Sirtuin Research Articles

Cardioprotective effect of 19,20-epoxydocosapentaenoic acid (19,20-EDP) in ischemic injury involves direct activation of mitochondrial sirtuin 3.

Although current clinical therapies following myocardial infarction have improved patient outcomes, morbidity, and mortality rates secondary to ischemic and ischemia reperfusion (IR) injury remains high. Maintaining mitochondrial quality is essential to limit myocardial damage following cardiac ischemia and IR injury. The mitochondrial deacetylase sirtuin 3 (SIRT3) plays a pivotal role in regulating mitochondrial function and cardiac energy metabolism. In the current study, we hypothesize that 19,20-epoxydocosapentaenoic acid (19,20-EDP) attenuates cardiac IR injury via stimulating mitochondrial SIRT3. Ex vivo models of isolated heart perfusions were performed in C57BL/6 mice to assess the effect of 19,20-EDP on cardiac function and energy metabolism following IR injury. In vivo permanent occlusion of the left anterior descending coronary artery (LAD) was performed to induce myocardial infarction (MI), mice were administered 19,20-EDP with or without the SIRT3 selective inhibitor 3-TYP. Mitochondrial SIRT3 targets and respiration were assessed in human left ventricular (LV) tissues obtained from individuals with ischemic heart disease (IHD) and compared to non-failing controls (NFC). Binding affinity of 19,20-EDP to human SIRT3 was assessed using molecular modeling and fluorescence thermal shift assay. Results demonstrated hearts treated with 19,20-EDP had improved post-ischemic cardiac function, better glucose oxidation rates and enhanced cardiac efficiency. The cardioprotective effects were associated with enhanced mitochondrial SIRT3 activity. Interestingly, treatment with 19,20-EDP markedly improved mitochondrial respiration and SIRT3 activity in human left ventricle (LV) fibers with IHD compared to NFC. Moreover, 19,20-EDP was found to bind to the human SIRT3 protein enhancing the NAD+ -complex stabilization leading to improved SIRT3 activity. Importantly, the beneficial effects of 19,20-EDP were abolished by SIRT3 inhibition or using the S149A mutant SIRT3. These data demonstrate that 19,20-EDP-mediated cardioprotective mechanisms against ischemia and IR injury involve mitochondrial SIRT3, resulting in improved cardiac efficiency.

Neuroprotective Potential of Aminonaphthoquinone Derivatives Against Amyloid Beta-Induced Neuronal Cell Death Through Modulation of SIRT1 and BACE1

Alzheimer’s disease (AD) is characterized by the accumulation of tau protein tangles and amyloid-β (Aβ) plaques in the central nervous system (CNS), leading to progressive neurodegeneration. Hence, the discovery of disease-modifying agents capable of delaying the progression is essential for effective management. Aminonaphthoquinone (ANQ) is an attractive pharmacophore with various biological effects. This study explores the neuroprotective potentials of ANQ derivatives (1–18) using in vitro models of AD pathology (i.e., Aβ42-induced SH-SY5Y cells). Findings demonstrated that all compounds mitigated Aβ42-induced cellular damage by preserving cell viability and morphology. Among all, four compounds (10, 12, 16, and 18) showed potent antioxidant activities as well as abilities to minimize AD-related damages (i.e. decreasing intracellular reactive oxygen species (ROS) production, preserving mitochondrial membrane potential (MMP), protecting membrane damage, and modulating beta-secretase 1 (BACE1) activity) with comparable protective effects to the well-known neuroprotectant, resveratrol (RSV). A molecular docking study indicated these compounds could suitably bind to sirtuin 1 (SIRT1) protein with preferable affinity. Key amino acid residues and key functional groups essential for binding interactions were revealed. Target prediction identified a list of possible AD-related targets of these compounds offering insights into their mechanisms of action and suggesting their multifunctional potentials. Additionally, in silico predictions revealed that these candidates showed favorable drug-like properties. Overall, this study highlighted the therapeutic potential of ANQ derivatives in AD treatment, emphasizing the need for further experimental validation and comprehensive investigations to fully realize their therapeutic benefits.

SIRT1 Activation Suppresses Corneal Endothelial–Mesenchymal Transition via the TGF-β/Smad2/3 Pathway

Endothelial–mesenchymal transition (EnMT) is the transversion of endothelial cells to mesenchymal cells under certain physiological or pathological conditions. When EnMT occurs in the corneal endothelium, corneal endothelial cells (CECs) lose their normal function and thus cannot maintain corneal clarity. Studies have shown that the mechanism of EnMT in CECs involves the transforming growth factor-β (TGF-β) signaling pathway, and one of the important inhibitors of the TGF-β/Smad2/3 pathway is sirtuin-1 (SIRT1). In this study, we used a rat model of corneal endothelium injury and TGF-β1-treated human CECs to induce EnMT, aiming to explore whether SIRT1 activation inhibits corneal EnMT in vivo and in vitro. SIRT1 was activated and suppressed using resveratrol (RSV) and EX527, respectively. The endothelial markers and mesenchymal markers were measured by immunofluorescence and Western blot assays. Co-immunoprecipitation was used to detect the interaction between SIRT1 and Smad2/3. The results showed that after mechanical injury, the group treated with RSV-activated SIRT1 regained corneal transparency and recovered from edema faster than the control group. Moreover, RSV-activated SIRT1 downregulated the expression levels of alpha smooth muscle actin (α-SMA), vimentin, and Snail and upregulated the expression levels of E-cadherin and Na+/K+-ATPase both in vivo and in vitro, but these effects were reversed when SIRT1 was inhibited by EX527. SIRT1 also upregulated the expression levels of TGF-β receptor 1 and phosphorylated Smad2/3. The interaction between SIRT1 and Smad2/3 in vitro was confirmed by co-immunoprecipitation. Overall, our results indicate that SIRT1 activation inhibits corneal EnMT via the TGF-β/Smad2/3 pathway, which may be a potential therapeutic target for corneal endothelium dysfunction.

SIRT2 Mediated Microtubule Acetylation in Osteogenic Differentiation.

To assess the role of microtubule acetylation in the transportation of amorphous calcium phosphate (ACP)-containing vesicles that mediate the osteogenic differentiation process of rat bone mesenchymal stem cells (BMSCs). Rat BMSCs were cultured and transfected with sirtuin 2 (SIRT2) overexpression plasmids for an in vitro model. The microtubule acetylation-related protein levels were detected by western blots. The microtubule acetylation and the secretion rate of extracellular ACPcontaining vesicles were observed with immunofluorescence and live cell fluorescence imaging. The secretion of ACP was observed by transmission electron microscopy. The mineralised nodule formation was stained with Alizarin Red S staining and observed by microscopy. Microtubule acetylation was increased during osteogenic differentiation of BMSCs, and microtubule transport efficiency was enhanced. Mechanically, microtubule acetylation is the key reason for the increased transportation rate of ACP-containing vesicles and enhanced osteogenic differentiation, as both were blocked after SIRT2-mediated microtubule acetylation inhibition. Microtubule acetylation mainly promotes the transportation and secretion of ACP vesicles, and ultimately promotes the osteogenic differentiation process.

SGK1-Mediated Vascular Smooth Muscle Cell Phenotypic Transformation Promotes Thoracic Aortic Dissection Progression.

The occurrence of thoracic aortic dissection (TAD) is closely related to the transformation of vascular smooth muscle cells (VSMCs) from a contractile to a synthetic phenotype. The role of SGK1 (serum- and glucocorticoid-regulated kinase 1) in VSMC phenotypic transformation and TAD occurrence is unclear. Four-week-old male Sgk1F/F (Sgk1 floxed) and Sgk1F/F;TaglnCre (smooth muscle cell-specific Sgk1 knockout) mice were administered β-aminopropionitrile monofumarate for 4 weeks to model TAD. The SGK1 inhibitor GSK650394 was administered daily via intraperitoneal injection to treat the mouse model of TAD. Immunopurification and mass spectrometry were used to identify proteins that interact with SGK1. Immunoprecipitation, immunofluorescence colocalization, and GST (glutathione S-transferase) pull-down were used to detect molecular interactions between SGK1 and SIRT6 (sirtuin 6). RNA-sequencing analysis was performed to evaluate changes in the SIRT6 transcriptome. Quantitative chromatin immunoprecipitation was used to determine the target genes regulated by SIRT6. Functional experiments were also conducted to investigate the role of SGK1-SIRT6-MMP9 (matrix metalloproteinase 9) in VSMC phenotypic transformation. The effect of SGK1 regulation on target genes was evaluated in human and mouse TAD samples. Sgk1F/F;TaglnCre or pharmacological blockade of Sgk1 inhibited the formation and rupture of β-aminopropionitrile monofumarate-induced TADs in mice and reduced the degradation of the ECM (extracellular matrix) in vessels. Mechanistically, SGK1 promoted the ubiquitination and degradation of SIRT6 by phosphorylating SIRT6 at Ser338, thereby reducing the expression of the SIRT6 protein. Furthermore, SIRT6 transcriptionally inhibits the expression of MMP9 through epigenetic modification, forming the SGK1-SIRT6-MMP9 regulatory axis, which participates in the ECM signaling pathway. Additionally, our data showed that the lack of SGK1-mediated inhibition of ECM degradation and VSMC phenotypic transformation is partially dependent on the regulatory effect of SIRT6-MMP9. These findings highlight the key role of SGK1 in the pathogenesis of TAD. A lack of SGK1 inhibits VSMC phenotypic transformation by regulating the SIRT6-MMP9 axis, providing insights into potential epigenetic strategies for TAD treatment.

Characterization of tea polysaccharides from Tieguanyin oolong tea and their hepatoprotective effects via AMP-activated protein kinase-mediated signaling pathways.

In the present study, we succeeded in extracting tea polysaccharide (TPS) from Tieguanyin oolong tea, and the TPS was characterized. TPS is an acidic heteropolysaccharide containing rhamnose, arabinose, galactose, glucose (Glc), xylose, mannose, galacturonic acid, and guluronic acid. We found that TPS supplementation partially reversed the elevated levels of serum alanine aminotransferase, total cholesterol, and low-density lipoprotein cholesterol in high-fat diet (HD)-induced nonalcoholic fatty liver disease (NAFLD) mice (p<0.05), and hepatic steatosis and impaired Glc tolerance were also ameliorated. After HD intervention, the activity of Adenosine 5'-monophosphate-activated protein kinase (AMPK) and its downstream genes, including Sirtuin 1 (SIRT1), sterol regulatory element-binding protein-1c (SREBP1c), acetyl-coenzyme A carboxylase 1 (ACC1), and adipose triglyceride lipase (ATGL), was significantly inhibited (p<0.05). TPS can increase the expression of these genes. The hepatoprotective effects of TPS in AMPK-/- mice almost completely disappeared. Moreover, the expression levels of SIRT1, SREBP1c, ACC1, and ATGL did not significantly change after TPS supplementation (p>0.05). Therefore, our findings suggest that TPS protects the liver from hepatic glucolipid metabolism disorders in HD-induced NAFLD mice by activating AMPK-mediated signaling pathways.

BEX4 inhibits the progression of clear cell renal cell carcinoma by stabilizing SH2D4A, which is achieved by blocking SIRT2 activity.

Clear cell renal cell carcinoma (ccRCC) is one of the most common malignancies. Recently, the role of brain-expressed X-linked 4 (BEX4) in cancer progression has received increasing attention. This study aimed to investigate the function of BEX4 in ccRCC and to reveal the underlying mechanisms. We first confirmed that BEX4 was significantly downregulated in ccRCC by bioinformatics analysis and that patients with low BEX4 expression tended to have prolonged overall survival time. Subsequently, we confirmed that BEX4 inhibited ccRCC cell proliferation in vitro and tumorigenesis in vivo through a series of cell function assays and the establishment of a nude mouse xenograft model, respectively. Mechanistically, we found that BEX4 positively regulates the expression of Src homology 2 domain-containing 4A (SH2D4A), an inhibitor of the NOTCH pathway, which further promoted the tumor-suppressive effects of BEX4. In addition, our study confirmed that the promoting effect of BEX4 on SH2D4A was achieved by inhibiting the deacetylase sirtuin 2 (SIRT2) activity. On this basis, we found that there was a competition between acetylation and ubiquitination modifications at the K69 site of SH2DA4 and that BEX4-induced upregulation of acetylation at the k69 site stabilizes SH2D4A protein expression by inhibiting ubiquitination at the same site. In addition, dual-luciferase assays showed that the transcriptional activity of BEX4 was positively regulated by activation transcription factor 3 (ATF3). Our study suggests that BEX4 plays a role in inhibiting tumor progression in ccRCC and maybe a new diagnostic and therapeutic target for ccRCC patients.

High glucose potentiates Zika virus induced-astroglial dysfunctions.

Zika virus (ZIKV) is a neurotropic flavivirus that induces congenital Zika syndrome and neurodevelopmental disorders. Given that ZIKV can infect and replicate in neural cells, neurological complications in adult brain are also observed. Glial cells may emerge to delay and/or prevent the development of ZIKV-induced neurodegeneration. These cells actively participate in metabolic, inflammatory and redox processes, and consequently, in the pathophysiology of neurodegenerative diseases, including diabetic encephalopathy. In this sense, changes in glucose metabolism can support the inflammatory activity of astroglial cells; however, the effects of increased glucose concentration during ZIKV infection have not yet been explored in astroglial cells. Here, we evaluated functional parameters of astroglial cells exposed to ZIKV upon normal and high glucose concentrations, focusing on inflammatory profile, oxidative stress, and expression of critical genes for astroglial functions. High glucose potentiated the pro-inflammatory and oxidative effects of ZIKV, as well as potentiated the downregulation of signaling pathways, such as Nrf-2 (nuclear factor erythroid derived 2 like 2), sirtuin 1 (SIRT1), peroxisome proliferator activated receptor gamma coactivator 1-alpha (PGC-1α), and poly (ADP-ribose) polymerase (PARP). In summary, our results suggest that high glucose can favor the activation of inflammatory signaling while impairing cytoprotective pathways in astroglial cells exposed to ZIKV and reinforce the hypothesis that this virus is highly neurotrophic, with significant impact in glial cells.

Circ-TTC17 Promotes Esophagus Squamous Cell Carcinoma Cell Growth, Metastasis, and Inhibits Autophagy-Mediated Radiosensitivity Through miR-145-5p/SIRT1 Axis.

Circular RNA (circRNA) plays a significant role in esophagus squamous cell carcinoma (ESCC) progression. Nevertheless, circ-TTC17 roles in ESCC have not fully understood. The levels of circ-TTC17, miR-145-5p and sirtuin 1 (SIRT1) were determined using qRT-PCR. ESCC cell functions were examined by CCK8 assay, flow cytometry, transwell assay and colony formation assay. The relative protein levels of autophagy marker and SIRT1 were determined by western blot (WB). The interactions among circ-TTC17, miR-145-5p, and SIRT1 were verified by dual-luciferase reporter assay and RIP assay. circ-TTC17 was overexpressed and miR-145-5p was underexpressed in ESCC. circ-TTC17 knockdown restrained ESCC cell proliferation and metastasis, while enhance apoptosis and autophagy-mediated radiosensitivity. Circ-TTC17 could sponge miR-145-5p, and its inhibitor reversed the inhibitory effect of circ-TTC17 knockdown on ESCC cell progression. Additionally, SIRT1 was targeted by miR-145-5p, and SIRT1 overexpression abolished miR-145-5p-mediated the suppressive effect on ESCC cell progression. Also, circ-TTC17 interference reduced ESCC tumor growth via miR-145-5p/SIRT1 axis. circ-TTC17 promoted ESCC cell growth, metastasis and inhibited autophagy-mediated radiosensitivity by miR-145-5p/SIRT1 axis.

MiR-148b Caused Liver Injury in Rats with Traumatic Hemorrhagic Shock by Inhibiting SIRT6 Expression.

The purpose of this study was to investigate the role of miR- 148b in liver injury in rats with traumatic hemorrhagic shock (THS) and to elucidate its potential mechanism. The levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the serum of rats were detected by enzyme-linked immune sorbent assay (ELISA), and the injury of rat liver was analyzed by hematoxylin-eosin (H&E) staining. Apoptosis of rat hepatocytes and normal rat liver cell line (BRL3A) was identified by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) assay and flow cytometry, respectively. MiR-148b and sirtuin 6 (SIRT6) expression was measured by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot. Lactate dehydrogenase (LDH) content and cell viability were measured by commercial kits and cell counting kit-8 (CCK-8) assay, respectively. The binding sites of miR-148b and SIRT6 were predicted by the Starbase database and verified by dual luciferase reporter assay. MiR-148b expression in THS rats or ischemia-reperfusion (I/R)-treated cells was higher than in the control group. Overexpression of miR-148b further promoted the effects of I/R, which enhanced the levels of ALT, AST and LDH, cell apoptosis of liver tissue or BRL3A cells and decreased the expression of SITR6. Besides, miR-148b negatively correlated with SIRT6, and upregulated the expression of SIRT6 could partly reverse the effect of miR-148b. Hepatocyte injury induced by I/R was achieved by regulating miR-148b /SIRT6 axis.

Costunolide ameliorates rotenone-induced Parkinson's disease in rat model via activation of SIRT-1/p-AMPK cascade and suppression of IL-6/STAT3 axis

Costunolide (COST), a sesquiterpene lactone, has demonstrated promising potential in molecular docking studies targeting key proteins associated with Parkinson's disease (PD), particularly AMP-activated protein kinase (AMPK) and sirtuin-1 (SIRT1). Building on these preliminary findings, this study was designed to explore the in vivo neuroprotective effects of COST in a rotenone-induced PD model, aiming to substantiate its therapeutic efficacy. The evaluation focused on motor function, oxidative stress markers, neuroinflammatory indicators, and the balance between autophagy and apoptosis, alongside histopathological examination.Treatment with COST displayed an enhancement in motor performance, as observed by improved results in both the open-field and narrow beam walk tests. Concurrently, COST preserved dopaminergic neurons in the substantia nigra and boosted tyrosine hydroxylase immunoreactivity. Furthermore, COST reduced oxidative stress status via increasing SIRT-1 and PGC-1α content. Notably, COST suppressed neuroinflammation by inhibiting the IL-6R/STAT3/NFκBp65 /IL-6 signaling pathway. Additionally, COST stimulated autophagy via the activation of p-AMPK/ULK1/Beclin-1 cascade, facilitating the removal misfolded protein, α-synuclein. COST also reduced apoptosis by increasing Bcl-2 and decreasing Bax levels. In conclusion, COST exhibited promising neuroprotective effects against rotenone-induced PD in a rat model. This protection is mediated through the activation of the SIRT1/PGC-1α and p-AMPK/ULK1/Beclin-1 pathways, alongside the inhibition of the IL-6R/STAT3/NFκBp65 axis. Collectively, these mechanisms attenuated oxidative stress and neuroinflammation while restoring the balance between apoptosis and autophagy, positioning COST as a potential therapeutic candidate for Parkinson's disease.

2-hydroxy-3-methyl anthraquinone promotes apoptosis and inhibits invasion of human hepatocellular carcinoma cells by targeting nicotinamide adenine dinucleotide-dependent protein deacetylase sirtuin-1/cellular tumor antigen p53 signaling pathway.

To investigate the anti-liver cancer effect of 2-hydroxy-3-methyl anthraquinone (HMA) and the specific mechanism based on nicotinamide adenine dinucleotide-dependent protein deacetylase sirtuin-1 (SIRT1)/cellular tumor antigen p53 (p53) pathway. Cell counting kit-8 method was used to observe the effect of HMA on the activity of human hepatocellular carcinoma cells (HepG2) cells. At 72 h and 80 μL HMA, the apoptosis rate of HepG2 cells in each group was measured by flow cytometry. Transwell was used to assay for cell invasion. The protein expression levels of SIRT1, p53, B-cell lymphoma-2 (Bcl-2), Bcl-2 associated X protein (Bax), caspase-9 (CASP9) and caspase-3 (CASP3) were detected by Western Blot. HMA significantly inhibited the proliferation of HepG2 cells, The half inhibiting concentration (IC50) of the HMA at 24, 48 and 72 h were examined and it were 126.3, 98.6, and 80.55 μM, respectively. Compared with the control group, the apoptosis rate of HMA, Selisistat (EX527), and HMA+ EX527 groups enhanced, while the apoptosis rate of SRT1720 diminished, demonstrating that inhibition of SIRT1 can lead to apoptosis of HepG2 cells. HMA+ EX527 group had the highest apoptosis rate, the lowest expression of SIRT1 and Bcl-2, and the highest expression of p53, Bax, CASP9 and CASP3. The number of invasions of HepG2 was significantly reduced after HMA and EX527 intervened. Western blot shows HMA could inhibit SIRT1, promote the expression of p53, and decrease the ratio of Bcl-2/Bax. HMA induced apoptosis in HepG2 cells, while inhibiting proliferation and invasion. The mechanism of HMA against HCC may be related to the SIRT1/p53 pathway.

Angong Niuhuang Pill pretreatment alleviates cerebral ischemia-reperfusion injury by inhibiting excessive autophagy through the SIRT1-H4K16ac axis

Ethnopharmacological relevanceCerebral ischemia-reperfusion injury (CIRI) is an important pathological process in stroke treatment. Angong Niuhuang Pill (ANP), originating from Wenbing Tiaobian, has been shown to have neuroprotective effects, but its mechanism in alleviating CIRI remains unclear. Aim of the studyThis study aimed to elucidate the mechanism by which ANP alleviates CIRI using acetylomics and proteomics. Materials and methodsThe CIRI model was established using middle cerebral artery occlusion (MCAO). Neurological deficit scoring, TTC staining, regional cerebral blood flow (rCBF) measurement, and TUNEL staining were used to assess the neuroprotective effects of ANP pretreatment on CIRI. Acetylomics and proteomics analyses were performed to identify the potential mechanisms by which ANP reduces CIRI. Finally, the role of SIRT1-H4K16ac-mediated autophagy in the neuroprotective effects of ANP was validated by using a SIRT1 inhibitor, EX527. ResultsANP pretreatment markedly lowered neurological deficit scores and cerebral infarct volumes, increased rCBF, and reduced apoptosis. Acetylomics and proteomics results suggested that ANP regulated autophagy at the transcriptional level by modulating H4K16ac. Immunofluorescence and western blot analyses confirmed that ANP promoted the accumulation of sirtuin 1 (SIRT1). Specifically, ANP pretreatment reduced H4K16ac levels, decreased LC3B-II/I ratios, upregulated SQSTM1/p62, and suppressed the expression of ATG5 and ATG7. The ability of EX527 to counteract these effects underscored the importance of the SIRT1-H4K16ac pathway in mediating the protective action of ANP against CIRI. ConclusionsANP provides neuroprotection by modulating the SIRT1-H4K16ac pathway, thereby preventing the excessive autophagy triggered by CIRI.

Stem cell factor-mediated upregulation of SIRT1 protects melanin-deprived keratinocytes against UV-induced DNA damage in individuals with vitiligo.

Despite the loss of melanocytes, individuals with vitiligo have a significantly lower risk of developing skin malignancies compared to ethnicity-matched controls. The study investigated the molecular mechanisms that protect skin cells (keratinocytes) from UV-B-induced DNA damage in individuals with vitiligo. The study found that upregulation of stem cell factor (SCF) signaling significantly reduced γ-H2AX positivity and cyclobutane pyrimidine dimer formation and improved mitochondrial health (elongated mitochondria, reduced reactive oxygen species [ROS] and lipid peroxidation) in keratinocytes upon UV-B exposure. Interestingly, SCF treatment also reduced lipid droplet accumulation and triacylglyceride levels by upregulating lipoprotein lipase (LPL). Further, siLPL increased DNA damage and lipid droplet (LD) accumulation, while NO-1886, an LPL agonist, reversed both, suggesting a direct link between lipid metabolism and DNA damage. Downregulation of NAD-dependent deacetylase sirtuin1 (SIRT1) with siRNA or with Ex-527, a pharmacological inhibitor of SIRT1, diminished the protective effects mediated by SCF and NO-1886, suggesting SIRT1 to be the final effector protein in the SCF-LPL-SIRT1 signaling axis. Analysis of clinical samples of vitiligo corroborated the upregulation of SCF and LPL in lesional epidermis. In conclusion, our study demonstrates a novel SCF-LPL-SIRT1 signaling axis that confers protection to vitiligo keratinocytes from the harmful effects of UV-B radiation.

The protein composition of human adenovirus replication compartments.

Human adenoviruses are double-stranded DNA viruses that replicate in the cell nucleus and induce the formation of replication compartments (RCs) that are critical in viral replication and control of virus-host interactions. RCs are specialized virus-induced subnuclear microenvironments where not only viral genome replication and expression are orchestrated but also host proteins that restrict viral replication are co-opted and subverted. The protein composition of these RCs remains largely unexplored. In this study, we isolated adenovirus RC-enriched fractions from infected cells at different times post-infection and employed a tandem mass tag-based quantitative mass spectrometry approach to identify proteins associated with RCs (data available via ProteomeXchange identifier PXD051745). These findings reveal an elaborate network of host and viral proteins potentially relevant for RC formation and function. To validate the RC-protein components identified by mass spectrometry, we employed immunofluorescence and immunoblotting techniques. Proteins previously described to colocalize in RCs in infected cells were identified in the isolated subnuclear fractions. In addition, we validated newly identified proteins associated with RCs, including the high mobility group box 1 (HMGB1), the SET nuclear proto-oncogene, the structure-specific recognition protein 1 (SSRP1), the CCCTC-binding protein (CTCF), and sirtuin 6 (SIRT6). We identified HMGB1 as a protein that binds to the viral DNA binding protein (DBP). Using shRNA knockdowns and inhibitors, we demonstrated that HMGB1 acts as a proviral factor, promoting efficient viral DNA synthesis and progeny production. Our data further suggest potential candidate targets for therapeutic intervention and provide mechanistic insights into the molecular basis of virus-host interactions.IMPORTANCEHuman adenoviruses serve as models for studying respiratory viruses and have provided critical insights into viral genome replication and gene expression, as well as the control of virus-host interactions. These processes are coordinated within virus-induced subnuclear microenvironments known as RCs. We conducted quantitative proteome analyses of RC-enriched subnuclear fractions at different times post-infection with human adenovirus species C type 5, revealing a multifaceted network of proteins that participate in the regulation of gene expression, DNA damage response, RNA metabolism, innate immunity, and other cellular antiviral defense mechanisms. Furthermore, we validated the localization of several host proteins to viral RCs using immunofluorescence microscopy and immunoblotting and identified cellular HMGB1 as a proviral factor late during infection. These findings represent the first analysis of the proteomes of isolated RCs and not only enhance our understanding of nuclear organization during infection but also shed light on the complex interplay between viral and host factors within RCs.

Dapagliflozin and Sirtuin-1 interaction and mechanism for ameliorating atrial fibrillation in a streptozotocin-induced rodent diabetic model.

The incidence of atrial fibrillation (AF) increases with age and is particularly high in individuals with diabetes. Sodium-glucose cotransporter-2 inhibitors (SGLT2i), such as dapagliflozin, show promise in treating heart failure (HF) and reducing the risk of AF. Sirtuin 1 (SIRT1), a key enzyme in metabolic regulation, may be influenced by SGLT2i and play a role in the development of AF. This study investigates the relationship between dapagliflozin therapy and atrial tachyarrhythmia in diabetic cardiomyopathy, with a focus on the role of SIRT1. A streptozotocin (STZ)-induced diabetes mellitus (DM) rat model was used to assess AF across four groups: sham, STZ, STZ with dapagliflozin, and STZ with dapagliflozin + sirtinol (a SIRT1 inhibitor). Additionally, HL-1 cardiomyocytes were cultured under high glucose (HG) conditions and treated with dapagliflozin, with or without sirtinol. In the rat model, dapagliflozin improved atrial fibrosis and reduced AF inducibility and duration-effects that were partially reversed by sirtinol. These findings suggest that dapagliflozin may alleviate cardiac fibrosis and atrial arrhythmia by modulating SIRT1. In HL-1 cells under HG conditions, dapagliflozin reduced apoptosis, restored autophagy and mitophagy, and improved calcium channel activity. However, sirtinol negated these protective effects. Dapagliflozin helped normalize autophagy, mitophagy, and calcium handling, while sirtinol diminished its protective effects, highlighting the key role of SIRT1 in regulating calcium handling under HG conditions. Overall, SIRT1 plays a protective role in diabetic cardiomyopathy by reducing apoptosis, regulating autophagy and mitophagy, and modulating calcium channel activity. Dapagliflozin reduces AF duration and inducibility in the STZ model, likely through SIRT1 upregulation and calcium channel modulation.

Role of Nicotinamide in the Pathogenesis of Actinic Keratosis: Implications for NAD+/SIRT1 Pathway

Actinic keratosis (AK) is a precursor to invasive squamous cell carcinoma, making early diagnosis and treatment essential to prevent progression. Among available therapeutic options, nicotinamide (NAM) has shown potential in reducing AK progression. NAM is a precursor of nicotinamide adenine dinucleotide (NAD+), which activates sirtuin (SIRT)1, a protein with anti-cancer properties. Although the role of SIRT1 in AK is still debated, no data currently exist on the systemic modulation of this protein in AK. Therefore, this study aims to evaluate whether NAM, by increasing serum NAD+ levels, may promote SIRT1 activation in peripheral blood mononuclear cells (PBMCs) in AK patients. Thirty patients were enrolled and treated with NAM for 24 months. Hematological, biochemical, and skin condition assessments were conducted, alongside the measurement of SIRT1 and NAD+ levels. A decrease in basophils, monocytes, total cholesterol, and blood glucose levels was observed in the study group, along with a reduction in AK lesions. Notably, NAM treatment significantly enhanced serum NAD+ levels, and nuclear SIRT1 activity in PBMCs. In conclusion, NAM administration significantly reduced AK progression in a NAD+/SIRT1-dependent manner, supporting its role as a chemopreventive agent in AK management.

Retraction: Effects of microRNA-211 on proliferation and apoptosis of lens epithelial cells by targeting SIRT1 gene in diabetic cataract mice.

Retraction: Effects of microRNA-211 on proliferation and apoptosis of lens epithelial cells by targeting SIRT1 gene in diabetic cataract mice.

Liver-gut axis signaling regulates circadian energy metabolism in shift workers.

Circadian rhythm is critical to maintaining the whole-body metabolic homeostasis of an organism. Chronic disruption of circadian rhythm by shift work is an important risk factor for metabolic diseases. Fibroblast growth factor 15/19 (FGF15/19), a key component in the liver-gut axis, potently suppresses bile acid (BA) synthesis and improves insulin sensitivity. FGF15/19 emerges as a novel pharmaceutical target for prevention and treatment of metabolic diseases. The nicotinamide adenine dinucleotide (NAD+)-dependent sirtuin 1 (SIRT1) deacetylase plays an important role in the maintenance of hepatic homeostasis by linking hepatic metabolism to circadian rhythm. Here, our clinical study identified that circadian rhythmicity and levels of plasma FGF19 and BA profiling, and cellular NAD+-dependent SIRT1 signaling were disturbed in night shift (NS, n = 10) compared to day shift (DS, n = 12) nurses. Our invitro data showed that recombinant FGF19 protein rescued cellular circadian rhythm disrupted by SIRT1 inhibitors. Furthermore, we determined the effect of FGF15 on circadian rhythm and hepatic metabolism in wild-type (WT), Fgf15 knockout (KO), and Fgf15 transgenic (TG) mice. The expressions of circadian-controlled genes (CCGs) involved in SIRT1 signaling, BA and lipid metabolism, and inflammation were disrupted in Fgf15 KO compared to WT and/or Fgf15 TG mice. Moreover, systemic FGF15 deficiency led to the circadian disturbance of NAD+-dependent SIRT1 signaling and significant reduction during nighttime in mice. These findings suggest that FGF15/19 regulates the circadian energy metabolism, which warrants further studies as a putative prognostic biomarker and pharmaceutical target for preventing against metabolic diseases associated with chronic shift work.

Disruption of PCSK9 Suppresses Inflammation and Attenuates Abdominal Aortic Aneurysm Formation.

Abdominal aortic aneurysm (AAA) is a chronic vascular inflammatory disease without effective medications. PCSK9 (proprotein convertase subtilisin/kexin 9), a serine protease from the proprotein convertase family, has recently been associated with AAA in human genome-wide association studies. However, its role in AAA is unknown. Transcriptional and histological expression of PCSK9 was examined in AAA tissues and healthy controls. The impact of PCSK9 deletion and inhibition on AAA formation was assessed in mice with hyperlipidemia and Ang II (angiotensin II) overproduction. AAA lesion morphology was assessed by tissue staining. MMP (matrix metalloproteinase) activity was evaluated by gelatin zymography, and leukocyte-vessel wall interaction was monitored by intravital microscopy. RNA sequencing was used to characterize the downstream signaling of PCSK9. PCSK9 expression was upregulated and colocalized with macrophages in human and mouse AAAs. Pcsk9 deletion attenuated AAA formation, improved survival, and decreased systemic inflammation, without altering circulating cholesterol levels. Pcsk9 deficiency reduced aortic infiltration of macrophages and elastin degradation, without affecting vascular smooth muscle cell apoptosis and proliferation. Mechanistically, PCSK9 was essential in leukocyte-endothelium adhesion and expression of proinflammatory cytokines and MMP9 by macrophages. RNA sequencing of stimulated macrophages revealed that Pcsk9 deficiency upregulated histone deacetylase SIRT1 (sirtuin-1) and suppressed NF-κB (nuclear factor-κB) inflammatory signaling. SIRT1 inhibition attenuated the proinflammatory actions of PCSK9. Furthermore, administration of PCSK9 small interfering RNA or antibody constrained AAA formation/progression and inhibited vascular inflammation. PCSK9 critically mediates macrophage inflammation and elastin degradation, promoting AAA formation. PCSK9 inhibitors bear a promise to curtail AAA, beyond being used as cholesterol-lowering drugs.