Role In Regulation Of Autophagy Research Articles

The PI3K/AKT/mTOR pathway regulates autophagy to induce apoptosis of alveolar epithelial cells in chronic obstructive pulmonary disease caused by PM2.5 particulate matter.

ObjectiveMany lung diseases are associated with changes in autophagic activity. The phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway plays a key regulatory role in autophagy. Our aim was to explore the function of PI3K/AKT/mTOR pathway on autophagy in chronic obstructive pulmonary disease (COPD) caused by particulate matter with a diameter <2.5 µm (PM2.5).MethodsMale C57BL/6 mice were randomly divided into sham, model, and PI3K inhibitor groups. Mice were exposed to PM2.5 for 4 weeks to establish an in vivo COPD model. Alveolar epithelial cells were stimulated with PM2.5 to establish an in vitro COPD model.ResultsIn mice with COPD induced by PM2.5, the PI3K inhibitor PF-04979064 suppressed protein expression of PI3K, p-AKT, and p-mTOR to increase apoptosis of alveolar epithelial cells and reduce autophagy. Short interfering PI3K suppressed the PI3K/AKT/mTOR pathway to induce apoptosis and reduce autophagy of alveolar epithelial cells in an in vitro model of COPD. Activation of PI3K induced the PI3K/AKT/mTOR pathway to reduce apoptosis of alveolar epithelial cells in the in vitro model of COPD by promoting autophagy.ConclusionsThese data demonstrate that PI3K/AKT/mTOR pathway regulates autophagy to induce apoptosis of alveolar epithelial cells in COPD.

Impaired Autophagy Flux is Associated with Proinflammatory Microglia Activation Following Japanese Encephalitis Virus Infection.

Role of autophagy in Japanese encephalitis viral (JEV) infection is not well known. In the present study, we reported the role of autophagy flux in microglia activation, neurobehavioral function and neuronal death using a mouse model of JEV. Markers for autophagy (LC3-II/I, SQSTM1/P62, phos-Akt, phos-AMPK), and neuronal death (cleaved caspase 12, H2Ax, polyubiquitin) were investigated by western blot at 1, 3 and 7days post inoculation. Cathepsin D was measured in cerebral cotex of JEV infected mice spectrophotometrically. Microglia activation and pro-inflammatory cytokines (IL1β, TNF-α, IFNγ, IL6) were measured by immunohistochemistry, western blot and qPCR analysis. In order to determine the neuroinflammatory changes and autophagy mediated neuronal cell death, BV2-microgliaand N2a-neuronal cells were used. Autophagy activation marker LC3-II/I and its substrate SQSTM1/P62 were significantly increased while cathepsin D activity was decreased on day 7 post inoculation in cerebral cortex. Microglia in cortex were activated and showed higher expression of proinflammatory mRNA of IL1β, TNF-α, IFNγ and IL6, with increased DNA damage (H2AX) and neuronal cell death pathways in hippocampus and neurobehavioral dysfunction. Similar observations on JEV infection mediated autophagy flux inhibition and neuronal cell death was found in N2a neuronal cell. Collectively, our study provides evidence on the role of autophagy regulation, microglial activation and neurodegeneration following JEV infection.

Targeting Autophagy Facilitates T Lymphocyte Migration by Inducing the Expression of CXCL10 in Gastric Cancer Cell Lines.

Autophagy is a type of cellular catabolic degradation process that occurs in response to nutrient starvation or metabolic stress, and is a valuable resource for highly proliferating cancer cells. Autophagy also facilitates the resistance of cancer cells to antitumor therapies. However, the involvement of autophagy in regulating CXCL10 expression in gastric cancer (GC) cells and T lymphocyte migration remains unclear. In this study, we aimed to investigate the effect of autophagy inhibition on CXCL10 expression and T lymphocyte infiltration in GC and elucidate the underlying mechanism. Analysis of public databases revealed a positive correlation between CXCL10 expression and both prognosis of patients with GC and the expression profile of T lymphocyte markers in the GCs. Chemotaxis and spheroid infiltration assays revealed that CXCL10 induced T lymphocyte migration and infiltration into GC spheroids, an in vitro three-dimensional cell culture model. In addition, in vitro autophagy inhibition in GC cells increased CXCL10 expression under both normal and hypoxic culture conditions. Further investigation on the underlying mechanism showed that in vitro autophagy inhibition suppressed the JNK signaling pathway and further enhanced CXCL10 expression in GC cells. Collectively, our results provide novel insights for understanding the role of autophagy in regulation of intra-tumor immunity.

Role of autophagy in regulation of cancer cell death/apoptosis during anti-cancer therapy: focus on autophagy flux blockade.

Autophagy is a self-degradation process in which the cytoplasmic cargoes are delivered to the lysosomes for degradation. As the cargoes are degraded/recycled, the autophagy process maintains the cellular homeostasis. Anti-cancer therapies induce apoptosis and autophagy concomitantly, and the induced autophagy normally prevents stress responses that are being induced. In such cases, the inhibition of autophagy can be a reasonable strategy to enhance the efficacy of anti-cancer therapies. However, recent studies have shown that autophagy induced by anti-cancer drugs causes cell death/apoptosis induction, indicating a controversial role of autophagy in cancer cell survival or death/apoptosis. Therefore, in the present review, we aimed to assess the signaling mechanisms involved in autophagy and cell death/apoptosis induction during anti-cancer therapies. This review summarizes the process of autophagy, autophagy flux and its blockade, and measurement and interpretation of autophagy flux. Further, it describes the signaling pathways involved in the blockade of autophagy flux and the role of signaling molecules accumulated by autophagy blockade in cell death/apoptosis in various cancer cells during anti-cancer therapies. Altogether, it implies that factors such as types of cancer, drug therapies, and characteristics of autophagy should be evaluated before targeting autophagy for cancer treatment.

Dual Role of Autophagy in Regulation of Mesenchymal Stem Cell Senescence.

During their development and overall life, mesenchymal stem cells (MSCs) encounter a plethora of internal and external stress signals and therefore, they need to put in action homeostatic changes in order to face these stresses. To this aim, similar to other mammalian cells, MSCs are endowed with two crucial biological responses, autophagy and senescence. Sharing of a number of stimuli like shrinkage of telomeres, oncogenic and oxidative stress, and DNA damage, suggest an intriguingly close relationship between autophagy and senescence. Autophagy is at first reported to suppress MSC senescence by clearing injured cytoplasmic organelles and impaired macromolecules, yet recent investigations also showed that autophagy can promote MSC senescence by inducing the production of senescence-associated secretory proteins (SASP). These apparently contrary contributions of autophagy may mirror an intricate image of autophagic regulation on MSC senescence. We here tackle the pro-senescence and anti-senescence roles of autophagy in MSCs while concentrating on some possible mechanistic explanations of such an intricate liaison. Clarifying the autophagy/senescence relationship in MSCs will help the development of more effective and safer therapeutic strategies.

LncRNAs as Therapeutic Targets for Autophagy-involved Cardiovascular Diseases: A Review of Molecular Mechanism and T herapy Strategy.

Cardiovascular diseases (CVDs) remain the leading cause of death worldwide. The concept of precision medicine in CVD therapy today requires the incorporation of individual genetic and environmental variability to achieve personalized disease prevention and tailored treatment. Autophagy, an evolutionarily conserved intracellular degradation process, has been demonstrated to be essential in the pathogenesis of various CVDs. Nonetheless, there have been no effective treatments for autophagy- involved CVDs. Long noncoding RNAs (lncRNAs) are noncoding RNA sequences that play versatile roles in autophagy regulation, but much needs to be explored about the relationship between lncRNAs and autophagy-involved CVDs. Increasing evidence has shown that lncRNAs contribute considerably to modulate autophagy in the context of CVDs. In this review, we first summarize the current knowledge of the role lncRNAs play in cardiovascular autophagy and autophagy-involved CVDs. Then, recent developments of antisense oligonucleotides (ASOs) designed to target lncRNAs to specifically modulate autophagy in diseased hearts and vessels are discussed, focusing primarily on structure-activity relationships of distinct chemical modifications and relevant clinical trials. ASOs are promising in cardiovascular drug innovation. We hope that future studies of lncRNA-based therapies would overcome existing technical limitations and help people who suffer from autophagy-involved CVDs.

Redox signaling in the pathogenesis of human disease and the regulatory role of autophagy.

Aberrant cell death signaling and oxidative stress are implicated in myriad of human pathological states such as neurodegenerative, cardiovascular, metabolic and liver diseases, as well as drug-induced toxicities. While regulated cell death and mild oxidative stress are essential during normal tissue homeostasis, deregulated signaling can trigger massive depletion in a particular cell type and/or damage tissues and impair organ function with deleterious consequences that manifest as disease states. If regeneration cannot restore tissue homeostasis, the severity of the disease correlates with the extent of cell loss. Cell death can be executed via multiple modalities such as apoptosis, necrosis, pyroptosis, necroptosis and ferroptosis, depending on cell autonomous mechanisms (e.g., reactive oxygen species production, calcium overload and altered proteostasis) and/or non-cell autonomous processes (e.g., environmental stress, irradiation, chemotherapeutic agents, inflammation and pathogens). Accordingly, the inhibition of aberrant cell death and oxidative stress together with activation of autophagy, a regulated self-degradation process, are progressively emerging as relevant cytoprotective strategies to sustain homeostasis. In this review, we summarize the current literature on the crosstalk between cellular redox state and cell fate signaling, specifically from the standpoint of autophagy and its role in the maintenance of tissue/organ homeostasis via regulating oxidative stress and the potential implications for the design of novel therapeutic strategies.

Autophagy and Age-Related Eye Diseases.

Background Autophagy is a catabolic process that depends on the lysosome. It is usually used to maintain cellular homeostasis, survival and development by degrading abnormal substances and dysfunctional organelles, especially when the cell is exposed to starvation or other stresses. Increasing studies have reported that autophagy is associated with various eye diseases, of which aging is one of the important factors. Objective To summarize the functional and regulatory role of autophagy in ocular diseases with aging, and discuss the possibility of autophagy-targeted therapy in age-related diseases. Methods PubMed searches were performed to identify relevant articles published mostly in the last 5 years. The key words were used to retrieve including “autophagy”, “aging”, “oxidative stress AND autophagy”, “dry eye AND autophagy”, “corneal disease AND autophagy”, “glaucoma AND autophagy”, “cataract AND autophagy”, “AMD AND autophagy”, “cardiovascular diseases AND autophagy”, “diabetes AND autophagy”. After being classified and assessed, the most relevant full texts in English were chosen. Results Apart from review articles, more than two research articles for each age-related eye diseases related to autophagy were retrieved. We only included the most relevant and recent studies for summary and discussion. Conclusion Autophagy has both protective and detrimental effects on the progress of age-related eye diseases. Different types of studies based on certain situations in vitro showed distinct results, which do not necessarily coincide with the actual situation in human bodies completely. It means the exact role and regulatory function of autophagy in ocular diseases remains largely unknown. Although autophagy as a potential therapeutic target has been proposed, many problems still need to be solved before it applies to clinical practice.

MicroRNAs play an essential role in autophagy regulation in various disease phenotypes.

Autophagy is a highly conserved catabolic process and fundamental biological process in eukaryotic cells. It recycles intracellular components to provide nutrients during starvation and maintains quality control of organelles and proteins. In addition, autophagy is a well‐organized homeostatic cellular process that is responsible for the removal of damaged organelles and intracellular pathogens. Moreover, it also modulates the innate and adaptive immune systems. Micro ribonucleic acids (microRNAs) are a mature class of post‐transcriptional modulators that are widely expressed in tissues and organs. And, it can suppress gene expression by targeting messenger RNAs for translational repression or, at a lesser extent, degradation. Research indicates that microRNAs regulate autophagy through different pathways, playing an essential role in the treatment of various diseases. It is an important regulator of fundamental cellular processes such as proliferation, autophagy, and cell apoptosis. In this review article, we first review the current knowledge of autophagy and the function of microRNAs. Then, we summarize the mechanism of autophagy and the signaling pathways related to autophagy by citing at least the main proteins involved in the different phases of the process. Second, we introduce other members of RNA and report some examples in various pathologies. Finally, we review the current literature regarding microRNA‐based therapies for cancer, atherosclerosis, cardiac disease, tuberculosis, and viral diseases. MicroRNAs can cause autophagy upregulation or downregulation by targeting genes or affecting autophagy‐related signaling pathways. Therefore, the microRNAs have a huge potential in autophagy regulation, and it is the function as diagnostic and prognostic markers.

Abstract 273: The Role of Estrogen in Protection of Skeletal Muscle Function in Diastolic Dysfunction

Diastolic dysfunction (DD) is prevalent in elderly post-menopausal women. In addition to impaired cardiac relaxation and output, DD is associated with loss of skeletal muscle mass, muscle strength and function, and exercise capacity. Understanding the mechanisms of estrogen (E2)-mediated regulation of skeletal muscle structure and function in DD can have broader implications in understanding the progression of heart disease in post-menopausal women. In muscle, E2 regulates autophagy and mitophagy, processes that orchestrate degradation and recycling of damaged cellular components to maintain healthy tissue and conserve energy. However, this role of E2 under a physiological stress such as DD, is largely unknown. Our study aimed to understand the relationship between E2, autophagy/mitophagy and muscle function in DD. We hypothesized that estrogen receptor (ER) signaling plays a direct role in regulation of autophagy and mitophagy-mediated maintenance of muscle mass and muscle mitochondrial function in DD. Sham or ovariectomy (OVX) surgeries were performed to induce E2-deficiency, followed by induction of DD by administering hypertension agents L-NAME and angiotensin II. NMR analysis revealed significantly reduced total lean mass in OVX mice with DD, further confirmed by direct measurement of gastrocnemius muscle mass. Expression of ERα target-genes PDK4 and STAT3 were reduced in muscle of OVX mice with DD. DD significantly reduced LC3B II/I ratio in muscle, indicative of reduced autophagy. Consistent with this, expression of transcription factor FoxO3, a master-regulator of multiple autophagy and mitophagy genes, was reduced in OVX mice with DD compared to sham control mice. Expression of SDHA gene coding for mitochondrial respiratory chain subunit II, was reduced in sham and OVX mice with DD compared to sham control mice. Mitochondrial respiratory function measured from isolated muscle mitochondria, was reduced in sham and OVX mice with DD compared to sham control mice, and in OVX mice with DD compared to OVX control mice, indicating compromised skeletal muscle mitochondrial function. Our findings indicate that OVX-induced E2-deficiency and DD leads to muscle impairments, including defects in mitochondrial function.

HPV Infection Downregulates the Expression of Autophagy-Related Genes in Condylomata Acuminata

Background: Condylomata acuminata are benign anogenital warts caused by human papillomavirus (HPV) infection with a high recurrence rate. Autophagy plays an important role in maintaining internal environmental stability. However, the role of autophagy regulation in the anogenital warts caused by HPV infection remains unknown. Objective: A multigroup case-control study was designed to identify the autophagy gene fingerprint involved in anogenital warts arising from infections with different HPV genotypes. Methods: Human autophagy PCR arrays were performed on the initial 18 participants grouped by their different HPV genotypes for gene expression-profiling analysis. The negative control was skin samples collected during plastic surgery on the chest from a group of individuals who showed none of the clinical symptoms or evidence of HPV infection. Real-time polymerase chain reaction (qPCR) was performed to validate the microarray results in another 24 individuals. Results: Out of 84 genes involved in autophagy, different autophagic responses were found among the 29 genes that encode autophagy machinery components, and expression levels of 13 of these genes were downregulated. Finally, we verified that the expression levels of 2 key genes that participate in the formation of autophagosomes, ATG3 and ­BECLIN1, were downregulated in the HPV infection groups independently of genotype compared with the control group. Conclusions: These findings showed that HPV infection downregulated the expression of ATGs in CA. Additionally, there were no differences in the expression of ATGs between the different HPV genotype infection groups. This study provided new insights into the autophagic response to HPV infection.

Sodium (±)-5-bromo-2-(α-hydroxypentyl) benzoate ameliorates pressure overload-induced cardiac hypertrophy and dysfunction through inhibiting autophagy.

Sodium (±)‐5‐bromo‐2‐(a‐hydroxypentyl) benzoate (generic name: brozopine, BZP) has been reported to protect against stroke‐induced brain injury and was approved for Phase II clinical trials for treatment of stroke‐related brain damage by the China Food and Drug Administration (CFDA). However, the role of BZP in cardiac diseases, especially in pressure overload‐induced cardiac hypertrophy and heart failure, remains to be investigated. In the present study, angiotensin II stimulation and transverse aortic constriction were employed to induce cardiomyocyte hypertrophy in vitro and in vivo, respectively, prior to the assessment of myocardial cell autophagy. We observed that BZP administration ameliorated cardiomyocyte hypertrophy and excessive autophagic activity. Further results indicated that AMP‐activated protein kinase (AMPK)‐mediated activation of the mammalian target of rapamycin (mTOR) pathway likely played a role in regulation of autophagy by BZP after Ang II stimulation. The activation of AMPK with metformin reversed the BZP‐induced suppression of autophagy. Finally, for the first time, we demonstrated that BZP could protect the heart from pressure overload‐induced hypertrophy and dysfunction, and this effect is associated with its inhibition of maladaptive cardiomyocyte autophagy through the AMPK‐mTOR signalling pathway. These findings indicated that BZP may serve as a promising compound for treatment of pressure overload‐induced cardiac remodelling and heart failure.

Alpha-lipoic acid alleviated 6-OHDA-induced cell damage by inhibiting AMPK/mTOR mediated autophagy

Oxidative stress and autophagy are involved in the pathogenesis of Parkinson's disease. The relationship between oxidative stress and autophagy is a hot spot of scientific research. Alpha-lipoic acid (ALA) is a natural antioxidant. ALA has been reported to reduce oxidative stress and apoptosis in PD models, but its role in autophagy regulation of PD has been reported very little. In this study, we investigated the protective effects of ALA on 6-OHDA induced neurotoxicity, and explored the potential mechanisms associated with the crosstalk between oxidative stress and autophagy. Our results showed that 6-OHDA induced accumulation of ROS in SH-SY5Y cells, accompanied by excessive autophagy and apoptosis. ALA protected against 6-OHDA induced neuronal death through inhibition of oxidative stress and autophagy. Furthermore, we found that ALA inhibited AMPK phosphorylation while activated mTOR phosphorylation thereby blocking AMPK/mTOR signaling pathway involved autophagy. In conclusion, ALA alleviated 6-OHDA induced cell injury possibly by inhibiting autophagy mediated by AMPK/mTOR pathway.

Epigenetic Regulation of Autophagy.

Epigenetics refers to reversible and hereditary changes in gene expression without alterations in DNA sequences, such as DNA methylation, histone modification and chromatin remodelling. It was first proposed by Waddington in the book Introduction to Modern Genetics in 1939. Autophagy includes at least four processes: autophagy induction, autophagosome formation, autophagosome fusion with lysosomes and lysosomal degradation of cytoplasmic components. The whole process is complex and dynamic, and involves at least 30 autophagy-related proteins. This degradative machinery is regulated by multiple signal molecules. Autophagy was once considered to be a cytoplasmic event; however, in recent years, emerging evidence suggests that nuclear components (transcription factors, histone modification, microRNAs, etc.) also play an important role in autophagy regulation (Baek and Kim 2017). Among them, epigenetic regulation of autophagy has gained much attention. The epigenetic machinery can not only modify autophagy-related genes but also affect some signal molecule genes that regulate autophagy, thus impacting their transcription and subsequent autophagy. This chapter focuses on the role and recent progress in autophagy regulation by DNA methylation and histone modifications. The role of non-coding RNAs such as microRNA in autophagy regulation will be covered in other chapters.

New Insights on Intermediary Metabolism for a Better Understanding of Nutrition in Teleosts.

The rapid development of aquaculture production throughout the world over the past few decades has led to the emergence of new scientific challenges to improve fish nutrition. The diet formulations used for farmed fish have been largely modified in the past few years. However, bottlenecks still exist in being able to suppress totally marine resources (fish meal and fish oil) in diets without negatively affecting growth performance and flesh quality. A better understanding of fish metabolism and its regulation by nutrients is thus mandatory. In this review, we discuss four fields of research that are highly important for improving fish nutrition in the future: ( a) fish genome complexity and subsequent consequences for metabolism, ( b) microRNAs (miRNAs) as new actors in regulation of fish metabolism, ( c) the role of autophagy in regulation of fish metabolism, and ( d) the nutritional programming of metabolism linked to the early life of fish.

TRIM59 regulates autophagy through modulating both the transcription and the ubiquitination of BECN1

ABSTRACTMacroautophagy/autophagy is a multistep cellular process that sequesters cytoplasmic components for lysosomal degradation. BECN1/Beclin1 is a central protein that assembles cofactors for the formation of a BECN1-PIK3C3-PIK3R4 complex to trigger the autophagy protein cascade. Discovering the regulators of BECN1 is important for understanding the mechanism of autophagy induction. Here, we demonstrate that TRIM59, a tripartite motif protein, plays an important role in autophagy regulation in non-small cell lung cancer (NSCLC). On the one hand, TRIM59 regulates the transcription of BECN1 through negatively modulating the NFKB pathway. On the other hand, TRIM59 regulates TRAF6 induced K63-linked ubiquitination of BECN1, thus affecting the formation of the BECN1-PIK3C3 complex. We further demonstrate that TRIM59 can mediate K48-linked ubiquitination of TRAF6 and promote the proteasomal degradation of TRAF6. Taken together, our findings reveal novel dual roles for TRIM59 in autophagy regulation by affecting both the transcription and the ubiquitination of BECN1.Abbreviations: ACTB: actin beta; BECN1: beclin 1; CHX: cycloheximide; CQ: chloroquine; GFP: green fluorescent protein; HA: haemagglutinin tag; His: polyhistidine tag; LC3B: microtubule associated protein 1 light chain 3 beta; NFKB: nuclear factor kappa B; NFKBIA: NFKB inhibitor alpha; NSCLC: non-small cell lung cancer; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; RELA: RELA proto-oncogene, NF-kB subunit; SQSTM1: sequestosome 1; tGFP: Turbo green fluorescent protein; TRAF6: TNF receptor associated factor 6; TRIM59: tripartite motif containing 59; B: ubiquitin

NNMT depletion contributes to liver cancer cell survival by enhancing autophagy under nutrient starvation

Nicotinamide N-methyl transferase (NNMT) transfers a methyl group from S-adenosyl-L-methionine (SAM) to nicotinamide (NAM), producing 1-methylnicotinamide (1MNA). NNMT has been implicated in several cancer types and recently in metabolism, but its role in autophagy regulation has not yet been investigated. In this study, we determined that NNMT negatively regulated autophagy at the stage of ULK1 activation through protein phosphatase 2A (PP2A) activity. Specifically, NNMT knockdown increased PP2A methylation and subsequently enhanced phosphatase activity. Consequent p-ULK1 (S638) dephosphorylation derepressed ULK1 activity, resulting in autophagy induction. Accordingly, NNMT downregulation rescued tumor cells under nutrient deficiency in vivo, which was alleviated by ULK1 inhibitor treatment. In summary, our results suggest a novel mechanism by which tumor cells protect themselves against nutrient deprivation through NNMT suppression to accelerate autophagy.

TGF-β3 Promotes MUC5AC Hyper-Expression by Modulating Autophagy Pathway in Airway Epithelium

Mucus secretion accumulation in the airways may act as a contributing factor for the development of airflow limitation in severe fetal asthma patients. Accumulated evidences showed that transforming growth factor beta (TGF-β) plays a regulatory role in airway remodeling including mucus hyper-secretion in asthma. However, the detailed molecular mechanisms of TGF-β3 induced MUC5AC hyper-expression in airway epithelium remains unclear. Here, we demonstrated the pivotal roles of autophagy in regulation of MUC5AC hyper-production induced by TGF-β3 in airway epithelium. Our experimental data showed that inhibiting autophagy pathway in repeated ovalbumin (OVA) exposed mice exhibited decreased airway hyper-response and airway inflammation, diminishing the expression of Muc5ac and TGF-β3. Furthermore, our studies demonstrated that autophagy was induced upon exposure to TGF-β3 and then mediated MUC5AC hyper-expression by activating the activator protein-1 (AP-1) in human bronchial epithelial cells. Finally, Smad2/3 pathway was involved in TGF-β3-induced MUC5AC hyper-expressions by promoting autophagy. These data indicated that autophagy was required for TGF-β3 induced airway mucous hyper-production, and that inhibition of autophagy exerted therapeutic benefits for TGF-β3 induced airway mucus secretion.

Regulation of Hepatic Insulin Sensitivity and Hepatic Steatosis by ULK1

Hepatic insulin resistance (IR) plays a central role in the pathophysiology of impaired glucose tolerance, type 2 diabetes and nonalcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH), which is emerging as a major cause of liver failure and hepatocellular carcinoma. Impaired autophagy may also contribute to hepatic insulin resistance, but the interactions between insulin sensitivity and autophagy are incompletely understood. The Unc-51 Like Autophagy Activating Kinase 1 (ULK1) is an early stage autophagosome formation related kinase that is activated in selective autophagy and may be independent of nutrient or energy status. We observed that in addition to its role in autophagy regulation, ULK1 may also directly regulate insulin signaling by modulating AKT dephosphorylation. Specifically, silencing ULK1 significantly impairs insulin-stimulated activation of AKT and GSK3β in hepatocytes in the absence of significant changes in autophagy. To understand the role of ULK1 in hepatic insulin action ULK1 liver specific knock-out mice were generated. Body weight increased in L-ULK1KO relative to wild type mice on normal chow diet or 60% high fat diet. L-ULK1 KO mice exhibited impaired glucose tolerance and insulin resistance. Serum concentrations of insulin, triglyceride, cholesterol, AST and ALT were increased. Phosphorylation levels of FOXO1 and FOXO3a were decreased in concert with increased expression levels of PEPCK and G6pase and increased hepatic glucose production. In contrast, L-ULK2 KO mice were phenotypically normal. Thus, ULK1 independently and directly regulates hepatic insulin sensitivity and glucose homeostasis. Disclosure Y. Koo: None. M.P. Garneau: None. Q. Zhang: None. E. Abel: None.

Regulatory role of autophagy in development of pulmonary artery hypertension

Pulmonary arterial hypertension (PAH) is a multi-etiological chronic disease characterized by a progressive elevation in pulmonary resistance and vascular remodeling. Its pathogenesis is complicated. Recently, emerging researches suggest that autophagy, as a self-protection mechanism maintaining the intracellular environment homeostasis in eukaryotes, participate in the occurrence and development of various types of PAH. Autophagy can regulate the survival, apoptosis of pulmonary vascular wall cells and secretion of vasoactive substances and inflammatory cytokines, thus influencing pulmonary vascular homeostasis. Some drugs based on regulating autophagy activity can effectively improve the prognosis of PAH. In this article, the regulatory role of autophagy on the development of pulmonary hypertension is reviewed to provide insight into PAH and its treatment.