AMP-activated Protein Kinase Activation Research Articles

AMPK deficiency inhibits fatty acid oxidation in endothelial progenitor cells to aggravate impaired angiogenesis after ischemic stroke in hyperlipidemic mice

ABSTRACT Background Hyperlipidemia is a risk factor for stroke, and worsens neurological outcome after stroke. Endothelial progenitor cells (EPCs), which become dysfunctional in cerebral ischemia, hold capacity to promote revascularization. Objective We investigated the role of dyslipidemia in impairment of EPC-mediated angiogenesis in cerebral ischemic mice. Methods and Results The high fat diet (HFD)-fed mice following by ischemic stroke exhibited increased infarct volumes and neurological severity scores, and poorer angiogenesis. Bone marrow-EPCs treated with palmitic acid (PA) showed impaired functions and inhibited activity of AMP-activated protein kinase (AMPK). Notably, AMPK deficiency aggravated EPC dysfunction, further decreased mitochondrial membrane potential, and increased reactive oxygen species level in EPCs with PA treatment. Furthermore, the expression of fatty acid oxidation (FAO)-related genes was remarkably reduced, and carnitine palmitoyltransferase 1A (CPT1A) protein expression was downregulated in AMPK-deficient EPCs. AMPK deficiency aggravated neurological severity scores and angiogenesis in ischemic brain of HFD-fed mice, accompanied by suppressed protein level of CPT1A. EPC transplantation corrected impaired neurological severity scores and angiogenesis in AMPK-deficient mice. Conclusion Our findings suggest that AMPK deficiency aggravates poor angiogenesis in ischemic brain by mediating FAO and oxidative stress thereby inducing EPC dysfunction in hyperlipidemic mice.

GDF15 ameliorates sepsis-induced lung injury via AMPK-mediated inhibition of glycolysis in alveolar macrophage

Growth differentiation factor 15 (GDF15) as a stress response cytokine is involved in the development and progression of several diseases associated with metabolic disorders. However, the regulatory role and the underlying mechanisms of GDF15 in sepsis remain poorly defined. Our study analyzed the levels of GDF15 and its correlations with the clinical prognosis of patients with sepsis. In vivo and in vitro models of sepsis were applied to elucidate the role and mechanisms of GDF15 in sepsis-associated lung injury. We observed strong correlations of plasma GDF15 levels with the levels of C-reactive protein (CRP), procalcitonin (PCT), lactate dehydrogenase (LDH), and lactate as well as Sequential Organ Failure Assessment (SOFA) scores in patients with sepsis. In the mouse model of lipopolysaccharide-induced sepsis, recombinant GDF15 inhibited the proinflammatory responses and alleviated lung tissue injury. In addition, GDF15 decreased the levels of cytokines produced by alveolar macrophages (AMs). The anti-inflammatory effect of glycolysis inhibitor 2-DG on AMs during sepsis was mediated by GDF15 via inducing the phosphorylation of the α-subunit of eukaryotic initiation factor 2 (eIF2α) and the expression of activating transcription factor 4 (ATF4). Furthermore, we explored the mechanism underlying the beneficial effects of GDF15 and found that GDF15 inhibited glycolysis and mitogen-activated protein kinases (MAPK)/nuclear factor-κB (NF-κB) signaling via promoting AMPK phosphorylation. This study demonstrated that GDF15 inhibited glycolysis and NF-κB/MAPKs signaling via activating AMP-activated protein kinase (AMPK), thereby alleviating the inflammatory responses of AMs and sepsis-associated lung injury. Our findings provided new insights into novel therapeutic strategies for treating sepsis.

Crithmum maritimum Extract Restores Lipid Homeostasis and Metabolic Profile of Liver Cancer Cells to a Normal Phenotype.

Hepatocellular carcinoma (HCC) is an alarming epidemiological clinical problem worldwide. Pharmacological approaches currently available do not provide adequate responses due to poor effectiveness, high toxicity, and serious side effects. Our previous studies have shown that the wild edible plant Crithmum maritimum L. inhibits the growth of liver cancer cells and promotes liver cell differentiation by reducing lactic acid fermentation (Warburg effect). Here, we aimed to further characterise the effects of C. maritimum on lipid metabolism and markers of cellular metabolic health, such as AMP-activated protein kinase (AMPK), Sirtuin 1 (SIRT1), and Sirtuin 3 (SIRT3), as well as the insulin signalling pathway. To better mimic the biological spectrum of HCC, we employed four HCC cell lines with different degrees of tumorigenicity and lactic acid fermentation/Warburg phenotype. Lipid accumulation was assessed by Oil Red O (ORO) staining, while gene expression was measured by real-time quantitative PCR (RT-qPCR). The activation of AMPK and insulin signalling pathways was determined by Western blotting. Results indicate that C. maritimum prevents lipid accumulation, downregulates lipid and cholesterol biosynthesis, and modulates markers of metabolic health, such as AMPK, SIRT1 and SIRT3. This modulation is different amongst HCC cell lines, revealing an important functional versatility of C. maritimum. Taken together, our findings corroborate the importance of C. maritimum as a valuable nutraceutical, reinforcing its role for the improvement of metabolic health.

AMPK and glucose deprivation exert an isoform-specific effect on the expression of Na+,K+-ATPase subunits in cultured myotubes.

In skeletal muscle, Na+,K+-ATPase (NKA), a heterodimeric (α/β) P-type ATPase, has an essential role in maintenance of Na+ and K+ homeostasis, excitability, and contractility. AMP-activated protein kinase (AMPK), an energy sensor, increases the membrane abundance and activity of NKA in L6 myotubes, but its potential role in regulation of NKA content in skeletal muscle, which determines maximum capacity for Na+ and K+ transport, has not been clearly delineated. We examined whether energy stress and/or AMPK affect expression of NKA subunits in rat L6 and primary human myotubes. Energy stress, induced by glucose deprivation, increased protein content of NKAα1 and NKAα2 in L6 myotubes, while decreasing the content of NKAα1 in human myotubes. Pharmacological AMPK activators (AICAR, A-769662, and diflunisal) modulated expression of NKA subunits, but their effects only partially mimicked those that occurred in response to glucose deprivation, indicating that AMPK does not mediate all effects of energy stress on NKA expression. Gene silencing of AMPKα1/α2 increased protein levels of NKAα1 in L6 myotubes and NKAα1 mRNA levels in human myotubes, while decreasing NKAα2 protein levels in L6 myotubes. Collectively, our results suggest a role for energy stress and AMPK in modulation of NKA expression in skeletal muscle. However, their modulatory effects were not conserved between L6 myotubes and primary human myotubes, which suggests that coupling between energy stress, AMPK, and regulation of NKA expression in vitro depends on skeletal muscle cell model.

3-Epi-betulinic acid 3-O-β-D-glucopyranoside (eBAG) induces autophagy by activation of AMP-activated protein kinase in hepatocellular carcinoma

3-Epi-betulinic acid 3-O-β-D-glucopyranoside (eBAG) is a pentacyclic triterpene mainly distributed in food and medicinal plants, which exhibits various pharmacological properties. However, whether these functions are attributed to eBAG or additional components in these plants remain unknown. Herein, we report that eBAG exerted an inhibitory activity against hepatocellular carcinoma and esophageal cancer cells. EBAG induced non-apoptotic cell death in hepatocellular carcinoma cells. The eBAG-induced cell death was inhibited by knock-down of autophagy related gene (ATG) 5 and ATG7, by administration of 3-methyladenine, a selective autophagy inhibitor that suppresses phosphoinositide 3-kinase (PI3K), and by chloroquine, a classic autophagy flux inhibitor. We demonstrated that eBAG induced an autophagy-mediated cell death. Application of eBAG mimicked cellular bioenergetics depletion leading to the reduction of intracellular ATP, activation of AMP-activated protein kinase (AMPK), and inhibition of mTOR. Co-treatment with compound C, an AMPK inhibitor, abrogated cell death induced by eBAG. We further validated the anti-tumor effect of eBAG in the murine xenograft model of hepatocellular carcinoma and found that eBAG treatment promoted the induction of autophagy and reduction of tumor growth in mice. As a functional food ingredient, eBAG is a potential therapeutic agent for the treatment of hepatocellular carcinoma and esophageal cancer.

Differential Expression Profiles and Bioinformatics Analysis of tRNA-derived Small RNAs in Epicardial fat of Patients with Atrial Fibrillation

The exact processes underlying atrial fibrillation (AF) are still unclear. It has been suggested that epicardial adipose tissue (EAT) may contribute to arrhythmias and can release various bioactive molecules, including exosomes containing tRNA-derived small RNAs (tsRNAs). Numerous studies have indicated that these tsRNAs can significantly affect key cellular functions. However, there is currently no research investigating the relationship between tsRNAs from EAT and AF. In order to explore the regulatory mechanisms of tsRNAs from EAT associated with AF, we conducted RNA-sequencing analysis on EAT samples collected from 6 AF patients and 6 control subjects with sinus rhythm. Our analysis revealed an upregulation of 146 tsRNAs and a downregulation of 126 tsRNAs in AF. Furthermore, we randomly selected four tsRNAs (tRF-SeC-TCA-001, tiRNA-Gly-CCC-003, tRF-Gly-GCC-002, and tRF-Tyr-GTA-007) for validation using quantitative reverse transcription-polymerase chain reaction. Following this, bioinformatic analyses revealed that the target genes of these tsRNAs were prominently involved in the regulation of cell adhesion and various cellular processes mediated by plasma membrane adhesion molecules. Additionally, based on KEGG analysis, it was suggested that the majority of these target genes might contribute to the pathogenesis of AF through processes such as glycosaminoglycan biosynthesis, AMP-activated protein kinase activity, and the insulin signaling pathway. Our results elucidate changes in the expression profiles of tsRNAs within EAT samples obtained from AF patients, and they forecast potential target genes and interactions between tsRNAs and mRNA within EAT that could contribute to the pathogenesis of AF.

Solanum nigrum L. berries extract ameliorated the alcoholic liver injury by regulating gut microbiota, lipid metabolism, inflammation, and oxidative stress

Solanum nigrum L. (SN) berry is an edible berry containing abundant polyphenols and bioactive compounds, which possess antioxidant and antiinflammatory properties. However, the effects of SN on alcohol-induced biochemical changes in the enterohepatic axis remain unclear. In the current study, a chronic ethanol-fed mice ALD model was used to test the protective mechanisms of SN berries. Microbiota composition was determined via 16S rRNA sequencing, we found that SN berries extract (SNE) improved intestinal imbalance by reducing the Firmicutes to Bacteroides ratio, restoring the abundance of Akkermansia microbiota, and reducing the abundance of Allobaculum and Shigella. SNE restored the intestinal short-chain fatty acids content. In addition, liver transcriptome data analysis revealed that SNE primarily affected the genes involved in lipid metabolism and inflammatory responses. Furthermore, SNE ameliorated hepatic steatosis in alcohol-fed mice by activating AMP-activated protein kinase (AMPK), acetyl-CoA carboxylase (ACC), peroxisome proliferator-activated receptor α (PPAR-α). SNE reduced the expression of toll-like receptor 4 (TLR4), myeloid differentiation factor-88 (MyD88) nuclear factor kappa-B (NF-κB), which can indicate that SNE mainly adjusted LPS/TLR4/MyD88/NF-κB pathway to reduce liver inflammation. SNE enhanced hepatic antioxidant capacity by regulating NRF2-related protein expression. SNE alleviates alcoholic liver injury by regulating of gut microbiota, lipid metabolism, inflammation, and oxidative stress. This study may provide a reference for the development and utilization of SN resources.

Anti-Obesity and Anti-Diabetic Effects of Ostericum koreanum (Ganghwal) Extract.

"Ganghwal" is a widely used herbal medicine in Republic of Korea, but it has not been reported as a treatment strategy for obesity and diabetes within adipocytes. In this study, we determined that Ostericum koreanum extract (OKE) exerts an anti-obesity effect by inhibiting adipogenesis and an anti-diabetic effect by increasing the expression of genes related to glucose uptake in adipocytes and inhibiting α-glucosidase activity. 3T3-L1 preadipocytes were differentiated for 8 days in methylisobutylxanthine, dexamethasone, and insulin medium, and the effect of OKE was confirmed by the addition of 50 and 100 µg/mL of OKE during the differentiation process. This resulted in a reduction in lipid accumulation and the expression of PPARγ (Peroxisome proliferator-activated receptor γ) and C/EBPα (CCAAT enhancer binding protein α). Significant activation of AMPK (AMP-activated protein kinase), increased expression of GLUT4 (Glucose Transporter Type 4), and inhibition of α-glucosidase activity were also observed. These findings provide the basis for the anti-obesity and anti-diabetic effects of OKE. In addition, OKE has a significant antioxidant effect. This study presents OKE as a potential natural product-derived material for the treatment of patients with metabolic diseases such as obesity- and obesity-induced diabetes.

Betaine ameliorates doxorubicin-induced cardiomyopathy by inhibiting oxidative stress, inflammation, and fibrosis through the modulation of AMPK/Nrf2/TGF-β expression.

Doxorubicin (DOX) is a broad-spectrum antibiotic with potent anti-cancer activity. Nevertheless, despite having effective anti-neoplasm activity, its use has been clinically restricted due to its life-threatening side effects, such as cardiotoxicity. It is evident that betaine has anti-oxidant, and anti-inflammatory activity and has several beneficial effects, such as decreasing the amyloid-β generation, reducing obesity, improving steatosis and fibrosis, and activating AMP-activated protein kinase (AMPK). However, whether betaine could mitigate DOX-induced cardiomyopathy is still unexplored. Cardiomyopathy was induced in male Sprague Dawley rats using DOX (4 mg/kg dose with a cumulative dose of 20 mg/kg, i.p.). Further, betaine (200 and 400 mg/kg) was co-treated with DOX through oral gavage for 28 days. After the completion of the study, several biochemical, oxidative stress parameters, histopathology, western blotting, and qRT-PCR were performed. Betaine treatment significantly reduced CK-MB, LDH, SGOT, and triglyceride levels, which are associated with cardiotoxicity. DOX-induced increased oxidative stress was also mitigated by betaine intervention as the SOD, catalase, MDA, and nitrite levels were restored. The histopathological investigation also confirmed the cardioprotective effect of betaine against DOX-induced cardiomyopathy as the tissue injury was reversed. Further, molecular analysis revealed that betaine suppressed the DOX-induced increased expression of phospho-p53, phospho-p38 MAPK, NF-kB p65, and PINK 1 with an upregulation of AMPK and downregulation of Nrf2 expression. Interestingly, qRT-PCR experiments show that betaine treatment alleviates the DOX-induced increase in inflammatory (TNF-α, NLRP3, and IL-6) and fibrosis (TGF-β and Acta2) related gene expression, halting the cardiac injury. Interestingly, betaine also improves the mRNA expression of Nrf2, thus modulating the expression of antioxidant proteins and preventing oxidative damage. Here, we provide the first evidence that betaine treatment prevents DOX-induced cardiomyopathy by inhibiting oxidative stress, inflammation, and fibrosis by regulating AMPK/Nrf2/TGF-β expression. We believe that betaine can be utilized as a potential novel therapeutic strategy for preventing DOX-induced cardiotoxicity.

Loss of AMPK activity induces organelle dysfunction and oxidative stress during oocyte aging

BackgroundOocyte quality is critical for the mammalian reproduction due to its necessity on fertilization and early development. During aging, the declined oocytes showing with organelle dysfunction and oxidative stress lead to infertility. AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase which is important for energy homeostasis for metabolism. Little is known about the potential relationship between AMPK with oocyte aging.ResultsIn present study we reported that AMPK was related with low quality of oocytes under post ovulatory aging and the potential mechanism. We showed the altered AMPK level during aging and inhibition of AMPK activity induced mouse oocyte maturation defect. Further analysis indicated that similar with its upstream regulator PKD1, AMPK could reduce ROS level to avoid oxidative stress in oocytes, and this might be due to its regulation on mitochondria function, since loss of AMPK activity induced abnormal distribution, reduced ATP production and mtDNA copy number of mitochondria. Besides, we also found that the ER and Golgi apparatus distribution was aberrant after AMPK inhibition, and enhanced lysosome function was also observed.ConclusionsTaken together, these data indicated that AMPK is important for the organelle function to reduce oxidative stress during oocyte meiotic maturation.

Mitochondrial energy state controls AMPK-mediated foraging behavior in C. elegans.

Organisms surveil and respond to their environment using behaviors entrained by metabolic cues that reflect food availability. Mitochondria act as metabolic hubs and at the center of mitochondrial energy production is the protonmotive force (PMF), an electrochemical gradient generated by metabolite consumption. The PMF serves as a central integrator of mitochondrial status, but its role in governing metabolic signaling is poorly understood. We used optogenetics to dissipate the PMF in Caenorhabditis elegans tissues to test its role in food-related behaviors. Our data demonstrate that PMF reduction in the intestine is sufficient to initiate locomotor responses to acute food deprivation. This behavioral adaptation requires the cellular energy regulator AMP-activated protein kinase (AMPK) in neurons, not in the intestine, and relies on mitochondrial dynamics and axonal trafficking. Our results highlight a role for intestinal PMF as an internal metabolic cue, and we identify a bottom-up signaling axis through which changes in the PMF trigger AMPK activity in neurons to promote foraging behavior.

Roles of β-Cell Hypoxia in the Progression of Type 2 Diabetes.

Type 2 diabetes is a chronic disease marked by hyperglycemia; impaired insulin secretion by pancreatic β-cells is a hallmark of this disease. Recent studies have shown that hypoxia occurs in the β-cells of patients with type 2 diabetes and hypoxia, in turn, contributes to the insulin secretion defect and β-cell loss through various mechanisms, including the activation of hypoxia-inducible factors, induction of transcriptional repressors, and activation of AMP-activated protein kinase. This review focuses on advances in our understanding of the contribution of β-cell hypoxia to the development of β-cell dysfunction in type 2 diabetes. A better understanding of β-cell hypoxia might be useful in the development of new strategies for treating type 2 diabetes.

Dietary fat supplementation relieves cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis in pigs.

Cold stress has negative effects on the growth and health of mammals, and has become a factor restricting livestock development at high latitudes and on plateaus. The gut-liver axis is central to energy metabolism, and the mechanisms by which it regulates host energy metabolism at cold temperatures have rarely been illustrated. In this study, we evaluated the status of glycolipid metabolism and oxidative stress in pigs based on the gut-liver axis and propose that AMP-activated protein kinase (AMPK) is a key target for alleviating energy stress at cold temperatures by dietary fat supplementation. Dietary fat supplementation alleviated the negative effects of cold temperatures on growth performance and digestive enzymes, while hormonal homeostasis was also restored. Moreover, cold temperature exposure increased glucose transport in the jejunum. In contrast, we observed abnormalities in lipid metabolism, which was characterized by the accumulation of bile acids in the ileum and plasma. In addition, the results of the ileal metabolomic analysis were consistent with the energy metabolism measurements in the jejunum, and dietary fat supplementation increased the activity of the mitochondrial respiratory chain and lipid metabolism. As the central nexus of energy metabolism, the state of glycolipid metabolism and oxidative stress in the liver are inconsistent with that in the small intestine. Specifically, we found that cold temperature exposure increased glucose transport in the liver, which fully validates the idea that hormones can act on the liver to regulate glucose output. Additionally, dietary fat supplementation inhibited glucose transport and glycolysis, but increased gluconeogenesis, bile acid cycling, and lipid metabolism. Sustained activation of AMPK, which an energy receptor and regulator, leads to oxidative stress and apoptosis in the liver; dietary fat supplementation alleviates energy stress by reducing AMPK phosphorylation. Cold stress reduced the growth performance and aggravated glycolipid metabolism disorders and oxidative stress damage in pigs. Dietary fat supplementation improved growth performance and alleviated cold temperature-induced energy stress through AMPK-mediated mitochondrial homeostasis. In this study, we highlight the importance of AMPK in dietary fat supplementation-mediated alleviation of host energy stress in response to environmental changes.

Hydrangea paniculata coumarins alleviate adriamycin-induced renal lipotoxicity through activating AMPK and inhibiting C/EBPβ

Ethnopharmacological relevanceThroughout Chinese history, Hydrangea paniculata Siebold has been utilized as a traditional medicinal herb to treat a variety of ailments associated to inflammation. In a number of immune-mediated kidney disorders, total coumarins extracted from Hydrangea paniculata (HP) have demonstrated a renal protective effect. Aim of the studyTo investigate renal beneficial effect of HP on experimental Adriamycin nephropathy (AN), and further clarify whether reversing lipid metabolism abnormalities by HP contributes to its renoprotective effect and find out the underlying critical pathways. Materials and methodsAfter establishment of rat AN model, HP was orally administrated for 6 weeks. Biochemical indicators related to kidney injury were determined. mRNAs sequencing using kidney tissues were performed to clarify the underlying mechanism. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis, western blot, molecular docking, and drug affinity responsive target stability (DARTS) assay was carried out to further explore and confirm pivotal molecular pathways and possible target by which HP and 7-hydroxylcoumarin (7-HC) played their renal protection effect via modulating lipid metabolism. ResultsHP could significantly improve renal function, and restore renal tubular abnormal lipid metabolism and interstitial fibrosis in AN. In vitro study demonstrated that HP and its main metabolite 7-HC could reduce ADR-induced intracellular lipid deposition and fibrosis characteristics in renal tubular cells. Mechanically, HP and 7-HC can activate AMP-activated protein kinase (AMPK) via direct interaction, which contributes to its lipid metabolism modulation effect. Moreover, HP and 7-HC can inhibit fibrosis by inhibiting CCAAT/enhancer binding protein beta (C/EBPβ) expression in renal tubular cells. Normalization of lipid metabolism by HP and 7-HC further provided protection of mitochondrial structure integrity and inhibited the nuclear factor kappa-B (NF-κB) pathway. Long-term toxicity using beagle dogs proved the safety of HP after one-month administration. ConclusionCoumarin derivates from HP alleviate adriamycin-induced lipotoxicity and fibrosis in kidney through activating AMPK and inhibiting C/EBPβ.

AMPK restricts HHV-6A replication by inhibiting glycolysis and mTOR signaling

AMP-activated protein kinase (AMPK) is a cellular energy sensor regulating metabolic homeostasis. In this study, we investigated the role of AMPK in response to human herpesvirus 6A (HHV-6A) infection. We show that HHV-6A infection significantly downregulates the active phosphorylated state of AMPK in infected T cells. Pharmacological activation of AMPK highly attenuated HHV-6A propagation. Mechanistically, we found that the activation of AMPK by AICAR blocked HHV-6-induced glycolysis by inhibiting glucose metabolism and lactate secretion, as well as decreasing expressions of key glucose transporters and glycolytic enzymes. In addition, mTOR signaling has been inactivated in HHV-6A infected T cells by AICAR treatment. We also showed that HHV-6A infection of human umbilical cord blood mononuclear cells (CBMCs) reduced AMPK activity whereas the activation of AMPK by metformin drastically reduced HHV-6A DNA replication and virions production. Taken together, this study demonstrates that AMPK is a promising antiviral therapeutic target against HHV-6A infection.

Multiple metabolic signals in the CeA regulate feeding: The role of AMPK

BackgroundThe central nucleus of the amygdala (CeA) is part of the dopaminergic reward system and controls energy balance. Recently, a cluster of neurons was identified as responsive to the orexigenic effect of ghrelin and fasting. However, the signaling pathway by which ghrelin and fasting induce feeding is unknown. AMP-activated protein kinase (AMPK) is a cellular energy sensor, and its Thr172 phosphorylation (AMPKThr172) in the mediobasal hypothalamus regulates food intake. However, whether the expression and activation of AMPK in CeA could be one of the intracellular signaling activated in response to ghrelin and fasting eliciting food intake is unknown. AimTo evaluate the activation of AMPK into CeA in response to ghrelin, fasting, and 2-deoxy-D-glucose (2DG) and whether feeding accompanied these changes. In addition, to investigate whether the inhibition of AMPK into CeA could decrease food intake. MethodsOn a chow diet, eight-week-old Wistar male rats were stereotaxically implanted with a cannula in the CeA to inject several modulators of AMPKα1/2Thr172 phosphorylation, and we performed physiological and molecular assays. Key findingsFasting increased, and refeeding reduced AMPKThr172 in the CeA. Intra-CeA glucose injection decreased feeding, whereas injection of 2DG, a glucoprivation inductor, in the CeA, increased food intake and blood glucose, despite faint increases in AMPKThr172. Intra-CeA ghrelin injection increased food intake and AMPKThr172. To further confirm the role of AMPK in the CeA, chronic injection of Melanotan II (MTII) in CeA reduced body mass and food intake over seven days together with a slight decrease in AMPKThr172. SignificanceOur findings identified that AMPK might be part of the signaling machinery in the CeA, which responds to nutrients and hormones contributing to feeding control. The results can contribute to understanding the pathophysiological mechanisms of altered feeding behavior/consumption, such as binge eating of caloric-dense, palatable food.

Metformin for sepsis-associated AKI: a protocol for the Randomized Clinical Trial of the Safety and FeasibiLity of Metformin as a Treatment for sepsis-associated AKI (LiMiT AKI)

IntroductionAcute kidney injury (AKI) is a common complication of sepsis associated with increased risk of death. Preclinical data and observational human studies suggest that activation of AMP-activated protein kinase, an...

AMPK activation modulates IL-36-induced inflammatory responses by regulating IκBζ expression in the skin.

The interleukin (IL)-36 pathway is a critical player in the pathogenesis of pustular psoriasis. However, therapies targeting this pathway are limited or unaffordable (e.g. the anti-IL-36 receptor antibody). AMP-activated protein kinase (AMPK), a regulator of cellular energy and metabolism, is known to participate in inflammatory diseases. However, its role in IL-36-induced skin inflammation remains unclear. Therefore, we sought to investigate the role of AMPK signals in regulating IL-36-induced responses in the skin. IL-36-stimulated primary normal human epidermal keratinocytes (NHEKs) and IL-36-injected (intradermally) BALB/c mice served as the cell and animal models, respectively. Additionally, 5-aminoimidazole-4-carboxamide riboside (AICAR) and A769662 served as AMPK activators. AICAR and A769662 significantly suppressed the IL-36-induced IL-8 (CXCL8) and CCL20 production from NHEKs. IL-36-induced IκBζ protein expression was prominently reduced and IKK/IκBα phosphorylation was attenuated by AICAR and A769662. Conversely, AMPKα knockdown increased IκBζ protein expression and IKK/IκBα phosphorylation in IL-36-treated NHEKs. Furthermore, AICAR and A769662 enhanced IL-36-induced-IκBζ protein degradation via the proteasome-dependent but not the lysosome-dependent pathway. Pretreatment of NHEKs with IL-36 slightly suppressed the AICAR- and A769662-triggered phosphorylation of AMPK and acetyl-CoA carboxylase. In the mouse model, topical application of AICAR significantly reduced ear swelling, redness, epidermal thickening, neutrophil infiltration and inflammatory and antimicrobial peptide gene expression. AMPK activation suppresses IL-36-induced IL-8 and CCL20 release by regulating IκBζ expression in keratinocytes and reduces IL-36-induced skin inflammation in mice, suggesting that AMPK activation is a potential strategy for treating patients with IL-36-mediated inflammatory skin disorders.

Abstract 5116: Stress-induced AMPK interactome analysis reveals novel protein-protein interactions associated with chromatin remodeling in acute lymphoblastic leukemia

Abstract Acute lymphoblastic leukemia (ALL) is a leading cause of cancer-related death among children, adolescents and young adults. We previously reported that ALL cells are vulnerable to metabolic stress conditions following AMP-activated protein kinase (AMPK) activation, leading to cell death. AMPK is the master metabolic regulator, and we and others have reported it interacts with chromatin-associated proteins to regulate gene expression in response to metabolic stress. To investigate AMPK’s mechanistic role in epigenetic gene regulation under metabolic stress, and identify new AMPK partners, we performed a comprehensive interactome analysis using TurboID-based proximity labeling proteomics. We generated HEK293T cells stably expressing TurboID fused to the AMPKα1, AMPKα2, AMPKβ1 or AMPKγ1. Following treatment with the allosteric AMPK activator PF-06409577 (PF064) for 1h, to mimic the cell’s rapid response to energy/metabolic stress, the samples underwent mass spectrometry-based proteomics. Proteomics data analysis identified novel altered (enhanced or reduced) AMPK protein-protein interactions (PPI) following PF064 treatment. The GO analysis of proteins interacting with AMPK showed that metabolic stress enhances PPIs involved in regulating gene expression, cellular metabolic processes, DNA repair, chromatin organization, histone modifications, etc. More importantly, we identified that AMPK interacted with members of the non-canonical Polycomb repressive complex 1 (PRC1.1) such as PCGF1, RING1, KDM2B, BCORL1, USP7. PRC1 is a known epigenetic regulator that monoubiquitinylates histone H2A at Lys119 (H2AK119ub) to control transcription and regulate gene expression. Using Co-IP, we confirmed these interactions in KASUMI-2 (Bp-ALL) and KE-37 (T-ALL) cells. When cells were treated with PF064 or 991 (another AMPK activator), we found that the interactions of AMPK with the catalytic core of PCR1.1 (PCGF1, RING1) were increased compared to untreated cells. To examine the effect of activated AMPK on PCR1.1 activity, we determined the level of H2AK119ub in ALL cells treated with PF064 and 991 for 1h. We found that the level of H2AK119ub protein expression was increased in ALL-treated cells indicating the PRC1.1 was activated. Together, these data suggest that stress-induced AMPK activation increased the catalytic activity of the PRC1.1 via PPI in ALL. Our findings are consistent with our previous published RNA-Seq and ChIP-Seq data indicating an epigenetic role for AMPK in altering gene expression examined under metabolic stress (two thirds exhibited downregulation), and provide insights into the AMPK-driven mechanism(s) involved. Further elucidation of the uncovered PPIs and its mechanistic role(s) may lead to potential epigenetic-based strategies to overcome resistance/refractoriness in ALL and other malignancies. Citation Format: Anna Shvab, Guy J. Leclerc, Julio C. Barredo. Stress-induced AMPK interactome analysis reveals novel protein-protein interactions associated with chromatin remodeling in acute lymphoblastic leukemia [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5116.

Abstract 3079: AMPK-HIF-1α signaling enhances glucose-derived de novoserine biosynthesis to promote glioblastoma growth

Abstract Cancer cells undergo cellular adaptation through metabolic reprogrammin to sustain survival and rapid growth under various stress conditions. However, it remains unknown how brain tumors modulate their metabolic flexibility in the naturally serine/glycine (S/G)-deficient brain microenvironment. We used a range of primary/stem-like and established glioblastoma (GBM) cell models in vitro and in vivo. To identify regulatory mechanisms of S/G deprivation induced metabolic flexibility, we employed high throughput RNA-sequencing, transcriptomic analysis, metabolic flux analysis, metabolites analysis, chromatin immunoprecipitation (ChIP), luciferase reporter, nuclear fractionation, cycloheximide-chase, and glucose consumption. The clinical significances were analyzed in the genomic database (GSE4290) and in human GBM specimens. The high throughput RNA-sequencing and transcriptomic analysis demonstrate that the de novo serine synthesis pathway (SSP) and glycolysis are highly activated in GBM cells under S/G deprivation conditions. Mechanistically, S/G deprivation rapidly induces reactive oxygen species (ROS)-mediated AMP-activated protein kinase (AMPK) activation and AMPK dependent hypoxia-inducible factor (HIF)-1α stabilization and transactivation. Activated HIF-1α in turn promotes expression of SSP enzymes phosphoglycerate dehydrogenase (PHGDH), phosphoserine aminotransferase 1 (PSAT1), and phosphoserine phosphatase (PSPH). In addition, HIF-1α-induced expression of glycolytic genes (GLUT1, GLUT3, HK2, and PFKFB2) promotes glucose uptake, glycolysis, and glycolytic flux to fuel SSP, leading to elevated de novo serine and glycine biosynthesis, NADPH/NADP+ ratio, and proliferation and survival of GBM cells. Analyses of human GBM specimens reveal that levels of overexpressed PHGDH, PSAT1, and PSPH are positively correlated with levels of AMPK T172 phosphorylation and HIF-1α expression and poor prognosis of GBM patients. Our findings reveal that metabolic stress-enhanced glucose-derived de novo serine biosynthesis is a critical metabolic feature of GBM cells and highlight the potential to target SSP for treating human GBM. Citation Format: Hye Jin Yun, Jong-Ho Lee. AMPK-HIF-1α signaling enhances glucose-derived de novoserine biosynthesis to promote glioblastoma growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3079.