Hypoxanthine ameliorates diet-induced insulin resistance by improving hepatic lipid metabolism and gluconeogenesis via AMPK/mTOR/PPARα pathway.

AIM: Insulin resistance (IR) is a pivotal metabolic disorder associated with type 2 diabetes and metabolic syndrome. This study investigated the potential of hypoxanthine (Hx), a purine metabolite and uric acid precursor, in ameliorating IR and regulating hepatic glucose and lipid metabolism. METHODS: We utilized both in vitro IR-HepG2 cells and in vivo diet-induced IR mice to investigate the impact of Hx. The HepG2 cells were treated with Hx to evaluate its effects on glucose production and lipid deposition. Activity-based protein profiling (ABPP) was applied to identify Hx-target proteins and the underlying pathways. In vivo studies involved administration of Hx to IR mice, followed by assessments of IR-associated indices, with explores on the potential regulating mechanisms on hepatic glucose and lipid metabolism. KEY FINDINGS: Hx intervention significantly reduced glucose production and lipid deposition in a dose-dependent manner without affecting cell viability in IR-HepG2 cells. ABPP identified key Hx-target proteins engaged in fatty acid and pyruvate metabolism. In vivo, Hx treatment reduced IR severities, as evidenced by decreased HOMA-IR, fasting blood glucose, and serum lipid profiles. Histological assessments confirmed reduced liver lipid deposition. Mechanistic insights revealed that Hx suppresses hepatic gluconeogenesis and fatty acid synthesis, and promotes fatty acid oxidation via the AMPK/mTOR/PPARα pathway. SIGNIFICANCE: This study delineates a novel role of Hx in regulating hepatic metabolism, offering a potential therapeutic strategy for IR and associated metabolic disorders. The findings provide a foundation for further investigation into the role of purine metabolites in metabolic regulation and their clinical implications.

Methionine restriction alleviates diabetes-associated cognitive impairment via activation of FGF21.

Glucose metabolism disturbances may result in diabetes-associated cognitive decline (DACI). Methionine restriction (MR) diet has emerged as a potential dietary strategy for managing glucose homeostasis. However, the effects and underlying mechanisms of MR on DACI have not been fully elucidated. Here, we found that a 13-week MR (0.17 % methionine, w/w) intervention starting at 8 weeks of age improved peripheral insulin sensitivity in male db/db mice, a model for type 2 diabetes. Notably, MR significantly improved working as well as long-term memory in db/db mice, accompanied by increased PSD-95 level and reduced neuroinflammatory factors, malondialdehyde (MDA), and 8-hydroxy-2'-deoxyguanosine (8-OHdG). We speculate that this effect may be mediated by MR activating hepatic fibroblast growth factor 21 (FGF21) and the brain FGFR1/AMPK/GLUT4 signaling pathway to enhance brain glucose metabolism. To further delineate the mechanism, we used intracerebroventricular injection of adeno-associated virus to specifically knock down FGFR1 in the brain to verify the role of FGFR1 in MR-mediated DACI. It was found that the positive effects of MR on DACI were offset, reflected in decreased cognitive function, impaired synaptic plasticity, upregulated neuroinflammation, and balanced enzymes regulating reactive oxygen species (Sod1, Sod2, Nox4). Of note, the FGFR1/AMPK/GLUT4 signaling pathway and brain glucose metabolism were inhibited. In summary, our study demonstrated that MR increased peripheral insulin sensitivity, activated brain FGFR1/AMPK/GLUT4 signaling through FGF21, maintained normal glucose metabolism and redox balance in the brain, and thereby alleviated DACI. These results provide new insights into the effects of MR diet on cognitive dysfunction caused by impaired brain energy metabolism.

Atractylodes Lancea and Its Constituent, Atractylodin, Ameliorates Metabolic Dysfunction-Associated Steatotic Liver Disease via AMPK Activation.

Metabolic dysfunction-associated steatotic liver disease (MASLD), which encompasses a spectrum of conditions ranging from simple steatosis to hepatocellular carcinoma, is a growing global health concern associated with insulin resistance. Since there are limited treatment options for MASLD, this study investigated the therapeutic potential of Atractylodes lancea, a traditional herbal remedy for digestive disorders in East Asia, and its principal component, atractylodin, in treating MASLD. Following 8 weeks of high-fat diet (HFD) feeding, mice received oral doses of 30, 60, or 120 mg/kg of Atractylodes lancea. In HFD-fed mice, Atractylodes lancea treatment reduced the body weight; serum triglyceride, total cholesterol, and alanine aminotransferase levels; and hepatic lipid content. Furthermore, Atractylodes lancea significantly ameliorated fasting serum glucose, fasting serum insulin, and homeostatic model assessment of insulin resistance levels in response to HFD. Additionally, a glucose tolerance test demonstrated improved glucose homeostasis. Treatment with 5 or 10 mg/kg atractylodin also resulted in anti-obesity, anti-steatosis, and glucose-lowering effects. Atractylodin treatment resulted in the downregulation of key lipogenic genes (Srebf1, Fasn, Scd2, and Dgat2) and the upregulation of genes regulated by peroxisome proliferator-activated receptor-α. Notably, the molecular docking model suggested a robust binding affinity between atractylodin and AMP-activated protein kinase (AMPK). Atractylodin activated AMPK, which contributed to SREBP1c regulation. In conclusion, our results revealed that Atractylodes lancea and atractylodin activated the AMPK signaling pathway, leading to improvements in HFD-induced obesity, fatty liver, and glucose intolerance. This study suggests that the phytochemical, atractylodin, can be a treatment option for MASLD.

Tumor Dormancy Within the Lymphovascular Embolus Is Regulated by Multiple Metabolism-signaling Pathways.

BACKGROUND/AIM: Recently, we demonstrated that cancer dormancy is initiated within the lymphovascular tumor embolus and consists of decreased proliferation and lower mammalian target of rapamycin (mTOR) activity. In the present study, we investigated other intersecting metabolism-signaling pathways that may ultimately determine whether the lymphovascular tumor embolus remains dormant or undergoes cell death. MATERIALS AND METHODS: The present study exploited a singular patient-derived xenograft (PDX) of inflammatory breast cancer (Mary-X) that spontaneously forms high density spheroids, the in vitro equivalent of emboli. The AMPK metabolic checkpoint pathway, the mTOR nutrient-responsive cell growth pathway, the P13K/Akt intracellular quiescence regulating pathway, and the calpain-mediated E-cadherin proteolytic pathway responsible for spontaneous spheroid-genesis were also investigated, to determine their relative contributions to dormancy. RESULTS: The levels of phosphorylated AMPK proteins (AMPKα and ß subunits) decreased gradually with the formation of MARY-X spheroids in vitro. Rapamycin down-regulated mTOR activity, yet dormancy persisted. LY294002, a PI3K/Akt inhibitor, completely abolished mTOR and induced spheroid disadherence and apoptosis. Compound C (AMPK inhibitor) up-regulated mTOR and induced spheroid disadherence and apoptosis. Increasing cellular metabolism led to cell death, even in enriched medium, whereas growing the spheroids in serum-free media (starvation) did not result in further mTOR inhibition, and dormancy was maintained. CONCLUSION: An increase in our understanding of dormancy from the standpoint of internal signaling pathways might ultimately provide clues to the external stimuli (starvation, hypoxia or other not yet understood phenomena) that act through these pathways to maintain or disrupt dormancy.

Strategy for treating MAFLD: Electroacupuncture alleviates hepatic steatosis and fibrosis by enhancing AMPK mediated glycolipid metabolism and autophagy in T2DM rats.

BACKGROUND: Recent studies have highlighted type 2 diabetes (T2DM) as a significant risk factor for the development of metabolic dysfunction-associated fatty liver disease (MAFLD). This investigation aimed to assess electroacupuncture's (EA) impact on liver morphology and function in T2DM rats, furnishing experimental substantiation for its potential to stall MAFLD progression in T2DM. METHODS: T2DM rats were induced by a high-fat diet and a single intraperitoneal injection of streptozotocin, and then randomly assigned to five groups: the T2DM group, the electroacupuncture group, the metformin group, combination group of electroacupuncture and metformin, combination group of electroacupuncture and Compound C. The control group received a standard diet alongside intraperitoneal citric acid - sodium citrate solution injections. After a 6-week intervention, the effects of each group on fasting blood glucose, lipids, liver function, morphology, lipid droplet infiltration, and fibrosis were evaluated. Techniques including Western blotting, qPCR, immunohistochemistry, and immunofluorescence were employed to gauge the expression of key molecules in AMPK-associated glycolipid metabolism, insulin signaling, autophagy, and fibrosis pathways. Additionally, transmission electron microscopy facilitated the observation of liver autophagy, lipid droplets, and fibrosis. RESULTS: Our studies indicated that hyperglycemia, hyperlipidemia and IR promoted lipid accumulation, pathological and functional damage, and resulting in hepatic steatosis and fibrosis. Meanwhile, EA enhanced the activation of AMPK, which in turn improved glycolipid metabolism and autophagy through promoting the expression of PPARα/CPT1A and AMPK/mTOR pathway, inhibiting the expression of SREBP1c, PGC-1α/PCK2 and TGFß1/Smad2/3 signaling pathway, ultimately exerting its effect on ameliorating hepatic steatosis and fibrosis in T2DM rats. The above effects of EA were consistent with metformin. The combination of EA and metformin had significant advantages in increasing hepatic AMPK expression, improving liver morphology, lipid droplet infiltration, fibrosis, and reducing serum ALT levels. In addition, the ameliorating effects of EA on the progression of MAFLD in T2DM rats were partly disrupted by Compound C, an inhibitor of AMPK. CONCLUSIONS: EA upregulated hepatic AMPK expression, curtailing gluconeogenesis and lipogenesis while boosting fatty acid oxidation and autophagy levels. Consequently, it mitigated blood glucose, lipids, and insulin resistance in T2DM rats, thus impeding liver steatosis and fibrosis progression and retarding MAFLD advancement.

Magnoflorine attenuates Ang II-induced cardiac remodeling via promoting AMPK-regulated autophagy.

Background: Heart failure (HF) remains one of the most common events in the progression of hypertension. Magnoflorine (MNF) has been shown beneficial effects on the cardiovascular system. However, the action of MNF on angiotensin (Ang) II-induced cardiac remodeling and its underlying mechanisms have not yet been characterised. Here, we assessed the action of MNF in the development of hypertension-related HF. Methods: C57BL/6 male mice were subjected to Ang II through a micro-osmotic pump infusion continuously for 4 weeks to induce hypertensive HF. MNF (10 and 20 mg/kg) was administered in the final 2 weeks. Ang II content was measured by enzyme-linked immunosorbent assay (ELISA) kit. Values of ejection fraction (EF) and fractional shortening (FS) were detected using an ultrasound diagnostic instrument. The mRNA levels of hypertrophic and fibrotic genes were determined by real-time quantitative polymerase chain reaction (RT-qPCR). Haematoxylin and eosin (H&E), wheat germ agglutinin (WGA), Masson trichrome, and Sirius Red staining were used to analyse pathologic changes in heart tissues. The expression levels of phosphorylated AMP-activated protein kinase (AMPK), light chain 3 microtubule associated protein II (LC3 II) to LC3 I, and p62 were detected by western blot assay. Results: MNF significantly improved cardiac dysfunction and the content of creatine kinase-MB without altering blood pressure in Ang II-challenged mice. MNF obviously corrected the phenotypes of cardiac hypertrophy and fibrosis, including the high mRNA levels of atrial natriuretic peptide (Anp), brain natriuretic peptide (Bnp), collagen1a (Col1a1), transforming growth factor beta (Tgfb1), enlarged myocardial areas, and increased positive areas of Masson trichrome and Sirius Red staining. In addition, MNF alleviated oxidative injury, reflected by the upregulation of glutathione and the downregulation of reactive oxygen species and malondialdehyde. The activation of AMPK was elevated accompanied by an increased level of autophagy by MNF in hypertensive heart tissues. The therapeutic action of MNF was confirmed in Ang II-challenged H9c2 cells. Specifically, the AMPK inhibitor could eliminate the autophagy pathway in which MNF is involved. Conclusions: MNF has benefits in hypertension-induced cardiac remodeling, which was partially associated with the improvement of oxidative stress via the mediation of the AMPK/autophagy axis.

AMP-activated protein kinase in the amygdala and hippocampus contributes to enhanced fear memory in diabetic mice.

BACKGROUND AND PURPOSE: Diabetic patients have an increased risk of psychiatric disorders. Because hyperglycaemia increases L-lactate in the brain and L-lactate inhibits AMP-activated protein kinase (AMPK), this study investigated the role of L-lactate and AMPK in strengthened fear memory, a model for human psychiatric disorders, in diabetic mice. EXPERIMENTAL APPROACH: The diabetic model was mice injected with streptozotocin. Fear memory was measured using the conditioned fear test with low (0.45 mA) or high (0.50 mA) foot shock to cause low and high freezing, respectively. Protein levels of AMPK and phosphorylated AMPK (pAMPK) were measured by western blotting and immunohistochemistry. KEY RESULTS: At 0.45 mA, the AMPK inhibitor dorsomorphin increased freezing, which was inhibited by the AMPK activator acadesine. In contrast, at 0.50 mA, acadesine decreased freezing, which was inhibited by dorsomorphin. In diabetic mice, pAMPK was decreased in the amygdala and hippocampus. Diabetic mice showed increased freezing at 0.45 mA, which was inhibited by acadesine. In the amygdala and hippocampus, L-lactate was increased in diabetic mice and injection of L-lactate into non-diabetic mice increased freezing at 0.45 mA. In addition, L-lactate decreased pAMPK in the hippocampus, but not the amygdala, and increase in freezing induced by L-lactate was inhibited by acadesine. Dorsomorphin-induced increase in freezing was inhibited by the AMPA receptor antagonist NBQX. CONCLUSIONS AND INTERPRETATION: In diabetic mice, L-lactate is increased in the amygdala and hippocampus, possibly through hyperglycaemia, which strengthens fear memory through inhibition of AMPK and activation of glutamatergic function.

Depression exacerbates myocardial ischemia-reperfusion injury in mice via CNR2 gene and MIF-AMPK signaling pathway.

BACKGROUND: Myocardial ischemia-reperfusion(I/R)injury constitute the fundamental pathophysiology of acute myocardial infarction (AMI). Ischemic heart releases macrophage migration inhibitory factor (MIF), which activates MIF- AMPK signaling pathway. Depression is a significant risk factor for AMI. In a state of depression, peripheral expression of cannabinoid receptor 2 (CNR2) genes was downregulated. AIMS: We investigated the mechanism by which depression exacerbates myocardial I/R injury through the CNR2 and MIF-AMPK signaling pathways. METHODS: We established mouse models of depression and myocardial I/R. Left ventricular function was assessed using cardiac ultrasound and TTC staining. The protein levels of myocardial CNR2, MIF, AMPK, and ACC were determined by Western blot, while the expression level of CNR2 was measured using RT-qPCR. Additionally, MIF content in peripheral blood was quantified using ELISA. RESULTS: After I/R, the expression level of CNR2 was found to be lower in the depression group, leading to a deterioration in left heart function. Depressed mice exhibited lower secretion of MIF, accompanied by a decrease in the activation of the MIF-AMPK signaling pathway. However, injection of CNR2 agonist JWH133 prior to ischemia increased the activation of the MIF-AMPK signaling pathway, while CNR2 inhibitor AM630 decreased the activation. LIMITATIONS: Further research is needed to investigate the specific neuroendocrine mechanism affecting myocardial CNR2 expression in depression. And these experimental conclusions require further verification at the cellular level. CONCLUSIONS: The activation of CNR2 in myocardium following I/R is impeded by depression, thereby exacerbating myocardial I/R injury through attenuation of the MIF-AMPK signaling pathway activation.

Protein Kinases in Obesity, and the Kinase-Targeted Therapy.

The action of protein kinases and protein phosphatases is essential for multiple physiological responses. Each protein kinase displays its own unique substrate specificity and a regulatory mechanism that may be modulated by association with other proteins. Protein kinases are classified as dual-specificity kinases and dual-specificity phosphatases. Dual-specificity phosphatases are important signal transduction enzymes that regulate various cellular processes in coordination with protein kinases and play an important role in obesity. Impairment of insulin signaling in obesity is largely mediated by the activation of the inhibitor of kappa B-kinase beta and the c-Jun N-terminal kinase (JNK). Oxidative stress and endoplasmic reticulum (ER) stress activate the JNK pathway which suppresses insulin biosynthesis. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) are important for proper regulation of glucose metabolism in mammals at both the hormonal and cellular levels. Additionally, obesity-activated calcium/calmodulin dependent-protein kinase II/p38 suppresses insulin-induced protein kinase B phosphorylation by activating the ER stress effector, activating transcription factor-4. To alleviate lipotoxicity and insulin resistance, promising targets are pharmacologically inhibited. Nifedipine, calcium channel blocker, stimulates lipogenesis and adipogenesis by downregulating AMPK and upregulating mTOR, which thereby enhances lipid storage. Contrary to the nifedipine, metformin activates AMPK, increases fatty acid oxidation, suppresses fatty acid synthesis and deposition, and thus alleviates lipotoxicity. Obese adults with vascular endothelial dysfunction have greater endothelial cells activation of unfolded protein response stress sensors, RNA-dependent protein kinase-like ER eukaryotic initiation factor-2 alpha kinase (PERK), and activating transcription factor-6. The transcriptional regulation of adipogenesis in obesity is influenced by AGC (protein kinase A (PKA), PKG, PKC) family signaling kinases. Obesity may induce systemic oxidative stress and increase reactive oxygen species in adipocytes. An increase in intracellular oxidative stress can promote PKC-ß activation. Activated PKC-ß induces growth factor adapter Shc phosphorylation. Shc-generated peroxides reduce mitochondrial oxygen consumption and enhance triglyceride accumulation and lipotoxicity. Liraglutide attenuates mitochondrial dysfunction and reactive oxygen species generation. Co-treatment of antiobesity and antidiabetic herbal compound, berberine with antipsychotic drug olanzapine decreases the accumulation of triglyceride. While low-dose rapamycin, metformin, amlexanox, thiazolidinediones, and saroglitazar protect against insulin resistance, glucagon-like peptide-1 analog liraglutide inhibits palmitate-induced inflammation by suppressing mTOR complex 1 (mTORC1) activity and protects against lipotoxicity.

Adiponectin Resistance in Obesity: Adiponectin Leptin/Insulin Interaction.

The adiponectin (APN) levels in obesity are negatively correlated with chronic subclinical inflammation markers. The hypertrophic adipocytes cause obesity-linked insulin resistance and metabolic syndrome. Furthermore, macrophage polarization is a key determinant regulating adiponectin receptor (AdipoR1/R2) expression and differential adiponectin-mediated macrophage inflammatory responses in obese individuals. In addition to decrease in adiponectin concentrations, the decline in AdipoR1/R2 messenger ribonucleic acid (mRNA) expression leads to a decrement in adiponectin binding to cell membrane, and this turns into attenuation in the adiponectin effects. This is defined as APN resistance, and it is linked with insulin resistance in high-fat diet-fed subjects. The insulin-resistant group has a significantly higher leptin-to-APN ratio. The leptin-to-APN ratio is more than twofold higher in obese individuals. An increase in expression of AdipoRs restores insulin sensitivity and ß-oxidation of fatty acids via triggering intracellular signal cascades. The ratio of high molecular weight to total APN is defined as the APN sensitivity index (ASI). This index is correlated to insulin sensitivity. Homeostasis model of assessment (HOMA)-APN and HOMA-estimated insulin resistance (HOMA-IR) are the most suitable methods to estimate the metabolic risk in metabolic syndrome. While morbidly obese patients display a significantly higher plasma leptin and soluble (s)E-selectin concentrations, leptin-to-APN ratio, there is a significant negative correlation between leptin-to-APN ratio and sP-selectin in obese patients. When comparing the metabolic dysregulated obese group with the metabolically healthy obese group, postprandial triglyceride clearance, insulin resistance, and leptin resistance are significantly delayed following the oral fat tolerance test in the first group. A neuropeptide, Spexin (SPX), is positively correlated with the quantitative insulin sensitivity check index (QUICKI) and APN. APN resistance together with insulin resistance forms a vicious cycle. Despite normal or high APN levels, an impaired post-receptor signaling due to adaptor protein-containing pleckstrin homology domain, phosphotyrosine-binding domain, and leucine zipper motif 1 (APPL1)/APPL2 may alter APN efficiency and activity. However, APPL2 blocks adiponectin signaling through AdipoR1 and AdipoR2 because of the competitive inhibition of APPL1. APPL1, the intracellular binding partner of AdipoRs, is also an important mediator of adiponectin-dependent insulin sensitization. The elevated adiponectin levels with adiponectin resistance are compensatory responses in the condition of an unusual discordance between insulin resistance and APN unresponsiveness. Hypothalamic recombinant adeno-associated virus (rAAV)-leptin (Lep) gene therapy reduces serum APN levels, and it is a more efficient strategy for long-term weight maintenance.

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, heterocycles and 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.

[Box: see text].

The cereblon-AMPK (AMP-activated protein kinase) axis in chondrocytes regulates the pathogenesis of osteoarthritis.

OBJECTIVE: AMP-activated protein kinase (AMPK) dysregulation is implicated in osteoarthritis (OA), but the mechanisms underlying this dysregulation remain unclear. We investigated the role of cereblon, a substrate-recognition protein within the E3-ligase ubiquitin complex, in AMPK dysregulation and OA pathogenesis. METHODS: Cereblon expression was examined in human (n = 5) and mouse (n = 10) OA cartilage. The role of cereblon was investigated through its adenoviral overexpression (n = 10) or knockout (KO, n = 15) in the destabilization of the medial meniscus (DMM)-operated mice. The therapeutic potentials of the chemical cereblon degrader, TD-165, and the AMPK activator, metformin, were assessed through intra-articular (IA) injection to mice (n = 15). RESULTS: Immunostaining revealed that cereblon is upregulated in human and mouse OA cartilage. In DMM model mice, cartilage destruction was exacerbated by overexpression of cereblon in mouse joint tissues (OARSI grade; 1.11 [95% CI: 0.50 to 2.75]), but inhibited in global (-2.50 [95% CI: -3.00 to -1.17]) and chondrocyte-specific (-2.17 [95% CI: -3.14 to -1.06]) cereblon KO mice. The inhibitory effects were more pronounced in mice fed a high-fat diet compared to a regular diet. The degradation of cereblon through IA injection of TD-165 inhibited OA cartilage destruction (-2.47 [95% CI: -3.22 to -1.56]). Mechanistically, cereblon exerts its catabolic effects by negatively modulating AMPK activity within chondrocytes. Consistently, activation of AMPK by IA injection of metformin inhibited posttraumatic OA cartilage destruction (-1.20 ([95% CI: -1.89 to -0.45]). CONCLUSIONS: The cereblon-AMPK axis acts as a catabolic regulator of OA pathogenesis and seems to be a promising therapeutic target in animal models of OA.

Protective effect of sinomenine against CCl4-induced acute liver injury through regulation of mitochondrial biogenesis.

Carbon tetrachloride (CCl4)-provoked acute liver injury (ALI) is typified by intensified apoptotic, inflammatory, and oxidative changes besides mitochondrial dysfunction. Sinomenine is an active constituent in the medicinal plant Sinomenium acutum. The main objective of this study was to determine sinomenine-induced hepatoprotection following CCl4 challenge with an emphasis on unraveling the contribution of mitochondrial biogenesis-related factors. To induce ALI, CCl4 was injected i.p. and sinomenine was orally administered at 10, 25, and 50 mg/kg. Serum factors in relation to liver dysfunction were measured in addition to hepatic analysis of apoptotic, mitochondrial biogenesis, oxidative, and inflammatory parameters. Sinomenine pretreatment significantly lowered ALT and AST, MDA, IL-6, apoptosis intensity, and TNF-α and restored mitochondrial biogenesis besides enhancement of SOD, sirtuin-1, and AMPK. Sinomenine also conferred hepatoprotective impact, as was apparent by lower pathologic changes. These effects were accompanied by changes in gene expression for AMPK/sirtuin-1/PGC-1α/PPARγ. The current study showed sinomenine hepatoprotective impact in CCl4-induced ALI that is associated with its regulation of mitochondrial biogenesis and parallel enhancement of AMPK/sirtuin-1.

8-Prenylgenistein Isoflavone in Cheonggukjang Acts as a Novel AMPK Activator Attenuating Hepatic Steatosis by Enhancing the SIRT1-Mediated Pathway.

8-Prenylgenistein (8PG), a genistein derivative, is present in fermented soybeans (Glycine max), including cheonggukjang (CGJ), and exhibits osteoprotective, osteogenic, and antiadipogenic properties. However, the hepatoprotective effects of 8PG and its underlying molecular mechanisms remain largely unexplored. Here, we identified the high binding affinity of 8PG with AMP-activated protein kinase (AMPK) and sirtuin 1 (SIRT1), which acts as a potent AMPK activator that counteracts hepatic steatosis. Notably, 8PG exhibited better pharmacokinetics with greater absorption and higher plasma binding than the positive controls for the target proteins. Moreover, 8PG exerted non-carcinogenic activity in rats and significantly increased AMPK phosphorylation. Compound C, an AMPK inhibitor, did not antagonize 8PG-activated AMPK in HepG2 cells. 8PG significantly attenuated palmitate-induced lipid accumulation and enhanced phosphorylated AMPK and its downstream target, acetyl-CoA carboxylase. Further, 8PG activated nuclear SIRT1 at the protein level, which promoted fatty acid oxidation in palmitate-treated HepG2 cells. Overall, 8PG acts as a potent AMPK activator, further attenuating hepatic steatosis via the SIRT1-mediated pathway and providing new avenues for dietary interventions to treat metabolic dysfunction-associated steatotic liver disease (MASLD).

Astragaloside IV intervenes multi-regulatory cell death forms against doxorubicin-induced cardiotoxicity by regulating AMPKα2 pathway.

The clinical use of doxorubicin has been severely limited by doxorubicin-induced cardiotoxicity (DIC). Its mechanism is extremely complex and involves reactive oxygen species overgeneration, DNA damage, and aberrant inflammatory activity, which also involves multi-regulatory cell death mechanisms, including apoptosis, autophagy, and pyroptosis. These mechanisms overlap and crosstalk, resulting in the poor intervention of DIC injury. Astragaloside IV (Ast) has polybioactivity and mitigates DIC damage; however, the underlying mechanisms remain unknown. This study aimed to investigate whether Ast pretreatment (Ast-pre) could protect the myocardium against DIC damage and the underlying mechanisms. In particular, the relationship between Ast-pre, AMPKα2 activity, autophagy, apoptosis, and pyroptosis was explored. Firstly, DIC injury models were established using neonatal rat cardiomyocytes (NRCMs) and mice. And then the effects of adaptive autophagy, anti-pyroptosis and anti-apoptosis of Ast-pre were detected using multi-relevant indexes in NRCMs. Further, how does Ast-pre in AMPKα2 phosphorylation was explored. Finally, these results were validated by DIC injury in mice. Ast-pre, similar to disulfiram (pyroptosis inhibitor), effectively alleviated the inflammatory response, inhibited oxidative and energy stress, prevented mitochondrial dysfunction, and protected the myocardium resisting DIC damage, as demonstrated using multi-indexes. The protection of Ast-pre to DIC damage was almostly canceled by paclitaxel (pyroptosis inducer), 3-methyladenine (autophagy inhibitor), and pAD/AMPKα2-shRNA or compound C (AMPK inhibitor) to varying degrees. In conclusion, Ast-pre could upregulate and activate AMPKα2, enhance adaptive autophagy, and improve energy metabolism and mitochondrial function, thereby alleviate DIC-induced pyroptosis and apoptosis in NRCMs and mice.

Bergenin inhibits hepatic fat deposition by activating the AMPK signaling pathway, thereby attenuating alcoholic liver disease.

Alcoholic liver disease (ALD) is a prevalent liver condition that arises from prolonged and excessive alcohol intake. Bergenin (BER) is an effective phytotherapeutic agent that exhibits pharmacological properties, including anti-inflammatory and anti-oxidative effects. To establish an in vivo model of ALD, C57BL/6 mice were continuously fed a high-fat diet (HFD) and administered alcohol gavage for 8 weeks, while concurrently administering BER and evaluated for therapeutic effects. After modeling, the therapeutic effects of BER were evaluated by observing histopathological changes and the detection of relevant biochemical indicators in mice. In addition, RNA sequencing of liver tissues was performed to analyze differentially expressed genes and to investigate the associated signaling pathways in order to elucidate the protective mechanisms of BER. These differentially expressed genes were mainly enriched in lipid metabolism pathways and the cytochrome P450 metabolism of exogenous substances. Subsequently, HepG2 was co-treated with sodium oleate (NaOA) and ethanol to establish an in vitro model, and the specific mechanism by which BER ameliorates ALD was further analyzed in depth. AMPK inhibitor, Compound C (CC), was demonstrated to significantly inhibit the regulation of lipid metabolism by BER in vitro. Finally, the differentially expressed genes selected were validated through qRT-PCR and Western blot analysis. Collectively, our findings revealed that BER effectively alleviated liver injury caused by alcohol and HFD in mice, significantly suppressing lipid deposition in ALD, enhancing alcohol metabolism, and mitigating oxidative stress.

An antifibrotic compound that ameliorates hyperglycaemia and fat accumulation in cell and HFD mouse models.

AIMS/HYPOTHESIS: Appropriate management of blood glucose levels and the prevention of complications are important in the treatment of diabetes. We have previously reported on a compound named HPH-15 that is not only antifibrotic but also AMP-activated protein kinase (AMPK)-activating. In this study, we evaluated whether HPH-15 is useful as a therapeutic medication for diabetes. METHODS: We examined the effects of HPH-15 on AMPK activation, glucose uptake, fat accumulation and lactic acid production in L6-GLUT4, HepG2 and 3T3-L1 cells, as a model of muscle, liver and fat tissue, respectively. Additionally, we investigated the glucose-lowering, fat-accumulation-suppressing, antifibrotic and AMPK-activating effect of HPH-15 in mice fed a high-fat diet (HFD). RESULTS: HPH-15 at a concentration of 10 µmol/l increased AMPK activation, glucose uptake and membrane translocation of GLUT4 in each cell model to the same extent as metformin at 2 mmol/l. The production of lactic acid (which causes lactic acidosis) in HPH-15-treated cells was equal to or less than that observed in metformin-treated cells. In HFD-fed mice, HPH-15 lowered blood glucose from 11.1±0.3 mmol/l to 8.2±0.4 mmol/l (10 mg/kg) and 7.9±0.4 mmol/l (100 mg/kg) and improved insulin resistance. The HPH-15 (10 mg/kg) group showed the same level of AMPK activation as the metformin (300 mg/kg) group in all organs. The HPH-15-treated HFD-fed mice also showed suppression of fat accumulation and fibrosis in the liver and fat tissue; these effects were more significant than those obtained with metformin. Mice treated with high doses of HPH-15 also exhibited a 44% reduction in subcutaneous fat. CONCLUSIONS/INTERPRETATION: HPH-15 activated AMPK at lower concentrations than metformin in vitro and in vivo and improved blood glucose levels and insulin resistance in vivo. In addition, HPH-15 was more effective than metformin at ameliorating fatty liver and adipocyte hypertrophy in HFD-fed mice. HPH-15 could be effective in preventing fatty liver, a common complication in diabetic individuals. Additionally, in contrast to metformin, high doses of HPH-15 reduced subcutaneous fat in HFD-fed mice. Presumably, HPH-15 has a stronger inhibitory effect on fat accumulation and fibrosis than metformin, accounting for the reduction of subcutaneous fat. Therefore, HPH-15 is potentially a glucose-lowering medication that can lower blood glucose, inhibit fat accumulation and ameliorate liver fibrosis.

Heightened TPD52 linked to metabolic dysfunction and associated abnormalities in zebrafish.

The tumor protein D52 (TPD52) gene encodes a proto-oncogene protein associated with various medical conditions, including breast and prostate cancers. It plays a role in multiple biological pathways such as cell growth, differentiation, and apoptosis. The function of TPD52 in lipid droplet biosynthesis has been investigated in vitro. However, its precise role in lipid metabolism in animal models is not fully understood. To investigate the functions of TPD52 in vivo, we performed a conditional TPD52 protein expression analysis using a Tet-off transgenic system to establish conditionally expressed Tpd52 transgenic zebrafish. The effect of Tpd52 on lipogenesis was assessed using various methods, including whole-mount Oil Red O staining, histological examination, and measurement of inflammatory markers and potential targets using real-time quantitative polymerase chain reaction and immunoblotting in Tpd52 fish. Zebrafish with increased Tpd52 levels exhibited notable weight gain and the enlargement of fat deposits, which were mainly attributed to an increase in the volume of adipocytes. Moreover, Tpd52 overexpression was correlated with the triggering of the adipocyte differentiation signaling pathway. During adipocytic differentiation in response to nutrient status, our observations revealed adipogenesis, nonalcoholic fatty liver disease, and metabolic cardiomyopathy (MCM) in Tpd52 transgenic zebrafish. To gain a deeper understanding of the contribution of these proteins to the regulation of cellular growth, we investigated the expression of their corresponding genes and proteins in zebrafish. In the present study, the activated protein kinase pathway was identified as the primary target of TPD52. Adult Tpd52 zebrafish showed increased lipid accumulation, resulting in the development of visceral obesity, nonalcoholic fatty liver disease, and MCM. These findings strongly suggest that TPD52 actively contributes to adipose tissue expansion and its subsequent effects. This investigation provides compelling evidence that Tpd52 facilitates adipocyte development and related metabolic comorbidities in zebrafish.

Adiponectin receptor 1 regulates endometrial receptivity via the adenosine monophosphate­activated protein kinase/E­cadherin pathway.

Endometrial receptivity is essential for successful embryo implantation and pregnancy initiation and is regulated via various signaling pathways. Adiponectin, an important adipokine, may be a potential regulator of reproductive system functions. The aim of the present study was to elucidate the regulatory role of adiponectin receptor 1 (ADIPOR1) in endometrial receptivity. The endometrial receptivity between RL95­2 and AN3CA cell lines was confirmed using an in vitro JAr spheroid attachment model. 293T cells were transfected with control or short hairpin (sh)ADIPOR1 vectors and RL95­2 cells were transduced with lentiviral particles targeting ADIPOR1. Reverse transcription­quantitative PCR and immunoblot assays were also performed. ADIPOR1 was consistently upregulated in the endometrium during the mid­secretory phase compared with that in the proliferative phase and in receptive RL95­2 cells compared with that in non­receptive AN3CA cells. Stable cell lines with diminished ADIPOR1 expression caused by shRNA showed reduced E­cadherin expression and attenuated in vitro endometrial receptivity. ADIPOR1 regulated AMP­activated protein kinase (AMPK) activity in endometrial epithelial cells. Regulation of AMPK activity via dorsomorphin and 5­aminoimidazole­4­carboxamide ribonucleotide affected E­cadherin expression and in vitro endometrial receptivity. The ADIPOR1/AMPK/E­cadherin axis is vital to endometrial receptivity. These findings can help improve fertility treatments and outcomes.

AMPK: The energy sensor at the crossroads of aging and cancer.

AMP-activated protein kinase (AMPK) is a protein kinase that plays versatile roles in response to a variety of physiological stresses, including glucose deprivation, hypoxia, and ischemia. As a kinase with pleiotropic functions, it plays a complex role in tumor progression, exhibiting both tumor-promoting and tumor-suppressing activities. On one hand, AMPK enhances cancer cell proliferation and survival, promotes cancer metastasis, and impairs anti-tumor immunity. On the other hand, AMPK inhibits cancer cell growth and survival and stimulates immune responses in a context-dependent manner. Apart from these functions, AMPK plays a key role in orchestrating aging and aging-related disorders, including cardiovascular diseases (CVD), Osteoarthritis (OA), and Diabetes. In this review article, we summarized the functions of AMPK pathway based on its oncogenic and tumor-suppressive roles and highlighted the importance of AMPK pathway in regulating cellular aging. We also spotlighted the significant role of various signaling pathways, activators, and inhibitors of AMPK in serving as therapeutic strategies for anti-cancer and anti-aging therapy.