β-Asarone improves learning and memory in Aβ1-42-induced Alzheimer's disease rats by regulating PINK1-Parkin-mediated mitophagy

Protective effects of licofelone on scopolamine-induced spatial learning and memory impairment by enhancing parkin-dependent mitophagy and promotion of neural regeneration and in adult mice

Inhibition of COX and LOX could contribute to memory formation and prevention of neurodegeneration, by alleviation of neuroinflammation and improvement of mitochondrial homeostasis. We aimed to assess the effect of licofelone, a dual COX and 5-LOX inhibitor on memory formation, neural apoptosis, neural regeneration, and mitophagy in acute and chronic dosages, given that licofelone could regulate nitric oxide levels. Y-maze and Passive Avoidance tests were used to evaluate memory function in NMRI mice using the EthoVision setting, following scopolamine administration (1 mg/kg, i.p.) as an acute amnestic drug. Hippocampi were used to evaluate the levels of apoptosis via TUNEL assay, neural regeneration via immunohistochemistry method detecting doublecortin and nestin, and mitophagy via Western blot of mitophagy proteins Parkin and ATG5. While acute high-dose licofelone (20 mg/kg) could reverse amnestic effects of scopolamine in passive avoidance test (p = 0.0001), Chronic licofelone (10 mg/kg for 10 consecutive days) could improve performance in Y-maze (p = 0.0007). Molecular analysis revealed that the chronic form of the drug could enhance neural regeneration in CA1 and SGZ regions, reset mitophagy levels as much as the healthy state, and reduce apoptosis rate. Licofelone appears to show a desirable anti-amnestic profile in a low dose chronically; it is hence recommended for future clinical studies on the prevention of neuroinflammation and memory deficit.

The interplay between mitochondrial dynamics and autophagy: From a key homeostatic mechanism to a driver of pathology

The complex relationship between mitochondrial dynamics and autophagy illustrates how two cellular housekeeping processes are intimately linked, illuminating fundamental principles of cellular homeostasis and shedding light on disparate pathological conditions including several neurodegenerative disorders. Here we review the basic tenets of mitochondrial dynamics i.e., the concerted balance between fusion and fission of the organelle, and its interplay with macroautophagy and selective mitochondrial autophagy, also dubbed mitophagy, in the maintenance of mitochondrial quality control and ultimately in cell viability. We illustrate how conditions of altered mitochondrial dynamics reverberate on autophagy and vice versa. Finally, we illustrate how altered interplay between these two key cellular processes participates in the pathogenesis of human disorders affecting multiple organs and systems.

Unraveling mitochondrial dysfunction: comprehensive perspectives on its impact on neurodegenerative diseases

Neurodegenerative diseases represent a significant challenge to modern medicine, with their complex etiology and progressive nature posing hurdles to effective treatment strategies. Among the various contributing factors, mitochondrial dysfunction has emerged as a pivotal player in the pathogenesis of several neurodegenerative disorders. This review paper provides a comprehensive overview of how mitochondrial impairment contributes to the development of neurodegenerative diseases including Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis, driven by bioenergetic defects, biogenesis impairment, alterations in mitochondrial dynamics (such as fusion or fission), disruptions in calcium buffering, lipid metabolism dysregulation and mitophagy dysfunction. It also covers current therapeutic interventions targeting mitochondrial dysfunction in these diseases.

Effects of β-asarone on spatial learning and memory impairment by exhaustive exercise-induced fatigue: Role of NR-CaMKII-ERK/CREB signal in hippocampus of rats

OBJECTIVE

It is to investigate the effects of β-asarone on learning and memory, hippocampal morphology, synaptophysin (SYP) and postsynaptic density 95(PSD95) protein expression, N-methyl-D-aspartic acid receptor 2B (NR2B)- Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII) - Extracellular signal-regulated kinase (ERK) / Cyclic-AMP response element binding protein (CREB) signal in hippocampus of rats with exhaustive exercise-induced fatigue.

METHODS

Fifty Sprague-Dawley male rats were randomly divided into five groups: normal group, exercise group, exercise and β-asarone (2.5, 10, 40 mg/kg)-treated groups. The learning and memory in rats were tested by Morris water maze experiment. We measured the hippocampal morphology by Nissl staining. The levels of SYP, PSD95, NR2B, CaMKII, ERK1/2, CREB, p-NR2B, p-CaMKII, p-ERK1/2 and p-CREB expression were measured by western blot analysis.

RESULTS

The results demonstrated that β-asarone (10, 40 mg/kg) treatment significantly decreased the latency to find the platform, increased the time spent in the target quadrant and the number of crossing the platform of rats with exhaustive exercise-induced fatigue. β-asarone (10, 40 mg/kg) treatment increased the cell density in the hippocampus CA1 region, significantly up-regulated NR2B-CaMKII-ERK/CREB signal and improved the protein expression levels of SYP and PSD95 in hippocampus of rats with exhaustive exercise-induced fatigue.

CONCLUSIONS

It suggests that β-asarone could improve learning and memory of rats with exhaustive exercise-induced fatigue. The mechanism might be related to β-asarone protecting the morphology of hippocampus, increasing the protein expression levels of SYP and PSD95 and up-regulating NR2B-CaMKII-ERK/CREB signal in hippocampus of rats with exhaustive exercise-induced fatigue.

Mitophagy and cGAS-STING crosstalk in neuroinflammation

Mitophagy, essential for mitochondrial health, selectively degrades damaged mitochondria. It is intricately linked to the cGAS-STING pathway, which is crucial for innate immunity. This pathway responds to mitochondrial DNA and is associated with cellular stress response. Our review explores the molecular details and regulatory mechanisms of mitophagy and the cGAS-STING pathway. We critically evaluate the literature demonstrating how dysfunctional mitophagy leads to neuroinflammatory conditions, primarily through the accumulation of damaged mitochondria, which activates the cGAS-STING pathway. This activation prompts the production of pro-inflammatory cytokines, exacerbating neuroinflammation. This review emphasizes the interaction between mitophagy and the cGAS-STING pathways. Effective mitophagy may suppress the cGAS-STING pathway, offering protection against neuroinflammation. Conversely, impaired mitophagy may activate the cGAS-STING pathway, leading to chronic neuroinflammation. Additionally, we explored how this interaction influences neurodegenerative disorders, suggesting a common mechanism underlying these diseases. In conclusion, there is a need for additional targeted research to unravel the complexities of mitophagy-cGAS-STING interactions and their role in neurodegeneration. This review highlights potential therapies targeting these pathways, potentially leading to new treatments for neuroinflammatory and neurodegenerative conditions. This synthesis enhances our understanding of the cellular and molecular foundations of neuroinflammation and opens new therapeutic avenues for neurodegenerative disease research.

Progress in mitochondrial and omics studies in Alzheimer's disease research: from molecular mechanisms to therapeutic interventions

Alzheimer's disease (Alzheimer's disease, AD) is a progressive neurological disorder characterized by memory loss and cognitive impairment. It is characterized by the formation of tau protein neurofibrillary tangles and β-amyloid plaques. Recent studies have found that mitochondria in neuronal cells of AD patients exhibit various dysfunctions, including reduced numbers, ultrastructural changes, reduced enzyme activity, and abnormal kinetics. These abnormal mitochondria not only lead to the loss of normal neuronal cell function, but are also a major driver of AD progression. In this review, we will focus on the advances of mitochondria and their multi-omics in AD research, with particular emphasis on how mitochondrial dysfunction in AD drives disease progression. At the same time, we will focus on summarizing how mitochondrial genomics technologies have revealed specific details of these dysfunctions and how therapeutic strategies targeting mitochondria may provide new directions for future AD treatments. By delving into the key mechanisms of mitochondria in AD related to energy metabolism, altered kinetics, regulation of cell death, and dysregulation of calcium-ion homeostasis, and how mitochondrial multi-omics technologies can be utilized to provide us with a better understanding of these processes. In the future, mitochondria-centered therapeutic strategies will be a key idea in the treatment of AD.

New Value of Acorus tatarinowii/gramineus Leaves as a Dietary Source for Dementia Prevention

The rhizomes of Acorus tatarinowii Schott and Acorus gramineus Solander are widely used for treating amnesia in traditional Chinese medicine. In contrast, their leaves are usually discarded without their medicinal properties being known. Here, we found that the hot water extract of leaves improved cognition and tau pathology in model mice of frontotemporal dementia, similar to or even better than that of rhizomes. To explore the optimal method of processing, we made three preparations from dried leaves: hot water extract, extraction residue, and non-extracted simple crush powder. Among them, the simple crush powder had the strongest effect on tauopathy in mice. The crush powder also ameliorated Aβ and α-synuclein pathologies and restored cognition in mouse models of Alzheimer's disease and dementia with Lewy bodies. These findings suggest the potential of Acorus tatarinowii/gramineus leaves as a dietary source for dementia prevention and reveal that simple crushing is a better way to maximize their efficacy.

Inhibitory effects of β-asarone on lncRNA BACE1-mediated induction of autophagy in a model of Alzheimer's disease

The primary aim of this study was to examine the correlation between the formation of Aβ plaques and autophagy, which is regulated by β-asarone and the lncRNA BACE1-AS. Additionally, the study sought to explore potential targets of the drug in inhibiting the deposition of toxic AD-related proteins and restoring impaired mitochondrial and autophagic functions. SHY5Y cells were utilized to construct a stable Alzheimer's disease (AD) model, followed by the utilization of interference and overexpression lentiviruses targeting BACE1-AS to establish a cell model. The cells were categorized into five groups, including a normal group, siRNA/BACE1 group, and β-asarone group. The fluorescence quantitative PCR technique was employed to assess the disparity in BACE1 mRNA expression, while changes in immunofluorescence (IF) were observed to determine the stable interference titre and action time of the lentiviruses. Additionally, western blotting (WB) and fluorescence quantitative PCR were employed to evaluate the expression of proteins and mRNAs associated with AD and autophagy. The findings demonstrated a significant elevation in BACE1 expression levels in brain tissue among individuals with AD compared to those without the condition. Moreover, the results indicated that the introduction of β-asarone led to an increase in the expression of the BACE1-AS gene in the cell group transfected with plasmid H12732. Furthermore, it was observed that β-asarone enhanced the expression levels of shRNA and BACE1 after 72 h. In contrast, β-asarone suppressed the expression of PS1, Aβ, BACE1, APP, and p62, while promoting the expression of syn, LC3 I/II, and Beclin-1. Based on these findings, it can be concluded that β-Asarone exerts a comprehensive influence on the expression of proteins associated with AD and synaptic function. β-Asarone exhibits the potential to mitigate Aβ deposition by impeding the expression of lncBACE1, thereby facilitating autophagy through the suppression of BACE1's inhibitory impact on autophagy. This complements the self-enhancing effect of autophagy.

Classic Famous Prescription Kai-Xin-San Ameliorates Alzheimer's Disease via the Wnt/β-Catenin Signaling Pathway

Kai-Xin-San (KXS) is a classic famous prescription composed of Polygalae Radix, Ginseng Radix et Rhizoma, Acori Tatarinowii Rhizoma, and Poria. Clinically, KXS is effective in treating amnesia and regulating cognitive dysfunction of Alzheimer's disease (AD), whereas its mechanism of action is still unclear. In this study, the AD model rats were established by combining intraperitoneal injection of D-galactose (150 mg/kg/day) and intracerebral injection of Aβ25-35 (10 μL) to investigate the meliorative effect of KXS on AD and explore its mechanism. After 1-month KXS treatment, Morris water maze test showed that different doses of KXS all improved the cognitive impairment of AD rats. The results of hematoxylin and eosin staining, Nissl staining, and Tunnel staining showed that the neuron injury in the hippocampal CA1 region of the AD rats was markedly improved after KXS treatment. Concurrently, KXS reversed the levels of biochemical indexes of AD rats. Furthermore, the protein expressions of Wnt1 and β-catenin in KXS groups were remarkably increased, while the expressions of Bax and caspase-3 were significantly decreased. Besides, KXS-medicated serum reduced the levels of tumor necrosis factor-α, interleukin-1β, and reactive oxygen species and regulated the protein expressions of β-catenin, glycogen synthase kinase-3β (GSK-3β), p-GSK-3β, Bax, and caspase-3 in Aβ25-35-induced pheochromocytoma cells. Most importantly, this effect was attenuated by the Wnt inhibitor IWR-1. Our results suggest that KXS improves cognitive and memory function of AD rats, and its neuroprotective mechanism may be mediated through the Wnt/β-catenin signaling pathway.

Therapeutic potential of natural products against Alzheimer's disease via autophagic removal of Aβ

The pathological features of Alzheimer's disease (AD), a progressive neurodegenerative disorder, include the deposition of extracellular amyloid beta (Aβ) plaques and intracellular tau neurofibrillary tangles. A decline in cognitive ability is related to the accumulation of Aβ in patients with AD. Autophagy, which is a primary intracellular mechanism for degrading aggregated proteins and damaged organelles, plays a crucial role in AD. In this review, we summarize the most recent research progress regarding the process of autophagy and the effect of autophagy on Aβ. We further discuss some typical monomers of natural products that contribute to the clearance of Aβ by autophagy, which can alleviate AD. This provides a new perspective for the application of autophagy modulation in natural product therapy for AD.

Research Progress of Mitophagy in Alzheimer's Disease

The prevalence of Alzheimer's disease (AD) is increasing as the elderly population, which hurts elderly people's cognition and capacity for self-care. The process of mitophagy involves the selective clearance of ageing and impaired mitochondria, which is required to preserve intracellular homeostasis and energy metabolism. Currently, it has been discovered that mitophagy abnormalities are intimately linked to the beginning and progression of AD. This article discusses the mechanism of mitophagy, abnormal mitophagy, and therapeutic effects in AD. The purpose is to offer fresh perspectives on the causes and remedies of AD.

Recent Advances of Mitochondrial Alterations in Alzheimer's Disease: A Perspective of Mitochondrial Basic Events

Alzheimer's disease (AD) is one of the most common neurodegenerative disorders and is characterized by a decrease in learning capacity, memory loss and behavioral changes. In addition to the well-recognized amyloid-β cascade hypothesis and hyperphosphorylated Tau hypothesis, accumulating evidence has led to the proposal of the mitochondrial dysfunction hypothesis as the primary etiology of AD. However, the predominant molecular mechanisms underlying the development and progression of AD have not been fully elucidated. Mitochondrial dysfunction is not only considered an early event in AD pathogenesis but is also involved in the whole course of the disease, with numerous pathophysiological processes, including disordered energy metabolism, Ca2+ homeostasis dysfunction and hyperactive oxidative stress. In the current review, we have integrated emerging evidence to summarize the main mitochondrial alterations- bioenergetic metabolism, mitochondrial inheritance, mitobiogenesis, fission- fusion dynamics, mitochondrial degradation, and mitochondrial movement- underlying AD pathogenesis; precisely identified the mitochondrial regulators; discussed the potential mechanisms and primary processes; highlighted the leading players; and noted additional incidental signaling pathway changes. This review may help to stimulate research exploring mitochondrial metabolically-oriented neuroprotection strategies in AD therapies, leading to a better understanding of the link between the mitochondrial dysfunction hypothesis and AD pathogenesis.

Targeting mitophagy for neurological disorders treatment: advances in drugs and non-drug approaches

Mitochondria serve as a vital energy source for nerve cells. The mitochondrial network also acts as a defense mechanism against external stressors that can threaten the stability of the nervous system. However, excessive accumulation of damaged mitochondria can lead to neuronal death. Mitophagy is an essential pathway in the mitochondrial quality control system and can protect neurons by selectively removing damaged mitochondria. In most neurological disorders, dysfunctional mitochondria are a common feature, and drugs that target mitophagy can improve symptoms. Here, we reviewed the role of mitophagy in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, Huntington's disease, stroke, and traumatic brain injuries. We also summarized drug and non-drug approaches to promote mitophagy and described their therapeutic role in neurological disorders in order to provide valuable insight into the potential therapeutic agents available for neurological disease treatment. However, most studies on mitophagy regulation are based on preclinical research using cell and animal models, which may not accurately reflect the effects in humans. This poses a challenge to the clinical application of drugs targeting mitophagy. Additionally, these drugs may carry the risk of intolerable side effects and toxicity. Future research should focus on the development of safer and more targeted drugs for mitophagy.

Review of PINK1-Parkin-mediated mitochondrial autophagy in Alzheimer's disease

Mitochondrial autophagy plays an important role in maintaining the complexity of mitochondrial functions and removing damaged mitochondria, of which the PINK1-Parkin signal pathway is one of the most classical pathways. Thus, a comprehensive and in-depth interpretation of the PINK1-Parkin signal pathway might deepen our understanding on the impacts of mitochondrial autophagy. Alzheimer's disease (AD) is a classical example of neurodegenerative disease. Research on the pathogenesis and treatments of AD has been a focus of scientific research because of its complexity and the limitations of current drug therapies. It was reported that the pathogenesis of AD might be related to mitochondrial autophagy due to excessive deposition of Aβ protein and aggravation of the phosphorylation of Tau protein. Two key proteins in the PINK1-Parkin signaling pathway, PINK1 and Parkin, have important roles in the folding and accumulation of Aβ protein and the phosphorylation of Tau protein. In addition, the intermediate signal molecules in the PINK1-Parkin signal pathway also have certain effects on AD. In this paper, we first described the role of PINK1-Parkin signal pathway on mitochondrial autophagy, then discussed and analyzed the effect of the PINK1-Parkin signal pathway in AD and other metabolic diseases. Our aim was to provide a theoretical direction to further elucidate the pathogenesis of AD and highlight the key molecules related to AD that could be important targets used for AD drug development.

Comparative analysis of early neurodegeneration signs in a mouse model of Alzheimer's disease-like pathology induced by two types of the central (Intracerebroventricular vs. Intrahippocampal) administration of Aβ25-35 oligomers

Animal models of Alzheimer's disease (AD) induced by intracerebroventricular (ICV) or intrahippocampal (IH) administration of amyloid-beta (Aβ) are widely used in current research. It remains unclear whether these models provide similar outcomes or mimic pathological mechanisms of AD equally. The aim of the work was to compare two models induced by ICV or IH administration of Aβ25-35 oligomers to C57BL/6 mice. Parameters characterizing cognitive function (passive avoidance test), protein expression (IBA1, Aβ, LC3-II) and expression of genes for neuroinflammation (Aif1, Lcn2, Nrf2), autophagy (Atg8, Becn1, Park2), or markers of neurodegeneration (Cst3, Insr, Vegfa) were analyzed. Сognitive deficits, amyloid accumulation, and neuroinflammatory response in the brain evaluated by the microglial activation were similar in both models. Thus, both ways of Aβ administration appear to be equally suitable for modelling AD-like pathology in mice. Our findings strongly support the key role of Aβ load and neuroinflammatory response in the hippocampus and frontal cortex for the progression of AD-like pathology and development of cognitive deficits. There were certain minor differences between the models in the mRNA level of genes involved in the processes of neuroinflammation, neurodegeneration, and autophagy. Modulating effects of the central administration of Aβ25-35 on the mRNA expression of Aif1, Lcn2, Park2, and Vegfa genes in different brain structures were revealed. The effects occurred to be more pronounced with the ICV method compared with the IH method. These findings give insight into the processes at initial stages of Aβ-induced pathology depending on a primary location of Aβ oligomers in the brain.

Maintenance of mitochondrial homeostasis for Alzheimer's disease: Strategies and challenges

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases, and its early onset is closely related to mitochondrial energy metabolism. The brain is only 2% of body weight, but consumes 20% of total energy needs. Mitochondria are responsible for providing energy in cells, and maintaining their homeostasis ensures an adequate supply of energy to the brain. Mitochondrial homeostasis is constituted by mitochondrial quantity and quality control, which is dynamically regulated by mitochondrial energy metabolism, mitochondrial dynamics and mitochondrial quality control. Impaired energy metabolism of brain cells occurs early in AD, and maintaining mitochondrial homeostasis is a promising therapeutic target in the future. We summarized the mechanism of mitochondrial homeostasis in AD, its influence on the pathogenesis of early AD, strategies for maintaining mitochondrial homeostasis, and mitochondrial targeting strategies. This review concludes with the authors' opinions on future research and development for mitochondrial homeostasis of early AD.

Aerobic Exercise Delays Alzheimer's Disease by Regulating Mitochondrial Proteostasis in the Cerebral Cortex and Hippocampus

In clinical practice, Alzheimer's disease (AD), as one of the main neurodegenerative diseases globally, currently has no cure. Recently, the delaying and improving effects of physical exercise on AD have gradually been confirmed; however, the specific mechanism involved needs further clarification. (1) Objective: Explore the mechanism aerobic exercise plays in delaying AD by regulating mitochondrial proteostasis and provide new theoretical bases for improving and delaying AD through aerobic exercise in the future. (2) Methods: Male APP/PS1 mice were randomly divided into a normal group (NG, n = 20), activation group (AG, n = 20), and inhibition group (SG, n = 20). Then, the mice in each group were randomly divided into control group and exercise group (n = 10 mice each), yielding the normal control group (CNG), normal exercise group (ENG), active control group (CAG), active exercise group (EAG), inhibitive control group (CSG), and inhibitive exercise group (ESG). After adaptive training, the mice in the exercise groups were trained on an aerobic treadmill for 12 weeks; we conducted behavioral tests and sampled the results. Then, quantitative real-time PCR (Q-PCR) and Western blot analysis were performed. (3) Results: In the Morris water maze (MWM) test, the latency was significantly reduced and the number of platform crossings was significantly increased in the CAG and ENG compared with the CNG, while the result of the CSG was contrary to this. Compared with the ENG, latency was significantly reduced and the number of platform crossings was significantly increased in the EAG, while the opposite occurred for ESG. Compared with the CAG, the latency was significantly reduced and the number of platform crossings was significantly increased in the EAG, while the results for CSG were contrary. In the step-down test, compared with the CNG, the latency was significantly increased and the number of errors was significantly reduced in the CAG and ENG, respectively, while the results for CSG were contrary. Compared with the ENG, the latency was significantly increased and the number of errors was significantly reduced in the EAG, while the results for ESG were contrary. Compared with the CAG, the latency was significantly increased and the number of errors was significantly reduced in the EAG, while the results for CSG were contrary. Mitochondrial unfolded protein reactions (UPR^mt), mitochondrial autophagy, and mitochondrial protein import levels in each group of mice were detected using Q-PCR and Western blot experiments. Compared with the CNG, the UPR^mt and mitochondrial autophagy levels in the CAG and ENG were significantly increased and the mitochondrial protein import levels were significantly reduced, while the results for the CSG were contrary. Compared with the ENG, the UPR^mt and mitochondrial autophagy levels in the EAG were significantly increased and the mitochondrial protein import levels were significantly reduced, while the results for ESG were contrary. Compared with the CAG, the UPR^mt and mitochondrial autophagy levels in the EAG were significantly increased and the mitochondrial protein import levels were significantly reduced, while the results for CSG were contrary. (4) Conclusions: Aerobic exercise can improve cognitive function levels and delay the symptoms of AD in APP/PS1 mice by regulating mitochondrial proteostasis.

Insights from Drosophila on Aβ- and tau-induced mitochondrial dysfunction: mechanisms and tools

Alzheimer's disease (AD) is the most prevalent neurodegenerative dementia in older adults worldwide. Sadly, there are no disease-modifying therapies available for treatment due to the multifactorial complexity of the disease. AD is pathologically characterized by extracellular deposition of amyloid beta (Aβ) and intracellular neurofibrillary tangles composed of hyperphosphorylated tau. Increasing evidence suggest that Aβ also accumulates intracellularly, which may contribute to the pathological mitochondrial dysfunction observed in AD. According with the mitochondrial cascade hypothesis, mitochondrial dysfunction precedes clinical decline and thus targeting mitochondria may result in new therapeutic strategies. Unfortunately, the precise mechanisms connecting mitochondrial dysfunction with AD are largely unknown. In this review, we will discuss how the fruit fly Drosophila melanogaster is contributing to answer mechanistic questions in the field, from mitochondrial oxidative stress and calcium dysregulation to mitophagy and mitochondrial fusion and fission. In particular, we will highlight specific mitochondrial insults caused by Aβ and tau in transgenic flies and will also discuss a variety of genetic tools and sensors available to study mitochondrial biology in this flexible organism. Areas of opportunity and future directions will be also considered.

The Role of Mitochondrial Dysfunction in Alzheimer's: Molecular Defects and Mitophagy-Enhancing Approaches

Alzheimer's disease (AD), a progressive and chronic neurodegenerative syndrome, is categorized by cognitive and memory damage caused by the aggregations of abnormal proteins, specifically including Tau proteins and β-amyloid in brain tissue. Moreover, mitochondrial dysfunctions are the principal causes of AD, which is associated with mitophagy impairment. Investigations exploring pharmacological therapies alongside AD have explicitly concentrated on molecules accomplished in preventing/abolishing the gatherings of the abovementioned proteins and mitochondria damages. Mitophagy is the removal of dead mitochondria by the autophagy process. Damages in mitophagy, the manner of diversified mitochondrial degeneracy by autophagy resulting in an ongoing aggregation of malfunctioning mitochondria, were also suggested to support AD. Recently, plentiful reports have suggested a link between defective mitophagy and AD. This treaty highlights updated outlines of modern innovations and developments on mitophagy machinery dysfunctions in AD brains. Moreover, therapeutic and nanotherapeutic strategies targeting mitochondrial dysfunction are also presented in this review. Based on the significant role of diminished mitophagy in AD, we suggest that the application of different therapeutic approaches aimed at stimulating mitophagy in AD would be beneficial for targeting or reducing the mitochondrial dysfunction induced by AD.

Mitophagy regulation in aging and neurodegenerative disease

Mitochondria are the primary cellular energy generators, supplying the majority of adenosine triphosphate through oxidative phosphorylation, which is necessary for neuron function and survival. Mitophagy is the metabolic process of eliminating dysfunctional or redundant mitochondria. It is a type of autophagy and it is crucial for maintaining mitochondrial and neuronal health. Impaired mitophagy leads to an accumulation of damaged mitochondria and proteins leading to the dysregulation of mitochondrial quality control processes. Recent research shows the vital role of mitophagy in neurons and the pathogenesis of major neurodegenerative diseases. Mitophagy also plays a major role in the process of aging. This review describes the alterations that are being caused in the mitophagy process at the molecular level in aging and in neurodegenerative diseases, particularly Alzheimer's, Parkinson's, and Huntington's diseases and amyotrophic lateral sclerosis, also looks at how mitophagy can be exploited as a therapeutic target for these diseases.

Berberine Rescues D-Ribose-Induced Alzheimer's Pathology via Promoting Mitophagy

Mitochondrial dysfunction is considered an early event of Alzheimer disease (AD). D-ribose is a natural monosaccharide that exists in cells, especially in mitochondria, and can lead to cognitive dysfunction. However, the reason for this is unclear. Berberine (BBR) is an isoquinoline alkaloid that can target mitochondria and has great prospect in the treatment of AD. The methylation of PINK1 reinforces the burden of Alzheimer's pathology. This study explores the role of BBR and D-ribose in the mitophagy and cognitive function of AD related to DNA methylation. APP/PS1 mice and N2a cells were treated with D-ribose, BBR, and mitophagy inhibitor Mdivi-1 to observe their effects on mitochondrial morphology, mitophagy, neuron histology, AD pathology, animal behavior, and PINK1 methylation. The results showed that D-ribose induced mitochondrial dysfunction, mitophagy damage, and cognitive impairment. However, BBR inhibition of PINK1 promoter methylation can reverse the above effects caused by D-ribose, improve mitochondrial function, and restore mitophagy through the PINK1-Parkin pathway, thus reducing cognitive deficits and the burden of AD pathology. This experiment puts a new light on the mechanism of action of D-ribose in cognitive impairment and reveals new insights in the use of BBR for AD treatment.

Focus on Alzheimer's Disease: The Role of Fibroblast Growth Factor 21 and Autophagy

Alzheimer's disease (AD) is a disorder of the central nervous system that is typically marked by progressive cognitive impairment and memory loss. Amyloid β plaque deposition and neurofibrillary tangles with hyperphosphorylated tau are the two hallmark pathologies of AD. In mammalian cells, autophagy clears aberrant protein aggregates, thus maintaining proteostasis as well as neuronal health. Autophagy affects production and metabolism of amyloid β and accumulation of phosphorylated tau proteins, whose malfunction can lead to the progression of AD. On the other hand, defective autophagy has been found to induce the production of the neuroprotective factor fibroblast growth factor 21 (FGF21), although the underlying mechanism is unclear. In this review, we highlight the significance of aberrant autophagy in the pathogenesis of AD, discuss the possible mechanisms by which defective autophagy induces FGF21 production, and analyze the potential of FGF21 in the treatment of AD. The findings provide some insights into the potential role of FGF21 and autophagy in the pathogenesis of AD.

PINK1/Parkin-mediated mitophagy in neurodegenerative diseases

Mitochondria play key roles in bioenergetics, metabolism, and signaling; therefore, stable mitochondrial function is essential for cell survival, particularly in energy-intensive neuronal cells. In neurodegenerative diseases, damaged mitochondria accumulate in neurons causing associated bioenergetics deficiency, impaired cell signaling, defective cytoplasmic calcium buffering, and other pathological changes. Mitochondrial quality control is an important mechanism to ensure the maintenance of mitochondrial health, homeostasis, and mitophagy, the latter of which is a pathway that delivers defective mitochondria to the lysosome for degradation. Defective mitophagy is thought to be responsible for the accumulation of damaged mitochondria, which leads to cellular dysfunction and/or death in neurodegenerative diseases. PINK1/Parkin mainly regulates ubiquitin-dependent mitophagy, which is crucial for many aspects of mitochondrial physiology, particularly the initiation of autophagic mechanisms. Therefore, in the present review, we summarize the current knowledge of the conventional mitophagy pathway, focusing on the molecular mechanisms underlying mitophagy dysregulation in prion disease and other age-related neurodegenerative diseases, especially in relation to the PINK1/Parkin pathway. Moreover, we list the inducers of mitophagy that possess neuroprotective effects, in addition to their mechanisms related to the PINK1/Parkin pathway. These mechanisms may provide potential interventions centered on the regulation of mitophagy and offer therapeutic strategies for the treatment of neurodegenerative diseases.

Mitophagy in Alzheimer's disease: Molecular defects and therapeutic approaches

Mitochondrial dysfunctions are central players in Alzheimer's disease (AD). In addition, impairments in mitophagy, the process of selective mitochondrial degradation by autophagy leading to a gradual accumulation of defective mitochondria, have also been reported to occur in AD. We provide an updated overview of the recent discoveries and advancements on mitophagic molecular dysfunctions in AD-derived fluids and cells as well as in AD brains. We discuss studies using AD cellular and animal models that have unraveled the contribution of relevant AD-related proteins (Tau, Aβ, APP-derived fragments and APOE) in mitophagy failure. In accordance with the important role of impaired mitophagy in AD, we report on various therapeutic strategies aiming at stimulating mitophagy in AD and we summarize the benefits of these potential therapeutic strategies in human clinical trials.

Research progress in traditional Chinese medicine in the treatment of Alzheimer's disease and related dementias

Alzheimer's disease (AD) is the world's leading cause of dementia and has become a huge economic burden on nations and families. However, the exact etiology of AD is still unknown, and there are no efficient medicines or methods to prevent the deterioration of cognition. Traditional Chinese medicine (TCM) has made important contributions in the battle against AD based on the characteristics of multiple targets of TCM. This study reviewed the treatment strategies and new discoveries of traditional Chinese medicine in current research, which may be beneficial to new drug researchers.

Coenzyme Q10 ameliorates aging-induced memory deficits via modulation of apoptosis, oxidative stress, and mitophagy in aged rats

The behavioral effects and molecular signaling mechanisms of Coenzyme Q₁₀ (Q₁₀) in age-related memory impairment are poorly understood. This study aimed to investigate the effects of Q₁₀ on memory impairment, oxidative stress, apoptosis, and mitophagy in aged rats. 40 aged (24 months old) and 10 young (3 months old) male Wistar rats were randomly divided into the following groups (n = 10/group): young + vehicle, aged + vehicle, and aged + Q₁₀ (at 100, 200, 300 mg/kg/day doses). Treatments were administrated orally by gavage for 2 weeks. The novel object recognition test was used to assess episodic memory. Oxidative stress, apoptosis, and mitophagy-related protein expressions were measured in the hippocampus. We found that Q10 reversed aging-induced memory impairment at the dose of 300 mg/kg. Moreover, aging was associated with a reduction in ATP production, decrease in mitophagy-related proteins (PINK, Parkin, and P62 levels and LC3II/I ratio), excessive generation of reactive oxygen species and lipid peroxidation, and apoptosis in the hippocampus, which were partially reversed following oral administration of Q₁₀. These findings indicate the therapeutic potential of Q₁₀ in aging-induced memory decline.

MCU knockdown in hippocampal neurons improves memory performance of an Alzheimer's disease mouse model

Alzheimer's disease (AD) is a progressive and degenerative disorder accompanied by cognitive decline, which could be promoted by mitochondrial dysfunction induced by mitochondrial Ca ²⁺ (mCa ²⁺) homeostasis Mitochondrial calcium uniporter (MCU), a key channel of mCa ²⁺ uptake, may be a target for AD treatment. In the present study, we reveal for the first time that MCU knockdown in hippocampal neurons improves the memory performance of APP/PS1/tau mice through radial arm maze task. Western blot analysis, transmission electron microscopy (TEM), Golgi staining, immunohistochemistry (IHC) and ELISA results demonstrate that MCU knockdown in hippocampal neurons upregulates the levels of postsynaptic density protein 95 (PSD95) and synaptophysin (SYP), and increases the numbers of synapses and dendritic spines. Meanwhile, MCU knockdown in hippocampal neurons decreases the neuroinflammatory response induced by astrogliosis and high levels of IL-1β and TNF-α, and improves the PINK1-Parkin mitophagy signaling pathway and increases the level of Beclin-1 but decreases the level of P62. In addition, MCU knockdown in hippocampal neurons recovers the average volume and number of mitochondria. These data confirm that MCU knockdown in hippocampal neurons improves the memory performance of APP/PS1/tau mice through ameliorating the synapse structure and function, relieving the inflammation response and recovering mitophagy, indicating that MCU inhibition has the potential to be developed as a novel therapy for AD.

Medicinal Herbs and Their Derived Ingredients Protect against Cognitive Decline in In Vivo Models of Alzheimer’s Disease

Alzheimer’s disease (AD) has pathological hallmarks including amyloid beta (Aβ) plaque formation. Currently approved single-target drugs cannot effectively ameliorate AD. Medicinal herbs and their derived ingredients (MHDIs) have multitarget and multichannel properties, engendering exceptional AD treatment outcomes. This review delineates how in in vivo models MHDIs suppress Aβ deposition by downregulating β- and γ-secretase activities; inhibit oxidative stress by enhancing the antioxidant activities and reducing lipid peroxidation; prevent tau hyperphosphorylation by upregulating protein phosphatase 2A expression and downregulating glycogen synthase kinase-3β expression; reduce inflammatory mediators partly by upregulating brain-derived neurotrophic factor/extracellular signal-regulated protein kinase 1/2-mediated signaling and downregulating p38 mitogen-activated protein kinase (p38 MAPK)/c-Jun N-terminal kinase (JNK)-mediated signaling; attenuate synaptic dysfunction by increasing presynaptic protein, postsynaptic protein, and acetylcholine levels and preventing acetylcholinesterase activity; and protect against neuronal apoptosis mainly by upregulating Akt/cyclic AMP response element-binding protein/B-cell lymphoma 2 (Bcl-2)-mediated anti-apoptotic signaling and downregulating p38 MAPK/JNK/Bcl-2-associated x protein (Bax)/caspase-3-, Bax/apoptosis-inducing factor-, C/EBP homologous protein/glucose-regulated protein 78-, and autophagy-mediated apoptotic signaling. Therefore, MHDIs listed in this review protect against Aβ-induced cognitive decline by inhibiting Aβ accumulation, oxidative stress, tau hyperphosphorylation, inflammation, synaptic damage, and neuronal apoptosis in the cortex and hippocampus during the early and late AD phases.

Preclinical evidence and possible mechanisms of β-asarone for rats and mice with Alzheimer’s disease: A systematic review and meta-analysis

Background: Currently, there are many different drugs to improve Alzheimer’s disease (AD) from different pathways. As a supplement and alternative medicine, traditional Chinese medicine (TCM) targets multiple pathways which may be different from classical Western medicine, which may be orchestrated with Western medicine to materialize multiplying efficacy in AD patients.

Objective: To investigate the therapeutic effect and assess the available preclinical evidence and possible mechanisms of β-asarone which was extracted from Acorus gramineus Soland (Araceae, AGS) for AD based on rat and mouse animal models.

Methods: PubMed, Embase, Scopus, Cochrane Library, BIOSIS Previews, Web of Science, EBSCO, and Google Scholar were searched from inception to 5 May 2022. Rat and mouse experiments assessing the therapeutic effects of β-asarone for AD were included. Primary outcomes were neuroethology, including escape latency and times of crossing platform. Second outcomes were cell apoptosis, including Bax and Bcl-2. The weighted mean difference (WMD) was generated for continuous variables. The relative outcomes were analyzed with the aid of Get Data Graph Digitizer 2.26 and software STATA version 16.0 MP.

Results: For the primary endpoint, compared with the modeling group, β-asarone significantly decreased the escape latency (WMD = -12.61, 95% CI: -18.66 to -6.57) and increased the times of crossing platform (WMD = 1.50, 95% CI: 0.31–2.70). For the secondary endpoint, β-asarone remarkably reduced the relative expression of the amyloid precursor protein (APP) (WMD = −2.25, 95% CI: −2.49 to −2.01), decreased the expression of the apoptosis-related protein, associated X protein (Bax) (WMD = −2.40, 95% CI: −3.51 to −1.29), lowered the expression of apoptosis-related protein, B-cell lymphoma-2 (Bcl-2) (WMD = 0.42, 95% CI: 0.38–0.46), and decreased the signal pathway-related proteins, phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) (WMD = −0.70, 95% CI: −0.93 to −0.47) over the control group.

Conclusion: β-asarone spectacularly improved the learning ability and memory in rats and mice, which might be correlated with its potential neuroprotective effect through multiple signaling pathways.

Hub Genes, Diagnostic Model, and Predicted Drugs Related to Iron Metabolism in Alzheimer's Disease

Alzheimer's disease (AD), the most common neurodegenerative disease, remains unclear in terms of its underlying causative genes and effective therapeutic approaches. Meanwhile, abnormalities in iron metabolism have been demonstrated in patients and mouse models with AD. Therefore, this study sought to find hub genes based on iron metabolism that can influence the diagnosis and treatment of AD. First, gene expression profiles were downloaded from the GEO database, including non-demented (ND) controls and AD samples. Fourteen iron metabolism-related gene sets were downloaded from the MSigDB database, yielding 520 iron metabolism-related genes. The final nine hub genes associated with iron metabolism and AD were obtained by differential analysis and WGCNA in brain tissue samples from GSE132903. GO analysis revealed that these genes were mainly involved in two major biological processes, autophagy and iron metabolism. Through stepwise regression and logistic regression analyses, we selected four of these genes to construct a diagnostic model of AD. The model was validated in blood samples from GSE63061 and GSE85426, and the AUC values showed that the model had a relatively good diagnostic performance. In addition, the immune cell infiltration of the samples and the correlation of different immune factors with these hub genes were further explored. The results suggested that these genes may also play an important role in immunity to AD. Finally, eight drugs targeting these nine hub genes were retrieved from the DrugBank database, some of which were shown to be useful for the treatment of AD or other concomitant conditions, such as insomnia and agitation. In conclusion, this model is expected to guide the diagnosis of patients with AD by detecting the expression of several genes in the blood. These hub genes may also assist in understanding the development and drug treatment of AD.

A Review of ApoE4 Interference Targeting Mitophagy Molecular Pathways for Alzheimer's Disease

Alzheimer's disease (AD) is one of the major worldwide causes of dementia that is characterized by irreversible decline in learning, memory loss, and behavioral impairments. Mitophagy is selective autophagy through the clearance of aberrant mitochondria, specifically for degradation to maintain energy generation and neuronal and synaptic function in the brain. Accumulating evidence shows that defective mitophagy is believed to be as one of the early and prominent features in AD pathogenesis and has drawn attention in the recent few years. APOE ε4 allele is the greatest genetic determinant for AD and is widely reported to mediate detrimental effects on mitochondria function and mitophagic process. Given the continuity of the physiological process, this review takes the mitochondrial dynamic and mitophagic core events into consideration, which highlights the current knowledge about the molecular alterations from an APOE-genotype perspective, synthesizes ApoE4-associated regulations, and the cross-talk between these signaling, along with the focuses on general autophagic process and several pivotal processes of mitophagy, including mitochondrial dynamic (DRP1, MFN-1), mitophagic induction (PINK1, Parkin). These may shed new light on the link between ApoE4 and AD and provide novel insights for promising mitophagy-targeted therapeutic strategies for AD.

Biologically Active Compounds Present in Tobacco Smoke: Potential Interactions Between Smoking and Mental Health

Tobacco dependence remains one of the major preventable causes of premature morbidity and mortality worldwide. There are well over 8,000 compounds present in tobacco and tobacco smoke, but we do not know what effect, if any, many of them have on smokers. Major interest has been on nicotine, as well as on toxic and carcinogenic effects and several major and minor components of tobacco smoke responsible for the negative health effects of smoking have been elucidated. Smokers themselves report a variety of positive effects from smoking, including effects on depression, anxiety and mental acuity. Smoking has also been shown to have protective effects in Parkinson’s Disease. Are the subjective reports of a positive effect of smoking due to nicotine, of some other components of tobacco smoke, or are they a manifestation of the relief from nicotine withdrawal symptoms that smoking provides? This mini-review summarises what is currently known about the components of tobacco smoke with potential to have positive effects on smokers.

Parkin as a Molecular Bridge Linking Alzheimer’s and Parkinson’s Diseases?

Alzheimer’s (AD) and Parkinson’s (PD) diseases are two distinct age-related pathologies that are characterized by various common dysfunctions. They are referred to as proteinopathies characterized by ubiquitinated protein accumulation and aggregation. This accumulation is mainly due to altered lysosomal and proteasomal clearing processes and is generally accompanied by ER stress disturbance, autophagic and mitophagic defects, mitochondrial structure and function alterations and enhanced neuronal cell death. Genetic approaches aimed at identifying molecular triggers responsible for familial forms of AD or PD have helped to understand the etiology of their sporadic counterparts. It appears that several proteins thought to contribute to one of these pathologies are also likely to contribute to the other. One such protein is parkin (PK). Here, we will briefly describe anatomical lesions and genetic advances linked to AD and PD as well as the main cellular processes commonly affected in these pathologies. Further, we will focus on current studies suggesting that PK could well participate in AD and thereby act as a molecular bridge between these two pathologies. In particular, we will focus on the transcription factor function of PK and its newly described transcriptional targets that are directly related to AD- and PD-linked cellular defects.

Explore the Mechanism of β-Asarone on Improving Cognitive Dysfunction in Rats with Diabetic Encephalopathy

Background: The number of people with diabetes is increasing, and many patients have significantly impaired cognitive function. For patients with diabetic encephalopathy (DE), simply lowering blood sugar does not improve learning and memory. Studies have shown that β-asarone can significantly improve cognitive impairment in patients with DE, but the specific mechanism of action is unclear. Objective: This experiment hopes to use a variety of experimental methods to clarify the protective effect and mechanism of β-asarone on brain neurons during the development of DE disease. Methods: A high-sugar and high-fat diet and streptozotocin injection-induced DE rat model was used. β-asarone was administered for four weeks. The experiment used the Morris water maze test, biochemical index detection, and many methods to evaluate the neuroprotective effect of β-asarone on DE rats from various aspects and understand its mechanism. Results: β-asarone reduced neuronal cell damage and significantly improved the learning and memory ability of DE rats. In addition, β-asarone can reduce the oxidative stress response and amyloid-β accumulation in the brain of DE model rats and increase the content of brain-derived neurotrophic factor (BDNF) in the brain tissue, thereby reducing neuronal cell apoptosis and playing a protective role. Conclusion: β-asarone can reduce the accumulation of oxidative stress and amyloid-β in the brain, increase the content of BDNF, reduce the apoptosis of neuronal cells, and exert neuronal protection, thereby improving the learning and memory ability of DE model rats.

PINK1 Alleviates Cognitive Impairments via Attenuating Pathological Tau Aggregation in a Mouse Model of Tauopathy

As a primary cause of dementia and death in older people, Alzheimer’s disease (AD) has become a common problem and challenge worldwide. Abnormal accumulation of tau proteins in the brain is a hallmark pathology of AD and is closely related to the clinical progression and severity of cognitive deficits. Here, we found that overexpression of phosphatase and tensin homolog (PTEN)-induced kinase 1 (PINK1) effectively promoted the degradation of tau, thereby rescuing neuron loss, synaptic damage, and cognitive impairments in a mouse model of tauopathy with AAV-full-length human Tau (hTau) injected into the hippocampal CA1 area (hTau mice). Overexpression of PINK1 activated autophagy, and chloroquine but not MG132 reversed the PINK1-induced decrease in human Tau levels and cognitive improvement in hTau mice. Furthermore, PINK1 also ameliorated mitochondrial dysfunction induced by hTau. Taken together, our data revealed that PINK1 overexpression promoted degradation of abnormal accumulated tau via the autophagy–lysosome pathway, indicating that PINK1 may be a potential target for AD treatment.

Pharmacological modulation of autophagy for Alzheimer’s disease therapy: Opportunities and obstacles

Alzheimer's disease (AD) is a prevalent and deleterious neurodegenerative disorder characterized by an irreversible and progressive impairment of cognitive abilities as well as the formation of amyloid β (Aβ) plaques and neurofibrillary tangles (NFTs) in the brain. By far, the precise mechanisms of AD are not fully understood and no interventions are available to effectively slow down progression of the disease. Autophagy is a conserved degradation pathway that is crucial to maintain cellular homeostasis by targeting damaged organelles, pathogens, and disease-prone protein aggregates to lysosome for degradation. Emerging evidence suggests dysfunctional autophagy clearance pathway as a potential cellular mechanism underlying the pathogenesis of AD in affected neurons. Here we summarize the current evidence for autophagy dysfunction in the pathophysiology of AD and discuss the role of autophagy in the regulation of AD-related protein degradation and neuroinflammation in neurons and glial cells. Finally, we review the autophagy modulators reported in the treatment of AD models and discuss the obstacles and opportunities for potential clinical application of the novel autophagy activators for AD therapy.

Neuroprotective Effect of Danggui Shaoyao San via the Mitophagy-Apoptosis Pathway in a Rat Model of Alzheimer's Disease

Alzheimer's disease (AD) is a serious neurodegenerative disease. While the main pathological characteristic of AD is widely believed to be the accumulation of amyloid-beta (Aβ) in neurons around neurofibrillary plaques, the molecular mechanism of pathological changes is not clear. Traditional Chinese medicine offers many treatments for AD. Among these, Danggui Shaoyao San (DSS) is a classic prescription. In this study, an AD model was established by injecting Aβ 1-42 into the brains of rats, which were then treated with different concentrations of Danggui Shaoyao San (sham operation; model; and Danggui Shaoyao San high-dose, medium-dose, and low-dose intervention groups). The Morris water maze test was used to assess the learning and memory abilities of the animals in each group. Nissl staining was used to detect neurons. Mitophagy was evaluated by transmission electron microscopy and immunofluorescence colocalization. Apoptosis was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. The expression levels of autophagy- and apoptosis-related proteins were measured by western blot. Compared to the model group, the groups of AD rats administered medium and high doses of Danggui Shaoyao San showed significantly increased learning and memory abilities (P < 0.05), as well as significantly increased autophagosomes in the hippocampus. Moreover, the expression of PTEN-induced kinase 1 (PINK1), Parkin, and microtubule-associated protein light chain 3 (LC3-I/LC3-II) was increased, while that of p62 was significantly decreased (P < 0.05). The neuronal apoptosis rate was also significantly decreased, the Bcl-2/Bax ratio was significantly increased, and the cleaved caspase-3 protein expression was significantly decreased (P < 0.05). Therefore, Danggui Shaoyao San inhibited neuronal apoptosis in AD rats via a mechanism that may be related to the activation of the PINK1-Parkin-mediated mitophagy signaling pathway.

Insights Into Parkin-Mediated Mitophagy in Alzheimer's Disease: A Systematic Review

Background: Parkin-mediated mitophagy is the dominant mitophagy pathway of neural cells. Its restoration will result in prevention of cognitive decline, including Alzheimer's disease (AD). The role of this mitophagy pathway in neurodegenerative diseases has drawn attention in recent years. The two main pathological proteins in AD, amyloid β (Aβ) and human Tau (hTau), interfere with mitochondrial dynamics through several pathways. However, taking into consideration the specific interactions between Aβ/hTau and Parkin, special focus is required on this mitophagy pathway and AD. In this review, these interactions are fully discussed, and an overview of the neuroprotective drugs that enhance Parkin-mediated mitophagy is presented. Methods: This systematic review was performed according to PRISMA guidelines, and a comprehensive literature search was done in the electronic databases up to September 2020, using search terms in the titles and abstracts to identify relevant studies. One hundred eighty-six articles were found, and 113 articles were screened by title and abstract. Finally, 25 articles were included in this systematic review according to our inclusion and exclusion criteria. Results: Accumulation of Aβ and hTau affects mitophagy, including Parkin-mediated. Tau seems to prevent Parkin translocation directly. A Parkin level in the cell appears to be of importance in determining the damage caused by Aβ and hTau and in the future therapeutic approaches. Parkin controls the PINK1 level via the presenillins, suggesting that mutations in presenillins affect Parkin mitophagy. Significance: Parkin mitophagy is a process affected by several AD pathological events multidimensionally.

Mitophagy Regulates Neurodegenerative Diseases

Mitochondria play an essential role in supplying energy for the health and survival of neurons. Mitophagy is a metabolic process that removes dysfunctional or redundant mitochondria. This process preserves mitochondrial health. However, defective mitophagy triggers the accumulation of damaged mitochondria, causing major neurodegenerative disorders. This review introduces molecular mechanisms and signaling pathways behind mitophagy regulation. Furthermore, we focus on the recent advances in understanding the potential role of mitophagy in the pathogenesis of major neurodegenerative diseases (Parkinson's, Alzheimer's, Huntington's, etc.) and aging. The findings will help identify the potential interventions of mitophagy regulation and treatment strategies of neurodegenerative diseases.

Cardiac senescence is alleviated by the natural flavone acacetin via enhancing mitophagy

Cardiac senescence is associated with cardiomyopathy which is a degenerative disease in the aging process of the elderly. The present study investigates using multiple experimental approaches whether the natural flavone acacetin could attenuate myocardial senescence in C57/BL6 mice and H9C2 rat cardiac cells induced by D-galactose. We found that the impaired heart function in D-galactose-induced accelerated aging mice was improved by oral acacetin treatment in a dose-dependent manner. Acacetin significantly countered the increased serum advanced glycation end products, the myocardial telomere length shortening, the increased cellular senescence marker proteins p21 and p53, and the reduced mitophagy signaling proteins PINK1/Parkin and Sirt6 expression in aging mice. In H9C2 rat cardiac cells, acacetin alleviated cell senescence induced by D-galactose in a concentration-dependent manner. Acacetin decreased p21 and p53 expression, up-regulated PINK1/Parkin, LC3II/LC3I ratio, pLKB1, pAMPK and Sirt6, and reversed the depolarized mitochondrial membrane potential in aging cardiac cells. Mitophagy inhibition with 3-methyladenine or silencing Sirt6 abolished the protective effects of acacetin against cardiac senescence. Further analysis revealed that acacetin effect on Sirt6 was mediated by Sirt1 activation and increase of NAD+/NADH ratio. These results demonstrate that acacetin significantly inhibits in vivo and in vitro cardiac senescence induced by D-galactose via Sirt1-mediated activation of Sirt6/AMPK signaling pathway, thereby enhancing mitophagy and preserving mitochondrial function, which suggests that acacetin may be a drug candidate for treating cardiovascular disorders related to aging.

LncRNA NEAT1 accelerates renal tubular epithelial cell damage by modulating mitophagy via miR-150-5p-DRP1 axis in diabetic nephropathy

NEW FINDINGS

What is the central question of this study? Diabetic nephropathy (DN) is a severe complication of diabetes correlated with a higher mortality rate in diabetic patients. Renal tubular injury participates in the pathogenesis of DN. We aimed to uncover the biological function of the NEAT1-miR-150-5p-DRP1 axis in an in vitro model of DN and elaborate the potential mechanisms. What is the main finding and its importance? NEAT1 facilitated high glucose-induced damage in HK-2 cells by reducing mitophagy via the miR-150-5p-DRP1 axis, which sheds light on DN pathogenesis and reveals a potential treatment for DN.

ABSTRACT

Diabetic nephropathy (DN) is a severe complication in diabetic patients, with a high mortality rate. Renal tubular injury is involved in the pathogenesis of DN. In this study, we aimed to uncover the regulatory roles of the NEAT1-miR-150-5p-DRP1 axis in an in vitro model of DN and its possible mechanisms. High glucose-challenged HK-2 cells were used as an in vitro DN model. NEAT1, miR-150-5p and DRP1 levels were assessed by RT-qPCR. Cell viability was determined by the MTT assay. MitoSOX Red and JC-1 were used to evaluate intracellular production of reactive oxygen species and mitochondrial membrane potential, respectively. Lactate dehydrogenase release and superoxide dismutase activity were assessed with commercial kits. The protein levels of DRP1, p62, BECN1(beclin 1) and BNIP3 were determined by western blotting. The interaction between NEAT1 (DRP1) and miR-150-5p was verified by a dual-luciferase reporter assay and an RNA immunoprecipitation assay. Our results showed that in response to high glucose the NEAT1 and DRP1 levels were upregulated, whereas the miR-150-5p level was downregulated in HK-2 cells. Knockdown of NEAT1 or DRP1 in high glucose-challenged HK-2 cells inhibited excessive reactive oxygen species production and lactate dehydrogenase release, increased cell viability, mitochondrial membrane potential and superoxide dismutase activity and enhanced mitophagy. Inhibition of miR-150-5p resulted in the opposite results. Mechanistically, NEAT1 sponged miR-150-5p to increase the DRP1 level. Moreover, silencing of NEAT1 or DRP1 could counteract miR-150-5p inhibition-induced deleterious effects. Collectively, our findings indicate that NEAT1 facilitates high glucose-induced damage in HK-2 cells by suppressing mitophagy via the miR-150-5p-DRP 1 axis, which sheds light on a novel mechanism of DN.

Mitochondrial Dynamics: A Key Role in Neurodegeneration and a Potential Target for Neurodegenerative Disease

In neurodegenerative diseases, neurodegeneration has been related to several mitochondrial dynamics imbalances such as excessive fragmentation of mitochondria, impaired mitophagy, and blocked mitochondria mitochondrial transport in axons. Mitochondria are dynamic organelles, and essential for energy conversion, neuron survival, and cell death. As mitochondrial dynamics have a significant influence on homeostasis, in this review, we mainly discuss the role of mitochondrial dynamics in several neurodegenerative diseases. There is evidence that several mitochondrial dynamics-associated proteins, as well as related pathways, have roles in the pathological process of neurodegenerative diseases with an impact on mitochondrial functions and metabolism. However, specific pathological mechanisms need to be better understood in order to propose new therapeutic strategies targeting mitochondrial dynamics that have shown promise in recent studies.

Potential benefits of phytochemicals from Azadirachta indica against neurological disorders

Azadirachta indica or Neem has been extensively used in the Indian traditional medical system because of its broad range of medicinal properties. Neem contains many chemically diverse and structurally complex phytochemicals such as limonoids, flavonoids, phenols, catechins, gallic acid, polyphenols, nimbins. These phytochemicals possess vast array of therapeutic activities that include anti-feedant, anti-viral, anti-malarial, anti-bacterial, anti-cancer properties. In recent years, many phytochemicals from Neem have been shown to be beneficial against various neurological disorders like Alzheimer's and Parkinson's disease, mood disorders, ischemic-reperfusion injury. The neuroprotective effects of the phytochemicals from Neem are primarily mediated by their anti-oxidant, anti-inflammatory and anti-apoptotic activities along with their ability to modulate signaling pathways. However, extensive studies are still required to fully understand the molecular mechanisms involved in neuropotective effects of phytochemicals from Neem. This review is an attempt to cover the neuroprotective properties of various phytochemicals from Neem along with their mechanism of action so that the potential of the compounds could be realized to reduce the burden of neurodegenerative diseases.