AMP-activated Protein Kinase Activation Research Articles

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.

Sex differences in obesity-induced renal lipid accumulation revealed by lipidomics: a role of adiponectin/AMPK axis

BackgroundSex differences have been observed in the development of obesity-related complications in patients, as well as in animal models. Accumulating evidence suggests that sex-dependent regulation of lipid metabolism contributes to sex-specific physiopathology. Lipid accumulation in the renal tissue has been shown to play a major role in the pathogenesis of obesity-induced kidney injury. Unlike in males, the physiopathology of the disease has been poorly described in females, particularly regarding the lipid metabolism adaptation.MethodsHere, we compared the lipid profile changes in the kidneys of female and male mice fed a high-fat diet (HFD) or low-fat diet (LFD) by lipidomics and correlated them with pathophysiological changes.ResultsWe showed that HFD-fed female mice were protected from insulin resistance and hepatic steatosis compared to males, despite similar body weight gains. Females were particularly protected from renal dysfunction, oxidative stress, and tubular lipid accumulation. Both HFD-fed male and female mice presented dyslipidemia, but lipidomic analysis highlighted differential renal lipid profiles. While both sexes presented similar neutral lipid accumulation with obesity, only males showed increased levels of ceramides and phospholipids. Remarkably, protection against renal lipotoxicity in females was associated with enhanced renal adiponectin and AMP-activated protein kinase (AMPK) signaling. Circulating adiponectin and its renal receptor levels were significantly lower in obese males, but were maintained in females. This observation correlated with the maintained basal AMPK activity in obese female mice compared to males.ConclusionsCollectively, our findings suggest that female mice are protected from obesity-induced renal dysfunction and lipotoxicity associated with enhanced adiponectin and AMPK signaling compared to males.

Pharmacological Effects of Botanical Drugs on Myocardial Metabolism in Chronic Heart Failure.

Although there have been significant advances in the treatment of heart failure in recent years, chronic heart failure remains a leading cause of cardiovascular disease-related death. Many studies have found that targeted cardiac metabolic remodeling has good potential for the treatment of heart failure. However, most of the drugs that increase cardiac energy are still in the theoretical or testing stage. Some research has found that botanical drugs not only increase myocardial energy metabolism through multiple targets but also have the potential to restore the balance of myocardial substrate metabolism. In this review, we summarized the mechanisms by which botanical drugs (the active ingredients/formulas/Chinese patent medicines) improve substrate utilization and promote myocardial energy metabolism by activating AMP-activated protein kinase (AMPK), peroxisome proliferator-activated receptors (PPARs) and other related targets. At the same time, some potential protective effects of botanical drugs on myocardium, such as alleviating oxidative stress and dysbiosis signaling, caused by metabolic disorders, were briefly discussed.

Betaine Intervention as a Novel Approach to Preventing Doxorubicin-Induced Cardiotoxicity

The anthracycline anticancer drug doxorubicin (Dox) is widely prescribed for treating lung, ovary, breast, lymphoma, sarcoma, and pediatric cancer. Mechanistically, Dox intercalates the DNA and inhibits the topoisomerase II enzyme in fast-proliferating cancer. The clinical application of Dox is limited due to its cardiotoxicity, including congestive heart failure, alterations in myocardial structure, arrhythmia, and left ventricular dysfunction. Dox causes cardiotoxicity via various mechanisms, including oxidative stress, mitochondrial dysfunctioning, deranged Ca2+ homeostasis, inflammation, fibrosis, downregulating AMPK, etc. Betaine is a zwitterion-based drug known as N, N, N trimethylglycine that regulates the methionine cycle and homocysteine (a risk factor for cardiovascular disease) detoxification through betaine-homocysteine methyltransferases. Betaine is nontoxic and has several beneficial effects in different disease models. Betaine treatment decreases the amyloid β generation, reduces obesity, improves steatosis and fibrosis, and activates AMP-activated protein kinase (AMPK). Further, betaine downregulates 8‑hydroxy-2-deoxyguanosine, malondialdehyde, and upregulates catalases, glutathione peroxidase, and superoxide dismutase activity. Therefore, we hypothesized that betaine might be a rational drug candidate to effectively combat Dox-associated oxidative stress, inflammation, and mitochondrial dysfunction.

Dexamethasone-induced mitochondrial ROS-mediated inhibition of AMPK activity facilitates osteoblast necroptosis.

Long-term or high-dose glucocorticoid use can lead to serious orthopedic complications, including femoral head necrosis. Both basic and clinical studies have shown that high doses dexamethasone (Dex) can directly induce osteoblasts death. This study investigated the mechanism underlying Dex induced osteoblast death. In this study, we showed that Dex induces osteoblast necroptosis, rather than apoptosis, through the inhibition of AMP-activated protein kinase (AMPK) activity. We also demonstrated that inactivation of AMPK-mediated necroptosis is through receptor-interacting protein kinase 3 (RIP3), but not RIP1. Furthermore, we found that Dex-induced necroptosis is dependent on mitochondrial reactive oxygen species (ROS) following with directly activation of RIP1 and inactivation of AMPK. These findings provide new insights into the mechanism of Dex-induced osteoblast death and may have implications for the development of new therapies for osteoporosis and other bone-related diseases.

Modulation of cardiac cAMP signaling by AMPK and its adjustments in pressure overload-induced myocardial dysfunction in rat and mouse.

The beta-adrenergic system is a potent stimulus for enhancing cardiac output that may become deleterious when energy metabolism is compromised as in heart failure. We thus examined whether the AMP-activated protein kinase (AMPK) that is activated in response to energy depletion may control the beta-adrenergic pathway. We studied the cardiac response to beta-adrenergic stimulation of AMPKα2-/- mice or to pharmacological AMPK activation on contractile function, calcium current, cAMP content and expression of adenylyl cyclase 5 (AC5), a rate limiting step of the beta-adrenergic pathway. In AMPKα2-/- mice the expression of AC5 (+50%), the dose response curve of left ventricular developed pressure to isoprenaline (p<0.001) or the response to forskolin, an activator of AC (+25%), were significantly increased compared to WT heart. Similarly, the response of L-type calcium current to 3-isobutyl-l-methylxanthine (IBMX), a phosphodiesterase inhibitor was significantly higher in KO (+98%, p<0.01) than WT (+57%) isolated cardiomyocytes. Conversely, pharmacological activation of AMPK by 5-aminoimidazole-4-carboxamide riboside (AICAR) induced a 45% decrease in AC5 expression (p<0.001) and a 40% decrease of cAMP content (P<0.001) as measured by fluorescence resonance energy transfer (FRET) compared to unstimulated rat cardiomyocytes. Finally, in experimental pressure overload-induced cardiac dysfunction, AMPK activation was associated with a decreased expression of AC5 that was blunted in AMPKα2-/- mice. The results show that AMPK activation down-regulates AC5 expression and blunts the beta-adrenergic cascade. This crosstalk between AMPK and beta-adrenergic pathways may participate in a compensatory energy sparing mechanism in dysfunctional myocardium.

High levels of uric acid inhibit BAT thermogenic capacity through regulation of AMPK.

Hyperuricemia (HUA) is strongly associated with the increasing prevalence of obesity, but the underlying mechanism remains elusive. Dysfunction of brown adipose tissue (BAT) could lead to obesity. However, studies on the role of HUA on BAT are lacking. Our retrospective clinical analysis showed that serum uric acid (UA) is significantly associated with BAT in humans. To investigate the role of UA in regulating BAT function, we used UA to treat primary brown adipocytes (BACs) in vitro and established HUA mice. In vitro results showed that HUA suppressed thermogenic gene expression and oxygen consumption rate. Accordingly, HUA mice exhibited lower energy expenditure and body temperature, with larger lipid droplets and lower thermogenic gene expression. These results demonstrate that HUA inhibits BAT thermogenic capacity in vitro and in vivo. To further elucidate the mechanism of UA on adipocytes, mRNA-sequencing analysis was performed and screened for "AMP-activated protein kinase (AMPK) signaling pathway" and "mitochondrial biogenesis." Further tests in vivo and in vitro showed that the phosphorylation of AMPK was suppressed by HUA. Activation of AMPK alleviated the inhibition of AMPK phosphorylation by HUA and increased mitochondrial biogenesis, subsequently restoring the impaired BAT thermogenic capacity in vitro and vivo. Thus, we confirmed that HUA suppresses mitochondrial biogenesis by regulating AMPK, thereby inhibiting BAT thermogenic capacity. Taken together, our study identifies UA as a novel regulator of BAT thermogenic capacity, providing a new strategy to combat obesity.NEW & NOTEWORTHY To investigate the effect and mechanism of UA on BAT thermogenic capacity, we established HUA models in vitro and in vivo, and performed RNA sequencing analysis. Our results revealed that HUA suppresses mitochondrial biogenesis by regulating AMPK, thereby inhibiting BAT thermogenic capacity. Taken together, our study identifies UA as a novel regulator of BAT thermogenic capacity, providing a new strategy to combat obesity.

Accumulation of Prion Triggers the Enhanced Glycolysis via Activation of AMKP Pathway in Prion-Infected Rodent and Cell Models.

Mitochondrial dysfunction is one of the hallmarks in the pathophysiology of prion disease and other neurodegenerative diseases. Various metabolic dysfunctions are identified and considered to contribute to the progression of some types of neurodegenerative diseases. In this study, we evaluated the status of glycolysis pathway in prion-infected rodent and cell models. The levels of the key enzymes, hexokinase (HK), phosphofructokinase (PFK), and pyruvate kinase (PK) were significantly increased, accompanying with markedly downregulated mitochondrial complexes. Double-stained IFAs revealed that the increased HK2 and PFK distributed widely in GFAP-, Iba1-, and NeuN-positive cells. We also identified increased levels of AMP-activated protein kinase (AMPK) and the downstream signaling. Changes of AMPK activity in prion-infected cells by the AMPK-specific inhibitor or activator induced the corresponding alterations not only in the downstream signaling, but also the expressions of three key kinases in glycolysis pathway and the mitochondrial complexes. Transient removal or complete clearance of prion propagation in the prion-infected cells partially but significantly reversed the increases of the key enzymes in glycolysis, the upregulation of AMPK signaling pathway, and the decreases of the mitochondrial complexes. Measurements of the cellular oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) showed lower OCR and higher ECAR in prion-infected cell line, which were sufficiently reversed by clearance of prion propagation. Those data indicate a metabolic reprogramming from oxidative phosphorylation to glycolysis in the brains during the progression of prion disease. Accumulation of PrPSc is critical for the switch to glycolysis, largely via activating AMPK pathway.

FSHR-mTOR-HIF1 signaling alleviates mouse follicles from AMPK-induced atresia

The majority of activated ovarian follicles undergo atresia during reproductive life in mammals, and only a small number of follicles are ovulated. Though hormone treatment has been widely used to promote folliculogenesis, the molecular mechanism behind follicle selection and atresia remains under debate due to inconsistency among investigation models. Using a high-throughput molecular pathology strategy, we depicted a transcriptional atlas of mouse follicular granulosa cells (GCs) under physiological condition and obtained molecular signatures in healthy and atresia GCs during development. Functional results revealed hypoxia-inducible factor 1 (HIF1) as a major effector downstream of follicle-stimulating hormone (FSH), and HIF1 activation is essential for follicle growth. Energy shortage leads to prevalent AMP-activated protein kinase (AMPK) activation and drives follicular atresia. FSHR-mTOR-HIF1 signaling helps follicles escape from the atresia fate, while energy stress persists. Our work provides a comprehensive understanding of the molecular network behind follicle selection and atresia under physiological condition.

AMPK protects endothelial cells against HSV-1 replication via inhibition of mTORC1 and ACC1.

Herpes simplex virus type 1 (HSV-1) is a widespread contagious pathogen, mostly causing mild symptoms on the mucosal entry side. However, systemic distribution, in particular upon reactivation of the virus in immunocompromised patients, may trigger an innate immune response and induce damage of organs. In these conditions, HSV-1 may infect vascular endothelial cells, but little is known about the regulation of HSV-1 replication and possible defense mechanisms in these cells. The current study addresses the question of whether the host cell protein AMP-activated protein kinase (AMPK), an important metabolic sensor, can control HSV-1 replication in endothelial cells. We show that downregulation of the catalytic subunits AMPKα1 and/or AMPKα2 increased HSV-1 replication as monitored by TCID50 titrations, while a potent AMPK agonist, MK-8722, strongly inhibited it. MK-8722 induced a persistent phosphorylation of the AMPK downstream targets acetyl-CoA carboxylase (ACC) and the rapamycin-sensitive adaptor protein of mTOR (Raptor) and, related to this, impairment of ACC1-mediated lipid synthesis and the mechanistic target of the rapamycin complex-1 (mTORC1) pathway. Since blockade of mTOR by Torin-2 as well as downregulation of ACC1 by siRNA also decreased HSV-1 replication, MK-8722 is likely to exert its anti-viral effect via mTORC1 and ACC1 inhibition. Importantly, MK-8722 was able to reduce virus replication even when added after HSV-1. Together, our data highlight the importance of endothelial cells as host cells for HSV-1 replication upon systemic infection and identify AMPK, a metabolic host cell protein, as a potential target for antiviral strategies against HSV-1 infection and its severe consequences. IMPORTANCE Herpes simplex virus type 1 (HSV-1) is a common pathogen that causes blisters or cold sores in humans. It remains latent in infected individuals and can be reactivated multiple times. In adverse conditions, for instance, in immunocompromised patients, HSV-1 can lead to serious complications such as encephalitis, meningitis, or blindness. In these situations, infection of endothelial cells lining the surface of blood vessels may contribute to the manifestation of disease. Here, we describe the role of AMP-activated protein kinase (AMPK), a potent regulator of cellular energy metabolism, in HSV-1 replication in endothelial cells. While downregulation of AMPK potentiates HSV-1 replication, pharmacological AMPK activation inhibits it by limiting the availability of required host cell macromolecules such as proteins or fatty acids. These data highlight the role of metabolic host cell proteins as antiviral targets and reveal activation of endothelial AMPK as a potential strategy to protect from severe consequences of HSV-1 infection.

Cheong-sang-bang-pung-san alleviated hepatic lipid accumulation by regulating lipid metabolism in vitro and in vivo.

Introduction: The occurrence of fatty liver disease, resulting from the accumulation of excessive fat within the liver, has been showing a significant and rapid increase. This study aimed to evaluate the therapeutic effects of Cheong-sang-bang-pung-san extract (CB) on fatty liver disease, and to elucidate the underlying mechanisms. Methods: We used a high-fat diet (HFD)-fed fatty liver mice and free fatty acid (FFA) induced HepG2 cell lipid accumulation model. The levels of serum, hepatic, and intracellular lipid content were assessed. Histopathological staining was used to evaluate the extent of hepatic lipid accumulation. Real-time polymerase chain reaction and Western blotting were conducted to examine the expression of factors associated with lipid metabolism. Results: We demonstrated that treatment with CB dramatically reduced body weight, liver weight, and fat mass, and improved the serum and hepatic lipid profiles in HFD-induced fatty liver mice. Additionally, CB alleviated lipid accumulation in HFD-fed mice by controlling lipid metabolism, including fatty acid uptake, triglyceride and cholesterol synthesis, and fatty acid oxidation, at the mRNA as well as protein levels. In free fatty acid-treated HepG2 cells, CB significantly reduced intracellular lipid accumulation by regulating lipid metabolism via the activation of AMP-activated protein kinase. Conclusion: These findings provide insights into the mechanisms underlying CB's effects on liver steatosis and position of CB as a potential therapeutic candidate for managing lipid metabolic disorders.