Sirtuin 3 and mitochondrial permeability transition pore (mPTP): A systematic review

Alzheimer's Disease: A Review of Molecular Mechanisms and Therapeutic Implications by Targeting Sirtuins, Caspases, and GSK-3

Alzheimer's disease (AD) is a neurodegenerative disease with a significant impact on global public health. The primary hallmarks of the disease included amyloid-beta peptide (Aβ) deposition, neurofibrillary tangles (NFT), and synaptic loss. Sirtuins, a group of NAD+-dependent deacetylase enzymes, are key regulators of AD pathogenesis. SIRT1, a member of sirtuins, has been identified to possess neuroprotective properties. Thus, its promising enhancers are included. Further, SIRT2 promising inhibitors are reviewed for therapeutic efficacy. The extrinsic and intrinsic apoptotic pathways of caspases are mediated by CD95 and DNA damage. The promising inhibitors Q-VD-OPh and minocycline are found to be specific for caspase-7 and caspase-3, respectively. Primarily, glycogen synthase kinase-3β (GSK-3β) is found to be involved in the generation of phosphorylated tau. The promising GSK-3 inhibitor included the COB-187 (IC50 = 370 nM) and maleimide-derivative (compound 33, IC50 = 0.09 μM). This review highlights the molecular mechanisms of sirtuin, caspase, and GSK-3 in the pathophysiology of AD. Further, promising modulators specific to these targets are described.

Signaling pathways underlying extracellular trap formation induced by Vibrio alginolyticus in Strongylocentrotus intermedius

Extracellular traps (ETs), comprising a DNA-protein network, are widespread and function as an innate immune defense in many species. Notably, Strongylocentrotus intermedius solely depend on innate immunity for disease resistance. This study investigated the formation and preliminary mechanism of ETs in the coelomocytes of the S. intermedius under the stimulation of bacterium Vibrio alginolyticus. These results revealed that as the concentration of V. alginolyticus increased, the formation of ETs became more significant. Flow cytometry analysis showed that the formation process of ETs was accompanied by changes in mitochondrial indicators, suggesting that mitochondria may be involved in the formation process of V. alginolyticus-induced ETs. Transcriptome analysis indicated that the ETs production by coelomocytes of the S. intermedius was related to glycolysis and ATP synthesis. A total of 2631 differentially expressed genes (DEGs) were screened in this transcriptome. We then screened 34 immune-related DEGs from 16 signaling pathways to construct the PPI network, and defined hub proteins corresponding to genes such as ATP6, ND2, G3PDH, MAPK7 and other related genes. These genes are related to mitochondrial function, glycolytic pathways, and immune pathways. Additionally, the formation of ETs led to alterations in multiple immune regulators, such as TNF, NF-κB, MAPK, PI3K-AKT, and mTOR, implying its role in cellular immunomodulation. Quantitative real-time PCR experiment revealed that the expression changes of some DEGs identified and validated in ET-formation coelomocytes matched transcriptome analysis results. This study provided insights into S. intermedius aquaculture, elucidated marine organism immune mechanisms, and advanced invertebrate innate immunity understanding.

Ca2+ transfer via enhancing ER-Mito coupling contributed to BDE-47- induced hippocampal neuronal necroptosis and cognitive dysfunction

2,2,4,4-Tetrabromodiphenyl ether (BDE-47), a ubiquitous environmental pollutant, has gained increasing attention due to its high level in biological samples and potential neurotoxicity. Recent studies have indicated that the receptor interacting protein kinase 1 (RIPK1)-mediated necroptosis is implicated in BDE-47 cytotoxicity. However, little is known about the underlying mechanism and whether the necroptosis participates in BDE-47-induced neuronal injury and cognitive impairment. Our results indicated that exposure to BDE-47 triggered RIPK1-dependent neuronal necroptosis in mice hippocampi and HT-22 mouse hippocampal neurons. Necrostain-1 (Nec-1), a specific RIPK1 inhibitor, suppressed the RIPK1/RIPK3/mixed lineage kinase-like domain protein (MLKL) signaling and rescued neuronal survival in BDE-47-treated HT-22 neurons. Mechanically, increased mitochondrial Ca2+ influx precipitated the opening of the mitochondrial permeability transition pore (mPTP), leading to occurrence of hippocampal neuronal necroptosis under BDE-47 stress. BDE-47 exposure induced excessive mitochondria-associated endoplasmic reticulum membranes (MAMs) formation and promoted ER-to-mitochondria Ca2+ transfer, while diminishing ER-mitochondrial contacts by Glucose-regulated protein 75 (Grp75)-deficiency remarkably prevented mitochondria Ca2+ overload and opening of mPTP as well as neuronal necroptosis. Notably, Nec-1 pre-treatment could substantially mitigate neuronal/synaptic damage and cognitive impairment in BDE-47-exposed mice. Collectively, these data suggest that BDE-47 exposure intensified endoplasmic reticulum (ER)-mitochondrial (Mito) contact and facilitated Ca2+ transfer from ER towards mitochondria, resulting in mPTP opening-mediated hippocampal neuronal necroptosis and subsequent cognitive dysfunction. Our study shed new light on the mechanisms underlying BDE-47 neurotoxicity and provided a novel therapeutic strategy through targeting RIPK1 kinase activity.

Mitochondria: the hidden engines of traumatic brain injury-driven neurodegeneration

Mitochondria play a critical role in brain energy metabolism, cellular signaling, and homeostasis, making their dysfunction a key driver of secondary injury progression in traumatic brain injury (TBI). This review explores the relationship between mitochondrial bioenergetics, metabolism, oxidative stress, and neuroinflammation in the post-TBI brain. Mitochondrial dysfunction disrupts adenosine triphosphate (ATP) production, exacerbates calcium dysregulation, and generates reactive oxygen species, triggering a cascade of neuronal damage and neurodegenerative processes. Moreover, damaged mitochondria release damage-associated molecular patterns (DAMPs) such as mitochondrial DNA (mtDNA), Cytochrome C, and ATP, triggering inflammatory pathways that amplify tissue injury. We discuss the metabolic shifts that occur post-TBI, including the transition from oxidative phosphorylation to glycolysis and the consequences of metabolic inflexibility. Potential therapeutic interventions targeting mitochondrial dynamics, bioenergetic support, and inflammation modulation are explored, highlighting emerging strategies such as mitochondrial-targeted antioxidants, metabolic substrate supplementation, and pharmacological regulators of mitochondrial permeability transition pores. Understanding these mechanisms is crucial for developing novel therapeutic approaches to mitigate neurodegeneration and enhance recovery following brain trauma.

Neuroinflammation and Natural Antidepressants: Balancing Fire with Flora

Background/Objectives: Major depressive disorder (MDD) is a major global health concern that is intimately linked to neuroinflammation, oxidative stress, mitochondrial dysfunction, and complicated metabolic abnormalities. Traditional antidepressants frequently fall short, highlighting the urgent need for new, safer, and more acceptable therapeutic techniques. Phytochemicals, i.e., natural antidepressants derived from plants, are emerging as powerful plant-based therapies capable of targeting many pathogenic pathways at the same time. Summary: This narrative review synthesizes evidence from preclinical and clinical studies on the efficacy of phytochemicals such as curcumin, polyphenols, flavonoids, and alkaloids in lowering depressed symptoms. Consistent data show that these substances have neuroprotective, anti-inflammatory, and antioxidant properties, altering neuroimmune interactions, reducing oxidative damage, and improving mitochondrial resilience. Particularly, polyphenols and flavonoids have great therapeutic potential because of their capacity to penetrate the blood-brain barrier, inhibit cytokine activity, and encourage neuroplasticity mediated by brain-derived neurotrophic factor (BDNF). Despite promising results, the heterogeneity in study designs, phytochemical formulations, and patient demographics highlights the importance of thorough, standardized clinical studies. Conclusions: This review identifies phytochemicals as compelling adjuvant or independent therapies in depression treatment, providing multimodal mechanisms and enhanced tolerability. Additional research into improved dosage, pharmacokinetics, long-term safety, and integrative therapy approaches is essential. Using phytotherapeutics could considerably improve holistic and customized depression care, encouraging new research routes in integrative neuroscience and clinical psychiatry.

Cytoplasmic DNA and AIM2 inflammasome in RA: where they come from and where they go?

Rheumatoid arthritis is a chronic autoimmune disease of undetermined etiology characterized by symmetric synovitis with predominantly destructive and multiple joint inflammation. Cytoplasmic DNA sensors that recognize protein molecules that are not themselves or abnormal dsDNA fragments play an integral role in the generation and perpetuation of autoimmune diseases by activating different signaling pathways and triggering innate immune signaling pathways and host defenses. Among them, melanoma deficiency factor 2 (AIM2) recognizes damaged DNA and double-stranded DNA and binds to them to further assemble inflammasome, initiating the innate immune response and participating in the pathophysiological process of rheumatoid arthritis. In this article, we review the research progress on the source of cytoplasmic DNA, the mechanism of assembly and activation of AIM2 inflammasome, and the related roles of other cytoplasmic DNA sensors in rheumatoid arthritis.

Permeabilization of the outer mitochondrial membrane: Mechanisms and consequences

Permeabilization of the outer mitochondrial membrane is а physiological process that can allow certain molecules to pass through it, such as low molecular weight solutes required for cellular respiration. This process is also important for the development of various modes of cell death. Depending on the severity of this process, cells can die by autophagy, apoptosis, or necrosis/necroptosis. Distinct types of pores can be opened at the outer mitochondrial membrane depending on physiological or pathological stimuli, and different mechanisms can be activated in order to open these pores. In this comprehensive review, all these types of permeabilization, the mechanisms of their activation, and their role in various diseases are discussed.

Crosstalk among mitophagy, pyroptosis, ferroptosis, and necroptosis in central nervous system injuries

Central nervous system injuries have a high rate of resulting in disability and mortality; however, at present, effective treatments are lacking. Programmed cell death, which is a genetically determined form of active and ordered cell death with many types, has recently attracted increasing attention due to its functions in determining the fate of cell survival. A growing number of studies have suggested that programmed cell death is involved in central nervous system injuries and plays an important role in the progression of brain damage. In this review, we provide an overview of the role of programmed cell death in central nervous system injuries, including the pathways involved in mitophagy, pyroptosis, ferroptosis, and necroptosis, and the underlying mechanisms by which mitophagy regulates pyroptosis, ferroptosis, and necroptosis. We also discuss the new direction of therapeutic strategies targeting mitophagy for the treatment of central nervous system injuries, with the aim to determine the connection between programmed cell death and central nervous system injuries and to identify new therapies to modulate programmed cell death following central nervous system injury. In conclusion, based on these properties and effects, interventions targeting programmed cell death could be developed as potential therapeutic agents for central nervous system injury patients.

Mitochondrial sirtuin 3 and role of natural compounds: the effect of post-translational modifications on cellular metabolism

Sirtuins (SIRTs) are a family of proteins with enzymatic activity. In particular, they are a family of class III NAD+-dependent histone deacetylases and ADP-ribosyltransferases. NAD+-dependent deac(et)ylase activities catalyzed by sirtuin include ac(et)ylation, propionylation, butyrylation, crotonylation, manylation, and succinylation. Specifically, human SIRT3 is a 399 amino acid protein with two functional domains: a large Rossmann folding motif and NAD+ binding, and a small complex helix and zinc-binding motif. SIRT3 is widely expressed in mitochondria-rich tissues and is involved in maintaining mitochondrial integrity, homeostasis, and function. Moreover, SIRT3 regulates related diseases, such as aging, hepatic, kidney, neurodegenerative and cardiovascular disease, metabolic diseases, and cancer development. In particular, one of the most significant and damaging post-translational modifications is irreversible protein oxidation, i.e. carbonylation. This process is induced explicitly by increased ROS production due to mitochondrial dysfunction. SIRT3 is carbonylated by 4-hydroxynonenal at the level of Cys280. The carbonylation induces conformational changes in the active site, resulting in allosteric inhibition of SIRT3 activity and loss of the ability to deacetylate and regulate antioxidant enzyme activity. Phytochemicals and, in particular, polyphenols, thanks to their strong antioxidant activity, are natural compounds with a positive regulatory action on SIRT3 in various pathologies. Indeed, the enzymatic SIRT3 activity is modulated, for example, by different natural polyphenol classes, including resveratrol and the bergamot polyphenolic fraction. Thus, this review aims to elucidate the mechanisms by which phytochemicals can interact with SIRT3, resulting in post-translational modifications that regulate cellular metabolism.

Ramelteon alleviates myocardial ischemia/reperfusion injury (MIRI) through Sirt3--dependent regulation of cardiomyocyte apoptosis

Reperfusion stands as a pivotal intervention for ischemic heart disease. However, the restoration of blood flow to ischemic tissue always lead to further damage, which is known as myocardial ischemia/reperfusion injury (MIRI). Ramelteon is an orally administered drug used to improve sleep quality, which is famous for its high bioadaptability and absence of notable addictive characteristics. However, the specific mechanism by which it improves MIRI is still unclear. Sirtuin-3 (Sirt3), primarily located in mitochondria, is crucial in mitigating many cardiac diseases, including MIRI. Based on the structure of Sirt3, we simulated molecular docking and identified several potential amino acid binding sites between it and ramelteon. Therefore, we propose a hypothesis that ramelteon may exert cardioprotective effects by activating the Sirt3 signaling pathway. Our results showed that the activation levels and expression level of Sirt3 were significantly decreased in MIRI tissue and H2O2 stimulated H9C2 cells, while ramelteon treatment upregulated Sirt3 activity and expression. After treat with 3-TYP, a classic Sirt3 activity inhibitor, we constructed myocardial ischemia/reperfusion surgery in vivo and induced H9C2 cells with H2O2 in vitro. The results showed that the myocardial protection and anti-apoptotic effects of ramelteon were antagonized by 3-TYP, indicating that the activation of Sirt3 is a key mechanism for ramelteon to exert myocardial protection. In summary, our results confirm a novel mechanism by which ramelteon improves MIRI by activating Sirt3 signaling pathway, providing strong evidence for the treatment of MIRI with ramelteon.

Lycopene Maintains Mitochondrial Homeostasis to Counteract the Enterotoxicity of Deoxynivalenol

The intestinal tract is a target organ for Deoxynivalenol (DON) absorption and toxicity. Mitochondrial homeostasis imbalance is the gut toxicity mechanism of DON. Lycopene (LYC) has intestinal protective effects and can maintain mitochondrial homeostasis in response to various danger signals. The purpose of this study was to explore the protective effect of LYC on DON-induced IPEC-J2 cells damage. These results showed that DON exposure induced an increase in the levels of malondialdehyde and reactive oxygen species (ROS) in IPEC-J2 cells. DON impaired IPEC-J2 cell barrier function and caused mitochondrial dysfunction by inducing mitochondrial permeability transition pore (MPTP) opening, mitochondrial membrane potential (MMP) reducing, destroying mitochondrial fission factors, mitochondrial fusion factors, and mitophagy factors expression. However, adding LYC can reduce the toxic effects of DON-induced IPEC-J2 cells and decrease cellular oxidative stress, functional damage, mitochondrial dynamics imbalance, and mitophagy processes. In conclusion, LYC maintains mitochondrial homeostasis to counteract the IPEC-J2 cells' toxicity of DON.

Premature senescence and cardiovascular disease following cancer treatments: mechanistic insights

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality, especially among the aging population. The "response-to-injury" model proposed by Dr. Russell Ross in 1999 emphasizes inflammation as a critical factor in atherosclerosis development, with atherosclerotic plaques forming due to endothelial cell (EC) injury, followed by myeloid cell adhesion and invasion into the blood vessel walls. Recent evidence indicates that cancer and its treatments can lead to long-term complications, including CVD. Cellular senescence, a hallmark of aging, is implicated in CVD pathogenesis, particularly in cancer survivors. However, the precise mechanisms linking premature senescence to CVD in cancer survivors remain poorly understood. This article aims to provide mechanistic insights into this association and propose future directions to better comprehend this complex interplay.

Ginsenosides for therapeutically targeting inflammation through modulation of oxidative stress

Ginsenosides are steroid glycosides derived from ginseng plants such as Panax ginseng, Panax quinquefolium, and Panax notoginseng. Advances in recent studies have identified numerous physiological functions of each type of ginsenoside, i.e., immunomodulatory, antioxidative, and anti-inflammatory functions, in the context of inflammatory diseases. Accumulating evidence has revealed the molecular mechanisms by which the single or combined ginsenoside(s) exhibit anti-inflammatory effects, although it remains largely unclear. It is well known that excessive production of reactive oxygen species (ROS) is associated with pathological inflammation and cell death in a variety of cells, and that inhibition of ROS generation ameliorates the local and systemic inflammatory responses. The mechanisms by which ginsenosides attenuate inflammation are largely unknown; however, targeting ROS is suggested as one of the crucial mechanisms for the ginsenosides to control the pathological inflammation in the immune and non-immune cells. This review will summarize the latest progress in ginsenoside studies, particularly in the context of antioxidant mechanisms for its anti-inflammatory effects. A better understanding of the distinct types and the combined action of ginsenosides will pave the way for developing potential preventive and therapeutic modalities in treating various inflammation-related diseases.

Mitochondrial Dysfunction in Cardiac Diseases and Therapeutic Strategies

Mitochondria are the main site of intracellular synthesis of ATP, which provides energy for various physiological activities of the cell. Cardiomyocytes have a high density of mitochondria and mitochondrial damage is present in a variety of cardiovascular diseases. In this paper, we describe mitochondrial damage in mitochondrial cardiomyopathy, congenital heart disease, coronary heart disease, myocardial ischemia-reperfusion injury, heart failure, and drug-induced cardiotoxicity, in the context of the key roles of mitochondria in cardiac development and homeostasis. Finally, we discuss the main current therapeutic strategies aimed at alleviating mitochondrial impairment-related cardiac dysfunction, including pharmacological strategies, gene therapy, mitochondrial replacement therapy, and mitochondrial transplantation. It is hoped that this will provide new ideas for the treatment of cardiovascular diseases.

Role of SIRT3 in mitochondrial biology and its therapeutic implications in neurodegenerative disorders

Sirtuin 3 (SIRT3), a mitochondrial deacetylase expressed preferentially in high-metabolic-demand tissues including the brain, requires NAD⁺ as a cofactor for catalytic activity. It regulates various processes such as energy homeostasis, redox balance, mitochondrial quality control, mitochondrial unfolded protein response (UPRmt), biogenesis, dynamics and mitophagy by altering protein acetylation status. Reduced SIRT3 expression or activity causes hyperacetylation of hundreds of mitochondrial proteins, which has been linked with neurological abnormalities, neuro-excitotoxicity and neuronal cell death. A body of evidence has suggested, SIRT3 activation as a potential therapeutic modality for age-related brain abnormalities and neurodegenerative disorders.

Synergistic Beneficial Effects of Resveratrol and Diet on High-Fat Diet-Induced Obesity

Introduction: Despite decades of research, obesity and its related medical complications remain a major health concern globally. Therefore, novel therapeutic strategies are needed to combat obesity and its numerous debilitating complications. Resveratrol (RES) has a potential therapeutic effect in obesity and diabetes by improving oxidative metabolism and insulin signaling. Background and Objectives: The aim of this study was to investigate the effect of RES treatment on weight loss and glucose and fatty acid metabolism. Methods: Obesity was induced in 24 mice by exposure to a high-fat diet (HFD) for 8 weeks. Mice were randomly assigned to one group of either: group 1: control, non-treated low-fat diet (LFD) for 12 weeks (n = 8), group 2: non-treated high-fat diet (HFD) for 12 weeks (n = 8), group 3: RES-treated HFD (HFD + RES) (n = 8), or group 4: RES-treated and switched to LFD (HFD-LFD + RES) (n = 8). HFD + RES mice were first fed an HFD for 8 weeks followed by 4 weeks of RES. The HFD-LFD + RES group was first fed an HFD for 8 weeks and then treated with RES and switched to an LFD for 4 weeks. Results: After 12 weeks, group 2 mice had significantly higher body weights compared to group 1 (23.71 ± 1.95 vs. 47.83 ± 2.27; p < 0.05). Group 4 had a significant decrease in body weight and improvement in glucose tolerance compared to mice in group 2 (71.3 ± 1.17 vs. 46.1 ± 1.82 and 40.9 ± 1.75, respectively; p < 0.05). Skeletal muscles expression of SIRT1, SIRT3, and PGC1α were induced in group 3 and 4 mice compared to group 2 (p < 0.01), with no changes in AMP-activated protein kinase expression levels. Furthermore, combination of RES and diet ameliorated skeletal muscle intermediate lipid accumulation and significantly improved insulin sensitivity and secretion. Conclusions: The results of this study suggest a synergistic beneficial effect of LFD and RES to lower body weight and enhance glucose and fatty acid metabolism.

Metabolic and Cellular Compartments of Acetyl-CoA in the Healthy and Diseased Brain

The human brain is characterised by the most diverse morphological, metabolic and functional structure among all body tissues. This is due to the existence of diverse neurons secreting various neurotransmitters and mutually modulating their own activity through thousands of pre- and postsynaptic interconnections in each neuron. Astroglial, microglial and oligodendroglial cells and neurons reciprocally regulate the metabolism of key energy substrates, thereby exerting several neuroprotective, neurotoxic and regulatory effects on neuronal viability and neurotransmitter functions. Maintenance of the pool of mitochondrial acetyl-CoA derived from glycolytic glucose metabolism is a key factor for neuronal survival. Thus, acetyl-CoA is regarded as a direct energy precursor through the TCA cycle and respiratory chain, thereby affecting brain cell viability. It is also used for hundreds of acetylation reactions, including N-acetyl aspartate synthesis in neuronal mitochondria, acetylcholine synthesis in cholinergic neurons, as well as divergent acetylations of several proteins, peptides, histones and low-molecular-weight species in all cellular compartments. Therefore, acetyl-CoA should be considered as the central point of metabolism maintaining equilibrium between anabolic and catabolic pathways in the brain. This review presents data supporting this thesis.

Aspirin blocks AMPK/SIRT3-mediated glycolysis to inhibit NSCLC cell proliferation

Non-small cell lung cancer (NSCLC) has the highest incidence and mortality in the world. Aspirin has been reported to promote apoptosis, inhibit proliferation, stemness, angiogenesis, cancer-associated inflammation and migration in NSCLC. But the effect of aspirin on aerobic glycolysis in NSCLC is less reported. In the present study, we investigated whether aspirin blocked aerobic glycolysis of NSCLC cells to inhibit proliferation. Our results showed that aspirin inhibited viability, PCNA expression, ability of colony formation, dimished extracellular acidification rate (ECAR), oxygen consumption rate (OCR) and production of pyruvic acid and lactic acid, accompanied with reduced mitochondrial membrane potential (MMP), PGC-1α expression and ROS production, indicating mitochondrial dysfunction in NSCLC cells. AMPK and mitochondrial-localized deacetylase sirtuin 3 (SIRT3) were identified as the relevant molecular targets in glycolysis, but mechanism and relationship between AMPK and SIRT3 for aspirin induced glycolysis inhibition remain unknown in cancer cells. The investigation of underlying mechanism indicated that aspirin activated AMPK pathway to inhibit aerobic glycolysis and proliferation by upregulating SIRT3 after application of compound C (CC), an inhibitor of AMPK activity or SIRT3 siRNA. Upon activation of SIRT3, aspirin promoted the release of hexokinase-II (HK-II) from mitochondrial outer membrane to cytosol by deacetylating cyclophilin D (CypD). Consistently, aspirin significantly inhibited the growth of NSCLC xenografts and exhibited antitumor activity probably through AMPK/SIRT3/HK-II pathway in vivo. Collectively, AMPK/SIRT3/HK-II pathway plays a critical role in anticancer effects of aspirin, and our findings might serve as potential target for clinical practice and chemoprevention of aspirin in NSCLC.