SIRT1 Protects Dopaminergic Neurons in Parkinson's Disease Models via PGC-1α-Mediated Mitochondrial Biogenesis

SIRT1: a potential therapeutic target for coronary heart disease combined with anxiety or depression

Coronary heart disease (CHD) combined with anxiety or depression is increasingly receiving attention in the clinical field of cardiology, and exploring the comorbidity pathological mechanisms of cardiovascular disease combined with psychological disorders is a hot research topic for scholars in this field. Current research suggests that Silent Information Regulatory Factor 1 (SIRT1) may serve as a potential biomarker for the comorbidity mechanism and treatment of CHD with anxiety or depression. SIRT1 is considered a promising therapeutic target for CHD combined with anxiety or depression, with the ability to regulate inflammatory cytokine levels, alleviate oxidative stress damage, activate multiple signalling pathways, reduce platelet hyperresponsiveness, and exert neuroprotective and cardioprotective effects. In this comprehensive review, we deeply studied the structure, function, and mechanism of SIRT1, and discussed its protective effects in the cardiovascular and nervous system. The latest progress in the mechanism of SIRT1's role in CHD combined with anxiety or depression was emphasised, including its specific mechanisms in regulating inflammatory response, alleviating oxidative stress, and mediating various signalling pathways. In addition, this article also summarises the therapeutic potential of SIRT1 as a potential biomarker in patients with CHD combined with anxiety or depression.

Silent Information Regulator 1/Peroxisome Proliferator-Activated Receptor-γ Coactivator-1α Axis: A Promising Target for Parkinson's and Alzheimer's Disease Therapies

One of the key challenges in medical research is developing safe medications to treat neurodegenerative disorders. Increased oxidative stress, mitochondrial dysfunction, and neuroinflammation are common features of Alzheimer's disease (AD) and Parkinson's disease (PD). Silent information regulator 1 (SIRT-1), part of the sirtuin family, plays a critical role in various physiological processes by binding to histones and nonhistone proteins. SIRT-1 primarily mitigates oxidative stress and regulates mitochondrial activity by maintaining the deacetylated form of peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), ensuring stable PGC-1α levels. Research has shown reduced SIRT-1/PGC-1α expression in AD and PD models. Targeting this pathway presents a promising therapeutic approach for managing AD and PD, potentially leading to disease-modifying treatments and improved outcomes. This review highlights the findings of various studies suggesting that the SIRT-1/PGC-1α pathway promotes mitochondrial biogenesis, synaptic plasticity, and cognitive function, as well as exerts antioxidant, anti-inflammatory, and anti-apoptotic effects, offering a potential method for AD and PD treatment.

Atractylenolide-I Ameliorates Motor Deficits and Reduces Inflammation of the Spinal Cord by SIRT1/PGC-1α Pathway in MPTP Subacute Mouse Model of Parkinson's Disease

Background

Parkinson's disease (PD) is a neurodegenerative movement disorder that impacts various systems, including the substantia nigra (SN) par compacta (SNpc) and extranigral regions like the spinal cord. The presence of persistent inflammation in the SN and spinal cord is associated with movement difficulties in PD. Atractylenolide-I (ATR-I) is a natural sesquiterpene recognized for its anti-inflammatory and neuroprotective effects. This research aimed to assess the impact of ATR-I treatment on motor function and inflammation in MPTP-induced subacute PD mice, particularly focusing on the role of ATR-I in spinal cord inflammation.

Methods

The motor functions of the mice were assessed using suspension and gait tests. Dopaminergic neuronal loss in the SNpc and microglial activation in both the SNpc and spinal cord were evaluated through immunofluorescence staining. The levels of inflammatory mediators in the spinal cord were measured using RT-qPCR analysis. The expressions of SIRT1 and PGC-1α in the spinal cord were analyzed through Western blotting and RT-qPCR.

Results

ATR-I treatment improved motor deficits in MPTP-induced mice. Moreover, ATR-I reduced the loss of dopamine neurons and microglial activation in the SNpc of MPTP-induced mice. Additionally, ATR-I suppressed spinal cord inflammation by decreasing microglial activation and the mRNA expression of TNF-α, IL-1β, and iNOS in MPTP-induced mice. Interestingly, ATR-I also upregulated SIRT1 and PGC-1α levels in the spinal cord of MPTP-induced mice.

Conclusion

These findings suggest that ATR-I exhibits anti-inflammatory and neuroprotective properties in PD. The attenuation of spinal cord inflammation via the SIRT1/PGC-1α pathway may contribute to enhancing motor function, highlighting ATR-I as a potential therapeutic avenue for PD.

Tetramethylpyrazine nitrone exerts neuroprotection via activation of PGC-1α/Nrf2 pathway in Parkinson's disease models

INTRODUCTION

Parkinson's disease (PD) is common neurodegenerative disease where oxidative stress and mitochondrial dysfunction play important roles in its progression. Tetramethylpyrazine nitrone (TBN), a potent free radical scavenger, has shown protective effects in various neurological conditions. However, the neuroprotective mechanisms of TBN in PD models remain unclear.

OBJECTIVES

We aimed to investigate TBN's neuroprotective effects and mechanisms in PD models.

METHODS

TBN's neuroprotection was initially measured in MPP+/MPTP-induced PD models. Subsequently, a luciferase reporter assay was used to detect peroxisome proliferator-activated receptor γ co-activator 1α (PGC-1α) promoter activity. Effects of TBN on antioxidant damage and the PGC-1α/Nuclear factor erythroid-2-related factor 2 (Nrf2) pathway were thoroughly investigated.

RESULTS

In MPP+-induced cell model, TBN (30-300 μM) increased cell survival by 9.95 % (P < 0.05), 16.63 % (P < 0.001), and 24.09 % (P < 0.001), respectively. TBN enhanced oxidative phosphorylation (P < 0.05) and restored PGC-1α transcriptional activity suppressed by MPP+ (84.30 % vs 59.03 %, P < 0.01). In MPTP-treated mice, TBN (30 mg/kg) ameliorated motor impairment, increased striatal dopamine levels (16.75 %, P < 0.001), dopaminergic neurons survival (27.12 %, P < 0.001), and tyrosine hydroxylase expression (28.07 %, P < 0.01). Selegiline, a positive control, increased dopamine levels (15.35 %, P < 0.001) and dopaminergic neurons survival (25.34 %, P < 0.001). Additionally, TBN reduced oxidative products and activated the PGC-1α/Nrf2 pathway. PGC-1α knockdown diminished TBN's neuroprotective effects, decreasing cell viability from 73.65 % to 56.87 % (P < 0.001).

CONCLUSION

TBN has demonstrated consistent effectiveness in MPP+-induced midbrain neurons and MPTP-induced mice. Notably, the therapeutic effect of TBN in mitigating motor deficits and neurodegeneration is superior to selegiline. The neuroprotective mechanisms of TBN are associated with activation of the PGC-1α/Nrf2 pathway, thereby reducing oxidative stress and maintaining mitochondrial function. These findings suggest that TBN may be a promising therapeutic candidate for PD, warranting further development and investigation.

Decoding the Role of Nuclear Sirtuins in Parkinson's Pathogenesis

Parkinson's disease (PD) is the second most prevailing degenerative disease that deals with dopaminergic neuronal loss and deficiency of dopamine in SNpc and striatum. Manifestations primarily include motor symptoms like tremor, rigidity, and akinesia/dyskinesia along with some nonmotor symptoms like GI and olfactory dysfunction. α-Synuclein pathogenesis is the major cause behind progression of PD; however there are many underlying molecular mechanisms behind the pathophysiology of PD. Sirtuins are small molecular deacetylases that have an imperative role in pathology of such neurodegenerative disorders like PD. Sirtuins are majorly classified according to their location; nuclear (SIRT1,7,6), mitochondrial sirtuins (SIRT3-5), and cytosolic (SIRT2). These actively take part in pathological development and possess independent actions. In this review, the role of nuclear sirtuins is individualistically explored for better understanding of PD pathology and development of advanced therapeutics targeting sirtuins.

Repurposing ezetimibe as a neuroprotective agent in a rotenone-induced Parkinson's disease model in rats: Role of AMPK/SIRT-1/PGC-1α signaling and autophagy

As a severe neurological disorder, Parkinson's disease (PD) is distinguished by dopaminergic neuronal degeneration in the substantia nigra (SN), culminating in motor impairments. Several studies have shown that activation of the AMPK/SIRT1/PGC1α pathway contributes to an increase in mitochondrial biogenesis and is a promising candidate for the management of PD. Furthermore, turning on the AMPK/SIRT1/PGC1α pathway causes autophagy activation, which is fundamental for maintaining neuronal homeostasis. Interestingly, ezetimibe is an antihyperlipidemic agent that was recently reported to possess pleiotropic properties in neurology by triggering the phosphorylation and activation of AMPK. Thus, our study aimed to investigate the neuroprotective potential of ezetimibe in rats with rotenone-induced PD by activating AMPK. Adult male Wistar rats received rotenone (1.5 mg/kg, s.c.) every other day for 21 days to induce experimental PD. Rats were treated with ezetimibe (5 mg/kg/day, i.p.) 1 h before rotenone. Ezetimibe ameliorated the motor impairments in open field, rotarod and grip strength tests, restored striatal dopamine and tyrosine hydroxylase in the SN, up-regulated p-AMPK, SIRT1, and PGC1α striatal expression, upsurged the expression of ULK1, beclin1, and LC3II/I, reduced Bax/Bcl2 ratio, and alleviated rotenone-induced histopathological changes in striatum and SN. Our findings also verified the contribution of AMPK activation to the neuroprotective effect of ezetimibe by using the AMPK inhibitor dorsomorphin. Together, this work revealed that ezetimibe exerts a neuroprotective impact in rotenone-induced PD by activating AMPK/SIRT-1/PGC-1α signaling, enhancing autophagy, and attenuating apoptosis. Thus, ezetimibe's activation of AMPK could hold significant therapeutic promise for PD management.

SIRT1 Regulates Mitochondrial Damage in N2a Cells Treated with the Prion Protein Fragment 106-126 via PGC-1α-TFAM-Mediated Mitochondrial Biogenesis

Mitochondrial damage is an early and key marker of neuronal damage in prion diseases. As a process involved in mitochondrial quality control, mitochondrial biogenesis regulates mitochondrial homeostasis in neurons and promotes neuron health by increasing the number of effective mitochondria in the cytoplasm. Sirtuin 1 (SIRT1) is a NAD+-dependent deacetylase that regulates neuronal mitochondrial biogenesis and quality control in neurodegenerative diseases via deacetylation of a variety of substrates. In a cellular model of prion diseases, we found that both SIRT1 protein levels and deacetylase activity decreased, and SIRT1 overexpression and activation significantly ameliorated mitochondrial morphological damage and dysfunction caused by the neurotoxic peptide PrP106-126. Moreover, we found that mitochondrial biogenesis was impaired, and SIRT1 overexpression and activation alleviated PrP106-126-induced impairment of mitochondrial biogenesis in N2a cells. Further studies in PrP106-126-treated N2a cells revealed that SIRT1 regulates mitochondrial biogenesis through the PGC-1α-TFAM pathway. Finally, we showed that resveratrol resolved PrP106-126-induced mitochondrial dysfunction and cell apoptosis by promoting mitochondrial biogenesis through activation of the SIRT1-dependent PGC-1α/TFAM signaling pathway in N2a cells. Taken together, our findings further describe SIRT1 regulation of mitochondrial biogenesis and improve our understanding of mitochondria-related pathogenesis in prion diseases. Our findings support further investigation of SIRT1 as a potential target for therapeutic intervention of prion diseases.

SIRT1 improves lactate homeostasis in the brain to alleviate parkinsonism via deacetylation and inhibition of PKM2

Sirtuin 1 (SIRT1) is a histone deacetylase and plays diverse functions in various physiological events, from development to lifespan regulation. Here, in Parkinson's disease (PD) model mice, we demonstrated that SIRT1 ameliorates parkinsonism, while SIRT1 knockdown further aggravates PD phenotypes. Mechanistically, SIRT1 interacts with and deacetylates pyruvate kinase M2 (PKM2) at K135 and K206, thus leading to reduced PKM2 enzyme activity and lactate production, which eventually results in decreased glial activation in the brain. Administration of lactate in the brain recapitulates PD-like phenotypes. Furthermore, increased expression of PKM2 worsens PD symptoms, and, on the contrary, inhibition of PKM2 by shikonin or PKM2-IN-1 alleviates parkinsonism in mice. Collectively, our data indicate that excessive lactate in the brain might be involved in the progression of PD. By improving lactate homeostasis, SIRT1, together with PKM2, are likely drug targets for developing agents for the treatment of neurodegeneration in PD.

Unveiling the interplay of AMPK/SIRT1/PGC-1α axis in brain health: Promising targets against aging and NDDs

The escalating prevalence of neurodegenerative diseases (NDDs) within an aging global population presents a pressing challenge. The multifaceted pathophysiological mechanisms underlying these disorders, including oxidative stress, mitochondrial dysfunction, and neuroinflammation, remain complex and elusive. Among these, the AMPK/SIRT1/PGC-1α pathway emerges as a pivotal network implicated in neuroprotection against these destructive processes. This review sheds light on the potential therapeutic implications of targeting this axis, specifically emphasizing the promising role of flavonoids in mitigating NDD-related complications. Expanding beyond conventional pharmacological approaches, the exploration of non-pharmacological interventions such as exercise and calorie restriction (CR), coupled with the investigation of natural compounds, offers a beacon of hope. By strategically elucidating the intricate connections within these pathways, this review aims to pave the ways for novel multi-target agents and interventions, fostering a renewed optimism in the quest to combat and manage the debilitating impacts of NDDs on global health and well-being.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family in physiological and pathophysiological process and diseases

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family (PGC-1s), consisting of three members encompassing PGC-1α, PGC-1β, and PGC-1-related coactivator (PRC), was discovered more than a quarter-century ago. PGC-1s are essential coordinators of many vital cellular events, including mitochondrial functions, oxidative stress, endoplasmic reticulum homeostasis, and inflammation. Accumulating evidence has shown that PGC-1s are implicated in many diseases, such as cancers, cardiac diseases and cardiovascular diseases, neurological disorders, kidney diseases, motor system diseases, and metabolic disorders. Examining the upstream modulators and co-activated partners of PGC-1s and identifying critical biological events modulated by downstream effectors of PGC-1s contribute to the presentation of the elaborate network of PGC-1s. Furthermore, discussing the correlation between PGC-1s and diseases as well as summarizing the therapy targeting PGC-1s helps make individualized and precise intervention methods. In this review, we summarize basic knowledge regarding the PGC-1s family as well as the molecular regulatory network, discuss the physio-pathological roles of PGC-1s in human diseases, review the application of PGC-1s, including the diagnostic and prognostic value of PGC-1s and several therapies in pre-clinical studies, and suggest several directions for future investigations. This review presents the immense potential of targeting PGC-1s in the treatment of diseases and hopefully facilitates the promotion of PGC-1s as new therapeutic targets.

The interaction between alpha-synuclein and mitochondrial dysfunction in Parkinson's disease

Parkinson's disease (PD) is an aging-associated neurodegenerative disorder with the hallmark of abnormal aggregates of alpha-synuclein (α-syn) in Lewy bodies (LBs) and Lewy neurites (LNs). Currently, pathogenic α-syn and mitochondrial dysfunction have been considered as prominent roles that give impetus to the PD onset. This review describes the α-syn pathology and mitochondrial alterations in PD, and focuses on how α-syn interacts with multiple aspects of mitochondrial homeostasis in the pathogenesis of PD.

Role of P11 through serotonergic and glutamatergic pathways in LID

Parkinson's disease is a progressive neurodegenerative disorder caused by the degeneration of dopaminergic neurons. This leads to the pathogenesis of multiple basal ganglia-thalamomotor loops and diverse neurotransmission alterations. Dopamine replacement therapy, and on top of that, levodopa and l-3,4-dihydroxyphenylalanine (L-DOPA), is the gold standard treatment, while it develops numerous complications. Levodopa-induced dyskinesia (LID) is well-known as the most prominent side effect. Several studies have been devoted to tackling this problem. Studies showed that metabotropic glutamate receptor 5 (mGluR5) antagonists and 5-hydroxytryptamine receptor 1B (5HT1B) agonists significantly reduced LID when considering the glutamatergic overactivity and compensatory mechanisms of serotonergic neurons after L-DOPA therapy. Moreover, it is documented that these receptors act through an adaptor protein called P11 (S100A10). This protein has been thought to play a crucial role in LID due to its interactions with numerous ion channels and receptors. Lately, experiments have shown successful evidence of the effects of P11 blockade on alleviating LID greater than 5HT1B and mGluR5 manipulations. In contrast, there is a trace of ambiguity in the exact mechanism of action. P11 has shown the potential to be a promising target to diminish LID and prolong L-DOPA therapy in parkinsonian patients owing to further studies and experiments.

SIRT1 pathway in Parkinson's disease: a faraway snapshot but so close

Silent information regulator (SIRT) has distinctive enzymatic activities and physiological functions to control cell-cycle progression, gene expression, and DNA stability by targeting histone and non-histone proteins. SIRT1 enhances synaptic formation and synaptic activity, and therefore, can reduce the progression of various degenerative brain diseases including Parkinson's disease (PD). SIRT1 activity is decreased by aging with a subsequent increased risk for the development of degenerative brain diseases. Inhibition of SIRT1 promotes inflammatory reactions since SIRT1 inhibits transcription of nuclear factor kappa B (NF-κB) which also inhibits SIRT1 activation via activation of microRNA and miR-34a which reduce NAD synthesis. SIRT1 is highly expressed in microglia as well as neurons, and has antioxidant and anti-inflammatory effects. Therefore, this review aimed to find the possible role of SIRT1 in PD neuropathology. SIRT1 has neuroprotective effects; therefore, downregulation of SIRT1 during aging promotes p53 expression and may increase the vulnerability of neuronal cell deaths. PD neuropathology is linked with the sequence of inflammatory changes and the release of pro-inflammatory cytokines due to the activation of inflammatory signaling pathways. In addition, oxidative stress, inflammatory disorders, mitochondrial dysfunction, and apoptosis contribute mutually to PD neuropathology. Thus, SIRT1 and SIRT1 activators play a crucial role in the mitigation of PD neuropathology through the amelioration of oxidative stress, inflammatory disorders, mitochondrial dysfunction, apoptosis, and inflammatory signaling pathways.

NLRP3 inflammasomes: A potential target to improve mitochondrial biogenesis in Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative condition for which no approved treatment exists to prevent collective neuronal death. There is ample evidence that mitochondrial dysfunction, reactive oxygen species (ROS), and associated caspase activity underlie the pathology observed. Neurons rely on mitochondrial activity since they have such high energy consumption. Therefore, it is not surprising that mitochondrial alterations favour neuronal degeneration. In particular, mitochondrial dysregulation contributes to PD, based on the observation that mitochondrial toxins can cause parkinsonism in humans and animal models. Also, it is known that inflammatory cytokine-mediated neuroinflammation is the key pathogenic mechanism in neuronal loss. In recent years, the research has focussed on mitochondria being the platform for nucleotide-binding oligomerization domain-like receptors 3 (NLRP3) inflammasome activation. Mitochondrial dysfunction and NLRP3 activation are emerging as critical players in inducing and sustaining neuroinflammation. Moreover, mitochondrial-derived ROS and mitochondrial DNA (mtDNA) could serve as the priming signal for forming inflammasome complexes responsible for the activation, maturation, and release of pro-inflammatory cytokines, including interleukin-1(IL-1) and interleukin-18 (IL-18). The current review takes a more comprehensive approach to elucidating the link between mitochondrial dysfunction and aberrant NLRP3 activation in PD. In addition, we focus on some inhibitors of NLRP3 inflammatory pathways to alleviate the progression of PD.

Association of rare PPARGC1A variants with Parkinson's disease risk

BACKGROUND

Recent researches on Parkinson's disease (PD) pathogenesis discovered the correlation between PD and peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) dysfunction and reduction of PPARGC1A gene expression. Hence, we detected PPARGC1A rare variants to clarify their effect on PD risk in a large population of PD patients in mainland China.

METHODS

We applied whole-exome sequencing (WES) to 1917 patients with early-onset or familial PD and 1652 controls (WES cohort), and whole-genome sequencing (WGS) to 1962 patients with sporadic late-onset PD and 1279 controls (WGS cohort). To identify PPARGC1A rare variants, we used burden analysis to assess the relationship between PPARGC1A rare variants and PD susceptibility.

RESULTS

30 rare missense variants in the cohort WES and 21 missense variants in the cohort WGS have been detected in the study and PPARGC1A missense variants are significantly associated with early-onset and familial PD susceptibility in our study (P = 0.012), which supports evidence that PPARGC1A rare variants are involved in the onset of early-onset and familial PD.

CONCLUSIONS

The study suggested that PPARGC1A rare variants may contribute to the risk of early-onset and familial PD.

Sirtuins and cognition: implications for learning and memory in neurological disorders

Sirtuins are an evolutionarily conserved family of regulatory proteins that function in an NAD+ -dependent manner. The mammalian family of sirtuins is composed of seven histone deacetylase and ADP-ribosyltransferase proteins (SIRT1-SIRT7) that are found throughout the different cellular compartments of the cell. Sirtuins in the brain have received considerable attention in cognition due to their role in a plethora of metabolic and age-related diseases and their ability to induce neuroprotection. More recently, sirtuins have been shown to play a role in normal physiological cognitive function, and aberrant sirtuin function is seen in pathological cellular states. Sirtuins are believed to play a role in cognition through enhancing synaptic plasticity, influencing epigenetic regulation, and playing key roles in molecular pathways involved with oxidative stress affecting mitochondrial function. This review aims to discuss recent advances in the understanding of the role of mammalian sirtuins in cognitive function and the therapeutic potential of targeting sirtuins to ameliorate cognitive deficits in neurological disorders.

Histone Deacetylases as Epigenetic Targets for Treating Parkinson's Disease

Parkinson's disease (PD) is a chronic progressive neurodegenerative disease that is increasingly becoming a global threat to the health and life of the elderly worldwide. Although there are some drugs clinically available for treating PD, these treatments can only alleviate the symptoms of PD patients but cannot completely cure the disease. Therefore, exploring other potential mechanisms to develop more effective treatments that can modify the course of PD is still highly desirable. Over the last two decades, histone deacetylases, as an important group of epigenetic targets, have attracted much attention in drug discovery. This review focused on the current knowledge about histone deacetylases involved in PD pathophysiology and their inhibitors used in PD studies. Further perspectives related to small molecules that can inhibit or degrade histone deacetylases to treat PD were also discussed.

Regulatory Effects of Statins on SIRT1 and Other Sirtuins in Cardiovascular Diseases

Adverse cardiovascular disease (CVD) outcomes, such as sudden cardiac death, acute myocardial infarction, and stroke, are often catastrophic. Statins are frequently used to attenuate the risk of CVD-associated morbidity and mortality through their impact on lipids and they may also have anti-inflammatory and other plaque-stabilization effects via different signaling pathways. Different statins, including atorvastatin, rosuvastatin, pravastatin, pitavastatin, and simvastatin, are administered to manage circulatory lipid levels. In addition, statins are potent inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMGCoA) reductase via modulating sirtuins (SIRTs). During the last two decades, SIRTs have been investigated in mammals and categorized as a family of nicotinamide adenine dinucleotide (NAD)-dependent histone deacetylases (HDACs) with significant oxidative stress regulatory function in cells—a key factor in extending cell lifespan. Recent work has demonstrated that statins upregulate SIRT1 and SIRT2 and downregulate SIRT6 in both in vitro and in vivo experiments and clinical trials. As statins show modulatory properties, especially in CVDs, future investigations are needed to delineate the role of SIRT family members in disease and to expand knowledge about the effects of statins on SIRTs. Here, we review what is currently known about the impact of statins on SIRTs and how these changes correlate with disease, particularly CVDs.

SIRT1 attenuates neuroinflammation by deacetylating HSPA4 in a mouse model of Parkinson's disease

As a deacetylase, SIRT1 plays essential roles in various physiological events, from development to lifespan regulation. SIRT1 has been shown neuroprotective effects in neurodegeneration disorders such as Parkinson's disease (PD). However, the underlying molecular mechanisms are still not well understood. Here, we generated transgenic mice with increased expression of Sirt1 in the brain and examined the potential roles of SIRT1 in PD. Our data showed that SIRT1 repressed proinflammatory cytokine expression both in microglia and astrocytes. In MPTP induced PD model mice, lower levels of microglia and astrocyte activation were observed in SIRT1 transgenic mice. Moreover, the tyrosine hydroxylase (TH) loss in the substantia nigra pars compacta (SNpc) and striatum induced by MPTP was also attenuated by SIRT1. As a consequence, the behavioral defects induced by MPTP were largely prevented in SIRT1 transgenic mice. Mechanistically, SIRT1 interacts with heat shock 70 kDa protein 4 (HSPA4) and deacetylates it at 305, 351 and 605 lysine residues. This deacetylation modification induces the nuclear translocation of HSPA4 and thus to repress proinflammatory cytokine expression. On the contrary, mutated HSPA4, in which 305/351/605 lysine residues were replaced with arginine, was mainly localized in the cytoplasm and losses its repression on proinflammatory cytokine expression. Taken together, our data indicate that SIRT1 plays beneficial roles in PD model mice, which is likely due to, at least in part, its anti-inflammation activity in glial cells by deacetylating HSPA4. Furthermore, HSPA4 might be a druggable target for developing novel agents for treating neuroinflammation associated disorders such as PD.

Sirtuins at the Crossroads between Mitochondrial Quality Control and Neurodegenerative Diseases: Structure, Regulation, Modifications, and Modulators

Sirtuins (SIRT1-SIRT7), a family of nicotinamide adenine dinucleotide (NAD⁺)-dependent enzymes, are key regulators of life span and metabolism. In addition to acting as deacetylates, some sirtuins have the properties of deacylase, decrotonylase, adenosine diphosphate (ADP)-ribosyltransferase, lipoamidase, desuccinylase, demalonylase, deglutarylase, and demyristolyase. Mitochondrial dysfunction occurs early on and acts causally in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD). Sirtuins are implicated in the regulation of mitochondrial quality control, which is highly associated with the pathogenesis of neurodegenerative diseases. There is growing evidence indicating that sirtuins are promising and well-documented molecular targets for the treatment of mitochondrial dysfunction and neurodegenerative disorders by regulating mitochondrial quality control, including mitochondrial biogenesis, mitophagy, mitochondrial fission/fusion dynamics, and mitochondrial unfolded protein responses (mtUPR). Therefore, elucidation of the molecular etiology of sirtuin-mediated mitochondrial quality control points to new prospects for the treatment of neurodegenerative diseases. However, the mechanisms underlying sirtuin-mediated mitochondrial quality control remain obscure. In this review, we update and summarize the current understanding of the structure, function, and regulation of sirtuins with an emphasis on the cumulative and putative effects of sirtuins on mitochondrial biology and neurodegenerative diseases, particularly their roles in mitochondrial quality control. In addition, we outline the potential therapeutic applications for neurodegenerative diseases of targeting sirtuin-mediated mitochondrial quality control through exercise training, calorie restriction, and sirtuin modulators in neurodegenerative diseases.

Gene Therapeutic Approaches for the Treatment of Mitochondrial Dysfunction in Parkinson's Disease

Background: Mitochondrial dysfunction has been identified as a pathophysiological hallmark of disease onset and progression in patients with Parkinsonian disorders. Besides the overall emergence of gene therapies in treating these patients, this highly relevant molecular concept has not yet been defined as a target for gene therapeutic approaches. Methods: This narrative review will discuss the experimental evidence suggesting mitochondrial dysfunction as a viable treatment target in patients with monogenic and idiopathic Parkinson’s disease. In addition, we will focus on general treatment strategies and crucial challenges which need to be overcome. Results: Our current understanding of mitochondrial biology in parkinsonian disorders opens up the avenue for viable treatment strategies in Parkinsonian disorders. Insights can be obtained from primary mitochondrial diseases. However, substantial knowledge gaps and unique challenges of mitochondria-targeted gene therapies need to be addressed to provide innovative treatments in the future. Conclusions: Mitochondria-targeted gene therapies are a potential strategy to improve an important primary disease mechanism in Parkinsonian disorders. However, further studies are needed to address the unique design challenges for mitochondria-targeted gene therapies.

Multifaced role of protein deacetylase sirtuins in neurodegenerative disease

Sirtuins, a class III histone/protein deacetylase, is a central regulator of metabolic function and cellular stress response. This plays a pivotal role in the pathogenesis and progression of diseases such as cancer, neurodegeneration, metabolic syndromes, and cardiovascular disease. Sirtuins regulate biological and cellular processes, for instance, mitochondrial biogenesis, lipid and fatty acid oxidation, oxidative stress, gene transcriptional activity, apoptosis, inflammatory response, DNA repair mechanism, and autophagic cell degradation, which are known components for the progression of the neurodegenerative diseases (NDDs). Emerging evidence suggests that sirtuins are the useful molecular targets against NDDs like, Alzheimer's Disease (AD), Parkinson's Disease (PD), Huntington's Disease (HD), and Amyotrophic Lateral Sclerosis (ALS). However, the exact mechanism of neuroprotection mediated through sirtuins remains unsettled. The manipulation of sirtuins activity with its modulators, calorie restriction (CR), and micro RNAs (miR) is a novel therapeutic approach for the treatment of NDDs. Herein, we reviewed the current putative therapeutic role of sirtuins in regulating synaptic plasticity and cognitive functions, which are mediated through the different molecular phenomenon to prevent neurodegeneration. We also explained the implications of sirtuin modulators, and miR based therapies for the treatment of life-threatening NDDs.