Human sperm ion channel (dys)function: implications for fertilization

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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Phosphorylation-Dependent Regulation of Ryanodine Receptors

The Journal of Cell Biology ◽

10.1083/jcb.153.4.699 ◽

2001 ◽

Vol 153 (4) ◽

pp. 699-708 ◽

Cited By ~ 196

Author(s):

Steven O. Marx ◽

Steven Reiken ◽

Yuji Hisamatsu ◽

Marta Gaburjakova ◽

Jana Gaburjakova ◽

...

Keyword(s):

Ion Channels ◽

Ion Channel ◽

Calcium Release ◽

Ryanodine Receptors ◽

Rapid Identification ◽

Calcium Release Channels ◽

Macromolecular Complexes ◽

Protein Binding Sites ◽

Skeletal Muscle Contraction

Ryanodine receptors (RyRs), intracellular calcium release channels required for cardiac and skeletal muscle contraction, are macromolecular complexes that include kinases and phosphatases. Phosphorylation/dephosphorylation plays a key role in regulating the function of many ion channels, including RyRs. However, the mechanism by which kinases and phosphatases are targeted to ion channels is not well understood. We have identified a novel mechanism involved in the formation of ion channel macromolecular complexes: kinase and phosphatase targeting proteins binding to ion channels via leucine/isoleucine zipper (LZ) motifs. Activation of kinases and phosphatases bound to RyR2 via LZs regulates phosphorylation of the channel, and disruption of kinase binding via LZ motifs prevents phosphorylation of RyR2. Elucidation of this new role for LZs in ion channel macromolecular complexes now permits: (a) rapid mapping of kinase and phosphatase targeting protein binding sites on ion channels; (b) predicting which kinases and phosphatases are likely to regulate a given ion channel; (c) rapid identification of novel kinase and phosphatase targeting proteins; and (d) tools for dissecting the role of kinases and phosphatases as modulators of ion channel function.

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Non-genomic effects of steroid hormones: role of ion channels

Journal of the Belarusian State University Biology ◽

10.33581/2521-1722-2019-3-3-12 ◽

2019 ◽

pp. 3-12 ◽

Cited By ~ 2

Author(s):

Darya Y. Straltsova ◽

Maryia A. Charnysh ◽

Palina V. Hryvusevich ◽

Vadim V. Demidchik

Keyword(s):

Ion Channels ◽

Ion Channel ◽

Steroid Hormones ◽

Plant Cells ◽

Membrane Receptors ◽

Physiological Effects ◽

Genomic Effects

In animals, steroid hormones can act using genomic and non-genomic mechanisms. Plant steroid hormones, brassinosteroids, are capable of inducing the expression of some gene ensembles, however their non-genomic pathways for triggering the physiological effects are still unclear. In this paper, we propose the hypothesis on existence of brassinosteroid non-genomic effects in plant cells. This non-genomic pathway could due to modulation of ion channel activities and modification of membrane receptors.

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Actin dynamics as critical ion channel regulator: ENaC and Piezo in focus

AJP Cell Physiology ◽

10.1152/ajpcell.00368.2020 ◽

2021 ◽

Author(s):

Elena A. Morachevskaya ◽

Anastasia V. Sudarikova

Keyword(s):

Ion Channels ◽

Ion Channel ◽

Dynamic Balance ◽

Cell Volume Regulation ◽

Actin Dynamics ◽

Actin Binding ◽

Actin Assembly ◽

Excitable Cells ◽

Physiological Processes

Ion channels in plasma membrane play a principal role in different physiological processes, including cell volume regulation, signal transduction and modulation of membrane potential in living cells. Actin-based cytoskeleton, which exists in a dynamic balance between monomeric and polymeric forms (globular and fibrillar actin), can be directly or indirectly involved in various cellular responses including modulation of ion channel activity. In this mini-review, we present an overview of the role of submembranous actin dynamics in the regulation of ion channels in excitable and non-excitable cells. Special attention is focused on the important data about the involvement of actin assembly/disassembly and some actin-binding proteins in the control of the Epithelial Na+ Channel (ENaC) and mechanosensitive Piezo channels whose integral activity has potential impact on membrane transport and multiple coupled cellular reactions. Growing evidence suggests that actin elements of the cytoskeleton can represent a "converging point" of various signaling pathways modulating the activity of ion transport proteins in cell membranes.

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Regulation of Survivin Isoform Expression by GLI Proteins in Ovarian Cancer

Cells ◽

10.3390/cells8020128 ◽

2019 ◽

Vol 8 (2) ◽

pp. 128 ◽

Cited By ~ 2

Author(s):

Diana Trnski ◽

Maja Gregorić ◽

Sonja Levanat ◽

Petar Ozretić ◽

Nikolina Rinčić ◽

...

Keyword(s):

Ovarian Cancer ◽

Cell Line ◽

Treatment Options ◽

Clinical Samples ◽

Knock Out ◽

Gynecological Malignancy ◽

Gli Proteins ◽

Apoptosis Protein ◽

Isoform Expression

Ovarian cancer (OC) is the most lethal female gynecological malignancy, mostly due to diagnosis in late stages when treatment options are limited. Hedgehog-GLI (HH-GLI) signaling is a major developmental pathway involved in organogenesis and stem cell maintenance, and is activated in OC. One of its targets is survivin (BIRC5), an inhibitor of apoptosis protein (IAP) that plays a role in multiple processes, including proliferation and cell survival. We wanted to investigate the role of different GLI proteins in the regulation of survivin isoform expression (WT, 2α, 2B, 3B, and Δex3) in the SKOV-3 OC cell line. We demonstrated that survivin isoforms are downregulated in GLI1 and GLI2 knock-out cell lines, but not in the GLI3 knock-out. Treatment of GLI1 knock-out cells with GANT-61 shows an additional inhibitory effect on several isoforms. Additionally, we examined the expression of survivin isoforms in OC samples and the potential role of BIRC5 polymorphisms in isoform expression. Clinical samples showed the same pattern of survivin isoform expression as in the cell line, and several BIRC5 polymorphisms showed the correlation with isoform expression. Our results showed that survivin isoforms are regulated both by different GLI proteins and BIRC5 polymorphisms in OC.

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Computational biology in the study of cardiac ion channels and cell electrophysiology

Quarterly Reviews of Biophysics ◽

10.1017/s0033583506004227 ◽

2006 ◽

Vol 39 (1) ◽

pp. 57-116 ◽

Cited By ~ 178

Author(s):

Yoram Rudy ◽

Jonathan R. Silva

Keyword(s):

Ion Channels ◽

Action Potential ◽

Ion Channel ◽

Markov Models ◽

Cardiac Action Potential ◽

Genetic Mutations ◽

Cardiac Ion Channels ◽

Cardiac Action ◽

Ion Channel Kinetics

1. Prologue 582. The Hodgkin–Huxley formalism for computing the action potential 592.1 The axon action potential model 592.2 Cardiac action potential models 623. Ion-channel based formulation of the action potential 653.1 Ion-channel structure 653.2 Markov models of ion-channel kinetics 663.3 Role of selected ion channels in rate dependence of the cardiac action potential 713.4 Physiological implications of IKs subunit interaction 773.5 Mechanism of cardiac action potential rate-adaptation is species dependent 784. Simulating ion-channel mutations and their electrophysiological consequences 814.1 Mutations in SCN5A, the gene that encodes the cardiac sodium channel 824.1.1 The ΔKPQ mutation and LQT3 824.1.2 SCN5A mutation that underlies a dual phenotype 874.2 Mutations in HERG, the gene that encodes IKr: re-examination of the ‘gain of function/loss of function’ concept 944.3 Role of IKs as ‘repolarization reserve’ 1005. Modeling cell signaling in electrophysiology 1025.1 CaMKII regulation of the Ca2+ transient 1025.2 The β-adrenergic signaling cascade 1056. Epilogue 1077. Acknowledgments 1088. References 109The cardiac cell is a complex biological system where various processes interact to generate electrical excitation (the action potential, AP) and contraction. During AP generation, membrane ion channels interact nonlinearly with dynamically changing ionic concentrations and varying transmembrane voltage, and are subject to regulatory processes. In recent years, a large body of knowledge has accumulated on the molecular structure of cardiac ion channels, their function, and their modification by genetic mutations that are associated with cardiac arrhythmias and sudden death. However, ion channels are typically studied in isolation (in expression systems or isolated membrane patches), away from the physiological environment of the cell where they interact to generate the AP. A major challenge remains the integration of ion-channel properties into the functioning, complex and highly interactive cell system, with the objective to relate molecular-level processes and their modification by disease to whole-cell function and clinical phenotype. In this article we describe how computational biology can be used to achieve such integration. We explain how mathematical (Markov) models of ion-channel kinetics are incorporated into integrated models of cardiac cells to compute the AP. We provide examples of mathematical (computer) simulations of physiological and pathological phenomena, including AP adaptation to changes in heart rate, genetic mutations in SCN5A and HERG genes that are associated with fatal cardiac arrhythmias, and effects of the CaMKII regulatory pathway and β-adrenergic cascade on the cell electrophysiological function.

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Beta-defensin126 is correlated with sperm motility in fertile and infertile men†

Biology of Reproduction ◽

10.1093/biolre/ioz171 ◽

2019 ◽

Cited By ~ 1

Author(s):

Raheleh Aram ◽

Peter T K Chan ◽

Daniel G Cyr

Keyword(s):

Sperm Motility ◽

Human Sperm ◽

Sperm Maturation ◽

Normal Morphology ◽

Testicular Spermatozoa ◽

Men 2 ◽

Infertile Men ◽

Myoblast Cells

Abstract A crucial function of the epididymis is providing a surface glycocalyx that is important for sperm maturation and capacitation. Defensins are antimicrobial peptides expressed in the epididymis. In the macaque epididymis, defensin beta 126 (DEFB126) is important for sperm motility, however, it is not known whether this is the case in humans. The objectives were to determine: (1) if DEFB126 on human ejaculated sperm was correlated with sperm motility in fertile and infertile men, (2) that recombinant DEFB126 could induce immature sperm motility in vitro. Immunofluorescence staining indicated that the proportion of DEFB126-positive sperm was significantly higher in motile sperm. Furthermore, the proportion of DEFB126-labeled sperm was positively correlated with sperm motility and normal morphology. Additional studies indicated that the proportion of DEFB126-positive spermatozoa in fertile volunteers was significantly higher than in volunteers with varicocele, and in infertile volunteers with semen deficiencies. To determine the role of DEFB126 on sperm motility, the DEFB126 gene was cloned and used to generate recombinant DEFB126 in H9C2 cells (rat embryonic heart myoblast cells). Deletion mutations were created into two regions of the protein, which have been linked to male infertility. Immotile testicular spermatozoa were incubated with cells expressing the different forms of DEFB126. Full-length DEFB126 significantly increased motility of co-cultured spermatozoa. However, no increase in sperm motility was observed with the mutated forms of DEFB126. In conclusion, these results support the notion that DEFB126 is important in human sperm maturation and the potential use of DEFB126 for in vitro sperm maturation.

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Ion Channel Dysfunction and Neuroinflammation in Migraine and Depression

Frontiers in Pharmacology ◽

10.3389/fphar.2021.777607 ◽

2021 ◽

Vol 12 ◽

Author(s):

Emine Eren-Koçak ◽

Turgay Dalkara

Keyword(s):

Ion Channels ◽

Ion Channel ◽

Energy Homeostasis ◽

Inflammatory Signaling ◽

Pannexin 1 ◽

Significant Heritability ◽

Homeostatic Function ◽

And Function ◽

Excitability Of Neurons

Migraine and major depression are debilitating disorders with high lifetime prevalence rates. Interestingly these disorders are highly comorbid and show significant heritability, suggesting shared pathophysiological mechanisms. Non-homeostatic function of ion channels and neuroinflammation may be common mechanisms underlying both disorders: The excitation-inhibition balance of microcircuits and their modulation by monoaminergic systems, which depend on the expression and function of membrane located K+, Na+, and Ca+2 channels, have been reported to be disturbed in both depression and migraine. Ion channels and energy supply to synapses not only change excitability of neurons but can also mediate the induction and maintenance of inflammatory signaling implicated in the pathophysiology of both disorders. In this respect, Pannexin-1 and P2X7 large-pore ion channel receptors can induce inflammasome formation that triggers release of pro-inflammatory mediators from the cell. Here, the role of ion channels involved in the regulation of excitation-inhibition balance, synaptic energy homeostasis as well as inflammatory signaling in migraine and depression will be reviewed.

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Mining recent brain proteomic databases for ion channel phosphosite nuggets

The Journal of General Physiology ◽

10.1085/jgp.201010555 ◽

2010 ◽

Vol 137 (1) ◽

pp. 3-16 ◽

Cited By ~ 19

Author(s):

Oscar Cerda ◽

Je-Hyun Baek ◽

James S. Trimmer

Keyword(s):

Ion Channels ◽

Ion Channel ◽

Mammalian Brain ◽

Phosphorylation Sites ◽

Dynamic Regulation ◽

Voltage Gated ◽

Voltage Gated Ion Channels ◽

Α Subunits

Voltage-gated ion channels underlie electrical activity of neurons and are dynamically regulated by diverse cell signaling pathways that alter their phosphorylation state. Recent global mass spectrometric–based analyses of the mouse brain phosphoproteome have yielded a treasure trove of new data as to the extent and nature of phosphorylation of numerous ion channel principal or α subunits in mammalian brain. Here we compile and review data on 347 phosphorylation sites (261 unique) on 42 different voltage-gated ion channel α subunits that were identified in these recent studies. Researchers in the ion channel field can now begin to explore the role of these novel in vivo phosphorylation sites in the dynamic regulation of the localization, activity, and expression of brain ion channels through multisite phosphorylation of their principal subunits.

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Speed, adaptation, and stability of the response to light in cone photoreceptors: The functional role of Ca-dependent modulation of ligand sensitivity in cGMP-gated ion channels

The Journal of General Physiology ◽

10.1085/jgp.201110654 ◽

2011 ◽

Vol 139 (1) ◽

pp. 31-56 ◽

Cited By ~ 16

Author(s):

Juan I. Korenbrot

Keyword(s):

Ion Channels ◽

Ion Channel ◽

Critical Role ◽

Enzymatic Reactions ◽

Cone Photoreceptors ◽

Channel Modulation ◽

Ion Channel Modulation ◽

Gated Ion Channels ◽

Ligand Sensitivity

The response of cone photoreceptors to light is stable and reproducible because of the exceptional regulation of the cascade of enzymatic reactions that link visual pigment (VP) excitation to the gating of cyclic GMP (cGMP)-gated ion channels (cyclic nucleotide–gated [CNG]) in the outer segment plasma membrane. Regulation is achieved in part through negative feedback control of some of these reactions by cytoplasmic free Ca2+. As part of the control process, Ca2+ regulates the phosphorylation of excited VP, the activity of guanylate cyclase, and the ligand sensitivity of the CNG ion channels. We measured photocurrents elicited by stimuli in the form of flashes, steps, and flashes superimposed on steps in voltage-clamped single bass cones isolated from striped bass retina. We also developed a computational model that comprises all the known molecular events of cone phototransduction, including all Ca-dependent controls. Constrained by available experimental data in bass cones and cone transduction biochemistry, we achieved an excellent match between experimental photocurrents and those simulated by the model. We used the model to explore the physiological role of CNG ion channel modulation. Control of CNG channel activity by both cGMP and Ca2+ causes the time course of the light-dependent currents to be faster than if only cGMP controlled their activity. Channel modulation also plays a critical role in the regulation of the light sensitivity and light adaptation of the cone photoresponse. In the absence of ion channel modulation, cone photocurrents would be unstable, oscillating during and at the offset of light stimuli.

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Role of the Ether-a-gò-gò-Related Gene 1B Isoform in Hematopoiesis

Blood ◽

10.1182/blood.v120.21.1222.1222 ◽

2012 ◽

Vol 120 (21) ◽

pp. 1222-1222

Author(s):

Serena Pillozzi ◽

Marika Masselli ◽

Marinella Veltroni ◽

Emanuele De Lorenzo ◽

Antonella Fiore ◽

...

Keyword(s):

Ion Channels ◽

Conflicts Of Interest ◽

Hematopoietic Cells ◽

Membrane Receptors ◽

Stress Tests ◽

Related Gene ◽

Hematopoietic Stem ◽

Knock Out ◽

Functional Defect

Abstract Abstract 1222 Normal hematopoiesis is characterized by the tuned regulation of self renewal, proliferation, differentiation and migration of hematopoietic stem cells and HSC-derived multipotent and lineage-committed hemopoietic progenitor cells. This regulation is a complex process, which requires several levels of control provided by the activity of numerous membrane receptors and soluble proteins, which mediate the communication among hematopoietic cells, and between the cells and the microenvironment. In this contest, ion channels must be mentioned. Indeed, besides their canonical role in cell excitability, they can also modulate different cellular functions, such as proliferation, apoptosis and differentiation, in both excitable and non excitable cells. This role is also relevant in hematopoietic cells, where ion channels have a clear role in different functions of fully differentiated cells (Int Rev Cell Mol Biol. 2010;279:135–190). On these bases, we analyzed the role of ether a gò-gò-related gene 1 (ERG1) channels in normal hematopoiesis. In particular, we performed lack of function studies using a murine ERG1 knock out (KO) model (in SV129 strain). Since mice with a general and complete KO of the whole ERG1 gene die during early development, we analyzed mice with a selective deletion of the ERG1B isoform (ERG1B−/− mice, Mol Cell Biol. 1003;23(6):1856–1862), which is the ERG1 isoform mostly expressed in leukemic blasts (Blood. 2007;110(4):1238–1250). Such mice are viable and do not show any life threatening physical or behavioral abnormalities. First, we verified ERG1 transcripts expression in wild type SV129 mice (WT): both transcripts were expressed in spleen and thymus with higher values for the ERG1A isoform; ERG1B isoform presented a good expression level in bone marrow (BM) especially in the Sca-1+ population. Consequently we performed experiments to evaluate the role of ERG1B in normal hematopoiesis. Young (0–3 months old) KO mice presented a reduced number of CFUs (colony forming units) in the BM. CFUs levels were restored in adult mice. BM of KO mice showed hypocellularity and an increased number of megakaryocytes intriguingly associated with a reduction of erythrocytes (Ter119+). As evidenced by the histological analysis, splenomegaly of KO mice could be traced back to a great amount of mature red blood cells, filling the interfollicular space of the red pulp and subcapsulary space. Such splenic congestion in ERG1B−/− mice is accompanied by a relative decrease in the number of megakaryocytes, as well as by a reduced capacity to develop CFUs. On the whole, these data are suggestive of a failure of spleen hemopoiesis, with a concomitant red cell engulfment that lead to a putative erythropoiesis that occurs locally in the spleen maybe due to reprogrammation of hematopoietic cells of different lineage. To better characterize hematopoiesis in ERG1B−/− mouse model we performed two different stress tests: myelotoxicity and acute hemolytic anemia induction. Myelotoxicity was induced by single dose injection of cyclophosphamide (450 mg/Kg) in both WT and KO mice. From this induction we expected a decreased myelopoiesis, mostly affecting granulocytes and monocytes, followed by a rebound due to the capacity of the mice to undertake myelopoiesis. In KO model this compensation was absent suggesting a functional defect into the myeloid lineage correlated with ERG1B deletion. Finally, we induced acute anemia in mice testing their response to phenylhydrazine (PHZ, 60 mg/Kg). As expected, in WT mice, RBCs value rapidly declined followed by a compensatory erythropoiesis. In ERG1B−/− mice, we observed a reduced capacity to recover physiological RBCs values. Such results suggest that a functional defect occurred also into the erythroid lineage. On the whole, the present study provides evidence that the ERG1B isoform exerts a relevant role in hematopoiesis, driving the commitment and maturation of different hematopoietic cell populations. Disclosures: No relevant conflicts of interest to declare.

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