Voltage-dependent Anion Channel Function Research Articles

Establishing the role of the mitochondrial voltage-dependent anion channel (VDAC) in Trypanosoma cruzi.

The protozoan Trypanosoma cruzi is the causative agent of Chagas Disease, a neglected tropical disease that affects millions globally. As it transitions from insect vector to human host, T. cruzi faces homeostatic challenges, including oxidative stress, fluctuations in osmolarity, and nutrient availability. Ion channels regulate the parasite's ability to respond to environmental stressors. Our group has previously identified a mechanosensitive channel located in the contractile vacuole that, when knocked out, leads to reduced infectivity, abnormal morphology, and impaired motility. Transcriptomic analysis showed that Voltage-Dependent Anion Channel (VDAC) was significantly downregulated in the knockouts, suggesting a functional link between the two proteins. VDAC is a highly expressed outer mitochondrial membrane protein that, in other eukaryotes, regulates cell death, mitochondrial dynamics and metabolism. In protozoans, VDAC has been shown to share similar functions, with additional roles in tRNA and protein import. However, the function of VDAC in T. cruzi remains uncharacterized. The genome of T. cruzi contains five copies of VDAC sharing 99% homology. Four of them are organized in tandem, suggesting a gene expansion event as their most probable origin. To elucidate the function of this channel in the parasites, we targeted a conserved region using CRISPR/Cas9 strategies to generate a VDAC-deficient cell line. The mutant strain exhibited abnormal morphology and significant growth defects relative to the wild type, suggesting that VDAC is critical for parasite replication. Fluorometric analysis indicates that VDAC downregulation results in mitochondrial depolarization and reduced calcium uptake supporting its role in maintenance of mitochondrial functions.

VDAC interactions with lipids and their effect on isoform specificity.

The Voltage-Dependent Anion Channel (VDAC) is a β-barrel, the most abundant protein of the mitochondrial outer membrane, allowing passage of ions and metabolites (such as ATP, ADP, NADH⋯) in and out of the mitochondria. Besides its transport function, VDAC is also implicated in mitochondrial regulation with roles in apoptosis, calcium homeostasis or neurodegeneration. However, its role in those different pathways remains to be understood at the molecular level. VDAC possesses 3 isoforms in mammals (VDAC1, 2 and 3), sharing a high sequence identity, the same architecture and an overlapping tissue distribution. They display very similar transport properties such as conductance, selectivity and voltage-induced closure while their isoform specificity originates from their different interaction with partner proteins. This may determine their unique role in mitochondrial regulation, where each isoform seems to have different functions and a different set of partners: VDAC1 is implicated in neurodegeneration (Alzheimer and Parkinson disease), VDAC2 in apoptosis and calcium homeostasis, and VDAC3 probably in spermatogenesis and oxidative stress. Using a combination of biochemistry, molecular dynamics and electrophysiology, we investigated the lipid organization around each VDAC isoform and their impact on VDAC function. Our data suggest that the three isoforms have different affinities for lipids, and that could contribute to the selection of interacting partners.

Glutamate 73 Promotes Anti-arrhythmic Effects of Voltage-Dependent Anion Channel Through Regulation of Mitochondrial Ca2+ Uptake.

Mitochondria critically regulate a range of cellular processes including bioenergetics, cellular metabolism, apoptosis, and cellular Ca2+ signaling. The voltage-dependent anion channel (VDAC) functions as a passageway for the exchange of ions, including Ca2+, across the outer mitochondrial membrane. In cardiomyocytes, genetic or pharmacological activation of isoform 2 of VDAC (VDAC2) effectively potentiates mitochondrial Ca2+ uptake and suppresses Ca2+ overload-induced arrhythmogenic events. However, molecular mechanisms by which VDAC2 controls mitochondrial Ca2+ transport and thereby influences cardiac rhythmicity remain elusive. Vertebrates express three highly homologous VDAC isoforms. Here, we used the zebrafish tremblor/ncx1h mutant to dissect the isoform-specific roles of VDAC proteins in Ca2+ handling. We found that overexpression of VDAC1 or VDAC2, but not VDAC3, suppresses the fibrillation-like phenotype in zebrafish tremblor/ncx1h mutants. A chimeric approach showed that moieties in the N-terminal half of VDAC are responsible for their divergent functions in cardiac biology. Phylogenetic analysis further revealed that a glutamate at position 73, which was previously described to be an important regulator of VDAC function, is sevolutionarily conserved in VDAC1 and VDAC2, whereas a glutamine occupies position 73 (Q73) of VDAC3. To investigate whether E73/Q73 determines VDAC isoform-specific anti-arrhythmic effect, we mutated E73 to Q in VDAC2 (VDAC2E73Q) and Q73 to E in VDAC3 (VDAC3Q73E). Interestingly, VDAC2E73Q failed to restore rhythmic cardiac contractions in ncx1 deficient hearts, while the Q73E conversion induced a gain of function in VDAC3. In HL-1 cardiomyocytes, VDAC2 knockdown diminished the transfer of Ca2+ from the SR into mitochondria and overexpression of VDAC2 or VDAC3Q73E restored SR-mitochondrial Ca2+ transfer in VDAC2 deficient HL-1 cells, whereas this rescue effect was absent for VDAC3 and drastically compromised for VDAC2E73Q. Collectively, our findings demonstrate a critical role for the evolutionary conserved E73 in determining the anti-arrhythmic effect of VDAC isoforms through modulating Ca2+ cross-talk between the SR and mitochondria in cardiomyocytes.

Energy Metabolic Plasticity of Colorectal Cancer Cells as a Determinant of Tumor Growth and Metastasis.

Metabolic plasticity is the ability of the cell to adjust its metabolism to changes in environmental conditions. Increased metabolic plasticity is a defining characteristic of cancer cells, which gives them the advantage of survival and a higher proliferative capacity. Here we review some functional features of metabolic plasticity of colorectal cancer cells (CRC). Metabolic plasticity is characterized by changes in adenine nucleotide transport across the outer mitochondrial membrane. Voltage-dependent anion channel (VDAC) is the main protein involved in the transport of adenine nucleotides, and its regulation is impaired in CRC cells. Apparent affinity for ADP is a functional parameter that characterizes VDAC permeability and provides an integrated assessment of cell metabolic state. VDAC permeability can be adjusted via its interactions with other proteins, such as hexokinase and tubulin. Also, the redox conditions inside a cancer cell may alter VDAC function, resulting in enhanced metabolic plasticity. In addition, a cancer cell shows reprogrammed energy transfer circuits such as adenylate kinase (AK) and creatine kinase (CK) pathway. Knowledge of the mechanism of metabolic plasticity will improve our understanding of colorectal carcinogenesis.

Structure, gating and interactions of the voltage-dependent anion channel

The voltage-dependent anion channel (VDAC) is one of the most highly abundant proteins found in the outer mitochondrial membrane, and was one of the earliest discovered. Here we review progress in understanding VDAC function with a focus on its structure, discussing various models proposed for voltage gating as well as potential drug targets to modulate the channel’s function. In addition, we explore the sensitivity of VDAC structure to variations in the membrane environment, comparing DMPC-only, DMPC with cholesterol, and near-native lipid compositions, and use magic-angle spinning NMR spectroscopy to locate cholesterol on the outside of the β-barrel. We find that the VDAC protein structure remains unchanged in different membrane compositions, including conditions with cholesterol.

Do folding elements trade‐off with function in the human mitochondrial metabolite transporter?

In humans, transmembrane β‐barrels are found exclusively in the outer mitochondrial membrane (OMM). They comprise metabolite transporters, translocases, and chaperones, which together control cellular homeostasis. The metabolite transporters — known as voltage‐dependent anion channels (VDACs) – are the most abundant OMM barrels. They are 19‐stranded β‐barrel structures that also form important pharmacological targets due to their roles in metabolite flux, steroidogenesis, gametogenesis, and ROS regulation. Despite long‐standing efforts, molecular factors that regulate VDAC function and folding at the atomistic level are not known. Here, we map the folding nucleus and the assembly pathway of human VDAC isoform 2 in phosphocholine vesicles. We carry out a comprehensive measurement of hVDAC2 folding kinetics, and equilibrium thermodynamic contribution, of each of the 270 non‐Ala residues of the 294‐residue barrel. Interestingly, we obtain a two‐state thermodynamic equilibrium that is attained through two detectable on‐pathway early folding intermediates, which are assembled in milliseconds – seconds. These intermediates undergo slow conformational restructuring to form the folded VDAC2 barrel. We find that specific charged residues that form a part of these early intermediates also positively regulate the gating characteristics of VDAC2. This observation is unprecedented, as directed evolution of protein sequences in favor of function usually place a stability burden on its structure that additionally impedes protein assembly. Our findings provide molecular insight on the assembly pathway of human VDAC2, and directly link these folding elements with VDAC2 function as the metabolite transporter of human mitochondria.Support or Funding InformationThis work was supported by the Wellcome Trust/DBT India Alliance Fellowship [grant number IA/I/14/1/501305] awarded to RM.

Linking Folding Landscape with Function in the Human Mitochondrial VDAC2

Transmembrane β-barrels in humans are exclusive to the mitochondrial outer membrane (OMM). They include translocases, porins, and chaperones, which together regulate cellular homeostasis. The most abundant OMM proteins are the voltage-dependent anion channels (VDACs), which are 19-stranded multifunctional metabolite flux porins that are also important pharmacological targets. In humans, VDAC2 is anti-apoptotic and functions additionally in metabolite flux, steroidogenesis, gametogenesis, and ROS regulation, making this isoform indispensable for the cell. Despite long-standing efforts, molecular elements regulating VDAC function and folding are not known. Here, we map the folding nucleus and the assembly pathway of human VDAC2 in phosphocholine vesicles. We carry out a comprehensive measurement of folding kinetics and equilibrium thermodynamic contribution of each of the 270 non-Ala residues in the 294-residue barrel. Interestingly, we obtain a two-state thermodynamic equilibrium that is achieved through two detectable on-pathway early folding intermediates, which drive barrel assembly. Detailed analysis of the transition state structure reveals that specific strands at the N-terminal and central region of the barrel assemble first, which is followed by structuring of the C-terminal region. Residues causing frustration in the folding (Φ-value < 0) are more populated towards the C-terminal strands. Furthermore, specific charged residues that regulate the gating characteristics of human VDAC2 are surprisingly a part of the folding nucleus. The only interesting exception is D169, which is functionally important in vivo for cell survival, but establishes non-native contacts during VDAC2 folding. Relating our findings with the proposed mechanism of chaperone–assisted folding in the OMM provides molecular insight that links the assembly pathway of human VDAC2 with function.

Assessing the role of residue E73 and lipid headgroup charge in VDAC1 voltage gating

The voltage-dependent anion channel (VDAC) is the most abundant protein of the mitochondrial outer membrane (MOM) where it regulates transport of ions and metabolites in and out of the organelle. VDAC function is extensively studied in a lipid bilayer system that allows conductance monitoring of reconstituted channels under applied voltage. The process of switching from a high-conductance state, open to metabolites, to a variety of low-conducting states, which excludes metabolite transport, is termed voltage gating and the mechanism remains poorly understood. Recent studies have implicated the involvement of the membrane-solvated residue E73 in the gating process through β-barrel destabilization. However, there has been no direct experimental evidence of E73 involvement in VDAC1 voltage gating. Here, using electrophysiology measurements, we exclude the involvement of E73 in murine VDAC1 (mVDAC1) voltage gating process. With an established protocol of assessing voltage gating of VDACs reconstituted into planar lipid membranes, we definitively show that mVDAC1 gating properties do not change when E73 is replaced by either a glutamine or an alanine. We further demonstrate that cholesterol has no effect on mVDAC1 gating characteristics, though it was shown that E73 is coordinating residue in the cholesterol binding site. In contrast, we found a pronounced gating effect based on the charge of the phospholipid headgroup, where the positive charge stimulates and negative charge suppresses gating. These findings call for critical evaluation of the existing models of VDAC gating and contribute to our understanding of VDAC's role in control of MOM permeability and regulation of mitochondrial respiration and metabolism.

Evolution of Voltage-Dependent Anion Channel Function: From Molecular Sieve to Governator to Actuator of Ferroptosis.

The voltage-dependent anion channel (VDAC) is well known as the pathway for passive diffusion of anionic hydrophilic mitochondrial metabolites across the outer membrane, but a more complex functionality of the three isoforms of VDAC has emerged, as addressed in the Frontiers in Oncology Research Topic on “Uncovering the Function of the Mitochondrial Protein VDAC in Health and Disease: from Structure-Function to Novel Therapeutic Strategies.” VDAC as the single most abundant protein in mitochondrial outer membranes is typically involved in isoform-specific interactions of the mitochondrion with its surroundings as, for example, during mitochondria-dependent pathways of cell death. VDAC closure can also act as an adjustable limiter (governator) of global mitochondrial metabolism, as during hepatic ethanol metabolism to promote selective oxidation of membrane-permeant acetaldehyde. In cancer cells, high free tubulin inhibits VDAC1 and VDAC2, contributing to suppression of mitochondrial function in the Warburg phenomenon. Erastin, the canonical inducer of ferroptosis, opens VDAC in the presence of tubulin and hyperpolarizes mitochondria, leading to mitochondrial production of reactive oxygen species, mitochondrial dysfunction, and cell death. Our understanding of VDAC function continues to evolve.

Changes in the mitochondrial protein profile due to ROS eruption during ageing of elm (Ulmus pumila L.) seeds

Reactive oxygen species (ROS)-related mitochondrial dysfunction is considered to play a vital role in seed deterioration. However, the detailed mechanisms remain largely unknown. To address this, a comparison of mitochondrial proteomes was performed, and we identified several proteins that changed in abundance with accompanying ROS eruption and mitochondrial aggregation and diffusion. These are involved in mitochondrial metabolisms, stress resistance, maintenance of structure and intracellular transport during seed aging. Reduction of ROS content by the mitochondrial-specific scavenger MitoTEMPO suppressed these changes, whereas pre-treatment of seeds with methyl viologen (MV) had the opposite effect. Furthermore, voltage-dependent anion channels (VDAC) were found to increase both in abundance and carbonylation level, accompanied by increased cytochrome c (cyt c) release from mitochondria to cytosol, indicating the profound effect of ROS and VDAC on mitochondria-dependent cell death. Carbonylation detection revealed the specific target proteins of oxidative modification in mitochondria during ageing. Notably, membrane proteins accounted for a large proportion of these targets. An in vitro assay demonstrated that the oxidative modification was concomitant with a change of VDAC function and a loss of activity in malate dehydrogenase. Our data suggested that ROS eruption induced alteration and modification of specific mitochondrial proteins that may be involved in the process of mitochondrial deterioration, which eventually led to loss of seed viability.

Molecular Plasticity of the Human Voltage-Dependent Anion Channel Embedded Into a Membrane

The voltage-dependent anion channel (VDAC) regulates the flux of metabolites and ions across the outer mitochondrial membrane. Regulation of ion flow involves conformational transitions in VDAC, but the nature of these changes has not been resolved to date. By combining single-molecule force spectroscopy with nuclear magnetic resonance spectroscopy we show that the β barrel of human VDAC embedded into a membrane is highly flexible. Its mechanical flexibility exceeds by up to one order of magnitude that determined for β strands of other membrane proteins and is largest in the N-terminal part of the β barrel. Interaction with Ca(2+), a key regulator of metabolism and apoptosis, considerably decreases the barrel's conformational variability and kinetic free energy in the membrane. The combined data suggest that physiological VDAC function depends on the molecular plasticity of its channel.

Expression and purification of OsVDAC4.

The voltage-dependent anion channel (VDAC), a major component of the mitochondrial outer membrane, has emerged as an important player in cell function, survival, and death signaling. VDAC function is modulated by its interaction with proteins such as hexokinase, adenine nucleotide translocator, and apoptotic proteins like Bax. Monitoring the activity of VDAC and its modulation in the complex cellular milieu is fraught with complications. Minimizing the number of components in the study is one approach to teasing apart various aspects of its function. In this chapter, we have described detailed protocols for the purification of a rice VDAC isoform, OsVDAC4 after overexpression in a bacterial system. The protein is solubilized with LDAO and then reconstituted into liposomes or planar bilayers to verify its competence to fold into a functionally active form.

AB219. The use of anti-VDAC2 antibody for the combined assessment of human sperm acrosome integrity and ionophore A23187-induced acrosome reaction

Voltage-dependent anion channel (VDAC) is mainly located in the mitochondrial outer membrane and participates in many biological processes. In mammals, three VDAC subtypes (VDAC1, 2 and 3) have been identified. Although VDAC has been extensively studied in various tissues and cells, there is little knowledge about the distribution and function of VDAC in male mammalian reproductive system. Several studies have demonstrated that VDAC exists in mammalian spermatozoa and is implicated in spermatogenesis, sperm maturation, motility and fertilization. However, there is no knowledge about the respective localization and function of three VDAC subtypes in human spermatozoa. In this study, we focused on the presence of VDAC2 in human spermatozoa and its possible role in the acrosomal integrity and acrosome reaction using specific anti-VDAC2 monoclonal antibody for the first time. The results exhibited that native VDAC2 existed in the membrane components of human spermatozoa. The co-incubation of spermatozoa with anti-VDAC2 antibody did not affect the acrosomal integrity and acrosome reaction, but inhibited ionophore A23187-induced intracellular Ca increase. Our study suggested that VDAC2 was located in the acrosomal membrane or plasma membrane of human spermatozoa, and played putative roles in sperm functions through mediating Ca transmembrane transport.

Computational investigation of cholesterol binding sites on mitochondrial VDAC.

The mitochondrial voltage-dependent anion channel (VDAC) allows passage of ions and metabolites across the mitochondrial outer membrane. Cholesterol binds mammalian VDAC, and we investigated the effects of binding to human VDAC1 with atomistic molecular dynamics simulations that totaled 1.4 μs. We docked cholesterol to specific sites on VDAC that were previously identified with NMR, and we tested the reliability of multiple docking results in each site with simulations. The most favorable binding modes were used to build a VDAC model with cholesterol occupying five unique sites, and during multiple 100 ns simulations, cholesterol stably and reproducibly remained bound to the protein. For comparison, VDAC was simulated in systems with identical components but with cholesterol initially unbound. The dynamics of loops that connect adjacent β-strands were most affected by bound cholesterol, with the averaged root-mean-square fluctuation (RMSF) of multiple residues altered by 20–30%. Cholesterol binding also stabilized charged residues inside the channel and localized the surrounding electrostatic potentials. Despite this, ion diffusion through the channel was not significantly affected by bound cholesterol, as evidenced by multi-ion potential of mean force measurements. Although we observed modest effects of cholesterol on the open channel, our model will be particularly useful in experiments that investigate how cholesterol affects VDAC function under applied electrochemical forces and also how other ligands and proteins interact with the channel.

S.27.01 Mitochondria and Aβ metabolism

Regulation of mitochondrial outer membrane (MOM) permeability has dual importance: in normal metabolite and energy exchange between mitochondria and cytoplasm, and thus in control of respiration, and in apoptosis by release of apoptogenic factors into the cytosol. However, the mechanism of this regulation involving the voltage-dependent anion channel (VDAC), the major channel of MOM, remains controversial. For example, one of the long-standing puzzles was that in permeabilized cells, adenine nucleotide translocase is less accessible to cytosolic ADP than in isolated mitochondria. Still another puzzle was that, according to channel-reconstitution experiments, voltage regulation of VDAC is limited to potentials exceeding 30 mV, which are believed to be much too high for MOM. We have solved these puzzles and uncovered multiple new functional links by identifying a missing player in the regulation of VDAC and, hence, MOM permeability — the cytoskeletal protein tubulin. We have shown that, depending on VDAC phosphorylation state and applied voltage, nanomolar to micromolar concentrations of dimeric tubulin induce functionally important reversible blockage of VDAC reconstituted into planar phospholipid membranes. The voltage sensitivity of the blockage equilibrium is truly remarkable. It is described by an effective “gating charge” of more than ten elementary charges, thus making the blockage reaction as responsive to the applied voltage as the most voltage-sensitive channels of electrophysiology are. Analysis of the tubulin-blocked state demonstrated that although this state is still able to conduct small ions, it is impermeable to ATP and other multi-charged anions because of the reduced aperture and inversed selectivity. The findings, obtained in a channel reconstitution assay, were supported by experiments with isolated mitochondria and human hepatoma cells. Taken together, these results suggest a previously unknown mechanism of regulation of mitochondrial energetics, governed by VDAC interaction with tubulin at the mitochondria–cytosol interface. Immediate physiological implications include new insights into serine/threonine kinase signaling pathways, Ca2 + homeostasis, and cytoskeleton/microtubule activity in health and disease, especially in the case of the highly dynamic microtubule network which is characteristic of cancerogenesis and cell proliferation. In the present review, we speculate how these findings may help to identify new mechanisms of mitochondria-associated action of chemotherapeutic microtubule-targeting drugs, and also to understand why and how cancer cells preferentially use inefficient glycolysis rather than oxidative phosphorylation (Warburg effect). This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.

Evidence for a relation between plasma membrane coenzyme Q and autism

Voltage Dependent Anion Channel (VDAC) in the cell membrane transports important molecules and ions across the cell membrane. It was recently shown that VDAC also acts as a trans membrane NADH dehydrogenase. A recent study showed that autistic children have increased antibodies to VDAC proteins and such a binding inhibits both the transport and dehydrogenase activities of VDAC. The derived function of VDAC, therefore, might underlie the development of autism. It has also recently been shown that the dehydrogenase in erythrocyte membranes requires coenzyme Q. Since the plasma membrane oxidase is not in erythrocyte membranes, the coenzyme Q requirement must be for VDAC. This is consistent with sensitivity of the dehydrogenase to SH inhibitors. This is a novel site for coenzyme Q function but it has an analogy with the Q requirement for the mitochondrial uncoupler protein and the permeability transition pore.

Solution NMR spectroscopic characterization of human VDAC-2 in detergent micelles and lipid bilayer nanodiscs

Three isoforms of the human voltage-dependent anion channel (VDAC), located in the outer mitochondrial membrane, are crucial regulators of mitochondrial function. Numerous studies have been carried out to elucidate biochemical properties, as well as the three-dimensional structure of VDAC-1. However, functional and structural studies of VDAC-2 and VDAC-3 at atomic resolution are still scarce. VDAC-2 is highly similar to VDAC-1 in amino acid sequence, but has substantially different biochemical functions and expression profiles. Here, we report the reconstitution of functional VDAC-2 in lauryldimethylamine-oxide (LDAO) detergent micelles and 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) lipid bilayer nanodiscs. We find that VDAC-2 is properly folded in both membrane-mimicking systems and that structural and functional characterization by solution NMR spectroscopy is feasible. This article is part of a Special Issue entitled: VDAC structure, function, and regulation of mitochondrial metabolism.

Molecular and genetic characterization of the gene family encoding the voltage-dependent anion channel in Arabidopsis

The voltage-dependent anion channel (VDAC), a major outer mitochondrial membrane protein, is thought to play an important role in energy production and apoptotic cell death in mammalian systems. However, the function of VDACs in plants is largely unknown. In order to determine the individual function of plant VDACs, molecular and genetic analysis was performed on four VDAC genes, VDAC1–VDAC4, found in Arabidopsis thaliana. VDAC1 and VDAC3 possess the eukaryotic mitochondrial porin signature (MPS) in their C-termini, while VDAC2 and VDAC4 do not. Localization analysis of VDAC–green fluorescent protein (GFP) fusions and their chimeric or mutated derivatives revealed that the MPS sequence is important for mitochondrial localization. Through the functional analysis of vdac knockout mutants due to T-DNA insertion, VDAC2 and VDAC4 which are expressed in the whole plant body are important for various physiological functions such as leaf development, the steady state of the mitochondrial membrane potential, and pollen development. Moreover, it was demonstrated that VDAC1 is not only necessary for normal growth but also important for disease resistance through regulation of hydrogen peroxide generation.

The Use of Anti-VDAC2 Antibody for the Combined Assessment of Human Sperm Acrosome Integrity and Ionophore A23187-Induced Acrosome Reaction

Voltage-dependent anion channel (VDAC) is mainly located in the mitochondrial outer membrane and participates in many biological processes. In mammals, three VDAC subtypes (VDAC1, 2 and 3) have been identified. Although VDAC has been extensively studied in various tissues and cells, there is little knowledge about the distribution and function of VDAC in male mammalian reproductive system. Several studies have demonstrated that VDAC exists in mammalian spermatozoa and is implicated in spermatogenesis, sperm maturation, motility and fertilization. However, there is no knowledge about the respective localization and function of three VDAC subtypes in human spermatozoa. In this study, we focused on the presence of VDAC2 in human spermatozoa and its possible role in the acrosomal integrity and acrosome reaction using specific anti-VDAC2 monoclonal antibody for the first time. The results exhibited that native VDAC2 existed in the membrane components of human spermatozoa. The co-incubation of spermatozoa with anti-VDAC2 antibody did not affect the acrosomal integrity and acrosome reaction, but inhibited ionophore A23187-induced intracellular Ca2+ increase. Our study suggested that VDAC2 was located in the acrosomal membrane or plasma membrane of human spermatozoa, and played putative roles in sperm functions through mediating Ca2+ transmembrane transport.

Mitochondrial ROS fuel the inflammasome

Mitochondrial ROS fuel the inflammasome