Effects of electroacupuncture on Sirt3/NLRP3/GSDMD signaling pathway in the substantia nigra of midbrain of rats with Parkinson's disease. / ç”µé’ˆå¯¹å¸•é‡‘æ£®ç— å¤§é¼ ä¸­è„‘é»‘è´¨Sirt3/NLRP3/GSDMD信号通路的影响.

OBJECTIVES: To observe the effects on tyrosine hydroxylase (TH), α-synaptic nucleoprotein (α-syn), sirtuin 3 (Sirt3), NOD-like receptor 3 (NLRP3) and gasdermin-D (GSDMD) in the substantia nigra of midbrain after electroacupuncture (EA) at "Fengfu"(GV16), "Taichong" (LR3) and "Zusanli" (ST36) in rats of Parkinson's disease (PD), so as to explore the mechanism of EA in treatment of PD. METHODS: SD rats were randomly divided into control, model and EA groups, with 10 rats in each group. The PD model was established by injecting rotenone into the neck and back, lasting 28 days. In the EA group, EA was applied to GV16, LR3 and ST36, 30 min each time, once daily, consecutively for 28 days. The open-field test was adopted to detect the total distance of autonomic movement of rats, and the pole climbing test was used to detect the body coordination ability of rats. In the substania nigra of midbrain, the positive expression of TH was determined using immunohistochemistry, the mRNA expression levels of α - syn, Sirt3, NLRP3 and GSDMD were detected by quantitative real-time fluorescence PCR, and the protein expression levels of NLRP3, apoptosis-associated speck-like protein containing a caspase-recruitment domain (ASC) and cysteinyl aspartate specific proteinase (Caspase)-1 were detected by Western blot. RESULTS: Compared with the control group, the total distance of autonomous movement was decreased (P<0.01) in the model group, and the score of pole climbing experiment was increased (P<0.01)；in the midbrain substantia nigra the positive expression of TH was decreased (P<0.01)；the mRNA expression level of Sirt3 was decreased (P<0.01), and those of α-syn, NLRP3 and GSDMD were increased (P<0.01)；while the protein expression levels of NLRP3, ASC and Caspase-1 were increased (P<0.01). When compared with the model group, the total distance of autonomous movement in open field experiment was increased (P<0.01) in the EA group and the score of pole climbing experiment was lower (P<0.05)；in the midbrain substantia nigra the positive expression of TH was increased (P<0.01)；the mRNA expression level of Sirt3 in the midbrain substantia nigra was increased (P<0.01), and those of α-syn, NLRP3 and GSDMD were reduced (P<0.01)；while the protein expression levels of NLRP3, ASC and Caspase-1 decreased (P<0.01, P<0.05). CONCLUSIONS: EA at "GV16" "LR3" and "ST36" can repair the neuronal injury, clear the abnormal accumulation of α-syn in the substania nigra of midbrain, and ameliorate mitochondrial damage in PD rats, which may be obtained by regulating Sirt3/NLRP3/GSDMD signaling pathway, so as to delay the occurrence and development of Parkinson's disease.

Gastrodin alleviates mitochondrial dysfunction by regulating SIRT3-mediated TFAM acetylation in vascular dementia.

BACKGROUND: Mitochondrial dysfunction is key to the pathogenesis of vascular dementia (VaD). Sirtuin-3 (SIRT3), an essential member of the sirtuins family, has been proven to be a critical sirtuin in regulating mitochondrial function. The phenolic glucoside gastrodin (GAS), a bioactive ingredient from Gastrodiae Rhizome (known in Chinese as Tian ma) demonstrates significant neuroprotective properties against central nervous system disorders; however, the precise mechanisms through which GAS modulates VaD remain elusive. PURPOSE: This study aims to investigate whether GAS confers a protective role against VaD, and to figure out the underlying molecular mechanisms. METHODS: A bilateral common carotid artery occlusion (BCCAO)-mediated chronic cerebral hypoperfusion (CCH) VaD rat model and a hypoxia model using HT22 cells were employed to investigate pharmacological properties of GAS in mitigating mitochondrial dysfunction. A SIRT3 agonist resveratrol (RES), a SIRT3 inhibitor 3-TYP and SIRT3-knockdown in vitro were used to explore the mechanism of GAS in association with SIRT3. The ability of SIRT3 to bind and deacetylate mitochondrial transcription factor A (TFAM) was detected by immunoprecipitation assay, and TFAM acetylation sites were further validated using mass spectrometry. RESULTS: GAS increased SIRT3 expression and ameliorated mitochondrial structure, mitochondrial respiration, mitochondrial dynamics along with upregulated TFAM, mitigating oxidative stress and senescence. Comparable results were noted with the SIRT3 agonist RES, indicating an impactful neuroprotection played by SIRT3. Specifically, the attenuation of SIRT3 expression through knockdown techniques or exposure to the SIRT3 inhibitor 3-TYP in HT22 cells markedly abrogated GAS-mediated mitochondrial rescuing function. Furthermore, our findings elucidate a novel facet: SIRT3 interacted with and deacetylated TFAM at the K5, K7, and K8 sites. Decreased SIRT3 is accompanied by hyper-acetylated TFAM. CONCLUSION: The present results were the first to demonstrate that the SIRT3/TFAM pathway is a protective target for reversing mitochondrial dysfunction in VaD. The findings suggest that GAS-mediated modulation of the SIRT3/TFAM pathway, a novel mechanism, could ameliorate CCH-induced VaD, offering a potentially beneficial therapeutic strategy for VaD.

Exploring the therapeutic potential of quercetin: A focus on its sirtuin-mediated benefits.

As the global population ages, preventing lifestyle- and aging-related diseases is increasing, necessitating the search for safe and affordable therapeutic interventions. Among nutraceuticals, quercetin, a flavonoid ubiquitously present in various plants, has garnered considerable interest. This review aimed to collate and analyze existing literature on the therapeutic potentials of quercetin, especially its interactions with SIRTs and its clinical applicability based on its bioavailability and safety. This narrative review was based on a literature survey spanning from 2015 to 2023 using PUBMED. The keywords and MeSH terms used were: "quercetin" AND "bioavailability" OR "metabolism" OR "metabolites" as well as "quercetin" AND "SIRTuin" OR "SIRT*" AND "cellular effects" OR "pathway" OR "signaling" OR "neuroprotective" OR "cardioprotective" OR "nephroprotective" OR "antiatherosclerosis" OR "diabetes" OR "antidiabetic" OR "dyslipidemia" AND "mice" OR "rats". Quercetin demonstrates multiple therapeutic activities, including neuroprotective, cardioprotective, and anti-atherosclerotic effects. Its antioxidant, anti-inflammatory, antiviral, and immunomodulatory properties are well-established. At a molecular level, it majorly interacts with SIRTs, particularly SIRT1 and SIRT6, and modulates numerous signaling pathways, contributing to its therapeutic effects. These pathways play roles in reducing oxidative stress, inflammation, autophagy regulation, mitochondrial biogenesis, glucose utilization, fatty acid oxidation, and genome stability. However, clinical trials on quercetin's effectiveness in humans are scarce. Quercetin exhibits a wide range of SIRT-mediated therapeutic effects. Despite the compelling preclinical data, more standardized clinical trials are needed to fully understand its therapeutic potential. Future research should focus on addressing its bioavailability and safety concerns.

[Total saponins of Panax japonicus alleviates CCl4-induced acute liver injury in rats by regulating the PI3K/AktNF-κB signaling pathway].

OBJECTIVE: To investigate the protective effect of total saponins of Panax japonicus (TSPJ) against CCl4-induced acute liver injury (ALI) in rats and explore the underlying pharmacological mechanisms. METHODS: Male SD rat models of CCl4-induced ALI were given intraperitoneal injections of distilled water, 100 mg/kg biphenyl bisabololol, or 50, 100, and 200 mg/kg TSPJ during modeling (n=8). Liver functions (AST, ALT, TBil and ALP) of the rats were assessed and liver pathologies were observed with HE staining. Immunohistochemistry was used to detect the expressions of PI3K/Akt/NF-κB signaling pathway molecules in liver tissue; ELISA was used to determine the levels of T-SOD, GSH-Px, and MDA. Western blotting was performed to detect the expression levels of PI3K-Akt and SIRT6-NF-κB pathways in the liver tissue. RESULTS: Network pharmacological analysis indicated that the key pathways including PI3K/Akt mediated the therapeutic effect of TSPJ on ALI. In the rat models of ALI, treatments with biphenyl bisabololol and TSPJ significantly ameliorated CCl4-induced increase of serum levels AST, ALT, ALP, TBil and MDA and decrease of T-SOD and GSH-Px levels (all P < 0.01). The rat models of ALI showed significantly increased expression of p-NF-κB (P < 0.01), decreased expressions of PI3K, p-Akt and SIRT6 proteins, and elevated expression levels of p-NF-κB, TNF-α and IL-6 proteins in the liver, which were all significantly improved in the treatment groups (P < 0.05 or 0.01). CONCLUSION: TSPJ can effectively alleviate CCl4-induced ALI in rats by suppressing inflammatory responses and oxidative stress in the liver via regulating the PI3K/Akt and SIRT6/NF-κB pathways.

Quercetin inhibits necroptosis in cardiomyocytes after ischemia-reperfusion via DNA-PKcs-SIRT5-orchestrated mitochondrial quality control.

We investigated the mechanism by which quercetin preserves mitochondrial quality control (MQC) in cardiomyocytes subjected to ischemia-reperfusion stress. An enzyme-linked immunosorbent assay was employed in the in vivo experiments to assess myocardial injury markers, measure the transcript levels of SIRT5/DNAPK-cs/MLKL during various time intervals of ischemia-reperfusion, and observe structural changes in cardiomyocytes using transmission electron microscopy. In in vitro investigations, adenovirus transfection was employed to establish a gene-modified model of DNA-PKcs, and primary cardiomyocytes were obtained from a mouse model with modified SIRT5 gene. Reverse transcription polymerase chain reaction, laser confocal microscopy, immunofluorescence localization, JC-1 fluorescence assay, Seahorse energy analysis, and various other assays were applied to corroborate the regulatory influence of quercetin on the MQC network in cardiomyocytes after ischemia-reperfusion. In vitro experiments demonstrated that ischemia-reperfusion injury caused changes in the structure of the myocardium. It was seen that quercetin had a beneficial effect on the myocardial tissue, providing protection. As the ischemia-reperfusion process continued, the levels of DNA-PKcs/SIRT5/MLKL transcripts were also found to change. In vitro investigations revealed that quercetin mitigated cardiomyocyte injury caused by mitochondrial oxidative stress through DNA-PKcs, and regulated mitophagy and mitochondrial kinetics to sustain optimal mitochondrial energy metabolism levels. Quercetin, through SIRT5 desuccinylation, modulated the stability of DNA-PKcs, and together they regulated the "mitophagy-unfolded protein response." This preserved the integrity of mitochondrial membrane and genome, mitochondrial dynamics, and mitochondrial energy metabolism. Quercetin may operate synergistically to oversee the regulation of mitophagy and the unfolded protein response through DNA-PKcs-SIRT5 interaction.

Bushen Tianjing Recipe inhibits human ovarian granulosa cell line KGN apoptosis induced by miR-23a through the regulation of the sirtuin family.

ETHNOPHARMACOLOGICAL RELEVANCE: Bushen Tianjing Recipe (BTR) is a tonic-kidney formula of Traditional Chinese Medicine (TCM) with good therapeutic effects in clinical settings. It was mainly applied to inhibit the decrease of ovarian reserve function in patients. However, the anti-apoptosis mechanism of BTR remains unknown. AIM OF THE STUDY: The formula of BTR is composed of prepared rehmannia root, debark peony root, carapax testudinis and asiatic cornelian cherry fruit. All four components contain the essences of nourishing yin and tonic-kidney. In the theory of TCM, the kidneys store the essence and are primarily responsible for reproduction and development. Hence, we speculated that BTR had some effect on women's reproductive system. In our research, rat serum contains BTR resolved into culture medium for incubation with miR-23a-induced KGN cells to test and determine our hypothesis. MATERIALS AND METHODS: BTR was prepared by the traditional decoction method to collect concentrated liquids for oral administration to rats (15.00 g/kg) for 14 days. The group with miR-23a-induced KGN cells was selected as the positive control, while the mimic one was the control. Pro-apoptosis and anti-apoptosis biomarkers were detected and analyzed by western blot together with upstream transcription factors and intracellular apoptotic signal pathways. RESULTS: The medium- and high-concentration of BRT greatly reduced the apoptosis of miR-23a-induced KGN cells both in mitochondria and cytoplasm. It showed the up-regulation of SIRT1 and SIRT3, the down-regulation of pro-apoptosis factor Bax and apoptotic-related proteins Caspase 3, 8, 9, and the reduction of phosphorylation of ERK1/2 and NF-κB. however, there was no consistency in the group with a low concentration of BTR, compared with those of other groups. CONCLUSION: Our research verified that BTR had a positive effect on women's reproductive system under medium or high concentration, illuminated the intrinsic mechanism at molecular levels, and convinced its potential application values in clinical settings.

Gastrodin alleviates cisplatin nephrotoxicity by inhibiting ferroptosis via the SIRT1/FOXO3A/GPX4 signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Cisplatin (CP) results in acute kidney injury (AKI) and negatively affects patients' therapy and survival. The dried rhizome of Gastrodia elata Blume has been used to treat clinical kidney diseases. Gastrodin (GAS) is an active ingredient of the G. elata tuber. It is unknown whether GAS can alleviate CP-induced AKI. AIM OF THE STUDY: This study aimed to investigate whether GAS, an active ingredient of G. elata Blume, can alleviate CP-induced AKI and to explore its underlying mechanisms. MATERIALS AND METHODS: Experiments were conducted with a CP-induced AKI mouse model and an immortalized human renal tubular epithelial cell line (HK-2). Serum creatinine, Periodic acid-Schiff staining, tissue iron, glutathione, malondialdehyde, and 4-Hydroxynonenal were detected in serum and kidney samples to observe whether GAS inhibits CP-induced tubule ferroptosis. The drug target was verified by detecting the effects of GAS on sirtuin-1 (SIRT1) activity in vitro. Transcriptional regulation of glutathione peroxidase 4 (GPX4) by forkhead box O3A (FOXO3A) was verified by siRNA knockdown, overexpression, and chromatin immunoprecipitation. The effects of FOXO3A, SIRT1, and GAS on CP-induced ferroptosis were measured with propidium iodide, dihydroethidium, monobromobimane, and dipyrromethene boron difluoride staining in HK-2 cells. The relationship between GAS and the SIRT1/FOXO3A/GPX4 pathway was studied using Western blotting. RESULTS: GAS treatment inhibited CP-induced reactive oxygen species, lipid peroxidation, and tubule death in the cell and animal models. GAS activated SIRT1 in vitro. The SIRT1 inhibitor blocked the protective role of GAS in reducing lipid peroxidation in HK-2 cells. FOXO3A transcriptionally regulated GPX4 expression and inhibited CP-induced cell ferroptosis. Compared to CP-damaged mouse kidneys, GAS-treated mice demonstrated significantly increased SIRT1 and GPX4 expression levels, decreased CP-induced acetylation of FOXO3A, and inhibited lipid peroxidation and cell death. CONCLUSIONS: GAS alleviated CP-induced AKI by inhibiting ferroptosis via the SIRT1/FOXO3A/GPX4 signaling pathway. The results offer new insights into the development of new anti-AKI drugs from traditional Chinese medicine.

Wu-zhu-yu Decoction reduces early brain injury following subarachnoid hemorrhage in vivo and in vitro by activating the Nrf2 antioxidant system via SIRT6 targeting.

ETHNOPHARMACOLOGICAL RELEVANCE: Early brain damage (EBI) following subarachnoid hemorrhage (SAH) is a long-lasting condition with a high occurrence. However, treatment options are restricted. Wu-zhu-yu Decoction (WZYD) can treat headaches and vomiting, which are similar to the early symptoms of subarachnoid hemorrhage (SAH). However, it is yet unknown if WZYD can reduce EBI following SAH and its underlying mechanisms. AIM OF THE STUDY: This study aimed to investigate whether WZYD protects against EBI following SAH by inhibiting oxidative stress through activating nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling via Sirtuin 6 (SIRT6)-mediated histone H3 lysine 56 (H3K56) deacetylation. MATERIALS AND METHODS: In the current investigation, the principal components of WZYD were identified using high-performance liquid chromatography-diode array detection (HPLC-DAD). The SAH model in rats using the internal carotid artery plug puncture approach and the SAH model in primary neurons using hemoglobin incubation were developed. WZYD with different doses (137 mg kg-1, 274 mg kg-1, 548 mg kg-1) and the positive drug-Nimodipine (40 mg kg-1) were intragastrically administered in SAH model rats, respectively. The PC12 cells were cultured with corresponding medicated for 24h. In our investigation, neurological scores, brain water content, Evans blue leakage, Nissl staining, TUNEL staining, oxidative stress, expression of apoptosis-related proteins, and Nrf2/HO-1 signaling were evaluated. The interaction between SIRT6 and Nrf2 was detected by co-immunoprecipitation. SIRT6 knockdown was used to confirm its role in WZYD's neuroprotection. RESULTS: The WZYD treatment dramatically reduced cerebral hemorrhage and edema, and enhanced neurological results in EBI following SAH rats. WZYD administration inhibited neuronal apoptosis via reducing the expression levels of Cleaved cysteinyl aspartate specific proteinase-3(Cleaved Caspase-3), cysteinyl aspartate specific proteinase-3(caspase-3), and Bcl-2, Associated X Protein (Bax) and increasing the expression of B-cell lymphoma-2(Bal2). It also decreased reactive oxygen species and malondialdehyde levels and increased Nrf2 and HO-1 expression in the rat brain after SAH. In vitro, WZYD attenuated hemoglobin-induced cytotoxicity, oxidative stress and apoptosis in primary neurons. Mechanistically, WZYD enhanced SIRT6 expression and H3K56 deacetylation, activated Nrf2/HO-1 signaling, and promoted the interaction between SIRT6 and Nrf2. Knockdown of SIRT6 abolished WZYD-induced neuroprotection. CONCLUSIONS: WZYD attenuates EBI after SAH by activating Nrf2/HO-1 signaling through SIRT6-mediated H3K56 deacetylation, suggesting its therapeutic potential for SAH treatment.

Kuntai capsule attenuates premature ovarian insufficiency by activating the FOXO3/SIRT5 signaling pathway in mice: A comprehensive study using UHPLC-LTQ-Orbitrap and integrated pharmacology.

ETHNOPHARMACOLOGICAL RELEVANCE: Classical prescriptions are not only a primary method of clinical treatment in traditional Chinese medicine (TCM) but also represent breakthroughs in the inheritance and development of this field. Kuntai capsule (KTC), a formulation based on a classical prescription, comprises six TCMs: Rehmanniae Radix Praeparata, Coptidis Rhizoma, Paeoniae Radix Alba, Scutellariae Radix, Asini Corii Colla, and Poria. This formulation possesses various beneficial effects, such as nourishing yin and blood, clearing heat and purging fire, and calming the nerves and relieving annoyance. The investigation of the efficacy and mechanism of KTC in regulating anti-aging factors in the treatment of premature ovarian insufficiency (POI) is not only a prominent topic in classical prescription research but also a crucial issue in the treatment of female reproductive aging using TCM. AIM OF THE STUDY: To evaluate the therapeutic effect of KTC on POI and its underlying mechanism. MATERIALS AND METHODS: Healthy and specific pathogen-free (SPF) female Kunming mice aged 6-8 weeks were selected. After acclimatization, the mice were randomly divided into a control, model, and high, middle, and low dose groups of KTC (1.6, 0.8, and 0.4 mg/kg, respectively). Except for the control group, the animals in the other groups were administered a single intraperitoneal injection of 120 mg/kg cyclophosphamide and 30 mg/kg Busulfan to induce the model of POI. After modeling, the mice were treated with the corresponding drugs for 7 days. Serum and ovarian tissues were collected, and the levels of serum follicle-stimulating hormone (FSH), estradiol (E2), and superoxide dismutase 2 (SOD2) were determined using enzyme-linked immunosorbent assay (ELISA). The chemical composition of KTC was characterized and analyzed using ultra-high-pressure liquid chromatography-linear ion trap-Orbitrap tandem mass spectrometry. A "drug-component-target-pathway-disease" network was constructed using network pharmacology research methods to identify the key active components of KTC in treating POI and to elucidate its potential mechanism. The protein expression of the FOXO3/SIRT5 pathway was detected by western blotting. RESULTS: Compared to the model group, the high-dose group of KTC showed a significant increase in ovarian index, significant increase in levels of E2 and SOD2, and a significant decrease in FSH levels. Through systematic analysis of the chemical constituents of KTC, 69 compounds were identified, including 7 organic acids, 14 alkaloids, 28 flavonoids, 15 terpenoids, 2 lignans, 2 phenylpropanoids, and 1 sugar. Based on network pharmacology research methods, it was determined that KTC exerts its therapeutic effect on POI through multiple components (paeoniflorin and malic acid), multiple targets (FOXO3 and SIRT5), and multiple pathways (prolactin signaling pathway, longevity regulating pathway, and metabolic pathways). The accuracy of the network pharmacology prediction was further validated by detecting the protein expression of SIRT5 and FOXO3a, which showed a significant increase in the middle and high-dose groups of KTC compared to the model group. CONCLUSIONS: KTC may effectively treat POI through a multi-component, multi-target, multi-pathway approach, providing an experimental basis for using KTC based on classical prescriptions in the treatment of POI.

Metabolic transitions regulate global protein fatty acylation.

Intermediary metabolites and flux through various pathways have emerged as key determinants of post-translational modifications. Independently, dynamic fluctuations in their concentrations are known to drive cellular energetics in a bi-directional manner. Notably, intracellular fatty acid pools that drastically change during fed and fasted states act as precursors for both ATP production and fatty acylation of proteins. Protein fatty acylation is well regarded for its role in regulating structure and functions of diverse proteins; however, the effect of intracellular concentrations of fatty acids on protein modification is less understood. In this regard, we unequivocally demonstrate that metabolic contexts, viz. fed and fasted states, dictate the extent of global fatty acylation. Moreover, we show that presence or absence of glucose that influences cellular and mitochondrial uptake/utilization of fatty acids and affects palmitoylation and oleoylation, which is consistent with their intracellular abundance in fed and fasted states. Employing complementary approaches including click-chemistry, lipidomics, and imaging, we show the top-down control of cellular metabolic state. Importantly, our results establish the crucial role of mitochondria and retrograde signaling components like SIRT4, AMPK, and mTOR in orchestrating protein fatty acylation at a whole cell level. Specifically, pharmacogenetic perturbations that alter either mitochondrial functions and/or retrograde signaling affect protein fatty acylation. Besides illustrating the cross-talk between carbohydrate and lipid metabolism in mediating bulk post-translational modification, our findings also highlight the involvement of mitochondrial energetics.

Sirtuin 6 ameliorates arthritis through modulating cyclic AMP-responsive element binding protein/CCN1/cyclooxygenase 2 pathway in osteoblasts.

INTRODUCTION: CCN1 is an immediate-early gene product pivotal for arthritis progression. We have previously shown that sirtuin 6 (SIRT6) inhibited hypoxia-induced CCN1 expression in osteoblasts. Herein we examined the contribution of cyclic AMP-responsive element binding protein (CREB)/CRE to this suppressive action and the influence of CCN1 on cyclooxygenase (COX) 2 synthesis. MATERIALS AND METHODS: MC3T3-E1 murine osteoblasts were cultured under normoxia (21% oxygen) or hypoxia (2% oxygen). Expressions of CCN1, phospho-CREB (Ser133), COX2 and relevant kinases were assessed by Western blot. SIRT6 was overexpressed in cultured osteoblasts and arthritic joints by a lentiviral-based technique. Activities of CCN1 gene promoter constructs were examined by luciferase reporter assay. Interaction between CREB and CCN1 promoter was assessed by chromatin immunoprecipitation (ChIP). Collagen-induced arthritis (CIA) was established in 20 rats to evaluate the effects of SIRT6 therapy on osteoblastic expressions of phospho-CREB, CCN1 and COX2. RESULTS: SIRT6 suppressed hypoxia-enhanced CCN1 expression and CREB phosphorylation. Attenuation of calcium/calmodulin-dependent protein kinase II (CaMKII) may be responsible for SIRT6-induced CREB inhibition. CRE at - 286 bp upstream of the ATG start codon was essential for CCN1 expression under hypoxia and SIRT6 reduced hypoxia-stimulated CREB/CRE interaction. Forced expression of CREB rescued SIRT6-suppressed CCN1 synthesis. CCN1 induced COX2 expression in osteoblasts. In rat CIA, the therapeutic effect of SIRT6 was accompanied by decreases in osteoblastic expressions of phospho-CREB, CCN1 and COX2. CONCLUSION: Our study indicated that the benefits of SIRT6 to inflammatory arthritis and bone resorption are at least partially derived from its modulation of CREB/CCN1/COX2 pathway in osteoblasts.

Microglia Sirt6 modulates the transcriptional activity of NRF2 to ameliorate high-fat diet-induced obesity.

BACKGROUND: Microglia play a pivotal role in neuroinflammation, while obesity triggers hypothalamic microglia activation and inflammation. Sirt6 is an important regulator of energy metabolism in many peripheral tissues and hypothalamic anorexic neurons. However, the exact mechanism for microglia Sirt6 in controlling high-fat diet-induced obesity remain unknown. METHODS: Microglia Sirt6 expression levels under various nutritional conditions were measured in the hypothalamus of mice. Also, microglia Sirt6-deficient mice were provided various diets to monitor metabolic changes and hypothalamic inflammatory response. Besides, RNA-seq and Co-IP of microglia with Sirt6 alterations were conducted to further investigate the detailed mechanism by which Sirt6 modulated microglia activity. RESULTS: We found that Sirt6 was downregulated in hypothalamic microglia in mice given a high-fat diet (HFD). Additionally, knockout of microglia Sirt6 exacerbated high-fat diet-induced hypothalamic microglial activation and inflammation. As a result, mice were more prone to obesity, exhibiting a decrease in energy expenditure, impaired glucose tolerance, insulin and leptin resistance, and increased food intake. In vitro, Sirt6 overexpression in BV2 cells displayed protective effects against oleic acid and palmitic acid treatment-derived inflammatory response. Mechanically, Sirt6 deacetylated and stabilised NRF2 to increase the expression of anti-oxidative genes and defend against reactive oxygen species overload. Pharmacological inhibition of NRF2 eliminated the beneficial modulating effects of Sirt6 on microglial activity. CONCLUSION: Collectively, our results revealed that microglial Sirt6 was a primary contributor of microglial activation in the central regulation of obesity. Thus, microglial Sirt6 may be an important therapeutic target for obesity.

Taohong siwu decoction ameliorates cognitive dysfunction through SIRT6/ER stress pathway in Alzheimer's disease.

ETHNOPHARMACOLOGICAL RELEVANCE: A growing number of people suffer from Alzheimer's disease (AD), but there is currently no effective treatment yet. Taohong Siwu Decoction (TSD) has been proved to take strong neuropharmacological activity on dementia, but the effect and mechanism of TSD against AD are still elusive. AIM OF STUDY: To investigate whether TSD could be effective in ameliorating cognitive deficits through SIRT6/ER stress pathway. MATERIALS AND METHODS: Herein, the APP/PS1 mice, an AD model, and HT-22 cell lines were utilized. Different dosages of TSD (4.25, 8.50 and 17.00 g/kg/d) were administered to the mice for 10 weeks by gavage. Following the behavioral tests, oxidative stress levels were measured using malondialdehyde (MDA) and superoxide dismutase (SOD) kits. Nissl staining and Western blot analyses were used to detect the neuronal function. Then, immunofluorescence and Western blot analysis were applied to evaluate silent information regulator 6 (SIRT6) and ER Stress related protein levels in APP/PS1 mice and HT-22 cells. RESULTS: Behavioral tests revealed that APP/PS1 mice administered with TSD orally took more time in the target quadrant, crossed more times in the target quadrant, had a higher recognition coefficient, and spent more time in the central region. In addition, TSD could ameliorate oxidative stress and inhibit neuronal apoptosis in APP/PS1 mice. Furthermore, TSD could up-regulate the SIRT6 protein expression and inhibit ER sensing proteins expressions, such as p-PERK and ATF6, in APP/PS1 mice and Aß1-42-treated HT22 cells. CONCLUSION: According to the abovementioned findings, TSD could alleviate cognitive dysfunction in AD by modulating the SIRT6/ER stress pathway.

Yishen Tongluo formula alleviates diabetic kidney disease through regulating Sirt6/TGF-ß1/Smad2/3 pathway and promoting degradation of TGF-ß1.

ETHNOPHARMACOLOGICAL RELEVANCE: Yishen Tongluo formula (YSTLF) is formulated based on traditional Chinese medicine theory for the treatment of Diabetic kidney disease (DKD) and has been shown to be effective in improving the symptoms of DKD according to the clinical observation. AIM OF THE STUDY: To explore the effect of YSTLF on DKD and figure out whether its effects were due to the regulation Sirt6/TGF-ß1/Smad2/3 pathway and promoting degradation of TGF-ß1. MATERIALS AND METHODS: The extract of YSTLF at 1, 2.5 and 5 g/kg was orally administered to C57BLKS/J (db/db) mice for 8 weeks and db/db mice were given valsartan as a positive control. The littermate db/m and db/db mice were given vehicle as the control and model group, respectively. Blood urea nitrogen and serum creatinine were detected and the urinary albumin excretion, urea albumin creatinine ratio was calculated. The histopathological change of renal tissues in each group was determined. Simultaneously, the levels of fibrosis-related proteins and messenger RNA (mRNA) in kidney and high glucose (HG)-induced SV40-MES-13 cells were detected. The roles of YSTLF in regulating of Sirt6/TGF-ß1/Smad2/3 signaling pathway were investigated in HG-stimulated SV40-MES-13 cells and validated in db/db mice. Furthermore, the effect of YSTLF on TGF-ß1 degradation was investigated in HG-stimulated SV40-MES-13 cells. RESULTS: YSTLF significantly improved the renal function in DKD mice. YSTLF dose-dependently attenuated pathological changes and suppressed the expression of type I collagen, alpha smooth muscle actin, type IV collagen, and fibronectin in vitro and in vivo, resulting in ameliorating of renal fibrosis. YSTLF positively regulated Sirt6 expression, while inhibited the activating of TGF-ß1/Smad2/3 signaling pathway. TGF-ß1 was steady expressed in HG-stimulated SV40-MES-13 cells, whereas was continuously degraded under YSTLF treatment. CONCLUSIONS: YSTLF significantly ameliorates renal damages and fibrosis may via regulating Sirt6/TGF-ß1/Smad2/3 signaling pathway as well as promoting the degradation of TGF-ß1.

Diosgenin attenuates non-alcoholic fatty liver disease in type 2 diabetes through regulating SIRT6-related fatty acid uptake.

BACKGROUND: More than 70% of patients with type 2 diabetes (T2DM) concomitantly suffer from Non-alcoholic fatty liver disease (NAFLD), and the coexistence and interaction of them increases the intractability of NAFLD. With the protective effect against hepatic steatosis and liver fibrosis, SIRT6 is becoming a notable target of NAFLD. Diosgenin, an active monomer from Chinese herbs, has been reported to protect against NAFLD. PURPOSE: This study aims to figure out the mechanism how diosgenin alleviate NAFLD in T2DM and the relationship with SIRT6. METHODS: In vivo studies used spontaneous diabetic db/db mice and divided them into two parts. The first part included four groups consisting of control (Con) group, model (Mod) group, low dose of diosgenin (DL) group and high dose of diosgenin (DH) group. The second part included four groups consisting of Con group, Mod group, DH+OSS (OSS_128167, inhibitor of SIRT6) group, MDL (MDL800, agonist of SIRT6) group. HepG2 cell line was selected in study in vitro, which was mainly composed of six groups including Con group, palmitic acid (PA) group, PA+DL group, PA+DH group, PA+DH+OSS group, PA+MDL group. OGTT, Biochemical biomarker (including TG, TC, AST, ALT), inflammatory biomarker (including IL-6 and TNF-α) were measured. HE, Oil Red O, and DHE staining were conducted. Immunohistochemistry, immunofluorescence, mRNA-seq, and qPCR were used to explore the mechanism. RESULTS: Results in the first part of study in vivo indicated that diosgenin protected against lipid accumulation, oxidative stress, cell injury, and light inflammatory of liver in db/db mice and regulated the expression of SIRT6 and fatty acid transporter including CD36, FATP2, FABP1. The effect of diosgenin could be reversed in DH+OSS group and the same effect was observed in MDL group in the second part of study in vivo. The same results were also noted in followed study in vitro. Diosgenin inhibited the fatty acids uptake and regulated the expression of SIRT6 and fatty acid transporter including CD36, FATP2, and FABP1 in PA-induced hepG2 cells, and which was reversed in DH+OSS group and resembled in MDL group. CONCLUSIONS: Diosgenin could attenuate non-alcoholic fatty liver disease in type 2 diabetes through regulating SIRT6-related fatty acid uptake.

Sodium butyrate activates HMGCS2 to promote ketone body production through SIRT5-mediated desuccinylation.

Ketone bodies have beneficial metabolic activities, and the induction of plasma ketone bodies is a health promotion strategy. Dietary supplementation of sodium butyrate (SB) is an effective approach in the induction of plasma ketone bodies. However, the cellular and molecular mechanisms are unknown. In this study, SB was found to enhance the catalytic activity of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), a rate-limiting enzyme in ketogenesis, to promote ketone body production in hepatocytes. SB administrated by gavage or intraperitoneal injection significantly induced blood ß-hydroxybutyrate (BHB) in mice. BHB production was induced in the primary hepatocytes by SB. Protein succinylation was altered by SB in the liver tissues with down-regulation in 58 proteins and up-regulation in 26 proteins in the proteomics analysis. However, the alteration was mostly observed in mitochondrial proteins with 41% down- and 65% up-regulation, respectively. Succinylation status of HMGCS2 protein was altered by a reduction at two sites (K221 and K358) without a change in the protein level. The SB effect was significantly reduced by a SIRT5 inhibitor and in Sirt5-KO mice. The data suggests that SB activated HMGCS2 through SIRT5-mediated desuccinylation for ketone body production by the liver. The effect was not associated with an elevation in NAD+/NADH ratio according to our metabolomics analysis. The data provide a novel molecular mechanism for SB activity in the induction of ketone body production.

Isoliquiritigenin from licorice flavonoids attenuates NLRP3-mediated pyroptosis by SIRT6 in vascular endothelial cells.

ETHNOPHARMACOLOGIC RELEVANCE: Licorice is a traditional Chinese medicine that has been used for cardiovascular diseases. Recent studies found that supplementation with licorice extracts attenuated the development of atherosclerosis (AS) in hypercholesterolemic patients. Many studies have shown that licorice flavonoids, the main active components of licorice, have a variety of pharmacological effects, including anti-inflammation, regulation of lipid metabolism, and antioxidation. However, the key active components against AS in licorice flavonoids are still unclear. AIM OF THE STUDY: The aim of this paper is to investigate the active components of licorice flavonoids that exert anti-atherosclerotic effects and the underlying mechanisms. MATERIALS AND METHODS: Network pharmacology was used to screen the active components of licorice flavonoids that have anti-atherosclerotic effects. Combining bioinformatics analysis and in vitro studies, the effects and underlying mechanisms of the active component isoliquiritigenin (ISL) on cell pyroptosis were further investigated in tumor necrosis factor (TNF)-α-treated human umbilical vein endothelial cells (HUVECs). RESULTS: We constructed a compound-target network and screened 3 active components, namely, ISL, glabridin, and naringenin in licorice flavonoids. The half maximal effective concentration values of these 3 components suggested that ISL was the key active component against TNF-α-induced endothelial cell injury. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that ISL could potentially treat AS via the nucleotide-binding and oligomerization domain (NOD)-like receptor signaling pathway. An in vitro study verified that ISL suppressed TNF-α-induced NLRP3 activation and pyroptosis in HUVECs. The molecular docking and cellular thermal shift assay showed good compatibility between ISL and class III histone deacetylase sirtuin 6 (SIRT6). Moreover, we found that ISL upregulated the expression of SIRT6 in TNF-α-treated HUVECs. Further study found that SIRT6 knockdown reduced the inhibitory effect of ISL on pyroptosis, whereas the NLRP3 inhibitor reversed this process in TNF-α-treated HUVECs. CONCLUSIONS: Our results demonstrate that ISL is a key active component of licorice flavonoids. ISL attenuates NLRP3-mediated vascular endothelial cell pyroptosis via SIRT6, and SIRT6 may be a potential target of ISL for the treatment of AS.

Sodium butyrate activates HMGCS2 to promote ketone body production through SIRT5-mediated desuccinylation / 医学前沿

Ketone bodies have beneficial metabolic activities, and the induction of plasma ketone bodies is a health promotion strategy. Dietary supplementation of sodium butyrate (SB) is an effective approach in the induction of plasma ketone bodies. However, the cellular and molecular mechanisms are unknown. In this study, SB was found to enhance the catalytic activity of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), a rate-limiting enzyme in ketogenesis, to promote ketone body production in hepatocytes. SB administrated by gavage or intraperitoneal injection significantly induced blood ß-hydroxybutyrate (BHB) in mice. BHB production was induced in the primary hepatocytes by SB. Protein succinylation was altered by SB in the liver tissues with down-regulation in 58 proteins and up-regulation in 26 proteins in the proteomics analysis. However, the alteration was mostly observed in mitochondrial proteins with 41% down- and 65% up-regulation, respectively. Succinylation status of HMGCS2 protein was altered by a reduction at two sites (K221 and K358) without a change in the protein level. The SB effect was significantly reduced by a SIRT5 inhibitor and in Sirt5-KO mice. The data suggests that SB activated HMGCS2 through SIRT5-mediated desuccinylation for ketone body production by the liver. The effect was not associated with an elevation in NAD+/NADH ratio according to our metabolomics analysis. The data provide a novel molecular mechanism for SB activity in the induction of ketone body production.

Luteolin Alleviates Oxidative Stress in Chronic Obstructive Pulmonary Disease Induced by Cigarette Smoke via Modulation of the TRPV1 and CYP2A13/NRF2 Signaling Pathways.

The current study aims to investigate the therapeutic potential of luteolin (Lut), a naturally occurring flavonoid found in various medicinal plants, for treating chronic obstructive pulmonary disease (COPD) through both in vitro and in vivo studies. The results demonstrated that Lut increased body weight, reduced lung tissue swelling and lung damage indices, mitigated systemic oxidative stress levels, and decreased alveolar fusion in cigarette smoke (CS)- and lipopolysaccharide (LPS)-induced COPD mice. Additionally, Lut was observed to downregulate the expression of the TRPV1 and CYP2A13 proteins while upregulating SIRT6 and NRF2 protein expression in CS + LPS-induced COPD mice and cigarette smoke extract (CSE)-treated A549 cells. The concentrations of total reactive oxygen species (ROS) and mitochondrial ROS in A549 cells induced by CSE significantly increased. Moreover, CSE caused a notable elevation of intracellular Ca2+ levels in A549 cells. Importantly, Lut exhibited inhibitory effects on the inward flow of Ca2+ and attenuated the overproduction of mitochondrial and intracellular ROS in A549 cells treated with CSE. In conclusion, Lut demonstrated a protective role in alleviating oxidative stress and inflammation in CS + LPS-induced COPD mice and CSE-treated A549 cells by regulating TRPV1/SIRT6 and CYP2A13/NRF2 signaling pathways.

[Role of SIRTs in cerebral ischemia reperfusion injury and targeted intervention of Chinese medicine].

Cerebral ischemia-reperfusion injury(CIRI) is a complex cascade process and seriously hinders the recovery of patients with acute ischemic stroke, which has become an urgent public health issue to be addressed. Silent information regulators(SIRTs) are a family of nicotinamide adenine dinucleotide(NAD~+)-dependent deacetylases, capable of deacylating the histone and non-histone lysine groups. Accumulating evidence has demonstrated that SIRTs are able to regulate the pathological processes such as oxidative stress, inflammatory response, mitochondrial dysfunction, and programmed cell death of CIRI through post-translational deacetylation, and exert the neuroprotection function. In this study, we reviewed the papers about the role and regulatory mechanisms of SIRTs in the pathological process of CIRI published in the past decade. Further, we summarized the research advance in the prevention and treatment of CIRI with Chinese medicine targeting SIRTs and the related signaling pathways. This review will provide new targets and theoretical support for the clinical application of Chinese medicine in treating CIRI during the occurrence of ischemic stroke.