Advances in characterization of SIRT3 deacetylation targets in mitochondrial function

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

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

The neuroprotective effects of SFGDI on sirtuin 3-related oxidative stress by regulating the Sirt3/SOD/ROS pathway and energy metabolism in BV2 cells

Recently, the investigation of neuroprotective peptides has gained attention in addressing memory impairment and cognitive decline. Although the potential neuroprotective peptide Serine-Phenylalanine-Glycine-Aspartic acid-Isoleucine (SFGDI) has been identified from sea cucumber, the molecular mechanisms remain unclear. This study was conducted to explore the neuroprotection of SFGDI against 3-TYP-induced oxidative stress in BV2 cells. The results showed a retention rate of 76.70% during in vitro simulated gastrointestinal digestion and an absorption rate of 10.41% in a rat-everted gut sac model for SFGDI. Two hours following the administration of SFGDI via gavage in mice, a notable fluorescence was observed in the brain, indicating a potential neuroprotection of SFGDI through its interactions with nerve cells. By utilizing a model of oxidative stress injury induced by 3-TYP in BV2 cells, it was determined that pretreatment with SFGDI (50-200 μg mL-1) resulted in a dose-dependent reduction in the acetylated SOD level, leading to enhanced SOD activity and reduced levels of ROS and MDA. In addition, this pretreatment triggered an increase in unsaturated lipid levels, which helped maintain the intracellular lipid metabolism balance and preserve the mitochondrial function and glycolysis levels to regulate energy metabolism. The results of this study indicate that SFGDI demonstrates neuroprotective properties through its modulation of the Sirt3/SOD/ROS pathway, regulation of lipid metabolism, and enhancement of energy metabolism in BV2 cells. These findings suggest potential novel therapeutic approaches for addressing Sirt3-related memory deficits and neurodegenerative disorders.

Cellular senescence in acute kidney injury: Target and opportunity

Acute kidney injury (AKI) is a common clinical disease with a high incidence and mortality rate. It typically arises from hemodynamic alterations, sepsis, contrast agents, and toxic drugs, instigating a series of events that culminate in tissue and renal damage. This sequence of processes often leads to acute renal impairment, prompting the initiation of a repair response. Cellular senescence is an irreversible arrest of the cell cycle. Studies have shown that renal cellular senescence is closely associated with AKI through several mechanisms, including the promotion of oxidative stress and inflammatory response, telomere shortening, and the down-regulation of klotho expression. Exploring the role of cellular senescence in AKI provides innovative therapeutic ideas for both the prevention and treatment of AKI. Furthermore, it has been observed that targeted removal of senescent cells in vivo can efficiently postpone senescence, resulting in an enhanced prognosis for diseases associated with senescence. This article explores the effects of common anti-senescence drugs senolytics and senostatic and lifestyle interventions on renal diseases, and mentions the rapid development of mesenchymal stem cells (MSCs). These studies have taken senescence-related research to a new level. Overall, this article comprehensively summarizes the studies on cellular senescence in AKI, aiming is to elucidate the relationship between cellular senescence and AKI, and explore treatment strategies to improve the prognosis of AKI.

Regulation mechanisms of sea cucumber peptides against scopolamine-induced memory disorder and novel memory-improving peptides identification

Memory impairment affects cognition and information processing, and attention, leading to a decline in life quality of patients. Previous studies have shown the memory-improving effects of sea cucumber peptides. This study further explored the memory-improving mechanisms of sea cucumber peptides using scopolamine-induced memory-impaired mice and identified novel memory-improving peptides within low molecular weight peptide fractions. The sea cucumber peptides were categorized into three groups based on their molecular weights: SCP-L (molecular weight greater than 10 kDa), SCP-M (weight between 3 kDa and 10 kDa), and SCP-S (molecular weight less than 3 kDa). The results showed that SCP-S improved behavioral performance by regulating cholinergic system disorder and reducing oxidative stress levels, distinguishing itself from SCP-M and SCP-L. Further, SCP-S was found to exhibit a well ability in alleviating the degree of neuroinflammation dependent on microglia and promoting synaptic plasticity. Additionally, a novel memory-improving peptide Ser-Phe-Gly-Asp-Ile (SFGDI) was identified by EASY-nano-LC/MS/MS after simulated digestion-absorption coupling of in silico technologies from SCP-S. SFGDI protected against oxidative stress and regulated cholinergic system in scopolamine-induced PC12 cells. These findings suggest that SCP-S and SFGDI might be considered as potential memory-improving food for people suffering from memory disorders.

SIRT3 regulates mitochondrial function: A promising star target for cardiovascular disease therapy

Dysregulation of mitochondrial homeostasis is common to all types of cardiovascular diseases. SIRT3 regulates apoptosis and autophagy, material and energy metabolism, mitochondrial oxidative stress, inflammation, and fibrosis. As an important mediator and node in the network of mechanisms, SIRT3 is essential to many activities. This review explains how SIRT3 regulates mitochondrial homeostasis and the tricarboxylic acid cycle to treat common cardiovascular diseases. A novel description of the impact of lifestyle factors on SIRT3 expression from the angles of nutrition, exercise, and temperature is provided.

Perampanel attenuates oxidative stress and pyroptosis following subarachnoid hemorrhage via the SIRT3/FOXO3α pathway

Subarachnoid hemorrhage (SAH) occurs most commonly after rupture of an aneurysm, resulting in high disability and mortality due to the absence of effective therapy. Its subsequent stage, early brain injury (EBI), promotes the sustainable development of injury in the brain and ultimately leads to poor prognosis. As a new antiepileptic drug, the effect of perampanel on EBI after SAH is unknown. Pyroptosis, a process of inflammatory programmed cell death, has been confirmed in most studies to play a substantial role in aggravating SAH-post EBI. Similarly, oxidative stress is closely involved in neuronal pyroptosis and the pathophysiological mechanism of SAH-post EBI, leading to a devastating outcome for SAH patients. Nonetheless, no studies have been conducted to determine whether perampanel reduces pyroptosis and oxidative stress in the context of SAH-induced EBI. Rat SAH model via endovascular perforation was constructed in this study, to assess the neuroprotective effect of perampanel on SAH-post EBI, and to clarify the possible molecular mechanism. By means of the neurological score, brain edema detection, FJB staining, immunofluorescence, WB, ELISA, and ROS assay, we found that perampanel can improve neuroscores and reduce brain edema and neuronal degeneration at 24 h after SAH; we also found that perampanel reduced oxidative stress, neuronal pyroptosis, and inhibition of the SIRT3-FOXO3α pathway at 24 h after SAH. When 3-TYP, an inhibitor of SIRT3, was administered, the effects of perampanel on the SIRT3-FOXO3a pathway, antioxidant stress, and neuronal pyroptosis were reversed. Taken together, our data indicate that perampanel attenuates oxidative stress and pyroptosis following subarachnoid hemorrhage via the SIRT3/FOXO3α pathway. This study highlights the application value of perampanel in subarachnoid hemorrhage and lays a foundation for clinical research and later transformation of perampanel in SAH.

Melatonin attenuates monocrotaline-induced hepatic sinusoidal obstruction syndrome in rats via activation of Sirtuin-3

Melatonin possesses potent hepatoprotective properties, but it remains to be elucidated whether melatonin has a therapeutic effect on monocrotaline (MCT)-induced hepatic sinusoidal obstruction syndrome (HSOS). In this study, male Sprague Dawley rats were intraperitoneally injected with melatonin or the same volume of vehicle at 0 and 24 h after MCT intragastric administration. Next, hematoxylin-eosin staining and electron microscopy were performed to evaluate the hepatic sinusoidal injury of rats. Endothelial cell marker RECA-1 was observed by immunohistochemistry. Hepatic oxidative stress was analyzed by detecting malondialdehyde, glutathione S-transferase, and reactive oxygen species. Assessment of liver function was carried out by analysis of serum aspartate aminotransferase, alanine aminotransferase, total bilirubin, and albumin levels. Real-time polymerase chain reaction and Western blot analysis were used to identify liver Sirtuin-3 (SIRT3) and active matrix metallopeptidase 9 (MMP-9) expression. Besides, liver sinusoidal endothelial cells (LSECs) were used for the in vitro functional verification experiment. Specifically, liver histology of the melatonin-treated groups showed that the pathological damages caused by MCT were significantly attenuated, total HSOS scores were decreased, and the elevation of serum hyaluronic acid observed in the model group was also reduced. Moreover, melatonin treatment also improved the survival of rats after partial hepatectomy. Administration of melatonin ameliorated MCT-induced LSECs injury, hepatic oxidative stress, and hepatic dysfunction. Furthermore, melatonin treatment increased SIRT3 expression while attenuating MMP-9 activity in liver tissues. Cell experiment also demonstrated that SIRT3 might mediate the protective effect of melatonin on LSECs. Collectively, our study provided the potential rationale for the application of melatonin for the prevention of MCT-induced HSOS.

Microglia-derived TNF-α contributes to RVLM neuronal mitochondrial dysfunction via blocking the AMPK-Sirt3 pathway in stress-induced hypertension

BACKGROUND

Neuroinflammation in the rostral ventrolateral medulla (RVLM) has been associated with the pathogenesis of stress-induced hypertension (SIH). Neuronal mitochondrial dysfunction is involved in many pathological and physiological processes. However, the impact of neuroinflammation on neuronal mitochondrial homeostasis and the involved signaling pathway in the RVLM during SIH are largely unknown.

METHODS

The morphology and phenotype of microglia and the neuronal mitochondrial injury in vivo were analyzed by immunofluorescence, Western blot, RT-qPCR, transmission electron microscopy, and kit detection. The underlying mechanisms of microglia-derived tumor necrosis factor-α (TNF-α) on neuronal mitochondrial function were investigated through in vitro and in vivo experiments such as immunofluorescence and Western blot. The effect of TNF-α on blood pressure (BP) regulation was determined in vivo via intra-RVLM microinjection of TNF-α receptor antagonist R7050.

RESULTS

The results demonstrated that BP, heart rate (HR), renal sympathetic nerve activity (RSNA), plasma norepinephrine (NE), and electroencephalogram (EEG) power increased in SIH rats. Furthermore, the branching complexity of microglia in the RVLM of SIH rats decreased and polarized into M1 phenotype, accompanied by upregulation of TNF-α. Increased neuronal mitochondria injury was observed in the RVLM of SIH rats. Mechanistically, Sirtuin 3 (Sirt3) and p-AMPK expression were markedly downregulated in both SIH rats and TNF-α-treated N2a cells. AMPK activator A769662 upregulated AMPK-Sirt3 signaling pathway and consequently reversed TNF-α-induced mitochondrial dysfunction. Microinjection of TNF-α receptor antagonist R7050 into the RVLM of SIH rats significantly inhibited the biological activities of TNF-α, increased p-AMPK and Sirt3 levels, and alleviated neuronal mitochondrial injury, thereby reducing c-FOS expression, RSNA, plasma NE, and BP.

CONCLUSIONS

This study revealed that microglia-derived TNF-α in the RVLM impairs neuronal mitochondrial function in SIH possibly through inhibiting the AMPK-Sirt3 pathway. Therefore, microglia-derived TNF-α in the RVLM may be a possible therapeutic target for the intervention of SIH.

Baicalin inhibits pressure overload-induced cardiac hypertrophy by regulating the SIRT3-dependent signaling pathway

BACKGROUND

The conserved sirtuin protein sirtuin 3 (SIRT3) is a vital protective protein for cardiac hypertrophy. Inhibition of SIRT3 accelerated the development of heart hypertrophy. On the other hand, myocardial hypertrophy was prevented by overexpressing SIRT3. SIRT3 has been proposed as a potential therapeutic target for managing or averting heart hypertrophy. Baicalin, a flavonoid extracted from the Scutellaria baicalensis plant, has anti-cardiovascular properties, including protection against cardiac hypertrophy. However, the molecular mechanism of the anti-hypertrophic effect of baicalin is not well known.

PURPOSE

In this study, we aim to investigate the effect of baicalin on cardiac hypertrophy and explored its underlying molecular mechanisms.

STUDY-DESIGN/METHODS

Abdominal aortic constriction (AAC)-induced mouse cardiac hypertrophy and angiotensin II (Ang II)-induced cardiomyocyte hypertrophy models were established. After baicalin treatment, cardiac hypertrophy was monitored by detecting the expression of hypertrophic genes and cell surface area. Echocardiogram was performed to check the heart function in vivo. Moreover, the protein expression of the SIRT3-dependent pathway was detected by Western blotting.

RESULTS

In this work, we demonstrated that baicalin might suppress the cell surface area and the expression of the Ang II -induced myosin heavy chain β (β-MHC), brain natriuretic polypeptide (BNP), and atrial natriuretic factor (ANF). Additionally, it reduced the AAC rats' hypertrophic impact. We also found that baicalin prevents cardiac hypertrophy by regulating SIRT3/LKB1/AMPK signaling pathway. Moreover, we showed that baicalin upregulated the SIRT3 protein expression by inhibiting proteasome and by the activation of 20 S proteasome subunit beta type-5 (PSMB5).

CONCLUSION

These results offer the first proof that baicalin inhibits cardiac hypertrophy due to its effect on the SIRT3-dependent signaling pathway, indicating its potential for treating cardiac hypertrophy and heart failure. The present study provides a preliminary experimental basis for the clinical application of baicalin and baicalin-like compounds.

The lncRNA HOTAIR attenuates pyroptosis of diabetic cardiomyocytes by recruiting FUS to regulate SIRT3 expression

Diabetic cardiomyopathy (DCM) is a serious cardiovascular complication of diabetes that severely affects the quality of life of diabetic patients. Long noncoding RNAs (lncRNAs) play important roles in the pathogenesis of DCM. However, the role of the lncRNA homeobox transcript antisense RNA (HOTAIR) in the progression of DCM remains unclear. The present study aimed to investigate the role of HOTAIR in high glucose (HG)-induced pyroptosis in cardiomyocytes. The expression of the lncRNA HOTAIR, FUS, and SIRT3 in H9C2 cardiomyocytes was detected by RT-qPCR. Western blotting was used to evaluate the expression of FUS and SIRT3 as well as that of pyroptosis- and inflammation-related proteins. RT-qPCR and ELISA were used to determine the expression and secretion of IL-1β and IL-18. RNA pulldown and RIP experiments were used to validate the binding relationship among HOTAIR, FUS, and SIRT3. Flow cytometry was performed to detect pyroptosis. HG induced pyroptosis and elevated the expression of proteins associated with pyroptosis and inflammation (NLRP3, GSDMD-N, cleaved caspase-1, IL-1β, and IL-18) in cardiomyocytes. HOTAIR and SIRT3 levels were decreased in HG-exposed H9C2 cells. Additionally, overexpression of HOTAIR inhibited the HG-induced pyroptosis and inflammatory response in cardiomyocytes. HOTAIR upregulated SIRT3 expression in H9C2 cells by targeting FUS. Moreover, SIRT3 upregulation suppressed HG-mediated pyroptosis of cardiomyocytes. Notably, SIRT3 depletion reversed the inhibitory effect of HOTAIR on HG-triggered pyroptosis in cardiomyocytes. Our research indicates that HOTAIR alleviates pyroptosis in diabetic cardiomyocytes through the FUS/SIRT3 axis, providing a potential marker for the diagnosis and treatment of DCM.

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

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

Sirtuin-3: A potential target for treating several types of brain injury

Sirtuin-3 (SIRT3) is responsible for maintaining mitochondrial homeostasis by deacetylating substrates in an NAD+-dependent manner. SIRT3, the primary deacetylase located in the mitochondria, controls cellular energy metabolism and the synthesis of essential biomolecules for cell survival. In recent years, increasing evidence has shown that SIRT3 is involved in several types of acute brain injury. In ischaemic stroke, subarachnoid haemorrhage, traumatic brain injury, and intracerebral haemorrhage, SIRT3 is closely related to mitochondrial homeostasis and with the mechanisms of pathophysiological processes such as neuroinflammation, oxidative stress, autophagy, and programmed cell death. As SIRT3 is the driver and regulator of a variety of pathophysiological processes, its molecular regulation is significant. In this paper, we review the role of SIRT3 in various types of brain injury and summarise SIRT3 molecular regulation. Numerous studies have demonstrated that SIRT3 plays a protective role in various types of brain injury. Here, we present the current research available on SIRT3 as a target for treating ischaemic stroke, subarachnoid haemorrhage, traumatic brain injury, thus highlighting the therapeutic potential of SIRT3 as a potent mediator of catastrophic brain injury. In addition, we have summarised the therapeutic drugs, compounds, natural extracts, peptides, physical stimuli, and other small molecules that may regulate SIRT3 to uncover additional brain-protective mechanisms of SIRT3, conduct further research, and provide more evidence for clinical transformation and drug development.

Omentin1 ameliorates myocardial ischemia-induced heart failure via SIRT3/FOXO3a-dependent mitochondrial dynamical homeostasis and mitophagy

Background

Adipose tissue-derived adipokines are involved in various crosstalk between adipose tissue and other organs. Omentin1, a novel adipokine, exerts vital roles in the maintenance of body metabolism, insulin resistance and the like. However, the protective effect of omentin1 in myocardial ischemia (MI)-induced heart failure (HF) and its specific mechanism remains unclear and to be elucidated.

Methods

The model of MI-induced HF mice and oxygen glucose deprivation (OGD)-injured cardiomyocytes were performed. Mice with overexpression of omentin1 were constructed by a fat-specific adeno-associated virus (AAV) vector system.

Results

We demonstrated that circulating omentin1 level diminished in HF patients compared with healthy subjects. Furthermore, the fat-specific overexpression of omentin1 ameliorated cardiac function, cardiac hypertrophy, infarct size and cardiac pathological features, and also enhanced SIRT3/FOXO3a signaling in HF mice. Additionally, administration with AAV-omentin1 increased mitochondrial fusion and decreased mitochondrial fission in HF mice, as evidenced by up-regulated expression of Mfn2 and OPA1, and downregulation of p-Drp1(Ser616). Then, it also promoted PINK1/Parkin-dependent mitophagy. Simultaneously, treatment with recombinant omentin1 strengthened OGD-injured cardiomyocyte viability, restrained LDH release, and enhanced the mitochondrial accumulation of SIRT3 and nucleus transduction of FOXO3a. Besides, omentin1 also ameliorated unbalanced mitochondrial fusion-fission dynamics and activated mitophagy, thereby, improving the damaged mitochondria morphology and controlling mitochondrial quality in OGD-injured cardiomyocytes. Interestingly, SIRT3 played an important role in the improvement effects of omentin1 on mitochondrial function, unbalanced mitochondrial fusion-fission dynamics and mitophagy.

Conclusion

Omentin1 improves MI-induced HF and myocardial injury by maintaining mitochondrial dynamical homeostasis and activating mitophagy via upregulation of SIRT3/FOXO3a signaling. This study provides evidence for further application of omentin1 in cardiovascular diseases from the perspective of crosstalk between heart and adipose tissue.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03642-x.

Metabolic reprogramming: A novel therapeutic target in diabetic kidney disease

Diabetic kidney disease (DKD) is one of the most common microvascular complications of diabetes mellitus. However, the pathological mechanisms contributing to DKD are multifactorial and poorly understood. Diabetes is characterized by metabolic disorders that can bring about a series of changes in energy metabolism. As the most energy-consuming organs secondary only to the heart, the kidneys must maintain energy homeostasis. Aberrations in energy metabolism can lead to cellular dysfunction or even death. Metabolic reprogramming, a shift from mitochondrial oxidative phosphorylation to glycolysis and its side branches, is thought to play a critical role in the development and progression of DKD. This review focuses on the current knowledge about metabolic reprogramming and the role it plays in DKD development. The underlying etiologies, pathological damages in the involved cells, and potential molecular regulators of metabolic alterations are also discussed. Understanding the role of metabolic reprogramming in DKD may provide novel therapeutic approaches to delay its progression to end-stage renal disease.

The Role and Mechanism of CREBH Regulating SIRT3 in Metabolic Associated Fatty Liver Disease

AIMS

To investigate the effect of cAMP response element-binding protein H (CREBH) on metabolic associated fatty liver disease by regulating sirtuin 3 (SIRT3).

MAIN METHODS

Two mouse models of fatty liver induced by a methionine-choline deficient (MCD) diet and a high-fat (HF) diet and an in vitro model of palmitic acid (PA) induced lipid-overloaded hepatocytes were constructed to detect the expression of CREBH, SIRT3, total acetylation, and downstream protein interactions and lipid metabolism phenotype, which were further validated in CREBH^-/- mice and lentivirus-overexpressing CREBH hepatocytes.

KEY FINDINGS

In fatty liver and lipid overload models, the expressions of CREBH and SIRT3 were down-regulated and their expression was positively correlated, accompanied by an increase in the level of total protein acetylation. Overexpression of CREBH alleviated excess lipid accumulation, impaired viability, and the ability to metabolize energy through the fatty acid oxidation pathway in hepatocytes in vitro. Furthermore, overexpression of CREBH restored the interaction of the deacetylase SIRT3 with the molecules carnitine palmitoyl-transferase 2 (CPT2) and long-chain acyl CoA dehydrogenase (ACADL) involved in the fatty acid oxidation pathway and their deacetylation status. However, CREBH^-/- aggravated the damage of lipid metabolism in the liver tissue of mice.

SIGNIFICANCE

CREBH increased the enzymatic activity of downstream factors by positively regulating the expression of SIRT3, which promoted the oxidative decomposition of fatty acids in hepatocytes and played an important role in fatty acid oxidation in MAFLD.

The Role and Therapeutic Perspectives of Sirtuin 3 in Cancer Metabolism Reprogramming, Metastasis, and Chemoresistance

Sirtuin 3 (SIRT3), the nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylase, acts as a metabolic modulator mainly located in mitochondria via regulating the process of the relevant biochemical processes by targeting crucial mediators. Recently, owing to its dual role in cancer, SIRT3 has attracted extensive attention. Cancer cells have different metabolic patterns from normal cells, and SIRT3-mediated metabolism reprogramming could be critical in the cancer context, which is closely related to the mechanism of metabolism reprogramming, metastasis, and chemoresistance in tumor cells. Therefore, it is crucial to elucidate the relevant pathological mechanisms and take appropriate countermeasures for the progression of clinical strategies to inhibit the development of cancer. In this review, existing available data on the regulation of cancer metabolism reprogramming, metastasis, and chemoresistance progression of SIRT3 are detailed, as well as the status quo of SIRT3 small molecule modulators is updated in the application of cancer therapy, aiming to highlight strategies directly targeting SIRT3-mediated tumor-suppressing and tumor-promoting, and provide new approaches for therapy application. Furthermore, we offer an effective evidence-based basis for the evolvement of potential personalized therapy management strategies for SIRT3 in cancer settings.

Mammalian Sirtuins and Their Relevance in Vascular Calcification

Cardiovascular diseases are a group of diseases with high morbidity and mortality that affect millions of people each year. Vascular calcification (VC) is an active process that involves the mineral deposition of calcium-phosphate complexes. VC is closely related to cardiovascular diseases, such as hypertension, heart failure, and calcific aortic stenosis, and is a type of ectopic calcification that occurs in the vessel walls. The sirtuins (silent mating-type information regulation 2; SIRTs), are a family of histone deacetylases whose function relies on nicotinamide adenine dinucleotide (NAD+). They have non-negligible functions in the regulation of energy metabolism, senescence, apoptosis, and other biological processes. Sirtuins have important effects on bone homeostasis and VC processes that share many similarities with bone formation. Sirtuins have been confirmed to deacetylate a variety of target proteins related to the occurrence and development of VC, thereby affecting the process of VC and providing new possibilities for the prevention and treatment of cardiovascular diseases. To facilitate the understanding of vascular calcification and accelerate the development of cardiovascular drugs, we reviewed and summarized recent research progress on the relationship between different types of sirtuins and VC.

Emerging Roles of SIRT3 in Cardiac Metabolism

The heart is a highly metabolically active organ that predominantly utilizes fatty acids as an energy substrate. The heart also derives some part of its energy by oxidation of other substrates, including glucose, lactose, amino acids and ketones. The critical feature of cardiac pathology is metabolic remodeling and loss of metabolic flexibility. Sirtuin 3 (SIRT3) is one of the seven mammalian sirtuins (SIRT1 to SIRT7), with NAD⁺ dependent deacetylase activity. SIRT3 is expressed in high levels in healthy hearts but downregulated in the aged or diseased hearts. Experimental evidence shows that increasing SIRT3 levels or activity can ameliorate several cardiac pathologies. The primary deacetylation targets of SIRT3 are mitochondrial proteins, most of which are involved in energy metabolism. Thus, SIRT3 improves cardiac health by modulating cardiac energetics. In this review, we discuss the essential role of SIRT3 in regulating cardiac metabolism in the context of physiology and pathology. Specifically, we summarize the recent advancements that emphasize the critical role of SIRT3 as a master regulator of cardiac metabolism. We also present a comprehensive view of all known activators of SIRT3, and elaborate on their therapeutic potential to ameliorate energetic abnormalities in various cardiac pathologies.

The Role of SIRT3 in the Osteoporosis

SIRT3 is an NAD⁺-dependent deacetylase in the mitochondria with an extensive ability to regulate mitochondrial morphology and function. It has been reported that SIRT3 participates in the occurrence and development of many aging-related diseases. Osteoporosis is a common aging-related disease characterized by decreased bone mass and fragility fractures, which has caused a huge burden on society. Current research shows that SIRT3 is involved in the physiological processes of senescence of bone marrow mesenchymal stem cells (BMSCs), differentiation of BMSCs and osteoclasts. However, the specific effects and mechanisms of SIRT3 in osteoporosis are not clear. In the current review, we elaborated on the physiological functions of SIRT3, the cell types involved in bone remodeling, and the role of SIRT3 in osteoporosis. Furthermore, it also provided a theoretical basis for SIRT3 as a therapeutic target for osteoporosis.

Roles of SIRT6 in kidney disease: a novel therapeutic target

SIRT6 is an NAD+ dependent deacetylase that belongs to the mammalian sirtuin family. SIRT6 is mainly located in the nucleus and regulates chromatin remodeling, genome stability, and gene transcription. SIRT6 extensively participates in various physiological activities such as DNA repair, energy metabolism, oxidative stress, inflammation, and fibrosis. In recent years, the role of epigenetics such as acetylation modification in renal disease has gradually received widespread attention. SIRT6 reduces oxidative stress, inflammation, and renal fibrosis, which is of great importance in maintaining cellular homeostasis and delaying the chronic progression of kidney disease. Here, we review the structure and biological function of SIRT6 and summarize the regulatory mechanisms of SIRT6 in kidney disease. Moreover, the role of SIRT6 as a potential therapeutic target for the progression of kidney disease will be discussed. SIRT6 plays an important role in kidney disease. SIRT6 regulates mitochondrial dynamics and mitochondrial biogenesis, induces G2/M cycle arrest, and plays an antioxidant role in nephrotoxicity, IR, obstructive nephropathy, and sepsis-induced AKI. SIRT6 prevents and delays progressive CKD induced by hyperglycemia, kidney senescence, hypertension, and lipid accumulation by regulating mitochondrial biogenesis, and has antioxidant, anti-inflammatory, and antifibrosis effects. Additionally, hypoxia, inflammation, and fibrosis are the main mechanisms of the AKI-to-CKD transition. SIRT6 plays a critical role in the AKI-to-CKD transition and kidney repair through anti-inflammatory, antifibrotic, and mitochondrial quality control mechanisms. AKI Acute kidney injury, CKD Chronic kidney disease.

Proteomic analysis of lysine acetylation reveals that metabolic enzymes and heat shock proteins may be potential targets for DSS-induced mice colitis

BACKGROUND

Research on acetylation modification and its modification sites will be of great significance for revealing the mechanism of disease and developing new targeted medicines. In this study, we aim to construct a complete atlas of acetylome in the DSS-induced ulcerative colitis mice model (UC model) METHODS: A high-resolution mass spectrometry-based quantitative approach was employed to identify lysine-acetylated proteins and acetylation sites. Bioinformatics analysis and in vitro experiments verified anti-inflammatory effects of HSP90B1-K142ac.

RESULTS

2597 acetylation events and 1914 sites were quantified, highlighting 140 acetylation site changes in the colitis colon tissue. 91 acetylation sites in 75 proteins were up-regulated, and 49 acetylation sites in 39 proteins were down-regulated in the UC models. The differentially acetylated proteins mainly consisted of non-histone proteins located in the cytoplasm and mitochondria. KEGG and protein-protein interaction networks analysis showed that the differentially acetylated proteins were enriched in the TCA cycle, fatty acid metabolism, and protein processing in the endoplasmic reticulum. 68% of the differentially metabolized enzymes have a down-regulated trend in acetylation levels. The acetylation level of lysine 142 in HSP90B1 was found to be obvious in the UC colon, and point mutation of HSP90B1-K142ac would result in the decreasing secretion of TNF-α and IL-2 in LPS-stimulated cultured cells.

CONCLUSION

Our work built a complete atlas of acetylome and revealed the potential role of metabolic enzymes and heat shock proteins in DSS-induced colitis.

Exogenous Nicotinamide Adenine Dinucleotide Attenuates Postresuscitation Myocardial and Neurologic Dysfunction in a Rat Model of Cardiac Arrest

OBJECTIVES

To investigate the therapeutic potential and underlying mechanisms of exogenous nicotinamide adenine dinucleotide+ on postresuscitation myocardial and neurologic dysfunction in a rat model of cardiac arrest.

DESIGN

Thirty-eight rats were randomized into three groups: 1) Sham, 2) Control, and 3) NAD. Except for the sham group, untreated ventricular fibrillation for 6 minutes followed by cardiopulmonary resuscitation was performed in the control and NAD groups. Nicotinamide adenine dinucleotide+ (20 mg/kg) was IV administered at the onset of return of spontaneous circulation.

SETTING

University-affiliated research laboratory.

SUBJECTS

Sprague-Dawley rats.

INTERVENTIONS

Nicotinamide adenine dinucleotide+.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic and myocardial function were measured at baseline and within 4 hours following return of spontaneous circulation. Survival analysis and Neurologic Deficit Score were performed up to 72 hours after return of spontaneous circulation. Adenosine triphosphate (adenosine triphosphate) level was measured in both brain and heart tissue. Mitochondrial respiratory chain function, acetylation level, and expression of Sirtuin3 and NADH dehydrogenase (ubiquinone) 1 alpha subcomplex, 9 (NDUFA9) in isolated mitochondrial protein from both brain and heart tissue were evaluated at 4 hours following return of spontaneous circulation. The results demonstrated that nicotinamide adenine dinucleotide+ treatment improved mean arterial pressure (at 1 hr following return of spontaneous circulation, 94.69 ± 4.25 mm Hg vs 89.57 ± 7.71 mm Hg; p < 0.05), ejection fraction (at 1 hr following return of spontaneous circulation, 62.67% ± 6.71% vs 52.96% ± 9.37%; p < 0.05), Neurologic Deficit Score (at 24 hr following return of spontaneous circulation, 449.50 ± 82.58 vs 339.50 ± 90.66; p < 0.05), and survival rate compared with that of the control group. The adenosine triphosphate level and complex I respiratory were significantly restored in the NAD group compared with those of the control group. In addition, nicotinamide adenine dinucleotide+ treatment activated the Sirtuin3 pathway, down-regulating acetylated-NDUFA9 in the isolated mitochondria protein.

CONCLUSIONS

Exogenous nicotinamide adenine dinucleotide+ treatment attenuated postresuscitation myocardial and neurologic dysfunction. The responsible mechanisms may involve the preservation of mitochondrial complex I respiratory capacity and adenosine triphosphate production, which involves the Sirtuin3-NDUFA9 deacetylation.

SIRT3-mediated mitochondrial unfolded protein response weakens breast cancer sensitivity to cisplatin

BACKGROUND

Mitochondrial unfolded protein response plays an important role in the occurrence and development of breast cancer. However, the role of mitochondrial unfolded protein response (UPR^mt) in the sensitivity of breast cancer to cisplatin chemotherapy has not yet been cleared.

OBJECTIVES

The purpose of this study is to explore the role of mitochondrial unfolded protein response in breast cancer sensitivity to cisplatin.

METHODS

In this study, qRT-PCR, Western blotting, Immunofluorescence, CCK-8, Colony formation, Transwell assay and TUNEL staining assay were used to confirm the role of UPR^mt in breast cancer cells treated with cisplatin.

RESULTS

Cisplatin increased the levels of UPR^mt including CLPP, HSP60, LONP1 in MCF7 and MDA-MB-231 cells. UPR^mt inducer Nicotinamide ribose (NR) could promote the proliferation and invasion of breast cancer cells treated with cisplatin. Importantly, SIRT3 was discovered to increase UPR^mt in breast cancer cells and silencing of SIRT3 could inhibit the effect of NR in breast cancer.

CONCLUSIONS

UPR^mt regulated by SIRT3 could protect breast cancer cell from cisplatin. Controlling SIRT3-induced UPR may be a potential therapeutic target to increase the sensitivity of breast cancer chemotherapy.

Progress on mitochondrial silence information regulator family in epilepsy

SIRT3, SIRT4 and SIRT5 are located in mitochondria and also known as mitochondrial sirtuins. They play important roles in regulating many cellular functions including cell survival, cell cycle or apoptosis, DNA repair and metabolism. Mitochondrial sirtuins are involved in the protection of mitochondrial integrity and energy metabolism under stress regulating the expression of neurotransmitter receptors, neurotrophins, extracellular matrix proteins and various transcription factors, thus involved in epileptogenesis triggered by both genetic or acquired factors. Here we review research progress on the actions of mitochondrial sirtuin in epilepsy; and discuss the challenges and perspectives of mitochondrial sirtuin as a potential therapeutic target for epilepsy.

Protective role of sirtuin3 against oxidative stress and NLRP3 inflammasome in cholesterol accumulation and foam cell formation of macrophages with ox-LDL-stimulation

Sirtuin3 (SIRT3) is involved in reactive oxygen species (ROS), cell metabolism, apoptosis and inflammation. However, the exact role of SIRT3 in macrophages during pathophysiological process of atherosclerosis remains unclear. The present study was to investigate the possible effects and mechanisms of SIRT3 on lipid uptake and foam cells transforming in oxidized low-density lipoprotein (ox-LDL)-stimulated macrophages. Compared with wild-type (WT) mice, SIRT3 deficiency further increased foam cell formation and cellular cholesterol accumulation, exacerbated oxidative stress, impaired mitochondrial permeability potential, decreased optic atrophy 1 (OPA1) but enhanced dynamin-related protein 1 (DRP1) expression, and promoted NLR family pyrin domain-containing protein 3 (NLRP3) activation in ox-LDL-stimulated macrophages from SIRT3 knockout (KO) mice. Dihydromyricetin (DMY), a potential compound to enhance SIRT3 expression, significantly inhibited cellular cholesterol accumulation, suppressed foam cell formation, improved mitochondrial function, attenuated oxidative stress, and alleviated NLRP3 activation in ox-LDL-stimulated macrophages. Moreover, above protective effects of DMY was unavailable in macrophages from SIRT3 KO mice. Collectively, the study demonstrated the protective role of SIRT3 against oxidative stress and NLRP3 inflammasome in cholesterol accumulation and foam cell formation of macrophages with ox-LDL-stimulation, which is beneficial to provide novel strategy for atherosclerosis prevention and treatment.

Targeting Mitochondrial Impairment in Parkinson's Disease: Challenges and Opportunities

The underlying pathophysiology of Parkinson's disease is complex, but mitochondrial dysfunction has an established and prominent role. This is supported by an already large and rapidly growing body of evidence showing that the role of mitochondrial (dys)function is central and multifaceted. However, there are clear gaps in knowledge, including the dilemma of explaining why inherited mitochondriopathies do not usually present with parkinsonian symptoms. Many aspects of mitochondrial function are potential therapeutic targets, including reactive oxygen species production, mitophagy, mitochondrial biogenesis, mitochondrial dynamics and trafficking, mitochondrial metal ion homeostasis, sirtuins, and endoplasmic reticulum links with mitochondria. Potential therapeutic strategies may also incorporate exercise, microRNAs, mitochondrial transplantation, stem cell therapies, and photobiomodulation. Despite multiple studies adopting numerous treatment strategies, clinical trials to date have generally failed to show benefit. To overcome this hurdle, more accurate biomarkers of mitochondrial dysfunction are required to detect subtle beneficial effects. Furthermore, selecting study participants early in the disease course, studying them for suitable durations, and stratifying them according to genetic and neuroimaging findings may increase the likelihood of successful clinical trials. Moreover, treatments involving combined approaches will likely better address the complexity of mitochondrial dysfunction in Parkinson's disease. Therefore, selecting the right patients, at the right time, and using targeted combination treatments, may offer the best chance for development of an effective novel therapy targeting mitochondrial dysfunction in Parkinson's disease.