Monophosphate-activated Protein Kinase Signaling Research Articles

Silymarin in combination with chlorogenic acid protects against hepatotoxicity induced by doxorubicin in rats: possible role of adenosine monophosphate-activated protein kinase pathway.

Many xenobiotics are known to cause hepatic damage with subsequent significant morbidity and mortality. Doxorubicin (DOX) is a broad-spectrum antineoplastic agent. DOX is reported to cause hepatocellular damage. Previous studies verified the promising role of many natural antioxidant products against various models of hepatic dysfunction. We conducted this study to evaluate the possible hepatoprotective effect of silymarin (SILY) and/or chlorogenic acid (CGA) in a rat model of DOX-induced hepatotoxicity. For this purpose, we randomly divided 30 adult male rats into five equal groups as control, DOX, co-treated DOX with SILY, co-treated DOX with GCA and co-treated DOX with SILY and CGA groups. All treatments were administered every second day for 4 weeks. Our results showed that simultaneous SILY and CGA administration caused a significant decrease in hepatic apoptosis biomarkers (hepatic caspase-3 and nuclear factor-κB levels), a significant improvement in hepatic oxidant/antioxidant status (malondialdehyde and superoxide dismutase) and significant decrease in hepatic pro-inflammatory biomarkers (tumor necrosis factor-alpha and interlukin-1β) compared with DOX treatment. We concluded that adding CGA to SILY acts as a hepatoprotective agent against DOX-induced liver injury through inhibiting apoptosis biomarkers, maintaining antioxidant enzyme levels, decreasing pro-inflammatory cytokines as well as regulating liver adenosine monophosphate-activated protein kinase signaling.

SOD3 deficiency induces liver fibrosis by promoting hepatic stellate cell activation and epithelial-mesenchymal transition.

Hepatic stellate cell (HSC) activation plays an important role in the pathogenesis of liver fibrosis, and epithelial-mesenchymal transition (EMT) is suggested to potentially promote HSC activation. Superoxide dismutase 3 (SOD3) is an extracellular antioxidant defense against oxidative damage. Here, we found downregulation of SOD3 in a mouse model of liver fibrosis induced by carbon tetrachloride (CCl4 ). SOD3 deficiency induced spontaneous liver injury and fibrosis with increased collagen deposition, and further aggravated CCl4 -induced liver injury in mice. Depletion of SOD3 enhanced HSC activation marked by increased α-smooth muscle actin and subsequent collagen synthesis primarily collagen type I in vivo, and promoted transforming growth factor-β1 (TGF-β1)-induced HSC activation in vitro. SOD3 deficiency accelerated EMT process in the liver and TGF-β1-induced EMT of AML12 hepatocytes, as evidenced by loss of E-cadherin and gain of N-cadherin and vimentin. Notably, SOD3 expression and its pro-fibrogenic effect were positively associated with sirtuin 1 (SIRT1) expression. SOD3 deficiency inhibited adenosine monophosphate-activated protein kinase (AMPK) signaling to downregulate SIRT1 expression and thus involving in liver fibrosis. Enforced expression of SIRT1 inhibited SOD3 deficiency-induced HSC activation and EMT, whereas depletion of SIRT1 counteracted the inhibitory effect of SOD3 in vitro. These findings demonstrate that SOD3 deficiency contributes to liver fibrogenesis by promoting HSC activation and EMT process, and suggest a possibility that SOD3 may function through modulating SIRT1 via the AMPK pathway in liver fibrosis.

Therapeutic effects of herbal formula Huangqisan on metabolic disorders via SREBF1, SCD1 and AMPK signaling pathway

ObjectiveMetabolic syndrome is a complex medical condition that has become an alarming epidemic, but an effective therapy for this disease is still lacking. The use of the herbal formula Huangqisan (HQS) to treat diabetes is documented in the Chinese medical literature as early as 1117 A.D.; however, its therapeutic effects and underlying mechanisms remain elusive. MethodsTo investigate the beneficial effects of HQS on metabolic disorders, high-fat diet-induced obesity (DIO), leptin receptor dysfunction (db/db) and low-density lipoprotein receptor-knockout (LDLR−/−) mice were used. Obese mice were treated with either HQS or vehicle. Blood, liver tissue, white fat tissue and brown adipose tissue were harvested at the end of the treatment. Metabolic disease-related parameters were evaluated to test effects of HQS against diabetes, obesity and hyperlipidemia. Aortic arches from LDLR−/− mice were analyzed to investigate the effects of HQS on atherosclerosis. RNA-sequence, quantitative real-time polymerase chain reaction and Western blot were performed to investigate the mechanisms of HQS against metabolic disorder. ResultsHQS lowered body weight, fasting blood glucose and serum lipid levels and improved glucose tolerance and insulin sensitivity in DIO mice and db/db mice (P < 0.05). HQS also blocked atherosclerotic plaque formation in LDLR−/− mice. HQS suppressed de novo lipid synthesis by reducing the expression of messenger RNA for sterol regulatory element-binding factor 1, stearyl coenzyme A desaturase 1 and fatty acid synthase, and enhancing adenosine 5′-monophosphate-activated protein kinase signaling in both in vivo and in vitro experiments, indicating potential mechanisms for HQS’s activity against diabetes. ConclusionHQS is effective for reversing metabolic disorder and has the potential to be used as therapy for metabolic syndrome.

The adiponectin agonist, AdipoRon, inhibits steroidogenesis and cell proliferation in human luteinized granulosa cells

During obesity, excess body weight is not only associated with an increased risk of type 2-diabetes, but also several other pathological processes, such as infertility. Adipose tissue is the largest endocrine organ of the body that produces adipokines, including adiponectin. Adiponectin has been reported to control fertility through the hypothalamic–pituitary–gonadal axis, and folliculogenesis in the ovaries. In this study, we focused on a recent adiponectin-like synthetic agonist called AdipoRon, and its action in human luteinized granulosa cells.We demonstrated that AdipoRon activated the adenosine monophosphate-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor alpha (PPAR) signalling pathways in human luteinized granulosa cells. A 25 μM AdipoRon stimulation reduced granulosa cell proliferation by inducing cell cycle arrest in G1, associated with PTEN and p53 pathway activation. In addition, AdipoRon perturbed cell metabolism by decreasing mitochondrial activity and ATP production. In human luteinized granulosa cells, AdipoRon increased phosphodiesterase activity, leading to a drop in cyclic adenosine monophosphate (cAMP) production, aromatase expression and oestrogens secretion.In conclusion, AdipoRon impacted folliculogenesis by altering human luteinized granulosa cell function, via steroid production and cell proliferation. This agonist may have applications for improving ovarian function in metabolic disorders or granulosa cancers.

Bone marrow mesenchymal stem cells inhibit cardiac hypertrophy by enhancing FoxO1 transcription.

Bone marrow-derived mesenchymal stem cells (BMSCs) have therapeutic potential for certain heart diseases. Previous studies have shown that stem cells inhibit cardiac hypertrophy; however, it is necessary to explore the mechanisms underlying this effect. This study aimed to investigate the possible mechanism underlying the inhibitory effect of BMSCs on cardiomyocyte hypertrophy. We induced cardiomyocyte hypertrophy in cultured rat cells through isoproterenol (ISO) treatment with or without BMSC coculture. A microarray was performed to analyze messenger RNA expression in response to ISO treatment and BMSC coculture. Pathway enrichment analysis showed that the expression of differential genes was closely related to the 5'-adenosine monophosphate-activated protein kinase (AMPK) signaling pathway and that the expression of forkhead box O 1 (FoxO1) was significantly increased in the presence of BMSCs. Furthermore, we determined the expression levels of p-AMPK/AMPK and p-FoxO1/FoxO1 by western blot analysis. The expression of p-AMPK/AMPK was upregulated, whereas that of p-FoxO1/FoxO1 was downregulated upon coculturing with BMSCs. The AMPK-specific antagonist Compound C inhibited the downregulation of p-FoxO1/FoxO1 induced by the BMSC coculture. Furthermore, treatment with the specific FoxO1 antagonist AS1842856 reduced the inhibitory effects of BMSCs on cardiomyocyte hypertrophy in vivo and in vitro. Our present study demonstrates the inhibition of cardiomyocyte hypertrophy by BMSCs, which occurs partly through the AMPK-FoxO1 signaling pathway.

Gymnaster Koraiensis Extract Alleviated Metabolic Syndrome Symptoms and Stimulated UCP1-Independent Energy Consumption via AMPK Activation in White Adipose Tissue.

Metabolic syndrome and obesity are rising worldwide concerns that are accompanied by adverse health consequences. Here, it is hypothesized that the ethanol extract from Gymnaster koraiensis (GK), an edible Korean plant known for its anti-cancer and hepatoprotective properties, could attenuate metabolic syndrome-related symptoms in high-fat dietary-induced obese (DIO) mice. Administration of 100mg kg-1 GK extract to DIO mice effectively reduces body and white adipose tissue (WAT) weight. It also reduces cardiovascular disease risk and improves insulin resistance by lowering the fasting blood glucose levels and mitigating oxidative stress and inflammation. Moreover, supplementation with GK causes elevated energy expenditure in WAT by increasing the mitochondrial oxidative capacity and lipid catabolism through upregulated adenosine monophosphate-activated protein kinase (AMPK) signaling. Orlistat is used as a positive control drug due to its widespread use in previous studies. It is found that GK extract causes weight loss, similar to Orlistat, and it additionally shows unique functions, such as upregulation of energy consumption in WAT. GK extract treatment prominently reduces obesity and its associated metabolic complications, such as hyperlipidemia, hyperglycemia, and insulin resistance. Hence, It can be used as a promising multi-target functional food that can improve metabolic syndrome-related symptoms.

STAT1-induced upregulation of lncRNA LINP1 promotes cell proliferation and inhibits apoptosis via AMPK signaling pathway in papillary thyroid cancer.

The purpose of this study was to detect the relative expression of long non-coding ribonucleic acid (lncRNA) in non-homologous end joining pathway 1 (LINP1) in papillary thyroid cancer (PTC) tissues and cells, and to investigate the molecular mechanisms of abnormal expression and biological function of LINP1. The relative expression of LINP1 in PTC tissues and cells was detected via quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR), and the impact of small interfering (si)-LINP1 on the proliferative capacity of PTC cells was studied using Cell Counting Kit-8 (CCK-8) and colony formation assays. After the expression of LINP1 in PTC cells was interfered, flow cytometry was applied to determine the changes in cell cycle distribution and apoptosis rate. The transcription factors binding to the promoter region of LINP1 were predicted by bioinformatics. Next, qRT-PCR assay was adopted to measure the changes in LINP1 expression after interference in the expression of signal transducer and activator of transcription 1 (STAT1). Finally, the changes in the expressions of molecular markers of the adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling pathway were examined via Western blotting assay after the expressions of STAT1 and LINP1 were interfered. It was shown in qRT-PCR results that LINP1 expression was upregulated in 42 out of 53 cases of PTC tissues and in all PTC cells. After interference in the expression of LINP1 in PTC cells, the results of CCK-8 and colony formation assays indicated that the proliferative capacity of the cells was repressed. According to the results of flow cytometry, the cell cycle was arrested at the G1/G0 phase, and the apoptosis rate was increased. In addition, the bioinformatics predicted that STAT1 could bind to the promoter region of LINP1, and the results of qRT-PCR indicated that the expression of LINP1 declined after STAT1 expression was interfered. Moreover, it was indicated in the Western blotting assay after interference in the expressions of STAT1 and LINP1 that the expression of molecular marker (Phosphorylation AMPK, p-AMPK) of the AMPK signaling pathway was altered but the expression of total AMPK did not change. The transcription factor STAT1 promotes the expression of LINP1 in PTC, and highly expressed LINP1 facilitates the proliferation and inhibits the apoptosis of PTC by suppressing the AMPK signaling pathway.

Metformin and cancer immunity

The immune system plays an essential and central role in tumor cell differentiation, proliferation, angiogenesis, apoptosis, invasion, and metastasis. Over the past decade, cancer therapy has rapidly evolved from traditional approaches, such as surgery, chemotherapy, and radiotherapy, to revolutionary new treatment options with immunotherapy. This new era of cancer treatment options has now been clinically tested and applied to many forms of human malignancies, often with quite dramatic results. As we develop more effective combinations of cancer treatment, several agents have been recently investigated, putatively identified as anticancer agents, or immunostimulatory molecules. One such agent is metformin, originally developed as a fairly standard first-line therapy for patients with type-2 diabetes mellitus (T2DM). Given the underlying mechanisms of action, researchers began to examine the alternative functions and possible utility of metformin, finding that the cancer risk in patients with T2DM was reduced. It appears that metformin, at least in part, has an antitumor effect through activation of the 5' adenosine monophosphate-activated protein kinase (AMPK) signaling pathway. Moreover, numerous studies have demonstrated that metformin interferes with key immunopathological mechanisms that are involved in the pathological processes or associated with malignant progression. Such insights may shed light on further analyzing whether metformin enhances the effectiveness of the immunotherapy and overcomes the immunotherapy resistance in the patients. Herein, we provide a comprehensive review of the literature examining the impact of metformin upon the host immune system and cancer immunity.

Mitigation of Microglia-mediated Acute Neuroinflammation and Tissue Damage by Heme Oxygenase 1 in a Rat Spinal Cord Injury Model

Acute neuroinflammation is the major detrimental factor that causes secondary tissue damage after spinal cord injury (SCI). Curbing neuroinflammation would reduce the neuronal death and benefit functional recovery. In the current study, we used a HO-1-encoding lentivirus to transduce microglia, and adoptively transferred these microglia into injured rat spinal cords. Lentivirus-induced overexpression of exogenous HO-1 significantly inhibited microglia-mediated inflammatory response after SCI, as demonstrated by lower expression of pro-inflammatory mediators in transferred microglia. In addition, the overall post-SCI neuroinflammation was also suppressed by HO-1-overexpressing microglia, as indicated by less leukocyte infiltration and lower pro-inflammatory cytokine production in the spinal cord. Consistently, the tissue damage and neuronal apoptosis were decreased in injured spinal cords, while the locomotor function was moderately improved. We further identified that adenosine 5′-monophosphate-activated protein kinase (AMPK) signaling was involved in the regulatory effect of HO-1 on microglia, because HO-1 overexpression increased the activating phosphorylation of AMPKα. Moreover, the AMPK inhibitor compound C diminished the anti-inflammatory effect of HO-1 in lipopolysaccharide-stimulated microglia in vitro. Taken together, we proved that microglial HO-1 reduced acute post-SCI neuroinflammation. Our study might provide a promising therapeutic approach to benefit SCI recovery.

In Vivo Antifatigue Activity of Spirulina Peptides Achieved by Their Antioxidant Activity and by Acting on Fat Metabolism Pathway in Mice

Spirulina are multicellular and filamentous cyanobacteria that have achieved considerable popularity in the health sector, food industry, and aquaculture. In the present study, we aimed to evaluate the antifatigue effects of Spirulina-derived peptides on Institute for Cancer Research mice and explore the association between antifatigue activity and fat metabolism involving the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway. We extracted the peptides from Spirulina by enzymatic hydrolysis and ultrafiltration. The mice were orally administered with Spirulina peptides (0.125, 0.5, and 2 mg/g bw/day) daily for 4 weeks. We found that Spirulina peptides, especially the high-dose group, significantly prolonged the swimming time by 126.1%, increased the activities of antioxidant enzymes, and decreased the content of malondialdehyde by 60.2% compared with the glutathione (GSH) group. The levels of some indicators of exercise fatigue, including lactic dehydrogenase, blood lactic acid, and creatine phosphokinase, were reduced. In the high-dose group, these indicators were reduced by 40.7%, 22.3%, and 11.3% compared with the GSH group. Spirulina peptides did not excessively consume blood sugar or glycogen in the liver and muscle to produce energy. However, the triglyceride level was reduced, and the level of free fatty acids was increased. Besides, the proteins in the AMPK signaling pathway were activated. Taken together, these findings indicated that Spirulina peptides could effectively alleviate physical fatigue by reducing the production of lactic acid and improving antioxidant capacity. Spirulina peptides also helped increase the energy resources by activating the AMPK signaling pathway to utilize fat metabolism.

The Study of the Response of Fat Metabolism to Long-Term Energy Stress Based on Serum, Fatty Acid and Transcriptome Profiles in Yaks.

Simple SummaryThe serum, fatty acid and transcriptome profiles in the subcutaneous fat of yaks were measured to explore the effect of long-term energy stress (ES) on fat metabolism during the cold season. The study indicated that under long-term ES during the cold season, the amount of fat in yaks was less, and fat mobilization was one of the main ways by which energy was obtained in yaks. Yaks regulated fat metabolism in subcutaneous fat primarily through adenosine 5′-monophosphate-activated protein kinase (AMPK) signaling. Glucose (GLU) intake, fat catabolism, fatty acid synthesis and fatty acid oxidation in the subcutaneous fat of yaks were all inhibited, which resulted in the fat mobilization of yaks slowing as much as possible under long-term ES. In addition, the energy expenditures in fat cells were inhibited by regulating phosphatidylinositol 3’ -kinase (PI3K)-serine/threonine-protein kinase (Akt) andmammalian target of rapamycin (mTOR) signaling, and the limited energy obtained from GLU and fat was consumed by muscle and organs as much as possible. These factors led to an energy balance in yaks under long-term ES. The fat stored in yaks can be expended for as long as possible, and yaks can survive for as long as necessary under long-term ES.Long-term energy stress (ES) during the cold season is a serious problem for the breeding of yaks. In this paper, the response of fat metabolism in yaks to long-term ES during the cold season was studied. Gas chromatography (GC) analysis showed that the percentage of saturated fatty acids (SFAs) in the subcutaneous fat of the yaks in the ES group was 42.7%, which was less than the 56.6% in the CO group (p < 0.01) and the percentage of polyunsaturated unsaturated fatty acids (PUFAs) in the subcutaneous fat of the yaks in the ES group was 38.3%, which was more than the 26.0% in the CO group (p < 0.01). The serum analysis showed that fatty acid oxidation in yaks was increased under long-term ES. In the subcutaneous fat of yaks under long-term ES, the gene expression levels of glycerol-3-phosphate acyltransferase 4 (GPAT4), hormone-sensitive lipase (HSL), patatin-like phospholipase domain-containing protein 2 (PNPLA2), acyl-CoA dehydrogenase (ACAD), acyl-coenzyme A thioesterase 8 (ACOT8), facilitated glucose transporter (GLUT4), 3-oxoacyl-[acyl-carrier-protein] synthase (OXSM), oestradiol 17-beta-dehydrogenase 8 (HSD17B8) and malonate-Co-A ligase ACSF3 (ACSF3) were downregulated (q < 0.05), whereas the gene expression levels of aquaporin-7 (AQP7), long-chain-fatty-acid-CoA ligase (ACSL), elongation of very long chain fatty acids protein (ELOVL) and fatty acid desaturase 1 (FADS1) were upregulated (q < 0.05), indicating the inhibition of fat catabolism, fat anabolism, fatty acid oxidation, glucose (GLU) intake and SFA synthesis and the promotion of glycerinum (GLY) transportation and PUFA synthesis. Additional findings showed that the gene expression levels of leptin (LEP), adenosine 5′-monophosphate-activated protein kinase (AMPK) and phosphatidylinositol 3-kinase (PI3K) were upregulated (q < 0.05), whereas the gene expression levels of malonyl-CoA decarboxylase (MCD), sterol regulatory element-binding protein 1 (SREBF1), mammalian target of rapamycin (mTOR) and serine/threonine-protein kinase (AKT) were downregulated (q < 0.05), indicating that fat metabolism in the subcutaneous fat of yaks under ES was mainly regulated by AMPK signaling and mTOR and PI3K-AKT signaling were also involved. Energy consumption was inhibited in the subcutaneous fat itself. This study can provide a theoretical basis for the healthy breeding and genetic breeding of yaks.

\u03c9-6 Polyunsaturated fatty acids (linoleic acid) activate both autophagy and antioxidation in a synergistic feedback loop via TOR-dependent and TOR-independent signaling pathways

ω-6 Polyunsaturated fatty acids (PUFAs) are essential fatty acids that participate in macroautophagy (hereafter referred to as autophagy) and the Kelch ECH-associating protein 1 (Keap1)—nuclear factor erythroid 2-related factor 2 (Nrf2) antioxidant system in organisms. However, the molecular mechanisms by which ω-6 PUFAs (linoleic acid) regulate autophagy and Keap1–Nrf2 antioxidant system are not completely understood. Therefore, the purposes of this study were to explore the molecular mechanisms by which ω-6 PUFAs (linoleic acid) regulate autophagy and antioxidant system and to investigate the potential relationship between autophagy and antioxidant system through transcriptomic analysis, quantitative real-time polymerase chain reaction (RT-qPCR), western blot analysis, coimmunoprecipitation (Co-IP) and electrophoretic mobility shift assays (EMSAs) in vivo and in vitro. The results of the present study indicated that ω-6 PUFAs in diets induced autophagy but decrease antioxidant ability in vivo. However, the results also provided evidence, for the first time, that ω-6 PUFAs (linoleic acid) induced autophagy and increased antioxidant ability through the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway and the AMPK-target of rapamycin (TOR) signaling pathway in hepatocytes in vitro. Interestingly, the findings revealed a ω-6 PUFA-induced synergistic feedback loop between autophagy and antioxidant system, which are connected with each other through the P62 and Keap1 complex. These results suggested that ω-6 PUFAs (linoleic acid) could be useful for activating a synergistic feedback loop between autophagy and antioxidant system and could greatly aid in the prevention and treatment of multiple pathologies.

Effects of dietary corticosterone on the central adenosine monophosphate-activated protein kinase (AMPK) signaling pathway in broiler chickens.

Glucocorticoids (GCs) induce the activation of the central adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling pathway in birds. In this study, we aimed to investigate the effects of corticosterone (CORT) supplemented in diet on the central AMPK signaling pathway in broilers. The average daily gain was reduced by CORT treatment, and the average daily feed intake remained unchanged. Plasma glucose, triglyceride, total cholesterol, and CORT contents were increased by CORT administration. In addition, CORT treatment decreased the relative weights of heart, spleen, and bursa and increased the relative weights of liver and abdominal fat. The glycogen contents in the liver and breast muscle were higher in the chicks treated with CORT. CORT treatment upregulated the gene expression of mammalian target of rapamycin, glucocorticoid receptor, AMPKα2, neuropeptide Y(NPY), liver kinase B1 (LKB1), AMPKα1, and fatty acid synthase in the hypothalamus. Moreover, CORT treatment increased the protein levels of acetyl-coenzyme A carboxylase (ACC) phosphorylation and total AMPK and phosphorylated AMPK in the hypothalamus. Hence, CORT administration in the diet activated the LKB1-AMPK-NPY/ACC signaling pathway in the hypothalamus of broiler.

HIF-1α Mediates Osteoclast-Induced Mandibular Condyle Growth via AMPK Signaling

During the mandibular condylar growth, the absorption of calcified cartilage matrix induced by osteoclasts is crucial for the continuous endochondral osteogenesis. Meanwhile, recent studies showed that subchondral bone resided within the low-oxygen microenvironment, and our previous study revealed that hypoxia-inducible transcription factor 1α (HIF-1α) promoted osteoclastogenesis under hypoxia. However, whether HIF-1α regulates the function of osteoclasts in the mandibular condyle cartilage remains elusive. Our study indicated that severe deformity of the mandibular condyle was displayed in 10-wk-old osteoclast-specific HIF-1α conditional knockout (CKO) mice, accompanied by shortened length of condylar process and disorganized fibrocartilage. In 1-, 2-, and 4-wk-old CKO mice, the size of the hypertrophic layer and chondrocytic layer was significantly thickened. In the chondrocytic layer, chondrocytes were atrophied, showing a form of apoptosis in 4-wk-old CKO mice. Furthermore, an increase in the thickness of the fibrous and proliferating layer was observed in 10-wk-old CKO mice, as well as a significant decrease in that of the chondrocytic and hypertrophic chondrocyte layers. Interestingly, the articular surface of the condylar process abnormally presented a horizontal concave shape, and a disk-like acellular connective tissue appeared. In addition, genetic ablation of HIF-1α blunted cartilage matrix loss by subchondral osteoclast deficiency, resulting in a high subchondral bone mass phenotype, accompanied with a decreased number of blood vessels, alkaline phosphatase staining, and vascular endothelial growth factor (VEGF) expression. Mechanistically, the number of osteoclasts in the center of the condyle in CKO mice was significantly reduced by attenuated expression of adenosine 5′-monophosphate-activated protein kinase (AMPK) signaling. These findings reveal a novel influence of HIF-1α function in osteoclasts on maintenance of osteoclast-induced resorption of calcified cartilage matrix via AMPK signaling, as well as subchondral bone formation through VEGF-dependent angiogenesis in bone marrow.

Diosmetin alleviates hypoxia‑induced myocardial apoptosis by inducing autophagy through AMPK activation.

Diosmetin has shown great potential in the control of several diseases. The aim of the present study was to evaluate the role of diosmetin as a candidate agent for the treatment of myocardial infarction which was mainly caused by hypoxia. The model of hypoxia-injured myocardial cells was established using the H9c2 cell line. Cell viability was determined using Cell Counting Kit-8, cell apoptosis was determined by Annexin V-FITC Apoptosis Detection Kit and cleaved caspase-3 level was assessed by western blot analysis. Autophagy was monitored using a commercial kit, and a well-established reporter system was used to confirm the role of diosmetin in autophagy. The activity of adenosine 5′-monophosphate-activated protein kinase (AMPK) signaling was detected by western blot analysis. Cell viability assay indicated that diosmetin alleviated hypoxia-induced cell death of H9c2 cells in a dose-dependent manner. Data of the apoptosis assay revealed that diosmetin reduced the proportion of apoptotic cells in the hypoxia-injured H9c2 cells. It was also found that the occurrence of autophagy was promoted when hypoxia-injured cells were treated with diosmetin alone, and results of the western blot analysis revealed that AMPK signaling was activated by diosmetin. Administration of diosmetin together with an inhibitor of autophagy (3-methyladenine, 3-MA) or AMPK (Compound C) was able to decrease the diosmetin-induced autophagy as well as the cytoprotective effects in the hypoxia-injured cells. Our study concluded that diosmetin exhibits a cytoprotective effect on hypoxia-injured myocardial cells by inducing autophagy and alleviating apoptosis. AMPK was demonstrated to regulate the observed effects caused by diosmetin. This investigation confirmed diosmetin as a promising drug candidate for myocardial infarction treatment. The present findings regarding the inherent molecular mechanisms involved in the protective effects of diosmetin promote the clinical application of diosmetin.

Geniposide alleviates non-alcohol fatty liver disease via regulating Nrf2/AMPK/mTOR signalling pathways.

Non‐alcohol fatty liver disease (NAFLD) is a common disease which causes serious liver damage. Geniposide (GEN), a kind of iridoid glycoside extracted from Gardenia jasminoides fruit, has many biological effects, such as resistance to cell damage and anti‐neurodegenerative disorder. Lipid accumulation was obvious in tyloxapol‐induced liver and oil acid (OA) with palmitic acid (PA)‐induced HepG2 cells compared with the control groups while GEN improved the increasing conditions. GEN significantly lessened the total cholesterol (TC), the triglyceride (TG), low‐density lipoprotein (LDL), very low‐density lipoprotein (VLDL), myeloperoxidase (MPO), reactive oxygen species (ROS) and increased high‐density lipoprotein (HDL), superoxide dismutase (SOD) to response the oxidative stress via activating nuclear factor erythroid‐2–related factor 2 (Nrf2), haeme oxygenase (HO)‐1 and peroxisome proliferator‐activated receptor (PPAR)α which may influence the phosphorylation of adenosine 5’‐monophosphate–activated protein kinase (AMPK) signalling pathway in mice and cells. Additionally, GEN evidently decreased the contents of sterol regulatory element‐binding proteins (SREBP)‐1c, phosphorylation (P)‐mechanistic target of rapamycin complex (mTORC), P‐S6K, P‐S6 and high mobility group protein (HMGB) 1 via inhibiting the expression of phosphoinositide 3‐kinase (PI3K), and these were totally abrogated in Nrf2−/− mice. Our study firstly proved the protective effect of GEN on lipid accumulation via enhancing the ability of antioxidative stress and anti‐inflammation which were mostly depend on up‐regulating the protein expression of Nrf2/HO‐1 and AMPK signalling pathways, thereby suppressed the phosphorylation of mTORC and its related protein.

Interplay of adenosine monophosphate-activated protein kinase/sirtuin-1 activation and sodium influx inhibition mediates the renal benefits of sodium-glucose co-transporter-2 inhibitors in type 2 diabetes: A novel conceptual framework.

Long-term treatment with sodium-glucose co-transporter-2 (SGLT2) inhibitors slows the deterioration of renal function in patients with diabetes. This benefit cannot be ascribed to an action on blood glucose, ketone utilization, uric acid or systolic blood pressure. SGLT2 inhibitors produce a striking amelioration of glomerular hyperfiltration. Although initially ascribed to an action of these drugs to inhibit proximal tubular glucose reabsorption, SGLT2 inhibitors exert renoprotective effects, even in patients with meaningfully impaired levels of glomerular function that are sufficient to abolish their glycosuric actions. Instead, the reduction in intraglomerular pressures may be related to an action of SGLT2 inhibitors to interfere with the activity of sodium-hydrogen exchanger isoform 3, thereby inhibiting proximal tubular sodium reabsorption and promoting tubuloglomerular feedback. Yet, experimentally, such an effect may not be sufficient to prevent renal injury. It is therefore noteworthy that the diabetic kidney exhibits an important defect in adenosine monophosphate-activated protein kinase (AMPK) and sirtuin-1 (SIRT1) signalling, which may contribute to the development of nephropathy. These transcription factors exert direct effects to mute oxidative stress and inflammation, and they also stimulate autophagy, a lysosomally mediated degradative pathway that maintains cellular homeostasis in the kidney. SGLT2 inhibitors induce both AMPK and SIRT1, and they have been shown to stimulate autophagy, thereby ameliorating cellular stress and glomerular and tubular injury. Enhanced AMPK/SIRT1 signalling may also contribute to the action of SGLT2 inhibitors to interfere with sodium transport mechanisms. The dual effects of SGLT2 inhibitors on AMPK/SIRT1 activation and renal tubular sodium transport may explain the protective effects of these drugs on the kidney in type 2 diabetes.

Irisin induces trophoblast differentiation via AMPK activation in the human placenta.

Irisin, an adipokine, regulates differentiation and phenotype in various cell types including myocytes, adipocytes, and osteoblasts. Circulating irisin concentration increases throughout human pregnancy. In pregnancy disorders such as preeclampsia and gestational diabetes mellitus, circulating irisin levels are reduced compared to healthy controls. To date, there are no data on the role and molecular function of irisin in the human placenta or its contribution to pathophysiology. Aberrant trophoblast differentiation is involved in the pathophysiology of preeclampsia. The current study aimed to assess the molecular effects of irisin on trophoblast differentiation and function. First-trimester placental explants were cultured and treated with low (10 nM) and high (50 nM) physiological doses of irisin. Treatment with irisin dose-dependently increased both in vitro placental outgrowth (on Matrigel™) and trophoblast cell-cell fusion. Adenosine monophosphate-activated protein kinase (AMPK) signaling, an important regulator of cellular energy homeostasis that is involved in trophoblast differentiation and pathology, was subsequently investigated. Here, irisin exposure induced placental AMPK activation. To determine the effects of irisin on trophoblast differentiation, two trophoblast-like cell lines, HTR-8/SVneo and BeWo, were treated with irisin and/or a specific AMPK inhibitor (Compound C). Irisin-induced AMPK phosphorylation in HTR-8/SVneo cells. Additionally, as part of the differentiation process, integrin switching from α6 to α1 occurred as well as increased invasiveness. Overall, irisin promoted differentiation in villous and extravillous cell-based models via AMPK pathway activation. These findings provide evidence that exposure to irisin promotes differentiation and improves trophoblast functions in the human placenta that are affected in abnormal placentation.

Exosomes from mesenchymal stem cells overexpressing MIF enhance myocardial repair.

Accumulating evidence has shown that mesenchymal stem cell (MSC)-derived exosomes (exo) mediate cardiac repair following myocardial infarction (MI). Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine, plays a critical role in regulating cell homeostasis. This study aimed to investigate the cardioprotective effects of exo secreted from bone marrow-MSCs (BM-MSCs) overexpressing MIF in a rat model of MI. MIF plasmid was transducted in BM-MSCs. Exo were isolated from the supernatants of BM-MSCs and MIF-BM-MSCs, respectively. The morphology of mitochondria in neonatal mice cardiomyocytes (NRCMs) was determined by MitoTracker staining. The apoptosis of NRCMs was examined by deoxynucleotidyl transferase-mediated dUTP nick end-labeling. BM-MSC-exo and MIF-BM-MSC-exo were intramuscularly injected into the peri-infarct region in a rat model of MI. The heart function of rats was assessed by echocardiography. The expression of MIF was greatly enhanced in MIF-BM-MSCs compared with BM-MSCs. Both BM-MSC-exo and MIF-BM-MSC-exo expressed CD63 and CD81. NRCMs treated with MIF-BM-MSC-exo exhibited less mitochondrial fragmentation and cell apoptosis under hypoxia/serum deprivation (H/SD) challenge than those treated with BM-MSC-exo via activating adenosine 5'-monophosphate-activated protein kinase signaling. Moreover, these effects were partially abrogated by Compound C. Injection of BM-MSC-exo or MIF-BM-MSC-exo greatly restored heart function in a rat model of MI. Compared with BM-MSC-exo, injection of MIF-BM-MSC-exo was associated with enhanced heart function, reduced heart remodeling, less cardiomyocyte mitochondrial fragmentation, reactive oxygen species generation, and apoptosis. Our study reveals a new mechanism of MIF-BM-MSC-exo-based therapy for MI and provides a novel strategy for cardiovascular disease treatment.

Interactions between metabolism regulator adiponectin and intrinsic cardiac autonomic nervous system: A potential treatment target for atrial fibrillation

BackgroundPrevious studies indicated that inhibiting the cardiac autonomic nervous system (CANS) suppressed atrial fibrillation (AF). Clinical research revealed serum adiponectin (APN) exerted a beneficial influence on sympathetic and vagal tone in patients with type 2 diabetes. However, the effects of APN on CANS is unknown. This study aims to investigate whether APN could regulate CANS and suppress rapid atrial pacing (RAP)-induced AF. MethodsEighteen beagles were divided into the control group (saline plus sham RAP, N = 6), the RAP group (saline plus RAP, N = 6) and the APN + RAP group (APN plus RAP, N = 6). APN (10 μg, 0.1 μg/μL) or saline was microinjected into 4 major ganglionated plexi (GP) prior to RAP. Atrial electrophysiological parameters, anterior right GP (ARGP) function, neural activity and GP tissues were detected. ResultsCompared with the control treatment, RAP shortened effective refractory period (ERP) values at all sites and increased cumulative window of vulnerability (ΣWOV), ARGP function and neural activity, whereas APN injection reversed these changes. Mechanistically, APN ameliorated RAP-induced inflammatory response and down-regulated the expression of c-fos protein and nerve growth factor. Moreover, the APN receptors 1 and APN receptors 2 were detected both in neurons and in non-neuronal cells. APN pretreatment activated downstream adenosine monophosphate-activated protein kinase (AMPK) signaling, inhibited nuclear factor-kappa B signaling and promoted macrophage phenotype switching from proinflammatory to anti-inflammatory state. ConclusionsThis study demonstrates that administration of APN into GP can suppress RAP-induced AF by regulating the CANS. APN signaling may provide a potential therapeutic target to AF.