scholarly journals Voltage-Gated Proton Channels Exist in the Plasma Membrane of Human Oocytes

2020 ◽  
Vol 118 (3) ◽  
pp. 275a
Author(s):  
Thomas E. DeCoursey
Keyword(s):  
Plasma Membrane ◽  
Human Oocytes ◽  
Proton Channels ◽  
Voltage Gated

scholarly journals Voltage-gated proton channels exist in the plasma membrane of human oocytes

2019 ◽  
Vol 34 (10) ◽  
pp. 1974-1983 ◽  
Author(s):  
R Ya Smith ◽  
D Morgan ◽  
L Sharma ◽  
V V Cherny ◽  
N Tidswell ◽  
...  
Keyword(s):  
Large Scale ◽  
Human Sperm ◽  
Proton Channel ◽  
Human Oocytes ◽  
Proton Channels ◽  
Voltage Gated ◽  
Registration Number ◽  
Heterologous Expression Systems ◽  
Competing Interest ◽  
Proton Currents

Abstract STUDY QUESTION Do human oocytes express voltage-gated proton channels? SUMMARY ANSWER Human oocytes exhibit voltage-gated proton currents. WHAT IS KNOWN ALREADY Voltage-gated proton currents have been reported in human sperm, where they contribute to capacitation and motility. No such studies of human oocytes exist. STUDY DESIGN, SIZE, DURATION Voltage-clamp studies were undertaken using entire oocytes and vesicles derived from oocytes and in excised patches of membrane from oocytes. PARTICIPANTS/MATERIALS, SETTING, METHODS Frozen, thawed human metaphase II oocytes were obtained from material donated to the gamete repository at the Rush Center for Advanced Reproductive Care. Prior to patch clamping, oocytes were warmed and equilibrated. Formation of an electrically tight seal requires exposing bare oolemma. Sections of the zona pellucida (ZP) were removed using a laser, followed by repeated pipetting, to further separate the oocyte from the ZP. Patch-clamp studies were performed using the whole-cell configuration on oocytes or vesicles derived from oocytes, and using inside-out patches of membrane, under conditions optimized to detect voltage-gated proton currents. MAIN RESULTS AND THE ROLE OF CHANCE Proton currents are present at significant levels in human oocytes where they exhibit properties similar to those reported in other human cells, as well as those in heterologous expression systems transfected with the HVCN1 gene that codes for the voltage-gated proton channel. LARGE SCALE DATA N/A LIMITATIONS, REASONS FOR CAUTION Human oocytes are large cells, which limits our ability to control the intracellular solution. Subtle effects of cryopreservation by vitrification and subsequent warming on properties of HVCN1, the HVCN1 gene product, cannot be ruled out. WIDER IMPLICATIONS OF THE FINDINGS Possible functions for voltage-gated proton channels in human oocytes may now be contemplated. STUDY FUNDING/COMPETING INTEREST(S) NIH R35GM126902 (TED), Bears Care (DM). No competing interests. TRIAL REGISTRATION NUMBER N/A.

scholarly journals Roles of Microglial Ion Channel in Neurodegenerative Diseases

2021 ◽  
Vol 10 (6) ◽  
pp. 1239
Author(s):  
Alexandru Cojocaru ◽  
Emilia Burada ◽  
Adrian-Tudor Bălșeanu ◽  
Alexandru-Florian Deftu ◽  
Bogdan Cătălin ◽  
...  
Keyword(s):  
Ion Channels ◽  
Neurodegenerative Diseases ◽  
Excitable Cells ◽  
Proton Channels ◽  
Voltage Gated ◽  
Cellular Processes ◽  
Pathological Conditions ◽  
The Common ◽  
Transient Receptor ◽  
The Impact

As the average age and life expectancy increases, the incidence of both acute and chronic central nervous system (CNS) pathologies will increase. Understanding mechanisms underlying neuroinflammation as the common feature of any neurodegenerative pathology, we can exploit the pharmacology of cell specific ion channels to improve the outcome of many CNS diseases. As the main cellular player of neuroinflammation, microglia play a central role in this process. Although microglia are considered non-excitable cells, they express a variety of ion channels under both physiological and pathological conditions that seem to be involved in a plethora of cellular processes. Here, we discuss the impact of modulating microglia voltage-gated, potential transient receptor, chloride and proton channels on microglial proliferation, migration, and phagocytosis in neurodegenerative diseases.

scholarly journals The Antibacterial Activity of Human Neutrophils and Eosinophils Requires Proton Channels but Not BK Channels

2006 ◽  
Vol 127 (6) ◽  
pp. 659-672 ◽  
Author(s):  
Jon K. Femling ◽  
Vladimir V. Cherny ◽  
Deri Morgan ◽  
Balázs Rada ◽  
A. Paige Davis ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Respiratory Burst ◽  
Essential Role ◽  
Outward Current ◽  
Bk Channels ◽  
Bk Channel ◽  
Human Neutrophils ◽  
H2o2 Production ◽  
Proton Channels ◽  
Voltage Gated

Electrophysiological events are of central importance during the phagocyte respiratory burst, because NADPH oxidase is electrogenic and voltage sensitive. We investigated the recent suggestion that large-conductance, calcium-activated K+ (BK) channels, rather than proton channels, play an essential role in innate immunity (Ahluwalia, J., A. Tinker, L.H. Clapp, M.R. Duchen, A.Y. Abramov, S. Page, M. Nobles, and A.W. Segal. 2004. Nature. 427:853–858). In PMA-stimulated human neutrophils or eosinophils, we did not detect BK currents, and neither of the BK channel inhibitors iberiotoxin or paxilline nor DPI inhibited any component of outward current. BK inhibitors did not inhibit the killing of bacteria, nor did they affect NADPH oxidase-dependent degradation of bacterial phospholipids by extracellular gIIA-PLA2 or the production of superoxide anion (\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{O}_{2^{.}}^{{-}}\) \end{document}). Moreover, an antibody against the BK channel did not detect immunoreactive protein in human neutrophils. A required role for voltage-gated proton channels is demonstrated by Zn2+ inhibition of NADPH oxidase activity assessed by H2O2 production, thus validating previous studies showing that Zn2+ inhibited \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(\mathrm{O}_{2^{.}}^{{-}}\) \end{document} production when assessed by cytochrome c reduction. In conclusion, BK channels were not detected in human neutrophils or eosinophils, and BK inhibitors did not impair antimicrobial activity. In contrast, we present additional evidence that voltage-gated proton channels serve the essential role of charge compensation during the respiratory burst.

Voltage-gated proton channels help regulate pHi in rat alveolar epithelium

2005 ◽  
Vol 288 (2) ◽  
pp. L398-L408 ◽  
Author(s):  
Ricardo Murphy ◽  
Vladimir V. Cherny ◽  
Deri Morgan ◽  
Thomas E. DeCoursey
Keyword(s):  
Epithelial Cells ◽  
Ph Regulation ◽  
Alveolar Epithelial Cell ◽  
Alveolar Epithelium ◽  
Alveolar Epithelial Cells ◽  
Proton Channel ◽  
Resting Cells ◽  
Proton Channels ◽  
Voltage Gated ◽  
Alveolar Epithelial

Voltage-gated proton channels are expressed highly in rat alveolar epithelial cells. Here we investigated whether these channels contribute to pH regulation. The intracellular pH (pHi) was monitored using BCECF in cultured alveolar epithelial cell monolayers and found to be 7.13 in nominally HCO3−-free solutions [at external pH (pHo) 7.4]. Cells were acid-loaded by the NH4+ prepulse technique, and the recovery was observed. Under conditions designed to eliminate the contribution of other transporters that alter pH, addition of 10 μM ZnCl2, a proton channel inhibitor, slowed recovery about twofold. In addition, the pHi minimum was lower, and the time to nadir was increased. Slowing of recovery by ZnCl2 was observed at pHo 7.4 and pHo 8.0 and in normal and high-K+ Ringer solutions. The observed rate of Zn2+-sensitive pHi recovery required activation of a small fraction of the available proton conductance. We conclude that proton channels contribute to pHi recovery after an acid load in rat alveolar epithelial cells. Addition of ZnCl2 had no effect on pHi in unchallenged cells, consistent with the expectation that proton channels are not open in resting cells. After inhibition of all known pH regulators, slow pHi recovery persisted, suggesting the existence of a yet-undefined acid extrusion mechanism in these cells.

Autoimmune disorder phenotypes in Hvcn1-deficient mice

2013 ◽  
Vol 450 (2) ◽  
pp. 295-301 ◽  
Author(s):  
Mari Sasaki ◽  
Akihiro Tojo ◽  
Yoshifumi Okochi ◽  
Nana Miyawaki ◽  
Daisuke Kamimura ◽  
...  
Keyword(s):  
T Cells ◽  
Autoimmune Disorder ◽  
Whole Body ◽  
Activated T Cells ◽  
Proton Channels ◽  
Voltage Gated ◽  
In The Wild ◽  
Body Level ◽  
Deficient Mice

Hv channels (voltage-gated proton channels) are expressed in blood cells, microglia and some types of epithelial cells. In neutrophils Hv channels regulate the production of reactive oxygen species through regulation of membrane potential and intracellular pH. Hv channels have also been suggested to play a role in sperm physiology in the human. However, the functions of the Hv channel at the whole-body level are not fully understood. In the present paper we show that Hvcn1 (voltage-gated hydrogen channel 1)-knockout mice show splenomegaly, autoantibodies and nephritis, that are reminiscent of human autoimmune diseases phenotypes. The number of activated T-cells was larger in Hvcn1-deficient mice than in the wild-type mice. Upon viral infection this was remarkably enhanced in Hvcn1-deficient mice. The production of superoxide anion in T-cells upon stimulation with PMA was significantly attenuated in the Hvcn1-deficient mice. These results suggest that Hv channels regulate T-cell homoeostasis in vivo.

scholarly journals Inhibition of voltage-gated proton channels by local anaesthetics in GMI-R1 rat microglia

2012 ◽  
Vol 590 (4) ◽  
pp. 827-844 ◽  
Author(s):  
Tadashi Matsuura ◽  
Takashi Mori ◽  
Megumi Hasaka ◽  
Miyuki Kuno ◽  
Junko Kawawaki ◽  
...  
Keyword(s):  
Local Anaesthetics ◽  
Proton Channels ◽  
Voltage Gated

scholarly journals Axons provide the secretory machinery for trafficking of voltage-gated sodium channels in peripheral nerve

2016 ◽  
Vol 113 (7) ◽  
pp. 1823-1828 ◽  
Author(s):  
Carolina González ◽  
José Cánovas ◽  
Javiera Fresno ◽  
Eduardo Couve ◽  
Felipe A. Court ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Sodium Channel ◽  
Sodium Channels ◽  
Neural Function ◽  
Axonal Membrane ◽  
Local Synthesis ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels

The regulation of the axonal proteome is key to generate and maintain neural function. Fast and slow axoplasmic waves have been known for decades, but alternative mechanisms to control the abundance of axonal proteins based on local synthesis have also been identified. The presence of the endoplasmic reticulum has been documented in peripheral axons, but it is still unknown whether this localized organelle participates in the delivery of axonal membrane proteins. Voltage-gated sodium channels are responsible for action potentials and are mostly concentrated in the axon initial segment and nodes of Ranvier. Despite their fundamental role, little is known about the intracellular trafficking mechanisms that govern their availability in mature axons. Here we describe the secretory machinery in axons and its contribution to plasma membrane delivery of sodium channels. The distribution of axonal secretory components was evaluated in axons of the sciatic nerve and in spinal nerve axons after in vivo electroporation. Intracellular protein trafficking was pharmacologically blocked in vivo and in vitro. Axonal voltage-gated sodium channel mRNA and local trafficking were examined by RT-PCR and a retention-release methodology. We demonstrate that mature axons contain components of the endoplasmic reticulum and other biosynthetic organelles. Axonal organelles and sodium channel localization are sensitive to local blockade of the endoplasmic reticulum to Golgi transport. More importantly, secretory organelles are capable of delivering sodium channels to the plasma membrane in isolated axons, demonstrating an intrinsic capacity of the axonal biosynthetic route in regulating the axonal proteome in mammalian axons.

scholarly journals Ca2+-Dependent, Stimulus-Specific Modulation of the Plasma Membrane Ca2+ Pump in Hippocampal Neurons

2009 ◽  
Vol 101 (5) ◽  
pp. 2563-2571 ◽  
Author(s):  
Michael J. Ferragamo ◽  
Jessica L. Reinardy ◽  
Stanley A. Thayer
Keyword(s):  
Plasma Membrane ◽  
Neuronal Activity ◽  
Action Potentials ◽  
Hippocampal Neurons ◽  
Cyclopiazonic Acid ◽  
Synaptic Activity ◽  
Voltage Gated ◽  
Clearance Kinetics ◽  
Transient Elevation ◽  
Kinetics Of

The plasma membrane Ca2+ ATPase (PMCA) plays a major role in restoring Ca2+ to basal levels following transient elevation by neuronal activity. Here we examined the effects of various stimuli that increase [Ca2+]i on PMCA-mediated Ca2+ clearance from hippocampal neurons. We used indo-1-based microfluorimetry in the presence of cyclopiazonic acid to study the rate of PMCA-mediated recovery of Ca2+ elevated by a brief train of action potentials. [Ca2+]i recovery was described by an exponential decay and the time constant provided an index of PMCA-mediated Ca2+ clearance. PMCA function was assessed before and for ≥60 min following a 10-min priming stimulus of either 100 μM N-methyl-d-aspartate (NMDA), 0.1 mM Mg2+ (reduced extracellular Mg2+ induces intense excitatory synaptic activity), 30 mM K+, or control buffer. Recovery kinetics slowed progressively following priming with NMDA or 0.1 mM Mg2+; in contrast, Ca2+ clearance initially accelerated and then slowly returned to initial rates following priming with 30 mM K+-induced depolarization. Treatment with 10 μM calpeptin, an inhibitor of the Ca2+ activated protease calpain, prevented the slowing of kinetics observed following treatment with NMDA but had no affect on the recovery kinetics of control cells. Calpeptin also blocked the rapid acceleration of Ca2+ clearance following depolarization. In calpeptin-treated cells, 0.1 mM Mg2+ induced a graded acceleration of Ca2+ clearance. Thus in spite of producing comparable increases in [Ca2+]i, activation of NMDA receptors, depolarization-induced activation of voltage-gated Ca2+ channels and excitatory synaptic activity each uniquely affected Ca2+ clearance kinetics mediated by the PMCA.

Sign in / Sign up

Export Citation Format

Share Document