility, chemotaxis, and the acrosome reaction. CatSper, a pH-regulated, calcium-selective ion channel, and KSper (Slo3) are core regulators of sperm tail calcium entry and sperm hyperactivated motility. Many other channels had been proposed as regulating sperm activity without direct measurements. With the development of the sperm patch-clamp technique, CatSper and KSper have been confirmed as the primary spermatozoan ion channels. In addition, the voltage-gated proton channel Hv1 has been identified in human sperm tail, and the P2X2 ion channel has been identified in the midpiece of mouse sperm. Mutations and deletions in sperm-specific ion channels affect male fertility in both mice and humans without affecting other physiological functions. The uniqueness of sperm ion channels makes them ideal pharmaceutical targets for contraception. In this review we discuss how ion channels regulate sperm physiology.
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Affiliation(s)
- Polina V Lishko
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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40
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Deletion of the Slo3 gene abolishes alkalization-activated K+ current in mouse spermatozoa. Proc Natl Acad Sci U S A 2011; 108:5879-84. [PMID: 21427226 DOI: 10.1073/pnas.1100240108] [Citation(s) in RCA: 140] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mouse spermatozoa express a pH-dependent K(+) current (KSper) thought to be composed of subunits encoded by the Slo3 gene. However, the equivalence of KSper and Slo3-dependent current remains uncertain, because heterologous expression of Slo3 results in currents that are less effectively activated by alkalization than are native KSper currents. Here, we show that genetic deletion of Slo3 abolishes all pH-dependent K(+) current at physiological membrane potentials in corpus epididymal sperm. A residual pH-dependent outward current (I(Kres)) is observed in Slo3(-/-) sperm at potentials of >0 mV. Differential inhibition of KSper/Slo3 and I(Kres) by clofilium reveals that the amplitude of I(Kres) is similar in both wild-type (wt) and Slo3(-/-) sperm. The properties of I(Kres) suggest that it likely represents outward monovalent cation flux through CatSper channels. Thus, KSper/Slo3 may account for essentially all mouse sperm K(+) current and is the sole pH-dependent K(+) conductance in these sperm. With physiological ionic gradients, alkalization depolarizes Slo3(-/-) spermatozoa, presumably from CatSper activation, in contrast to Slo3/KSper-mediated hyperpolarization in wt sperm. Slo3(-/-) male mice are infertile, but Slo3(-/-) sperm exhibit some fertility within in vitro fertilization assays. Slo3(-/-) sperm exhibit a higher incidence of morphological abnormalities accentuated by hypotonic challenge and also exhibit deficits in motility in the absence of bicarbonate, revealing a role of KSper under unstimulated conditions. Together, these results show that KSper/Slo3 is the primary spermatozoan K(+) current, that KSper may play a critical role in acquisition of normal morphology and sperm motility when faced with hyperosmotic challenges, and that Slo3 is critical for fertility.
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Zhou Y, Tang QY, Xia XM, Lingle CJ. Glycine311, a determinant of paxilline block in BK channels: a novel bend in the BK S6 helix. ACTA ACUST UNITED AC 2010; 135:481-94. [PMID: 20421373 PMCID: PMC2860595 DOI: 10.1085/jgp.201010403] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The tremorogenic fungal metabolite, paxilline, is widely used as a potent and relatively specific blocker of Ca2+- and voltage-activated Slo1 (or BK) K+ channels. The pH-regulated Slo3 K+ channel, a Slo1 homologue, is resistant to blockade by paxilline. Taking advantage of the marked differences in paxilline sensitivity and the homology between subunits, we have examined the paxilline sensitivity of a set of chimeric Slo1/Slo3 subunits. Paxilline sensitivity is associated with elements of the S5–P loop–S6 module of the Slo1 channel. Replacement of the Slo1 S5 segment or the second half of the P loop results in modest changes in paxilline sensitivity. Replacing the Slo1 S6 segment with the Slo3 sequence abolishes paxilline sensitivity. An increase in paxilline affinity and changes in block kinetics also result from replacing the first part of the Slo1 P loop, the so-called turret, with Slo3 sequence. The Slo1 and Slo3 S6 segments differ at 10 residues. Slo1-G311S was found to markedly reduce paxilline block. In constructs with a Slo3 S6 segment, S300G restored paxilline block, but most effectively when paired with a Slo1 P loop. Other S6 residues differing between Slo1 and Slo3 had little influence on paxilline block. The involvement of Slo1 G311 in paxilline sensitivity suggests that paxilline may occupy a position within the central cavity or access its blocking position through the central cavity. To explain the differences in paxilline sensitivity between Slo1 and Slo3, we propose that the G311/S300 position in Slo1 and Slo3 underlies a structural difference between subunits in the bend of S6, which influences the occupancy by paxilline.
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Affiliation(s)
- Yu Zhou
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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42
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Tang QY, Zhang Z, Xia J, Ren D, Logothetis DE. Phosphatidylinositol 4,5-bisphosphate activates Slo3 currents and its hydrolysis underlies the epidermal growth factor-induced current inhibition. J Biol Chem 2010; 285:19259-66. [PMID: 20392696 PMCID: PMC2885204 DOI: 10.1074/jbc.m109.100156] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2010] [Revised: 03/20/2010] [Indexed: 11/06/2022] Open
Abstract
The Slo3 gene encodes a high conductance potassium channel, which is activated by both voltage and intracellular alkalinization. Slo3 is specifically expressed in mammalian sperm cells, where it gives rise to pH-dependent outwardly rectifying K(+) currents. Sperm Slo3 is the main current responsible for the capacitation-induced hyperpolarization, which is required for the ensuing acrosome reaction, an exocytotic process essential for fertilization. Here we show that in intact spermatozoa and in a heterologous expression system, the activation of Slo3 currents is regulated by phosphatidylinositol 4,5-bisphosphate (PIP(2)). Depletion of endogenous PIP(2) in inside-out macropatches from Xenopus oocytes inhibited heterologously expressed Slo3 currents. Whole-cell recordings of sperm Slo3 currents or of Slo3 channels co-expressed in Xenopus oocytes with epidermal growth factor receptor, demonstrated that stimulation by epidermal growth factor (EGF) could inhibit channel activity in a PIP(2)-dependent manner. High concentrations of PIP(2) in the patch pipette not only resulted in a strong increase in sperm Slo3 current density but also prevented the EGF-induced inhibition of this current. Mutation of positively charged residues involved in channel-PIP(2) interactions enhanced the EGF-induced inhibition of Slo3 currents. Overall, our results suggest that PIP(2) is an important regulator for Slo3 activation and that receptor-mediated hydrolysis of PIP(2) leads to inhibition of Slo3 currents both in native and heterologous expression systems.
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Affiliation(s)
- Qiong-Yao Tang
- From the Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298-0551 and
| | - Zhe Zhang
- From the Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298-0551 and
| | - Jingsheng Xia
- the Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Dejian Ren
- the Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Diomedes E. Logothetis
- From the Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298-0551 and
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43
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Tang QY, Zeng XH, Lingle CJ. Closed-channel block of BK potassium channels by bbTBA requires partial activation. ACTA ACUST UNITED AC 2010; 134:409-36. [PMID: 19858359 PMCID: PMC2768800 DOI: 10.1085/jgp.200910251] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Blockade of large-conductance Ca2+-activated K+ (BK) channels by the bulky quaternary ammonium compound, N-(4-[benzoyl]benzyl)-N,N,N-tributylammonium (bbTBA), exhibits features consistent with blockade of both closed and open states. Here, we examine block of closed BK channels by bbTBA and how it may differ from block of open channels. Although our observations generally confirm earlier results, we describe three observations that are inconsistent with a model in which closed and open channels are equally accessible to blockade by bbTBA. First, block by bbTBA exhibits Ca2+-dependent features that are inconsistent with strictly state-independent block. Second, the steady-state voltage dependence of bbTBA block at negative potentials shows that any block of completely closed states either does not occur or is completely voltage independent. Third, determination of the fractional unblock by bbTBA at either low or high Ca2+ reveals deviations from a model in which open- and closed-state block is identical. The results support the view that bbTBA blockade of fully closed channels does not occur. We imagine two general types of explanation. First, a stronger voltage dependence of closed-channel block may minimize the contribution of closed-channel block at negative potentials. Second, voltage-dependent conformational changes among closed-channel states may permit block by bbTBA. The analysis supports the latter view, suggesting that bbTBA blockade of fully closed channels does not occur, but the ability of bbTBA to block a closed channel requires movement of one or more voltage sensors. Models in which block is coupled to voltage sensor movement can qualitatively account for (1) the ability of open-channel block to better fit block of conductance–voltage curves at high Ca2+; (2) the voltage dependence of fractional availability; and (3) the fractional unblock at different open probabilities. BK channels appear to undergo voltage-dependent conformational changes among closed states that are permissive for bbTBA block.
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Affiliation(s)
- Qiong-Yao Tang
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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44
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Tang QY, Zhang Z, Xia XM, Lingle CJ. Block of mouse Slo1 and Slo3 K+ channels by CTX, IbTX, TEA, 4-AP and quinidine. Channels (Austin) 2010; 4:22-41. [PMID: 19934650 PMCID: PMC3723589 DOI: 10.4161/chan.4.1.10481] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
pH-regulated Slo3 channels, perhaps exclusively expressed in mammalian sperm, may play a role in alkalization-mediated K+ fluxes associated with sperm capacitation. The Slo3 channel shares extensive homology with Ca2+- and voltage-regulated BK-type Slo1 K+ channels. Here, using heterologous expression in oocytes, we define distinctive differences in pharmacological properties of Slo3 and Slo1 currents, examine blockade in terms of distinct blocking models, and, for some blockers, use mutated constructs to evaluate determinants of block. Slo3 is resistant to block by the standard Slo1 blockers, iberiotoxin, charybdotoxin and extracellular TEA. Slo3 is relatively insensitive to extracellular 4-AP up to 100 mM, while Slo1 is blocked in a voltage-dependent fashion consistent with block on the extracellular side of the channel. Block of both Slo1 and Slo3 by cytosolic 4-AP can be described by open channel block, with Slo3 being ~10–15-fold more sensitive, but exhibiting weaker voltage-dependence of block. The cytosolic concentrations of 4-AP required to block Slo3 make it unlikely that the effects of 4-AP on volume regulation in mammalian sperm is mediated by Slo3. Quinidine was more effective in blocking Slo3 than Slo1. For Slo1, quinidine block was favored by depolarization, irrespective of the side of application. For Slo3, quinidine block was relieved by depolarization, irrespective of the side of application, with strong block by less than 10 μM quinidine at potentials near 0 mV. The unusual voltage-dependence of block of Slo3 by quinidine may result from preferential binding of quinidine to closed Slo3 channels. The quinidine concentrations effective in blocking Slo3 suggest, that in experiments that have examined quinidine effects on sperm, any Slo3 currents would be almost completely inhibited.
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Affiliation(s)
- Qiong-Yao Tang
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, MO, USA
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45
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Yang CT, Zeng XH, Xia XM, Lingle CJ. Interactions between beta subunits of the KCNMB family and Slo3: beta4 selectively modulates Slo3 expression and function. PLoS One 2009; 4:e6135. [PMID: 19578543 PMCID: PMC2701609 DOI: 10.1371/journal.pone.0006135] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2009] [Accepted: 06/01/2009] [Indexed: 01/30/2023] Open
Abstract
BACKGROUND The pH and voltage-regulated Slo3 K(+) channel, a homologue of the Ca(2+)- and voltage-regulated Slo1 K(+) channel, is thought to be primarily expressed in sperm, but the properties of Slo3 studied in heterologous systems differ somewhat from the native sperm KSper pH-regulated current. There is the possibility that critical partners that regulate Slo3 function remain unidentified. The extensive amino acid identity between Slo3 and Slo1 suggests that auxiliary beta subunits regulating Slo1 channels might coassemble with and modulate Slo3 channels. Four distinct beta subunits composing the KCNMB family are known to regulate the function and expression of Slo1 Channels. METHODOLOGY/PRINCIPAL FINDINGS To examine the ability of the KCNMB family of auxiliary beta subunits to regulate Slo3 function, we co-expressed Slo3 and each beta subunit in heterologous expression systems and investigated the functional consequences by electrophysiological and biochemical analyses. The beta4 subunit produced an 8-10 fold enhancement of Slo3 current expression in Xenopus oocytes and a similar enhancement of Slo3 surface expression as monitored by YFP-tagged Slo3 or biotin labeled Slo3. Neither beta1, beta2, nor beta3 mimicked the ability of beta4 to increase surface expression, although biochemical tests suggested that all four beta subunits are competent to coassemble with Slo3. Fluorescence microscopy from beta4 KO mice, in which an eGFP tag replaced the deleted exon, revealed that beta4 gene promoter is active in spermatocytes. Furthermore, quantitative RT-PCR demonstrated that beta4 and Slo3 exhibit comparable mRNA abundance in both testes and sperm. CONCLUSIONS/SIGNIFICANCE These results argue that, for native mouse Slo3 channels, the beta4 subunit must be considered as a potential interaction partner and, furthermore, that KCNMB subunits may have functions unrelated to regulation of the Slo1 alpha subunit.
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Affiliation(s)
- Cheng-Tao Yang
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Xu-Hui Zeng
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail: (XHZ); (CJL)
| | - Xiao-Ming Xia
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Christopher J. Lingle
- Department of Anesthesiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail: (XHZ); (CJL)
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Giangiacomo KM, Becker J, Garsky C, Schmalhofer W, Garcia ML, Mullmann TJ. Novel α-KTx Sites in the BK Channel and Comparative Sequence Analysis Reveal Distinguishing Features of the BK and KV Channel Outer Pore. Cell Biochem Biophys 2008; 52:47-58. [DOI: 10.1007/s12013-008-9026-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2008] [Indexed: 01/30/2023]
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47
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Affiliation(s)
- Christopher J Lingle
- Department of Anesthesiology, Washington University School of Medicine, MO 63105, USA.
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48
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Abstract
Here we have examined the voltage and pH dependence of unitary Slo3 channels and used analysis of current variance to define Slo3 unitary current properties over a broader range of voltages. Despite complexity in Slo3 channel openings that precludes simple definition of the unitary conductance, average current through single Slo3 channels varies linearly with voltage at positive activation potentials. Furthermore, the average Slo3 unitary current at a given activation potential does not change with pH. Consistent with macroscopic conductance estimates, the apparent open probability of Slo3 channel exhibits a pH-dependent maximum, with limiting values around 0.3 at the most elevated pH and voltage. Estimates of Slo3 conductance at negative potentials support a weaker intrinsic voltage dependence of gating than is observed for Slo1. For the pH-regulated Slo3 K+ channel, the dependence of macroscopic conductance on pH suggests that the pH-sensitive mechanism regulates gating in an allosteric manner qualitatively similar to regulation of Slo1 by Ca2+. Together, the results support the view that the regulation of macroscopic Slo3 currents by pH reflects regulation of gating equilibria, and not a direct effect of pH on ion permeation. Specifically, both voltage and pH regulate a closed–open conformational change in a largely independent fashion.
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Affiliation(s)
- Xue Zhang
- Department of Anesthesiology and Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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