SIRT1 positively regulates autophagy and mitochondria function in embryonic stem cells under oxidative stress

Combined intake of blueberry juice and probiotics ameliorate mitochondrial dysfunction by activating SIRT1 in alcoholic fatty liver disease

Background

Mitochondrial dysfunction has been implicated as a significant factor in the liver disease process. Blueberry juice and probiotics (BP) synergistically improve liver function in alcoholic fatty liver disease (AFLD), although the mechanism for this effect was unclear. This study aims to investigate the effect and specific mechanisms of BP on AFLD.

Methods

C57/BL6 mice were randomly divided into seven groups: CG (control), MG (AFLD model), BJ (MG mice treated with blueberry), BJB (MG mice treated with BP), SI (AFLD mice treated with SIRT1 siRNA), BJSI (SI mice treated with blueberry), and BJBSI (SI mice treated with BP). The mice were fed an alcohol liquid diet for 10 days to establish the AFLD model, and subjected to BP and SIRT1 siRNA intervention for 10 days. Liver pathology was performed on day 11, and biochemical and molecular analyses of liver mitochondria were employed on day 12.

Results

BP significantly ameliorated hepatic mitochondrial injury, mitochondrial swelling, and hepatic necrosis in AFLD. BP alleviated hepatic mitochondrial dysfunction by increasing the expression of succinate dehydrogenase and cytochrome c oxidase, increasing respiratory control rate and the ADP/O ratio, and facilitating the synthesis of energy-related molecules. Besides, BP increased the expression of glutathione and superoxide dismutase, and inhibited malondialdehyde expression and reactive oxygen species activity. BP-induced sirtuin 1 (SIRT1), which activates peroxisome proliferator-activated receptor-gamma coactivator-1α, both of which mediate mitochondrial homeostasis. SIRT1 silencing suppressed the BP-induced changes in liver mitochondria, blunting its efficacy.

Conclusions

The ingredients of BP ameliorate hepatocyte mitochondrial dysfunction in AFLD mice.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-021-00554-3.

The interplay of microRNAs and transcription factors in autophagy regulation in nonalcoholic fatty liver disease

The autophagy-lysosomal degradation system has an important role in maintaining liver homeostasis by removing unnecessary intracellular components. Impaired autophagy has been linked to nonalcoholic fatty liver disease (NAFLD), which includes hepatitis, steatosis, fibrosis, and cirrhosis. Thus, gaining an understanding of the mechanisms that regulate autophagy and how autophagy contributes to the development and progression of NAFLD has become the focus of recent studies. Autophagy regulation has been thought to be primarily regulated by cytoplasmic processes; however, recent studies have shown that microRNAs (miRNAs) and transcription factors (TFs) also act as key regulators of autophagy by targeting autophagy-related genes. In this review, we summarize the miRNAs and TFs that regulate the autophagy pathway in NAFLD. We further focus on the transcriptional and posttranscriptional regulation of autophagy and discuss the complex regulatory networks involving these regulators in autophagy. Finally, we highlight the potential of targeting miRNAs and TFs involved in the regulation of autophagy for the treatment of NAFLD.

Fucoxanthin rescues dexamethasone induced C2C12 myotubes atrophy

Muscle atrophy and weakness are the adverse effects of long-term or high dose usage of glucocorticoids. In the present study, we explored the effects of fucoxanthin (10 μM) on dexamethasone (10 μM)-induced atrophy in C2C12 myotubes and investigated its underlying mechanisms. The diameter of myotubes was observed under a light microscope, and the expression of myosin heavy chain (MyHC), proteolysis-related, autophagy-related, apoptosis-related, and mitochondria-related proteins was analyzed by western blots or immunoprecipitation. Fucoxanthin alleviates dexamethasone-induced muscle atrophy in C2C12 myotubes, indicated by increased myotubes diameter and expression of MyHC, decreased expression of muscle atrophy F-box (Atrogin-1) and muscle ring finger 1 (MuRF1). Through activating SIRT1, fucoxanthin inhibits forkhead box O (FoxO) transcriptional activity to reduce protein degradation, induces autophagy to enhance degraded protein clearance, promotes mitochondrial function and diminishes apoptosis. In conclusion, we identified fucoxanthin ameliorates dexamethasone induced C2C12 myotubes atrophy through SIRT1 activation.

Key Signaling Pathways in Aging and Potential Interventions for Healthy Aging

Aging is a fundamental biological process accompanied by a general decline in tissue function. Indeed, as the lifespan increases, age-related dysfunction, such as cognitive impairment or dementia, will become a growing public health issue. Aging is also a great risk factor for many age-related diseases. Nowadays, people want not only to live longer but also healthier. Therefore, there is a critical need in understanding the underlying cellular and molecular mechanisms regulating aging that will allow us to modify the aging process for healthy aging and alleviate age-related disease. Here, we reviewed the recent breakthroughs in the mechanistic understanding of biological aging, focusing on the adenosine monophosphate-activated kinase (AMPK), Sirtuin 1 (SIRT1) and mammalian target of rapamycin (mTOR) pathways, which are currently considered critical for aging. We also discussed how these proteins and pathways may potentially interact with each other to regulate aging. We further described how the knowledge of these pathways may lead to new interventions for antiaging and against age-related disease.

Sirt1 coordinates with ERα to regulate autophagy and adiposity

Sex difference in adiposity has long been recognized but the mechanism remains incompletely understood. Previous studies suggested that adiposity was regulated by autophagy in response to energy status change. Here, we show that the energy sensor Sirt1 mediates sex difference in adiposity by regulating autophagy and adipogenesis in partnership with estrogen receptor α (ERα). Autophagy and adipogenesis were suppressed by Sirt1 activation or overexpression, which was associated with reduced sex difference in adiposity. Mechanistically, Sirt1 deacetylated and activated AKT and STAT3, resulting in suppression of autophagy and adipogenesis via mTOR-ULK1 and p55 cascades. ERα induced Sirt1 expression and inhibited autophagy in adipocytes, while silencing Sirt1 reversed the effects of ERα on autophagy and promoted adipogenesis. Moreover, Sirt1 deacetylated ERα, which constituted a positive feedback loop in the regulation of autophagy and adiposity. Our results revealed a new mechanism of Sirt1 regulating autophagy in adipocytes and shed light on sex difference in adiposity.

Ferulic acid alleviates lipotoxicity-induced hepatocellular death through the SIRT1-regulated autophagy pathway and independently of AMPK and Akt in AML-12 hepatocytes

Background

Lipotoxicity-induced cell death plays a detrimental role in the pathogenesis of metabolic diseases. Ferulic acid, widespread in plant-based food, is a radical scavenger with multiple bioactivities. However, the benefits of ferulic acid against hepatic lipotoxicity are largely unclear. Here, we investigated the protective effect of ferulic acid against palmitate-induced lipotoxicity and clarified its potential mechanisms in AML-12 hepatocytes.

Methods

AML-12 mouse hepatocytes were exposed to palmitate to mimic lipotoxicity. Different doses (25, 50, and 100 μM) of ferulic acid were added 2 h before palmitate treatment. Cell viability was detected by measuring lactate dehydrogenase release, nuclear staining, and the expression of cleaved-caspase-3. Intracellular reactive oxygen species content and mitochondrial membrane potential were analysed by fluorescent probes. The potential mechanisms were explored by molecular biological methods, including Western blotting and quantitative real-time PCR, and were further verified by siRNA interference.

Results

Our data showed that ferulic acid significantly inhibited palmitate-induced cell death, rescued mitochondrial membrane potential, reduced reactive oxygen species accumulation, and decreased inflammatory factor activation, including IL-6 and IL-1beta. Ferulic acid significantly stimulated autophagy in hepatocytes, whereas autophagy suppression blocked the protective effect of ferulic acid against lipotoxicity. Ferulic acid-activated autophagy, which was triggered by SIRT1 upregulation, was mechanistically involved in its anti-lipotoxicity effects. SIRT1 silencing blocked most beneficial changes induced by ferulic acid.

Conclusions

We demonstrated that the phytochemical ferulic acid, which is found in plant-based food, protected against hepatic lipotoxicity, through the SIRT1/autophagy pathway. Increased intake of ferulic acid-enriched food is a potential strategy to prevent and/or improve metabolic diseases with lipotoxicity as a typical pathological feature.

SIRT1 reduces epigenetic and non-epigenetic changes to maintain the quality of postovulatory aged oocytes in mice

Postovulatory oocyte aging has a major influence on the development potential of embryos. Many antioxidants can delay oocyte aging by regulating the expression of SIRT1. However, there is a lack of knowledge on SIRT1 function in postovulatory oocyte aging. In vitro transcribed RNA of Sirt1 was injected into fresh oocytes to investigate the function of SIRT1 during postovulatory oocyte aging. In the present study, SIRT1 was found to be down-regulated in aged oocytes compared with fresh oocytes. Meanwhile the intensity of acetylation of H3K9 (H3K9ac) and H3K4 methylation increased in postovulatory aged oocytes. After the oocytes were injected with SIRT1 and aged for 12 h, the intensity of H3K9ac and H3K4 methylation markedly decreased compared with controls. Furthermore, SIRT1 overexpression also reduced the aging-induced oocyte morphological changes and reactive oxygen species accumulation, maintained the spindle normal morphology and attenuated the aging-associated abnormalities of mitochondrial function. The role of SIRT1 in protecting oocyte aging was diminished when oocytes with overexpressed SIRT1 were cultured with SIRT1 inhibitor EX-527. Briefly, these present results show that SIRT1 not only reduced the non-epigenetic changes such as abnormal oocyte morphology, ROS accumulation, spindle defects and mitochondrial dysfunctions but also regulated the epigenetic changes in order to maintain the quality of postovulatory aged oocytes.

Targeting the core of neurodegeneration: FoxO, mTOR, and SIRT1

The global increase in lifespan noted not only in developed nations, but also in large developing countries parallels an observed increase in a significant number of non-communicable diseases, most notable neurodegenerative disorders. Neurodegenerative disorders present a number of challenges for treatment options that do not resolve disease progression. Furthermore, it is believed by the year 2030, the services required to treat cognitive disorders in the United States alone will exceed $2 trillion annually. Mammalian forkhead transcription factors, silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae), the mechanistic target of rapamycin, and the pathways of autophagy and apoptosis offer exciting avenues to address these challenges by focusing upon core cellular mechanisms that may significantly impact nervous system disease. These pathways are intimately linked such as through cell signaling pathways involving protein kinase B and can foster, sometimes in conjunction with trophic factors, enhanced neuronal survival, reduction in toxic intracellular accumulations, and mitochondrial stability. Feedback mechanisms among these pathways also exist that can oversee reparative processes in the nervous system. However, mammalian forkhead transcription factors, silent mating type information regulation 2 homolog 1, mechanistic target of rapamycin, and autophagy can lead to cellular demise under some scenarios that may be dependent upon the precise cellular environment, warranting future studies to effectively translate these core pathways into successful clinical treatment strategies for neurodegenerative disorders.

SIRT1: Mechanism and Protective Effect in Diabetic Nephropathy

Diabetic nephropathy (DN) is referred to as the microvascular complication of the kidneys induced by insufficient production of insulin or an ineffective cellular response to insulin, and is the main cause of end-stage renal disease. Currently, available therapies provide only symptomatic relief and fail to improve the outcome of diabetic nephropathy. Studies on diabetic animals had shown overexpression of SIRT1 in both podocytes and renal tubular cells attenuated proteinuria and kidney injury in the animal model of DN. Sirt1 exerts renoprotective effects in DKD in part through the deacetylation of transcription factors involved in the disease pathogenesis, such as NF-кB, Smad3, FOXO and p53. The purpose of this review is to highlight the protective mechanism of SIRT1 involved in the pathogenesis of diabetic nephropathy.

Modulatory Effects of Autophagy on APP Processing as a Potential Treatment Target for Alzheimer's Disease

Alzheimer’s disease (AD) is characterized by the formation of intracellular aggregate composed of heavily phosphorylated tau protein and extracellular deposit of amyloid-β (Aβ) plaques derived from proteolysis cleavage of amyloid precursor protein (APP). Autophagy refers to the lysosomal-mediated degradation of cytoplasmic constituents, which plays a critical role in maintaining cellular homeostasis. Importantly, recent studies reported that dysregulation of autophagy is associated in the pathogenesis of AD, and therefore, autophagy modulation has gained attention as a promising approach to treat AD pathogenesis. In AD, both the maturation of autolysosomes and its retrograde transports have been obstructed, which causes the accumulation of autophagic vacuoles and eventually leads to degenerating and dystrophic neurites function. However, the mechanism of autophagy modulation in APP processing and its pathogenesis have not yet been fully elucidated in AD. In the early stage of AD, APP processing and Aβ accumulation-mediated autophagy facilitate the removal of toxic protein aggregates via mTOR-dependent and -independent pathways. In addition, a number of autophagy-related genes (Atg) and APP are thought to influence the development of AD, providing a bidirectional link between autophagy and AD pathology. In this review, we summarized the current observations related to autophagy regulation and APP processing in AD, focusing on their modulation associated with the AD progression. Moreover, we emphasizes the application of small molecules and natural compounds to modulate autophagy for the removal and clearance of APP and Aβ deposits in the pathological condition of AD.

SIRT1 suppresses burn injury-induced inflammatory response through activating autophagy in RAW264.7 macrophages

The present study sought to investigate the association between silent information regulator 1 (SIRT1) and autophagy during systemic inflammatory response syndrome following burn injury. The experimental burn model in mice and macrophages were established. SIRT1 mRNA expression was quantified by quantitative real-time PCR. The protein levels of SIRT1 and the conversion of light chain 3 (LC3)-I to LC3-II were determined by western blot analysis. The formation of autophagosomes was assessed by green fluorescence protein-tagged LC3 fluorescence. The contents of inflammatory cytokines interleukin (IL)-1, IL-6, IL-10 and IL-18 were measured by ELISA. SIRT1 was highly expressed in burned tissues and RAW264.7 cells treated with serum obtained from mice with burn injuries. Moreover, SIRT1 overexpression augmented, whereas sirtinol, an inhibitor of SIRT1, attenuated burn injury-induced increasing number of autophagosomes and expression levels of LC3-II/LC3-I in RAW264.7 cells. Besides, sirtinol effectively prevented SIRT1-induced pro-inflammation during burn injury. Furthermore, autophagy inhibition by 3-methyladenine significantly attenuated SIRT1 overexpression-mediated pro-inflammatory cytokine production. SIRT1 abolished burn injury-induced inflammatory response by inducing autophagy.

Replicative Senescence and Expression of Autophagy Genes in Mesenchymal Stromal Cells

Cell senescence leads to a number of changes in the properties of mesenchymal stromal cells (MSCs). In particular, the number of damaged structures is increased producing negative effect on intracellular processes. Elimination of the damaged molecules and organelles occurs via autophagy that can be important in the context of aging. Cultivation under low oxygen level can be used as an approach for enhancement of MSC therapeutic properties and "slowing down" cell senescence. The goal of this work was to study some morphological and functional characteristics and expression of autophagy-associated genes during replicative senescence of MSCs under different oxygen concentration. The study revealed changes in the regulation of autophagy at the transcriptional level. Upregulation of the expression of autophagosome membrane growth genes ATG9A and ULK1, of the autophagosome maturation genes CTSD, CLN3, GAA, and GABARAPL1, of the autophagy regulation genes TP53, TGFB1, BCL2L1, FADD, and HTT was shown. These changes were accompanied by downregulation of IGF1 and TGM2 expression. Increase of the lysosomal compartment volume was observed in the senescent MSCs that also indicated increase of their degradation activity. The number of lysosomes was decreased following prolonged cultivation under low oxygen concentration (5%). The replicative senescence of MSCs under conditions of different oxygen levels led to the similar modifications in the expression of the autophagy-associated genes.

Sirt1 attenuates diabetic keratopathy by regulating the endoplasmic reticulum stress pathway

AIMS

The objectives of this study were to explore physiological and pathological changes in the corneas of diabetic rats by intervening in the expression of silent information regulator 1 (Sirt1) and to investigate whether Sirt1 can regulate the activation of endoplasmic reticulum stress (ERS) while influencing corneal epithelial cell apoptosis under high glucose conditions.

MATERIALS AND METHODS

Using 8-week old Sprague-Dawley rats, we established a model of type 1 diabetes, with or without Sirt1 intervention. Clinical evaluation was performed once per week. Primary rat corneal epithelial cells (RCECs) were cultured by combining Sirt1 intervention under high glucose conditions. Generation of reactive oxygen species (ROS), apoptosis, and the expression of Sirt1 and ERS-related proteins were evaluated in rat corneal tissues and RCECs.

KEY FINDINGS

During the intervention, clinical evaluation of the ocular surface, ROS generation, apoptosis, and protein expression of ERS-related proteins in corneal tissue and cultured RCECs were altered with Sirt1expression levels.

SIGNIFICANCE

Sirt1 expression influences the pathological progression of diabetic keratopathy, plays an important role in regulating the ERS pathway, and decreases corneal epithelial cell apoptosis.

Autophagy and Redox Homeostasis in Parkinson's: A Crucial Balancing Act

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are generated primarily from endogenous biochemical reactions in mitochondria, endoplasmic reticulum (ER), and peroxisomes. Typically, ROS/RNS correlate with oxidative damage and cell death; however, free radicals are also crucial for normal cellular functions, including supporting neuronal homeostasis. ROS/RNS levels influence and are influenced by antioxidant systems, including the catabolic autophagy pathways. Autophagy is an intracellular lysosomal degradation process by which invasive, damaged, or redundant cytoplasmic components, including microorganisms and defunct organelles, are removed to maintain cellular homeostasis. This process is particularly important in neurons that are required to cope with prolonged and sustained operational stress. Consequently, autophagy is a primary line of protection against neurodegenerative diseases. Parkinson's is caused by the loss of midbrain dopaminergic neurons (mDANs), resulting in progressive disruption of the nigrostriatal pathway, leading to motor, behavioural, and cognitive impairments. Mitochondrial dysfunction, with associated increases in oxidative stress, and declining proteostasis control, are key contributors during mDAN demise in Parkinson's. In this review, we analyse the crosstalk between autophagy and redoxtasis, including the molecular mechanisms involved and the detrimental effect of an imbalance in the pathogenesis of Parkinson's.

Mogroside IIIE Alleviates High Glucose-Induced Inflammation, Oxidative Stress and Apoptosis of Podocytes by the Activation of AMPK/SIRT1 Signaling Pathway

BACKGROUND

Diabetic nephropathy (DN) is the leading cause of impaired renal function. The purpose of this study was to investigate the effects of Mogroside IIIE (MG IIIE), a cucurbitane-type compound isolated from Siraitia grosvenorii, in high glucose (HG)-induced podocytes and the possible mechanisms.

METHODS

MPC-5 cells were cultured under normal glucose or HG conditions. After treatment with MG IIIE, cell viability was examined using a cell counting kit-8 assay. The contents of inflammatory factors and oxidative stress-related markers were determined using the corresponding kits. Additionally, apoptosis of MPC-5 cells was determined using flow cytometry assay and the levels of apoptosis-associated proteins were evaluated by Western blot analysis. Moreover, the expression of proteins in AMPK/SIRT1 signaling was tested and the compound C, an AMPK inhibitor, was used to study whether the effects of MG IIIE on HG-induced MPC-5 cells were mediated by activation of the AMPK/SIRT1 signaling pathway.

RESULTS

MG IIIE elevated the cell viability of HG-induced MPC-5 cells, reduced the concentrations of inflammatory cytokines and decreased the levels of oxidative stress-related markers. What's more, the apoptosis of podocytes induced by HG was inhibited after MG IIIE intervention, accompanied by the upregulated expression of Bcl-2 and downregulated expression of Bax, cleaved caspase-3 and cleaved caspase-9. It was also found that MG IIIE could activate the AMPK/SIRT1 signaling, but compound C inhibited this pathway and reversed the inhibitory effects of MG IIIE on inflammation, oxidative stress and apoptosis in HG-stimulated podocytes.

CONCLUSION

MG IIIE can alleviate HG-induced inflammation and oxidative stress of podocytes by the activation of AMPK-SIRT1 signaling.

Desoxyrhapontigenin attenuates neuronal apoptosis in an isoflurane-induced neuronal injury model by modulating the TLR-4/cyclin B1/Sirt-1 pathway

This study investigated the protective effect of desoxyrhapontigenin (DOP) against isoflurane (ISF)-induced neuronal injury in rats. Neuronal injury was induced in pups by exposing them to 0.75% ISF on postnatal day 7 with 30% oxygen for 6 h. The pups were treated with DOP 10 mg/kg, i.p., for 21 days after ISF exposure. The protective effect of DOP was estimated by assessing cognitive function using the neurological score and the Morris water maze. Neuronal apoptosis was assessed in the hippocampus using the TUNEL assay, and protein expression of caspase-3, Bax, and Bcl-2 was measured by Western blotting. The levels of cytokines and oxidative stress parameters were assessed by ELISA. Western blotting and RT-PCR were performed to measure the expression of NF-kB, TLR-4, Sirt-1, and cyclin B1 protein in the brain. The cognitive function and neurological function scores were improved in the DOP group compared with the ISF group. Moreover, DOP treatment reduced the number of TUNEL-positive cells and the expression of caspase-3, Bax, and Bcl-2 protein in the brains of rats with neuronal injury. The levels of mediators of inflammation and oxidative stress were reduced in the brain tissue of the DOP group. Treatment with DOP attenuated the protein expression of TLR-4, NF-kB, cyclin B1, and Sirt-1 in the brain tissue of rats with neuronal injury. In conclusion, DOP ameliorates neuronal apoptosis and improves cognitive function in rats with ISF-induced neuronal injury. Moreover, DOP treatment can prevent neuronal injury by regulating the TLR-4/cyclin B1/Sirt-1 pathway.

Hypoxia Helps Maintain Nucleus Pulposus Homeostasis by Balancing Autophagy and Apoptosis

Intervertebral disc degeneration (IVDD) is a common cause of lower back pain. Programmed cell death (PCD) including apoptosis and autophagy is known to play key mechanistic roles in the development of IVDD. We hypothesized that the nucleus pulposus cells that make up the center of the IVD can be affected by aging and environmental oxygen concentration, thus affecting the development of IVDD. Here, we evaluated the phenotype changes and PCD signaling in nucleus pulposus cells in two different oxygen percentages (5% (hypoxia) and 20% (normoxia)) up to serial passage 20. NP cells were isolated from the lumbar discs of rats, and the chondrogenic, autophagic, and apoptotic gene expressions were analyzed during cell culture up to serial passage 20. Hypoxia significantly increased the number of autophagosomes, as determined by monodansylcadaverine staining and transmission electron microscopy. Furthermore, hypoxia triggered the activation of autophagic flux (beclin-1, LC3-II/LC3-I ratio, and SIRT1) with a concomitant decrease in the expression of apoptotic proteins (Bax and caspase-3). Despite injury and age differences, no significant differences were observed between the ex vivo lumbar disc cultures of groups incubated in the hypoxic chamber. Our study provides a better understanding of autophagy- and apoptosis-related senescence in NP cells. These results also provide insight into the effects of aging on NP cells and their PCD levels during aging.

Heme Oxygenase-1 in liver transplant ischemia-reperfusion injury: From bench-to-bedside

Hepatic ischemia-reperfusion injury (IRI), a major risk factor for early allograft dysfunction (EAD) and acute or chronic graft rejection, contributes to donor organ shortage for life-saving orthotopic liver transplantation (OLT). The graft injury caused by local ischemia (warm and/or cold) leads to parenchymal cell death and release of danger-associated molecular patterns (DAMPs), followed by reperfusion-triggered production of reactive oxygen species (ROS), activation of inflammatory cells, hepatocellular damage and ultimate organ failure. Heme oxygenase 1 (HO-1), a heat shock protein-32 induced under IR-stress, is an essential component of the cytoprotective mechanism in stressed livers. HO-1 regulates anti-inflammatory responses and may be crucial in the pathogenesis of chronic diseases, such as arteriosclerosis, hypertension, diabetes and steatosis. An emerging area of study is macrophage-derived HO-1 and its pivotal intrahepatic homeostatic function played in IRI-OLT. Indeed, ectopic hepatic HO-1 overexpression activates intracellular SIRT1/autophagy axis to serve as a key cellular self-defense mechanism in both mouse and human OLT recipients. Recent translational studies in rodents and human liver transplant patients provide novel insights into HO-1 mediated cytoprotection against sterile hepatic inflammation. In this review, we summarize the current bench-to-bedside knowledge on HO-1 molecular signaling and discuss their future therapeutic potential to mitigate IRI in OLT.

Combined pre-conditioning with salidroside and hypoxia improves proliferation, migration and stress tolerance of adipose-derived stem cells

Oxidative stress after ischaemia impairs the function of transplanted stem cells. Increasing evidence has suggested that either salidroside (SAL) or hypoxia regulates growth of stem cells. However, the role of SAL in regulating function of hypoxia‐pre–conditioned stem cells remains elusive. Thus, this study aimed to determine the effect of SAL and hypoxia pre‐conditionings on the proliferation, migration and tolerance against oxidative stress in rat adipose‐derived stem cells (rASCs). rASCs treated with SAL under normoxia (20% O₂) or hypoxia (5% O₂) were analysed for the cell viability, proliferation, migration and resistance against H₂O₂‐induced oxidative stress. In addition, the activation of Akt, Erk1/2, LC3, NF‐κB and apoptosis‐associated pathways was assayed by Western blot. The results showed that SAL and hypoxia treatments synergistically enhanced the viability (fold) and proliferation of rASCs under non‐stressed conditions in association with increased autophagic flux and activation of Akt, Erk1/2 and LC3. H₂O₂‐induced oxidative stress, cytotoxicity, apoptosis, autophagic cell death and NF‐κB activation were inhibited by SAL or hypoxia, and further attenuated by the combined SAL and hypoxia pre‐treatment. The SAL and hypoxia pre‐treatment also enhanced the proliferation and migration of rASCs under oxidative stress in association with Akt and Erk1/2 activation; however, the combined pre‐treatment exhibited a more profound enhancement in the migration than proliferation. Our data suggest that SAL combined with hypoxia pre‐conditioning may enhance the therapeutic capacity of ASCs in post‐ischaemic repair.

Downregulation of CDK5 Restores Sevoflurane-Induced Cognitive Dysfunction by Promoting SIRT1-Mediated Autophagy

An increasing number of studies have found that use of traditional anesthetics may lead to cognitive impairment of the immature brain. Our previous studies verified that cyclin-dependent kinase 5 (CDK5) plays a role in sevoflurane-induced cognitive dysfunction. Autophagy was shown to protect against anesthesia-induced nerve injury. Therefore, the current study aimed to ascertain if autophagy participates in anesthesia-induced neurotoxicity. In this study, primary hippocampal neurons were isolated and utilized for experiments in vitro. We also performed in vivo experiments with 6-day-old wild-type mice treated with or without roscovitine (Rosc, a CDK5 inhibitor) or 3-methyladenine (3-Ma, an autophagy inhibitor) after exposure to sevoflurane. We used the Morris water maze to analyze cognitive function. Immunohistochemical staining was used to assess pathologic changes in the hippocampus. The results showed that suppressing CDK5 reversed sevoflurane-induced nerve cell apoptosis both in vivo and in vitro and demonstrated that inhibits CDK5 activation promoted Sirtuin 1 (Sirt1) expression, which functions importantly in induced autophagy activation. Suppression of Sirt1 expression inhibited the protective effect of Rosc on sevoflurane-induced nerve injury by inhibiting autophagy activation. Our in vivo experiments also found that pretreatment with 3-Ma attenuated the protective effect of Rosc on sevoflurane-induced nerve injury and cognitive dysfunction. We conclude that inhibits CDK5 activation restored sevoflurane-induced cognitive dysfunction by promoting Sirt1-mediated autophagy.

Mitochondrial Transfer as a Therapeutic Strategy Against Ischemic Stroke

Stroke is a debilitating disease that remains the second leading cause of death and disability worldwide. Despite accumulating knowledge of the disease pathology, treatments for stroke are limited, and clinical translation of the neuroprotective agents has not been a complete success. Accumulating evidence links mitochondrial dysfunction to brain impairments after stroke. Recent studies have implicated the important roles of healthy mitochondria in neuroprotection and neural recovery following ischemic stroke. New and convincing studies have shown that mitochondrial transfer to the damaged cells can help revive cells energetic in the recipient cells. Hence, mitochondrial transplantation has shown to replace impaired or dysfunctional mitochondria with exogenous healthy mitochondria after ischemic stroke. We highlight the potential of mitochondrial transfer by stem cells as a therapeutic strategy for the treatment of ischemic stroke. This review captures the recent advances in the mitochondrial transfer as a novel and promising treatment for ischemic stroke.

DFIQ, a Novel Quinoline Derivative, Shows Anticancer Potential by Inducing Apoptosis and Autophagy in NSCLC Cell and In Vivo Zebrafish Xenograft Models

Lung cancer is one of the deadliest cancers worldwide due to chemoresistance in patients with late-stage disease. Quinoline derivatives show biological activity against HIV, malaria, bacteriuria, and cancer. DFIQ is a novel synthetic quinoline derivative that induces cell death in both in vitro and in vivo zebrafish xenograft models. DFIQ induced cell death, including apoptosis, and the IC₅₀ values were 4.16 and 2.31 μM at 24 and 48 h, respectively. DFIQ was also found to induce apoptotic protein cleavage and DNA damage, reduce cell cycle-associated protein expression, and disrupt reactive oxygen species (ROS) reduction, thus resulting in the accumulation of superoxide radicals. Autophagy is also a necessary process associated with chemotherapy-induced cell death. Lysosome accumulation and lysosome-associated membrane protein-2 (LAMP2) depletion were observed after DFIQ treatment, and cell death induction was restored upon treatment with the autophagy inhibitor 3-methyladenine (3-MA). Nevertheless, ROS production was found to be involved in DFIQ-induced autophagy activation and LAMP2 depletion. Our data provide the first evidence for developing DFIQ for clinical usage and show the regulatory mechanism by which DFIQ affects ROS, autophagy, and apoptosis.

Autophagy in cardiovascular health and disease

Autophagy is a cellular housekeeping and quality control mechanism that is essential for homeostasis and survival. By virtue of this role, any perturbations to the flow of this process in cardiac or vascular cells can elicit harmful effects on the cardiovascular system, and subsequently affect whole organismal health. In this chapter, we summarize the preclinical evidence supporting the role of autophagy in sustaining cardiovascular health during homeostasis and disease. Furthermore, we discuss how autophagy activation by dietary, genetic and pharmaceutical interventions can be exploited to counteract common cardiovascular disorders, including atherosclerosis, coronary artery disease, diabetic cardiomyopathy, arrhythmia, chemotherapy-induced cardiotoxicity and heart failure.

Polyphenols as Caloric-Restriction Mimetics and Autophagy Inducers in Aging Research

It has been thought that caloric restriction favors longevity and healthy aging where autophagy plays a vital role. However, autophagy decreases during aging and that can lead to the development of aging-associated diseases such as cancer, diabetes, neurodegeneration, etc. It was shown that autophagy can be induced by mechanical or chemical stress. In this regard, various pharmacological compounds were proposed, including natural polyphenols. Apart from the ability to induce autophagy, polyphenols, such as resveratrol, are capable of modulating the expression of pro- and anti-apoptotic factors, neutralizing free radical species, affecting mitochondrial functions, chelating redox-active transition metal ions, and preventing protein aggregation. Moreover, polyphenols have advantages compared to chemical inducers of autophagy due to their intrinsic natural bio-compatibility and safety. In this context, polyphenols can be considered as a potential therapeutic tool for healthy aging either as a part of a diet or as separate compounds (supplements). This review discusses the epigenetic aspect and the underlying molecular mechanism of polyphenols as an anti-aging remedy. In addition, the recent advances of studies on NAD-dependent deacetylase sirtuin-1 (SIRT1) regulation of autophagy, the role of senescence-associated secretory phenotype (SASP) in cells senescence and their regulation by polyphenols have been highlighted as well. Apart from that, the review also revised the latest information on how polyphenols can help to improve mitochondrial function and modulate apoptosis (programmed cell death).

SIRT1-dependent mechanisms and effects of resveratrol for amelioration of muscle wasting in NASH mice

Background

In non-alcoholic steatohepatitis (NASH), muscle wasting was an aggravating factor for the progression of hepatic steatosis. This study explores the potential benefits of chronic treatment with resveratrol, a strong activator of SIRT1 on the muscle wasting of NASH mice.

Methods

In vivo and in vitro study, we evaluate the SIRT1-dependent mechanisms and effects of resveratrol administration for 6 weeks with high-fat-methionine and choline deficient diet-induced NASH mice and palmitate-pretreated C2C12 myoblast cells.

Results

Resveratrol treatment improved grip strength and muscle mass of limbs, increased running distance and time on exercise wheels in NASH mice. There is a negative correlation between muscular SIRT1 activity and 3-nitrotyrosine levels of NASH and NASH-resv mice. The SIRT1-dependent effect of muscle wasting was associated with the suppression of oxidative stress, upregulation of antioxidants, inhibition of protein degradation, activation of autophagy, suppression of apoptotic activity, upregulation of lipolytic genes and the reduction of fatty infiltration in limb muscles of NASH mice. In vitro, resveratrol alleviated palmitate acid-induced oxidative stress, lipid deposition, autophagy dysfunction, apoptotic signals, and subsequently reduced fusion index and myotube formation of C2C12 cells. The beneficial effects of resveratrol were abolished by EX527.

Conclusions

Our study suggests that chronic resveratrol treatment is a potential strategy for amelioration of hepatic steatosis and muscle wasting in NASH mouse model.

Supplementation of insulin-transferrin-sodium selenite in culture medium improves the hypothermic storage of bovine embryos produced in vitro

Hypothermic storage of gametes and embryos at 4 °C can be used as an alternative to cryopreservation, but hypothermic preservation can maintain embryo viability for a short duration only. This study investigated the effect of insulin-transferrin-sodium selenite (ITS) in embryo culture medium on hypothermic storage of bovine embryos at 4 °C. Day 7 bovine embryos were subjected to hypothermic storage in tissue culture medium 199 supplemented with 50% fetal bovine serum and 25 mM HEPES for different time durations. After recovery, the embryos were assessed for survival and hatching rate and gene and protein expression levels. Supplementation of embryo culture medium with ITS significantly increased (P < 0.05) the survival and hatching ability of blastocysts stored at 4 °C for 72 h compared to the control group (100% and 76.3% vs 68.5% and 40.5%, respectively). Furthermore, the beneficial effects of ITS on embryos were associated with greater (P < 0.05) total cell number per blastocyst and lesser apoptotic cells number. Moreover, embryos cultured in ITS had lower intracellular lipid content. The protein expression of sirt1 was greater (P < 0.05) in the ITS group, however, caspase3 protein expression was significantly lesser (P < 0.05) in the ITS group. Quantitative reverse transcription PCR indicated that the mRNA levels of SIRT1 and HSP70 were (P < 0.05) increased upon culture with ITS; however, the mRNA levels of the pro-apoptotic genes BAX and CASP3 were reduced (P < 0.05). Taken together, these data suggest that supplementation of embryo culture medium with ITS improves in vitro bovine embryo quality and survival following hypothermic storage.

Mitophagy and Its Contribution to Metabolic and Aging-Associated Disorders

Significance: Mitochondria are the cellular powerhouses for ATP synthesis through oxidative phosphorylation, and the centers for fatty acid β-oxidation, metabolite synthesis, reactive oxygen species production, innate immunity, and apoptosis. To fulfill these critical functions, mitochondrial quality and homeostasis must be well maintained. Abnormal mitochondrial quality contributes to aging and age-related disorders, such as metabolic syndrome, cancers, and neurodegenerative diseases. Recent Advances: Mitophagy is a cellular process that selectively removes damaged or superfluous mitochondria by autolysosomal degradation and is regarded as one of the major mechanisms responsible for mitochondrial quality control. Critical Issues: To date, distinct mitophagy pathways have been discovered, including receptor-mediated mitophagy and ubiquitin-dependent mitophagy. Emerging knowledge of these pathways shows that they play important roles in sensing mitochondrial stress and signaling for metabolic adaptations. Future Directions: Here, we provide a review on the molecular mechanisms for mitophagy and its interplay with cellular metabolism, with a particular focus on its role in metabolic and age-related disorders.

Vitamin D Deficiency and the Risk of Cerebrovascular Disease

Vitamin D deficiency has been clearly linked to major chronic diseases associated with oxidative stress, inflammation, and aging, including cardiovascular and neurodegenerative diseases, diabetes, and cancer. In particular, the cardiovascular system appears to be highly sensitive to vitamin D deficiency, as this may result in endothelial dysfunction and vascular defects via multiple mechanisms. Accordingly, recent research developments have led to the proposal that pharmacological interventions targeting either vitamin D deficiency or its key downstream effects, including defective autophagy and abnormal pro-oxidant and pro-inflammatory responses, may be able to limit the onset and severity of major cerebrovascular diseases, such as stroke and cerebrovascular malformations. Here we review the available evidence supporting the role of vitamin D in preventing or limiting the development of these cerebrovascular diseases, which are leading causes of disability and death all over the world.

Transcription Factor 4 Regulates the Regeneration of Corneal Endothelial Cells

Purpose

Human corneal endothelial cells (hCECs) have limited regenerative capacity in vivo. Reduced hCEC density results in bullous keratopathy requiring corneal transplantation. This study reveals the role of transcription factor 4 (TCF4) in hCEC diseases and suggests that TCF4 may be a molecular target for hCEC regeneration.

Methods

Cell shape, cell proliferation rates, and proliferation-associated proteins were evaluated in normal or senescent hCECs. TCF4 was blocked by siRNA (si-TCF4) or activated using clustered regularly interspaced short palindromic repeats (CRISPR)/dCas9 activation systems (pl-TCF4). The corneal endothelium of six-week-old Sprague-Dawley (SD) rats was transfected by electroporation followed by cryoinjury.

Results

Cell proliferation rates and TCF4 levels were reduced in senescent cells. TCF4 CRISPR activation enhanced corneal endothelial wound healing. TCF4 regulated mitochondrial functions including mitochondrial membrane potential, mitochondrial superoxide levels, and energy production. The percentage of cells in the S-phase was reduced with si-TCF4 and increased with pl-TCF4. Cell proliferation and cell cycle-associated proteins were regulated by TCF4. Autophagy was induced by si-TCF4. In vivo transfection of CRISPR/dCas9 activation systems (a-TCF4) induced regeneration of corneal endothelium.

Conclusions

Corneal endothelial diseases are associated with TCF4 reduction; TCF4 may be a potential target for hCEC diseases. Gene therapy using TCF4 CRISPR/dCas9 may be an effective treatment for hCEC diseases.

Epigenetic Control of Mitochondrial Function in the Vasculature

The molecular signatures of epigenetic regulation and chromatin architecture are emerging as pivotal regulators of mitochondrial function. Recent studies unveiled a complex intersection among environmental factors, epigenetic signals, and mitochondrial metabolism, ultimately leading to alterations of vascular phenotype and increased cardiovascular risk. Changing environmental conditions over the lifetime induce covalent and post-translational chemical modification of the chromatin template which sensitize the genome to establish new transcriptional programs and, hence, diverse functional states. On the other hand, metabolic alterations occurring in mitochondria affect the availability of substrates for chromatin-modifying enzymes, thus leading to maladaptive epigenetic signatures altering chromatin accessibility and gene transcription. Indeed, several components of the epigenetic machinery require intermediates of cellular metabolism (ATP, AcCoA, NADH, α-ketoglutarate) for enzymatic function. In the present review, we describe the emerging role of epigenetic modifications as fine tuners of gene transcription in mitochondrial dysfunction and vascular disease. Specifically, the following aspects are described in detail: (i) mitochondria and vascular function, (ii) mitochondrial ROS, (iii) epigenetic regulation of mitochondrial function; (iv) the role of mitochondrial metabolites as key effectors for chromatin-modifying enzymes; (v) epigenetic therapies. Understanding epigenetic routes may pave the way for new approaches to develop personalized therapies to prevent mitochondrial insufficiency and its complications.

Dissecting pharmacological effects of chloroquine in cancer treatment: interference with inflammatory signaling pathways

Chloroquines are 4-aminoquinoline-based drugs mainly used to treat malaria. At pharmacological concentrations, they have significant effects on tissue homeostasis, targeting diverse signaling pathways in mammalian cells. A key target pathway is autophagy, which regulates macromolecule turnover in the cell. In addition to affecting cellular metabolism and bioenergetic flow equilibrium, autophagy plays a pivotal role at the interface between inflammation and cancer progression. Chloroquines consequently have critical effects in tissue metabolic activity and importantly, in key functions of the immune system. In this article, we will review the work addressing the role of chloroquines in the homeostasis of mammalian tissue, and the potential strengths and weaknesses concerning their use in cancer therapy.

Deacetylation of LAMP1 drives lipophagy-dependent generation of free fatty acids by Abrus agglutinin to promote senescence in prostate cancer

Therapy-induced senescence in cancer cells is an irreversible antiproliferative state, which inhibits tumor growth and is therefore a potent anti-neoplastic mechanism. In this study, low doses of Abrus agglutinin (AGG)-induced senescence through autophagy in prostate carcinoma cells (PC3) and inhibited proliferation. The inhibition of autophagy with 3-methyl adenine reversed AGG-induced senescence, thus confirming that AGG-triggered senescence required autophagy. AGG treatment also led to lipophagy-mediated accumulation of free fatty acids (FFAs), with a concomitant decrease in the number of lipid droplets. Lalistat, a lysosomal acid lipase inhibitor, abrogated AGG-induced lipophagy and senescence in PC3 cells, indicating that lipophagy is essential for AGG-induced senescence. The accumulation of FFAs increased reactive oxygen species generation, a known facilitator of senescence, which was also reduced in the presence of lalistat. Furthermore, AGG upregulated silent mating type information regulator 2 homolog 1 (SIRT1), while the presence of sirtinol reduced autophagy flux and the senescent phenotype in the AGG-treated cells. Mechanistically, AGG-induced cytoplasmic SIRT1 deacetylated a Lys residue on the cytoplasmic domain of lysosome-associated membrane protein 1 (LAMP1), an autolysosomal protein, resulting in lipophagy and senescence. Taken together, our findings demonstrate a novel SIRT1/LAMP1/lipophagy axis mediating AGG-induced senescence in prostate cancer cells.

Regulation of Autophagy in Cells Infected With Oncogenic Human Viruses and Its Impact on Cancer Development

About 20% of total cancer cases are associated to infections. To date, seven human viruses have been directly linked to cancer development: high-risk human papillomaviruses (hrHPVs), Merkel cell polyomavirus (MCPyV), hepatitis B virus (HBV), hepatitis C virus (HCV), Epstein–Barr virus (EBV), Kaposi’s sarcoma-associated herpesvirus (KSHV), and human T-lymphotropic virus 1 (HTLV-1). These viruses impact on several molecular mechanisms in the host cells, often resulting in chronic inflammation, uncontrolled proliferation, and cell death inhibition, and mechanisms, which favor viral life cycle but may indirectly promote tumorigenesis. Recently, the ability of oncogenic viruses to alter autophagy, a catabolic process activated during the innate immune response to infections, is emerging as a key event for the onset of human cancers. Here, we summarize the current understanding of the molecular mechanisms by which human oncogenic viruses regulate autophagy and how this negative regulation impacts on cancer development. Finally, we highlight novel autophagy-related candidates for the treatment of virus-related cancers.

SIRT1 and aging related signaling pathways

Aging is a biological phenomenon in which the structure and function of organisms declining with the increasing of age. It has become a major risk factor of human diseases, including diabetes, cancers, cardiovascular diseases and neurodegenerative diseases. Silencing information regulator 2 related enzyme 1(sirtuin1, SIRT1) is an NAD⁺-dependent deacetylase, which has been reported to be involved in the regulation of cellular senescence and aging. The expression of SIRT1 is diminished with aging in mice. By contrast, increased expression of SIRT1 is sufficient to extend lifespan in yeast, caenorhabditis elegans and mice. In this review, the relationship between SIRT1 and aging and various signaling networks associated with aging, including NF-κB, AMPK, mTOR, P53, PGC1α, and FoxOs will be discussed. Meanwhile, the potential therapeutic strategies of targeting SIRT1 to anti-aging are also addressed.

Seminal SIRT1-oxidative stress relationship in infertile oligoasthenoteratozoospermic men with varicocele after its surgical repair

This work assessed seminal SIRT1-oxidative stress (OS) relationship in infertile oligoasthenoteratozoospermic (OAT) men after varicocele repair. Overall, thirty OAT men with varicocele were investigated. Inclusion criteria were infertile males (males who were unable to initiate a pregnancy within 1 year of regular unprotected intercourse), confirmed OAT and normal female factor. These cases were subjected to history taking, clinical checkup and semen analysis. In their semen, seminal SIRT1, malondialdehyde (MDA) and glutathione peroxidase (GPx) levels were assessed. These men were subjected to varicocele surgical repair and were followed up for 3 months. Post-operatively, the mean seminal SIRT1, GPx levels showed significant increases and the mean MDA level showed significant decrease compared to the pre-operative levels linked to improved sperm parameters. The mean seminal SIRT1, GPx, MDA levels showed more significant improvement in grade III varicocele cases compared to grade II cases after surgical repair. Seminal SIRT1 levels showed significant positive correlations with sperm concentration, sperm motility, sperm normal morphology, seminal GPx levels and a significant negative correlation with seminal MDA levels. It could be concluded that seminal SIRT1 is significantly decreased in infertile OAT men with varicocele after its surgical repair linked to improved sperm parameters as well as seminal OS.

The pROS of Autophagy in Neuronal Health

Autophagy refers to a set of catabolic pathways that together facilitate degradation of superfluous, damaged and toxic cellular components. The most studied type of autophagy, called macroautophagy, involves membrane mobilisation, cargo engulfment and trafficking of the newly formed autophagic vesicle to the recycling organelle, the lysosome. Macroautophagy responds to a variety of intra- and extra-cellular stress conditions including, but not limited to, pathogen intrusion, oxygen or nutrient starvation, proteotoxic and organelle stress, and elevation of reactive oxygen species (ROS). ROS are highly reactive oxygen molecules that can interact with cellular macromolecules (proteins, lipids, nucleic acids) to either modify their activity or, when released in excess, inflict irreversible damage. Although increased ROS release has long been recognised for its involvement in macroautophagy activation, the underlying mechanisms and the wider impact of ROS-mediated macroautophagy stimulation remain incompletely understood.

We therefore discuss the growing body of evidence that describes the variety of mechanisms modulated by ROS that trigger cytoprotective detoxification via macroautophagy. We outline the role of ROS in signalling upstream of autophagy initiation, by increased gene expression and post-translational modifications of transcription factors, and in the formation and nucleation of autophagic vesicles by cysteine modification of conserved autophagy proteins including ATG4B, ATG7 and ATG3. Furthermore, we review the effect of ROS on selective forms of macroautophagy, specifically on cargo recognition by autophagy receptor proteins p62 and NBR1 (neighbour of BRCA1) and the recycling of mitochondria (mitophagy), and peroxisomes (pexophagy). Finally, we highlight both, the standalone and mutual contributions of abnormal ROS signalling and macroautophagy to the development and progression of neurodegenerative diseases.

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ROS are messengers that modify protein activity by PTMs.

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ROS-mediated PTMs regulate activity and specificity of autophagy proteins.

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Increase in autophagy mediates rapid clearance of oxidised cargo and ROS sources.

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The importance of ROS-mediated autophagy is highlighted in neurodegeneration.

Cross-talk between autophagy and apoptosis regulates testicular injury/recovery induced by cadmium via PI3K with mTOR-independent pathway

Autophagy and apoptosis are two major modes of cell death. A balanced interplay between both is vital for phagocytic clearance of apoptotic testicular cells. Here, generating a SD rats model-treated with cadmium (Cd) to mimic environmental exposure on human, we show that autophagy and apoptosis present synchronous change trends in Cd-induced testicular injury/self-recovery. Further, the cross-talk of autophagy and apoptosis is investigated in four testicular cell lines (GC-1/GC-2/TM3/TM4 cells) respectively. Results reveal that Cd-exposure for five consecutive weeks induces reproductive toxicity in male rats. After one cycle of spermatogenesis within 8 weeks without Cd, toxic effects are ameliorated significantly. In vitro, we find that PI3K inhibitor 3-MA regulates apoptosis by inhibiting autophagy with mTOR-independent pathway in Cd-treated testicular cells. Conclusively, cross-talk between autophagy and apoptosis regulates testicular injury/recovery induced by Cd via PI3K with mTOR-independent pathway.

Hydrogen sulfide attenuates cigarette smoke-induced airway remodeling by upregulating SIRT1 signaling pathway

Airway remodeling is one of the characteristics for chronic obstructive pulmonary disease (COPD). The mechanism underlying airway remodeling is associated with epithelial-mesenchymal transition (EMT) in the small airways of smokers and patients with COPD. Sirtuin 1 (SIRT1) is able to reduce oxidative stress, and to modulate EMT. Here, we investigated the effects and mechanisms of hydrogen sulfide (H2S) on pulmonary EMT in vitro and in vivo. We found that H2S donor NaHS inhibited cigarette smoke (CS)-induced airway remodeling, EMT and collagen deposition in mouse lungs. In human bronchial epithelial 16HBE cells, NaHS treatment also reduced CS extract (CSE)-induced EMT, collagen deposition and oxidative stress. Mechanistically, NaHS upregulated SIRT1 expression, but inhibited activation of TGF-β1/Smad3 signaling in vivo and in vitro. SIRT1 inhibition by a specific inhibitor EX527 significantly attenuated or abolished the ability of NaHS to reverse the CSE-induced oxidative stress. SIRT1 inhibition also abolished the protection of NaHS against CSE-induced EMT. Moreover, SIRT1 activation attenuated CSE-induced EMT by modifying TGF-β1-mediated Smad3 transactivation. In conclusion, H2S prevented CS-induced airway remodeling in mice by reversing oxidative stress and EMT, which was partially ameliorated by SIRT1 activation. These findings suggest that H2S may have therapeutic potential for the prevention and treatment of COPD.

The NAD+-mitophagy axis in healthy longevity and in artificial intelligence-based clinical applications

Nicotinamide adenine dinucleotide (NAD+) is an important natural molecule involved in fundamental biological processes, including the TCA cycle, OXPHOS, β-oxidation, and is a co-factor for proteins promoting healthy longevity. NAD+ depletion is associated with the hallmarks of ageing and may contribute to a wide range of age-related diseases including metabolic disorders, cancer, and neurodegenerative diseases. One of the central pathways by which NAD+ promotes healthy ageing is through regulation of mitochondrial homeostasis via mitochondrial biogenesis and the clearance of damaged mitochondria via mitophagy. Here, we highlight the contribution of the NAD+-mitophagy axis to ageing and age-related diseases, and evaluate how boosting NAD+ levels may emerge as a promising therapeutic strategy to counter ageing as well as neurodegenerative diseases including Alzheimer's disease. The potential use of artificial intelligence to understand the roles and molecular mechanisms of the NAD+-mitophagy axis in ageing is discussed, including possible applications in drug target identification and validation, compound screening and lead compound discovery, biomarker development, as well as efficacy and safety assessment. Advances in our understanding of the molecular and cellular roles of NAD+ in mitophagy will lead to novel approaches for facilitating healthy mitochondrial homoeostasis that may serve as a promising therapeutic strategy to counter ageing-associated pathologies and/or accelerated ageing.

Role of SIRT1 in hematologic malignancies

Sirtuin 1 (SIRT1) is a protein deacetylase, which regulates various physiological activities by deacetylating different protein substrates. An increasing number of studies have revealed critical roles of SIRT1 in different aspects of cancers including metabolism, proliferation, genomic instability, and chemotherapy resistance. Depending on the protein targets in a certain oncogenic context, SIRT1 may play a unique role in each individual blood cancer subtype. Our previous work showed that activation of SIRT1 in primitive leukemia cells of acute myeloid leukemia (AML) and chronic myelogenous leukemia (CML) promotes disease maintenance. On the other hand, an SIRT1 agonist was shown to disrupt maintenance of myelodysplastic syndrome (MDS) stem cells and holds promise as a potential therapeutic approach. Herein, we present a concise summary of the different functions of SIRT1 in hematologic malignancies.

Quercetin supports cell viability and inhibits apoptosis in cardiocytes by down-regulating miR-199a

Hypoxia-caused cardiocytes insults are closely correlated with ectopic expression of genes, which might be modulated by microRNAs (miRs). Quercetin exhibits a profound protective function against hypoxic damages in cardiomyocytes. Here, we aimed to investigate a possible underpinning. H9c2 cells were pre-administrated using quercetin before hypoxia treatment. The damages were assessed using viability, apoptosis and alteration of proteins associated with apoptosis and adenosine monophosphate-activated protein (AMPK) pathway. Transfection was conducted to enforce overexpression of miR-199a or silence of sirtuin 1 (sirt1) which were confirmed by qRT-PCR. Sirt1 protein was quantified by immunoblotting. A luciferase reporter was exploited to confirm the target relationship between miR-199a and sirt1 3'-untranslated region (3'-UTR). We found quercetin mitigated hypoxia-caused viability reduction and apoptosis with restoring apoptosis-associated protein and rescuing phosphorylation of AMPK. Quercetin flattened hypoxia-evoked overexpression of miR-199a. miR-199a abrogated the protective effects of quercetin against hypoxia-elicited damages. Quercetin elevated sirt1 which was repressed by hypoxia, while this effect was slight in miR-199a-overexpressed cells. miR-199a negatively mediated sirt1 expression through directly binding its 3'-UTR. Further, quercetin facilitated the phosphorylation of AMPK by up-regulating sirt1. Collectively, quercetin participated in repressing miR-199a which negatively modulated sirt1. Mechanically, through activating AMPK, quercetin protected cardiomyocytes cells against hypoxia-caused insults. Highlights Quercetin ameliorates hypoxia-evoked apoptosis and blockage of AMPK phosphorylation; The elevated miR-199a level is eased by quercetin, which might be a protective mechanism; Quercetin restores sirt1 level by repressing miR-199a expression; By mediating miR-199a and sirt1, AMPK phosphorylation is fortified by quercetin.

SIRT1/PGC-1 pathway activation triggers autophagy/mitophagy and attenuates oxidative damage in intestinal epithelial cells

Oxidative stress leads to intestinal epithelial cells damage, which induces tight junction injury and systemic endogenous stress syndrome. The evidence suggests that SIRT1/PGC-1α pathway is closely associated with oxidative damage. However, the mechanism in protecting intestinal epithelial cells against oxidative stress dependant on autopahgy/mitophagy remains to be elucidated. In the current study, we investigated the functional role of SIRT1/PGC-1α pathway on regulation of autopahgy/mitophagy and tight junction protein expression underlying the oxidative dysfunction in porcine intestinal epithelial cells (IPEC-1). Results demonstrated that H₂O₂ exposure caused high accumulation of ROS, with a decrease of mitochondrial membrane potential and an inhibition of the tight junction molecules in IPEC-1 cells. Also, COX IV mRNA expression and SIRT1/PGC-1α pathway were suppressed. Autophagy and PINK1/Parkin dependant-mitophagy were activated following H₂O₂ treatment. Further research indicated that activation of SIRT1/PGC-1α pathway caused by specific activator SRT 1720 resulted in elevating autophagy/mitophagy related markers and SIRT1 inhibitor EX 527 reversed these effects. Additionally, SIRT1 activation significantly suppressed the ROS generation, leading to increase mitochondrial membrane potential and COX IV expression. Most importantly, the expression of tight junction molecules contributing to maintain intestinal barrier integrity was significantly up-regulated. Collectively, these findings indicated that autophagy/mitophagy elevation caused by SIRT1/PGC-1α pathway activation might be a protective mechanism to increase tight junction integrity against oxidative stress-mediated ROS production in IPEC-1 cells.

A combination of bovine serum albumin with insulin-transferrin-sodium selenite and/or epidermal growth factor as alternatives to fetal bovine serum in culture medium improves bovine embryo quality and trophoblast invasion by induction of matrix metalloproteinases

This study investigated the use of bovine serum albumin (BSA) plus insulin-transferrin-sodium selenite (ITS) and/or epidermal growth factor (EGF) as alternatives to fetal bovine serum (FBS) in embryo culture medium. The developmental ability and quality of bovine embryos were determined by assessing their cell number, lipid content, gene expression and cryotolerance, as well as the invasion ability of trophoblasts. The percentage of embryos that underwent cleavage and formed a blastocyst was higher (P<0.01) in medium containing ITS plus EGF and BSA than in medium containing FBS. Culture with ITS plus EGF and BSA also increased the hatching ability of blastocysts and the total cell number per blastocyst. Furthermore, the beneficial effects of BAS plus ITS and EGF on embryos were associated with a significantly reduced intracellular lipid content, which increased their cryotolerance. An invasion assay confirmed that culture with ITS plus EGF and BSA significantly improved the invasion ability of trophoblasts. Real-time quantitative polymerase chain reaction analysis showed that the mRNA levels of matrix metalloproteinase-2 (MMP2) and MMP9, acyl-CoA synthetase long-chain family member 3, acyl-coenzyme A dehydrogenase long-chain and hydroxymethylglutaryl-CoA reductase significantly increased upon culture with ITS plus EGF and BSA. Moreover, protein expression levels of matrix metalloproteinase-2 and -9 increased (P<0.01) in medium supplemented with ITS plus EGF and BSA compared with medium supplemented with FBS. Taken together, these data suggest that supplementation of medium with ITS plus EGF and BSA improves invitro bovine embryo production, cryotolerance and invasion ability of trophoblasts.

SIRT1 Protects Against Apoptosis by Promoting Autophagy in the Oxygen Glucose Deprivation/Reperfusion-Induced Injury

Silent information regulator 1 (SIRT1) contributes to cellular regulation. Previous studies have reported SIRT1 to be abnormally expressed in the ischemic penumbra of cerebral ischemia/reperfusion (I/R) injury rat model. We investigated the effect of SIRT1 on oxygen and glucose deprivation/reperfusion (OGD/R) cell injury. Over-expressed or silenced SIRT1 pheochromocytoma 12 (PC12) cells were exposed to an in-vitro OGD/R injury. Western blot, TUNEL staining and immunofluorescence analyses were performed to assess apoptosis and autophagy. We found autophagy and apoptosis to be up-regulated and down-regulated, respectively, following the over-expression of SIRT1 in the OGD/R-induced PC12 cells. We also found the silencing of SIRT1 to culminate in the down-regulation and up-regulation of autophagy and apoptosis, respectively. On the basis of our results, we surmise that SIRT1 can promote autophagy and inhibit apoptosis in-vitro, and thus exhibit potential neuroprotection against OGD/R-induced injury. This could facilitate in the development of therapeutic approaches for cerebral I/R injury.

Autophagy inhibits the mesenchymal stem cell aging induced by D-galactose through ROS/JNK/p38 signalling

Autophagy and cellular senescence are two critical responses of mammalian cells to stress and may have a direct relationship given that they respond to the same set of stimuli, including oxidative stress, DNA damage, and telomere shortening. Mesenchymal stem cells (MSCs) have emerged as reliable cell sources for stem cell transplantation and are currently being tested in numerous clinical trials. However, the effects of autophagy on MSC senescence and corresponding mechanisms have not been fully evaluated. Several studies demonstrated that autophagy level increases in aging MSCs and the downregulation of autophagy can delay MSC senescence, which is inconsistent with most studies that showed autophagy could play a protective role in stem cell senescence. To further study the relationship between autophagy and MSC senescence and explore the effects and mechanisms of premodulated autophagy on MSC senescence, we induced the up- or down-regulation of autophagy by using rapamycin (Rapa) or 3-methyladenine, respectively, before MSC senescence induced by D-galactose (D-gal). Results showed that pretreatment with Rapa for 24 hours remarkably alleviated MSC aging induced by D-gal and inhibited ROS generation. p-Jun N-terminal kinases (JNK) and p-38 expression were also clearly decreased in the Rapa group. Moreover, the protective effect of Rapa on MSC senescence can be abolished by enhancing the level of ROS, and p38 inhibitor can reverse the promoting effect of H₂ O₂ on MSC senescence. In summary, the present study indicates that autophagy plays a protective role in MSC senescence induced by D-gal, and ROS/JNK/p38 signalling plays an important mediating role in autophagy-delaying MSC senescence.

QiDiTangShen Granules Activate Renal Nutrient-Sensing Associated Autophagy in db/db Mice

QiDiTangShen granules (QDTS) have been proven to reduce the proteinuria in patients with diabetic nephropathy (DN) effectively. The present study was aimed to investigate the mechanism underlying QDTS's renoprotection. The main components of QDTS were identified by ultra-high liquid chromatography-tandem mass spectrometry and pharmacological databases, among which active components were screened by oral bioavailability and drug-likeness. Their regulation on autophagy-related nutrient-sensing signal molecules (AMPK, SIRT1, and mTOR) was retrieved and analyzed through the Pubmed database. Then, db/db mice were randomly divided into three groups (model control, valsartan and QDTS), and given intragastric administration for 12 weeks, separately. Fasting and random blood glucose, body weight, urinary albumin excretion (UAE) and injury markers of liver and kidney were investigated to evaluate the effects and safety. Renal histological lesions were assessed, and the expressions of proteins related to nutrient-sensing signals and autophagy were investigated. Thirteen active components were screened from 78 components identified. Over half the components had already been reported to improve nutrient-sensing signals. QDTS significantly reduced UAE, ameliorated mesangial matrix deposition, alleviate the expression of protein and mRNA of TGF-β, α-SMA, and Col I, as well as improved the quality of mitochondria and the number of autophagic vesicles of renal tubular cells although the blood glucose was not decreased in db/db mice. Compared to the db/db group, the expression of the autophagy-inducible protein (Atg14 and Beclin1) and microtubule-associated protein 1 light chain 3-II (LC3-II) were up-regulated, autophagic substrate transporter p62 was down-regulated in QDTS group. It was also found that the expression of SIRT1 and the proportion of p-AMPK (thr172)/AMPK were increased, while the p-mTOR (ser2448)/mTOR ratio was decreased after QDTS treatment in db/db mice, which was consistent with the effect of its active ingredients on the nutrient-sensing signal pathway as reported previously. Therefore, QDTS may prevent the progression of DN by offering the anti-fibrotic effect. The renoprotection is probably attributable to the regulation of nutrient-sensing signal pathways, which activates autophagy.

Role of liraglutide in brain repair promotion through Sirt1-mediated mitochondrial improvement in stroke

Brain repair, especially axonal sprouting, is critical to restore motor function in disabled stroke patients. Liraglutide (LG) is a new kind of long-acting analogue of glucagon-like peptide-1 (GLP-1) and has potential protective effects in stroke. The mitochondria participate in brain repair after cerebral injury. However, the mechanism of the effect of LG on brain repair and its potential influence on mitochondria in stroke remains obscure. Here, in focal cerebral cortical ischemic mice model, LG improved the motor functional recovery and promoted axonal sprouting by restoring the activities of isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and succinate dehydrogenase. Moreover, LG remarkably increased the cell survival rate and revived the NeuN and GAP-43 levels in cortical neurons under hydrogen peroxide (H₂ O₂ ) exposure. It was also observed that LG reduced the generation of reactive oxygen species, stabilized the mitochondrial membrane potential, enhanced the levels of adenosine triphosphate, enhanced activities of mitochondrial complex-I, and decreased protein expression levels of fission-1 in H₂ O₂ -injured cortical neurons. Additionally, LG suppressed the expressions of sirtuin 1 (Sirt1) in cortical neurons exposed to H₂ O₂ . Furthermore, knockdown of Sirt1 by short interfering RNA facilitated the LG-mediated mitochondrial protection in cortical neurons under H₂ O₂ . Collectively, this data from the present study illustrated that LG exerted a promoting influence on brain repair, after cerebral ischemic injury, through Sirt1-mediated mitochondrial improvement.

Curcumin ameliorates chronic obstructive pulmonary disease by modulating autophagy and endoplasmic reticulum stress through regulation of SIRT1 in a rat model

Objectives

The ability of curcumin to activate SIRT1 and thereby promote autophagy and inhibit endoplasmic reticulum stress (ERS) in chronic obstructive pulmonary disease (COPD) remains unclear. We investigated the relationship between curcumin and SIRT1 activation in relation to autophagy and ERS in COPD.

Methods

We developed a rat COPD model by cigarette smoke exposure, and divided the rats into control, COPD, COPD + low-dose curcumin (50 mg/kg), COPD + medium-dose curcumin (100 mg/kg), COPD + high-dose curcumin (150 mg/kg), and COPD + high-dose curcumin + sirtinol (2 mM, 30 μL/kg) groups. Apoptosis was detected by TUNEL assay. SIRT1 gene and protein expression, and protein expression of autophagy-related genes LC3-I, LC3-II, and Beclin1, and ERS-related genes CHOP and GRP78 were measured by reverse transcription-polymerase chain reaction and western blot.

Results

SIRT1, LC3-I, LC3-II, and Beclin1 expression were significantly decreased and CHOP and GRP78 were enhanced in COPD compared with control rats. Curcumin increased the expression of SIRT1, LC3-I, LC3-II, and Beclin1 and decreased the expression of CHOP and GRP78 in COPD rats. The alleviating effects of curcumin on COPD in the SIRT1-inhibition group were reversed by suppressing LC3-I, LC3-II, and Beclin1 and increasing CHOP and GRP78.

Conclusion

Curcumin might alleviate COPD by promoting autophagy and inhibiting ERS through SIRT1 activation.