AMP-activated Protein Kinase Inhibitor Research Articles

Ginsenoside Rg1 inhibits multiple myeloma and overcomes bortezomib resistance through AMPK-mTOR pathway

BackgroundThe resistance of multiple myeloma (MM) to bortezomib (BTZ) has brought multiple challenges to its clinical use. Numerous ginsenosides have potential anti-tumor effects, however, the research on the role of Rg1 in MM has not been reported. ObjectiveTo examine the inhibitory impact of Rg1 on the growth of MM and reduce the drug resistance of MM to BTZ through in vivo and in vitro experiments, and to explore their potential mechanism. MethodsBTZ drug-resistant cell line RPMI8226R was constructed. Mouse tumor-bearing model was developed by abdominal subcutaneous injection of MM cells. MM cells were treated with AMPK inhibitor Compound C or autophagy inhibitor Chloroquine together with Rg1. RPMI8226R cells were treated with BTZ and Rg1. Cell multiplication was detected using Methylthiazolyldiphenyl-tetrazolium bromide assay. Apoptosis was assessed using flow cytometry. Immunofluorescence assay was employed to assess the autophagy markers LC3. Western blot was utilized to assess the protein expression. Immunohistochemistry was used to detect cell proliferation and apoptosis in tumor tissues. ResultsIn vitro experiments demonstrated that Rg1 could hinder the proliferation of MM cells, promote apoptosis and enhance autophagy. Rg1 could also increase the sensitivity of RPMI8226R to BTZ. In vivo experiments illustrated that Rg1 could hinder the development of MM cells in mice, weaken the proliferation of tumor cells and enhance their apoptosis. Further study found that the anti-MM impact of Rg1 was linked to AMPK-mTOR pathway, the autophagy degree of RPMI8226R was higher than that of RPMI8226, and that Rg1 could inhibit MM and overcome drug resistance through autophagy induced by AMPK-mTOR pathway. ConclusionRg1 has significant anti-MM effect and can overcome BTZ resistance, and its potential mechanism is related to the regulation of autophagy induced by AMPK-mTOR pathway. Rg1 is a promising adjuvant drug for the treatment of MM.

Reprogramming of Energy Metabolism in Human PKD1 Polycystic Kidney Disease: A Systems Biology Analysis.

Multiple alterations of cellular metabolism have been documented in experimental studies of autosomal dominant polycystic kidney disease (ADPKD) and are thought to contribute to its pathogenesis. To elucidate the molecular pathways and transcriptional regulators associated with the metabolic changes of renal cysts in ADPKD, we compared global gene expression data from human PKD1 renal cysts, minimally cystic tissues (MCT) from the same patients, and healthy human kidney cortical tissue samples. We found gene expression profiles of PKD1 renal cysts were consistent with the Warburg effect with gene pathway changes favoring increased cellular glucose uptake and lactate production, instead of pyruvate oxidation. Additionally, mitochondrial energy metabolism was globally depressed, associated with downregulation of gene pathways related to fatty acid oxidation (FAO), branched-chain amino acid (BCAA) degradation, the Krebs cycle, and oxidative phosphorylation (OXPHOS) in renal cysts. Activation of mTORC1 and its two target proto-oncogenes, HIF-1α and MYC, was predicted to drive the expression of multiple genes involved in the observed metabolic reprogramming (e.g., GLUT3, HK1/HK2, ALDOA, ENO2, PKM, LDHA/LDHB, MCT4, PDHA1, PDK1/3, MPC1/2, CPT2, BCAT1, NAMPT); indeed, their predicted expression patterns were confirmed by our data. Conversely, we found AMPK inhibition was predicted in renal cysts. AMPK inhibition was associated with decreased expression of PGC-1α, a transcriptional coactivator for transcription factors PPARα, ERRα, and ERRγ, all of which play a critical role in regulating oxidative metabolism and mitochondrial biogenesis. These data provide a comprehensive map of metabolic pathway reprogramming in ADPKD and highlight nodes of regulation that may serve as targets for therapeutic intervention.

Platelet-derived exosomes alleviate tendon stem/progenitor cell senescence and ferroptosis by regulating AMPK/Nrf2/GPX4 signaling and improve tendon-bone junction regeneration in rats

BackgroundTendon stem/progenitor cell (TSPC) senescence contributes to tendon degeneration and impaired tendon repair, resulting in age-related tendon disorders. Ferroptosis, a unique iron-dependent form of programmed cell death, might participate in the process of senescence. However, whether ferroptosis plays a role in TSPC senescence and tendon regeneration remains unclear. Recent studies reported that Platelet-derived exosomes (PL-Exos) might provide significant advantages in musculoskeletal regeneration and inflammation regulation. The effects and mechanism of PL-Exos on TSPC senescence and tendon regeneration are worthy of further study.MethodsHerein, we examined the role of ferroptosis in the pathogenesis of TSPC senescence. PL-Exos were isolated and determined by TEM, particle size analysis, western blot and mass spectrometry identification. We investigated the function and underlying mechanisms of PL-Exos in TSPC senescence and ferroptosis via western blot, real-time quantitative polymerase chain reaction, and immunofluorescence analysis in vitro. Tendon regeneration was evaluated by HE staining, Safranin-O staining, and biomechanical tests in a rotator cuff tear model in rats.ResultsWe discovered that ferroptosis was involved in senescent TSPCs. Furthermore, PL-Exos mitigated the aging phenotypes and ferroptosis of TSPCs induced by t-BHP and preserved their proliferation and tenogenic capacity. The in vivo animal results indicated that PL-Exos improved tendon-bone healing properties and mechanical strength. Mechanistically, PL-Exos activated AMPK phosphorylation and the downstream nuclear factor erythroid 2-related factor 2 (Nrf2)/glutathione peroxidase 4 (GPX4) signaling pathway, leading to the suppression of lipid peroxidation. AMPK inhibition or GPX4 inhibition blocked the protective effect of PL-Exos against t-BHP-induced ferroptosis and senescence.ConclusionIn conclusion, ferroptosis might play a crucial role in TSPC aging. AMPK/Nrf2/GPX4 activation by PL-Exos was found to inhibit ferroptosis, consequently leading to the suppression of senescence in TSPCs. Our results provided new theoretical evidence for the potential application of PL-Exos to restrain tendon degeneration and promote tendon regeneration.

Ecklonia cava Polyphenols Have a Preventive Effect on Parkinson's Disease through the Activation of the Nrf2-ARE Pathway.

Parkinson's disease (PD) is a degenerative neurological disorder defined by the deterioration and loss of dopamine-producing neurons in the substantia nigra, leading to a range of motor impairments and non-motor symptoms. The underlying mechanism of this neurodegeneration remains unclear. This research examined the neuroprotective properties of Ecklonia cava polyphenols (ECPs) in mitigating neuronal damage induced by rotenone via the activation of the nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway. Using human neuroblastoma SH-SY5Y cells and PD model mice, we found that ECP, rich in the antioxidant polyphenol phlorotannin, boosted the gene expression and functionality of the antioxidant enzyme NAD(P)H quinone oxidoreductase-1. ECP also promoted Nrf2 nuclear translocation and increased p62 expression, suggesting that p62 helps sustain Nrf2 activation via a positive feedback loop. The neuroprotective effect of ECP was significantly reduced by Compound C (CC), an AMP-activated protein kinase (AMPK) inhibitor, which also suppressed Nrf2 nuclear translocation. In PD model mice, ECPs improved motor functions impaired by rotenone, as assessed by the pole test and wire-hanging test, and restored intestinal motor function and colon tissue morphology. Additionally, ECPs increased tyrosine hydroxylase expression in the substantia nigra, indicating a protective effect on dopaminergic neurons. These findings suggest that ECP has a preventative effect on PD.

Selective Activation of G Protein-Coupled Estrogen Receptor 1 (GPER1) Reduces ER Stress and Pyroptosis via AMPK Signaling Pathway in Experimental Subarachnoid Hemorrhage.

Neuroinflammation is a critical pathogenic event following hemorrhagic stroke. Endoplasmic reticulum (ER) stress-induced apoptosis and nucleotide-binding domain, leucine-rich repeat, and pyrin domain-containing protein 3(NLRP3)-associated pyroptosis can contribute to the escalation of neuroinflammatory responses, leading to increased brain damage. G protein-coupled estrogen receptor 1(GPER1), as the most extensively characterized brain-derived estrogen, was reported to trigger neuroprotective effects. However, the anti-apoptotic and anti-pyroptotic effect of GPER1 activation and the underlying mechanism has not been fully elucidated. We established the experimental SAH model by intravascular perforation. The GPER1 selective agonist G1 was intravenously administered 1h following SAH. For mechanistic exploration, the selective inhibitor of adenosine monophosphate-activated protein kinase (AMPK), dorsomorphin, was administered via intracerebroventricular injection 30min prior to SAH induction. Post-SAH assessments included SAH grade, the short-term and long-term neurological outcomes, brain edema, cerebral blood flow, transmission electron microscopy (TEM), western blot (WB), ELISA, TUNEL staining, Fluoro-Jade C staining (FJC), and immunofluorescence staining. The expression of GPER1 was observed to elevate at 6h and peaked at 24h subsequent to SAH, predominantly co-localized with neurons. Post-treatment with G1 markedly ameliorated both the short-term and long-term neurological deficits of SAH mouse, as well as inhibiting the expression of neuronal ER stress-associated apoptotic proteins (i.e., CHOP, GRP78, Caspase-12, Cleaved Caspase-3, Bax, Bcl2) and pyroptosis-associated proteins (i.e., NLRP3, ASC, Cleaved Caspase-1). Additionally, our research revealed that inhibition of AMPK with dorsomorphin attenuated the neuroprotective effects of G1. This was accompanied by modifications in the molecular pathways associated with ER stress-induced apoptosis and pyroptosis. These data herein elucidated that GPER1 exerted neuroprotective effects by mitigating neuroinflammation in an AMPK-dependent manner, which modulates neuronal ER stress-associated apoptosis and pyroptosis. Boosting the anti-apoptotic and anti-pyroptotic effect by activating GPER1 may be an efficient treatment strategy for SAH patients.

The Survival of Human Intervertebral Disc Nucleus Pulposus Cells under Oxidative Stress Relies on the Autophagy Triggered by Delphinidin.

Delphinidin (Delp), a natural antioxidant, has shown promise in treating age-related ailments such as osteoarthritis (OA). This study investigates the impact of delphinidin on intervertebral disc degeneration (IVDD) using human nucleus pulposus cells (hNPCs) subjected to hydrogen peroxide. Various molecular and cellular assays were employed to assess senescence, extracellular matrix (ECM) degradation markers, and the activation of AMPK and autophagy pathways. Initially, oxidative stress (OS)-induced hNPCs exhibited notably elevated levels of senescence markers like p53 and p21, which were mitigated by Delp treatment. Additionally, Delp attenuated IVDD characteristics including apoptosis and ECM degradation markers in OS-induced senescence (OSIS) hNPCs by downregulating MMP-13 and ADAMTS-5 while upregulating COL2A1 and aggrecans. Furthermore, Delp reversed the increased ROS production and reduced autophagy activation observed in OSIS hNPCs. Interestingly, the ability of Delp to regulate cellular senescence and ECM balance in OSIS hNPCs was hindered by autophagy inhibition using CQ. Remarkably, Delp upregulated SIRT1 and phosphorylated AMPK expression while downregulating mTOR phosphorylation in the presence of AICAR (AMPK activator), and this effect was reversed by Compound C, AMPK inhibitor. In summary, our findings suggest that Delp can safeguard hNPCs from oxidative stress by promoting autophagy through the SIRT1/AMPK/mTOR pathway.

A Novel AMPK Inhibitor Sensitizes Pancreatic Cancer Cells to Ferroptosis Induction.

Cancer cells must develop strategies to adapt to the dynamically changing stresses caused by intrinsic or extrinsic processes, or therapeutic agents. Metabolic adaptability is crucial to mitigate such challenges. Considering metabolism as a central node of adaptability, it is focused on an energy sensor, the AMP-activated protein kinase (AMPK). In a subtype of pancreatic ductal adenocarcinoma (PDAC)elevated AMPK expression and phosphorylation is identified. Using drug repurposing that combined screening experiments and chemoproteomic affinity profiling, it is identified and characterized PF-3758309, initially developed as an inhibitor of PAK4, as an AMPK inhibitor. PF-3758309 shows activity in pre-clinical PDAC models, including primary patient-derived organoids. Genetic loss-of-function experiments showed that AMPK limits the induction of ferroptosis, and consequently, PF-3758309 treatment restores the sensitivity toward ferroptosis inducers. The work established a chemical scaffold for the development of specific AMPK-targeting compounds and deciphered the framework for the development of AMPK inhibitor-based combination therapies tailored for PDAC.

Cytarabine prevents neuronal damage by enhancing AMPK to stimulate PINK1 / Parkin-involved mitophagy in Parkinson's disease model

Parkinson's disease (PD) is a common age-related neurodegenerative disorder, which may be largely due to the mitochondrial dysfunction and impaired mitophagy. Thus, it is of great importance to seek novel therapeutic strategies for PD targeting mitochondrial function and mitophagy. Cytarabine is a marine-derived antimetabolite used in the treatment of acute leukemia, which is also used in the study of the nervous system. In this study, we found that cytarabine pretreatment significantly inhibited the apoptosis and necrosis in the ROT-induced SH-SY5Y cell PD model and reduced the oxidative stress, as evidenced by the reduced MDA levels and the increased levels of SOD, GSH, and total antioxidant capacity. Cytarabine can also enhance mitochondrial vitality, improve mitochondrial respiratory function, and preserve mitochondrial morphology. Cytarabine also enhanced the expression of the mitophagy-related proteins PINK1, Parkin, VDAC1, and DJ-1, and its actions can be reversed by treatment with AMPK inhibitor - Compound C (CC), suggesting that AMPK activation may be involved in cytarabine-enhanced mitophagy. Furthermore, cytarabine can also ameliorate the motor symptoms in the MPTP-induced PD-like mice model, and attenuate the neuropathy in the substantia nigra (SN) of PD mice, while Compound C antagonized cytarabine's beneficial effects. In summary, marine-derived compound cytarabine could resist neurological damage both in vitro and in vivo by activating AMPK to increase PINK1/Parkin-induced mitophagy, serving as a promising disease modulator for treating neurodegenerative disease.

Liguzinediol potentiates the metabolic remodeling by activating the AMPK/SIRT3 pathway and represses Caspase-3/GSDME-mediated pyroptosis to ameliorate cardiotoxicity

BackgroundLiguzinediol (Lig) has emerged as a promising candidate for mitigating Doxorubicin (DOX)-induced cardiotoxicity, a significant limitation in the clinical application of this widely used antineoplastic drug known for its efficacy. This study aimed to explore the effects and potential mechanisms underlying Lig’s protective role against DOX-induced cardiotoxicity.MethodsC57BL/6 mice were treated with DOX. Cardiac function changes were observed by echocardiography. Cardiac structure changes were observed by HE and Masson staining. Immunofluorescence was applied to visualize the cardiomyocyte apoptosis. Western blotting was used to detect the expression levels of AMP-activated protein kinase (AMPK), sirtuin 3 (SIRT3), Caspase-3 and gasdermin E N-terminal fragment (GSDME-N). These experiments confirmed that Lig had an ameliorative effect on DOX-induced cardiotoxicity in mice.ResultsThe results demonstrated that Lig effectively countered myocardial oxidative stress by modulating intracellular levels of reactive oxygen species (ROS), malondialdehyde (MDA), and superoxide dismutase (SOD). Lig reduced levels of creatine kinase (CK) and lactate dehydrogenase (LDH), while ameliorating histopathological changes and improving electrocardiogram profiles in vivo. Furthermore, the study revealed that Lig activated the AMPK/SIRT3 pathway, thereby enhancing mitochondrial function and attenuating myocardial cell apoptosis. In experiments with H9C2 cells treated with DOX, co-administration of the AMPK inhibitor compound C (CC) led to a significant increase in intracellular ROS levels. Lig intervention reversed these effects, along with the downregulation of GSDME-N, interleukin-1β (IL-1β), and interleukin-6 (IL-6), suggesting a potential role of Lig in mitigating Caspase-3/GSDME-mediated pyroptosis.ConclusionThe findings of this study suggest that Lig effectively alleviates DOX-induced cardiotoxicity through the activation of the AMPK/SIRT3 pathway, thereby presenting itself as a natural product with therapeutic potential for preventing DOX-associated cardiotoxicity. This novel approach may pave the way for the development of alternative strategies in the clinical management of DOX-induced cardiac complications.

Tamoxifen modulates nutrition deprivation-induced ER stress through AMPK-mediated ER-phagy in breast cancer cells.

Rapid proliferation and nutrition starvation in the tumor microenvironment pose significant challenges to cellular protein homeostasis. The accumulation of misfolded proteins in the endoplasmic reticulum lumen induces stress on cells and causes irreversible damage to cells if unresolved. Emerging reports emphasize the influence of the tumor microenvironment on therapeutic molecule efficacy and treatment outcomes. Hence, we aimed to understand the influence of tamoxifen on the cellular adaptation to endoplasmic reticulum stress during metabolic stress in breast cancer cells. Nutrition deprivation induces endoplasmic reticulum stress (ER stress), and the unfolded protein response (UPR) in breast cancer cells was confirmed by a Thioflavin B assay and western blotting. Tamoxifen-indued ER-phagy was studied using an MCD assay, confocal microscopy, and western blotting. Nutrition deprivation induces ER stress in breast cancer cells. Interestingly, tamoxifen modulates the nutrition deprivation-induced endoplasmic reticulum stress through enhancing the selective ER-phagy, a specialized autophagy. The tamoxifen-induced ER-phagy is mediated by AMPK activation. The pharmacological inhibition of AMPK blocks tamoxifen-induced ER-phagy and tamoxifen modulatory effect on ER stress during nutrition deprivation. Tamoxifen modulates ER stress by inducing ER-phagy through AMPK, thereby, may support breast cancer cell survival during nutrition deprivation conditions.

Metformin-induced oxidative stress inhibits LNCaP prostate cancer cell survival.

Preclinical and clinical studies over the past several decades have indicated the potential value of metformin, a widely utilized treatment for Type 2 diabetes, in prostate cancer therapy. Notably, these studies demonstrated metformin's pleiotropic effects on several molecular and metabolic pathways, such as androgen signaling, cell cycle, and cellular bioenergetics. In this study we investigated the role of metformin in regulating intracellular redox status and cell survival in LNCaP prostate cancer cells. The cytotoxic effects of metformin with or without the presence of SBI0206965 (AMPK inhibitor) on LNCaP cells were determined using MTT and trypan blue exclusion assays. Seahorse XP extracellular analysis, Liquid Chromatography/ Mass Spectrophotometry (LC/MS), and 2,7- and Dichlorofluoresin diacetate (DCFDA) assay were used to assess the effects of metformin on cellular bioenergetics, redox status, and redox-related metabolites. mRNA expression and protein concentration of redox-related enzymes were measured using Real Time-qPCR and ELISA assay, respectively. Independently of AMP-activated protein kinase, metformin exhibited a dose- and time-dependent inhibition of LNCaP cell survival, a response mitigated by glutathione or N-acetylcysteine (ROS scavengers) treatment. Notably, these findings were concomitant with a decline in ATP levels and the inhibition of oxidative phosphorylation. The results further indicated metformin's induction of reactive oxygen species, which significantly decreased glutathione levels and the ratio of reduced to oxidized glutathione, as well as the transsulfuration metabolite, cystathionine. Consistent with an induction of oxidative stress condition, metformin increased mRNA levels of the master redox transcription factor Nrf-2 (nuclear factor erythroid-derived 2-like), as well as transsulfuration enzymes cystathionine beta-synthase and cystathionase and GSH synthesis enzymes γ-glutamylcysteine synthetase and glutathione synthetase. Our findings highlight multiple mechanisms by which metformin-induced formation of reactive oxygen species may contribute to its efficacy in prostate cancer treatment, including promotion of oxidative stress, Nrf2 activation, and modulation of redox-related pathways, leading to its anti-survival action.

Inhibitory effect of aqueous extract of Scrophularia ningpoensis on β-cell pyroptosis in diabetic mice

Scrophularia ningpoensis Hemsl. (SN) is an herbal medicine used as a functional food in China. SN has traditionally been used to treat diabetes mellitus (DM), but its mechanism of action is not well understood. Our previous study indicated that the aqueous extract of SN can reduce hepatic insulin resistance and correct the irregular shape of pancreatic islets in diabetic mice. This study aims to investigate whether the aqueous extract of SN can regulate pyroptosis in pancreatic β-cells and explore its underlying mechanisms. Db/db mice were orally given an aqueous extract of SN for eight weeks. Subsequently, their pancreatic tissues were collected for histopathological analysis and immunoblotting. Rat insulinoma (INS-1) cells were cultured either alone or with the aqueous extract of SN and evaluated for cell viability, pyroptotic body formation, AMP-activated protein kinase (AMPK) activity, the NACHT, LRR, and PYD domain-containing protein 3 (NLRP3) inflammasome and gasdermin D (GSDMD) activation, and reactive oxygen species (ROS) production under high glucose (HG) exposure conditions. The aqueous extract of SN reduced insulitis and pancreatic β-cell death in db/db mice. Increased AMPK phosphorylation and decreased NLRP3 inflammasome and GSDMD activation were observed in pancreatic tissues after administration of the aqueous extract of SN. In vitro, the aqueous extract of SN increased cell viability and AMPK phosphorylation in a concentration-dependent manner. Additionally, the aqueous extract of SN corrected excessive ROS generation, NLRP3 inflammasome and GSDMD activation, and pyroptotic body formation. Inhibition of AMPK negated these beneficial effects of the aqueous extract of SN on INS-1 cells. The study concluded that the aqueous extract of SN alleviates β-cell pyroptosis by inhibiting NLRP3/GSDMD activation in an AMPK-dependent manner.

Mammalian target of differentiation-inducing factor-1 is mitochondrial malate dehydrogenase for activation of AMP-activated protein kinase and induction of mitochondrial fission

AimsDifferentiation-inducing factor-1 (DIF-1) is a polyketide produced by Dictyostelium discoideum that inhibits growth and migration, while promoting the differentiation of Dictyostelium stalk cells through unknown mechanisms. DIF-1 localizes in stalk mitochondria. In addition to its effect on Dictyostelium, DIF-1 also inhibits growth and migration, and induces mitochondrial fission followed by mitophagy in mammalian cells, at least in part by activating AMP-activated protein kinase (AMPK). In a previous study, we found that DIF-1 binds to mitochondrial malate dehydrogenase (MDH2) and inhibits its activity in HeLa cells. In the present study, we investigated whether MDH2 serves as a pharmacological target of DIF-1 in mammalian cells. Main methodsTo examine the enzymatic activity of MDH, mitochondrial morphology, and molecular mechanisms of DIF-1 action, we conducted an MDH reverse reaction assay, immunofluorescence staining, western blotting, and RNA interference using mammalian cells such as human umbilical vein endothelial cells, human cervical cancer cells, mouse endothelial cells, and mouse breast cancer cells. Key findingsDIF-1 inhibited mitochondrial but not cytoplasmic MDH activity. Similar to DIF-1, LW6, an authentic MDH2 inhibitor, induced phosphorylation of AMPK, resulting in the phosphorylation of acetyl-CoA carboxylase (ACC) and the dephosphorylation of p70 S6 kinase with approximately the same potency. DIF-1 and LW6 induced mitochondrial fission. Furthermore, MDH2 knockdown using siRNA reproduced the DIF-1 action on the AMPK signaling and mitochondrial morphology. Conversely, an AMPK inhibitor prevented DIF-1-induced mitochondrial fission. SignificanceWe propose that MDH2 is a mammalian target of DIF-1 for the activation of AMPK and induction of mitochondrial fission.

O-GlcNAc Modification Is a Promising Therapeutic Target for Diabetic Retinopathy.

Diabetic retinopathy (DR) is a very serious diabetes complication. Changes in the O-linked N-acetylglucosamine (O-GlcNAc) modification are associated with many diseases. However, its role in DR is not fully understood. In this research, we explored the effect of O-GlcNAc modification regulation by activating AMP-activated protein kinase (AMPK) in DR, providing some evidence for clinical DR treatment in the future. Bioinformatics was used to make predictions from the database, which were validated using the serum samples of diabetic patients. As an in vivo model, diabetic mice were induced using streptozotocin (STZ) injection with/without an AMPK agonist (metformin) or an AMPK inhibitor (compound C) treatment. Electroretinogram (ERG) and H&E staining were used to evaluate the retinal functional and morphological changes. In vitro, 661 w cells were exposed to high-glucose conditions, with or without metformin treatment. Apoptosis was evaluated using TUNEL staining. The protein expression was detected using Western blot and immunofluorescence staining. The angiogenesis ability was detected using a tube formation assay. The levels of O-GlcNAc transferase (OGT) and O-GlcNAcase (OGA) in the serum changed in the DR patients in the clinic. In the diabetic mice, the ERG wave amplitude and retinal thickness decreased. In vitro, the apoptotic cell percentage and Bax expression were increased, and Bcl2 expression was decreased in the 661 w cells under high-glucose conditions. The O-GlcNAc modification was increased in DR. In addition, the expression of GFAT/TXNIP O-GlcNAc was also increased in the 661 w cells after the high-glucose treatment. Additionally, the Co-immunoprecipitation(CO-IP) results show that TXNIP interacted with the O-GlcNAc modification. However, AMPK activation ameliorated this effect. We also found that silencing the AMPKα1 subunit reversed this process. In addition, the conditioned medium of the 661 w cells may have affected the tube formation in vitro. Taken together, O-GlcNAc modification was increased in DR with photoreceptor cell degeneration and neovascularization; however, it was reversed after activating AMPK. The underlying mechanism is linked to the GFAT/TXNIP-O-GlcNAc modification signaling axis. Therefore, the AMPKα1 subunit plays a vital role in the process.

Chlormequat chloride induces hepatic steatosis by promoting mTOR/SREBP1 mediated lipogenesis via AMPK inhibition

Chlormequat chloride (CCC), a widely used plant growth regulator, is a choline analogue that has been shown to have endocrine-disrupting effects. Previous studies have shown that maternal exposure to CCC could induce hyperlipidemia and growth disruption in rat offspring. This study aims to further investigate the effects of peripubertal exposure to CCC on pubertal development and lipid homeostasis, as well as the underlying mechanisms. In vivo, male weanling rats were exposed to CCC (0, 20, 75 and 200 mg/kg bw/day) from post-natal day 21–60 via daily oral gavage. The results in rats showed that 75 mg/kg CCC treatment induced hepatic steatosis, predominantly microvesicular steatosis with a small amount of macrovesicular steatosis, in rat livers and 200 mg/kg CCC treatment induced liver damage including inflammatory infiltration, hepatic sinusoidal dilation and necrosis. In vitro, HepG2 cells were treated with CCC (0, 30, 60, 120, 240 and 480 μg/mL) for 24 h. And the results showed that CCC above 120 μg/mL induced an increase in triglyceride and neutral lipid levels of HepG2 cells. Mechanism exploration revealed that CCC treatment promoted the activation of mTOR/SREBP1 signalling pathway and inhibited activation of AMPK in both in vivo rat livers and in vitro HepG2 cells. Treatment with AMPK activator Acadesine (AICAR) could alleviate the lipid accumulation in HepG2 cells induced by CCC. Collectively, the present results indicate that CCC might induce hepatic steatosis by promoting mTOR/SREBP1 mediated lipogenesis via AMPK inhibition.

Involvement of oxidative stress-AMPK-Cx43-NLRP3 pathway in extracellular matrix remodeling of gastric smooth muscle cells in rats with diabetic gastroparesis.

This study aimed to investigate the changes in oxidative stress, adenosine monophosphate-activated protein kinase (AMPK), connexin43 (Cx43), nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) expression, and extracellular matrix (ECM) in the gastric smooth muscle tissues of rats with diabetic gastroparesis (DGP) and high glucose-cultured gastric smooth muscle cells, determine the existence of oxidative stress-AMPK-Cx43-NLRP3 pathway under high glucose condition, and the involvement of this pathway in ECM remodeling in DGP rats. The results showed that with increasing duration of diabetes, oxidation stress levels gradually increased, the AMPK activity decreased first and then increased, NLRP3, CX43 expression, and membrane/cytoplasmratio of Cx43 expression were increased in the gastric smooth muscle tissues of diabetic rats. Changes in ECM of gastric smooth muscle cells wereobserved in DGP rats. The DGP group showed higher collagen type I content, increased expression of Caspase-1, transforming growth factor-beta 3 (TGF-β3), and matrix metalloproteinase-2 (MMP-2), decreased tissue inhibitor of metalloproteinase-1 (TIMP-1) expression, and higher interleukin-1betacontent when compared with the control group. For gastric smooth muscle cells cultured under higher glucose, the MMP-2 and TGF-β3 expression wasdecreased, TGF-β1 and TIMP-1 expression was increased, the interleukin-1betacontent was decreased in cells after inhibition of NLRP3 expression; the NLRP3 and Caspase-1expression was decreased, and adenosine triphosphate content was lower after inhibition of Cx43; the expression of NLRP3, Caspase-1, P2X7, and the membrane/cytoplasm ratio of CX43 expression was decreased in cells after inhibition of AMPK and oxidative stress, the phospho-AMPK expression was also decreased after suppressing oxidative stress. Our findings suggest that high glucose induced the activation of the AMPK-Cx43-NLRP3 pathway through oxidative stress, and this pathway was involved in the ECM remodeling of gastric smooth muscles in DGP rats by regulating the biological functions of TGF-β3, TGF-β1, MMP-2, and TIMP-1.

Benzoylaconine Protects Skeletal Muscle Against Ischemia-Reperfusion Injury Through Activation of IF1-Dependent AMPK/Nrf2 Axis.

Aconitum carmichaelii (Fuzi) has been conventionally used to cure a variety of ailments, such as pain, cold sensations, and numbness of limb muscles (Bi Zheng) in China. Our prior investigations identified Benzoylaconine (BAC) as a bioactive alkaloid derived from Aconitum carmichaelii, with other studies also demonstrating its significant pharmacological potential. This study aimed to explore the potential of BAC as a protective agent against skeletal muscle ischemia-reperfusion (I/R) injury and to elucidate the underlying mechanisms. In vivo models involved subjecting Sprague-Dawley rats to I/R through femoral artery ligation followed by reperfusion, while in vitro models utilized C2C12 cells subjected to hypoxia/reoxygenation (H/R). CCK-8 assay was used to assess cell viability. TUNEL staining and flow cytometric analysis were used to measure cell apoptosis. Biochemical assay was used to assess skeletal muscle injury and oxidative stress. Immunofluorescence and Western blot were performed to determine protein levels. BAC effectively protected muscle tissue from I/R injury, enhancing cell viability (p<0.01), elevating SOD levels (p<0.05), and reducing CK (p<0.01), LDH (p<0.01), ROS (p<0.01), MDA (p<0.01), and apoptosis-related molecules in vivo and in vitro (p<0.05, p<0.01). Mechanistically, BAC increased the expression of IF1, phosphorylated AMPK, facilitated the translocation of nuclear Nrf2, and induced the expression of HO-1 (p<0.01). Notably, AMPK inhibitor Compound C significantly hindered the ability of BAC to ameliorate H/R-induced cell injury (p<0.05), oxidative stress(p<0.01), and apoptosis (p<0.05), as well as promote Nrf2 nuclear translocation (p<0.01). Moreover, silencing of IF1 with siRNA abolished BAC-induced activation of AMPK/Nrf2 axis (p<0.01). Our study provides novel evidence supporting the potential of BAC as a myocyte-protective agent against I/R injury, and we establish a previously unknown mechanism involving the activation of the IF1-dependent AMPK/Nrf2 axis in mediating the protective effects of BAC.

Naringenin enhances the efficacy of ferroptosis inducers by attenuating aerobic glycolysis by activating the AMPK-PGC1α signalling axis in liver cancer

Liver cancer is a heterogeneous disease characterized by poor responses to standard therapies and therefore unfavourable clinical outcomes. Understanding the characteristics of liver cancer and developing novel therapeutic strategies are imperative. Ferroptosis, a type of programmed cell death induced by lipid peroxidation, has emerged as a potential target for treatment. Naringenin, a natural compound that modulates lipid metabolism by targeting AMPK, shows promise in enhancing the efficacy of ferroptosis inducers. In this study, we utilized liver cancer cell lines and xenograft mice to explore the synergistic effects of naringenin in combination with ferroptosis inducers, examining both phenotypic outcomes and molecular mechanisms. Our study results indicate that the use of naringenin at non-toxic doses to hepatocytes can significantly enhance the anticancer effects of ferroptosis inducers (erastin, RSL3, and sorafenib). The combination index method confirmed a synergistic effect between naringenin and ferroptosis inducers. In comparison to naringenin or ferroptosis inducers alone, the combined therapy caused more robust lipid peroxidation and hence more severe ferroptotic damage to cancer cells. The inhibition of aerobic glycolysis mediated by the AMPK-PGC1α signalling axis is the key to naringenin's effect on reducing ferroptosis resistance in liver cancer, and the synergistic cytotoxic effect of naringenin and ferroptosis inducers on cancer cells was reversed after pretreatment with an AMPK inhibitor or a PGC1α inhibitor. Taken together, these findings suggest that naringenin could boost cancer cell sensitivity to ferroptosis inducers, which has potential clinical translational value.

AMPK drives both glycolytic and oxidative metabolism in murine and human T cells during graft-versus-host disease

AbstractAllogeneic T cells reprogram their metabolism during acute graft-versus-host disease (GVHD) in a process involving the cellular energy sensor adenosine monophosphate (AMP)–activated protein kinase (AMPK). Deletion of AMPK in donor T cells limits GVHD but still preserves homeostatic reconstitution and graft-versus-leukemia effects. In the current studies, murine AMPK knock-out (KO) T cells decreased oxidative metabolism at early time points posttransplant and lacked a compensatory increase in glycolysis after inhibition of the electron transport chain. Immunoprecipitation using an antibody specific to phosphorylated targets of AMPK determined that AMPK modified interactions of several glycolytic enzymes including aldolase, enolase, pyruvate kinase M, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), with enzyme assays confirming impaired aldolase and GAPDH activity in AMPK KO T cells. Importantly, these changes in glycolysis correlated with both an impaired ability of AMPK KO T cells to produce significant amounts of interferon gamma upon antigenic restimulation and a decrease in the total number of donor CD4 T cells recovered at later times posttransplant. Human T cells lacking AMPK gave similar results, with glycolytic compensation impaired both in vitro and after expansion in vivo. Xenogeneic GVHD results also mirrored those of the murine model, with reduced CD4/CD8 ratios and a significant improvement in disease severity. Together these data highlight a significant role for AMPK in controlling oxidative and glycolytic metabolism in both murine and human T cells and endorse further study of AMPK inhibition as a potential clinical target for future GVHD therapies.

GCTRP3 inhibits oophorectomy‑induced osteoporosis by activating the AMPK/SIRT1/Nrf2 signaling pathway in mice.

C1q/tumor necrosis factor‑related protein 3 (CTRP3) expression is markedly reduced in the serum of patients with osteoporosis. The present study aimed to investigate whether CTRP3 reduces bone loss in oophorectomy (OVX)‑induced mice via the AMP‑activated protein kinase (AMPK)/sirtuin 1 (SIRT1)/nuclear factor E2‑related factor 2 (Nrf2) signaling pathway. Female C57BL/6J mice and MC3T3‑E1 cells were used to construct in vivo and in vitro models of osteoporosis, respectively. The left femurs of mice were examined using micro‑computed tomography scans and bone‑related quantitative morphological evaluation was performed. Pathological changes and the number of osteoclasts in the left femurs of mice were detected using hematoxylin and eosin, and tartrate‑resistant acid phosphatase (TRAP) staining. Runt‑related transcription factor‑2 (RUNX2) expression in the left femurs was detected using immunofluorescence analysis, and the serum levels of bone resorption markers (C‑telopeptide of type I collagen and TRAP) and bone formation markers [osteocalcin (OCN) and procollagen type 1 N‑terminal propeptide] were detected. In addition, osteoblast differentiation and calcium deposits were examined in MC3T3‑E1 cells using alkaline phosphatase (ALP) and Alizarin red staining, respectively. Moreover, RUNX2, ALP and OCN expression levels were detected using reverse transcription‑quantitative PCR, and the expression levels of proteins associated with the AMPK/SIRT1/Nrf2 signaling pathway were detected using western blot analysis. The results revealed that globular CTRP3 (gCTRP3) alleviated bone loss and promoted bone formation in OVX‑induced mice. gCTRP3 also facilitated the osteogenic differentiation of MC3T3‑E1 cells through the AMPK/SIRT1/Nrf2 signaling pathway. The addition of an AMPK inhibitor (Compound C), SIRT1 inhibitor (EX527) or Nrf2 inhibitor (ML385) reduced the osteogenic differentiation of MC3T3‑E1 cells via inhibition of gCTRP3. In conclusion, gCTRP3 inhibits OVX‑induced osteoporosis by activating the AMPK/SIRT1/Nrf2 signaling pathway.