AMP-activated Protein Kinase Activation Research Articles

Exercise training adaptations in liver glycogen and glycerolipids require hepatic AMP-activated protein kinase in mice.

Regular exercise elicits adaptations in glucose and lipid metabolism that allow the body to meet energy demands of subsequent exercise bouts more effectively and mitigate metabolic diseases including fatty liver. Energy discharged during the acute exercise bouts that comprise exercise training may be a catalyst for liver adaptations. During acute exercise, liver glycogenolysis and gluconeogenesis are accelerated to supply glucose to working muscle. Lower liver energy state imposed by gluconeogenesis and related pathways activates AMP-activated protein kinase (AMPK), which conserves ATP partly by promoting lipid oxidation. This study tested the hypothesis that AMPK is necessary for liver glucose and lipid adaptations to training. Liver-specific AMPKα1α2 knockout (AMPKα1α2fl/fl+AlbCre) mice and littermate controls (AMPKα1α2fl/fl) completed sedentary and exercise training protocols. Liver nutrient fluxes were quantified at rest or during acute exercise following training. Liver metabolites and molecular regulators of metabolism were assessed. Training increased liver glycogen in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. The inability to increase glycogen led to lower glycogenolysis, glucose production, and circulating glucose during acute exercise in trained AMPKα1α2fl/fl+AlbCre mice. Deletion of AMPKα1α2 attenuated training-induced declines in liver diacylglycerides. In particular, training lowered the concentration of unsaturated and elongated fatty acids comprising diacylglycerides in AMPKα1α2fl/fl mice, but not in AMPKα1α2fl/fl+AlbCre mice. Training increased liver triacylglycerides and the desaturation and elongation of fatty acids in triacylglycerides of AMPKα1α2fl/fl+AlbCre mice. These lipid responses were independent of differences in tricarboxylic acid cycle fluxes. In conclusion, AMPK is required for liver training adaptations that are critical to glucose and lipid metabolism.NEW & NOTEWORTHY This study shows that the energy sensor and transducer, AMP-activated protein kinase (AMPK), is necessary for an exercise training-induced: 1) increase in liver glycogen that is necessary for accelerated glycogenolysis during exercise, 2) decrease in liver glycerolipids independent of tricarboxylic acid (TCA) cycle flux, and 3) decline in the desaturation and elongation of fatty acids comprising liver diacylglycerides. The mechanisms defined in these studies have implications for use of regular exercise or AMPK-activators in patients with fatty liver.

AMPK activator-treated human cardiac spheres enhance maturation and enable pathological modeling

BackgroundCardiac pathological outcome of metabolic remodeling is difficult to model using cardiomyocytes derived from human-induced pluripotent stem cells (hiPSC-CMs) due to low metabolic maturation.MethodshiPSC-CM spheres were treated with AMP-activated protein kinase (AMPK) activators and examined for hiPSC-CM maturation features, molecular changes and the response to pathological stimuli.ResultsTreatment of hiPSC-CMs with AMPK activators increased ATP content, mitochondrial membrane potential and content, mitochondrial DNA, mitochondrial function and fatty acid uptake, indicating increased metabolic maturation. Conversely, the knockdown of AMPK inhibited mitochondrial maturation of hiPSC-CMs. In addition, AMPK activator-treated hiPSC-CMs had improved structural development and functional features—including enhanced Ca2+ transient kinetics and increased contraction. Transcriptomic, proteomic and metabolomic profiling identified differential levels of expression of genes, proteins and metabolites associated with a molecular signature of mature cardiomyocytes in AMPK activator-treated hiPSC-CMs. In response to pathological stimuli, AMPK activator-treated hiPSC-CMs had increased glycolysis, and other pathological outcomes compared to untreated cells.ConclusionAMPK activator-treated cardiac spheres could serve as a valuable model to gain novel insights into cardiac diseases.

Improved endurance capacity of diabetic mice during SGLT2 inhibition: Role of AICARP, an AMPK activator in the soleus.

Diabetes is associated with an increased risk of deleterious changes in muscle mass and function or sarcopenia, leading to physical inactivity and worsening glycaemic control. Given the negative energy balance during sodium-glucose cotransporter-2 (SGLT2) inhibition, whether SGLT2 inhibitors affect skeletal muscle mass and function is a matter of concern. However, how SGLT2 inhibition affects the skeletal muscle function in patients with diabetes remains insufficiently explored. We aimed to explore the effects of canagliflozin (CANA), an SGLT2 inhibitor, on skeletal muscles in genetically diabetic db/db mice focusing on the differential responses of oxidative and glycolytic muscles. Db/db mice were treated with CANA for 4weeks. We measured running distance and handgrip strength to assess skeletal muscle function during CANA treatment. At the end of the experiment, we performed a targeted metabolome analysis of the skeletal muscles. CANA treatment improved the reduced endurance capacity, as revealed by running distance in db/db mice (414.9±52.8 vs. 88.7±22.7m, P<0.05). Targeted metabolome analysis revealed that 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranosyl 5'-monophosphate (AICARP), a naturally occurring AMP-activated protein kinase (AMPK) activator, increased in the oxidative soleus muscle (P<0.05), but not in the glycolytic extensor digitorum longus muscle (P=0.4376), with increased levels of AMPK phosphorylation (P<0.01). This study highlights the potential role of the AICARP/AMPK pathway in oxidative rather than glycolytic skeletal muscles during SGLT2 inhibition, providing novel insights into the mechanism by which SGLT2 inhibitors improve endurance capacity in patients with type 2 diabetes.

Metformin-Loaded Hyaluronic Acid-Derived Carbon Dots for Targeted Therapy against Hepatocellular Carcinoma by Glutamine Metabolic Reprogramming.

Metabolic reprogramming is a significant hallmark of cancer that promotes chemoresistance by allowing tumor tissues to adapt to changes in the tumor microenvironment caused by anticancer therapies. Hepatocellular carcinoma (HCC), one of the most common types of primary tumors, is associated with recurrent metabolic reprogramming that maximizes cancer cell growth and proliferation. Herein, we developed metformin (MET)-loaded hyaluronic acid (HA)-derived carbon dots (HA-CD-MET) by a simple and green method with no involvement of any additives. HA-CD-MET was utilized for specifically binding the CD44 receptor overexpressed in HCC and induced glutamine metabolic rewiring to inhibit HCC cell proliferation. Exposure to HA-CD-MET resulted in ∼6.5-fold better anticancer efficacy against CD44+ Hep3B cells in comparison to CD44-, HepG2, and noncancerous HEK293 cells at a very low dose of 80 μg/mL. Moreover, treatment of three-dimensional (3D) tumor spheroid model of HCC (Hep3B) with HA-CD-MET resulted in ∼4.9-fold reduction in tumor size. This improved anticancer efficacy of HA-CD-MET was attributed to the inhibition of glutaminase-1 (GLS-1), a mitochondrial enzyme that hydrolyzes glutamine into glutamate as confirmed from immunofluorescence and immunoblotting experiments. Furthermore, treatment with HA-CD-MET resulted in downregulation of glucose transporter-1 (GLUT-1) in Hep3B cells. Consequently, cancer cells were starved from essential nutrients, glutamine, and glucose, leading to the enhancement in intracellular ROS generation. This increase in intracellular ROS accumulation activated AMP-activated protein kinase (AMPK) and inhibited AKT phosphorylation, leading to cancer cell apoptosis. Thus, this study offers the targeting of metabolic reprogramming by HA-CD-MET that opens up a promising strategy for therapeutic intervention in hepatocarcinoma.

Abstract 15747: AMPK Cysteine Oxidation by SOD3-Derived H 2 O 2 Mediates Exercise-Induced Restoration of Skeletal Muscle Angiogenesis in Type2 Diabetes

Background: Exercise restores decreased capillary density in skeletal muscle (SKM) (capillary rarefaction) in type2 diabetes (T2D) that has eNOS uncoupling/excess O 2 - , which is required for treatment of diabetic peripheral vascular disease (PAD) via unknown mechanisms. AMP-activated protein kinase (AMPK) is a key angiogenic/metabolic kinase mainly regulated by phosphorylation and is required for baseline, but not exercise-induced capillary density in SKM under healthy conditions. AMPK senses H 2 O 2 signal to increase its activity via oxidative modification of Cys299/304 in vitro. In addition, extracellular SOD (SOD3) that catalyzes the dismutation of O 2 - to H 2 O 2 is increased in response to exercise. However, the role of AMPK and SOD3 in exercise-induced SKM angiogenesis in T2D has not been reported. Oxidation of Cysteine residues to generate cysteine sulfenic acid (Cys-OH) is a key event in H 2 O 2 -mediated signaling. Results: Here we show that reduced CD31+ capillary density in SKM of high fat diet-induced T2D mice was restored (2.4-fold) by voluntary wheel exercise training (2 weeks) with enhanced SOD3 activity (224%) and extracellular H 2 O 2 levels (3.2-fold). Of note, exercise in T2D mice increased AMPK activity (by p-ACC) via inducing CysOH formation of AMPK (3.6-fold), but not p-AMPK induction, which was inhibited by SOD3 -/- /T2D mice that reduced exercise-induced H 2 O 2 . To demonstrate functional significance of AMPK Cys oxidation, we generated CRISPR/Cas9-genome editing “redox-dead” AMPK-Cys299/304Ala (AMPK-C/A) knock-in (KI) mutant mice and found that AMPK-C/A KI mice showed significant inhibition of exercise-induced angiogenesis (44%) via reducing angiogenic PGC1α and VEGF protein expression in SKM of T2D mice. In vitro, C2C12 skeletal muscles overexpressing SOD3 treated with palmitate (mimic T2D with exercise) induced AMPK-CysOH formation and VEGF secretion. Its conditioned media promoted angiogenic responses such as EC migration (1.8-fold) and tube formation (1.7-fold), which was inhibited by C2C12 cells overexpressing AMPK C/A mutant. Conclusion: Novel exercise-induced AMPK CysOH formation at Cys299/304 restores angiogenesis in SKM of T2D via SOD3-mediated H 2 O 2 , which may contribute to revascularization in diabetic PAD.

Enhanced fatty acid oxidation through metformin and baicalin as therapy for COVID-19 and associated inflammatory states in lung and kidney

Progressive respiratory failure is the primary cause of death in the coronavirus disease 2019 (COVID-19) pandemic. It is the final outcome of the acute respiratory distress syndrome (ARDS), characterized by an initial exacerbated inflammatory response, metabolic derangement and ultimate tissue scarring. A positive balance of cellular energy may result crucial for the recovery of clinical COVID-19. Hence, we asked if two key pathways involved in cellular energy generation, AMP-activated protein kinase (AMPK)/acetyl-CoA carboxylase (ACC) signaling and fatty acid oxidation (FAO) could be beneficial. We tested the drugs metformin (AMPK activator) and baicalin (CPT1A activator) in different experimental models mimicking COVID-19 associated inflammation in lung and kidney. We also studied two different cohorts of COVID-19 patients that had been previously treated with metformin. These drugs ameliorated lung damage in an ARDS animal model, while activation of AMPK/ACC signaling increased mitochondrial function and decreased TGF-β-induced fibrosis, apoptosis and inflammation markers in lung epithelial cells. Similar results were observed with two indole derivatives, IND6 and IND8 with AMPK activating capacity. Consistently, a reduced time of hospitalization and need of intensive care was observed in COVID-19 patients previously exposed to metformin. Baicalin also mitigated the activation of pro-inflammatory bone marrow-derived macrophages (BMDMs) and reduced kidney fibrosis in two animal models of kidney injury, another key target of COVID-19. In human epithelial lung and kidney cells, both drugs improved mitochondrial function and prevented TGF-β-induced renal epithelial cell dedifferentiation. Our results support that favoring cellular energy production through enhanced FAO may prove useful in the prevention of COVID-19-induced lung and renal damage.

Maackiain suppresses the development of cervical cancer via AMPK priming autophagy.

Maackiain (Mac), a flavonoid analog isolated from Sophora flavescens, exhibits neuroprotective, anti-allergic, anti-inflammatory, and pro-apoptotic effects. It is not clear whether Mac has a therapeutic effect on cervical cancer. In this work, we used RT-qPCR, western blot, immunofluorescence, and related methods to detect the therapeutic mechanism of Mac for cervical cancer. We demonstrated that Mac significantly inhibited the proliferation, migration, and invasion of human cervical cancer cell lines HeLa and SiHa. And, Mac enhanced the pro-apoptotic effects of cisplatin in treating cervical cancer cells. Mac has shown good efficacy in treating cervical cancer. Furthermore, Mac inhibited the mammalian target of the rapamycin (mTOR) pathway, thereby inducing autophagy in cervical cancer cells. The regulation of mTOR/autophagy pathway by Mac relied on the activation of AMP-activated protein kinase (AMPK), and the inhibition of the AMPK reversed the Mac's anti-cervical cancer activity. In addition, experimental study of Mac in mouse xenograft tumor model further confirmed its good anti-cervical cancer activity. Mac inhibits human cervical cancer by activating the AMPK/mTOR/autophagy pathway, indicating that it is a potential natural compound for the treatment of cervical cancer. This study also provides a feasible molecular mechanism for the treatment of cervical cancer.

AMPK Controls Glycolytic Compensation in Gvhd-Causing T Cells

Background: The heightened metabolic requirements of alloreactive T cells following allogeneic stem cell transplantation represents a promising area for therapeutic intervention. We have shown that during the initiation of acute graft-versus-host-disease (aGVHD), murine T cells upregulate activity of AMP-activated protein kinase (AMPK), a cellular energy sensor that regulates oxidative and mitochondrial metabolism. Further, transfer of allogeneic T cells deficient in AMPK (AMPK KO) increased recipient survival and decreased disease severity while still preserving leukemia clearance. In the current studies, we demonstrate a novel role for AMPK in controlling glycolytic compensation, both in vitro and vivo, and provide a mechanism as to why cells lacking AMPK are unable to perform this vital function. Together, these data highlight the potential clinical utility in targeting metabolic decision-making to curtail T cell-mediated inflammatory responses, with significant therapeutic implications for the prevention and treatment of aGVHD. Methods: AMPK-deficient murine T cells from AMPKa1/a2 dKO C57BL/6J mice were transplanted into allogeneic B6D2F1 recipients and recovered on day 7 post-transplant. To delete AMPK in primary human T cells, T cells were isolated from healthy donors and electroporated with Cas 9 ribonucleoprotein complexes targeting the AMPKa1 locus. Glycolytic compensation was assessed by measuring extracellular acidification rates (ECAR) using the Agilent Seahorse analyzer and a mitochondrial stress kit. Intracellular cytokine expression for IFNgamma was assessed in day 7 murine T cells following re-stimulation with F1 splenocytes in the presence of Brefeldin A. Aldolase A and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) enzymatic assays were run on cell lysates with Biovision-Abcam kits according to manufacturer instructions. To measure GAPDH activity, T cells were positively selected for CD45.1 from day 7 recipient spleens, followed by cell lysis and detection of enzymatic activity. Results: AMPK KO murine T cells recovered on day 7 were unable to mediate a compensatory increase in glycolysis following inhibition of the electron transport chain (Figure 1A), (-6.499±5.156 vs 29.11±7.064, p&amp;lt;0.0001). Human T cells lacking AMPK gave similar results, with glycolytic compensation impaired both in vitro and following human T cell expansion in vivo in a xenogeneic model of GVHD. Immunoprecipitation of proteins from day 7 murine T cells, using an antibody specific to phosphorylated AMPK targets, recovered lower levels of multiple glycolytic enzymes including aldolase, enolase, pyruvate kinase M, and GAPDH (Figure 1B). Functionally, murine T cells lacking AMPK exhibited impaired aldolase activity following anti-CD3/CD28 stimulation and a decrease in GAPDH activity on day 7 post-transplant. Importantly, these changes in glycolysis correlated with an impaired ability of AMPK KO T cells to produce significant amounts of IFNγ upon antigenic re-stimulation with F1 splenocytes. Discussion: Our results demonstrate that in addition to influencing oxidative metabolism, AMPK also plays a role in glycolytic metabolism during GVHD in both murine and human T cells. Further, our data suggest that the more prominent lesion in human T cells post-transplant was in glycolysis , a result supported by the novel observation that a set of glycolysis-related proteins are immunoprecipitated together at much lower rates in the absence of AMPK. These findings suggest a model in which AMPK phosphorylation provides a nidus for important interactions among glycolytic enzymes and that in the absence of AMPK, these interactions are lessened, and glycolysis is consequently reduced. Important to our understanding of GVHD pathogenesis, rates of T cell glycolysis can be directly linked to IFNγ production, where reduced glycolytic activity frees GAPDH to sequester IFNγ transcripts and thereby limit IFNγ protein translation. Altogether, these results document a prominent role for AMPK in controlling T cell glycolytic activity during GVHD development and offer an additional mechanistic explanation for the decreased severity of GVHD seen following transplantation of AMPK KO T cells. Consistently similar results in human xenogeneic T cells provides a further strong rationale for development of AMPK inhibition as a clinically translatable strategy for GVHD prevention and treatment.

Quercetin and AMPK: A Dynamic Duo in Alleviating MG-Induced Inflammation via the AMPK/SIRT1/NF-κB Pathway.

Mycoplasma gallisepticum (MG) is recognized as a principal causative agent of avian chronic respiratory disease, inflicting substantial economic losses upon the poultry industry. However, the extensive use of conventional antibiotics has resulted in the emergence of drug resistance and various challenges in their clinical application. Consequently, there is an urgent need to identify effective therapeutic agents for the prevention and treatment of mycoplasma-induced respiratory disease in avian species. AMP-activated protein kinase (AMPK) holds significant importance as a regulator of cellular energy metabolism and possesses the capacity to exert an anti-inflammatory effect by virtue of its downstream protein, SIRT1. This pathway has shown promise in counteracting the inflammatory responses triggered by pathogenic infections, thus providing a novel target for studying infectious inflammation. Quercetin possesses anti-inflammatory activity and has garnered attention as a potential alternative to antibiotics. However, there exists a gap in knowledge concerning the impact of this activation on MG-induced inflammatory damage. To address this knowledge gap, we employed AlphaFold2 prediction, molecular docking, and kinetic simulation methods to perform a systematic analysis. As expected, we found that both quercetin and the AMPK activator AICAR activate the chicken AMPKγ1 subunit in a similar manner, which was further validated at the cellular level. Our project aims to unravel the underlying mechanisms of quercetin's action as an agonist of AMPK against the inflammatory damage induced by MG infection. Accordingly, we evaluated the effects of quercetin on the prevention and treatment of air sac injury, lung morphology, immunohistochemistry, AMPK/SIRT1/NF-κB pathway activity, and inflammatory factors in MG-infected chickens. The results confirmed that quercetin effectively inhibits the secretion of pro-inflammatory cytokines such as IL-1β, TNF-α, and IL-6, leading to improved respiratory inflammation injury. Furthermore, quercetin was shown to enhance the levels of phosphorylated AMPK and SIRT1 while reducing the levels of phosphorylated P65 and pro-inflammatory factors. In conclusion, our study identifies the AMPK cascade signaling pathway as a novel cellular mediator responsible for quercetin's ability to counter MG-induced inflammatory damage. This finding highlights the potential significance of this pathway as an important target for anti-inflammatory drug research in the context of avian respiratory diseases.

Calcium signals tune AMPK activity and mitochondrial homeostasis in dendrites of developing neurons.

Dendritic outgrowth in immature neurons is enhanced by neuronal activity and is considered one of the mechanisms of neural circuit optimization. It is known that calcium signals affect transcriptional regulation and cytoskeletal remodeling necessary for dendritic outgrowth. Here we demonstrate that activity-dependent calcium signaling also controls mitochondrial homeostasis via AMP-activated protein kinase (AMPK) in growing dendrites of differentiating hippocampal neurons. We found that the inhibition of neuronal activity induces dendritic hypotrophy with abnormally elongated mitochondria. In growing dendrites, AMPK is activated by neuronal activity and dynamically oscillates in synchrony with calcium spikes, and this AMPK oscillation is inhibited by CaMKK2 knockdown. AMPK activation leads to phosphorylation of MFF and ULK1, which initiate mitochondrial fission and mitophagy, respectively. Dendritic mitochondria in AMPK-depleted neurons exhibit impaired fission and mitophagy and display multiple signs of dysfunction. Genetic inhibition of fission leads to dendritic hypoplasia reminiscent of AMPK deficient neurons. Thus, AMPK activity is finely tuned by the calcium-CaMKK2 pathway and regulates mitochondrial homeostasis by facilitating removal of damaged components of mitochondria in growing neurons during normal brain development.

Mulberry leaf flavonoids activate BAT and induce browning of WAT to improve type 2 diabetes via regulating the AMPK/SIRT1/PGC-1α signaling pathway

Mulberry (Morus alba L.) leaf is a well-established traditional Chinese botanical and culinary resource. It has found widespread application in the management of diabetes. The bioactive constituents of mulberry leaf, specifically mulberry leaf flavonoids (MLFs), exhibit pronounced potential in the amelioration of type 2 diabetes (T2D). This potential is attributed to their ability to safeguard pancreatic β cells, enhance insulin resistance, and inhibit α-glucosidase activity. Our antecedent research findings underscore the substantial therapeutic efficacy of MLFs in treating T2D. However, the precise mechanistic underpinnings of MLF’s anti-T2D effects remain the subject of inquiry. Activation of brown/beige adipocytes is a novel and promising strategy for T2D treatment. In the present study, our primary objective was to elucidate the impact of MLFs on adipose tissue browning in db/db mice and 3T3-L1 cells and elucidate its underlying mechanism. The results manifested that MLFs reduced body weight and food intake, alleviated hepatic steatosis, improved insulin sensitivity, and increased lipolysis and thermogenesis in db/db mice. Moreover, MLFs activated brown adipose tissue (BAT) and induced the browning of inguinal white adipose tissue (IWAT) and 3T3-L1 adipocytes by increasing the expressions of brown adipocyte marker genes and proteins such as uncoupling protein 1 (UCP1) and beige adipocyte marker genes such as transmembrane protein 26 (Tmem26), thereby promoting mitochondrial biogenesis. Mechanistically, MLFs facilitated the activation of BAT and the induction of WAT browning to ameliorate T2D primarily through the activation of AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor-gamma coactivator 1α (PGC-1α) signaling pathway. These findings highlight the unique capacity of MLF to counteract T2D by enhancing BAT activation and inducing browning of IWAT, thereby ameliorating glucose and lipid metabolism disorders. As such, MLFs emerge as a prospective and innovative browning agent for the treatment of T2D.

Purified Polysaccharides Extracted from Gray Oyster Mushroom (Pleurotus sajor-caju (Fr.) Sing.) Stimulate Glucose Uptake in C2C12 Myotubes through the activation of AMP-Activated Protein Kinase (AMPK) and Glucose Transporter 1 (GLUT1) Proteins

The grey oyster mushroom [Pleurotus sajor-caju (Fr.) Sing.], an edible mushroom, has been known as a source of bioactive compounds, including polysaccharides. Polysaccharides from this mushroom have been shown to possess antidiabetic activity both in vivo and in vitro. However, antidiabetic mechanism of partially purified or purified polysaccharides from the gray oyster mushroom has not been characterized. In this study, we extracted and purified polysaccharides from gray oyster mushrooms and used them to investigate the antidiabetic mechanism in the context of C2C12 myotubes. Using Fourier Transform Infrared spectroscopy (FTIR) analysis and enzymatic assay, we showed that the polysaccharide sample, namely 9S1-1, contains b-glucose, a-glucose, and mannose as the monosaccharide composition, and b-glucan is the major type of polysaccharide in the sample. This 9S1-1 sample dose-dependently stimulated glucose uptake in C2C12 myotubes. Further analysis showed that the sample activated the AMP-activated protein kinase (AMPK) but not Akt serine/threonine kinase (AKT) phosphorylation, suggesting that the stimulation is AMPK-dependent. Moreover, we showed that compound c, an inhibitor of AMPK, inhibited glucose uptake in 9S1-1-stimulated cells, confirming the requirement of AMPK in the glucose uptake activated by the 9S1-1 sample. In addition, it promoted glucose transporter protein type 1 (GLUT1) but not GLUT4 protein expression. These results suggest that GLUT1 may be responsible for the stimulation of glucose uptake in 9S1-1-activated cells. Together, these data illustrate the antidiabetic mechanism of polysaccharides isolated from the gray oyster mushroom and the potential use of the polysaccharide as an antidiabetic agent.

Feedback enhanced tumor targeting delivery of albumin-based nanomedicine to amplify photodynamic therapy by regulating AMPK signaling and inhibiting GSTs

Oxidative therapies receive a limited antitumor efficiency due to the insufficient reactive oxygen species (ROS) levels at focal sites and the evolvement of antioxidant defense systems. Herein, we develop an albumin-based nanomedicine to co-deliver chlorin e6 (Ce6) and COH-SR4 (CS), which can simultaneously enhance the yield and lethality of intracellular ROS for amplified photodynamic therapy (PDT). In which, CS acts as both an activator of AMP-activated protein kinase (AMPK) and an inhibitor of glutathione S-transferases (GSTs). Benefiting from it, the prepared HSA-Ce6@COH-SR4 (HCCS) enables positive feedback uptake by promoting AMPK phosphorylation, leading to rapid and extensive tumor accumulation of drugs. As a result, HCCS obviously increases the ROS production to elevate intracellular oxidative stress. Furthermore, HCCS can inhibit GSTs to disturb the antioxidant defense system of tumor cells, intensifying the oxidative damage of ROS. Ultimately, the PDT of HCCS is significantly strengthened by improving the ROS yield and lethality, which greatly declines the proliferation of breast cancer in vivo. This study may open a window in the development of drug co-delivery system for enhanced oxidative therapy of tumors.

Catalpol ameliorates LPS-induced inflammatory response by activating AMPK/mTOR signaling pathway in rat intestinal epithelial cells

Intestinal inflammation is a common clinical intestinal disease. Catalpol, a natural iridoid compound, has been shown to have anti-inflammatory, anti-oxidant and anti-apoptotic functions, but the mechanism of its protection against intestinal inflammation is still unclear. This study investigated the protective effect and potential mechanism of catalpol on the lipopolysaccharide (LPS)-induced inflammatory response of intestinal epithelial cell-6 (IEC-6). The results showed that catalpol could inhibit LPS-induced inflammatory response by dose-dependently reducing the release of inflammatory factors, such as tumor necrosis (TNF)-α, interleukin (IL)-1β and IL-6, and inhibiting the nuclear factor kappa-B (NF-κB) signaling pathway. Catalpol ameliorated cellular oxidative stress by reducing reactive oxygen species (ROS) and malondialdehyde (MDA) levels and increasing superoxide dismutase (SOD) and glutathione peroxidase (GSH-PX) expression. Meanwhile, catalpol also inhibited cell apoptosis, decreased the expression of B-cell lymphoma 2 (Bcl-2) - associated X (Bax), caspase 3 and caspase 9, and increased the expression of Bcl-2. This study found that catalpol activates AMP-activated protein kinase (AMPK) signaling pathway and inhibit mammalian target of rapamycin (mTOR) phosphorylationthe. In a further study, after inhibiting AMPK with dorsomorphin, the anti-inflammatory effects of catalpol were significantly reduced. Therefore, catalpol ameliorates LPS-induced inflammatory response by activating AMPK/mTOR signaling pathway in IEC-6 cells.

Glucose transporter 1 deficiency, AMP-activated protein kinase activation and immune dysregulation in autism spectrum disorder: Novel biomarker sources for clinical diagnosis

The neurophysiological basis of autism spectrum disorder (ASD) is still uncertain. Nevertheless, studies support the hypotheses that oxidative stress, neuroinflammation, immune dysregulation, and metabolic stress are contributors. In this study, the serum levels of 3-nitrotyrosine (3-NT), hypoxia-inducible factor 1 α (HIF-1 α), heat shock protein 70 (HSP-70), interleukin-17A (IL-17A), IL-35, vitamin D3 (VITD), glucose transporter-1 (GUT1), and AMP-activated protein kinase (AMPK) were estimated in Saudi ASD children versus age-matched neurotypical controls, aiming to investigate whether these parameters have potential roles in the pathophysiologic mechanisms of ASD and hoping to find a reliable marker for early ASD diagnosis. This study included 25 ASD children and 25 typically developing children (3–11 years old). The diagnosis of ASD cases was made based on the Autism Diagnostic Observation Schedule (ADOS) and the Statistical Manual of Mental Disorders (DSM-5). ASD subjects were commonly male and revealed an intelligence quotient (IQ) < 70.The results detected that ASD children have remarkable greater serum levels of nitrosative stress (3-NT), hypoxia (HIF-1 α), inflammatory (HSP-70, IL-17A, and AMPK) biomarkers and lower serum levels of anti-inflammatory (IL-35 and VITD) and metabolic stress (GUT-1) biomarkers versus age-matched controls (P ≤ 0.0001). Pearson's correlation study revealed that 3-NT was positively associated with HIF-1 α and HSP-70. HIF-1 α was also positively correlated with HSP-70. AMPK was positively associated with GUT-1, however, IL-17A was negatively correlated with IL-35 and VITD.Limitation:No specific therapeuticdrugs were administered in this study, and further studies are required to confirm the role of the selected biomarkers in ASD managements. ConclusionChanges in concentrations of different biomarkers indicate that they are involved in oxidative stress, metabolic stress, immune dysregulation and ASD pathogenesis. Hence, these parameters can prove to be promising biomarkers as well as therapeutic targets for the timely diagnosis and treatment of ASD patients.

AMPK Signaling Pathway as a Potential Therapeutic Target for Parkinson's Disease.

Parkinson's disease (PD) is the second most common neurodegenerative disease caused by the loss of dopaminergic neurons. Genetic factors, inflammatory responses, oxidative stress, metabolic disorders, cytotoxic factors, and mitochondrial dysfunction are all involved in neuronal death in neurodegenerative diseases. The risk of PD can be higher in aging individuals due to decreased mitochondrial function, energy metabolism, and AMP-activated protein kinase (AMPK) function. The potential of AMPK to regulate neurodegenerative disorders lies in its ability to enhance antioxidant capacity, reduce oxidative stress, improve mitochondrial function, decrease mitophagy and macroautophagy, and inhibit inflammation. In addition, it has been shown that modulating the catalytic activity of AMPK can protect the nervous system. This article reviews the mechanisms by which AMPK activation can modulate PD.

Berberine ameliorates collagen-induced arthritis in mice by restoring macrophage polarization via AMPK/mTORC1 pathway switching glycolytic reprogramming

Dysfunction of macrophage polarization majorly contributes to the progression of rheumatoid arthritis (RA). Polarization and functions of activated macrophages are closely associated with the reprogramming of intracellular metabolisms. Previously, we demonstrated that the anti-arthritis effect of berberine (BBR) in rats with adjuvant-induced arthritis (AA) may be related to AMP-activated protein kinase (AMPK) activation (a key regulator in the biological energy metabolism), and balanced macrophage polarization. However, the specific molecular mechanism of BBR in macrophage metabolism is yet to be elucidated. In this study, we clarified that BBR ameliorated articular inflammation and restored M1/M2 ratio in collagen-induced arthritis (CIA) mice in an AMPK-dependent manner. Mechanistically, BBR reversed the effects of mTORC1 agonist leucine (Leu) on regulating macrophage polarization through activation of AMPK to switch glycolytic reprogramming. Furthermore, BBR inhibition of mTORC1 rely on activation of AMPK to phosphorylate raptor and TSC2 instead of destroying its structure. Our study revealed that the activation of AMPK is required for the BBR-mediated anti-arthritis effect by downregulating mTORC1/HIF-1α and inhibiting the glycolysis in M1 macrophages.

In silico Prediction of Sodium-Glucose Co-Transporter-2 (SGLT2) Inhibition Activity by Allium Fistulosum Compound Based on SkelSpheres Molecular Descriptor

The Sodium-Glucose co-transporter-2 (SGLT2) inhibitor represents a novel agent for the treatment of type 2 diabetes. Drugs of this class function by inhibiting glucose reabsorption in the kidneys, thereby controlling blood glucose levels. It is known that SGLT2 inhibitors activate the AMPK signaling pathway by increasing the expression and activity of AMP-activated protein kinase (AMPK). In vivo tests have demonstrated that ethanolic and aqueous extracts of Welsh onion leaves (Allium fistulosum L) can reduce body weight, liver weight, adipocyte size, and enhance AMP-activated protein kinase (AMPK) expression. In this study, the inhibitory activity (IC50) of compounds within Allium fistulosum against SGLT2 was predicted using the Support Vector Regression (SVR) predictive model and the SkelSpheres descriptor. The results of the predicted IC50 measurements for compounds present in the 70% ethanol extract of Allium fistulosum in silico indicate that 4 tyramine derivatives and 1 decursidate compound exhibit Excellent or Potent inhibitor activity criteria (IC50 &lt; 1 µM). Among these, the four tyramine group compounds are the isomers N-trans-feruloyltyramine and N-cis-feruloyltyramine, as well as the isomers N-trans-feruloyl-3'-methoxytyramine and N-cis-feruloyl-3'-methoxytyramine. The findings of this study suggest that the ability of Allium fistulosum to enhance AMPK expression is possibly achieved through the inhibition of SGLT2.

Soluble epoxide hydrolase-targeting PROTAC activates AMPK and inhibits endoplasmic reticulum stress

Soluble epoxide hydrolase (sEH) is a drug target with the potential for therapeutic utility in the areas of inflammation, neurodegenerative disease, chronic pain, and diabetes, among others. Proteolysis-targeting chimeras (PROTACs) molecules offer new opportunities for targeting sEH, due to its capacity to induce its degradation. Here, we describe that the new ALT-PG2, a PROTAC that degrades sEH protein in the human hepatic Huh-7 cell line, in isolated mouse primary hepatocytes, and in the liver of mice. Remarkably, sEH degradation caused by ALT-PG2 was accompanied by an increase in the phosphorylated levels of AMP-activated protein kinase (AMPK), while phosphorylated extracellular-signal-regulated kinase 1/2 (ERK1/2) was reduced. Consistent with the key role of these kinases on endoplasmic reticulum (ER) stress, ALT-PG2 attenuated the levels of ER stress and inflammatory markers. Overall, the findings of this study indicate that targeting sEH with degraders is a promising pharmacological strategy to promote AMPK activation and to reduce ER stress and inflammation.

Glucose restriction induces AMPK-SIRT1-mediated circadian clock gene Per expression and delays NSCLC progression

The rhythmic expression of the circadian clock is intimately linked to the health status of the body. Disturbed circadian clock rhythms might lead to a wide range of metabolic diseases and even cancers. Our previous study showed that glucose restriction was able to inhibit non-small cell lung cancer (NSCLC). In the current study, we found that glucose restriction enhanced apoptosis and cell growth delay in NSCLC cells. In addition, we used GEPIA database analysis to derive different effects of each circadian clock gene on lung cancer tissue. Among these circadian clock genes, Per (Period) is lowly expressed in cancer tissues and highly expressed in normal tissues. Moreover, the higher expression of Per in cancer patients has a better prognostic significance. Furthermore, we revealed that glucose restriction induced the expression of the circadian clock gene Per in NSCLC cells by upregulating SIRT1 (Sirtuin1) via activation of the energy response factor AMPK (AMP-activated protein kinase). Changes in Per expression following upregulation or downregulation of AMPK were consistent with AMPK expression. Additionally, a low-carbohydrate ketogenic diet significantly delayed tumor progression in a xenograft tumor model of severe combined immunodeficiency (SCID) mice. Meanwhile, the ketogenic diet increased the expression of AMPK, SIRT1 and Per in vivo. Besides, the ketogenic diet was found to restore the normal rhythmic level of Per by Zeitgeber Time (ZT) experiments. Taken these together, these results indicated a novel mechanism that glucose restriction induces AMPK-SIRT1 mediated circadian clock gene Per expression and delays NSCLC progression, which provided more evidence for glucose restriction as an adjuvant clinical therapeutic strategy in NSCLC.