Sirt1 is essential for resveratrol enhancement of hypoxia-induced autophagy in the type 2 diabetic nephropathy rat

Overexpression of miR-138-5p suppresses MnCl2 -induced autophagy by targeting SIRT1 in SH-SY5Y cells

The mechanism of manganism caused by manganese (Mn), an important environmental risk factor for Parkinson's disease, is still unclear. Recent evidence suggested that autophagy participated in neurodegenerative diseases, in which microRNA played a crucial role. However, roles of microRNA in the aberrant autophagy that occurs in neurodegenerative diseases remains controversial. In nervous system, miRNA-138-5p is highly expressed and plays a key role in regulating memory and axon regeneration. Importantly, we also found that miR-138-5p expression decreased significantly after SH-SY5Y cells exposed to manganese chloride (MnCl₂ ) in previous study. To explore the role of miR-138-5p in Mn-induced autophagy, autophagy associated indicators were detected. And we found that MnCl₂ could induce autophagic dysregulation and inhibit expression of miR-138-5p. While the levels of LC3-II/LC3-I, Beclin1, and p62, the number of autophagosome formation significantly decreased after miR-138-5p over-expression, which demonstrated that miR-138-5p could clearly retard Mn-induced autophagy. In additional, we found there were classical and evolutionarily conserved miR-138-5p binding sites in 3'-UTR region of SIRT1, which was inhibited when overexpression of miR-138-5p. Therefore, it was speculated that elevated expression of SIRT1 may be resulted from inhibition of miR-138-5p after cells exposed to MnCl₂ . Finally, we found that SIRT1 inhibitor EX-527 suppressed Mn-induced autophagy as well as miR-138-5p, while the suppression was reversed by SIRT1-specific activator SRT1720. These results indicated that overexpression of miR-138-5p suppressed Mn-induced autophagy by targeting SIRT1.

Role of sirtuin-1 in diabetic nephropathy

Diabetic nephropathy (DN) is a research priority for scientists around the world because of its high prevalence and poor prognosis. Although several mechanisms have been shown to be involved in its pathogenesis and many useful drugs have been developed, the management of DN remains challenging. Increasing amounts of evidence show that silent information regulator 2 homolog 1 (sirtuin-1), a nicotinamide adenine dinucleotide (NAD+)–dependent protein deacetylase, plays a crucial role in the pathogenesis and development of DN. Clinical data show that gene polymorphisms of sirtuin-1 affect patient vulnerability to DN. In addition, upregulation of sirtuin-1 attenuates DN in various experimental models of diabetes and in renal cells, including podocytes, mesangial cells, and renal proximal tubular cells, incubated with high concentrations of glucose or advanced glycation end products. Mechanistically, sirtuin-1 has its renoprotective effects by modulating metabolic homeostasis and autophagy, resisting apoptosis and oxidative stress, and inhibiting inflammation through deacetylation of histones and the transcription factors p53, forkhead box group O, nuclear factor-κB, hypoxia-inducible factor-1α, and others. Furthermore, some microRNAs have been implicated in the progression of DN because they target sirtuin-1 mRNA. Several synthetic drugs and natural compounds have been identified that upregulate the expression and activity of sirtuin-1, which protects against DN. The present review will summarize advances in knowledge regarding the role of sirtuin-1 in the pathogenesis of DN. The available evidence implies that sirtuin-1 has great potential as a clinical target for the prevention and treatment of diabetes.

Autophagy in Human Health and Disease: Novel Therapeutic Opportunities

SIGNIFICANCE

In eukaryotes, autophagy represents a highly evolutionary conserved process, through which macromolecules and cytoplasmic material are degraded into lysosomes and recycled for biosynthetic or energetic purposes. Dysfunction of the autophagic process has been associated with the onset and development of many human chronic pathologies, such as cardiovascular, metabolic, and neurodegenerative diseases as well as cancer. Recent Advances: Currently, comprehensive research is being carried out to discover new therapeutic agents that are able to modulate the autophagic process in vivo. Recent evidence has shown that a large number of natural bioactive compounds are involved in the regulation of autophagy by modulating several transcriptional factors and signaling pathways.

CRITICAL ISSUES

Critical issues that deserve particular attention are the inadequate understanding of the complex role of autophagy in disease pathogenesis, the limited availability of therapeutic drugs, and the lack of clinical trials. In this context, the effects that natural bioactive compounds exert on autophagic modulation should be clearly highlighted, since they depend on the type and stage of the pathological conditions of diseases.

FUTURE DIRECTIONS

Research efforts should now focus on understanding the survival-supporting and death-promoting roles of autophagy, how natural compounds interact exactly with the autophagic targets so as to induce or inhibit autophagy and on the evaluation of their pharmacological effects in a more in-depth and mechanistic way. In addition, clinical studies on autophagy-inducing natural products are strongly encouraged, also to highlight some fundamental aspects, such as the dose, the duration, and the possible synergistic action of these compounds with conventional therapy.

Chinese Herbal Medicine in Ameliorating Diabetic Kidney Disease via Activating Autophagy

Diabetic kidney disease (DKD), a leading cause of end-stage renal disease (ESRD), has become a serious public health problem worldwide and lacks effective therapies due to its complex pathogenesis. Recent studies suggested defective autophagy involved in the pathogenesis and progression of DKD. Chinese herbal medicine, as an emerging option for the treatment of DKD, could improve diabetic kidney injury by activating autophagy. In this review, we briefly summarize underlying mechanisms of autophagy dysregulation in DKD, including AMP-activated protein kinase (AMPK), the mechanistic target of rapamycin (mTOR), and the sirtuin (Sirt) pathways, and we particularly concentrate on the current status of Chinese herbal medicine treating DKD by regulating autophagy. The advances in our understanding regarding the treatment of DKD via regulating autophagy with Chinese herbal medicine will enhance the clinical application of Chinese medicine as well as discovery of novel therapeutic agents for diabetic patients.

Cell Apoptosis and Autophagy in Renal Fibrosis

Renal fibrosis is the final common pathway of all chronic kidney diseases progressing to end-stage renal diseases. Autophagy, a highly conserved lysosomal degradation pathway, plays important roles in maintaining cellular homeostasis in all major types of kidney cells including renal tubular cells as well as podocytes, mesangial cells and endothelial cells in glomeruli. Autophagy dysfunction is implicated in the pathogenesis of various renal pathologies. Here, we analyze the pathological role and regulation of autophagy in renal fibrosis and related kidney diseases in both glomeruli and tubulointerstitial compartments. Further research is expected to gain significant mechanistic insights and discover pathway-specific and kidney-selective therapies targeting autophagy to prevent renal fibrosis and related kidney diseases.

Is autophagy associated with diabetes mellitus and its complications? A review

Diabetes mellitus (DM) is an endocrine disorder. In coming decades it will be one of the leading causes of death globally. The key factors in the pathogenesis of diabetes are cellular injuries and disorders of energy metabolism leading to severe diabetic complications. Recent studies have confirmed that autophagy plays a pivotal role in diabetes and its complications. It has been observed that autophagy regulates the normal function of pancreatic β cells and insulin-target tissues, such as skeletal muscle, liver, and adipose tissue. This review will summarize the regulation of autophagy in diabetes and its complications, and explore how this process would emerge as a potential therapeutic target for diabetes treatment.

Role of p53/miR-155-5p/sirt1 loop in renal tubular injury of diabetic kidney disease

BACKGROUND

Diabetic kidney disease is a renal microvascular disease caused by diabetes, known as one of the most serious and lethal complications of diabetes. Early renal hypertrophy is the main pathological feature, which gradually leads to the deposition of glomerular extracellular matrix and tubulointerstitial fibrosis, eventually developing irreversible structural damage to the kidneys. Autophagy is a cell self-homeostatic mechanism that is activated under stress conditions and may serve as a protective response to the survival of renal fibrogenic cells. MicroRNA (miRNA) network may be involved in the regulation of fibrosis. The purpose of this study is to assess how miRNAs regulate diabetic kidney disease and autophagy and fibrosis in renal proximal tubular cells under high glucose conditions.

METHODS

Human renal proximal tubular (HK-2) cells were exposed to high glucose in vitro. Bioinformatic analysis was used to select the candidate gene for potential target regulation of miR-155, Sirt1. ATG5, ATG7 is the key to autophagosome formation, regulated by Sirt1. p53 regulates miR-155 expression as a transcription factor. MiR-155 overexpression and inhibition were achieved by transfection of miR-155 mimic and inhibit to evaluate its effect on Sirt1 and autophagy and fibrosis markers. Dual luciferase reporter assays were used to confirm the direct interaction of Sirt1 with miR-155. Overexpression and inhibition of Sirt1 gene were achieved by transfection of Sirt1 plasmid and Sirt1 si to observe its effect on P53. Chip assay experiments confirmed the direct regulation of P53 on miR-155.

RESULTS

Under high glucose conditions, miR-155 was detected in HK-2 cells in concentration gradient, increased expression of p53 and down-regulated expression of sirt1 and autophagy-associated proteins LC3II, ATG5 and ATG7. Dual luciferase reporter assays indicate that miR-155 can target its binding to the Sirt1 3'UTR region to reduce its expression. Under high glucose conditions, over expression of miR-155 decreased the expression of LC3-II and ATG5 in HK-2 cells, while inhibition of miR-155 reversed this effect. Using chip assay testing in HK-2 cells, we demonstrated that p53 binds directly to miR-155.

CONCLUSIONS

The signaling axis of p53, miR-155-5p, and sirt1 in autophagic process might be a critical adapting mechanism for diabetic kidney injury.

Moving to the Rhythm with Clock (Circadian) Genes, Autophagy, mTOR, and SIRT1 in Degenerative Disease and Cancer

BACKGROUND

The mammalian circadian clock and its associated clock genes are increasingly been recognized as critical components for a number of physiological and disease processes that extend beyond hormone release, thermal regulation, and sleep-wake cycles. New evidence suggests that clinical behavior disruptions that involve prolonged shift work and even space travel may negatively impact circadian rhythm and lead to multi-system disease.

METHODS

In light of the significant role circadian rhythm can hold over the body's normal physiology as well as disease processes, we examined and discussed the impact circadian rhythm and clock genes hold over lifespan, neurodegenerative disorders, and tumorigenesis.

RESULTS

In experimental models, lifespan is significantly reduced with the introduction of arrhythmic mutants and leads to an increase in oxidative stress exposure. Interestingly, patients with Alzheimer's disease and Parkinson's disease may suffer disease onset or progression as a result of alterations in the DNA methylation of clock genes as well as prolonged pharmacological treatment for these disorders that may lead to impairment of circadian rhythm function. Tumorigenesis also can occur with the loss of a maintained circadian rhythm and lead to an increased risk for nasopharyngeal carcinoma, breast cancer, and metastatic colorectal cancer. Interestingly, the circadian clock system relies upon the regulation of the critical pathways of autophagy, the mechanistic target of rapamycin (mTOR), AMP activated protein kinase (AMPK), and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1) as well as proliferative mechanisms that involve the wingless pathway of Wnt/β-catenin pathway to foster cell survival during injury and block tumor cell growth.

CONCLUSION

Future targeting of the pathways of autophagy, mTOR, SIRT1, and Wnt that control mammalian circadian rhythm may hold the key for the development of novel and effective therapies against aging- related disorders, neurodegenerative disease, and tumorigenesis.

β-Cell Autophagy in Diabetes Pathogenesis

Nearly 100 years have passed since Frederick Banting and Charles Best first discovered and purified insulin. Their discovery and subsequent improvements revolutionized the treatment of diabetes, and the field continues to move at an ever-faster pace with respect to unique treatments for both type 1 and type 2 diabetes. Despite these advances, we still do not fully understand how apoptosis of the insulin-producing β-cells is triggered, presenting a challenge in the development of preventative measures. In recent years, the process of autophagy has generated substantial interest in this realm due to discoveries highlighting its clear role in the maintenance of cellular homeostasis. As a result, the number of studies focused on islet and β-cell autophagy has increased substantially in recent years. In this review, we will discuss what is currently known regarding the role of β-cell autophagy in type 1 and type 2 diabetes pathogenesis, with an emphasis on new and exciting developments over the past 5 years. Further, we will discuss how these discoveries might be translated into unique treatments in the coming years.

The mechanistic target of rapamycin (mTOR) and the silent mating-type information regulation 2 homolog 1 (SIRT1): oversight for neurodegenerative disorders

As a result of the advancing age of the global population and the progressive increase in lifespan, neurodegenerative disorders continue to increase in incidence throughout the world. New strategies for neurodegenerative disorders involve the novel pathways of the mechanistic target of rapamycin (mTOR) and the silent mating-type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1) that can modulate pathways of apoptosis and autophagy. The pathways of mTOR and SIRT1 are closely integrated. mTOR forms the complexes mTOR Complex 1 and mTOR Complex 2 and can impact multiple neurodegenerative disorders that include Alzheimer's disease, Huntington's disease, and Parkinson's disease. SIRT1 can control stem cell proliferation, block neuronal injury through limiting programmed cell death, drive vascular cell survival, and control clinical disorders that include dementia and retinopathy. It is important to recognize that oversight of programmed cell death by mTOR and SIRT1 requires a fine degree of precision to prevent the progression of neurodegenerative disorders. Additional investigations and insights into these pathways should offer effective and safe treatments for neurodegenerative disorders.

Resveratrol Potently Counteracts Quercetin Starvation-Induced Autophagy and Sensitizes HepG2 Cancer Cells to Apoptosis

SCOPE

Resveratrol (RSV) has been described as a potent antioxidant, antisteatotic, and antitumor compound, and it has also been identified as a potent autophagy inducer. On the other hand, quercetin (QCT) is a dietary flavonoid with known antitumor, anti-inflammatory, and antidiabetic effects. Additionally, QCT increases autophagy. To study the hypothetical synergistic effect of both compounds, we test the combined effect of QCT and RSV on the autophagy process in HepG2 cells.

METHODS AND RESULTS

Autophagy is studied by western blotting, real-time RT-PCR, and cellular staining. Our results clearly indicate a bifunctional molecular effect of RSV. Both polyphenols are individually able to promote autophagy. Strikingly, when RSV is combined with QCT, it promotes a potent reduction of QCT-induced autophagy and influences proapoptotic signaling.

CONCLUSION

RSV acts differentially on the autophagic process depending on the cellular energetic state. We further characterize the molecular mechanisms related to this effect, and we observe that AMP-activated protein kinase (AMPK) phosphorylation, heme oxygenase 1 (HO-1) downregulation, lysosomal membrane permeabilization (LMP), and Zinc (Zn²⁺ ) dynamics could be important modulators of such RSV-related effects and could globally represent a promising strategy to sensitize cancer cells to QCT treatment.

Mesenchymal stem cells pretreated with melatonin ameliorate kidney functions in a rat model of diabetic nephropathy

The aim of this study was to investigate the effect of a regenerative therapy comprising mesenchymal stem cells (MSCs) pretreated with melatonin (MT) as a new therapy for underlying diabetic nephropathy (DN) pathogenesis in a rat model, and its possible effect on autophagy protein Beclin-1. Forty adult male albino Wistar rats were distributed among 4 groups: (i) control, (ii) DN, (iii) MSC-treated, and (iv) treated with MSCs that were pre-incubated in-vitro with MT (5 μmol·L^-1 for 24 h; MSCs + MT). MSCs treatment significantly improved the renal functions and ameliorated the measured underlying DN pathogenesis and elevation of Beclin-1 protein levels compared with the DN group. In-vitro pretreatment of MSCs with MT enhanced proliferation and efficiency, and thus improved the kidney functions by increasing superoxide dismutase (SOD-1) and Beclin-1, and decreasing transforming growth factor (TGF-β) markers in the kidney tissue, compared with the MSC group (P < 0.05). In conclusion: MSCs represent a promising target in DN management, and their effect can be intensified by pretreatment with MT. The elevated levels of Beclin-1 could be a mediator.

Resveratrol protects muscle cells against palmitate-induced cellular senescence and insulin resistance through ameliorating autophagic flux

Skeletal muscle, a highly metabolic tissue, is particularly vulnerable to increased levels of saturated free fatty acids (FFAs). The role of autophagy in saturated FFAs-induced cellular senescence and insulin resistance in skeletal muscle remains unclear. Therefore, the present study was aimed to explore autophagic flux in cellular senescence and insulin resistance induced by palmitate in muscle cells, and whether resveratrol limited these responses. Our results showed that palmitate induced cellular senescence in both myoblasts and myotubes. In addition, palmitate delayed differentiation in myoblasts and inhibited expression of insulin-stimulated p-AKTSer473 in myotubes. The accumulations of autophagosome assessed by tandem fluorescent-tagged LC3 demonstrated that autophagic flux was impaired in both palmitate-treated myoblasts and myotubes. Resveratrol protected muscle cells from palmitate-induced cellular senescence, apoptosis during differentiation, and insulin resistance via ameliorating autophagic flux. The direct influence of autophagic flux on development of cellular senescence and insulin resistance was confirmed by blockage of autophagic flux with chloroquine. In conclusion, impairment of autophagic flux is crucial for palmitate-induced cellular senescence and insulin resistance in muscle cells. Restoring autophagic flux by resveratrol could be a promising approach to prevent cellular senescence and ameliorate insulin resistance in muscle.

Autophagy in diabetic kidney disease: regulation, pathological role and therapeutic potential

Diabetic kidney disease, a leading cause of end-stage renal disease, has become a serious public health problem worldwide and lacks effective therapies. Autophagy is a highly conserved lysosomal degradation pathway that removes protein aggregates and damaged organelles to maintain cellular homeostasis. As important stress-responsive machinery, autophagy is involved in the pathogenesis of various diseases. Emerging evidence has suggested that dysregulated autophagy may contribute to both glomerular and tubulointerstitial pathologies in kidneys under diabetic conditions. This review summarizes the recent findings regarding the role of autophagy in the pathogenesis of diabetic kidney disease and highlights the regulation of autophagy by the nutrient-sensing pathways and intracellular stress signaling in this disease. The advances in our understanding of autophagy in diabetic kidney disease will facilitate the discovery of a new therapeutic target for the prevention and treatment of this life-threatening diabetes complication.

SIRT1 and HIF1α signaling in metabolism and immune responses

SIRT1 and HIF1α are regarded as two key metabolic sensors in cellular metabolism pathways and play vital roles in influencing immune responses. SIRT1 and HIF1α regulate immune responses in metabolism-dependent and -independent ways. Here, we summarized the recent knowledge of SIRT1 and HIF1α signaling in metabolism and immune responses. HIF1α is a direct target of SIRT1. Sometimes, SIRT1 and HIF1α cooperate or act separately to mediate immune responses. In innate immune responses, SIRT1 can regulate the glycolytic activity of myeloid-derived suppressor cells (MDSCs) and influence MDSC functional differentiation. SIRT1 can regulate monocyte function through NF-κB and PGC-1, accompanying an increased NAD⁺ level. The SIRT1-HIF1α axis bridges the innate immune signal to an adaptive immune response by directing cytokine production of dendritic cells in a metabolism-independent manner, promoting the differentiation of CD4⁺ T cells. For adaptive immune cells, SIRT1 can mediate the differentiation of inflammatory T cell subsets in a NAD⁺-dependent manner. HIF1α can stimulate some glycolysis-associated genes and regulate the ATP and ROS generations. In addition, SIRT1-and HIF1α-associated metabolism inhibits the activity of mTOR, thus negatively regulating the differentiation and function of Th9 cells. As immune cells are crucial in controlling immune-associated diseases, SIRT1-and HIF1α associated-metabolism is closely linked to immune-associated diseases, including infection, tumors, allergic airway inflammation, and autoimmune diseases.

Novel Treatment Strategies for the Nervous System: Circadian Clock Genes, Non-coding RNAs, and Forkhead Transcription Factors

BACKGROUND

With the global increase in lifespan expectancy, neurodegenerative disorders continue to affect an ever-increasing number of individuals throughout the world. New treatment strategies for neurodegenerative diseases are desperately required given the lack of current treatment modalities.

METHODS

Here, we examine novel strategies for neurodegenerative disorders that include circadian clock genes, non-coding Ribonucleic Acids (RNAs), and the mammalian forkhead transcription factors of the O class (FoxOs).

RESULTS

Circadian clock genes, non-coding RNAs, and FoxOs offer exciting prospects to potentially limit or remove the significant disability and death associated with neurodegenerative disorders. Each of these pathways has an intimate relationship with the programmed death pathways of autophagy and apoptosis and share a common link to the silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1) and the mechanistic target of rapamycin (mTOR). Circadian clock genes are necessary to modulate autophagy, limit cognitive loss, and prevent neuronal injury. Non-coding RNAs can control neuronal stem cell development and neuronal differentiation and offer protection against vascular disease such as atherosclerosis. FoxOs provide exciting prospects to block neuronal apoptotic death and to activate pathways of autophagy to remove toxic accumulations in neurons that can lead to neurodegenerative disorders.

CONCLUSION

Continued work with circadian clock genes, non-coding RNAs, and FoxOs can offer new prospects and hope for the development of vital strategies for the treatment of neurodegenerative diseases. These innovative investigative avenues have the potential to significantly limit disability and death from these devastating disorders.

Epigenetic Regulatory Mechanisms Induced by Resveratrol

Resveratrol (RVT) is one of the main natural compounds studied worldwide due to its potential therapeutic use in the treatment of many diseases, including cancer, diabetes, cardiovascular diseases, neurodegenerative diseases and metabolic disorders. Nevertheless, the mechanism of action of RVT in all of these conditions is not completely understood, as it can modify not only biochemical pathways but also epigenetic mechanisms. In this paper, we analyze the biological activities exhibited by RVT with a focus on the epigenetic mechanisms, especially those related to DNA methyltransferase (DNMT), histone deacetylase (HDAC) and lysine-specific demethylase-1 (LSD1).

Erythropoietin and mTOR: A "One-Two Punch" for Aging-Related Disorders Accompanied by Enhanced Life Expectancy

Life expectancy continues to increase throughout the world, but is accompanied by a rise in the incidence of non-communicable diseases. As a result, the benefits of an increased lifespan can be limited by aging-related disorders that necessitate new directives for the development of effective and safe treatment modalities. With this objective, the mechanistic target of rapamycin (mTOR), a 289-kDa serine/threonine protein, and its related pathways of mTOR Complex 1 (mTORC1), mTOR Complex 2 (mTORC2), proline rich Akt substrate 40 kDa (PRAS40), AMP activated protein kinase (AMPK), Wnt signaling, and silent mating type information regulation 2 homolog 1 (Saccharomyces cerevisiae) (SIRT1), have generated significant excitement for furthering novel therapies applicable to multiple systems of the body. Yet, the biological and clinical outcome of these pathways can be complex especially with oversight of cell death mechanisms that involve apoptosis and autophagy. Growth factors, and in particular erythropoietin (EPO), are one avenue under consideration to implement control over cell death pathways since EPO can offer potential treatment for multiple disease entities and is intimately dependent upon mTOR signaling. In experimental and clinical studies, EPO appears to have significant efficacy in treating several disorders including those involving the developing brain. However, in mature populations that are affected by aging-related disorders, the direction for the use of EPO to treat clinical disease is less clear that may be dependent upon a number of factors including the understanding of mTOR signaling. Continued focus upon the regulatory elements that control EPO and mTOR signaling could generate critical insights for targeting a broad range of clinical maladies.

Resveratrol-loaded nanoparticles conjugated with kidney injury molecule-1 as a drug delivery system for potential use in chronic kidney disease

AIM

We used resveratrol (Res)-loaded nanoparticles (Res NPs) as a novel method for improving the pharmacokinetic properties of Res and analyzed the effect of Res NPs in chronic kidney disease (CKD).

MATERIALS & METHODS

We coupled anti-kidney injury molecule-1 antibodies to Res NPs and analyzed safety and efficacy.

RESULTS

Res NPs had low toxicity and induced autophagy. Res NPs inhibited the NLRP3 inflammasome and IL-1β secretion. Higher NLRP3 expression levels were observed in peripheral blood monocytic cells of CKD patients than healthy individuals. Treatment with kidney injury molecule-1-Res NPs significantly reduced creatinine and protected against tubulointerstitial injury in a murine model of CKD.

CONCLUSION

Res NPs through NLRP3 inflammasome attenuation and autophagy induction may be as a strategy to prevent CKD.

Metabolic Reprogramming, Autophagy, and Reactive Oxygen Species Are Necessary for Primordial Germ Cell Reprogramming into Pluripotency

Cellular reprogramming is accompanied by a metabolic shift from oxidative phosphorylation (OXPHOS) toward glycolysis. Previous results from our laboratory showed that hypoxia alone is able to reprogram primordial germ cells (PGCs) into pluripotency and that this action is mediated by hypoxia-inducible factor 1 (HIF1). As HIF1 exerts a myriad of actions by upregulating several hundred genes, to ascertain whether the metabolic switch toward glycolysis is solely responsible for reprogramming, PGCs were cultured in the presence of a pyruvate kinase M2 isoform (PKM2) activator, or glycolysis was promoted by manipulating PPARγ. Conversely, OXPHOS was stimulated by inhibiting PDK1 activity in normoxic or in hypoxic conditions. Inhibition or promotion of autophagy and reactive oxygen species (ROS) production was performed to ascertain their role in cell reprogramming. Our results show that a metabolic shift toward glycolysis, autophagy, and mitochondrial inactivation and an early rise in ROS levels are necessary for PGC reprogramming. All of these processes are governed by HIF1/HIF2 balance and strict intermediate Oct4 levels. Histone acetylation plays a role in reprogramming and is observed under all reprogramming conditions. The pluripotent cells thus generated were unable to self-renew, probably due to insufficient Blimp1 downregulation and a lack of Klf4 and cMyc expression.

Reciprocal Crosstalk Between Autophagic and Endocrine Signaling in Metabolic Homeostasis

Autophagy is a cellular quality control and energy-providing process that is under strict control by intra- and extracellular stimuli. Recently, there has been an exponential increase in autophagy research and its implications for mammalian physiology. Autophagy deregulation is now being implicated in many human diseases, and its modulation has shown promising results in several preclinical studies. However, despite the initial discovery of autophagy as a hormone-regulated process by De Duve in the early 1960s, endocrine regulation of autophagy still remains poorly understood. In this review, we provide a critical summary of our present understanding of the basic mechanism of autophagy, its regulation by endocrine hormones, and its contribution to endocrine and metabolic homeostasis under physiological and pathological settings. Understanding the cross-regulation of hormones and autophagy on endocrine cell signaling and function will provide new insight into mammalian physiology as well as promote the development of new therapeutic strategies involving modulation of autophagy in endocrine and metabolic disorders.

Sirtuins in metabolism, DNA repair and cancer

The mammalian sirtuin family has attracted tremendous attention over the past few years as stress adaptors and post-translational modifier. They have involved in diverse cellular processes including DNA repair, energy metabolism, and tumorigenesis. Notably, genomic instability and metabolic reprogramming are two of characteristic hallmarks in cancer. In this review, we summarize current knowledge on the functions of sirtuins mainly regarding DNA repair and energy metabolism, and further discuss the implication of sirtuins in cancer specifically by regulating genome integrity and cancer-related metabolism.

Therapeutic role of sirtuins in neurodegenerative disease and their modulation by polyphenols

Searching for effective therapeutic agents‏‎ to ‎‏prevent‏ ‏neurodegeneration ‎is a challenging task due ‎to ‎the growing list of neurodegenerative disorders associated with a multitude of inter-related pathways.‎ The induction and inhibition of several different signaling pathways has been shown to slow down and/or attenuate ‎neurodegeneration and decline in cognition and locomotor function. Among these signaling pathways, a new class of enzymes known as sirtuins or silent information regulators of gene transcription has been shown to play important regulatory roles in the ageing process. SIRT1, a nuclear sirtuin, has received ‎particular interest due to its role as a deacetylase for several metabolic and signaling proteins involved in stress response, apoptosis, mitochondrial function, self-renewal, and ‎neuroprotection. ‎A new strategy to treat ‎neurodegenerative diseases is targeted therapy. In ‎this ‎paper, we‎ ‎ reviewed up-to-date findings regarding the targeting of ‎SIRT1 by polyphenolic ‎compounds,‎ ‎as a ‎new ‎‏approach in the search for novel, safe and effective treatments for ‎ ‎neurodegenerative ‎diseases. ‎.