Mitochondrial antioxidant elamipretide improves learning and memory impairment induced by chronic sleep deprivation in mice

BACKGROUND

The inflammation and synaptic dysfunction induced by mitochondrial dysfunction play essential roles in the learning and memory impairment associated with sleep dysfunction. Elamipretide (SS-31), a novel mitochondrion-targeted antioxidant, was proven to improve mitochondrial dysfunction, the inflammatory response, synaptic dysfunction, and cognitive impairment in models of cerebral ischemia, sepsis, and type 2 diabetes. However, the potential for SS-31 to improve the cognitive impairment induced by chronic sleep deprivation (CSD) and its underlying mechanisms is unknown.

METHODS

Adult c57BL/6J mice were subjected to CSD for 21 days using an activity wheel accompanied by daily intraperitoneal injection of SS-31 (5 mg/kg). The novel object recognition and Morris water maze test were used to evaluate hippocampus-dependent cognitive function. Western blotting and reverse transcription-quantitative polymerase chain reaction assays were used to determine the effects of CSD and SS-31 on markers of mitochondria, inflammation response, and synaptic function. Enzyme-linked immunosorbent assays were used to examine the levels of proinflammatory cytokines.

RESULTS

SS-31 could improve the cognitive impairment induced by CSD. In particular, SS-31 treatment restored the CSD-induced decrease in sirtuin 1 (SIRT1) and peroxisome proliferator-activated receptor γ coactivator alpha levels and the increase in levels nuclear factor kappa-B and inflammatory cytokines, including interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha. Furthermore, SS-31 significantly increased the levels of brain-derived neurotrophic factor, postsynaptic density protein-95, and synaptophysin in CSD mice.

CONCLUSION

Taken together, these results suggest that SS-31 could improve CSD-induced mitochondrial biogenesis dysfunction, inflammatory response, synaptic dysfunction, and cognitive impairment by increasing SIRT1 expression levels.

Cordycepin, a bioactive compound from Cordyceps spp., moderates Alzheimer's disease-associated pathology via anti-oxidative stress and autophagy activation

Alzheimer's causes cognitive dysfunction. This study investigated the neuro-promoting effects of cordycepin on amyloid-beta precursor protein (APP) synthesis in human neuroblastoma SH-SY5Y cells. Cordycepin was found to boost SH-SY5Y cell proliferation and decreased AD pathology. APP, PS1, and PS2 were downregulated whereas ADAM10 and SIRT1 were upregulated by cordycepin. Cordycepin also reduced APP secretion in a dose-dependent manner. Cordycepin alleviated oxidative stress by the upregulation of GPX and SOD, as well as autophagy genes (LC3, ATG5, and ATG12). Cordycepin activity was also found to be SIRT1-dependent. Therefore, cordycepin may relieve the neuronal degeneration caused by APP overproduction, and oxidative stress.

Myricanol improves metabolic profiles in dexamethasone induced lipid and protein metabolism disorders in mice

Myricanol (MY) is one of the main active components from bark of Myrica Rubra. It is demonstrated that MY rescues dexamethasone (DEX)-induced muscle dysfunction via activating silent information regulator 1 (SIRT1) and increasing adenosine 5'-monophosphate-activated protein kinase (AMPK) phosphorylation. Since SIRT1 and AMPK are widely involved in the metabolism of nutrients, we speculated that MY may exert beneficial effects on DEX-induced metabolic disorders. This study for the first time applied widely targeted metabolomics to investigate the beneficial effects of MY on glucose, lipids, and protein metabolism in DEX-induced metabolic abnormality in mice. The results showed that MY significantly reversed DEX-induced soleus and gastrocnemius muscle weight loss, muscle fiber damage, and muscle strength loss. MY alleviated DEX-induced metabolic disorders by increasing SIRT1 and glucose transporter type 4 (GLUT4) expressions. Additionally, myricanol prevented muscle cell apoptosis and atrophy by inhibiting caspase 3 cleavages and muscle ring-finger protein-1 (MuRF1) expression. Metabolomics showed that MY treatment reversed the serum content of carnitine ph-C1, palmitoleic acid, PS (16:0_17:0), PC (14:0_20:5), PE (P-18:1_16:1), Cer (t18:2/38:1(2OH)), four amino acids and their metabolites, and 16 glycerolipids in DEX mice. Kyoto encyclopedia of genes and genomes (KEGG) and metabolic set enrichment analysis (MSEA) analysis revealed that MY mainly affected metabolic pathways, glycerolipid metabolism, lipolysis, fat digestion and absorption, lipid and atherosclerosis, and cholesterol metabolism pathways through regulation of metabolites involved in glutathione, butanoate, vitamin B6, glycine, serine and threonine, arachidonic acid, and riboflavin metabolism. Collectively, MY can be used as an attractive therapeutic agent for DEX-induced metabolic abnormalities.

Platelet-rich plasma-derived extracellular vesicles inhibit NF-κB/NLRP3 pathway-mediated pyroptosis in intervertebral disc degeneration via the MALAT1/microRNA-217/SIRT1 axis

BACKGROUND

Intervertebral disc degeneration (IDD) is a main contributor to lower back pain, and compression stress-induced apoptosis of nucleus pulposus (NP) cells and extracellular matrix (ECM) degradation has been implicated in the IDD progression. The functions of platelet-rich plasma (PRP)-derived extracellular vesicles (PRP-EVs) in regulating these biological processes remain unclear in IDD. Here, we aimed to investigate the key role of long noncoding RNA (lncRNA) MALAT1 incorporated in PRP-EVs in IDD.

METHODS

Tert-butyl hydroperoxide (TBHP)-induced damage in NP cells was treated with PRP-EVs extracted from healthy volunteers, followed by MTT, EdU, TUNEL, and Western blot assays. IDD mice were also treated with PRP-EVs. Histomorphological and pathological changes were evaluated. The pyroptosis of cells and the degradation of ECM were detected by ELISA and immunohistochemistry. We screened the differentially expressed lncRNAs in NP cells after PRP-EVs treatment by microarray analysis. The downstream targets of MALAT1 in NP cells were predicted and validated by rescue experiments.

FINDINGS

TBHP induction reduced cell proliferation and exacerbated pyroptosis and ECM degradation, and PRP-EVs inhibited TBHP-induced cell damage. PRP-EVs-treated mice with IDD had reduced Thompson scores, increased NP tissue content, and restored ECM. PRP-EVs upregulated MALAT1 expression in vivo and in vitro, whereas MALAT1 downregulation exacerbated NP cell pyroptosis and ECM degradation. MALAT1 upregulated SIRT1 expression by downregulating microRNA (miR)-217 in NP cells. SIRT1 blocked the NF-κB/NLRP3 pathway-mediated pyroptosis, thereby alleviating IDD.

INTERPRETATION

PRP-EVs deliver MALAT1 to regulate miR-217/SIRT1, thereby controlling NP cell pyroptosis in IDD.

PGC-1α activation boosts exercise-dependent cellular response in the skeletal muscle

The role of Peroxisome proliferator-activated receptor-gamma coactivator alpha (PGC-1α) in fat metabolism is not well known. In this study, we compared the mechanisms of muscle-specific PGC-1α overexpression and exercise-related adaptation-dependent fat metabolism. PGC-1α trained (PGC-1α Ex) and wild-trained (wt-ex) mice were trained for 10 weeks, five times a week at 30 min per day with 60 percent of their maximal running capacity. The PGC-1α overexpressed animals exhibited higher levels of Fibronectin type III domain-containing protein 5 (FNDC5), 5' adenosine monophosphate-activated protein kinase alpha (AMPK-α), the mammalian target of rapamycin (mTOR), Sirtuin 1 (SIRT1), Lon protease homolog 1 (LONP1), citrate synthase (CS), succinate dehydrogenase complex flavoprotein subunit A (SDHA), Mitofusin-1 (Mfn1), endothelial nitric oxide synthase (eNOS), Hormone-sensitive lipase (HSL), adipose triglyceride lipase (ATGL), G protein-coupled receptor 41 (GPR41), and Phosphatidylcholine Cytidylyltransferase 2 (PCYT2), and lower levels of Sirtuin 3 (SIRT3) compared to wild-type animals. Exercise training increased the protein content levels of SIRT1, HSL, and ATGL in both the wt-ex and PGC-1α trained groups. PGC-1α has a complex role in cellular signaling, including the upregulation of lipid metabolism-associated proteins. Our data reveals that although exercise training mimics the effects of PGC-1α overexpression, it incorporates some PGC-1α-independent adaptive mechanisms in fat uptake and cell signaling.

SIRT1 mediates breast cancer development and tumorigenesis controlled by estrogen-related receptor β

Silent mating type information regulation 2 homolog 1 (SIRT1) is a class III histone deacetylase (HDAC) that is NAD + dependent and essential for metabolism, senescence, and cell survival. SIRT1 is overexpressed in several cancers, including breast cancer. SIRT1 is a well-known target gene of the estrogen receptor alpha (ER alpha) and is closely related to ER alpha deacetylation. Transcription factor Estrogen-related receptors (ERRs) share sequence homology with ERs in the DNA-binding domain, therefore, the possibility of sharing target genes between them is high. Our current research aims to gain insight into the function of ERRβ in regulating the activity of SIRT1 during the progression of breast cancer. ER-positive (ER + ve) breast cancer cells and tissues had considerably enhanced SIRT1 expression. Six potential ERRE sites were identified by analysis of the 5' upstream region of SIRT1, and both in vitro and in vivo experiments supported their presence. We found SIRT1 to be up-regulated in ERRβ overexpressed ER + ve breast cancer cells. Furthermore, our findings suggested that ectopic production of ERR and PCAF would increase SIRT1 activity. Our findings also indicated that ectopic production of ERRβ and PCAF increased SIRT1 activity. With sufficient evidence demonstrating the substantial involvement of SIRT1 in cell proliferation, migration, and colony formation capability, we were also able to illustrate the tumorigenic role of SIRT1. Overall, our findings highlight SIRT1's tumorigenic influence on breast cancer and suggest that SIRT1 inhibitors might serve as potential therapeutic drugs for the treatment of breast cancer.

SIRT1: Harnessing multiple pathways to hinder NAFLD

Non-alcoholic fatty liver disease (NAFLD) encompasses hepatic steatosis, non-alcoholic steatohepatitis (NASH), fibrosis, cirrhosis, and hepatocellular carcinoma. It is the primary cause of chronic liver disorders, with a high prevalence but no approved treatment. Therefore, it is indispensable to find a trustworthy therapy for NAFLD. Recently, mounting evidence illustrates that Sirtuin 1 (SIRT1) is strongly associated with NAFLD. SIRT1 activation or overexpression attenuate NAFLD, while SIRT1 deficiency aggravates NAFLD. Besides, an array of therapeutic agents, including natural compounds, synthetic compounds, traditional Chinese medicine formula, and stem cell transplantation, alleviates NALFD via SIRT1 activation or upregulation. Mechanically, SIRT1 alleviates NAFLD by reestablishing autophagy, enhancing mitochondrial function, suppressing oxidative stress, and coordinating lipid metabolism, as well as reducing hepatocyte apoptosis and inflammation. In this review, we introduced the structure and function of SIRT1 briefly, and summarized the effect of SIRT1 on NAFLD and its mechanism, along with the application of SIRT1 agonists in treating NAFLD.

Rap1GAP exacerbates myocardial infarction by regulating the AMPK/SIRT1/NF-κB signaling pathway

Rap1 GTPase-activating protein (Rap1GAP) is an important tumor suppressor. The purpose of this study was to investigate the role of Rap1GAP in myocardial infarction (MI) and its potential mechanism. Left anterior descending coronary artery ligation was performed on cardiac-specific Rap1GAP conditional knockout (Rap1GAP-CKO) mice and control mice with MI. Seven days after MI, Rap1GAP expression in the hearts of control mice peaked, the expression of proapoptotic markers (Bax and cleaved caspase-3) increased, the expression of antiapoptotic factors (Bcl-2) decreased, and the expression of the inflammatory factors IL-6 and TNF-α increased; thus, apoptosis occurred, inflammation, infarct size, and left ventricular dysfunction increased, while the heart changes caused by MI were alleviated in Rap1GAP-CKO mice. Mouse heart tissue was obtained for transcriptome sequencing, and gene set enrichment analysis (GSEA) was used to analyze Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. We found that Rap1GAP was associated with the AMPK and NF-κB signaling pathways and that Rap1GAP inhibited AMPK/SIRT1 and activated the NF-κB signaling pathway in model animals. Similar results were observed in primary rat myocardial cells subjected to oxygen-glucose deprivation (OGD) to induce ischemia and hypoxia. Activating AMPK with the AMPK activator 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) reversed the damage caused by Rap1GAP overexpression in cardiomyocytes. In addition, the coimmunoprecipitation results showed that exogenous Rap1GAP interacted with AMPK. Rap1GAP was verified to regulate the AMPK SIRT1/NF-κB signaling pathway and exacerbate the damage to myocardial cells caused by ischemia and hypoxia. In conclusion, our results suggest that Rap1GAP promotes MI by modulating the AMPK/SIRT1/NF-κB signaling pathway and that Rap1GAP may be a therapeutic target for MI treatment in the future.

Targeting SIRT1, NLRP3 inflammasome, and Nrf2 signaling with chrysin alleviates the iron-triggered hepatotoxicity in rats

Blood transfusion-requiring diseases such as sickle cell anemia and thalassemia are characterized by an imbalance between iron intake and excretion, resulting in an iron overload (IOL) disorder. Hepatotoxicity is prevalent under the IOL disorder because of the associated hepatocellular redox and inflammatory perturbation. The current work was devoted to investigate the potential protection against the IOL-associated hepatotoxicity using chrysin, a naturally-occurring flavone. IOL model was created in male Wistar rats by intraperitoneal injection of 100 mg/kg elemental iron subdivided on five equal injections; one injection was applied every other day over ten days. Chrysin was administered in a daily dose of 50 mg/kg over the ten-day iron treatment period. On day eleven, blood and liver samples were collected and subjected to histopathological, biochemical, and molecular investigations. Chrysin suppressed the IOL-induced hepatocellular damage as revealed by decreased serum activity of the intracellular liver enzymes and improved liver histological picture. Oxidative damage biomarkers, and pro-inflammatory cytokines were significantly suppressed. Mechanistically, the levels of the redox and inflammation-controlling proteins SIRT1 and PPARγ were efficiently up-regulated. The liver iron load, NLRP3 inflammasome activation, and NF-κB acetylation and nuclear shift were significantly suppressed in the iron-intoxicated rats. Equally important, the level of the antioxidant protein Nrf2 and its target HO-1 were up-regulated. In addition, chrysin significantly ameliorated the IOL-induced apoptosis as indicated by reduction in caspase-3 activity and modulation of BAX and Bcl2 protein abundance. Together, these findings highlight the alleviating activity of chrysin against the IOL-associated hepatotoxicity and shed light on the role of SIRT1, NLRP3 inflammasome, and Nrf2 signaling as potential contributing molecular mechanisms.

SIRT1 activation ameliorates rhesus monkey liver fibrosis by inhibiting the TGF-β/smad signaling pathway

TGF-β/Smad signaling pathway plays an important role in the pathogenesis and progression of liver fibrosis. Silent information regulator 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD+) dependent enzyme and responsible for deacetylating the proteins. Increasing numbers of reports have shown that the molecular mechanism of SIRT1 as an effective therapeutic target for liver fibrosis but the transformation is not very clear. In the present study, liver fibrotic tissues were screened by staining with Masson, hematoxylin-eosin staining (H&E) and Immunohistochemistry (IHC) for histopathological observation from the liver biopsy of seventy-seven rhesus monkey, which fixed with 4% paraformaldehyde (PFA) after treatment with high-fat diet (HFD) for two years. And the liver function was further determined by serum biochemical tests. The mRNA levels and protein expression of rat hepatic stellate (HSC-T6) cells were determined after treatment with Resveratrol (RSV) and Nicotinamide (NAM), respectively. The results showed that with the increasing of hepatic fibrosis in rhesus monkeys, the liver function impaired, and the transforming growth factor-β1 (TGF-β1), p-Smad3 (p-Smad3) and alpha-smooth muscle actin (α-SMA) was up-regulated, while SIRT1 and Smad7 were down-regulated. Moreover, when stimulated the HSC-T6 with RSV to activate SIRT1 for 6, 12, and 24 h, the results showed that RSV promoted the expression of smad7, while the expression of TGF-β1, p-Smad3 and α-SMA were inhibited. In contrast, when the cells stimulated with NAM to inhibit SIRT1 for 6, 12, and 24 h, the Smad7 expression was decreased, while TGF-β1, p-Smad3, and α-SMA expressions were increased. These results indicate that SIRT1 acts as an important protective factor for liver fibrosis, which may be attributed to inhibiting the signaling pathway of TGF-β/Smad in hepatic fibrosis of the rhesus monkey.

Effect of polydimethylsiloxane surface morphology on osteogenic differentiation of mesenchymal stem cells through SIRT1 signalling pathway

Constructing surface topography with a certain roughness is a widely used, non-toxic, cost-effective and effective method for improving the microenvironment of cells, promoting the proliferation and osteogenic differentiation of mesenchymal stem cells (MSCs), and promoting the osseointegration of grafts and further improving their biocompatibility under clinical environmental conditions. SIRT1 plays an important regulatory role in the osteogenic differentiation of bone marrow-derived MSCs (BM-MSCs). However, it remains unknown whether SIRT1 plays an important regulatory role in the osteogenic differentiation of BM-MSCs with regard to surface morphology. Polydimethylsiloxane (PDMS) with different surface morphologies were prepared using different grits of sandpaper. The value for BMSCs added on different surfaces was detected by cell proliferation assays. RT-qPCR and Western blotting were performed to detect SIRT1 activation and osteogenic differentiation of MSCs. Osteogenesis of MSCs was detected by alkaline phosphatase (ALP) and alizarin red S staining. SIRT1 inhibition experiments were performed to investigate the role of SIRT1 in the osteogenic differentiation of MSCs induced by surface morphology. We found that BM-MSCs have better value and osteogenic differentiation ability on a surface with roughness of PDMS-1000M. SIRT1 showed higher gene and protein expression on a PDMS-1000M surface with a roughness of 13.741 ± 1.388 µm. The promotion of the osteogenic differentiation of MSCs on the PDMS-1000M surface was significantly decreased after inhibiting SIRT1 expression. Our study demonstrated that a surface morphology with certain roughness can activate the SIRT1 pathway of MSCs and promote the osteogenic differentiation of BMSCs via the SIRT1 pathway.

d-galactose causes embryonic development arrest and placental development disorders in mice by increasing ROS and inhibiting SIRT1/FOXO3a axis

INTRODUCTION

Does an elevation in d-Galactose (D-Gal) levels within the body contribute to abnormal embryonic development and placental dysfunction during pregnancy?

METHODS

Mouse embryos were cultivated to the blastocyst stage under varying concentrations of D-Gal. The blastocyst formation rate was measured, and the levels of reactive oxygen species (ROS), sirtuin 1 (SIRT1), and forkhead box O3a (FOXO3a) in blastocysts were assessed. Mice were intraperitoneally injected with either saline or D-Gal with or without SRT1720. On the 14th day of pregnancy, the fetal absorption rate and placental weight were recorded. Placental levels of superoxide dismutase (SOD) and malondialdehyde (MDA) were determined. The expression of senescence-related factors, such as senescence-associated β-galactosidase (SA-β-gal) in the placenta was examined, and the expression of placental SIRT1, FOXO3a and p21 was evaluated by immunohistochemistry and Western blotting.

RESULTS

D-Gal adversely affects early embryonic development in vitro, resulting in a decreased blastocyst formation rate. Furthermore, D-Gal downregulates SIRT1 and FOXO3a while increasing ROS levels in blastocysts. Concurrently, D-Gal induces placental dysfunction, characterized by an elevated fetal absorption rate, reduced placental weight, diminished SOD activity, and increased MDA content. The senescence-related factor SA-β-gal was detected in the placenta, along with altered expression of placental SIRT1, FOXO3a, and p21. The SIRT1 agonist SRT1720 mitigated this damage by increasing SIRT1 and FOXO3a expression.

DISCUSSION

The inhibition of early embryonic development and placental dysfunction induced by D-Gal may be attributed to the dysregulation of SIRT1. Activating SIRT1 emerges as a potentially effective strategy for alleviating the adverse effects of D-Gal exposure.

SIRT1: An Intermediator of Key Pathways Regulating Pulmonary Diseases

Silent information regulator type-1 (SIRT1), a nicotinamide adenine dinucleotide+-dependent deacetylase, is a member of the sirtuins family and has unique protein deacetylase activity. SIRT1 participates in physiological as well as pathophysiological processes by targeting a wide range of protein substrates and signalings. In this review, we described the latest progress of SIRT1 in pulmonary diseases. We have introduced the basic information and summarized the prominent role of SIRT1 in several lung diseases, such as acute lung injury, acute respiratory distress syndrome, chronic obstructive pulmonary disease, lung cancer, and aging-related diseases.

Liraglutide prevents cellular senescence in human retinal endothelial cells (HRECs) mediated by SIRT1: an implication in diabetes retinopathy

Diabetes mellitus (DM) is a chronic metabolic disorder affecting millions of people worldwide, characterized by dysregulated glucose homeostasis and hyperglycemia. Diabetic retinopathy (DR) is one of the serious multisystemic complications. Aging is an important risk factor for DR. Endothelial sirtuin 1 (SIRT1) plays an important role in regulating the pathophysiology of glucose metabolism, cellular senescence, and aging. Liraglutide, an analog of Glucagon-like peptide 1 (GLP-1), has been widely used in the treatment of DM. However, the effects of Liraglutide on DR are less reported. Here, we investigated whether treatment with Liraglutide has beneficial effects on high glucose (HG)-induced injury in human retinal microvascular endothelial cells (HRECs). First, we found that exposure to HG reduced the expression of glucagon-like peptide 1 receptor 1 (GLP-1R). Additionally, Liraglutide ameliorated HG-induced increase in the expression of vascular endothelial growth factor-A (VEGF-A) and interleukin 6 (IL-6). Importantly, Liraglutide ameliorated cellular senescence and increased telomerase activity in HG-challenged HRECs. Liraglutide also reduced the levels of p53 and p21. Mechanistically, Liraglutide restored the expression of SIRT1 against HG. In contrast, the knockdown of SIRT1 abolished the protective effects of Liraglutide in cellular senescence of HRECs. Our findings suggest that Liraglutide might possess a benefit on DR mediated by SIRT1.

Aspirin-Mediated Acetylation of SIRT1 Maintains Intestinal Immune Homeostasis

Aspirin, also named acetylsalicylate, can directly acetylate the side-chain of lysine in protein, which leads to the possibility of unexplained drug effects. Here, the study used isotopic-labeling aspirin-d3 with mass spectrometry analysis to discover that aspirin directly acetylates 10 HDACs proteins, including SIRT1, the most studied NAD+-dependent deacetylase. SIRT1 is also acetylated by aspirin in vitro. It is also identified that aspirin directly acetylates lysine 408 of SIRT1, which abolishes SIRT1 deacetylation activity by impairing the substrates binding affinity. Interestingly, the lysine 408 of SIRT1 can be acetylated by CBP acetyltransferase in cells without aspirin supplement. Aspirin can inhibit SIRT1 to increase the levels of acetylated p53 and promote p53-dependent apoptosis. Moreover, the knock-in mice of the acetylation-mimic mutant of SIRT1 show the decreased production of pro-inflammatory cytokines and maintain intestinal immune homeostasis. The study indicates the importance of the acetylated internal functional site of SIRT1 in maintaining intestinal immune homeostasis.

Heterogeneous nuclear ribonucleoprotein F deficiency in mouse podocyte promotes podocytopathy mediated by methyltransferase-like 14 nuclear translocation resulting in Sirtuin 1 gene inhibition

Heterogeneous nuclear ribonucleoprotein F (HnRNP F) is a key regulator for nucleic acid metabolism; however, whether HnRNP F expression is important in maintaining podocyte integrity is unclear. Nephroseq analysis from a registry of human kidney biopsies was performed. Age- and sex-matched podocyte-specific HnRNP F knockout (HnRNP FPOD KO) mice and control (HnRNP Ffl/fl) were studied. Podocytopathy was induced in male mice (more susceptible) either by adriamycin (ADR)- or low-dose streptozotocin treatment for 2 or 8 weeks. The mouse podocyte cell line (mPODs) was used in vitro. Nephroseq data in three human cohorts were varied greatly. Both sexes of HnRNP FPOD KO mice were fertile and appeared grossly normal. However, male 20-week-old HnRNP FPOD KO than HnRNP Ffl/fl mice had increased urinary albumin/creatinine ratio, and lower expression of podocyte markers. ADR- or diabetic- HnRNP FPOD KO (vs. HnRNP Ffl/fl) mice had more severe podocytopathy. Moreover, methyltransferase-like 14 (Mettl14) gene expression was increased in podocytes from HnRNP FPOD KO mice, further enhanced in ADR- or diabetic-treated HnRNP FPOD KO mice. Consequently, this elevated Mettl14 expression led to sirtuin1 (Sirt1) inhibition, associated with podocyte loss. In mPODs, knock-down of HnRNP F promoted Mettl14 nuclear translocation, which was associated with podocyte dysmorphology and Sirt1 inhibition-mediated podocyte loss. This process was more severe in ADR- or high glucose- treated mPODs. Conclusion: HnRNP F deficiency in podocytes promotes podocytopathy through activation of Mettl14 expression and its nuclear translocation to inhibit Sirt1 expression, underscoring the protective role of HnRNP F against podocyte injury.

SIRT1-Rab7 axis attenuates NLRP3 and STING activation through late endosomal-dependent mitophagy during sepsis-induced acute lung injury

BACKGROUND

Acute lung injury (ALI) is a leading cause of mortality in patients with sepsis due to proinflammatory endothelial changes and endothelial permeability defects. Mitochondrial dysfunction is recognized as a critical mediator in the pathogenesis of sepsis-induced ALI. Although mitophagy regulation of mitochondrial quality is well recognized, little is known about its role in lung ECs during sepsis-induced ALI. Sirtuin 1 (SIRT1) is a histone protein deacetylase involved in inflammation, mitophagy, and cellular senescence. Here, the authors show a type of late endosome-dependent mitophagy that inhibits NLRP3 and STING activation through SIRT1 signaling during sepsis-induced ALI.

METHODS

C57BL/6J male mice with or without administration of the SIRT1 inhibitor EX527 in the CLP model and lung ECs in vitro were developed to identify mitophagy mechanisms that underlie the cross-talk between SIRT1 signaling and sepsis-induced ALI.

RESULTS

SIRT1 deficient mice exhibited exacerbated sepsis-induced ALI. Knockdown of SIRT1 interfered with mitophagy through late endosome Rab7, leading to the accumulation of damaged mitochondria and inducing excessive mitochondrial reactive oxygen species (mtROS) generation and cytosolic release of mitochondrial DNA (mtDNA), which triggered NLRP3 inflammasome and the cytosolic nucleotide sensing pathways (STING) over-activation. Pharmacological inhibition of STING and NLRP3 i n vivo or genetic knockdown in vitro reversed SIRT1 deficiency mediated endothelial permeability defects and endothelial inflammation in sepsis-induced ALI. Moreover, activation of SIRT1 with SRT1720 in vivo or overexpression of SIRT1 in vitro protected against sepsis-induced ALI.

CONCLUSION

These findings suggest that SIRT1 signaling is essential for restricting STING and NLRP3 hyperactivation by promoting endosomal-mediated mitophagy in lung ECs, providing potential therapeutic targets for treating sepsis-induced ALI.

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

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

Intranasal Delivery of Mitochondria Attenuates Brain Injury by AMPK and SIRT1/PGC-1α Pathways in a Murine Model of Photothrombotic Stroke

Ischemic stroke is one of the major causes of morbidity and mortality worldwide. Mitochondria play a vital role in the pathological processes of cerebral ischemic injury, but its transplantation and underlying mechanisms remain unclear. In the present study, we examined the effects of mitochondrial therapy on the modulation of AMPK and SIRT1/PGC-1α signaling pathway, oxidative stress, and NLRP3 inflammasome activation after photothrombotic ischemic stroke (pt-MCAO). The adult male mice were subjected to the pt-MCAO in which the proximal-middle cerebral artery was exposed with a 532-nm laser beam for 4 min by retro-orbital injection of a photosensitive dye (Rose Bengal: 15 mg/kg) before the laser light exposure and isolated mitochondria (100 μg protein) were administered intranasally at 30 min, 24 h, and 48 h following post-stroke. After 72 h, mice were tested for neurobehavioral outcomes and euthanized for infarct volume, brain edema, and molecular analysis. First, we found that mitochondria therapy significantly decreased brain infarct volume and brain edema, improved neurological dysfunction, attenuated ischemic stroke-induced oxidative stress, and neuroinflammation. Second, mitochondria treatment inhibited NLRP3 inflammasome activation. Finally, mitochondria therapy accelerated p-AMPKα(Thr172) and PGC-1α expression and resorted SIRT1 protein expression levels in pt-MCAO mice. In conclusion, our results demonstrate that mitochondria therapy exerts neuroprotective effects by inhibiting oxidative damage and inflammation, mainly dependent on the heightening activation of the AMPK and SIRT1/PGC-1α signaling pathway. Thus, intranasal delivery of mitochondria might be considered a new therapeutic strategy for ischemic stroke treatment.

Fucoxanthin ameliorates endoplasmic reticulum stress and inhibits apoptosis and alleviates intervertebral disc degeneration in rats by upregulating Sirt1

Endoplasmic reticulum stress (ERS) and apoptosis of nucleus pulposus (NP) cells are considered to be the main pathological factors of intervertebral disc degeneration (IDD). Fucoxanthin (FX), a marine carotenoid extracted from microalgae, has antioxidant, anti-inflammatory, and anticancer properties. The aim of this study was to investigate the effect of FX on NP cells induced by oxidative stress and its molecular mechanism. Primary NP cells of the lumbar vertebrae of rats were extracted and tested in vitro. qRT-PCR, western blot, immunofluorescence, and TUNEL staining were used to detect apoptosis, ERS, extracellular matrix (ECM), and Sirt1-related pathways. In vivo experiments, the recovery of IDD rats was determined by X-ray, hematoxylin and eosin, Safranin-O/Fast Green, Alcian staining, and immunohistochemistry. Our study showed that oxidative stress induced ERS, apoptosis, and ECM degradation in NP cells. After the use of FX, the expression of Sirt1 was up-regulated, the activation of PERK-eIF2α-ATF4-CHOP was decreased, and apoptosis and ECM degradation were decreased. At the same time, FX improved the degree of disc degeneration in rats in vivo. Our study demonstrates the effect of FX on improving IDD in vivo and in vitro, suggesting that FX may be a potential drug for the treatment of IDD.

Perfluorotetradecanoic acid exposure to adult male rats stimulates corticosterone biosynthesis but inhibits aldosterone production

Perfluorotetradecanoic acid (PFTeDA) is a novel perfluoroalkyl substance that ubiquitously exists in the environment. However, whether PFTeDA affects adrenal cortex function remains unclear. Male Sprague-Dawley rats (age of 60 days) were daily administered with PFTeDA (0, 1, 5, and 10 mg/kg body weight) through gavage for 28 days. PFTeDA did not change body and adrenal gland weights. PFTeDA markedly elevated serum corticosterone level at 10 mg/kg but lowering serum aldosterone level at this dosage without influencing serum adrenocorticotropic hormone level. PFTeDA thickened zona fasciculata without affecting zona glomerulosa. PFTeDA remarkably upregulated the expression of corticosterone biosynthetic genes (Mc2r, Scarb1, Star, Cyp21, Cyp11b1, and Hsd11b1) and their proteins, whereas downregulating aldosterone biosynthetic enzyme Cyp11b2 and its protein, thereby distinctly altering their serum levels. PFTeDA markedly downregulated the expression of antioxidant genes (Sod1 and Sod2) and their proteins at 10 mg/kg. PFTeDA significantly decreased SIRT1/PGC1α and AMPK signaling while stimulating AKT1/mTOR signaling. Corticosterone significantly inhibited testosterone production by adult Leydig cells at >0.1 μM in vitro; however aldosterone significantly stimulated testosterone production at 0.1 nM. In conclusion, exposure to PFTeDA at male rat adulthood causes corticosterone excess and aldosterone deficiency via SIRT1/PGC1α, AMPK, and AKT1/mTOR signals, which in turn additively leads to testosterone deficiency.

Engineering of VCAM-1-targeted nanostructured lipid carriers for delivery of melatonin against acute lung injury through SIRT1/NLRP3 mediated pyroptosis signaling pathway

Acute lung injury (ALI) is a prevalent and critical condition in clinical practice. Although certain pharmacological interventions have demonstrated benefits in preclinical studies, none have been proven entirely effective thus far. Therefore, the development of more efficient treatment strategies for ALI is imperative. In this study, we prepared nanostructured lipid carriers (NLCs) conjugated with anti-VCAM-1 antibodies to encapsulate melatonin (MLT), resulting in VCAM/MLT NLCs. This approach aimed to enhance the distribution of melatonin in lung vascular endothelial cells. The VCAM/MLT NLCs had an average diameter of 364 nm, high drug loading content, and a sustained drug release profile. Notably, the NLCs conjugated with anti-VCAM-1 antibodies demonstrated more specific cellular delivery mediated by the VCAM-1 receptors, increased cellular internalization, and enhanced accumulation in lung tissues. Treatment with VCAM/MLT NLCs effectively alleviated pulmonary inflammation by activating NLRP3 inflammasome-dependent pyroptosis through up-regulation of Sirtuin 1. Our findings suggest that VCAM/MLT NLCs demonstrate remarkable therapeutic effects on ALI in both in vitro and in vivo settings, making them a promising and efficient treatment strategy for ALI.

Pterostilbene alleviates cafeteria diet-induced obesity and underlying depression in adolescent male Swiss albino mice and affects insulin resistance, inflammation, HPA axis dysfunction and SIRT1 mediated leptin-ghrelin signaling

Cafeteria diet (CD) model for in-vivo studies mimics the western diet having imbalanced nutritional value, high caloric-density and palatability. Uncontrolled eating leads to the development of childhood obesity, poor self-esteem and depression due to its effects on brain development. Herbal supplements are novel inclusion in the management of obesity and mental well-being. Pterostilbene (PTE) found in blueberries and Pterocarpus marsupium heartwood, is known to prevent obesity in invivo models. Adolescent Swiss albino male mice were fed on CD for 70 days and the development of obesity was assessed by gain in body weight, abdominal circumference. Forced swim and tail suspension test confirmed depression in CD fed mice. Obesity induced depressed (OID) mice were treated with PTE (10, 20, 40 mg/kg), standard antiobesity drug cetilistat (10 mg/kg), antidepressant fluoxetine (10 mg/kg) for 28 days. Post treatment, PTE-treated mice showed reduction in BW and depression-like behavior analysed using paradigms such as sucrose preference, open field, marble burying, and resident intruder test in comparison to the CD group. Insulin resistance, lipid profile, antioxidant enzyme, inflammatory cytokines (NF-κB, IL-6, TNF α) and cortisol levels were mitigated by PTE. It also restored normal cellular architecture of the brain and adipose tissue and increased the Silent mating type information regulation 2 homolog1 (SIRT1), leptin and ghrelin receptors gene expression in the brain. Thus, it can be concluded that PTE might have inhibited OID like behavior in mice via inhibition of IR, modulating neuroinflammation and hypothalamic-pituitary-adrenal axis dysfunction and upregulating SIRT1 mediated leptin-ghrelin signaling.

TMF inhibits extracellular matrix degradation by regulating the C/EBPβ/ADAMTS5 signaling pathway in osteoarthritis

Osteoarthritis (OA) is a chronic joint disease, characterized by degenerative destruction of articular cartilage. Chondrocytes, the unique cell type in cartilage, mediate the metabolism of extracellular matrix (ECM), which is mainly constituted by aggrecan and type II collagen. A disintegrin and metalloproteinase with thrombospondin 5 (ADAMTS5) is an aggrecanase responsible for the degradation of aggrecan in OA cartilage. CCAAT/enhancer binding protein β (C/EBPβ), a transcription factor in the C/EBP family, has been reported to mediate the expression of ADAMTS5. Our previous study showed that 5,7,3',4'-tetramethoxyflavone (TMF) could activate the Sirt1/FOXO3a signaling in OA chondrocytes. However, whether TMF protected against ECM degradation by down-regulating C/EBPβ expression was unknown. In this study, we found that aggrecan expression was down-regulated, and ADAMTS5 expression was up-regulated. Knockdown of C/EBPβ could up-regulate aggrecan expression and down-regulate ADAMTS5 expression in IL-1β-treated C28/I2 cells. TMF could compromise the effects of C/EBPβ on OA chondrocytes by activating the Sirt1/FOXO3a signaling. Conclusively, TMF exhibited protective activity against ECM degradation by mediating the Sirt1/FOXO3a/C/EBPβ pathway in OA chondrocytes.

Linc01588 deletion inhibits the malignant biological characteristics of hydroquinone-induced leukemic cells via miR-9-5p/SIRT1

Leukemia caused by environmental chemical pollutants has attracted great attention, the malignant leukemic transformation model of TK6 cells induced by hydroquinone (HQ) has been previously found in our team. However, the type of leukemia corresponding to this malignant transformed cell line model needs further study and interpretation. Furthermore, the molecular mechanism of malignant proliferation of leukemic cells induced by HQ remains unclear. This study is the first to reveal the expression of aberrant genes in leukemic cells of HQ-induced malignant transformation, which may correspond to chronic lymphocytic leukemia (CLL). The expression of Linc01588, a long non-coding RNA (lncRNA), was significantly up-regulated in CLL patients and leukemic cell line model which previously described. After gain-of-function assays and loss-of-function assays, feeble cell viability, severe apoptotic phenotype and the increased secretion of TNF-α were easily observed in malignant leukemic TK6 cells with Linc01588 deletion after HQ intervention. The tumors derived from malignant TK6 cells with Linc01588 deletion inoculated subcutaneously in nude mice were smaller than controls. In CLL and its cell line model, the expression of Linc01588 and miR-9-5p, miR-9-5p and SIRT1 were negative correlation respectively in CLL and cell line model, while the expression of Linc01588 and SIRT1 were positive correlation. The dual-luciferase reporter assay showed that Linc01588 & miR-9-5p, miR-9-5p & SIRT1 could bind directly, respectively. Furthermore, knockdown of miR-9-5p successfully rescued the severe apoptotic phenotype and the increased secretion of TNF-α caused by the Linc01588 deletion, the deletion of Linc01588 in human CLL cell line MEC-2 could also inhibit malignant biological characteristics, and the phenotype caused by the deletion of Linc01588 could also be rescued after overexpression of SIRT1. Moreover, the regulation of SIRT1 expression in HQ19 cells by Linc01588 and miR-9-5 P may be related to the Akt/NF-κB pathway. In brief, Linc01588 deletion inhibits the malignant biological characteristics of HQ-induced leukemic cells via miR-9-5p/SIRT1, and it is a novel and hopeful clue for the clinical targeted therapy of CLL.