Adenosine Monophosphate-activated Protein Kinase Activation Research Articles

Delphinidin induces a fast-to-slow muscle fiber type shift through the AMPK signaling pathway in C2C12 myotubes

Delphinidin, a plant anthocyanidin, suppresses disuse muscle atrophy in mice. However, its effect on muscle fiber type shift is unclear. To examine whether delphinidin affects skeletal muscle fiber type, differentiated C2C12 cells were treated with delphinidin. Results revealed that delphinidin upregulated the mRNA expression of myosin heavy chain type I (MyHCI), troponin C1, troponin I1, and MyHCIIx and increased slow MyHC protein level in C2C12 myotubes. Delphinidin also enhanced succinic dehydrogenase (SDH) activities and suppressed lactate dehydrogenase (LDH) activity. Adenosine monophosphate–activated protein kinase (AMPK) inhibition attenuated delphinidin-induced MyHCI upregulation and MyHCIIb downregulation. We investigated the effect of delphinidin on the upstream factors involved in AMPK activation. Delphinidin increased liver kinase B1 (LKB1) phosphorylation and nuclear respiratory factor 1 (NRF1) and calcium/calmodulin-dependent protein kinase 2 (CaMKK2) protein levels. In conclusion, delphinidin induced muscle fiber type conversion from fast-twitch to slow-twitch muscles through the AMPK signaling pathway.

Coptisine inhibits lipid accumulation in high glucose- and palmitic acid-induced HK-2 cells by regulating the AMPK/ACC/CPT-1 signaling pathway.

AMPK (Adenosine 5'-Monophosphate activated Protein Kinase) functions as a fundamental regulator of glycolipid metabolism by regulating the rate-limiting enzyme activity of ACC (Acetyl-CoA Carboxylase, essential for fatty acid biosynthesis) and CPT-1 (Carnitine palmitoyltransferase-1, essential for mitochondrial fatty acid oxidation, FAO) in cells, which is crucial for maintaining energy homeostasis in the human body. Coptisine (COP) is a natural berberine and isoquinoline alkaloid in Coptis chinensis that has been used as a traditional Chinese herb to treat diabetes for thousands of years, but its mechanism of action is still unclear. In this study, we investigated the anti-lipid accumulation effect and mechanism of COP in high glucose and palmitic acid-induced HK-2 cells. Compared with the control HK-2 cells, the model HK-2 cells exhibited markedly greater lipid deposition, after treatment with high glucose (HG, 30 mM) and palmitic acid (PA, 250 µM) for 24h. However, COP significantly decreased the TC and TG levels in a dose dependent manner (2.5, 5, and 10 µM). Moreover, COP dramatically enhanced the effect of the positive control (AICAR, Acadesine, an AMPK activator) in alleviating lipid deposition, which was reversed by the negative control (Compound C, an AMPK inhibitor). Furthermore, COP also increased p-AMPK, p-ACC and CPT-1 protein expression. Our results indicate that COP can effectively protects HK-2 cells against HG- and PA-induced lipid accumulation by affecting the AMPK/ACC/CPT-1 signaling pathway, inhibiting de novo lipogenesis and enhancing the FAO processes, which offers novel insights for the application of COP in the clinic.

L-aspartate ameliorates diet-induced obesity by increasing adipocyte energy expenditure.

Obesity always leads to profound perturbation of metabolome. Metabolome studies enrich the knowledge on associations between endogenous metabolites and obesity, potentially providing innovative strategies for the development of novel anti-obesity pharmacotherapy. This study aims to identify an endogenous metabolite that regulates energy expenditure and to explore its application for obesity treatment. C57BL/6 mice were fed with a high-fat and high-cholesterol (HFC) diet, comprising 60% fat and 1.2% cholesterol, for 12 weeks to induce obesity. Significant metabolites were identified in the livers of both health and obese mice through comparative hepatic metabolomics analysis. Correlation between serum or adipose L-aspartate level and body weight in obese mice, as well as human body mass index (BMI), was evaluated. In addition, saline or 200 mg/kg L-aspartate was orally administrated to HFC diet mice and HFC diet-induced obese mice for 6-7 weeks. Body weight, adipose tissue weight, glucose tolerance and liver damage were assessed to evaluate the effect on obesity prevention and treatment. Comprehensive lab animal monitoring system (CLAMS) and seahorse assay were employed to investigate the regulatory effect of L-aspartate on energy metabolism in vivo and in vitro, respectively. 3T3-L1 preadipocytes and murine white adipose tissue (WAT) were utilized to examine the impact of L-aspartate on adipocyte adipogenesis and lipogenesis and cellular signalling pathway in vitro and in vivo. L-aspartate, an approved drug for liver injury and chronic fatigue, was identified as an endogenous inducer of energy expenditure. Serum or adipose L-aspartate levels were found to be negatively correlated with the severity of obesity in both humans and mice. Administration of L-aspartate to HFC diet mice led to a significant reduction in body weight, with decreases of 14.5% in HFC diet mice and 8.5% in HFC diet-induced obese mice, respectively. In addition, the treatment improved related metabolic syndrome (Figure 2 and Figure S3). These therapeutics were associated with enhancements in whole-body energy expenditure and suppression of adipocyte adipogenesis along with activation of Adenosine 5'-monophosphate-activated protein kinase (AMPK) signalling pathway. L-aspartate may serve as a novel endogenous inducer of energy expenditure and suppressor of adipogenesis and lipogenesis along with activation of AMPK, thereby offering a promising therapeutic strategy for obesity prevention and treatment.

Exercise training attenuates cardiac dysfunction induced by excessive sympathetic activation through an AMPK-KLF4-FMO2 axis

Cardiovascular diseases (CVDs) are a leading cause of mortality worldwide and are associated with an overactivated sympathetic system. Although exercise training has shown promise in mitigating sympathetic stress-induced cardiac remodeling, the precise mechanisms remain elusive. Here, we demonstrate that exercise significantly upregulates cardiac flavin-containing monooxygenase 2 (FMO2) expression. Notably, we find that exercise training effectively counteracts sympathetic overactivation-induced cardiac dysfunction and fibrosis by enhancing FMO2 expression via adenosine 5′-monophosphate (AMP)-activated protein kinase (AMPK) activation. Functional investigations employing FMO2 knockdown with adeno-associated virus 9 (AAV9) underscore the necessity for FMO2 expression to protect the heart during exercise in vivo. Furthermore, we identify the krüppel-like factor 4 (KLF4) as a transcriptional mediator of FMO2 that is crucial for the mechanism through which AMPK activation protects against sympathetic overactivation-induced cardiac dysfunction and fibrosis. Taken together, our study reveals a cardioprotective mechanism for exercise training through an AMPK-KLF4-FMO2 signaling pathway that underscores how exercise alleviates cardiac dysfunction induced by excessive sympathetic activation.

ULK1-regulated AMP sensing by AMPK and its application for the treatment of chronic kidney disease

Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a central kinase involved in energy homeostasis. Increased intracellular AMP levels result in AMPK activation through the binding of AMP to the γ-subunit of AMPK. Recently, we reported that AMP-induced AMPK activation is impaired in the kidneys in chronic kidney disease (CKD) despite an increase in the AMP/ATP ratio. However, the mechanisms by which AMP sensing is disrupted in CKD are unclear. Here, we identified mechanisms of energy homeostasis in which Unc-51-like kinase 1 (ULK1)-dependent phosphorylation of AMPKγ1 at Ser260/Thr262 promoting AMP sensitivity of AMPK. AMPK activation by AMP was impaired in Ulk1 knockout mice despite an increased AMP/ATP ratio. ULK1 expression is markedly downregulated in CKD kidneys, leading to AMP sensing failure. Additionally, MK8722, an allosteric AMPK activator, stimulated AMPK in the kidneys of a CKD mouse model (5/6th nephrectomy) via a pathway that is independent of AMP sensing. Thus, our study shows that MK8722 treatment significantly attenuates the deterioration of kidney function in CKD and may be a potential therapeutic option in CKD therapeutics.

Suppression of hepatic steatosis in non-alcoholic steatohepatitis model by modified Xiaoyao San formula: Evidence, mechanisms and perspective.

In this letter, we comment on a recent publication by Mei et al, in the World Journal of Hepatology, investigating the hepatoprotective effects of the modified Xiaoyao San (MXS) formula in a male rat model of non-alcoholic steatohepatitis (NASH). The authors found that MXS treatment mitigated hepatic steatosis and inflammation in the NASH model, as evidenced by the reduction in lipid droplets (LDs), fibrosis markers and lipogenic factors. Interestingly, these hepatoprotective effects were associated with androgen upregulation (based on metabolomics analysis of male steroid hormone metabolites), adenosine 5'-monophosphate-activated protein kinase (AMPK) activation, and restoration of phosphatase and tensin homolog (PTEN) expression. However, the authors did not clearly discuss the relationships between MXS-induced hepatic steatosis reduction in the NASH model, and androgen upregulation, AMPK activation, and restoration of PTEN expression. This editorial emphasizes the reported mechanisms and explains how they act or interact with each other to reduce hepatic steatosis and inflammation in the NASH model. As a perspective, we propose additional mechanisms (such as autophagy/lipophagy activation in hepatocytes) for the clearance of LDs and suppression of hepatic steatosis by MXS in the NASH model. A proper understanding of the mechanisms of MXS-induced reduction of hepatic steatosis might help in the treatment of NASH and related diseases.

Regulation of Bacillus Calmette-Guérin-induced macrophage autophagy and apoptosis by the AMPK–mTOR–ULK1 pathway

Tuberculosis (TB) is a chronic wasting infectious disease caused by Mycobacterium tuberculosis (MTB) or Mycobacterium bovis that can be transmitted among people and domestic animals. During the development of TB, macrophages of the innate immune system can act against MTB via autophagy and apoptosis to prevent the spread of the disease. Among the many autophagy regulatory pathways, the adenosine monophosphate (AMP)–activated protein kinase (AMPK)–mammalian rapamycin target protein (mTOR)–Unc-51-like kinase 1 (ULK1) pathway has received considerable attention. This study investigates the regulatory role of the AMPK–mTOR–ULK1 pathway in attenuating M. bovis Bacillus Calmette–Guérin (BCG)-induced autophagy and apoptosis in murine monocyte macrophages (RAW264.7). Changes in macrophage autophagy and apoptosis were analyzed using the AMPK activator AICAR and inhibitor Compound C to interfere with the AMPK–mTOR–ULK1 pathway and siRNA to silence the pathway. Consequently, BCG stimulation of macrophages significantly activated the AMPK–mTOR–ULK1 pathway while BCG-induced macrophage AMPK activation promoted macrophage autophagy and apoptosis. Activation of the AMPK–mTOR–ULK1 pathway by AICAR significantly improved autophagy occurrence in BCG-induced macrophages and increased apoptosis while Compound C with siRNA produced opposing effects by attenuating autophagy and apoptosis in BCG-induced macrophages. Thus, the AMPK–mTOR–ULK1 pathway has a dual regulatory role in BCG-induced macrophage autophagy and apoptosis and may have synergistic effects. This study analyzes the mechanism of resistance of host cells to MTB and provides a theoretical basis for new therapeutic strategies and related drug development.

Does Concomitant Use of Methotrexate with JAK Inhibition Confer Benefit for Cardiovascular Outcomes? A Commentary.

This commentary explores the potential cardiovascular (CV) benefits of combining methotrexate (MTX) and Janus kinase inhibitors (JAKis) in the treatment of rheumatoid arthritis (RA). While European guidelines recommend MTX as first-line treatment, concerns about the CV risks associated with JAKis have emerged. This article reviews the existing literature to assess the role of concomitant MTX in reducing CV risk when used with JAKis. Clinical trials confirm the efficacy of JAKis in combination with MTX in terms of treatment outcomes in RA. However, the number of major adverse cardiovascular events (MACEs) reported is too low to draw conclusions on adverse CV outcomes. Indirect evidence does, however, suggest potential protective effects of MTX on CV outcomes, as several mechanisms may contribute to MTX's cardioprotective effects, including reduced inflammation, adenosine monophosphate-activated protein kinase (AMPK) activation, increased cholesterol efflux, and adenosine accumulation. These mechanisms and the available data may support the case for CV benefits of concomitant MTX when JAKis are used in the treatment of patients with RA, although further research is needed. In particular, the lipid paradox associated with RA highlights the complex relationship between RA treatments (MTX, JAKis, tumor necrosis factor (TNF) inhibitors, and interleukin (IL)-6 receptor inhibitors), inflammation, different lipid profiles, and CV risk. In the absence of contraindications and when MTX is tolerated, this commentary suggests the concomitant use of MTX and JAKis as a preferred option for optimizing CV protection in patients with RA.

Unveiling the impacts of metformin on hepatocellular carcinoma: A bioinformatic exploration in cell lines

The most common type of liver cancer is hepatocellular carcinoma (HCC), accounting for 75–85% of cases. Despite its associated side effects, sorafenib remains the standard treatment for HCC. Given the critical need to improve therapeutic efficacy while minimizing adverse effects, alternative drugs must be thoroughly investigated. Numerous studies indicate that combining sorafenib with metformin results in a more favorable treatment profile. The aim of this study was to employ bioinformatics methodologies to elucidate the molecular pathways and genetic underpinnings of metformin's efficacy in HCC treatment. Genes associated with metformin and its action against HCC (Huh-7 and HepG2 cells) were acquired from the NCBI-GEO data collection by utilizing pre-determined keywords. Subsequently, pathways implicated in metformin-mediated HCC treatment were analyzed through the Kyoto Encyclopedia of Genes and Genomes (KEGG). Our analysis revealed the involvement of multiple pathways, with metabolic pathways implicated in 80% of the total cases. Neurodegenerative pathways were involved in only around 60% of the total cases. These findings align with the multifaceted mechanisms of metformin’s action, encompassing adenosine monophosphate-activated protein kinase activation, apoptosis induction, insulin regulation, anti-inflammatory responses, and modulation of cell proliferation. This comprehensive investigation sheds light on the intricate molecular landscape underpinning metformin's therapeutic efficacy in HCC, thereby informing potential avenues for optimizing treatment strategies.

Lung-Targeting Perylenediimide Nanocomposites for Efficient Therapy of Idiopathic Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis, an idiopathic interstitial lung disease with high mortality, remains challenging to treat due to the lack of clinically approved lung-targeting drugs. Herein, we present PDIC-DPC, a perylenediimide derivative that exhibits superior lung-selective enrichment. PDIC-DPC forms nanocomposites with plasma proteins, including fibrinogen beta chain and vitronectin, which bind to pulmonary endothelial receptors for lung-specific accumulation. Moreover, PDIC-DPC significantly suppresses transforming growth factor beta1 and activates adenosine monophosphate-activated protein kinase. As a result, compared to existing therapeutic drugs, PDIC-DPC achieves superior therapeutic outcomes, evidenced by the lowest Ashcroft score, significantly improved pulmonary function, and an extended survival rate in a bleomycin-induced pulmonary fibrosis model. This study elucidates the lung-selective enrichment of assembled prodrug from biological perspectives and affords a platform enabling therapeutic efficiency on idiopathic pulmonary fibrosis.

Structure-activity relationships study of N-ethylene glycol-comprising alkyl heterocyclic carboxamides against A549 lung cancer cells.

Aim: Certain cancer cells depend on oxidative phosphorylation for survival; thus, inhibiting this process may be a promising treatment strategy. This study explored the structure-activity relationships of the mitochondrial inhibitor N-ethylene glycol-comprising alkyl thiophene-3-carboxamide 3.Methods & results: We synthesized and evaluated 13 analogs (5a-m) with different ethylene glycol units, heterocyclesand connecting groups for their growth-inhibitory effects on A549 non-small cell lung cancer cells. We found that increasing the number of ethylene glycol units significantly enhanced inhibitory activity. Some analogs activated adenosine monophosphate-activated protein kinase, similar to 3. Notably, analog 5e, which contains tetraethylene glycol units, significantly inhibited tumor growth in vivo.Conclusion: Analog 5 may be a potential therapeutic agent for non-small cell lung cancer treatment.

Artemisinin conferred cytoprotection to human retinal pigment epithelial cells exposed to amiodarone-induced oxidative insult by activating the CaMKK2/AMPK/Nrf2 pathway

BackgroundOcular toxicity is a severe adverse effect that limits the chronic clinical use of the antiarrhythmic drug amiodarone. Here, we aimed to evaluate the cytoprotective effect of artemisinin and explore the potential signalling pathways in human retinal pigment epithelial (RPE) cell cultures.MethodsD407 cell cultures were exposed to amiodarone and the impact of artemisinin was evaluated. The key parameters included lactate dehydrogenase (LDH) release, intracellular reactive oxygen species (ROS) generation, and the mitochondrial membrane potential (MMP). We also assessed the protein levels of cleaved caspase-3, cleaved poly (ADP-ribose) polymerase (PARP), phosphorylated adenosine monophosphate-activated protein kinase (AMPK)ɑ (p-AMPK), calcium/calmodulin-dependent protein kinase kinase 2 (CaMKK2), and nuclear factor erythroid 2-related factor 2 (Nrf2).ResultsArtemisinin reduced the cytotoxicity induced by amiodarone, as reflected by decreased LDH release, ROS generation, and MMP disruption. Additionally, artemisinin increased p-AMPK, CaMKK2, and Nrf2 protein levels. Inhibition of AMPK, CaMKK2, or Nrf2 abolished the cytoprotective effect of artemisinin. AMPK activation and Nrf2 knockdown further supported its protective role.ConclusionsArtemisinin protected RPE cells from amiodarone-induced damage via the CaMKK2/AMPK/Nrf2 pathway. The in vivo experiments in mice confirmed its efficacy in preventing retinal injury caused by amiodarone. These results suggest that an artemisinin-based eye formulation could be repurposed for treating amiodarone-induced ocular toxicity.

Energy‑stress‑mediated activation of AMPK sensitizes MPS1 kinase inhibition in triple‑negative breast cancer.

Monopolar spindle 1 kinase (Mps1, also known as TTK protein kinase) inhibitors exert marked anticancer effects against triple‑negative breast cancer (TNBC) by causing genomic instability and cell death. As aneuploid cells are vulnerable to compounds that induce energy stress through adenosine monophosphate‑activated protein kinase (AMPK) activation, the synergistic effect of Mps1/TTK inhibition and AMPK activation was investigated in the present study. The combined effects of CFI‑402257, an Mps1/TTK inhibitor, and AICAR, an AMPK agonist, were evaluated in terms of cytotoxicity, cell‑cycle distribution, and in vivo xenograft models. Additional molecular mechanistic studies were conducted to elucidate the mechanisms underlying apoptosis and autophagic cell death. The combination of CFI‑402257 and AICAR showed selective cytotoxicity in a TNBC cell line. The formation of polyploid cells was attenuated, and apoptosis was increased by the combination treatment, which also induced autophagy through dual inhibition of the PI3K/Akt/mTOR and mitogen‑activated protein kinase (MAPK) signaling pathways. Additionally, the combination therapy showed strongly improved efficacy in comparison with CFI‑402257 and AICAR monotherapy in the MDA‑MB‑231 xenograft model. The present study suggested that the combination of CFI‑402257 and AICAR is a promising therapeutic strategy for TNBC.

The activation of adenosine monophosphate-activated protein kinase inhibits the migration of tongue squamous cell carcinoma cells by targeting Claudin-1 via epithelial-mesenchymal transition.

The role of Claudin-1 in tongue squamous cell carcinoma (TSCC) metastasis needs further clarification, particularly its impact on cell migration. Herein, our study aims to investigate the role of Claudin-1 in TSCC cell migration and its underlying mechanisms. 36 TSCC tissue samples underwent immunohistochemical staining for Claudin-1. Western blotting and immunofluorescence analyses were conducted to evaluate Claudin-1 expression and distribution in TSCC cells. Claudin-1 knockdown cell lines were established using short hairpin RNA transfection. Migration effects were assessed through wound healing assays. Furthermore, the expression of EMT-associated molecules was measured via western blotting. Claudin-1 expression decreased as TSCC malignancy increased. Adenosine monophosphate-activated protein kinase (AMPK) activation led to increased Claudin-1 expression and membrane translocation, inhibiting TSCC cell migration and epithelial-mesenchymal transition (EMT). Conversely, Claudin-1 knockdown reversed these inhibitory effects on migration and EMT caused by AMPK activation. Our results indicated that AMPK activation suppresses TSCC cell migration by targeting Claudin-1 and EMT pathways.

Features of lipid metabolism in patients with type 2 diabetes mellitus and gout

The aim: To study the relationship between lipid metabolism parameters, chemerin, and adenosine monophosphate-activated protein kinase (AMPK) activity in patients with type 2 diabetes mellitus (T2DM), as well as in patients with a combined course of T2DM and gout. Materials and methods. To assess lipid metabolism disorders, 100 patients were examined and divided into 2 groups: - 1st group – patients with T2DM and gout (n=70), 2nd group – patients with gout (n=30), control group (CG) - practically healthy individuals (n=20). The levels of total cholesterol (TC), triglycerides, high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL), and very low-density lipoprotein cholesterol (VLDL) were analyzed. As markers of insulin resistance (IR), the content of AMPK and chemerin was investigated. Statistical data processing was carried out using the statistical data processing program package version 8.0 STATISTICA (StatSoft Inc). The results. A significant difference was found between the levels of lipid parameters (except HDL) when comparing patients with the combined pathology of T2DM and gout, with a monocourse of gout and representatives of CG (р<0.001). It was also found that among lipidogram indicators, in all groups, an inverse correlation of AMPK value with LDL level was found (strong for patients of the 1st group and medium strength for representatives of the 2nd group and CG). Another indicator with which AMPK levels in all groups were statistically reliably correlated was TC. The presence of a direct correlation between the levels of LDL and chemerin in the 2nd group and CG, as well as the levels of TC and chemerin in patients with a combination of T2DM with gout and an inverse correlation in the other groups (all p<0.05) was established. Conclusions: Statistically significant relationships were found between lipid metabolism indicators, chemerin and AMPK activity in patients with T2DM, as well as in patients with combined course of T2DM and gout

Salicylate induces epithelial actin reorganization via activation of the AMP-activated protein kinase and promotes wound healing and contraction in mice

Wounds that occur in adults form scars due to fibrosis, whereas those in embryos regenerate. If wound healing in embryos is mimicked in adults, scarring can be reduced. We found that mouse fetuses could regenerate tissues up to embryonic day (E) 13, but visible scars remained thereafter. This regeneration pattern requires actin cable formation at the epithelial wound margin via activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK). Here, we investigated whether the AMPK-activating effect of salicylate, an anti-inflammatory drug, promotes regenerative wound healing. Salicylate administration resulted in actin cable formation and complete wound regeneration in E14 fetuses, in which scarring should have normally occurred, and promoted contraction of the panniculus carnosus muscle, resulting in complete wound regeneration. In vitro, salicylate further induced actin remodeling in mouse epidermal keratinocytes in a manner dependent on cell and substrate target-specific AMPK activation and subsequent regulation of Rac1 signaling. Furthermore, salicylate promoted epithelialization, enhanced panniculus carnosus muscle contraction, and inhibited scar formation in adult mice. Administration of salicylates to wounds immediately after injury may be a novel method for preventing scarring by promoting a wound healing pattern similar to that of embryonic wounds.

Role of AMPK-regulated autophagy in retinal pigment epithelial cell homeostasis: A review.

The retinal pigment epithelium (RPE) is a regularly arranged monolayer of cells in the outermost layer of the retina. It is crucial for transporting nutrients and metabolic substances in the retina and maintaining the retinal barrier. RPE dysfunction causes diseases related to vision loss. Thus, understanding the mechanisms involved in normal RPE function is vital. Adenosine monophosphate-activated protein kinase (AMPK) is an RPE energy sensor regulating various signaling and metabolic pathways to maintain cellular energetic homeostasis. AMPK activation is involved in multiple signaling pathways regulated by autophagy in the RPE, thereby protecting the cells from oxidative stress and slowing RPE degeneration. In this review, we attempt to broaden the understanding of the pathogenesis of RPE dysfunction by focusing on the role and mechanism of AMPK regulation of autophagy in the RPE. The correlation between RPE cellular homeostasis and role of AMPK was determined by analyzing the structure and mechanism of AMPK and its signaling pathway in autophagy. The protective effect of AMPK-regulated autophagy on the RPE for gaining insights into the regulatory pathways of RPE dysfunction has been discussed.

HL156A, an AMP-Activated Protein Kinase Activator, Inhibits Cyst Growth in Autosomal Dominant Polycystic Kidney Disease.

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent genetic kidney disorder. While metformin has demonstrated the ability to inhibit cyst growth in animal models of ADPKD via activation of adenosine monophosphate-activated protein kinase (AMPK), its effectiveness in humans is limited due to its low potency. This study explored the impact of HL156A, a new and more potent AMPK activator, in a mouse model of ADPKD. To investigate whether HL156A inhibits the proliferation of renal cyst cells in ADPKD in vitro, exogenous human telomerase reverse transcriptase (hTERT)-immortalized renal cyst cells from ADPKD patients were treated with HL156A, and an MTT (dimethylthiazol-diphenyltetrazolium bromide) assay was performed. To assess the cyst-inhibitory effect of HL156A in vivo, we generated Pkd1 conditional knockout (KO) mice with aquaporin 2 (AQP2)-Cre, which selectively expresses Cre recombinase in the collecting duct. The effectiveness of HL156A in inhibiting cyst growth and improving renal function was confirmed by measuring the number of cysts and blood urea nitrogen (BUN) levels in the collecting duct-specific Pkd1 KO mice. When cyst cells were treated with up to 20 µM of metformin or HL156A, HL156A reduced cell viability by 25% starting at a concentration of 5 µM, whereas metformin showed no effect. When AQP2-Cre male mice were crossed with Pkd1flox/flox female mice, and when AQP2-Cre female mice were crossed with Pkd1flox/flox male mice, the number of litters produced by both groups was comparable. In collecting duct-specific Pkd1 KO mice, HL156A was found to inhibit cyst growth, reducing both the number and size of cysts. Furthermore, it was confirmed that kidney function improved as HL156A treatment led to a reduction in elevated BUN levels. Lastly, it was observed that the increase in AMPK phosphorylation induced by HL156A decreased ERK phosphorylation and α-SMA expression. HL156A has potential as a drug that can restore kidney function in ADPKD patients by inhibiting cyst growth.

Astragaloside IV promotes cerebral tissue restoration through activating AMPK- mediated microglia polarization in ischemic stroke rats

Ethnopharmacological relevanceAstragaloside IV (AS), a key active ingredient obtained from Chinese herb Astragalus mongholicus Bunge, exerts potent neuroprotective and anti-inflammatory effects for treating neurodegenerative diseases. However, mechanisms of AS on improvement of ischemic brain tissue repair remain unclear. Aim of the studyThis research aims at using magnetic resonance imaging (MRI) to noninvasively determine whether AS facilitates brain tissue repair, and investigating whether AS exerts brain remodeling through adenosine monophosphate-activated protein kinase (AMPK) metabolic signaling regulating key glycolytic enzymes and energy transporters, thereby impacting microglia polarization. Materials and methodsIschemic stroke model in male Sprague–Dawley rats were induced through permanent occlusion of the middle cerebral artery (MCAO). Infarct volume, the alterations of brain microstructure and nerve fibers reorganization were examined by multi-parametric MRI. The pathological damages of myelinated axons and microglia polarization surrounding infarct tissue were detected using pathological techniques. Furthermore, M1/M2 microglia polarization associated protein, glycolytic rate-limiting enzymes, energy transporters and AMPK/mammalian target of rapamycin (mTOR)/hypoxia inducible factor-1α (HIF-1α) signal were examined both in ischemic stroke rats and BV2 microglia treated with lipopolysaccharide (LPS) + interferon-γ (IFN-γ) by western blotting. ResultsMRI revealed that AS obviously decreased infarct volume, relieved brain microstructure damage and improved nerve fibers reorganization in ischemic stroke rats. Histological tests supported MRI findings. Notably, AS promoted microglia M2 and reduced M1 polarization, induced the AMPK activation accompanied with decreased levels of phosphorylated mTOR and HIF-1α. Moreover, AS suppressed the expression of glycolytic rate-limiting enzymes and energy transporters in ischemic stroke rats and BV2 microglia. In contrast, these beneficial effects were greatly blocked by AMPK inhibitor compound C. ConclusionOverall, these results collectively suggested that AS facilitated tissue remodeling that may be partially through modulating polarization of microglia in AMPK- dependent metabolic pathways after ischemic stroke.

Ginkgolide C attenuated Western diet-induced non-alcoholic fatty liver disease via increasing AMPK activation.

Non-alcoholic steatohepatitis (NASH) is a metabolic dysregulation-related disorder that is generally characterized by lipid metabolism dysfunction and an excessive inflammatory response. Currently, there are no authorized pharmacological interventions specifically designed to manage NASH. It has been reported that Ginkgolide C exhibits anti-inflammatory effects and modulates lipid metabolism. However, the impact and function of Ginkgolide C in diet-induced NASH are unclear. In this study, mice were induced by a Western Diet (WD) with different doses of Ginkgolide C with or without Compound C (adenosine 5 '-monophosphate (AMP)-activated protein kinase (AMPK) inhibitor). The effects of Ginkgolide C were evaluated by assessing liver damage, steatosis, fibrosis, and AMPK expression. The results showed that Ginkgolide C significantly alleviated liver damage, steatosis, and fibrosis in the WD-induced mice. In addition, Ginkgolide C markedly improved insulin resistance and attenuated hepatic inflammation. Importantly, Ginkgolide C exerted protective effects by activating the AMPK signaling pathway, which was reversed by AMPK inhibition. Ginkgolide C alleviated NASH induced by WD in mice, potentially via activating the AMPK signaling pathway.