Effects of moderate intensity training and lithium on spatial learning and memory in a rat model: The role of SIRT3 and PGC1-α expression levels and brain-derived neurotropic factor

In this study we investigated the potential synergistic effects of moderate interval training (MIT) and lithium on spatial learning and memory. Forty-two male Wistar males were classified into six groups including I: Control, II: 10 mg/kg/day IP lithium (Li10), III: MIT, IV: Li10 + MIT, V: 40 mg/kg/day IP lithium (Li40), and VI: Li40 + MIT. Then, the rats underwent Morris Water Maze (MWM) test to assess their spatial memory and learning ability. Brain-derived neurotrophic factor (BDNF) density was measured by enzyme-linked immunosorbent assay (ELISA), and the expression of PGC1 and SIRT3 were assessed via qRT-PCR. The results show that MIT improves both memory and spatial learning; but lithium alone, does not cause this. Additionally, those exposed to a combination of exercise and lithium also had improved spatial learning and memory. Finally, we observed a positive role of BDNF protein, and PGC1 gene on the effects of exercise and lithium.

4'-O-methylbavachalcone alleviates ischemic stroke injury by inhibiting parthanatos and promoting SIRT3

Cerebral ischemia-reperfusion injury (CIRI) can induce massive death of ischemic penumbra neurons via oxygen burst, exacerbating brain damage. Parthanatos is a form of caspase-independent cell death involving excessive activation of PARP-1, closely associated with intense oxidative stress following CIRI. 4'-O-methylbavachalcone (MeBavaC), an isoprenylated chalcone component in Fructus Psoraleae, has potential neuroprotective effects. This study primarily investigates whether MeBavaC can act on SIRT3 to alleviate parthanatos of ischemic penumbra neurons induced by CIRI. MeBavaC was oral gavaged to the middle cerebral artery occlusion-reperfusion (MCAO/R) rats after occlusion. The effects of MeBavaC on cerebral injury were detected by the neurological deficit score and cerebral infarct volume. In vitro, PC-12 cells were subjected to oxygen and glucose deprivation/reoxygenation (OGD/R), and assessed cell viability and cell injury. Also, the levels of ROS, mitochondrial membrane potential (MMP), and intracellular Ca2+ levels were detected to reflect mitochondrial function. We conducted western blotting analyses of proteins involved in parthanatos and related signaling pathways. Finally, the exact mechanism between the neuroprotection of MeBavaC and parthanatos was explored. Our results indicate that MeBavaC reduces the cerebral infarct volume and neurological deficit scores in MCAO/R rats, and inhibits the decreased viability of PC-12 cells induced by OGD/R. MeBavaC also downregulates the expression of parthanatos-related death proteins PARP-1, PAR, and AIF. However, this inhibitory effect is weakened after the use of a SIRT3 inhibitor. In conclusion, the protective effect of MeBavaC against CIRI may be achieved by inhibiting parthanatos of ischemic penumbra neurons through the SIRT3-PARP-1 axis.

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.

Dexmedetomidine alleviates Hypoxia/reoxygenation-induced mitochondrial dysfunction in cardiomyocytes via activation of Sirt3/Prdx3 pathway

BACKGROUND

Myocardial ischemia/reperfusion injury (MIRI) seriously threatens the health of people. The mitochondrial dysfunction in cardiomyocytes can promote the progression of MIRI. Dexmedetomidine (Dex) could alleviate the myocardial injury, which was known to reverse mitochondrial dysfunction in lung injury. However, the function of Dex in mitochondrial dysfunction during MIRI remains unclear.

OBJECTIVE

To assess the function of Dex in mitochondrial dysfunction during MIRI.

METHODS

To investigate the function of Dex in MIRI, H9C2 cells were placed in condition of hypoxia/reoxygenation (H/R). CCK8 assay was performed to test the cell viability, and the mitochondrial membrane potential was evaluated by JC-1 staining. In addition, the binding relationship between Sirt3 and Prdx3 was explored by Co-IP assay. Furthermore, the protein expressions were examined using western blot.

RESULTS

Dex could abolish H/R-induced mitochondrial dysfunction in H9C2 cells. In addition, H/R treatment significantly inhibited the expression of Sirt3, while Dex partially restored this phenomenon. Knockdown of Sirt3 or Prdx3 obviously reduced the protective effect of Dex on H/R-induced mitochondrial injury. Meanwhile, Sirt3 could enhance the function of Prdx3 via deacetylation of Prdx3.

CONCLUSION

Dex was found to attenuate H/R-induced mitochondrial dysfunction in cardiomyocytes via activation of Sirt3/Prdx3 pathway. Thus, this study might shed new lights on exploring new strategies for the treatment of MIRI.

SIRT1 restores mitochondrial structure and function in rats by activating SIRT3 after cerebral ischemia/reperfusion injury

Mitochondrial dysfunction contributes to cerebral ischemia-reperfusion (CI/R) injury, which can be ameliorated by Sirtuin-3 (SIRT3). Under stress conditions, the SIRT3-promoted mitochondrial functional recovery depends on both its activity and expression. However, the approach to enhance SIRT3 activity after CI/R injury remains unelucidated. In this study, Sprague-Dawley (SD) rats were intracranially injected with either adeno-associated viral Sirtuin-1 (AAV-SIRT1) or AAV-sh_SIRT1 before undergoing transient middle cerebral artery occlusion (tMCAO). Primary cortical neurons were cultured and transfected with lentiviral SIRT1 (LV-SIRT1) and LV-sh_SIRT1 respectively before oxygen-glucose deprivation/reoxygenation (OGD/R). Afterwards, rats and neurons were respectively treated with a selective SIRT3 inhibitor, 3-(1H-1,2,3-triazol-4-yl) pyridine (3-TYP). The expression, function, and related mechanism of SIRT1 were investigated by Western Blot, flow cytometry, immunofluorescence staining, etc. After CI/R injury, SIRT1 expression decreased in vivo and in vitro. The simulation and immune-analyses reported strong interaction between SIRT1 and SIRT3 in the cerebral mitochondria before and after CI/R. SIRT1 overexpression enhanced SIRT3 activity by increasing the deacetylation of SIRT3, which ameliorated CI/R-induced cerebral infarction, neuronal apoptosis, oxidative stress, neurological and motor dysfunction, and mitochondrial respiratory chain dysfunction, promoted mitochondrial biogenesis, and retained mitochondrial integrity and mitochondrial morphology. Meanwhile, SIRT1 overexpression alleviated OGD/R-induced neuronal death and mitochondrial bioenergetic deficits. These effects were reversed by AAV-sh_SIRT1 and the neuroprotective effects of SIRT1 were partially offset by 3-TYP. These results suggest that SIRT1 restores the structure and function of mitochondria by activating SIRT3, offering neuroprotection against CI/R injury, which signifies a potential approach for the clinical management of cerebral ischemia.

Effects of electroacupuncture on Sirt3/NLRP3/GSDMD signaling pathway in the substantia nigra of midbrain of rats with Parkinson's disease

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.

Cuscuta chinensis flavonoids alleviate ovarian damage in offspring female mice induced by BPA exposure during pregnancy by regulating the central carbon metabolism pathway

Pregnancy is a sensitive window period for bisphenol A (BPA) exposure. BPA can pass through the placenta and cause reproductive damage in offspring female mice. Even BPA that is not metabolized during lactation can be passed through milk. Cuscuta chinensis flavonoids (CCFs) can alleviate reproductive damage caused by BPA, but the mechanism of action is unclear. To investigate the potential mitigating impact of CCFs on ovarian damage resulting from BPA exposure during pregnancy, we administered BPA and CCFs to pregnant mice during the gestational period spanning from 0.5 to 17.5 days. Aseptic collection of serum and ovaries from female mice was conducted on postnatal day 21 (PND21). Serum hormone levels and tissue receptor levels were quantified utilizing ELISA and PCR, while ovaries underwent sequencing and analysis through transcriptomics and metabolomics techniques. Additionally, the assessment of ovarian oxidative stress levels was carried out as part of the comprehensive analysis. The results showed that CCFs administration mitigated the adverse effects induced by BPA exposure on ovarian index, hormone levels, receptor expression, and mRNA expression levels in female offspring mice. The joint analysis of transcriptome and metabolome revealed 48 enriched pathways in positive ion mode and 44 enriched pathways in negative ion mode. Among them, the central carbon metabolism pathway is significantly regulated by BPA and CCFs. The screened sequencing results were verified through qPCR and biochemical kits. In this study, CCFs may participate in the central carbon metabolism pathway by reducing the expression of Kit proto-oncogene (Kit), hexokinase 1 gene (Hk1) and pyruvate kinase M (Pkm) mRNA and increasing the expression of h-ras proto-oncogene (Hras), sirtuin 3 (Sirt3), sirtuin 6 (Sirt6) and TP53 induced glycolysis regulatory phosphatase gene (Tigar) mRNA, thereby resisting the effects of BPA on the body. At the same time, the metabolic levels of D-Fructose 1,6-bisphosphate and L-Asparagine tend to be stable. Moreover, CCFs demonstrated a capacity to diminish the BPA-induced escalation in reactive oxygen species (ROS) and malondialdehyde (MDA). Simultaneously, it exhibited the ability to elevate levels of glutathione (GSH) and catalase (CAT), thereby effectively preventing peroxidation. In summary, CCFs alleviate BPA-induced ovarian damage in offspring female mice by regulating the central carbon metabolism pathway. This study will improve the information on BPA reproductive damage antagonist drugs and provide a theoretical basis for protecting animal reproductive health.

TSPAN8+ myofibroblastic cancer-associated fibroblasts promote chemoresistance in patients with breast cancer

Cancer-associated fibroblasts (CAFs) are abundant stromal cells in the tumor microenvironment that promote cancer progression and relapse. However, the heterogeneity and regulatory roles of CAFs underlying chemoresistance remain largely unclear. Here, we performed a single-cell analysis using high-dimensional flow cytometry analysis and identified a distinct senescence-like tetraspanin-8 (TSPAN8)+ myofibroblastic CAF (myCAF) subset, which is correlated with therapeutic resistance and poor survival in multiple cohorts of patients with breast cancer (BC). TSPAN8+ myCAFs potentiate the stemness of the surrounding BC cells through secretion of senescence-associated secretory phenotype (SASP)-related factors IL-6 and IL-8 to counteract chemotherapy. NAD-dependent protein deacetylase sirtuin 6 (SIRT6) reduction was responsible for the senescence-like phenotype and tumor-promoting role of TSPAN8+ myCAFs. Mechanistically, TSPAN8 promoted the phosphorylation of ubiquitin E3 ligase retinoblastoma binding protein 6 (RBBP6) at Ser772 by recruiting MAPK11, thereby inducing SIRT6 protein destruction. In turn, SIRT6 down-regulation up-regulated GLS1 and PYCR1, which caused TSPAN8+ myCAFs to secrete aspartate and proline, and therefore proved a nutritional niche to support BC outgrowth. By demonstrating that TSPAN8+SIRT6low myCAFs were tightly associated with unfavorable disease outcomes, we proposed that the combined regimen of anti-TSPAN8 antibody and SIRT6 activator MDL-800 is a promising approach to overcome chemoresistance. These findings highlight that senescence contributes to CAF heterogeneity and chemoresistance and suggest that targeting TSPAN8+ myCAFs is a promising approach to circumvent chemoresistance.

Modulation of the Sirtuin-1 signaling pathway in doxorubicin-induced nephrotoxicity (synergistic amelioration by resveratrol and pirfenidone)

The current study was conducted to determine the precise mechanisms of Sirtuin-1 (Sirt-1), TGF- β (Transforming Growth Factor-β), and long non-coding RNA Metastasis Associated Lung Adenocarcinoma Transcript 1 (LncRNA MALAT-1) in signaling pathways in doxorubicin (DOX)-induced nephrotoxicity. The potential therapeutic effect of Resveratrol and Pirfenidone in DOX toxicity was also assessed. Thirty-six male adult rats were evenly distributed into four groups: Group 1: control rats. Group 2: DOX exposed rats' group, each animal received 7.5 mg/kg DOX as a single intravenous dose, Group 3: DOX exposed group subjected to oral resveratrol (20 mg/kg/daily for two weeks), Group 4: DOX exposed group subjected to oral Pirfenidone (200 mg/kg once daily for 10 days). At the planned time, animals were sacrificed. Renal tissue was collected to assess matrix metalloproteinase-9 (MMP9), inflammatory and apoptotic markers: tumor necrosis factor-alpha (TNF- β, caspase-3, cyclo-oxygenase-2 (COX-2), and oxidative stress markers: nitric oxide (NO), Glutathione (GSH), malondialdehyde (MDA), and superoxide dismutase (SOD). Sirtuin-1 (Sirt-1), TGF-β, and LncRNA MALAT-1 were quantitatively assessed by real-time RT-PCR in the whole blood. Results showed that the DOX group exhibited a significant increase in oxidative stress markers, and inflammatory, and apoptotic markers in the renal tissue. Histologically, the renal tubule lining cells exhibited vacuolar alterations in the cytoplasm, glomerular atrophy, and vascular congestion. Furthermore, renal degeneration was evident, as confirmed by the heightened immuno-expression of MMP9. Exposure to DOX resulted in a significant decrease in Sirtuin-1 (Sirt-1) with a significant increase in the TGFβ, and LncRNA MALAT-1 gene expression. However, pre-treatment with either resveratrol/or Pirefenidone ameliorated the histological renal alterations, regulated the pathways of Sirt-1, TGFβ, and LncRNA MALAT-1, and decreased all oxidative stress, inflammatory and apoptotic markers. In conclusion, DOX exposure leads to renal toxicity by inducing renal degeneration, oxidative stress, and apoptosis. Administration of either resveratrol or Pirfenidone counteracted these changes and protected the kidney against DOX-induced renal damage.

SIRT5 Regulates Ferroptosis through the Nrf2/HO-1 Signaling Axis to Participate in Ischemia-Reperfusion Injury in Ischemic Stroke

This work aimed to study the role and mechanism of SIRT5 regulation of ferroptosis in cerebral ischemia-reperfusion (I/R) injury. A model of middle cerebral artery occlusion in rats was prepared using the method of thread occlusion. The ferroptosis inhibitor was injected intraperitoneally while the SIRT5 interfering lentivirus were injected into the brain, and neurological disorders were scored in the rats. TTC staining was used to detect infarct volume, and immunohistochemistry was used to detect the expression of SIRT5 in tissues. Rat hippocampal neuronal cells H19-7 were transduced with SIRT5 interfering lentivirus and ferroptosis was induced using erastin. The CCK8 detection kit was used to detect cell viability. Commercial kits were used to detect levels of iron ions, ROS, MDA, SOD, and inflammatory factor (TNF-α and IL-6) in brain tissue or cell supernatant. Western blot was used to detect the expression changes of ferroptosis related proteins GPX4, Nrf2, and HO-1 in tissues or cells. Compared with the sham group, the MCAO model group showed higher levels of neurological impairment score, increased cerebral infarction volume, iron ions, inflammatory factors, and oxidative stress levels in rats. Compared with the MCAO group, the MCAO + fer-1 group exhibited lower levels of neurological impairment scores, cerebral infarction volume, decreased iron ions, inflammatory factors, and oxidative stress levels in rats. Meanwhile, compared with the MCAO + DMSO/LV-shRNA group, the MCAO + fer-1/LV-shSIRT5 group showed a significant decrease in neurological impairment scores, cerebral infarction volume, iron ions, inflammatory factors, and oxidative stress levels in rats. In vitro experiments have found that LV-shSIRT5 can prevent erastin-induced cell ferroptosis. In summary, SIRT5 regulates ferroptosis through the Nrf2/HO-1 signaling axis to participate in ischemia-reperfusion injury in ischemic stroke.

Investigating the T regulatory cells and Sirtuin-I serum level in immunotherapy treated house dust mite allergic asthma patients

OBJECTIVES

House dust mite aeroallergens are predominant triggers of frequent asthma attacks among adults and children. The intensity of asthma and immune reaction necessitates treatment alternatives based on adjusting chosen immunity biomarkers to control the exacerbation of symptoms and establish long-term immune tolerance. In this study, we selected CD4+CD25+Foxp3+ regulatory T cells (Tregs), FOXP3, and Sirtuin-1 as they are known to have a potential role in the immune reaction in different allergic diseases. We investigated their interplay during HDM allergic asthma and its respective immunotherapy.

METHODS

Eighty-four subjects were divided into 3 groups; healthy controls (CT), HDM asthma patients without immunotherapy (WOIT), and HDM asthma patients treated with subcutaneous immunotherapy for 6 months before recruitment (WIT). They were enrolled according to the pulmonary function, skin prick tests, and HDM-specific IgE. CD4+ CD25+ and CD4+ CD25+ FOXP3+hi T cells Cell percentages, FOXP3 gene expression, and Sirtuin-1 (Sirt1) serum level were analyzed.

RESULTS

We found that there is a significant difference between WOIT and WIT groups in the CD4+ CD25+ and CD4+ CD25+ FOXP3+hi T cell percentages. While there is no statistically significant difference between WOIT and WIT groups in FOXP3 level. On the controversy, the SIRT1 level in the CT group (4.53 ± 3.880) significantly decreased in the WOIT and WIT groups.

CONCLUSION

This study revealed that both CD4 CD25 and CD4 CD25 high FOXP3 cell percentages increased in the WIT group and declined in the WOIT group. While, FOXP3 gene expression increased in both groups. In addition, the Sirt1 serum level showed some improvement in WIT group after a serious drop in the WOIT group comparing with the CT group. The modulation of these biomarkers for the remission and control of allergic asthma can be a prognostic outcome of immunotherapy which needs to be confirmed by larger scale studies.

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.

Histidine re-sensitizes pediatric acute lymphoblastic leukemia to 6-mercaptopurine through tetrahydrofolate consumption and SIRT5-mediated desuccinylation

Despite progressive improvements in the survival rate of pediatric B-cell lineage acute lymphoblastic leukemia (B-ALL), chemoresistance-induced disease progression and recurrence still occur with poor prognosis, thus highlighting the urgent need to eradicate drug resistance in B-ALL. The 6-mercaptopurine (6-MP) is the backbone of ALL combination chemotherapy, and resistance to it is crucially related to relapse. The present study couples chemoresistance in pediatric B-ALL with histidine metabolism deficiency. Evidence was provided that histidine supplementation significantly shifts the 6-MP dose-response in 6-MP-resistant B-ALL. It is revealed that increased tetrahydrofolate consumption via histidine catabolism partially explains the re-sensitization ability of histidine. More importantly, this work provides fresh insights into that desuccinylation mediated by SIRT5 is an indispensable and synergistic requirement for histidine combination therapy against 6-MP resistance, which is undisclosed previously and demonstrates a rational strategy to ameliorate chemoresistance and protect pediatric patients with B-ALL from disease progression or relapse.

Unravelling HDAC Selectivity for Erasing Acetyl Mark on Lys-5 of Histone H2B

The reversible acetylation of specific Lysine residues of histones plays crucial role in the epigenetic regulation of chromatin activity. Importantly, perturbations of acetylation-deacetylation dynamics have important implications for cancer and neurological disorders. There are 18 human HDACs including sirtuins. The site-selective acetyl eraser specificity of HDACs is poorly defined. Deciphering the site specificity preference of HDACs from a gamut of lysine in histones may be critical for targeted inhibitor development and delineation of regulatory mechanisms associated with chromatin. Here, we have interrogated the propensity of HDACs to erase acetyl mark at Lys-5 of H2B namely, H2BK5Ac engineered by a peptide ligation reaction catalyzed by transpeptidase sortase. HDACs and Sirtuins were individually over-expressed in HEK293 cells and the deacetylation propensity of respective cell lysates was evaluated against H2BK5Ac for initial screening of potential acetyl erasers. This screen indicated HDAC1 as the prime eraser of acetyl mark in H2BK5Ac. The propensity of HDAC1 to erase acetyl mark of H2BK5Ac was further probed using semisynthetic designer nucleosomes with whole cell lysates, recombinant enzyme, and specific inhibitors. Consistent with the above data, siRNA knockdown of HDAC1 and closely related HDAC3 in HEK293 cells prevented the loss of H2BK5 acetylation.

Ubiquitin-specific peptidase 10 attenuates the ferroptosis to promote thyroid cancer malignancy by facilitating GPX4 via elevating SIRT6

PURPOSE

Ubiquitin-specific peptidase 10 (USP10) has been found to have oncogenic activity in several human tumors. This study first revealed the exact function of USP10 on the progression of thyroid cancer (THCA) by researching its effect on the ferroptosis.

METHODS

USP10 expression in THCA patients was analyzed by online data analysis and in 75 THCA cases was scrutinized by real-time quantitative reverse transcription-polymerase chain reaction and Western blot. Influence of USP10 on the viability, colony formation, migration and invasion of THCA cells was demonstrated by cell counting kit-8, colony formation, wound healing and Transwell invasion assays. Effect of USP10 on the Erastin-induced ferroptosis in THCA cells was evaluated by detecting the ferroptosis-related indicators. Intrinsic mechanism of USP10, glutathione peroxidase 4 (GPX4) and sirtuin 6 (SIRT6) in regulating THCA progression was identified. In vivo xenograft experiment was implemented.

RESULTS

USP10 was abundantly expressed in THCA patients, linking to poor outcome. USP10 overexpression enhanced the viability, colony formation, migration and invasion of THCA cells. USP10 mitigated the Erastin-induced ferroptosis in THCA cells, decreased the levels of iron, Fe2+ , malondialdehyde, lipid reactive oxygen species, reduced mitochondrial superoxide level, and increased mitochondrial membrane potential. USP10 facilitated the expression of ferroptosis suppressor GPX4 by elevating SIRT6. Loss of USP10 repressed the in vivo growth of THCA cells.

CONCLUSION

USP10 might attenuate the ferroptosis to promote thyroid cancer malignancy by facilitating GPX4 via elevating SIRT6. It might be novel target for the treatment of THCA.

Binding to nucleosome poises human SIRT6 for histone H3 deacetylation

Sirtuin 6 (SIRT6) is an NAD+-dependent histone H3 deacetylase that is prominently found associated with chromatin, attenuates transcriptionally active promoters and regulates DNA repair, metabolic homeostasis and lifespan. Unlike other sirtuins, it has low affinity to free histone tails but demonstrates strong binding to nucleosomes. It is poorly understood how SIRT6 docking on nucleosomes stimulates its histone deacetylation activity. Here, we present the structure of human SIRT6 bound to a nucleosome determined by cryogenic electron microscopy. The zinc finger domain of SIRT6 associates tightly with the acidic patch of the nucleosome through multiple arginine anchors. The Rossmann fold domain binds to the terminus of the looser DNA half of the nucleosome, detaching two turns of the DNA from the histone octamer and placing the NAD+ binding pocket close to the DNA exit site. This domain shows flexibility with respect to the fixed zinc finger and moves with, but also relative to, the unwrapped DNA terminus. We apply molecular dynamics simulations of the histone tails in the nucleosome to show that in this mode of interaction, the active site of SIRT6 is perfectly poised to catalyze deacetylation of the H3 histone tail and that the partial unwrapping of the DNA allows even lysines close to the H3 core to reach the enzyme.

Specific Inhibitors of Mitochondrial Deacylase Sirtuin 4 Endowed with Cellular Activity

Sirtuins are NAD+-dependent protein lysine deacylases implicated in aging-related diseases. Mammalian Sirtuin 4 (Sirt4) is located in mitochondria and a potential therapeutic target for cancer and metabolic diseases, but no potent and selective Sirt4 inhibitors have been reported. Here, we describe the identification of potent Sirt4-specific small-molecule inhibitors. Testing hits from a target-based virtual screen revealed 12 active compounds. A focused screen based on two top compounds, followed by structure-assisted design of derivatives, yielded four first-in-class potent Sirt4 inhibitors. Kinetic analyses indicate compound competition with the acyl peptide substrate, consistent with the docking models and implicating Sirt4's unique acyl binding site. The compounds indeed show preference for Sirt4 over other isoforms, with one of them (69) being highly isoform selective, and they are active in cells. Our results provide first lead compounds and mechanistic insights for optimization toward Sirt4-specific inhibitors useful as experimental tools and potential therapeutics.

SIRT6 Protects Against Lipopolysaccharide-Induced Inflammation in Human Pulmonary Lung Microvascular Endothelial Cells

Inflammatory response in the pulmonary endothelium drives the pathogenesis of acute lung injury and sepsis. Sirtuin 6 (SIRT6), a member of class III NAD+-dependent deacetylases belonging to the sirtuin family, regulates senescence, metabolism, and inflammation and extends lifespan in mice and model organisms. However, the role of SIRT6 in pulmonary endothelial inflammation is unknown. Thus, we hypothesized that SIRT6 suppresses inflammatory response in human lung microvascular cells (HLMEC) and ensues monocyte adhesion to endothelial cells. Primary HLMECs were treated with control or SIRT6 adenovirus or SIRT6 agonist, with or without lipopolysaccharide (LPS) treatment. We observed that treatment with LPS did not affect the protein expression of SIRT6 in HLMECs. However, adenovirus-mediated SIRT6 overexpression attenuated LPS-induced VCAM1 gene and protein expression, followed by decreased monocyte adhesion to endothelial cells. Similarly, activation of SIRT6 by a recently reported SIRT6 activator UBCS039, but not the regioisomer negative control compound UBCS060, ameliorated LPS-induced VCAM1 mRNA and protein expression as well as monocyte adhesion. Moreover, luciferase assay revealed that SIRT6 adenovirus decreased the activity of NF-κB, the master regulator of vascular inflammation. Taken together, these results indicate that molecular and pharmacological activation of SIRT6 protects against lung microvascular inflammation via suppressing NF-κB activation, implicating the therapeutic potential of the SIRT6 activators for lung disorders associated with microvascular inflammation.

SIRT3/6: an amazing challenge and opportunity in the fight against fibrosis and aging

Fibrosis is a typical aging-related pathological process involving almost all organs, including the heart, kidney, liver, lung, and skin. Fibrogenesis is a highly orchestrated process defined by sequences of cellular response and molecular signals mechanisms underlying the disease. In pathophysiologic conditions associated with organ fibrosis, a variety of injurious stimuli such as metabolic disorders, epigenetic changes, and aging may induce the progression of fibrosis. Sirtuins protein is a kind of deacetylase which can regulate cell metabolism and participate in a variety of cell physiological functions. In this review, we outline our current understanding of common principles of fibrogenic mechanisms and the functional role of SIRT3/6 in aging-related fibrosis. In addition, sequences of novel protective strategies have been identified directly or indirectly according to these mechanisms. Here, we highlight the role and biological function of SIRT3/6 focus on aging fibrosis, as well as their inhibitors and activators as novel preventative or therapeutic interventions for aging-related tissue fibrosis.

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.

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.

Does Selection for Longevity in Acheta domesticus Involve Sirtuin Activity Modulation and Differential Response to Activators (Resveratrol and Nanodiamonds)?

Sirtuins, often called "longevity enzymes", are pivotal in genome protection and DNA repair processes, offering insights into aging and longevity. This study delves into the potential impact of resveratrol (RV) and nanodiamonds (NDs) on sirtuin activity, focusing on two strains of house crickets (Acheta domesticus): the wild-type and long-lived strains. The general sirtuin activity was measured using colorimetric assays, while fluorescence assays assessed SIRT1 activity. Additionally, a DNA damage test and a Kaplan-Meier survival analysis were carried out. Experimental groups were fed diets containing either NDs or RV. Notably, the long-lived strain exhibited significantly higher sirtuin activity compared to the wild-type strain. Interestingly, this heightened sirtuin activity persisted even after exposure to RVs and NDs. These findings indicate that RV and NDs can potentially enhance sirtuin activity in house crickets, with a notable impact on the long-lived strain. This research sheds light on the intriguing potential of RV and NDs as sirtuin activators in house crickets. It might be a milestone for future investigations into sirtuin activity and its potential implications for longevity within the same species, laying the groundwork for broader applications in aging and lifespan extension research.

Posttranslational Acylations of the Rat Brain Transketolase Discriminate the Enzyme Responses to Inhibitors of ThDP-Dependent Enzymes or Thiamine Transport

Transketolase (TKT) is an essential thiamine diphosphate (ThDP)-dependent enzyme of the non-oxidative branch of the pentose phosphate pathway, with the glucose-6P flux through the pathway regulated in various medically important conditions. Here, we characterize the brain TKT regulation by acylation in rats with perturbed thiamine-dependent metabolism, known to occur in neurodegenerative diseases. The perturbations are modeled by the administration of oxythiamine inhibiting ThDP-dependent enzymes in vivo or by reduced thiamine availability in the presence of metformin and amprolium, inhibiting intracellular thiamine transporters. Compared to control rats, chronic administration of oxythiamine does not significantly change the modification level of the two detected TKT acetylation sites (K6 and K102) but doubles malonylation of TKT K499, concomitantly decreasing 1.7-fold the level of demalonylase sirtuin 5. The inhibitors of thiamine transporters do not change average levels of TKT acylation or sirtuin 5. TKT structures indicate that the acylated residues are distant from the active sites. The acylations-perturbed electrostatic interactions may be involved in conformational shifts and/or the formation of TKT complexes with other proteins or nucleic acids. Acetylation of K102 may affect the active site entrance/exit and subunit interactions. Correlation analysis reveals that the action of oxythiamine is characterized by significant negative correlations of K499 malonylation or K6 acetylation with TKT activity, not observed upon the action of the inhibitors of thiamine transport. However, the transport inhibitors induce significant negative correlations between the TKT activity and K102 acetylation or TKT expression, absent in the oxythiamine group. Thus, perturbations in the ThDP-dependent catalysis or thiamine transport manifest in the insult-specific patterns of the brain TKT malonylation and acetylations.

Sirtuins mediate mitochondrial quality control mechanisms: a novel therapeutic target for osteoporosis

Mitochondria plays a role in cell differentiation and apoptosis processes. Maintaining mitochondrial function is critical, and this involves various aspects of mitochondrial quality control such as protein homeostasis, biogenesis, dynamics, and mitophagy. Osteoporosis, a metabolic bone disorder, primarily arises from two factors: the dysregulation between lipogenic and osteogenic differentiation of aging bone marrow mesenchymal stem cells, and the imbalance between osteoblast-mediated bone formation and osteoclast-mediated bone resorption. Mitochondrial quality control has the potential to mitigate or even reverse the effects. Among the Sirtuin family, consisting of seven Sirtuins (SIRT1-7), SIRT1-SIRT6 play a crucial role in maintaining mitochondrial quality control. Additionally, SIRT1, SIRT3, SIRT6, and SIRT7 are directly involved in normal bone development and homeostasis by modulating bone cells. However, the precise mechanism by which these Sirtuins exert their effects remains unclear. This article reviews the impact of various aspects of mitochondrial quality control on osteoporosis, focusing on how SIRT1, SIRT3, and SIRT6 can improve osteoporosis by regulating mitochondrial protein homeostasis, biogenesis, and mitophagy. Furthermore, we provide an overview of the current state of clinical and preclinical drugs that can activate Sirtuins to improve osteoporosis. Specific Sirtuin-activating compounds are effective, but further studies are needed. The findings of this study may offer valuable insights for future research on osteoporosis and the development of clinical prevention and therapeutic target strategies.

Paeonol Attenuates Atherosclerosis by Inhibiting Vascular Smooth Muscle Cells Senescence via SIRT1/P53/TRF2 Signaling Pathway

Atherosclerosis is a chronic inflammatory disease leading to various vascular diseases. Vascular smooth muscle cell (VSMC) senescence promotes atherosclerotic inflammation and the formation of plaque necrosis core, in part through telomere damage mediated by a high-fat diet. Our previous research found that paeonol, a potential anti-inflammatory agent extracted from Cortex Moutan, could significantly improve VSMCs dysfunction. However, the impact of paeonol on the senescence of VSMCs remains unexplored. This study presents the protective effects of paeonol on VSMCs senescence, and its potential activity in inhibiting the progression of atherosclerosis in vivo and in vitro. Sirtuin 1 (SIRT1) is a nuclear deacetylase involved in cell proliferation, senescence, telomere damage, and inflammation. Here, SIRT1 was identified as a potential target of paeonol having anti-senescence and anti-atherosclerosis activity. Mechanistic studies revealed that paeonol binds directly to SIRT1 and then activates the SIRT1/P53/TRF2 pathway to inhibit VSMCs senescence. Our results suggested that SIRT1-mediated VSMCs senescence is a promising druggable target for atherosclerosis, and that pharmacological modulation of the SIRT1/P53/TRF2 signaling pathway by paeonol is of potential benefit for patients with atherosclerosis.

Immunoexpression of SIRT1, 6, and 7 in oral leukoplakia and oral squamous cell carcinoma

Sirtuins (SIRTs) are a family of proteins involved in the metabolic process responsible for extending the lifespan. The role of SIRT1, 6, and 7 in oral squamous cell carcinoma (OSCC) and oral leukoplakia (OLP), one of its precursors, is still elusive. In this study, 82 OLP and 77 OSCC were immunohistochemically examined for SIRT1, 6, and 7. Stained sections were thoroughly scanned and evaluated using a digital image analysis program. The SIRT1, 6, and 7 expressions were detected in the nuclei of epithelial and carcinoma cells in various degrees. Afterward, any correlations among SIRTs, including associations with clinicopathological features and the Kaplan-Meier curves were analyzed. OSCC demonstrated significantly higher SIRT1 expression than OLP, while non-dysplastic lesions showed significantly higher SIRT6 expression than other lesions. A strong correlation was observed between SIRT6 and 7 in OLP, SIRT1 and 6 in in OSCC and in SIRT6 and 7 when all lesion types were considered. There were no significant differences between SIRTs reactivity and the clinical features in OLP. For OSCC, SIRT1 and 6 was found to be directly associated with site of the lesion, while SIRT7 showed a direct relationship between gender, stromal lymphocytic infiltration, and depth of the invasion. OSCC with high SIRT7 expression revealed a slightly lower survival probability, although not statistically significant (p = 0.1019). Our findings suggest that SIRT1, 6, and 7 may play correlated and diverse roles in the development and advancement of OSCC.

Role of sirtuins in attenuating plaque vulnerability in atherosclerosis

Atherosclerosis is characterized by the development of intimal plaque, thrombosis, and stenosis of the vessel lumen causing decreased blood flow and hypoxia precipitating angina. Chronic inflammation in the stable plaque renders it unstable and rupture of unstable plaques results in the formation of emboli leading to hypoxia/ischemia to the organs by occluding the terminal branches and precipitate myocardial infarction and stroke. Such delibitating events could be controlled by the strategies that prevent plaque development or plaque stabilization. Despite the use of statins to stabilize plaques, there is a need for novel targets due to continuously increasing cases of cardiovascular events. Sirtuins (SIRTs), a family of signaling proteins, are involved in sustaining genome integrity, DNA damage response and repair, modulating oxidative stress, aging, inflammation, and energy metabolism. SIRTs play a critical role in modulating inflammation and involves in the development and progression of atherosclerosis. The role of SIRTs in relation to atherosclerosis and plaque vulnerability is scarcely discussed in the literature. Since SIRTs regulate oxidative stress, inflammation, and aging, they may also regulate plaque progression and vulnerability as these molecular mechanisms underlie the pathogenesis of plaque development, progression, and vulnerability. This review critically discusses the role of SIRTs in plaque progression and vulnerability and the possibility of targeting SIRTs to attenuate plaque rupture, focusing on the highlights in genomics, molecular pathways, and cell types involved in the underlying pathophysiology.

The Role of Sirtuin 6 in the Deacetylation of Histone Proteins as a Factor in the Progression of Neoplastic Disease

SIRT6 is a nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase, predominantly located in the nucleus, that is involved in the processes of histone modification, DNA repair, cell cycle regulation, and apoptosis. Disturbances in SIRT6 expression levels have been observed in the development and progression of various types of cancer. Therefore, it is important to better understand the role of SIRT6 in biochemical pathways and assign it specific biological functions. This review aims to summarize the role of SIRT6 in carcinogenesis and tumor development. A better understanding of the factors influencing SIRT6 expression and its biological role in carcinogenesis may help to develop novel anti-cancer therapeutic strategies. Moreover, we discuss the anti-cancer effects and mechanism of action of small molecule SIRT6 modulators (both activators and inhibitors) in different types of cancer.

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.

The Emerging Role of SIRT7 in Glucose and Lipid Metabolism

Sirtuins (SIRT1-7 in mammals) are a family of NAD+-dependent lysine deacetylases and deacylases that regulate diverse biological processes, including metabolism, stress responses, and aging. SIRT7 is the least well-studied member of the sirtuins, but accumulating evidence has shown that SIRT7 plays critical roles in the regulation of glucose and lipid metabolism by modulating many target proteins in white adipose tissue, brown adipose tissue, and liver tissue. This review focuses on the emerging roles of SIRT7 in glucose and lipid metabolism in comparison with SIRT1 and SIRT6. We also discuss the possible implications of SIRT7 inhibition in the treatment of metabolic diseases such as type 2 diabetes and obesity.

Impaired Efferocytosis Enables Apoptotic Osteoblasts to Escape Osteoimmune Surveillance During Aging

Macrophage efferocytosis of apoptotic osteoblasts (apoOBs) is a key osteoimmune process for bone homeostasis. However, apoOBs frequently accumulate in aged bone marrow, where they may mount proinflammatory responses and progressive bone loss. The reason why apoOBs are not cleared during aging remains unclear. In this study, it is demonstrated that aged apoOBs upregulate the immune checkpoint molecule CD47, which is controlled by SIRT6-regulated transcriptional pausing, to evade clearance by macrophages. Using osteoblast- and myeloid-specific gene knockout mice, SIRT6 is further revealed to be a critical modulator for apoOBs clearance via targeting CD47-SIRPα checkpoint. Moreover, apoOBs activate SIRT6-mediated chemotaxis to recruit macrophages by releasing apoptotic vesicles. Two targeting delivery strategies are developed to enhance SIRT6 activity, resulting in rejuvenated apoOBs clearance and delayed age-related bone loss. Collectively, the findings reveal a previously unknown linkage between immune surveillance and bone homeostasis and targeting the SIRT6-regulated mechanism can be a promising therapeutic strategy for age-related bone diseases.

Knockdown of lncRNA MALAT1 induces pyroptosis by regulating the miR‑124/SIRT1 axis in cervical cancer cells

The aim of the present study was to elucidate the role and downstream mechanism of long non‑coding RNA (lncRNA) metastasis‑associated lung adenocarcinoma transcript 1 (MALAT1) in the process of cervical cancer cell pyroptosis. The effect of inhibiting lncRNA MALAT1 on cervical cancer cells was determined using primary cells isolated from patients and U14 cervical tumor‑bearing nude mice. The level of lncRNA MALAT1 expression and cell viability were determined for relationship analysis. Pyroptosis was then investigated in HeLa cells with lncRNA MALAT1 knockdown or overexpression with or without lipopolysaccharide (LPS) treatment. Bioinformatics tools were used to identify downstream factors of lncRNA MALAT1, which were subsequently verified by gain‑ or loss‑of‑function analyses in the process of cervical cancer cell pyroptosis. It was observed that the level of lncRNA MALAT1 was markedly higher in cervical carcinoma cells compared with expression in paracarcinoma cells, and knockdown of lncRNA MALAT1 induced cervical cancer cell death through pyroptosis. By contrast, overexpression of lncRNA MALAT1 blocked LPS‑induced pyroptosis. These results, combined with bioinformatics statistical tools, demonstrated that the microRNA (miR)‑124/sirtuin 1 (SIRT1) axis may affect the progression of cervical cancer at least partly by mediating the effect of lncRNA MALAT1 on the pyroptosis of cervical cancer cells. In conclusion, the lncRNA MALAT1/miR‑124/SIRT1 regulatory axis in cervical cancer cells may mediate pyroptosis and may provide potential targets against the progression of cervical cancer.

Calponin 2 regulates ketogenesis to mitigate acute kidney injury

Calponin 2 (CNN2) is a prominent actin stabilizer. It regulates fatty acid oxidation (FAO) by interacting with estrogen receptor 2 (ESR2) to determine kidney fibrosis. However, whether CNN2 is actively involved in acute kidney injury (AKI) remains unclear. Here, we report that CNN2 was induced in human and animal kidneys after AKI. Knockdown of CNN2 preserved kidney function, mitigated tubular cell death and inflammation, and promoted cell proliferation. Distinct from kidney fibrosis, proteomics showed that the key elements in the FAO pathway had few changes during AKI, but we identified that 3-hydroxymethylglutaryl-CoA synthase 2 (Hmgcs2), a rate-limiting enzyme of endogenous ketogenesis that promotes cell self-renewal, was markedly increased in CNN2-knockdown kidneys. The production of ketone body β-hydroxybutyrate and ATP was increased in CNN2-knockdown mice. Mechanistically, CNN2 interacted with ESR2 to negatively regulate the activities of mitochondrial sirtuin 5. Activated sirtuin 5 subsequently desuccinylated Hmgcs2 to produce energy for mitigating AKI. Understanding CNN2-mediated discrete fine-tuning of protein posttranslational modification is critical to optimize organ performance after AKI.

SIRT6's function in controlling the metabolism of lipids and glucose in diabetic nephropathy

Diabetic nephropathy (DN) is a complication of diabetes mellitus (DM) and the main cause of excess mortality in patients with type 2 DM. The pathogenesis and progression of DN are closely associated with disorders of glucose and lipid metabolism. As a member of the sirtuin family, SIRT6 has deacetylation, defatty-acylation, and adenosine diphosphate-ribosylation enzyme activities as well as anti-aging and anticancer activities. SIRT6 plays an important role in glucose and lipid metabolism and signaling, especially in DN. SIRT6 improves glucose and lipid metabolism by controlling glycolysis and gluconeogenesis, affecting insulin secretion and transmission and regulating lipid decomposition, transport, and synthesis. Targeting SIRT6 may provide a new therapeutic strategy for DN by improving glucose and lipid metabolism. This review elaborates on the important role of SIRT6 in glucose and lipid metabolism, discusses the potential of SIRT6 as a therapeutic target to improve glucose and lipid metabolism and alleviate DN occurrence and progression of DN, and describes the prospects for future research.

SIRT6 pharmacological inhibition delays skin cancer progression in the squamous cell carcinoma

Sirtuin 6 (SIRT6) has a critical role in cutaneous Squamous Cell Carcinoma (cSCC): SIRT6 silencing in skin SCC cells has pro-differentiating effects and SIRT6 deletion abrogated DMBA-TPA-induced skin tumorigenesis in mice. On the other hand, SIRT6 acts as tumor suppressor in SCC by enhancing glycolysis in tumor propagating cells. Herein, pharmacological modulation of SIRT6 deacetylase activity was investigated in cSCC, with S6 (inhibitor) or MDL-800 (activator). In cSCC cells, S6 recreated the pro-differentiating effects of SIRT6 silencing, as the levels of Keratin 1, Keratin 10 and Loricrin were upregulated compared to controls. Next, the effects of SIRT6 pharmacological modulation were evaluated in a DMBA-TPA-induced skin cancer mouse model. Mice treated with the inhibitor S6 in a preventive approach, i.e. at the beginning of the promotion stage, presented reduced number and size of papillomas, compared to the controls. The epidermal hyperproliferation marker Keratin 6 and the cSCC marker Keratin 8 were less abundant when SIRT6 was inhibited. In S6-treated lesions, the Epithelial-Mesenchymal Transition (EMT) markers Zeb1 and Vimentin were less expressed compared to untreated lesions. In a therapeutic approach, i.e. treatment starting after papilloma appearance, the S6 group presented reduced papillomas (number and size), whereas MDL-800-treated mice displayed an opposite trend. In S6-treated lesions, Keratin 6 and Keratin 8 were less expressed, EMT was less advanced, with a higher E-cadherin/Vimentin ratio, indicating a delayed carcinogenesis when SIRT6 was inhibited. Our results confirm that SIRT6 plays a role in skin carcinogenesis and suggest SIRT6 pharmacological inhibition as a promising strategy in cSCC.

Design, synthesis and biological evaluation of 2,4,6- trisubstituted triazine derivatives as new nonpeptide small-molecule SIRT5 inhibitors

Human sirtuin 5 (SIRT5) participates in a variety of metabolic disorder-associated diseases, including cancer. Inhibition of SIRT5 has been confirmed to provide a new strategy for treatment of related diseases. Previously, we discovered a pyrimidine skeleton inhibitor XIV, which showed low micromolar inhibitory activity against SIRT5. Herein, we utilized the scaffold-hopping strategy to design and synthesize a series of 2,4,6- trisubstituted triazine derivatives. The SAR analysis led to the discovery of several new SIRT5 inhibitors with low micromolar inhibition levels. The most potent compounds 10 (IC50 = 5.38 µM), and 14 (IC50 = 4.07 µM) were further confirmed to be the substrate-competitive SIRT5 inhibitors through enzyme kinetic assays, which is consistent with the molecular docking analyses. Fluorescence-based thermal shift assays proved that these compounds may stabilize SIRT5 by binding withprotein.. In addition, compounds 10 and 14 were also revealed to have moderate selectivity to SIRT5 over SIRT1-3. This study will aid further efforts to develop highly potent and selective SIRT5 inhibitors for the treatment of cancer and other related diseases.

Hesperetin attenuates cognitive dysfunction via SIRT6/NLRP3 pathway in scopolamine-induced mice

Neuroinflammation is a critical feature in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). Hesperetin can exert anti-inflammatory, antioxidant and other neuroprotective effects. In this study, the scopolamine (SCOP)-induced cognitive dysfunction in mice model was used to evaluate the neuroprotective effects of hesperetin. Behavioral tests (Morris water maze, open field, and novel object recognition tests) were conducted to evaluate the effect of hesperetin on cognitive dysfunction behaviors. Nissl staining and Immunofluorescence were used to evaluate hippocampal neuronal damage and microglial activation in mice. The levels of proinflammatory factors, oxidant stress, and the cholinergic neurotransmitter were detected by real-time quantitative fluorescence PCR (RT-qPCR) or biochemical reagent kits. Western blotting was used to detect the relative protein expression of the sirtuin 6 (SIRT6) / NOD-like receptor thermal protein domain associated protein 3 (NLRP3) pathway. Results showed that hesperetin could ameliorate SCOP-induced cognitive impairment and neuronal damage, and regulate the levels of cholinergic neurotransmitters in the hippocampal of AD mice. Hesperetin could also enhance antioxidant defense by regulating the levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT). Hesperetin exerted anti-neuroinflammation effects through inhibiting of microglia activation and down-regulating the mRNA transcript levels of inflammatory cytokines, such as tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS). Meanwhile, hesperetin could attenuate the expression of NLRP3, apoptosis-associated speck-like protein containing a CARD (ASC), thioredoxin-interacting protein (TXNIP), and caspase-1 p20 and upregulate the expression of SIRT6 in SCOP-induced mice. Overall, our study suggested that hesperetin might ameliorate SCOP-induced cognitive dysfunction by improving cholinergic system dysfunction and suppressing oxidative stress and attenuating neuroinflammation via SIRT6/NLRP3 pathway in mice.

The effects of Spirulina platensis on behavior in adolescent rats fed a high-fat diet

In recent years, childhood overweight and obesity have become a universal public health problem. Obesity may lead to cognitive disorders, depression and anxiety by affecting neuronal processes. Spirulina platensis (SP), a species of microalgae from the Chlorophyceae green algae class, has neuroprotective effects and may reduce body weight. In this study, we aimed to investigate the effects of SP on behavior alongside the role of leptin and Sirtuin-1 in fed with high-fat diet (HFD) adolescent rats. Four-week-old Sprague Dawley male rats were divided into four groups: control, HFD, HFD + SP150 (150 mg/kg/day SP, orally), HFD + SP450 (450 mg/kg/day SP, orally). Rats except for the control group exposed to 60% HFD along 12 weeks. Last 6 weeks SP or vehicle administered. After the behavioral tests, leptin and Sirtuin-1 levels in prefrontal cortex and hippocampus regions were evaluated. SP150 significantly reduced body weight compared with HFD group. The time spent in the center of open field increased significantly in SP150-treated rats compared with HFD. SP150 and SP450 significantly decreased immobility time in forced swim test compared with HFD. Leptin levels in HFD group were significantly lower in prefrontal cortex compared to control group. Leptin levels of the HFD + SP450 group were significantly higher than HFD group in the hippocampus. There was no significant difference between groups in Sirtuin-1 levels. In conclusion, SP supplementation in adolescence period might positively affect chronic high fat-induced anxiety-like and depressive-like behavior by partially affecting brain leptin levels and without affecting Sirtuin-1 levels.

Recombinant Human HAPLN1 Mitigates Pulmonary Emphysema by Increasing TGF-β Receptor I and Sirtuins Levels in Human Alveolar Epithelial Cells

Chronic obstructive pulmonary disease (COPD) will be the third leading cause of death worldwide by 2030. One of its components, emphysema, has been defined as a lung disease that irreversibly damages the lungs' alveoli. Treatment is currently unavailable for emphysema symptoms and complete cure of the disease. Hyaluronan (HA) and proteoglycan link protein 1 (HAPLN1), an HA-binding protein linking HA in the extracellular matrix to stabilize the proteoglycan structure, forms a bulky hydrogel-like aggregate. Studies on the biological role of the full-length HAPLN1, a simple structure-stabilizing protein, are limited. Here, we demonstrated for the first time that treating human alveolar epithelial type 2 cells with recombinant human HAPLN1 (rhHAPLN1) increased TGF-β receptor 1 (TGF-β RI) protein levels, but not TGF-β RII, in a CD44-dependent manner with concurrent enhancement of the phosphorylated Smad3 (p-Smad3), but not p-Smad2, upon TGF-β1 stimulation. Furthermore, rhHAPLN1 significantly increased sirtuins levels (i.e., SIRT1/2/6) without TGF-β1 and inhibited acetylated p300 levels that were increased by TGF-β1. rhHAPLN1 is crucial in regulating cellular senescence, including p53, p21, and p16, and inflammation markers such as p-NF-κB and Nrf2. Both senile emphysema mouse model induced via intraperitoneal rhHAPLN1 injections and porcine pancreatic elastase (PPE)-induced COPD mouse model generated via rhHAPLN1-containing aerosols inhalations showed a significantly potent efficacy in reducing alveolar spaces enlargement. Preclinical trials are underway to investigate the effects of inhaled rhHAPLN1-containing aerosols on several COPD animal models.

Deciphering the Allosteric Activation Mechanism of SIRT6 Using Molecular Dynamics Simulations

As a member of the histone deacetylase protein family, the NAD+-dependent SIRT6 plays an important role in maintaining genomic stability and regulating cell metabolism. Interestingly, SIRT6 has been found to have a preference for hydrolyzing long-chain fatty acyls relative to deacetylation, and it can be activated by fatty acids. However, the mechanisms by which SIRT6 recognizes different substrates and can be activated by small molecular activators are still not well understood. In this study, we carried out extensive molecular dynamic simulations to shed light on these mechanisms. Our results revealed that the binding of the myristoylated substrate stabilizes the catalytically favorable conformation of NAD+, while the binding of the acetyl-lysine substrate leads to a loose binding of NAD+ in SIRT6. Based on these observations, we proposed a reasonable allosteric binding mode for myristic acid, which can enhance the catalytic activity of SIRT6 by stabilizing the binding of NAD+ with His131 as well as the acetylated substrate. Furthermore, our molecular dynamics simulations demonstrated that synthetic SIRT6 activators, such as UBCS039, MDL-801, and 12q, block the flipping of ribose in NAD+ and therefore can stabilize substrate-NAD+-His131 interactions in a manner similar to fatty acids. In summary, our newly proposed activation mechanism of SIRT6 highlights the importance of protein-substrate interactions, which would facilitate the rational design of new SIRT6 activators.

The Prognostic and Therapeutic Role of Histone Acetylation Modification in LIHC Development and Progression

Background and Objectives: The modification of histone acetylation plays a vital role in regulating tumor occurrence and development, but the interaction between histone acetylation modulator genes and the liver hepatocellular carcinoma (LIHC) microenvironment, as well as immunotherapy, has not been investigated. Materials and Methods: Analysis of all statistical data was carried out using R software (Version 4.2.0) and the online tool Sangerbox. Comprehensive bioinformatics analysis, including signature construction and validation, functional analyses, immune and genomic features analyses, and immunotherapy prediction analyses, were performed to explore the prognostic and therapeutic role of histone acetylation modulator genes in LIHC development and progression. Results: The LIHC cohort from The Cancer Genome Atlas (TCGA) database was selected as the training cohort; the GSE76427 cohort from the Gene Expression Omnibus (GEO) database and the LIRI-JP cohort from the International Cancer Genome Consortium (ICGC) database were selected as the validation cohorts. The histone acetylation modulator gene-based prognostic signature was constructed and validated successfully. Immune infiltration analysis showed that most immune cells and immune functions were enriched in patients with high histone acetylation risk scores (HARS). Additionally, high levels of checkpoint inhibitors (ICIs) and human leukocyte antigens (HLAs) were also observed in high HARS patients. Meanwhile, TIDE algorithm analysis was conducted to explore the relationship between HARS and immunotherapy response, and submap algorithm analysis was used for the verification of the results, from which we found that high HAPS patients were more likely to respond to immunotherapy. Conclusions: Our findings revealed that the histone acetylation modulator genes, particularly for KAT21, SIRT6, and HAT1, may have the potential to function as a new prognostic marker and therapeutic target for LIHC.

A systematic review and meta-analysis of the SIRT1 response to exercise

Sirtuin 1 (SIRT1) is a key physiological regulator of metabolism and a target of therapeutic interventions for cardiometabolic and ageing-related disorders. Determining the factors and possible mechanisms of acute and adaptive SIRT1 response to exercise is essential for optimising exercise interventions aligned to the prevention and onset of disease. Exercise-induced SIRT1 upregulation has been reported in animals, but, to date, data in humans have been inconsistent. This exploratory systematic review and meta-analysis aims to assess various exercise interventions measuring SIRT1 in healthy participants. A total of 34 studies were included in the meta-analysis (13 single bout exercise, 21 training interventions). Studies were grouped according to tissue sample type (blood, muscle), biomarkers (gene expression, protein content, enzyme level, enzyme activity), and exercise protocols. A single bout of high-intensity or fasted exercise per se increases skeletal muscle SIRT1 gene expression as measured by qPCR or RT-PCR, while repeated resistance training alone increases blood SIRT1 levels measured by ELISA. A limited number of studies also show a propensity for an increase in muscle SIRT1 activity as measured by fluorometric or sirtuin activity assay. In conclusion, exercise acutely upregulates muscle SIRT1 gene expression and chronically increases SIRT1 blood enzyme levels.

Targeting impaired nutrient sensing via the sirtuin pathway with novel compounds to prevent or treat dementia: A systematic review

BACKGROUND

Dementia is prevalent in aged populations and is associated with disability and distress for those affected. Therapeutic benefits of drugs targeting dementia are small. Impaired nutrient sensing pathways have been implicated in the pathogenesis of dementia and may offer a novel treatment target.

AIMS

This systematic review collated evidence for novel therapeutic compounds that modify nutrient sensing pathways, particularly the sirtuin pathway, in preventing cognitive decline or improving cognition in normal ageing, mild cognitive impairment (MCI), and dementia.

METHODS

PubMed, Embase and Web of Science databases were searched using key search terms. Articles were screened using Covidence systematic review software. The risk of bias was assessed using the Systematic Review Center for Laboratory animal Experimentation (SYRCLE)'s risk of bias tool for animal studies and Cochrane Risk of Bias tool v 2.0 for human studies.

RESULTS

Out of 3841 articles, 68 were included describing 38 different novel therapeutic compounds that modulate the nutrient sensing pathway via the sirtuin pathway. In animal models (58 studies), all investigated novel therapeutic compounds showed cognitive benefits. Ten studies were human intervention trials targeting normal ageing (1 study) and dementia populations (9 studies). Direct sirtuin (silent mating type information regulation 2 homolog) 1 (SIRT1) activators Resveratrol and Nicotinamide derivatives improved cognitive outcomes among human subjects with normal cognition and MCI.

CONCLUSION

Animal studies support that modulation of the sirtuin pathway has the potential to improve cognitive outcomes. Overall, there is a clear lack of translation from animal models to human populations.

SIRT6 reduces the symptoms of premature ovarian failure and alleviates oxidative stress and apoptosis in granulosa cells by degrading p66SHC via H3K9AC

CONTEXT

Substantial evidence suggests that ovarian oxidative stress can result in severe ovarian dysfunction.

OBJECTIVE

The purpose of this article is to investigate the potential of SIRT6 in alleviating premature ovarian failure (POF) by inhibiting oxidative stress.

METHODS

To mimic POF, mice were administered daily subcutaneous injections of d-galactose. The levels of E2, FSH, LH, AMH, and progesterone in serum were measured, along with changes in follicles and SIRT6 levels. Mice were treated with the SIRT6 agonist MDL-800, SIRT6 levels, follicles, and aforementioned hormones were reassessed. The effects of MDL-800 on oxidative stress and apoptosis were subsequently identified. Primary granulosa cells were isolated from mice, and the effects of H2O2 and MDL-800 on cell viability, oxidative stress, SIRT6 level, and apoptosis were evaluated. In addition, the regulation of SIRT6 on H3K9AC/p66SHC was verified by examining changes in protein levels, promoter activity, and the reversal effects of p66SHC overexpression.

RESULTS

MDL-800 mitigated hormone fluctuations, reduced follicle depletion in ovarian tissue, and attenuated oxidative stress and apoptosis in mice. In vitro experiments demonstrated that MDL-800 enhanced the resilience of primary granulosa cells against H2O2, as evidenced by increased cell viability and reduced oxidative stress and apoptosis. Furthermore, SIRT6 was found to decrease H3K9AC and p66SHC levels, as well as attenuate p66SHC promoter activity. The protective effects of MDL-800 on cells were reversed upon p66SHC overexpression.

CONCLUSION

In summary, this study highlights that activation of SIRT6 can alleviate POF and reduce oxidative stress by degrading H3K9AC and suppressing p66Shc levels in granulosa cells.

AI-Powered Virtual Screening of Large Compound Libraries Leads to the Discovery of Novel Inhibitors of Sirtuin-1

The discovery of new scaffolds and chemotypes via high-throughput screening is tedious and resource intensive. Yet, there are millions of small molecules commercially available, rendering comprehensive in vitro tests intractable. We show how smart algorithms reduce large screening collections to target-specific sets of just a few hundred small molecules, allowing for a much faster and more cost-effective hit discovery process. We showcase the application of this virtual screening strategy by preselecting 434 compounds for Sirtuin-1 inhibition from a library of 2.6 million compounds, corresponding to 0.02% of the original library. Multistage in vitro validation ultimately confirmed nine chemically novel inhibitors. When compared to a competitive benchmark study for Sirtuin-1, our method shows a 12-fold higher hit rate. The results demonstrate how AI-driven preselection from large screening libraries allows for a massive reduction in the number of small molecules to be tested in vitro while still retaining a large number of hits.

Sirtuins: Promising Therapeutic Targets to Treat Ischemic Stroke

Stroke is a major cause of mortality and disability globally, with ischemic stroke (IS) accounting for over 80% of all stroke cases. The pathological process of IS involves numerous signal molecules, among which are the highly conserved nicotinamide adenine dinucleotide (NAD+)-dependent enzymes known as sirtuins (SIRTs). SIRTs modulate various biological processes, including cell differentiation, energy metabolism, DNA repair, inflammation, and oxidative stress. Importantly, several studies have reported a correlation between SIRTs and IS. This review introduces the general aspects of SIRTs, including their distribution, subcellular location, enzyme activity, and substrate. We also discuss their regulatory roles and potential mechanisms in IS. Finally, we describe the current therapeutic methods based on SIRTs, such as pharmacotherapy, non-pharmacological therapeutic/rehabilitative interventions, epigenetic regulators, potential molecules, and stem cell-derived exosome therapy. The data collected in this study will potentially contribute to both clinical and fundamental research on SIRTs, geared towards developing effective therapeutic candidates for future treatment of IS.

Exploring the Influence of Age, Gender and Body Mass Index on Colorectal Cancer Location

Background and objectives: The global burden of non-communicable diseases like obesity and cancer, particularly colorectal cancer (CRC), is increasing. The present study aimed to investigate the association between CRC location (proximal vs. distal) and patient demographic factors including age, sex, and BMI, as well as cancer stage at diagnosis. Materials and Methods: In this cross-sectional study, data from 830 patients diagnosed with CRC were analyzed. The variables included age, sex, weight, height, BMI, cancer location, and cancer stage at diagnosis. Patients were stratified into three age groups and three BMI categories, and we analyzed the association between cancer location and these variables using Chi-squared tests and multivariate logistic regression. Results: The rectum and ascending colon were the most common locations of malignant neoplasms. No statistically significant differences in cancer location across age groups were observed. Significant differences were found in the BMI across age groups, particularly in the normal weight and overweight categories. Normal weight and obese patients had a higher proportion of Stage 3 and Stage 4 cancers. Obesity emerged as a significant predictor for rectal cancer in a multivariate logistic regression analysis, with an odds ratio of 1.56. However, no significant associations were found between cancer location and other factors like age, gender, or cancer stage. Conclusions: Our study revealed that normal weight and obese patients had a higher proportion of Stage 3 and Stage 4 cancers, with obesity emerging as a significant predictor for rectal cancer. It is important to note that while obesity was found to be a significant predictor for rectal cancer, the development and location of colorectal cancer is likely influenced by various factors beyond those studied here. Therefore, further research is needed to investigate the roles of other potential risk factors, like loss of SIRT6 and adipose tissue homeostasis. Additionally, inflammation associated with microbiota in the colorectal mucosa, systemic gene expression, and visceral obesity may also play important roles in the development and progression of colorectal cancer. Understanding these intricate relationships is crucial for better screening, disease prognosis, and management strategies.

ADENOSINE MONOPHOSPHATE-ACTIVATED PROTEIN KINASE PHOSPHORYLATION MEDIATED BY SIRTUIN 5 ALLEVIATES SEPTIC ACUTE KIDNEY INJURY

ABSTRACT

Background : Our previous studies have shown that ameliorating mitochondrial damage in renal tubular epithelial cells (RTECs) can alleviate septic acute kidney injury (SAKI). It is reported that AMPK phosphorylation (p-AMPK) could ameliorate mitochondrial damage in renal tissue and Sirtuin 5 (SIRT5) overexpression significantly enhanced the level of p-AMPK in bovine preadipocytes. However, the role of SIRT5-mediated phosphorylation of AMPK in SAKI needs to be clarified. Methods : WT/SIRT5 gene knockout mouse model of cecal ligation and puncture-induced SAKI and a human kidney 2 cell model of LPS-induced SAKI were constructed. An AMPK chemical activator and SIRT5 overexpression plasmid were used. Indexes of mitochondrial structure and function, level of p-AMPK, and expression of SIRT5 protein in renal tissue and RTECs were measured. Results : After sepsis stimulation, the p-AMPK level was decreased, mitochondrial structure was disrupted, and ATP content was decreased. Notably, an AMPK activator alleviated SAKI. Sirtuin 5 gene knockout significantly aggravated SAKI, while SIRT5 overexpression alleviated mitochondrial dysfunction after LPS stimulation, as manifested by the increase of p-AMPK level, the alleviation of mitochondrial structure damage, the restoration of ATP content, the decrease of proapoptotic protein expression, as well as the reduction of reactive oxygen species generation. Conclusions : Upregulation of SIRT5 expression can attenuate mitochondrial dysfunction in RTECs and alleviate SAKI by enhancing the phosphorylation of AMPK.

microRNA-29b-3p/sirtuin-1/peroxisome proliferator-activated receptor γ suppress osteogenic differentiation

Osteoporosis is described as an age-associated impairment of bone formation. microRNA (miR)-29b-3p was thought to be linked to osteoblast differentiation; however, the underlying molecular pathways are yet unknown. The study's goal was to look into the involvement of miR-29b-3p in osteoporosis and the pathophysiological mechanisms. A murine model of estrogen deficiency-induced bone loss was established to simulate postmenopausal osteoporosis. Reverse transcription-quantitative PCR (RT-qPCR) was performed to assess the level of miR-29b-3p of bone tissue. Additionally, miR-29b-3p/sirtuin-1 (SIRT1)/peroxisome proliferator-activated receptor γ (PPARγ) axis in the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) was examined. Osteogenesis-related markers, including alkaline phosphatase (ALP), osteocalcin (OCN), and runt-related transcription factor 2 (RUNX2), were assessed at protein and molecular levels. ALP staining and Alizarin Red staining were used to detect ALP activity and calcium deposition. The ovariectomy group was shown to express miR-29b-3p at higher levels in vitro, and miR-29b-3p mimics suppressed osteogenic differentiation and protein/mRNA expression levels of osteogenesis-related markers in vivo. SIRT1 was identified as a target of miR-29b-3p using luciferase reporter assays. Overexpression of SIRT1 reduced the inhibition of osteogenic differentiation by miR-29b-3p. Rosiglitazone, an activator of PPARγ signaling, was able to reverse the downregulation of the osteogenic differentiation of BMSCs and the protein expression of PPARγ caused by miR-29b-3p inhibitors. The results revealed that osteogenesis was suppressed by miR-29b-3p, which blocks the SIRT1/PPARγ axis. These results suggested that postmenopausal osteoporosis could be treated by targeting miR-29b-3p SIRT1/PPARγ.

Thymoquinone and quercetin protect against hepatic steatosis in association with SIRT1/AMPK stimulation and regulation of autophagy, perilipin-2, and cytosolic lipases

BACKGROUND

We sought to investigate thymoquinone (TQ)/quercetin combination in preventing hepatic steatosis (HS).

MATERIALS AND METHODS

The included rat groups; (1) Control, (2) HS model, (3) HS treated with TQ 10 mg.kg^-1.d^-1, (4) HS treated with quercetin 50 mg.kg^-1.d^-1, and (5) HS treated with both compounds for 4 weeks.

RESULTS

TQ/quercetin co-treatment augmented the anti-steatosis potential of each ingredient. The results revealed more (p < 0.001) sirtuin (SIRT1)/AMP-activated protein kinase (p-AMPK) upregulation compared to each treatment in line with autophagy protein Atg7 enhancement, and suppressed pro-inflammatory and oxidation markers. They diminished the hepatic lipogenic enzymes and perilipin-2 and activated the cytosolic lipases adipose triglyceride lipase (ATGL). Histological and Biochemical analysis revealed diminished lipid deposition and improved liver enzymes (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) compared to the data of separate treatments.

CONCLUSION

TQ and quercitin effectively upregulated SIRT1/p-AMPK and regulated hepatic perilipin-2/ATGL, inflammation and oxidative stress, preserved liver structure and function. TQ/quercetin combination additively prevents HS.