Spatial cognitive deficits in an animal model of Wernicke–Korsakoff syndrome are related to changes in thalamic VDAC protein concentrations

AMPK/PGC-1α and p53 modulate VDAC1 expression mediated by reduced ATP level and metabolic oxidative stress in neuronal cells

Voltage-dependent anion channel 1 (VDAC1) is a pore protein located in the outer mitochondrial membrane. Its channel gating mediates mitochondrial respiration and cell metabolism, and it has been identified as a critical modulator of mitochondria-mediated apoptosis. In many diseases characterized by mitochondrial dysfunction, such as cancer and neurodegenerative diseases, VDAC1 is considered a promising potential therapeutic target. However, there is limited research on the regulatory factors involved in VDAC1 protein expression in both normal and pathological states. In this study, we find that VDAC1 protein expression is up-regulated in various neuronal cell lines in response to intracellular metabolic and oxidative stress. We further demonstrate that VDAC1 expression is modulated by intracellular ATP level. Through the use of pharmacological agonists and inhibitors and small interfering RNA (siRNA), we reveal that the AMPK/PGC-1α signaling pathway is involved in regulating VDAC1 expression. Additionally, based on bioinformatics predictions and biochemical verification, we identify p53 as a potential transcription factor that regulates VDAC1 promoter activity during metabolic oxidative stress. Our findings suggest that VDAC1 expression is regulated by the AMPK/PGC-1α and p53 pathways, which contributes to the maintenance of stress adaptation and apoptotic homeostasis in neuronal cells.

Targeting the overexpressed mitochondrial protein VDAC1 in a mouse model of Alzheimer's disease protects against mitochondrial dysfunction and mitigates brain pathology

BACKGROUND

Alzheimer's disease (AD) exhibits mitochondrial dysfunctions associated with dysregulated metabolism, brain inflammation, synaptic loss, and neuronal cell death. As a key protein serving as the mitochondrial gatekeeper, the voltage-dependent anion channel-1 (VDAC1) that controls metabolism and Ca²⁺ homeostasis is positioned at a convergence point for various cell survival and death signals. Here, we targeted VDAC1 with VBIT-4, a newly developed inhibitor of VDAC1 that prevents its pro-apoptotic activity, and mitochondria dysfunction.

METHODS

To address the multiple pathways involved in AD, neuronal cultures and a 5 × FAD mouse model of AD were treated with VBIT-4. We addressed multiple topics related to the disease and its molecular mechanisms using immunoblotting, immunofluorescence, q-RT-PCR, 3-D structural analysis and several behavioral tests.

RESULTS

In neuronal cultures, amyloid-beta (Aβ)-induced VDAC1 and p53 overexpression and apoptotic cell death were prevented by VBIT-4. Using an AD-like 5 × FAD mouse model, we showed that VDAC1 was overexpressed in neurons surrounding Aβ plaques, but not in astrocytes and microglia, and this was associated with neuronal cell death. VBIT-4 prevented the associated pathophysiological changes including neuronal cell death, neuroinflammation, and neuro-metabolic dysfunctions. VBIT-4 also switched astrocytes and microglia from being pro-inflammatory/neurotoxic to neuroprotective phenotype. Moreover, VBIT-4 prevented cognitive decline in the 5 × FAD mice as evaluated using several behavioral assessments of cognitive function. Interestingly, VBIT-4 protected against AD pathology, with no significant change in phosphorylated Tau and only a slight decrease in Aβ-plaque load.

CONCLUSIONS

The study suggests that mitochondrial dysfunction with its gatekeeper VDAC1 is a promising target for AD therapeutic intervention, and VBIT-4 is a promising drug candidate for AD treatment.

VDAC1 regulates neuronal cell loss after retinal trauma injury by a mitochondria-independent pathway

The voltage-dependent anion channel 1 (VDAC1) was first described as a mitochondrial porin that mediates the flux of metabolites and ions, thereby integrating both cell survival and death signals. In the nervous system, the functional roles of VDAC1 remain poorly understood. Herein, the rat retina was employed to study VDAC1. First, it was observed that even subtle changes in VDAC1 levels affect neuronal survival, inducing severe alterations in the retinal morphology. We next examined the regulation of VDAC1 after traumatic retinal injury. After mechanical trauma, SOD1 translocates towards the nucleus, which is insufficient to contain the consequences of oxidative stress, as determined by the evaluation of protein carbonylation. Using in vitro models of oxidative stress and mechanical injury in primary retinal cell cultures, it was possible to determine that inhibition of VDAC1 oligomerization by 4'-diisothiocyano-2,2'-disulfonic acid stilbene (DIDS) rescues cell viability, impacting microglial cell activation. We next focused on the regulation of VDAC1 after retinal mechanical injury. VDAC1 was promptly upregulated 2 h after lesion in the plasma membrane and endoplasmic reticulum rather than in the mitochondria, and multimers of VDAC1 were assembled after lesion. DIDS intraocular application decreased apoptosis and prevented microglial polarization, which confirmed in vitro observations. Considering the role of microglia in neuroinflammation, multiplex evaluation of cytokines showed that DIDS application disorganized the inflammatory response 2 h after the lesion, matching the fast regulation of VDAC1. Taken together, data disclosed that fine regulation of VDAC1 influences neuronal survival, and pharmacological inhibition after trauma injury has neuroprotective effects. This protection may be attributed to the effects on VDAC1 abnormal accumulation in the plasma membrane, thereby controlling the activation of microglial cells. We concluded that VDAC1 is a putative therapeutic target in neuronal disorders since it integrates both death and survival cellular signaling.

Adverse Effects of Metformin From Diabetes to COVID-19, Cancer, Neurodegenerative Diseases, and Aging: Is VDAC1 a Common Target?

Metformin has been used for treating diabetes mellitus since the late 1950s. In addition to its antihyperglycemic activity, it was shown to be a potential drug candidate for treating a range of other diseases that include various cancers, cardiovascular diseases, diabetic kidney disease, neurodegenerative diseases, renal diseases, obesity, inflammation, COVID-19 in diabetic patients, and aging. In this review, we focus on the important aspects of mitochondrial dysfunction in energy metabolism and cell death with their gatekeeper VDAC1 (voltage-dependent anion channel 1) as a possible metformin target, and summarize metformin’s effects in several diseases and gut microbiota. We question how the same drug can act on diseases with opposite characteristics, such as increasing apoptotic cell death in cancer, while inhibiting it in neurodegenerative diseases. Interestingly, metformin’s adverse effects in many diseases all show VDAC1 involvement, suggesting that it is a common factor in metformin-affecting diseases. The findings that metformin has an opposite effect on various diseases are consistent with the fact that VDAC1 controls cell life and death, supporting the idea that it is a target for metformin.

Altered insulin pathway compromises mitochondrial function and quality control both in in vitro and in vivo model systems

Altered insulin signaling and insulin resistance are considered the link between Alzheimer's disease (AD) and metabolic syndrome. Here, by using an in vitro and an in vivo model, we investigated the relationship between these disorders focusing on neuronal mitochondrial dysfunction and mitophagy. In vitro Aβ insult induced the opening of mitochondrial permeability transition pore (mPTP), mitochondrial membrane potential (ΔΨm) loss, and apoptosis while insulin addition ameliorated these dysfunctions. The same alterations were detected in a 16 weeks of age mouse model of diet-induced obesity and insulin resistance. In addition, we detected an increase of fission related proteins and activation of mitophagy, proved by the rise of PINK1 and Parkin proteins. Nevertheless, in vitro, the increase of p62 and LC3 indicated an alteration in autophagy, while, in vivo decreased expression of p62 and increase of LC3 suggested removing of damaged mitochondria. Finally, in aged mice (28 and 48 weeks), the data indicated impairment of mitophagy and suggested the accumulation of damaged mitochondria. Taken together these outcomes indicate that alteration of the insulin pathway affects mitochondrial integrity, and effective mitophagy is age-dependent.

Collective Dynamics of Ion Channels on Bilayer Lipid Membranes

Ion channels self-organize on cellular and organelle membranes as clusters and mutually modulate their gating behavior. It has been reported that the efficient information transfer is achieved by cooperative clustering of ion channels. To address the origin and nature of collective dynamics in ion channel clusters, a statistical mechanical model, namely, the Zimm-Bragg-type model in two dimensions with unequal weight distribution in channel-channel interactions, has been proposed. Nearest neighbor interaction along with next-nearest neighbor interaction has been considered, assuming symmetric spatial organization. The multichannel bilayer electrophysiology recordings of the voltage-dependent anion channel (VDAC) from rat brain mitochondria have been analyzed in order to test and further extend the model. The model successfully describes the multichannel gating behavior and self-organization of the VDAC cluster.

VDAC1 at the Intersection of Cell Metabolism, Apoptosis, and Diseases

The voltage-dependent anion channel 1 (VDAC1) protein, is an important regulator of mitochondrial function, and serves as a mitochondrial gatekeeper, with responsibility for cellular fate. In addition to control over energy sources and metabolism, the protein also regulates epigenomic elements and apoptosis via mediating the release of apoptotic proteins from the mitochondria. Apoptotic and pathological conditions, as well as certain viruses, induce cell death by inducing VDAC1 overexpression leading to oligomerization, and the formation of a large channel within the VDAC1 homo-oligomer. This then permits the release of pro-apoptotic proteins from the mitochondria and subsequent apoptosis. Mitochondrial DNA can also be released through this channel, which triggers type-Ι interferon responses. VDAC1 also participates in endoplasmic reticulum (ER)-mitochondria cross-talk, and in the regulation of autophagy, and inflammation. Its location in the outer mitochondrial membrane, makes VDAC1 ideally placed to interact with over 100 proteins, and to orchestrate the interaction of mitochondrial and cellular activities through a number of signaling pathways. Here, we provide insights into the multiple functions of VDAC1 and describe its involvement in several diseases, which demonstrate the potential of this protein as a druggable target in a wide variety of pathologies, including cancer.

VDAC1 functions in Ca2+ homeostasis and cell life and death in health and disease

In the outer mitochondrial membrane (OMM), the voltage-dependent anion channel 1 (VDAC1) serves as a mitochondrial gatekeeper, controlling the metabolic and energy cross-talk between mitochondria and the rest of the cell. VDAC1 also functions in cellular Ca²⁺ homeostasis by transporting Ca²⁺ in and out of mitochondria. VDAC1 has also been recognized as a key protein in mitochondria-mediated apoptosis, contributing to the release of apoptotic proteins located in the inter-membranal space (IMS) and regulating apoptosis via association with pro- and anti-apoptotic members of the Bcl-2 family of proteins and hexokinase. VDAC1 is highly Ca²⁺-permeable, transporting Ca²⁺ to the IMS and thus modulating Ca²⁺ access to Ca²⁺ transporters in the inner mitochondrial membrane. Intra-mitochondrial Ca²⁺ controls energy metabolism via modulating critical enzymes in the tricarboxylic acid cycle and in fatty acid oxidation. Ca²⁺ also determines cell sensitivity to apoptotic stimuli and promotes the release of pro-apoptotic proteins. However, the precise mechanism by which intracellular Ca²⁺ mediates apoptosis is not known. Here, the roles of VDAC1 in mitochondrial Ca²⁺ homeostasis are presented while emphasizing a new proposed mechanism for the mode of action of pro-apoptotic drugs. This view, proposing that Ca²⁺-dependent enhancement of VDAC1 expression levels is a major mechanism by which apoptotic stimuli induce apoptosis, position VDAC1 oligomerization at a molecular focal point in apoptosis regulation. The interactions of VDAC1 with many proteins involved in Ca²⁺ homeostasis or regulated by Ca²⁺, as well as VDAC-mediated control of cell life and death and the association of VDAC with disease, are also presented.