Mitophagy and Alzheimer's Disease: Cellular and Molecular Mechanisms

Decoding molecular mechanisms: brain aging and Alzheimer's disease

The complex morphological, anatomical, physiological, and chemical mechanisms within the aging brain have been the hot topic of research for centuries. The aging process alters the brain structure that affects functions and cognitions, but the worsening of such processes contributes to the pathogenesis of neurodegenerative disorders, such as Alzheimer's disease. Beyond these observable, mild morphological shifts, significant functional modifications in neurotransmission and neuronal activity critically influence the aging brain. Understanding these changes is important for maintaining cognitive health, especially given the increasing prevalence of age-related conditions that affect cognition. This review aims to explore the age-induced changes in brain plasticity and molecular processes, differentiating normal aging from the pathogenesis of Alzheimer's disease, thereby providing insights into predicting the risk of dementia, particularly Alzheimer's disease.

Beneficial effects of mitophagy enhancers on amyloid beta-induced mitochondrial and synaptic toxicities in Alzheimer's disease

The purpose of our study is to investigate the beneficial effects of mitophagy enhancers against mutant amyloid precursor protein (APP) and amyloid beta (Aβ) induced mitochondrial and synaptic toxicities in Alzheimer's disease (AD). Research spanning over two decades highlights the critical role of mitochondrial dysfunction and synaptic damage in the pathogenesis of both early-onset and late-onset AD. Emerging evidence suggests impaired clearance of damaged mitochondria is an early pathological event in AD, positioning mitophagy enhancers as potential therapeutic candidates. This study determined the optimal doses of four mitophagy enhancers-Urolithin A (UA), actinonin, tomatidine, and nicotinamide riboside (NR)-using immortalized mouse hippocampal (HT22) neurons. HT22 cells were transfected with mutant APP (mAPP) cDNA and treated with the enhancers. The effects were assessed by evaluating mRNA and protein expression levels of genes involved in mitochondrial dynamics, biogenesis, mitophagy, and synaptic function, alongside cell survival and mitochondrial respiration. Mitochondrial morphology was also examined in treated and untreated mAPP-HT22 cells. Results showed that mAPP-HT22 cells exhibited increased mitochondrial fission, reduced fusion, downregulated synaptic and mitophagy-related genes, diminished cell survival, impaired mitochondrial respiration, and excessively fragmented, shortened mitochondria. Treatment with mitophagy enhancers reversed these deficits, restoring mitochondrial and synaptic health. Enhanced cell survival, upregulation of mitochondrial fusion, synaptic, and mitophagy genes, improved mitochondrial structure, and reduced fragmentation were observed. Notably, UA demonstrated the most robust mitigating effects. These findings underscore the therapeutic potential of mitophagy enhancers, particularly UA, as promising candidates to treat mitochondrial and synaptic dysfunctions in AD.

Mitochondrial medicine: "from bench to bedside" 3PM-guided concept

Mitochondria are the primary sites for aerobic respiration and play a vital role in maintaining physiologic function at the cellular and organismal levels. Physiologic mitochondrial homeostasis, functions, health, and any kind of mitochondrial impairments are associated with systemic effects that are linked to the human health and pathologies. Contextually, mitochondria are acting as a natural vital biosensor in humans controlling status of physical and mental health in a holistic manner. So far, no any disorder is known as happening to humans independently from a compromised mitochondrial health as the cause (primary mitochondrial dysfunction) or a target of collateral damage (secondary mitochondrial injury). This certainty makes mitochondrial medicine be the superior instrument to reach highly ambitious objectives of predictive, preventive, and personalized medicine (PPPM/3PM). 3PM effectively implements the paradigm change from the economically ineffective reactive medical services to a predictive approach, targeted prevention and treatments tailored to individualized patient profiles in primary (protection against health-to-disease transition) and secondary (protection against disease progression) healthcare. Mitochondrial DNA (mtDNA) properties differ significantly from those of nuclear DNA (nDNA). For example, mtDNA as the cell-free DNA molecule is much more stable compared to nDNA, which makes mtDNA be an attractive diagnostic target circulating in human body fluids such as blood and tear fluid. Further, genetic variations in mtDNA contribute to substantial individual differences in disease susceptibility and treatment response. To this end, the current gene editing technologies, such as clustered regularly interspaced short palindromic repeats (CRISPR)/Cas, are still immature in mtDNA modification, and cannot be effectively applied in clinical practice posing a challenge for mtDNA-based therapies. In contrast, comprehensive multiomics technologies offer new insights into mitochondrial homeostasis, health, and functions, which enables to develop more effective multi-level diagnostics and targeted treatment strategies. This review article highlights health- and disease-relevant mitochondrial particularities and assesses involvement of mitochondrial medicine into implementing the 3PM objectives. By discussing the interrelationship between 3PM and mitochondrial medicine, we aim to provide a foundation for advancing early and predictive diagnostics, cost-effective targeted prevention in primary and secondary care, and exemplify personalized treatments creating proof-of-concept approaches for 3PM-guided clinical applications.

Impact of diet and exercise on mitochondrial quality and mitophagy in Alzheimer's disease

Alzheimer's disease (AD) is a devastating neurodegenerative disorder that affects millions of people worldwide. It is characterized by the accumulation of beta-amyloid and phosphorylated tau, synaptic damage, and mitochondrial abnormalities in the brain, leading to the progressive loss of cognitive function and memory. In AD, emerging research suggests that lifestyle factors such as a healthy diet and regular exercise may play a significant role in delaying the onset and progression of the disease. Mitochondria are often referred to as the powerhouse of the cell, as they are responsible for producing the energy to cells, including neurons to maintain cognitive function. Our article elaborates on how mitochondrial quality and function decline with age and AD, leading to an increase in oxidative stress and a decrease in ATP production. Decline in mitochondrial quality can impair cellular functions contributing to the development and progression of disease with the loss of neuronal functions in AD. This article also covered mitophagy, the process by which damaged or dysfunctional mitochondria are selectively removed from the cell to maintain cellular homeostasis. Impaired mitophagy has been implicated in the progression and pathogenesis of AD. We also discussed the impact of impaired mitophagy implicated in AD, as the accumulation of damaged mitochondria can lead to increased oxidative stress. We expounded how dietary interventions and exercise can help to improve mitochondrial quality, and mitochondrial function and enhance mitophagy in AD. A diet rich in antioxidants, polyphenols, and mitochondria-targeted small molecules has been shown to enhance mitochondrial function and protect against oxidative stress, particularly in neurons with aged and mild cognitively impaired subjects and AD patients. Promoting a healthy lifestyle, mainly balanced diet and regular exercise that support mitochondrial health, in an individual can potentially delay the onset and progression of AD. In conclusion, a healthy diet and regular exercise play a crucial role in maintaining mitochondrial quality and mitochondrial function, in turn, enhancing mitophagy and synaptic activities that delay AD in the elderly populations.

Role of Mitochondrial Dysfunctions in Neurodegenerative Disorders: Advances in Mitochondrial Biology

Mitochondria, essential organelles responsible for cellular energy production, emerge as a key factor in the pathogenesis of neurodegenerative disorders. This review explores advancements in mitochondrial biology studies that highlight the pivotal connection between mitochondrial dysfunctions and neurological conditions such as Alzheimer's, Parkinson's, Huntington's, ischemic stroke, and vascular dementia. Mitochondrial DNA mutations, impaired dynamics, and disruptions in the ETC contribute to compromised energy production and heightened oxidative stress. These factors, in turn, lead to neuronal damage and cell death. Recent research has unveiled potential therapeutic strategies targeting mitochondrial dysfunction, including mitochondria targeted therapies and antioxidants. Furthermore, the identification of reliable biomarkers for assessing mitochondrial dysfunction opens new avenues for early diagnosis and monitoring of disease progression. By delving into these advancements, this review underscores the significance of understanding mitochondrial biology in unraveling the mechanisms underlying neurodegenerative disorders. It lays the groundwork for developing targeted treatments to combat these devastating neurological conditions.

Senegenin regulates the mechanism of insomnia through the Keap1/Nrf2/PINK1/Parkin pathway mediated by GAD67

GAD67 impacts insomnia as a key enzyme catalysing the conversion of glutamate (Glu) to gamma-aminobutyric acid (GABA). Senegenin enhances neuroprotection and is used widely to treat insomnia and other neurological diseases. This study aimed to investigate how senegenin regulates insomnia through a GAD67-mediated signalling pathway. We measured GAD67 expression levels in insomnia patients and evaluated the expression levels of GAD67 and Keap1/Nrf2/Parkin/PINK1-related cytokines following GAD67 lentiviral transfection in PC12 cells and in rat models. We also assessed cellular reactive oxygen species (ROS) and mitochondrial membrane potential levels. Additionally, EEG/EMG was used to analyse the sleep phases of rats and to assess memory and exploration functions. Pathological changes and the expression of GAD67 and sleep-related proteins in the hippocampus were examined. The results showed that GAD67 expression was increased in insomnia patients, ROS levels were elevated, and the mitochondrial membrane potential was decreased in the GAD67-KD group. Insomnia rats exhibited changes in sleep rhythm, learning, and exploration dysfunction, pathological changes in the CA1 region of the hippocampus, and differential expression of GAD67 and sleep-related factors. Inhibitory neurofactor expression levels were decreased in insomnia rats, showing a positive correlation in the GAD67-KD group and a negative correlation in the GAD67-OE group. Conversely, excitatory factor expression levels were increased in insomnia rats, showing a positive correlation in the GAD67-KD group and a negative correlation in the GAD67-OE group. Senegenin intervention modulated cytokine expression levels. In conclusion, GAD67 negatively regulates insomnia, and senegenin can regulate insomnia by mediating the expression of cytokines in the GAD67-regulated Keap1/Nrf2/Parkin/PINK1 pathway.

OSBP Participates in Neural Damage Repair by Regulating Lysosome Transport Under Oxidative Stress

Oxidative stress is a major pathological factor in acute brain injury, such as traumatic brain injury (TBI). As highly branched cells, the transport of lysosomes plays a crucial role in neuronal homeostasis. However, the effects and mechanisms of oxidative damage on axonal lysosome transport remain unknown. In this study, we demonstrated that the downregulation of the membrane lipid orchestrator oxysterol-binding protein (OSBP) induced by oxidative stress alters the subcellular distribution of lysosomes in neurons through regulating lysosomal phosphatidylinositol-4-monophosphate (PI(4)P)/phosphatidylinositol-3-monophosphate (PI(3)P) contents, thus disrupting lysosomal transport. The results of the cell experiments confirmed the occurrence of an autophagic pressure burst, disordered anterograde lysosome transport, and an imbalance in the PI(4)P/PI(3)P ratio in neurons after H2O2 treatment. Mechanistically, oxidative damage reduced neuronal OSBP protein levels, thus contributing to lysosomal PI(4)P storage. Furthermore, a protein‒liposome binding assay revealed that compared with liposomes containing PI(4)P, liposomes containing PI(3)P or cholesterol presented decreased coprecipitation of Arl8. The overexpression of OSBP restored the PI(4)P/PI(3)P content, improved the binding ability of Arl8 to bind to lysosomes, increased lysosome localization in neurites, and promoted axonal injury repair. Finally, overexpression of neuronal OSBP through adeno-associated virus intervention in vivo alleviated dendritic damage and improved the neurological function of mice with TBI. Taken together, these findings suggest that disturbance of OSBP induced by oxidative stress results in abnormal lysosomal distribution and contributes to neuronal malfunction in TBI, and OSBP could be a potential target to promote neuronal repair and regeneration by regulating lysosomal lipid composition and axonal localization.

Mitophagy in Alzheimer's disease and other metabolic disorders: A focus on mitochondrial-targeted therapeutics

Mitochondria, as central regulators of cellular processes such as energy production, apoptosis, and metabolic homeostasis, are essential to cellular function and health. The maintenance of mitochondrial integrity, especially through mitophagy-the selective removal of impaired mitochondria-is crucial for cellular homeostasis. Dysregulation of mitochondrial function, dynamics, and biogenesis is linked to neurodegenerative and metabolic diseases, notably Alzheimer's disease (AD), which is increasingly recognized as a metabolic disorder due to its shared pathophysiologic features: insulin resistance, oxidative stress, and chronic inflammation. In this review, we highlight recent advancements in pharmacological interventions, focusing on agents that modulate mitophagy, mitochondrial uncouplers that reduce oxidative phosphorylation, compounds that directly scavenge reactive oxygen species to alleviate oxidative stress, and molecules that ameliorate amyloid beta plaque accumulation and phosphorylated tau pathology. Additionally, we explore dietary and lifestyle interventions-MIND and ketogenic diets, caloric restriction, physical activity, hormone modulation, and stress management-that complement pharmacological approaches and support mitochondrial health. Our review underscores mitochondria's central role in the pathogenesis and potential treatment of neurodegenerative and metabolic diseases, particularly AD. By advocating for an integrated therapeutic model that combines pharmacological and lifestyle interventions, we propose a comprehensive approach aimed at mitigating mitochondrial dysfunction and improving clinical outcomes in these complex, interrelated diseases.

Targeting LKB1-AMPK-SIRT1-induced autophagy and mitophagy pathways improves cerebrovascular homeostasis in APP/PS1 mice

BACKGROUND

Alzheimer's disease (AD) is the most common and severe degenerative disorder of the central nervous system in the elderly, profoundly impacting patients' quality of life. However, effective therapeutic agents for AD are still lacking. Bazi Bushen capsule (BZBS) is a traditional Chinese herbal compound with potential neuroprotective effects, yet its underlying mechanisms remain poorly understood.

METHODS

In this study, we utilized APP/PS1 transgenic mice to assess the therapeutic efficacy of BZBS. Initially, we evaluated the spatial learning and memory of the mice using the Barnes maze. The brain microcirculation was assessed through a small-animal ultrasound system, two-photon in vivo imaging, and micro-computed tomography angiography. Molecular, biochemical, and pathological analyses were conducted on brain tissues. Through network pharmacology, we identified potential intervention pathways and targets for BZBS in the treatment of AD, which we subsequently validated both in vivo and in vitro. Additionally, we employed molecular virtual docking screening and biolayer interferometry to elucidate the direct interactions of ginsenoside Rg5 and ginsenoside Ro in BZBS with AMPK and LKB1 proteins.

RESULTS

The BZBS intervention significantly enhanced spatial learning and memory in APP/PS1 mice while decreasing Aβ deposition. Furthermore, BZBS protected cerebrovascular homeostasis and mitigated neuroinflammation, as evidenced by decreased blood-brain barrier permeability, increased expression of tight-junction proteins, and restored cerebral blood flow. Mechanistically, ginsenosides Rg5 and Ro in BZBS directly bind to AMPK and LKB1 proteins, activating the LKB1-AMPK-SIRT1 signaling pathway, promoting autophagy and mitochondrial autophagy, and alleviating oxidative stress damage in endothelial cells.

CONCLUSIONS

BZBS enhances autophagy-related activity, decreases Aβ deposition, and improves endothelial cell homeostasis through the activation of the LKB1-AMPK-SIRT1 signaling pathway, ultimately leading to improved cognitive function in mice with AD. This study highlights the importance of enhancing autophagic activity and maintaining cerebrovascular homeostasis in mitigating cognitive decline in AD, providing evidence and new insights into the application of compound medicines for treating age-related neurological disorders.

Mitochondrial Alterations in Alzheimer's Disease: Insight from the 5xFAD Mouse Model

Mitochondrial dysfunction is increasingly recognized as a key factor in Alzheimer's disease (AD) pathogenesis, but the precise relationship between mitochondrial dynamics and proteinopathies in AD remains unclear. This study investigates the role of mitochondrial dynamics and function in the hippocampal tissue and peripheral blood mononuclear cells (PBMCs) of 5xFAD transgenic mice, as a model of AD. The levels of mitochondrial fusion proteins OPA1 and MFN2 and fission proteins DRP1 and phospho-DRP1 (S616) at 3, 6, and 9 months of age were assessed. Western blot analysis revealed significantly lower levels of OPA1 and MFN2 in the hippocampus of 6- and 9-month-old transgenic (TG) 5xFAD mice compared to controls (CTR), while DRP1 and pDRP1 levels were increased in 9-month-old TG mice. Additionally, MFN2 were decreased in the PBMCs of 9-month-old TG mice, indicating systemic mitochondrial alterations. Ultrastructural analysis of hippocampal tissues showed substantial alterations in mitochondrial morphology, including abnormalities in size and shape, a preponderance of teardrop-shaped mitochondria, and alterations in the somatic mitochondria-ER complex. Notably, mitochondria-associated ER contact sites were more distant in TG mice, suggesting functional impairments. Flow cytometric measurements demonstrated decreased mitochondrial membrane potential and mass, along with increased superoxide production, in the PBMCs of TG mice, particularly at 9 months, highlighting compromised mitochondrial function. Levels of key mitochondrial proteins including VDAC, TOM2O, and mitophagy-related protein PINK1 levels altered in both central and peripheral tissue of TG mice. These findings suggest that mitochondrial dysfunction and altered dynamics are early events in AD development in 5xFAD mice, manifesting in both central and peripheral tissues, and support the notion that mitochondrial abnormalities are an integral component of AD pathology. These insights might lead to the development of targeted therapies that modulate mitochondrial dynamics and function to mitigate AD progression.

The role of mitochondrial dysfunction in the pathogenesis of Alzheimer's disease and future strategies for targeted therapy

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by progressive cognitive decline, behavioral impairments, and psychiatric comorbidities. The pathogenesis of AD remains incompletely elucidated, despite advances in dominant hypotheses such as the β-amyloid (Aβ) cascade, tauopathy, cholinergic deficiency, and neuroinflammation mechanisms. However, these hypotheses inadequately explain the multifactorial nature of AD, which exposes limitations in our understanding of its mechanisms. Mitochondrial dysfunction is known to play a pivotal role in AD, and since patients exhibit intracellular mitochondrial dysfunction and structural changes in the brain at an early stage, correcting the imbalance of mitochondrial homeostasis and the cytopathological changes caused by it may be a potential target for early treatment of AD. Mitochondrial structural abnormalities accelerate AD pathogenesis. For instance, structural and functional alterations in the mitochondria-associated endoplasmic reticulum membrane (MAM) can disrupt intracellular Ca2⁺ homeostasis and cholesterol metabolism, consequently promoting Aβ accumulation. In addition, the overaccumulation of Aβ and hyperphosphorylated tau proteins can further damage neurons by disrupting mitochondrial integrity and mitophagy, thereby amplifying pathological aggregation and exacerbating neurodegeneration in AD. Furthermore, Aβ deposition and abnormal tau proteins can disrupt mitochondrial dynamics through dysregulation of fission/fusion proteins, leading to excessive mitochondrial fragmentation and subsequent dysfunction. Additionally, hyperphosphorylated tau proteins can impair mitochondrial transport, resulting in axonal dysfunction in AD. This article reviews the biological significance of mitochondrial structural morphology, dynamics, and mitochondrial DNA (mtDNA) instability in AD pathology, emphasizing mitophagy abnormalities as a critical contributor to AD progression. Additionally, mitochondrial biogenesis and proteostasis are critical for maintaining mitochondrial function and integrity. Impairments in these processes have been implicated in the progression of AD, further highlighting the multifaceted role of mitochondrial dysfunction in neurodegeneration. It further discusses the therapeutic potential of mitochondria-targeted strategies for AD drug development.

Mitochondrial Genome-Encoded lncND5 Regulates Mitophagy in Hypoxic Pulmonary Artery Smooth Muscle Cell

Long noncoding RNAs (lncRNAs) are implicated in pulmonary hypertension (PH) progression. However, the underlying mechanisms remain largely unknown. Although mitophagy plays a crucial role in hypoxia-induced PH pathogenesis, the role of lncRNAs in mitophagy remains unclear. Especially, the mechanism of lncRNA encoded by the mitochondrial genome in regulating mitophagy needs to be elucidated. We explored the role of lncND5 in human pulmonary artery smooth muscle cells (PASMCs) and Sugen5416 plus hypoxia (SuHx)-induced PH mouse model in vitro and in vivo. LncND5 expression and localization were detected using real-time quantitative polymerase chain reaction (RT-qPCR) and fluorescence in situ hybridization (FISH). We investigated the molecular mechanism of lncND5 using western blotting, flow cytometry, RNA immunoprecipitation, RNA pulldown, transmission electron microscopy (TEM), immunofluorescence (IF), and echocardiography. Mitochondrial lncND5 expression was decreased under hypoxia in human PASMCs. Mechanistically, in the mitochondria, lncND5 maintains complex I activity by binding with mitochondrial ADH-ubiquinone oxidoreductase chain 5 (MT-ND5) at nucleotides 1086-1159 bp, thereby regulating mitochondrial reactive oxygen species (mROS) release and alleviating mitophagy. Additionally, lncND5 regulates mitophagy via cardiolipin (CL), which regulates complex I activity, inhibiting ROS release then relieving mitophagy. In the cytoplasm, lncND5 inhibits mitophagy by directly interacting with hydroxymethylglutaryl-CoA synthase 1 (HMGCS1). Notably, lncND5 is transported from the mitochondria to the cytoplasm and is mediated by TAR DNA-binding protein 43 (TDP-43). Our findings, for the first time, reveal that lncND5 may be a potential therapeutic approach for PH.

Mitotherapy in Alzheimer's and Parkinson's diseases: A systematic review of preclinical studies

BACKGROUND

Alzheimer's disease (AD) and Parkinson's disease (PD) are prevalent neurodegenerative disorders and strongly affect both the patients' lives and their caregivers. Strategy to improve and restore mitochondrial function, as well as to treat mitochondria-associated diseases, as observed in the pathophysiology of AD and PD. The current study aimed to investigate the potential of mitotherapy in AD and PD in preclinical studies.

METHODS

We conducted a systematic search of articles in English related to mitotherapy in AD and PD animal models published until October 2024 in the selected bibliographic databases, including PubMed, Scopus, EMBASE, and Google Scholar, and the reference lists of relevant review articles published. The quality of the final selected studies was assessed using the Collaborative Approach to Meta-Analysis and Review of Animal Studies (CAMARADES) checklists and the SYRCLE risk of bias tool. The initial search resulted in 231 studies, and after screening the titles and abstracts, 30 studies were recognized. Finally, 7 studies met the inclusion criteria.

RESULTS

Despite restricted knowledge of the mitotherapy mechanisms, evidence shows that exogenous mitochondria exert neuroprotective effects via improving mitochondrial function, reducing oxidative stress and inflammation in preclinical models of AD and PD.

CONCLUSION

This systematic review summarizes the preclinical studies on mitotherapy and provides evidence favoring mitochondria transplantation's protective effects in animal PD and AD models.

Review of FUNDC1-mediated mitochondrial autophagy in Alzheimer's disease

Mitochondrial autophagy is a critical quality control mechanism that eliminates dysfunctional mitochondria to maintain cellular homeostasis. Among receptor-dependent mitophagy pathways, FUN14 domain-containing 1 (FUNDC1)-a mitochondrial outer membrane protein harboring an LC3-interacting region (LIR)-plays a central role by directly binding to LC3 under stress conditions, thereby initiating autophagosome encapsulation of damaged organelles. Emerging evidence implicates FUNDC1 dysregulation in neurodegenerative diseases, particularly Alzheimer's disease (AD), where defective mitophagy exacerbates hallmark pathologies including Aβ plaque deposition and hyperphosphorylated Tau-driven neurofibrillary tangles. Despite advances, the molecular interplay between FUNDC1 phosphorylation states (e.g., Ser13/Ser17/Tyr18) and AD progression remains poorly defined. This review systematically examines FUNDC1's dual regulatory role in mitophagy, its mechanistic links to Aβ and Tau pathologies, and the therapeutic potential of targeting FUNDC1-associated kinases (e.g., ULK1, CK2) or downstream effectors (e.g., DRP1, OPA1) to counteract mitochondrial dysfunction in AD. By synthesizing recent preclinical and clinical findings, we aim to bridge the gap between FUNDC1 biology and AD therapeutics, highlighting actionable nodes for drug development.

A novel dual CCK/ GLP-1 receptor agonist ameliorates cognitive impairment in 5 × FAD mice by modulating mitophagy via the PINK1/Parkin pathway

To date, no therapeutic drugs available on the market can effectively reverse the progression of Alzheimer's disease (AD). Although Glucagon-like peptide-1 (GLP-1) receptor agonists (RAs) and Cholecystokinin (CCK) RAs have shown some promise in AD research, little is known about the neuroprotective effects of a novel dual CCK/GLP-1 RA in AD. This study sought to examine the effects of the novel dual CCK/GLP-1 RA on cognitive performance in an AD mouse model and to explore the associated mechanisms. Our findings indicate that dual CCK/GLP-1 RA improved cognitive deficits, reduced amyloid-beta (Aβ) accumulation, and alleviated mitochondrial damage in 5 × FAD mice by inducing mitophagy. In an in vitro model of AD cells induced by Aβ, CCK/GLP-1 RA could exert neuroprotective effects by regulating PINK1/Parkin-mediated mitophagy. These data reveal for the first time that the new CCK/GLP-1 RA modulates mitophagy via PINK1/Parkin pathway and enhances cognitive function in the 5 × FAD animal model. Moreover, the performance of the CCK/GLP-1 RA in certain indicators was superior to that of GLP-1 analogue liraglutide, suggesting that it may represent a more promising therapeutic option for AD.

TBK1 alleviates triptolide-induced nephrotoxic injury by up-regulating mitophagy in HK2 cells

Tripterygium wilfordii has been used for a long time to treat autoimmune diseases. Its toxic side effects limit its clinical application. Mitophagy plays a protective role in various diseases. TANK-binding kinase 1 (TBK1) is a mitophagy-promoting molecule. This study aimed to investigate whether TBK1 could alleviate triptolide (TP)-induced nephrotoxicity by regulating mitophagy. To establish TP-induced nephrotoxic injury in animal model, 16 Sprague-Dawley rats were administered with TP by gavage, then renal tissues were collected for hematoxylin and eosin (HE) staining, western blotting and immunofluorescence analysis. To investigate whether up-regulation of TBK1 could alleviate TP-induced nephrotoxic injury and the specific mechanism, HK-2 cells were cultured in vitro, transfected with TBK1-overexpression recombinant lentivirus, then treated with TP. Western blotting, immunofluorescence, flow cytometry, multifunctional microplate detector were used to detect the relevant molecules. Here we found that TP caused kidney function damage, declined mitophagy levels, decreased the expression of TBK1 and mitophagy-related proteins in rats. TP stimulation decreased cell viability, mitochondrial membrane potential, mitophagy-protein, the formation of mito-autophagosomes and mito-autophagolysosomes in HK-2 cells. Upregulating TBK1 could reverse these damages. In summary, TP-induced cell injury had decreased mitophagy levels. Up-regulating TBK1 could increase mitophagy and further alleviate TP-induced cell injury.

Neuron-Derived Extracellular Vesicles: Emerging Regulators in Central Nervous System Disease Progression

The diagnosis and exploration of central nervous system (CNS) diseases remain challenging due to the blood-brain barrier (BBB), complex signaling pathways, and heterogeneous clinical manifestations. Neurons, as the core functional units of the CNS, play a pivotal role in CNS disease progression. Extracellular vesicles (EVs), capable of crossing the BBB, facilitate intercellular and cell-extracellular matrix (ECM) communication, making neuron-derived extracellular vesicles (NDEVs) a focal point of research. Recent studies reveal that NDEVs, carrying various bioactive substances, can exert either pathogenic or protective effects in numerous CNS diseases. Additionally, NDEVs show significant potential as biomarkers for CNS diseases. This review summarizes the emerging roles of NDEVs in CNS diseases, including Alzheimer's disease, depression, traumatic brain injury, schizophrenia, ischemic stroke, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis. It aims to provide a novel perspective on developing therapeutic and diagnostic strategies for CNS diseases through the study of NDEVs.

Tangeretin protects against Aβ1-42-induced toxicity and exploring mitochondria-lysosome interactions in HT22 cells

Tangeretin, a flavonoid from Citri Reticulatae Pericarpium, is known for its neuroprotective effects, but the mechanisms are not fully understood. Alzheimer's disease, a leading neurodegenerative disorder, characterized by amyloid-beta (Aβ) accumulation, represents a significant therapeutic challenge. This study investigates the protective effects of tangeretin against Aβ1-42-induced neurotoxicity using HT22 cells and zebrafish larvae as experimental models. Tangeretin mitigated Aβ1-42-induced cytotoxicity, as evidenced by enhanced cell viability and reduced apoptosis. Tangeretin treatment mitigated Aβ1-42-induced cytotoxicity in HT22 cells, as evidenced by enhanced cell viability and reduced apoptosis. Mechanistically, tangeretin ameliorated mitochondrial dysfunction by reducing mitochondrial fragmentation, decreasing donut-shaped mitochondria, restoring mitochondrial membrane potential, and attenuating reactive oxygen species (ROS) production. Moreover, tangeretin modulated mitochondria-lysosome interactions by promoting mitophagy and normalizing the prolonged mitochondria-lysosome contact induced by Aβ1-42. In zebrafish larvae, Aβ1-42 exposure resulted in developmental malformations, including pericardial and yolk sac edema, elevated ROS levels, increased apoptosis, and impaired neurodevelopment. Tangeretin effectively counteracted these deficits, as revealed by live imaging, supporting its neuroprotective role observed in cellular models. Collectively, our study suggests that tangeretin may serve as a promising protective agent against Aβ1-42-induced neurotoxicity.

Activating autophagy to eliminate toxic protein aggregates with small molecules in neurodegenerative diseases

Neurodegenerative diseases (NDs), such as Alzheimer disease, Parkinson disease, Huntington disease, amyotrophic lateral sclerosis, and frontotemporal dementia, are well known to pose formidable challenges for their treatment due to their intricate pathogenesis and substantial variability among patients, including differences in environmental exposures and genetic predispositions. One of the defining characteristics of NDs is widely reported to be the buildup of misfolded proteins. For example, Alzheimer disease is marked by amyloid beta and hyperphosphorylated Tau aggregates, whereas Parkinson disease exhibits α-synuclein aggregates. Amyotrophic lateral sclerosis and frontotemporal dementia exhibit TAR DNA-binding protein 43, superoxide dismutase 1, and fused-in sarcoma protein aggregates, and Huntington disease involves mutant huntingtin and polyglutamine aggregates. These misfolded proteins are the key biomarkers of NDs and also serve as potential therapeutic targets, as they can be addressed through autophagy, a process that removes excess cellular inclusions to maintain homeostasis. Various forms of autophagy, including macroautophagy, chaperone-mediated autophagy, and microautophagy, hold a promise in eliminating toxic proteins implicated in NDs. In this review, we focus on elucidating the regulatory connections between autophagy and toxic proteins in NDs, summarizing the cause of the aggregates, exploring their impact on autophagy mechanisms, and discussing how autophagy can regulate toxic protein aggregation. Moreover, we underscore the activation of autophagy as a potential therapeutic strategy across different NDs and small molecules capable of activating autophagy pathways, such as rapamycin targeting the mTOR pathway to clear α-synuclein and Sertraline targeting the AMPK/mTOR/RPS6KB1 pathway to clear Tau, to further illustrate their potential in NDs' therapeutic intervention. Together, these findings would provide new insights into current research trends and propose small-molecule drugs targeting autophagy as promising potential strategies for the future ND therapies. SIGNIFICANCE STATEMENT: This review provides an in-depth overview of the potential of activating autophagy to eliminate toxic protein aggregates in the treatment of neurodegenerative diseases. It also elucidates the fascinating interrelationships between toxic proteins and the process of autophagy of "chasing and escaping" phenomenon. Moreover, the review further discusses the progress utilizing small molecules to activate autophagy to improve the efficacy of therapies for neurodegenerative diseases by removing toxic protein aggregates.

Mitochondrial dysfunction in Alzheimer's disease

Alzheimer's disease (AD) is a chronic neurodegenerative disease characterized by progressive cognitive decline and distinct neuropathological features. The absence of a definitive cure presents a significant challenge in neurology and neuroscience. Early clinical manifestations, such as memory retrieval deficits and apathy, underscore the need for a deeper understanding of the disease's underlying mechanisms. While amyloid-β plaques and tau neurofibrillary tangles have dominated research efforts, accumulating evidence highlights mitochondrial dysfunction as a central factor in AD pathogenesis. Mitochondria, essential cellular organelles responsible for energy production necessary for neuronal function become impaired in AD, triggering several cellular consequences. Factors such as oxidative stress, disturbances in energy metabolism, failures in the mitochondrial quality control system, and dysregulation of calcium release are associated with mitochondrial dysfunction. These abnormalities are closely linked to the neurodegenerative processes driving AD development and progression. This review explores the intricate relationship between mitochondrial dysfunction and AD pathogenesis, emphasizing its role in disease onset and progression, while also considering its potential as a biomarker and a therapeutic target.

Tubeimoside I induces mitophagy by activating the PINK1/Parkin/Mfn2 signaling pathway in acute myeloid leukemia cells

Acute myeloid leukemia (AML) is the most prevalent kind of acute leukemia in adults. Despite the availability of new targeted therapies, AML remains connected with a poor prognosis and decreased rate of survival. Tubeimoside I (TBMS1), a critical compound extracted from Bolbostemma paniculatum, has demonstrated potential anticancer effects in lung and colorectal cancers. Nevertheless, the TBMS1 anticancer pathway against AML is still elusive. This study aimed to explore the potential role of TBMS1 in anti-AML and its molecular mechanism. In vitro, TBMS1 treatment suppressed AML cells proliferation, induced apoptosis, and mitochondrial damage, and elevated ROS levels. Network pharmacological analysis suggested, and subsequent studies confirmed, that TBMS1 induced mitophagy in AML cells by modulating the PINK1/Parkin/Mfnh2 signaling pathway, an effect that was effectively reversed following PINK1 knockdown. In vivo, TBMS1 treatment suppressed the proliferation of AML cells after 21 days, improved the survival rates of nude mice, and showed no evident organ toxicity. These evidences suggest that TBMS1 may have significant therapeutic potential in treating AML.

Unraveling the mystery of citrate transporters in Alzheimer's disease: An updated review

A key molecule in cellular metabolism, citrate is essential for lipid biosynthesis, energy production, and epigenetic control. The etiology of Alzheimer's disease (AD), a progressive neurodegenerative illness marked by memory loss and cognitive decline, may be linked to dysregulated citrate transport, according to recent research. Citrate transporters, which help citrate flow both inside and outside of cells, are becoming more and more recognized as possible participants in the molecular processes underlying AD. Citrate synthase (CS), a key enzyme in the tricarboxylic acid (TCA) cycle, supports mitochondrial function and neurotransmitter synthesis, particularly acetylcholine (ACh), essential for cognition. Changes in CS activity affect citrate availability, influencing energy metabolism and neurotransmitter production. Choline, a precursor for ACh, is crucial for neuronal function. Lipid metabolism, oxidative stress reactions, and mitochondrial function can all be affected by aberrant citrate transport, and these changes are linked to dementia. Furthermore, the two main pathogenic characteristics of AD, tau hyperphosphorylation and amyloid-beta (Aβ) aggregation, may be impacted by disturbances in citrate homeostasis. The goal of this review is to clarify the complex function of citrate transporters in AD and provide insight into how they contribute to the development and course of the illness. We aim to provide an in-depth idea of which particular transporters are dysregulated in AD and clarify the functional implications of these dysregulated transporters in brain cells. To reduce neurodegenerative processes and restore metabolic equilibrium, we have also discussed the therapeutic potential of regulating citrate transport. Gaining insight into the relationship between citrate transporters and the pathogenesis of AD may help identify new indicators for early detection and creative targets for treatment. This study offers hope for more potent ways to fight this debilitating illness and is a crucial step in understanding the metabolic foundations of AD.

Efficient strategy for alleviating neuronal apoptosis and oxidative stress damage of Alzheimer's disease through dual targeting BCL-2 gene promoter i-motif and β-amyloid

Alzheimer's disease (AD) is a severe neurodegenerative disorder characterized by abnormal metabolism of β-amyloid (Aβ) precursor proteins and neuronal apoptosis, ultimately leading to cognitive dysfunction. The pathogenesis of AD is complex, and current single-target therapies are not effective in preventing the rapid progression of AD, which highlights the urgent need for developing multi-target drugs. In this study, a series of compounds were synthesized through a multi-targeting ligand strategy. After extensive screening and evaluation, we found a lead compound B14, which showed excellent dual targeting ability for effectively alleviating neuronal apoptosis and oxidative stress damage of AD. In our molecular and cellular level experiments, B14 could target and stabilize the i-motif structure formed on the BCL-2 promoter to upregulate BCL-2 expression, which could also bind to Aβ and inhibit its deposition. In the Aβ1-42-induced cell model, B14 could maintain mitochondrial function and number, regulate intracellular reactive oxygen species (ROS) and Ca2+ metabolism disorders, and effectively reduce Aβ1-42-induced apoptosis. Further studies showed that B14 also exhibited good ability to cross the blood-brain barrier (BBB), which significantly improved learning memory and cognitive deficits, reduced brain Aβ plaques, alleviated inflammation and restored oxidative stress markers in APP/PS1 mice. Our findings provide an innovative strategy of dual targeting BCL-2 promoter i-motif for transcriptional regulation and Aβ aggregation synergistically for mitigating AD pathologies. B14 represents a promising multi-target lead compound with a good potential for further development for AD treatment.

Inhibition of the cGAS-STING pathway via an endogenous copper ion-responsive covalent organic framework nanozyme for Alzheimer's disease treatment

Inhibition of cGAS-STING overactivation has recently emerged as a promising strategy to counteract Alzheimer's disease (AD). However, current cGAS-STING inhibitors as immunosuppressants suffer from instability, non-specific targeting, and innate immune disruption. Here, an endogenous AD brain copper ion-responsive covalent organic framework (COF)-based nanozyme (denoted as TP@PB-COF@NADH) has been designed for targeted inhibition of the cGAS-STING pathway for AD treatment. The effective trapping of excess brain endogenous copper ions by TP@PB-COF@NADH not only inhibits the Cu2+-induced harmful reactive oxygen species (ROS) production which is one of the mediators of cGAS-STING activation, but also activates the nanozyme activity of TP@PB-COF@NADH. Furthermore, the well-prepared nanozyme catalytically generates NAD+ and consumes hydrogen peroxide (H2O2) through second near-infrared (NIR-II) enhanced nicotinamide adenine dinucleotide (NADH) peroxidase (NPX)-like activity, realizing the efficient inhibition of the cGAS-STING pathway and associated neuroinflammation. Moreover, replenishing NAD+ levels efficiently restores mitochondrial function and ATP supply. In vivo studies demonstrate that TP@PB-COF@NADH with NIR-II irradiation significantly improves cognitive function in 3× Tg-AD mice, with a reduction in amyloid-β (Aβ) plaque, neuroinflammation and neuronal damage. Collectively, this work presents a promising approach for AD treatment by using an AD brain harmful excess endogenous copper ion-responsive and efficient nanozyme.

Tooth Loss Leads to Cognitive Impairment and Mitochondrial Disturbance in Wistar Rats

BACKGROUND

The link between tooth loss and cognitive impairment has become increasingly significant. Recent findings suggest that mitochondrial alteration in hippocampal neurons may mediate this relationship.

OBJECTIVE

This study aimed to explore the mediating role of mitochondria in the relationship between tooth loss and cognitive function in Wistar rats.

METHOD

Male Wistar rats (n = 20, 12 weeks old) were randomly divided into tooth extraction (TE) and sham groups. The model was established through upper molar extraction and sham operation respectively. Cognitive evaluations were performed using Morris water maze (MWM) test 8 weeks after the model establishment. Hippocampal neuron morphology was observed. Mitochondrial function was evaluated by ATP level and mitochondrial membrane potential (MMP). Mitophagy assessment involved conducting immunohistochemical and immunofluorescent staining of PTEN-induced kinase 1 (PINK1), Parkin (E3 ubiquitin ligase), translocase of outer mitochondrial membrane 20 (TOMM20), and microtubule-associated protein 1A/1B-light chain 3 (LC3). Additionally, mitophagy protein alterations were analyzed using western blotting.

RESULTS

Memory impairment in the TE group was obvious 8 weeks after model establishment. Substantial hippocampal mitochondrial dysfunction was observed in the TE group, evidenced by notably decreased ATP production, decreased MMP level, and abnormal mitochondrial morphology in the hippocampus. Diminished mitophagy was detected by immunofluorescent staining, and further confirmed by immunostaining and western blotting, indicating diminished mitophagy marker levels in PINK1 and Parkin, along with decreased LC3II/I ratios and elevated Sequestosome-1 (SQSTM1/P62) levels, highlighting hippocampal mitophagy deficiency following tooth loss.

CONCLUSIONS

Tooth loss leads to mitochondrial disturbance and inhibits PINK1/Parkin-mediated mitophagy in hippocampal neurons, inducing cognitive impairment.

CLINICAL RELEVANCE

This study reveals mitochondria may mediate the effect of tooth loss on cognitive function, offering a theoretical basis for the prevention of oral health-associated cognitive decline.

Ceramides may Play a Central Role in the Pathogenesis of Alzheimer's Disease: a Review of Evidence and Horizons for Discovery

While several hypotheses have been proposed to explain the underlying mechanisms of Alzheimer's disease, none have been entirely satisfactory. Both genetic and non-genetic risk factors, such as infections, metabolic disorders and psychological stress, contribute to this debilitating disease. Multiple lines of evidence indicate that ceramides may be central to the pathogenesis of Alzheimer's disease. Tumor necrosis factor-α, saturated fatty acids and cortisol elevate the brain levels of ceramides, while genetic risk factors, such as mutations in APP, presenilin, TREM2 and APOE ε4, also elevate ceramide synthesis. Importantly, ceramides displace sphingomyelin and cholesterol from lipid raft-like membrane patches that connect the endoplasmic reticulum and mitochondria, disturbing mitochondrial oxidative phosphorylation and energy production. As a consequence, the flattening of lipid rafts alters the function of γ-secretase, leading to increased production of Aβ42. Moreover, ceramides inhibit the insulin-signaling cascade via at least three mechanisms, resulting in the activation of glycogen synthase kinase-3 β. Activation of this kinase has multiple consequences, as it further deteriorates insulin resistance, promotes the transcription of BACE1, causes hyperphosphorylation of tau and inhibits the transcription factor Nrf2. Functional Nrf2 prevents apoptosis, mediates anti-inflammatory activity and improves blood-brain barrier function. Thus, various seemingly unrelated Alzheimer's disease risk factors converge on ceramide production, whereas the elevated levels of ceramides give rise to the well-known pathological features of Alzheimer's disease. Understanding and targeting these mechanisms may provide a promising foundation for the development of novel preventive and therapeutic strategies.

Sex and region-specific disruption of autophagy and mitophagy in Alzheimer's disease: linking cellular dysfunction to cognitive decline

Macroautophagy and mitophagy are critical processes in Alzheimer's disease (AD), yet their links to behavioral outcomes, particularly sex-specific differences, are not fully understood. This study investigates autophagic (LC3B-II, SQSTM1) and mitophagic (BNIP3L, BNIP3, BCL2L13) markers in the cortex and hippocampus of male and female 3xTg-AD mice, using western blotting, transmission electron microscopy (TEM), and behavioral tests (novel object recognition and novel object placement). Significant sex-specific differences emerged: female 3xTg-AD mice exhibited autophagosome accumulation due to impaired degradation in the cortex, while males showed fewer autophagosomes, especially in the hippocampus, without significant degradation changes. TEM analyses demonstrated variations in mitochondrial and mitophagosome numbers correlated with memory outcomes. Females had enhanced mitophagy, with higher BNIP3L and BCL2L13 levels, whereas males showed elevated BNIP3 dimers. Cognitive deficits in females correlated with mitochondrial dysfunction in the cortex, while in males, higher LC3B-II levels associated positively with cognitive performance, suggesting protective autophagy effects. Using machine learning, we predicted mitophagosome and mitochondrial numbers based on behavioral data, pioneering a predictive approach to cellular outcomes in AD. These findings underscore the importance of sex-specific regulation of autophagy and mitophagy in AD and support personalized therapeutic approaches targeting these pathways. Integrating machine learning emphasizes its potential to advance neurodegenerative research. Sex-specific differences in autophagy and mitophagy regulation in Alzheimer's disease (AD) are highlighted. Female 3xTg-AD mice show autophagosome accumulation and cognitive deficits, while males exhibit variations in mitophagy markers and behavior.

Cordycepin Ameliorates Kainic Acid-Induced HT22 Cell Neurotoxicity by Activating GPR120-Mediated Mitophagy

BACKGROUND

Mitophagy is important for normal neural activity. Epilepsy is intimately linked to neurotoxicity due to mitochondrial dysfunction. Cordycepin (Cor) has been shown to exert neuroprotective effects. This study aims to investigate whether Cor could mitigate neurotoxicity in epilepsy by modulating mitophagy.

METHODS

In vitro, kainic acid (KA) was utilized to induce cytotoxicity in HT22 cell. Cell viability was assessed using the CCK-8 assay, while cell damage was evaluated through an LDH kit. Flow cytometry was used to assess apoptosis. The expressions of G protein-coupled receptor 120 (GPR120), apoptosis, and mitophagy-related proteins were analyzed by western blot. Inflammatory factors and oxidative stress levels were examined by kits. DCFH-DA staining was applied to observe cellular reactive oxygen species (ROS) levels. The three-dimensional coordinates of GPR120 were retrieved from the PDB database, and molecular docking was performed using AutoDock. Immunofluorescence staining was used to observe mitophagy level.

RESULTS

Cor significantly attenuated KA-induced HT22 cell viability injury and inflammation, while suppressing ROS and oxidative stress levels. Notably, Cor ameliorated the decrease of mitophagy level observed in HT22 cells treated with KA. GPR120 expression was upregulated following KA treatment and further elevated after adding Cor. Cor could bind to GPR120. Interference with GPR120 reversed the ameliorative effects of Cor on KA-induced mitophagy and cytotoxicity in HT22 cells.

CONCLUSION

Overall, Cor significantly alleviated KA-induced HT22 cell neurotoxic damage and oxidative stress. This protective effect may be mediated through GPR120-regulated mitophagy.

Mitochondrial quality control disorder in neurodegenerative disorders: Potential and advantages of traditional Chinese medicines

Neurodegenerative disorders (NDDs) are prevalent chronic conditions characterized by progressive synaptic loss and pathological protein alterations. Increasing evidence suggested that mitochondrial quality control (MQC) serves as the key cellular process responsible for clearing misfolded proteins and impaired mitochondria. Herein, we provided a comprehensive analysis of the mechanisms through which MQC mediates the onset and progression of NDDs, emphasizing mitochondrial dynamic stability, the clearance of damaged mitochondria, and the generation of new mitochondria. In addition, traditional Chinese medicines (TCMs) and their active monomers targeting MQC in NDD treatment have been demonstrated. Consequently, we compiled the TCMs that show great potential in the treatment of NDDs by targeting MQC, aiming to offer novel insights and a scientific foundation for the use of MQC stabilizers in NDD prevention and treatment.

Construction and evaluation of a diagnostic model for Alzheimer's disease based on mitophagy-related genes

Alzheimer's disease (AD) is the most common cause of dementia. Mitophagy fulfills crucial functions in neurodegenerative disorders and neuronal survival but the relationship between mitophagy and AD is unclear. Mitophagy correlation scores between AD samples and control samples were calculated using single-sample GSEA (ssGSEA) based on two datasets from gene expression omnibus (GEO) database. Mitophagy-related genes (MRGs) and differentially expressed genes (DEGs) in AD screened by WGCNA and "limma" package were intersected to take common genes. These overlapping genes were further compressed and used for diagnostic modeling by adopting the recursive feature elimination (RFE) and LASSO analysis. The reliability of the diagnostic model was verified based on the receiver operating characteristic (ROC) curve. Then, a transcription factor (TF)-mRNA regulatory network of these key genes was established. Lastly, ssGSEA was employed to examine the relationship between the identified genes and cellular pathways and immune cell infiltration. AD samples had notably lower mitophagy correlation scores than control samples. A total of 12 MRGs in the module with the greatest mitophagy connection with AD patients were identified. Functional enrichment analysis revealed that the DEGs were significantly enriched in synaptic function-related pathways. Based on GSE122063, a diagnostic prediction model was created and validated using two mitophagy-related genes (YWHAZ and NDE1), showing an area under ROC curve (AUC) greater than 0.7. This confirmed that the diagnostic model had a high predictive value. The TF-mRNA network showed that four TFs, namely, FOXC1, FOXL1, HOXA5 and GATA2, were regulated by both YWHAZ and NDE1 genes. Immune infiltration analysis revealed that NDE1 promoted the infiltration of most immune cells, while YWHAZ mainly inhibited the infiltration of most immune cells. The current findings improved our understanding of mitophagy in AD, contributing to future research and treatment development in AD.

Mitochondria transplantation transiently rescues cerebellar neurodegeneration improving mitochondrial function and reducing mitophagy in mice

Cerebellar ataxia is the primary manifestation of cerebellar degenerative diseases, and mitochondrial dysfunction in Purkinje cells (PCs) plays a critical role in disease progression. In this study, we investigated the feasibility of mitochondria transplantation as a potential therapeutic approach to rescue cerebellar neurodegeneration and elucidate the associated mechanisms. We constructed a conditional Drp1 knockout model in PCs (PCKO mice), characterized by progressive ataxia. Drp1 knockout resulted in pervasive and progressive apoptosis of PCs and significant activation of surrounding glial cells. Mitochondrial dysfunction, which triggers mitophagy, is a key pathogenic factor contributing to morphological and functional damage in PCs. Transplanting liver-derived mitochondria into the cerebellum of 1-month-old PCKO mice improved mitochondrial function, reduced mitophagy, delayed apoptosis of PCs, and alleviated cerebellar ataxia for up to 3 weeks. These findings demonstrate that mitochondria transplantation holds promise as a therapeutic approach for cerebellar degenerative diseases.

The role of n-3-derived specialised pro-resolving mediators (SPMs) in microglial mitochondrial respiration and inflammation resolution in Alzheimer's disease

Alzheimer's disease (AD) is the most common form of dementia globally and is characterised by reduced mitochondrial respiration and cortical deposition of amyloid-β plaques and neurofibrillary tangles comprised of hyper-phosphorylated tau. Despite its characterisation more than 110 years ago, the mechanisms by which AD develops are still unclear. Dysregulation of microglial phagocytosis of amyloid-β may play a key role. Microglia are the major innate immune cell of the central nervous system and are critical responders to pro-inflammatory states. Typically, microglia react with a short-lived inflammatory response. However, a dysregulation in the resolution of this microglial response results in the chronic release of inflammatory mediators. This prolongs the state of neuroinflammation, likely contributing to the pathogenesis of AD. In addition, the microglial specialised pro-resolving mediator (SPM) contribution to phagocytosis of amyloid-β is dysregulated in AD. SPMs are derivatives of dietary n-3 polyunsaturated fatty acids (PUFAs) and potentially represent a strategic target for protection against AD progression. However, there is little understanding of how mitochondrial respiration in microglia may be sustained long term by n-3-derived SPMs, and how this affects their clearance of amyloid-β. Here, we re-evaluate the current literature on SPMs in AD and propose that SPMs may improve phagocytosis of amyloid-β by microglia as a result of sustained mitochondrial respiration and allowing a pro-resolution response.

Role of Tau Protein Hyperphosphorylation in Diabetic Retinal Neurodegeneration

Diabetic retinal neurodegeneration (DRN) is an early manifestation of diabetic retinopathy (DR) characterized by neurodegeneration that precedes microvascular abnormalities in the retina. DRN is characterized by apoptosis of retinal ganglion cells (involves alterations in retinal ganglion cells [RGCs], photoreceptors, amacrine cells and bipolar cells and so on), reactive gliosis, and reduced retinal neuronal function. Tau, a microtubule-associated protein, is a key mediator of neurotoxicity in neurodegenerative diseases, with functions in phosphorylation-dependent microtubule assembly and stabilization, axonal transport, and neurite outgrowth. The hyperphosphorylated tau (p-tau) loses its ability to bind to microtubules and aggregates to form paired helical filaments (PHFs), which further form neurofibrillary tangles (NFTs), leading to abnormal cell scaffolding and cell death. Studies have shown that p-tau can cause degeneration of RGCs in DR, making tau pathology a new pathophysiological model for DR. Here, we review the mechanisms by which p-tau contribute to DRN, including insulin resistance or lack of insulin, mitochondrial damage such as mitophagy impairment, mitochondrial axonal transport defects, mitochondrial bioenergetics dysfunction, and impaired mitochondrial dynamics, Abeta toxicity, and inflammation. Therefore, this article proposes that tau protein hyperphosphorylation plays a crucial role in the pathogenesis of DRN and may serve as a novel therapeutic target for combating DRN.

Forkhead box O-1 regulates the biological behavior of BMP-2-induced human bone mesenchymal stem cells through mitochondrial dynamics and autophagy

This study explored the mechanism by which forkhead box O-1 (FoxO1) modulates the biological behaviors of bone mesenchymal stem cell (BMSC). Human BMSCs were cultured for seven days in Dulbecco's modified Eagle medium (DMEM) containing bone morphogenetic protein-2 (BMP-2) and treated with a short hairpin-FoxO1 plasmid. The study assessed cell proliferation, migration, apoptosis, adenosine triphosphate (ATP) levels, mitochondrial DNA (mtDNA) levels, membrane potential (MMP), autophagy, and the levels of FoxO1, apoptosis-associated proteins, osteogenic differentiation-associated proteins, mitochondrial fusion and fission proteins, and mitochondrial autophagy-related proteins. The cells were also treated with the mitochondrial fusion activator MASM7 and the mitochondrial autophagy activator carbonyl cyanide 3-chlorophenylhydrazone (CCCP). The study evaluated whether mitochondrial dynamics and autophagy activation could rescue the FoxO1 knockdown-induced changes in BMSC biological behaviors, mitochondrial dynamics, and mitochondrial autophagy. BMP-2-induced BMSCs exhibited upregulated FoxO1 expression, enhanced proliferation and migration, and induced osteogenic differentiation, while FoxO1 knockdown inhibited BMP-2-induced BMSC proliferation, migration and osteogenic differentiation, increased apoptosis, and affected mitochondrial dynamics and autophagy. Promoting mitochondrial fusion partially reversed the regulatory effects of FoxO1 downregulation on mitochondrial autophagy and the inhibitory effects of FoxO1 silencing on BMP-2-induced BMSC biological behaviors. Activated mitochondrial autophagy facilitated the homeostasis of mitochondrial dynamics and partially counteracted the inhibitory effects of FoxO1 knockdown on BMP-2-induced BMSC biological behaviors. In conclusion, FoxO1 regulates mitochondrial dynamics and autophagy to modulate the osteogenic differentiation of BMP-2-induced human BMSCs.

Intermittent fasting and neurodegenerative diseases: Molecular mechanisms and therapeutic potential

Neurodegenerative disorders are straining public health worldwide. During neurodegenerative disease progression, aberrant neuronal network activity, bioenergetic impairment, adaptive neural plasticity impairment, dysregulation of neuronal Ca2+ homeostasis, oxidative stress, and immune inflammation manifest as characteristic pathological changes in the cellular milieu of the brain. There is no drug for the treatment of neurodegenerative disorders, and therefore, strategies/treatments for the prevention or treatment of neurodegenerative disorders are urgently needed. Intermittent fasting (IF) is characterized as an eating pattern that alternates between periods of fasting and eating, requiring fasting durations that vary depending on the specific protocol implemented. During IF, depletion of liver glycogen stores leads to the production of ketone bodies from fatty acids derived from adipocytes, thereby inducing an altered metabolic state accompanied by cellular and molecular adaptive responses within neural networks in the brain. At the cellular level, adaptive responses can promote the generation of synapses and neurons. At the molecular level, IF triggers the activation of associated transcription factors, thereby eliciting the expression of protective proteins. Consequently, this regulatory process governs central and peripheral metabolism, oxidative stress, inflammation, mitochondrial function, autophagy, and the gut microbiota, all of which contribute to the amelioration of neurodegenerative disorders. Emerging evidence suggests that weight regulation significantly contributes to the neuroprotective effects of IF. By alleviating obesity-related factors such as blood-brain barrier dysfunction, neuroinflammation, and β-amyloid accumulation, IF enhances metabolic flexibility and insulin sensitivity, further supporting its potential in mitigating neurodegenerative disorders. The present review summarizes animal and human studies investigating the role and underlying mechanisms of IF in physiology and pathology, with an emphasis on its therapeutic potential. Furthermore, we provide an overview of the cellular and molecular mechanisms involved in regulating brain energy metabolism through IF, highlighting its potential applications in neurodegenerative disorders. Ultimately, our findings offer novel insights into the preventive and therapeutic applications of IF for neurodegenerative disorders.

Mitophagy in Neurodegenerative Diseases: Mechanisms of Action and the Advances of Drug Discovery

Neurodegenerative diseases (NDDs), such as Parkinson's disease (PD) and Alzheimer's disease (AD), are devastating brain diseases and are incurable at the moment. Increasing evidence indicates that NDDs are associated with mitochondrial dysfunction. Mitophagy removes defective or redundant mitochondria to maintain cell homeostasis, whereas deficient mitophagy accelerates the accumulation of damaged mitochondria to mediate the pathologies of NDDs. Therefore, targeting mitophagy has become a valuable therapeutic pathway for the treatment of NDDs. Several mitophagy modulators have been shown to ameliorate neurodegeneration in PD and AD. However, it remains to be further investigated for other NDDs. Here, we describe the mechanism and key signaling pathway of mitophagy and summarize the roles of defective mitophagy on the pathogenesis of NDDs. Further, we underline the development advances of mitophagy modulators for PD and AD therapy, discuss the therapeutic challenges and limitations of the existing modulators, and provide guidelines for mitophagy mechanism exploration and drug design.

OAB-14 alleviates mitochondrial impairment through the SIRT3-dependent mechanism in APP/PS1 transgenic mice and N2a/APP cells

Alzheimer's disease (AD) is a progressive degenerative disease that affects a growing number of elderly individuals worldwide. OAB-14, a novel chemical compound developed by our research group, has been approved by the China Food and Drug Administration (FDA) for clinical trials in patients with AD (approval no. YD-OAB-220210). Previous studies have shown that OAB-14 enhances cognitive function in APP/PS1 transgenic mice and ameliorates abnormal mitochondrial morphology in the hippocampus. Mitochondrial dysfunction is a major risk factor for the development of AD, and maintaining healthy mitochondrial morphology and function is essential for improving the pathological changes and symptoms of AD. However, the protective effects of OAB-14 on mitochondria in AD and the underlying mechanisms remain unclear. This study aimed to investigate the protective effects of OAB-14 on the mitochondria of APP/PS1 transgenic mice and N2a/APP cells. Treatment with OAB-14 restored impaired mitochondrial function, mitochondrial dynamics, mitophagy, and mitochondrial DNA (mtDNA) in APP/PS1 transgenic mice and N2a/APP cells. In APP/PS1 transgenic mice and N2a/APP cells, OAB-14-treated elevated the expression and activity of SIRT3, decreased mitochondrial acetylation, and reduced mitochondrial reactive oxygen species (mtROS) levels. OAB-14 also attenuated mitochondrial acetylation, improved mitochondrial dynamics and mitophagy, and mitigated mtDNA damage in a SIRT3-dependent manner. In addition, OAB-14 suppressed mitochondrial Aβ accumulation in the hippocampus of APP/PS1 transgenic mice. This study provides further clarification on the potential therapeutic mechanisms of OAB-14 in the treatment of AD and lays the groundwork for future drug applications.

TREM2 Alleviates Neuroinflammation by Maintaining Cellular Metabolic Homeostasis and Mitophagy Activity During Early Inflammation

AIMS

Inflammation is a pivotal characteristic of neurodegenerative diseases. The triggering receptor expressed on the myeloid cells 2 (TREM2) gene has previously been shown to suppress inflammation by directly inhibiting inflammation-related pathways. Mitochondrial dysfunction has recently emerged as another critical pathological manifestation of neurodegenerative diseases. Although TREM2 is involved in the regulation of cellular energy metabolism and mitochondrial autophagy, its role in the relationship between inflammation and mitochondrial autophagy remains unclear.

METHODS

In this study, we generated TREM2-overexpressing BV-2 cells and established a neuroinflammatory model with LPS. We compared these cells with wild-type cells in terms of inflammation, metabolism, autophagy, and mitochondria using methods such as RT-qPCR, Western blotting, immunocytochemistry, transmission electron microscopy, and flow cytometry.

RESULTS

Microglia overexpressing TREM2 exhibited increased resistance to inflammation. Additionally, these cells inhibited the metabolic reprogramming that occurs early in LPS-induced inflammation, reduced ROS release, mitigated mitochondrial damage, maintained a certain level of autophagic activity, and cleared damaged mitochondria. Consequently, they alleviated the inflammation caused by the mitochondrial barrier.

CONCLUSIONS

ur results suggest that TREM2 can alleviate inflammation by maintaining cellular metabolic homeostasis and mitochondrial autophagy activity.

Bioinformatics insights into mitochondrial and immune gene regulation in Alzheimer's disease

BACKGROUND

There is growing evidence that the pathogenesis of Alzheimer's disease is closely linked to the resident innate immune cells of the central nervous system, including microglia and astrocytes. Mitochondrial dysfunction in microglia has also been reported to play an essential role in the pathogenesis of AD and other neurological diseases. Therefore, finding the mitochondrial and immune-related gene (MIRG) signatures in AD can be significant in diagnosing and treating AD.

METHODS

In this study, the intersection of the differentially expressed genes (DEGs) from the GSE109887 cohort, immune-related genes (IRGs) obtained from WGCNA analysis, and mitochondria-related genes (MRGs) was taken to identify mitochondria-immune-related genes (MIRGs). Then, using machine learning algorithms, biomarkers with good diagnostic value were selected, and a nomogram was constructed. Subsequently, we further analyzed the signaling pathways and potential biological mechanisms of the biomarkers through gene set enrichment analysis, prediction of transcription factors (TFs), miRNAs, and drug prediction.

RESULTS

Using machine learning algorithms, five biomarkers (TSPO, HIGD1A, NDUFAB1, NT5DC3, and MRPS30) were successfully identified, and a nomogram model with strong diagnostic ability and accuracy (AUC > 0.9) was constructed. In addition, single-gene enrichment analysis revealed that NDUFAB1 was significantly enriched in pathways associated with diseases, such as Alzheimer's and Parkinson's, providing valuable insights for future clinical research on Alzheimer's in the context of mitochondrial-immune interactions. Interestingly, brain tissue pathology showed neuronal atrophy and demyelination in AD mice, along with a reduction in Nissl bodies. Furthermore, the escape latency of AD mice was significantly longer than that of the control group. After platform removal, there was a notable increase in the path complexity and time required to reach the target quadrant, suggesting a reduction in spatial memory capacity in AD mice. Moreover, qRT-PCR validation confirmed that the mRNA expression of the five biomarkers was consistent with bioinformatics results. In AD mice, TSPO expression was increased, while HIGD1A, NDUFAB1, NT5DC3, and MRPS30 expressions were decreased. However, peripheral blood samples did not show expression of HIGD1A or MRPS30. These findings provide new insights for research on Alzheimer's disease in the context of mitochondrial-immune interactions, further exploring the pathogenesis of Alzheimer's disease and offering new perspectives for the clinical development of novel drugs.

CONCLUSIONS

Five mitochondrial and immune biomarkers, i.e., TSPO, HIGD1A, NDUFAB1, NT5DC3, and MRPS30, with diagnostic value in Alzheimer's disease, were screened by machine-learning algorithmic models, which will be a guide for future clinical research of Alzheimer's disease in the mitochondria-immunity-related direction.

Transcriptome analysis of early- and late-onset Alzheimer's disease in Korean cohorts

INTRODUCTION

The molecular mechanisms underlying early-onset Alzheimer's disease (EOAD) and late-onset Alzheimer's disease (LOAD) remain incompletely understood, particularly in Asian populations.

METHODS

RNA-sequencing was carried out on blood samples from 248 participants in the Seoul National University Bundang Hospital cohort to perform differential gene expression (DGE) and weighted gene co-expression network analysis. Findings were replicated in an independent Korean cohort (N = 275).

RESULTS

DGE analysis identified 18 and 88 dysregulated genes in EOAD and LOAD, respectively. Network analysis identified a LOAD-associated module showing a significant enrichment in pathways related to mitophagy, 5' adenosine monophosphate-activated protein kinase signaling, and ubiquitin-mediated proteolysis. In the replication cohort, downregulation of SMOX and PLVAP in LOAD was replicated, and the LOAD-associated module was highly preserved. In addition, SMOX and PLVAP were associated with brain amyloid beta deposition.

DISCUSSION

Our findings suggest distinct molecular signatures for EOAD and LOAD in a Korean population, providing deeper understanding of their diagnostic potential and molecular mechanisms.

HIGHLIGHTS

Analysis identified 18 and 88 dysregulated genes in early-onset Alzheimer's disease (EOAD) and late-onset Alzheimer's disease (LOAD), respectively. Expression levels of SMOX and PLVAP were downregulated in LOAD. Expression levels of SMOX and PLVAP were associated with brain amyloid beta deposition. Pathways including mitophagy and 5' adenosine monophosphate-activated protein kinase signaling were enriched in a LOAD module. A LOAD module was highly preserved across two independent cohorts.

Neuroprotective effects of chitinase-1 and calcitonin gene-related peptide on Alzheimer's disease by promoting lysosomal function

BACKGROUND

The amyloid cascade hypothesis still dominates in Alzheimer's disease (AD), and the acceleration of the clearance efficiency of amyloid-β (Aβ) has been always considered as an effective treatment option to slow the occurrence and progression of AD.

OBJECTIVE

This study aims to explore the role of zkscan3 and its related pathways in AD of the microglia-mediated pathogenesis, and whether the combined effect of drugs can exert neuroprotective function.

METHODS

N9 mouse microglia and HT-22 mouse hippocampal neurons were randomly divided into 6 groups, qRT-PCR technique was used to detect the gene expression level of zkscan3 and the genes related to lysosome generation and function. Fourteen C57 mice were randomly divided into two groups, and drug intervention model mice were randomly selected to establish from the AD group. Transmission electron microscope was used to detect the cell status and lysosome function in the hippocampus together with the other two groups.

RESULTS

Compared with the AD model group, the gene expression of zkscan3 in the drug intervention group was downregulated, and the degree of neuronal injury in the hippocampus was reduced, the structure and number of synapses were improved, and the function of intracellular lysosome was enhanced.

CONCLUSIONS

Zkscan3 and its related genes play a vital role in the development of AD. CGRP and CHIT-1, as a combined intervention, imparts effects through zkscan3-related pathways to improve lysosomal function and exert certain neuroprotective effects.

Penehyclidine hydrochloride activates PARK2 and modulates ubiquitination of AIFM1 to rescue renal tubular injury in diabetic kidney disease

BACKGROUND

Renal tubular injury (RTI) is one of the key characteristics of diabetic nephropathy (DN). Penehyclidine hydrochloride (PHC) was an anticholinergic drug with renoprotective effects, but its specific mechanism in the treatment of DN was still unclear.

METHODS

We treated different diabetic mouse models and high glucose-induced RTI models by PHC. Histological analyses were performed using flow cytometry and staining, and ELISA evaluated the ROS, apoptosis, and related markers under different treatments. The molecular interactions were analyzed by ChIP, dual-luciferase reporter, and CoIP.

RESULTS

PHC alleviated RTI by activating mitophagy and inhibiting apoptosis, and the protective effect could be rescued by PARK2 knockdown. Nrf2 bound to the promoter region of PARK2 and promoted its expression. PHC reduced the level of apoptosis by reducing the degree of nuclear translocation of AIFM1, which was rescued by PARK2 knockdown. PARK2 knockdown reduced the non-degradative ubiquitination of AIFM1, thus promoting its nuclear translocation and ultimately facilitating renal tubular cells (RTCs) apoptosis. The over-expression of AIFM1 rescued the RTCs apoptosis antagonized by PHC.

CONCLUSIONS

PHC activated Nrf2 to up-regulate PARK2 transcription to induce mitophagy and inhibit apoptosis mediated by nuclear translocation of AIFM1 through promoting non-degradative ubiquitination of AIFM1, ultimately rescuing RTI in DN.

Comparative outcomes of systemic diseases in people with type 2 diabetes, or obesity alone treated with and without GLP-1 receptor agonists: a retrospective cohort study from the Global Collaborative Network : Author list

BACKGROUND

Glucagon-like peptide-1 receptor agonists (GLP-1RAs) are increasingly used to manage type 2 diabetes (T2D) and obesity. Despite their recognized benefits in glycemic control and weight management, their impact on broader systemic has been less explored.

OBJECTIVE

This study aimed to evaluate the impact of GLP-1RAs on a variety of systemic diseases in people with T2D or obesity.

METHODS

We conducted a retrospective cohort study using data from the Global Collaborative Network, accessed through the TriNetX analytics platform. The study comprised two primary groups: individuals with T2D and those with obesity. Each group was further divided into subgroups based on whether they received GLP-1RA treatment or not. Data were analyzed over more than a 5-year follow-up period, comparing incidences of systemic diseases; systemic lupus erythematosus (SLE), systemic sclerosis (SS), rheumatoid arthritis (RA), ulcerative colitis (UC), crohn's disease (CD), alzheimer's disease (AD), parkinson's disease (PD), dementia, bronchial asthma (BA), osteoporosis, and several cancers.

RESULTS

In the T2D cohorts, GLP-1RA treatment was associated with significantly lower incidences of several systemic and metabolic conditions as compared to those without GLP-1RA, specifically, dementia (Risk Difference (RD): -0.010, p < 0.001), AD (RD: -0.003, p < 0.001), PD (RD: -0.002, p < 0.001), and pancreatic cancer (RD: -0.003, p < 0.001). SLE and SS also saw statistically significant reductions, though the differences were minor in magnitude (RD: -0.001 and - 0.000 respectively, p < 0.001 for both). Conversely, BA a showed a slight increase in risk (RD: 0.002, p < 0.001).

CONCLUSIONS

GLP-1RAs demonstrate potential benefits in reducing the risk of several systemic conditions in people with T2D or obesity. Further prospective studies are needed to confirm these effects fully and understand the mechanisms.

Cilostazol counteracts mitochondrial dysfunction in hepatic encephalopathy rat model: Insights into the role of cAMP/AMPK/SIRT1/ PINK-1/parkin hub and p-CREB /BDNF/ TrkB neuroprotective trajectory

A devasting stage of chronic hepatic dysfunction is strictly correlated with neurological impairment, signifying hepatic encephalopathy (HE). HE is a multifactorial condition; therefore, hyperammonemia, oxidative stress, neuroinflammation, and mitochondrial dysfunction interplay in HE's progressive development. Cilostazol (Cilo) has shown promising neuroprotective and hepatoprotective effectiveness in different neuronal and hepatic disorders; however, its efficiency against HE hasn't yet been explored. This study aimed to investigate the protective role of Cilo against thioacetamide (TAA)-induced HE in rats targeting mitochondrial dysfunction via modulation of Adenosine monophosphate-activated protein kinase (AMPK)/Silent information regulator 1 (SIRT1) dependent pathways. Rats were allocated into three groups: the normal control group, the TAA group received (100 mg/kg, three times per week, for six weeks) to induce HE, and the Cilo group received (Cilo 100 mg/kg/day for six weeks, oral gavage) concurrently with TAA. Cilo counteracted HE indicated in the enhancement of cognitive impairment and the motor performance of rats (P < 0.0001), modulation AMPK/SIRT1signaling pathway causing reduction of NF-kB p65 (P < 0.0001) evoked inflammation along with histopathological alterations and glial fibrillary acidic protein (GFAP) immunoreactivity (P < 0.0001), restoration nuclear factor E2-related factor 2 (Nrf2) (P < 0.0001) antioxidant effects, reduction of Bax and elevation of Bcl2 immunoreactivity (P < 0.0001) in addition to boosting mitochondrial biogenesis by upregulation of PTEN-induced kinase-1 (PINK-1)/Parkin (P < 0.0001)and restoration of Brain-derived neurotrophic factor (BDNF) (P = 0.0002)/tropomyosin-related kinase B (TrkB) (P < 0.0001)/cAMP response element-binding (CREB) (P < 0.0001) neuroprotective axis. Collectively, Cilo activates the SIRT1 trajectory to abridge mitochondrial dysfunction invigorated in the HE rat model via restoration of mitochondrial hemostasis.

Autophagy, aging, and age-related neurodegeneration

Autophagy is a conserved mechanism that degrades damaged or superfluous cellular contents and enables nutrient recycling under starvation conditions. Many neurodegeneration-associated proteins are autophagy substrates, and autophagy upregulation ameliorates disease in many animal models of neurodegeneration by enhancing the clearance of toxic proteins, proinflammatory molecules, and dysfunctional organelles. Autophagy inhibition also induces neuronal and glial senescence, a phenomenon that occurs with increasing age in non-diseased brains as well as in response to neurodegeneration-associated stresses. However, aging and many neurodegeneration-associated proteins and mutations impair autophagy. This creates a potentially detrimental feedback loop whereby the accumulation of these disease-associated proteins impairs their autophagic clearance, facilitating their further accumulation and aggregation. Thus, understanding how autophagy interacts with aging, senescence, and neurodegenerative diseases in a temporal, cellular, and genetic context is important for the future clinical application of autophagy-modulating therapies in aging and neurodegeneration.

Arrestin-3 binds parkin and enhances parkin-dependent mitophagy

Arrestins were discovered for their role in homologous desensitization of G-protein-coupled receptors (GPCRs). Later non-visual arrestins were shown to regulate several signaling pathways. Some of these pathways require arrestin binding to GPCRs, the regulation of others is receptor independent. Here, we demonstrate that arrestin-3 binds the E3 ubiquitin ligase parkin via multiple sites, preferentially interacting with its RING0 domain. Identification of the parkin domains involved suggests that arrestin-3 likely relieves parkin autoinhibition and/or stabilizes the enzymatically active "open" conformation of parkin. Arrestin-3 binding enhances ubiquitination by parkin of the mitochondrial protein mitofusin-1 and facilitates parkin-mediated mitophagy in HeLa cells. Furthermore, arrestin-3 and its mutant with enhanced parkin binding rescue mitofusin-1 ubiquitination and mitophagy in the presence of the Parkinson's disease-associated R275W parkin mutant, which is defective in both functions. Thus, modulation of parkin activity via arrestin-3 might be a novel strategy of anti-parkinsonian therapy.

Does photobiomodulation alter mitochondrial dynamics?

Mitochondrial dysfunction is one of the leading causes of disease development. Dysfunctional mitochondria limit energy production, increase reactive oxygen species generation, and trigger apoptotic signals. Photobiomodulation is a noninvasive, nonthermal technique involving the application of monochromatic light with low energy density, inducing non-thermal photochemical effects at the cellular level, and it has been used due to its therapeutic potential. This review focuses on the mitochondrial dynamic's role in various diseases, evaluating the possible therapeutic role of low-power lasers (LPL) and light-emitting diodes (LED). Studies increasingly support that mitochondrial dysfunction is correlated with severe neurodegenerative diseases such as Parkinson's, Huntington's, Alzheimer's, and Charcot-Marie-Tooth diseases. Furthermore, a disturbance in mitofusin activity is also associated with metabolic disorders, including obesity and type 2 diabetes. The effects of PBM on mitochondrial dynamics have been observed in cells using a human fibroblast cell line and in vivo models of brain injury, diabetes, spinal cord injury, Alzheimer's disease, and skin injury. Thus, new therapies aiming to improve mitochondrial dynamics are clinically relevant. Several studies have demonstrated that LPL and LED can be important therapies to improve health conditions when there is dysfunction in mitochondrial dynamics.

Effect of Dietary Ketosis and Nicotinamide Riboside on Hippocampal Krebs Cycle Intermediates and Mitochondrial Energetics in a DNA Repair-Deficient 3xTg/POLβ+/- Alzheimer Disease Mouse Model

Alzheimer disease is a neurodegenerative pathology-modifying mitochondrial metabolism with energy impairments where the effects of biological sex and DNA repair deficiencies are unclear. We investigated the therapeutic potential of dietary ketosis alone or with supplemental nicotinamide riboside (NR) on hippocampal intermediary metabolism and mitochondrial bioenergetics in older male and female wild-type (Wt) and 3xTgAD-DNA polymerase-β-deficient (3xTg/POLβ+/-) (AD) mice. DNA polymerase-β is a key enzyme in DNA base excision repair (BER) of oxidative damage that may also contribute to mitochondrial DNA repair. Metabolic alterations imparted by ketosis and/or NR were assessed in 16 male and female groups, 4 Wt and 4 AD. At 73 weeks of age, mice were divided into: (A) carbohydrate diet (Carb); (B) Carb diet with NR (Carb-NR); (C) Ket diet (Ket); and (D) Ket diet with NR (Ket-NR) groups and remained on their respective treatments for 12 weeks. Mice were euthanized and hippocampi were rapidly removed and frozen. Glycolytic and TCA cycle intermediates were determined by quantitative GC-MS and the ratios of the mitochondrial free [NADox]/[NADHred] and coenzyme ubiquinone (CoQ/CoQH2) couples and the Gibbs free energy of the Complex I-II system of the electron transport chain (ETC) (∆ G mitochondrial Complex I - II ' $$ \Delta {G}_{\mathrm{mitochondrial}\ \mathrm{Complex}\ \mathrm{I}-\mathrm{II}}^{\prime } $$ ) were calculated from selected metabolites. Mice in Groups C and D had elevated blood ketones (1-2 mM). In most groupings, male mice had higher concentrations of TCA cycle intermediates than females. Moreover, higher concentrations of fumarate in Wt males were associated with elevations in the ΔG' of Complex I-II compared to females. In Wt males, NR treatments were associated with elevated concentrations of α-ketoglutarate and malate and linked to increased energy of Complex I-II. In AD males, both NR treatment and dietary ketosis restored the ΔG' of Complex I-II, where the ratio of the CoQ/CoQH2 couple was oxidized and the [NADox]/[NADHred] couple was reduced. In AD females, only mice in the Ket diet group had a sufficiently reduced [NADox]/[NADHred] couple to restore the free energy profile.

Mitostasis in age-associated neurodegeneration

Mitochondria are essential organelles that play crucial roles in various metabolic and signalling pathways. Proper neuronal function is highly dependent on the health of these organelles. Of note, the intricate structure of neurons poses a critical challenge for the transport and distribution of mitochondria to specific energy-intensive domains, such as synapses and dendritic appendages. When faced with chronic metabolic challenges and bioenergetic deficits, neurons undergo degeneration. Unsurprisingly, disruption of mitostasis, the process of maintaining cellular mitochondrial content and function within physiological limits, has been implicated in the pathogenesis of several age-associated neurodegenerative disorders. Indeed, compromised integrity and metabolic activity of mitochondria is a principal hallmark of neurodegeneration. In this review, we survey recent findings elucidating the role of impaired mitochondrial homeostasis and metabolism in the onset and progression of age-related neurodegenerative disorders. We also discuss the importance of neuronal mitostasis, with an emphasis on the major mitochondrial homeostatic and metabolic pathways that contribute to the proper functioning of neurons. A comprehensive delineation of these pathways is crucial for the development of early diagnostic and intervention approaches against neurodegeneration.

A Mitochondria-Targeting and Peroxynitrite-Activatable Ratiometric Fluorescent Probe for Precise Tracking of Oxidative Stress-Induced Mitophagy

Mitochondria are the energy factory of cells and can be easily damaged by reactive oxygen species (ROS) because of the frequent occurrence of oxidative stress. Abnormality in mitophagy is often associated with many diseases including inflammation, cancer, and aging. While previously developed fluorescent probes mainly focus on detecting just ROS or mitophagy, quite rare studies have endeavored to comprehensively capture the entire mitophagic process, encompassing both the production of ROS and the induction of mitophagy. Herein, we report a new ratiometric fluorescent probe NA-DP for tracking peroxynitrite (ONOO-) as well as the subsequent oxidative stress-induced mitophagy. To a naphthalimide-based dye, an ONOO--responsive diphenyl phosphinate moiety and the mitochondria-targeting triphenylphosphonium group were attached. The probe showed a highly selective response to ONOO- through an addition-elimination reaction with diphenyl phosphinate. Owing to its outstanding pH stability and organelle-targeting ability, NA-DP was successfully used to detect mitophagy induced by oxidative stress after the generation of ONOO-. In the meantime, the probe was also used to track starvation-induced mitophagy and indicate that starvation-induced mitophagy is independent of ONOO-. Therefore, NA-DP has the ability to precisely track oxidative stress-induced mitophagy by distinguishing it from starvation-induced mitophagy. This study offers a new chemical tool to study the relationship between ROS generation and mitophagy.