bims-amsmem 2022-06-05 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2022–06–05
nineteen papers selected by
Dipsikha Biswas, Københavns Universitet

SRC plays a specific role in the cross-talk between apoptosis and autophagy via phosphorylation of a novel regulatory site on AMPK.
PFKP alleviates glucose starvation-induced metabolic stress in lung cancer cells via AMPK-ACC2 dependent fatty acid oxidation.
Inhibitors of IFN gene stimulators (STING) improve intestinal ischemia-reperfusion-induced acute lung injury by activating AMPK signaling.
Polydatin, A Glycoside of Resveratrol, Is Better Than Resveratrol in Alleviating Non-alcoholic Fatty Liver Disease in Mice Fed a High-Fructose Diet.
Amentoflavone promotes ferroptosis by regulating reactive oxygen species (ROS) /5'AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) to inhibit the malignant progression of endometrial carcinoma cells.
Genistein accelerates glucose catabolism via activation the GPER-mediated cAMP/PKA-AMPK signaling pathway in broiler chickens.
Liver PP2A-Cα protects from parenteral nutrition-associated hepatic steatosis.
Obesity induces adipose fibrosis and collagen cross-linking through suppressing AMPK and enhancing lysyl oxidase expression.
Bone morphogenetic protein signaling regulation of AMPK and PI3K in lung cancer cells and C. elegans.
Effect of alpha-mangostin on olanzapine-induced metabolic disorders in rats.
Agomelatine, a structural analog of melatonin, improves kidney dysfunction through regulating the AMPK/mTOR signaling pathway to promote autophagy in obese rats.
Hepatocyte-derived MANF mitigates ethanol-induced liver steatosis in mice via enhancing ASS1 activity and activating AMPK pathway.
Renal protection induced by physical exercise may be mediated by the irisin/AMPK axis in diabetic nephropathy.
Mitochondrial phosphatidylethanolamine synthesis affects mitochondrial energy metabolism and quiescence entry through attenuation of Snf1/AMPK signaling in yeast.
Muscle satellite cells are impaired in type 2 diabetic mice by elevated extracellular adenosine.
GLP-1 regulates exercise endurance and skeletal muscle remodeling via GLP-1R/AMPK pathway.
Selective transportation and energy homeostasis regulation of dietary advanced glycation end-products in human intestinal Caco-2 cells.
Platelet-rich plasma contributes to chondroprotection by repairing mitochondrial function via AMPK/NF-κB signaling in osteoarthritic chondrocytes.
TRIM22 inhibits osteosarcoma progression through destabilizing NRF2 and thus activation of ROS/AMPK/mTOR/autophagy signaling.

Autophagy Rep. 2022 ;1(1): 38-41

SRC plays a specific role in the cross-talk between apoptosis and autophagy via phosphorylation of a novel regulatory site on AMPK.

Ming Zhao, Darren Finlay, Robert Liddington, Kristiina Vuori.

  Cell detachment from the extracellular matrix (ECM) typically promotes cell death via a form of apoptosis known as anoikis. However, in tumor cells, detachment can also induce cell survival, utilizing a process known as macroautophagy/autophagy, which involves degradation and removal of apoptotic proteins as well as rewiring of metabolic pathways so that cells can survive under stress. The crosstalk between the competing processes of anoikis and autophagy is only partially understood but may be critical for the design of multi-drug therapeutic strategies. Here, we summarize our recent studies, which reveal a direct regulatory link between a major mediator of cell survival in adherent cells, the ECM-integrin-activated dual tyrosine kinase complex of SRC and PTK2/FAK, and a major regulator of cell metabolism and autophagy, AMP-activated protein kinase (AMPK). We identify a novel SRC phosphorylation site on AMPK and demonstrate that this phosphorylation event plays key roles in AMPK regulation, autophagy induction, and cell survival.

Keywords:  AMPK; PTK2/FAK; SRC; apoptosis; autophagy; cell attachment; cell detachment; phosphorylation

DOI:  https://doi.org/10.1080/27694127.2022.2047266
Cell Discov. 2022 May 31. 8(1): 52

PFKP alleviates glucose starvation-induced metabolic stress in lung cancer cells via AMPK-ACC2 dependent fatty acid oxidation.

Jiaqing Chen, Li Zou, Guang Lu, Oleg Grinchuk, Lei Fang, Derrick Sek Tong Ong, Reshma Taneja, Choon-Nam Ong, Han-Ming Shen.

Cancer cells adopt metabolic reprogramming to promote cell survival under metabolic stress. A key regulator of cell metabolism is AMP-activated protein kinase (AMPK) which promotes catabolism while suppresses anabolism. However, the underlying mechanism of AMPK in handling metabolic stress in cancer remains to be fully understood. In this study, by performing a proteomics screening of AMPK-interacting proteins in non-small-cell lung cancer (NSCLC) cells, we discovered the platelet isoform of phosphofructokinase 1 (PFKP), a rate-limiting enzyme in glycolysis. Moreover, PFKP was found to be highly expressed in NSCLC patients associated with poor survival. We demonstrated that the interaction of PFKP and AMPK was greatly enhanced upon glucose starvation, a process regulated by PFKP-associated metabolites. Notably, the PFKP-AMPK interaction promoted mitochondrial recruitment of AMPK which subsequently phosphorylated acetyl-CoA carboxylase 2 (ACC2) to enhance long-chain fatty acid oxidation, a process helping maintenance of the energy and redox homeostasis and eventually promoting cancer cell survival under glucose starvation. Collectively, we revealed a critical non-glycolysis-related function of PFKP in regulating long-chain fatty acid oxidation via AMPK to alleviate glucose starvation-induced metabolic stress in NSCLC cells.

DOI: https://doi.org/10.1038/s41421-022-00406-1
Eur J Med Res. 2022 May 31. 27(1): 79

Inhibitors of IFN gene stimulators (STING) improve intestinal ischemia-reperfusion-induced acute lung injury by activating AMPK signaling.

Mei Yang, Yu-Xia Ma, Ying Zhi, Hai-Bin Wang, Li Zhao, Peng-Sheng Wang, Jie-Ting Niu.

   BACKGROUND: Acute lung injury (ALI) caused by intestinal ischemia-reperfusion is a life-threatening disease. Interferon gene stimulator (STING) is a cytoplasmic DNA sensor that participates in the initiation of the inflammatory response. This study aims to establish whether C-176 (STING inhibitor) improves ALI under intestinal ischemia-reperfusion conditions.
METHODS: To induce ALI, 72 male C57BL/6 mice were subjected to intestinal ischemia for 60 min and reperfusion for 3 h. Through intraperitoneal injection, C-176, a selective STING inhibitor, was injected 30 min before surgical treatment; meanwhile, compound C, an antagonist of adenosine monophosphate-activated protein kinase (AMPK), was administered 30 min after surgery. Based on immunofluorescence and Western blot assays, post-ALI assessments included lung water content (TLW), bronchoalveolar lavage fluid (BALF) protein, H&E staining, Masson staining, pulmonary pyroptosis [Gasdermin-D (GSDMD), cleaved caspase-1], and apoptosis (TUNEL, cleaved caspase-3).
RESULTS: C-176 administration significantly attenuated intestinal ischemia-reperfusion-mediated ALI; this effect was reflected by exacerbated TLW and BALF protein, aggravated lung injury score, elevated degree of pulmonary fibrosis, increased TUNEL- and GSDMD-positive cells, and upregulated phospho-AMPK, cleaved caspase-1, cleaved caspase-3 and IFNβ mRNA expression. Moreover, C-176 increased phospho-AMPK under ALI conditions. Nonetheless, compound C partially reversed these beneficial effects.
CONCLUSION: C-176, a selective STING inhibitor, improves intestinal ischemia-reperfusion-mediated ALI, and its underlying mechanism may be associated with AMPK signal activation.

Keywords:  AMPK; Acute lung injury; Inflammation; Intestinal ischemia–reperfusion; STING

DOI:  https://doi.org/10.1186/s40001-022-00703-1
Front Nutr. 2022 ;9 857879

Polydatin, A Glycoside of Resveratrol, Is Better Than Resveratrol in Alleviating Non-alcoholic Fatty Liver Disease in Mice Fed a High-Fructose Diet.

Guangshan Zhao, Lian Yang, Wenshen Zhong, Yuze Hu, Yu Tan, Zhe Ren, Qiuyan Ban, Chung S Yang, Yifei Wang, Zhiping Wang.

  Resveratrol (RES) is considered to be an activator of AMP-activated protein kinase (AMPK) with many reported health benefits. Polydatin (POD) is a natural precursor and glycosylated form of RES. The glycoside structure of POD alters the bioactivity. Overnutrition-stimulated reactive oxygen species (ROS) promote the AMPK suppression and metabolic dysregulation. The present work compared the effects of POD and RES in ameliorating energy homeostasis imbalance in mice fed a high-fructose diet and elucidated the underlying mechanisms of action. Our results showed that POD elevated the fecal levels of valeric acid and caproic acid via modification of gut microbiota, while RES did not significantly influence the levels of fecal short-chain fatty acids (SCFAs). Both POD and RES markedly decreased the oxidative stress and activated the AMPK signaling pathways in the liver. POD and RES exerted a similar effect in alleviating glucose dysmetabolism, but POD was more effective in ameliorating lipid dysmetabolism than RES. Furthermore, valeric acid and caproic acid alone can activate the AMPK and ameliorate hypercholesterolemia, and enhance the effects of POD on improving lipid metabolism in mice. Overall, for the first time, we demonstrated that POD administration elevated the fecal levels of valeric acid and caproic acid by modifying gut microbiota, thus promoting AMPK activation may be the underlying mechanism that POD is superior to RES in alleviating the lipid dysmetabolism. Our results suggest that POD may be an alternative for RES as an AMPK activator.

Keywords:  5′-aMP-activated protein kinase; gut microbiota; non-alcoholic fatty liver disease; polydatin; resveratrol; short-chain fatty acids

DOI:  https://doi.org/10.3389/fnut.2022.857879
Bioengineered. 2022 May;13(5): 13269-13279

Amentoflavone promotes ferroptosis by regulating reactive oxygen species (ROS) /5'AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) to inhibit the malignant progression of endometrial carcinoma cells.

Qi Sun, Peng Zhen, Dandan Li, Xiaochen Liu, Xinling Ding, Huihui Liu.

  It was reported that amentoflavone (AF) had anti-tumor ability. Therefore, this study aimed to investigate the role of AF in endometrial cancer as well as to discuss its underlying mechanism. The viability, proliferation, and apoptosis of endometrial carcinoma cells (KLE) with AF administration were detected by methyl tetrazolium (MTT) assay, clone formation, and terminal deoxynucleotidyl transferase (TdT) dUTP Nick-End Labeling (TUNEL) assays. Thiobarbituric acid reactive substance (TBARS) production and Fe2+ level in AF-treated KLE cells were detected by TBARS assay and Iron assay. The expressions of proliferation- apoptosis-, ferroptosis-, and 5'AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling-related proteins in AF-treated KLE cells were detected by western blot analysis. Reactive oxygen species (ROS) expression in AF-treated KLE cells was determined by ROS assay kit. N-acetyl cysteine (NAC), which is an inhibitor of ROS, was used to confirm whether AF exerted its effects on KLE cells through ROS/AMPK/mTOR signaling. As a result, AF inhibited the viability and proliferation of KLE cells but promoted apoptosis and ferroptosis. The expressions of ROS and AMPK were increased, while mTOR expression was decreased in AF-treated KLE cells. NAC reversed the effects of AF on biological behaviors of KLE cells by inactivating ROS/AMPK/mTOR signaling. In conclusion, AF promoted ferroptosis by activating ROS/AMPK/mTOR to inhibit the viability and proliferation and promoted the apoptosis and ferroptosis of KLE cells.

Keywords:  Amentoflavone; ROS/AMPK/mTOR; endometrial cancer cells; ferroptosis

DOI:  https://doi.org/10.1080/21655979.2022.2079256
Life Sci. 2022 May 28. pii: S0024-3205(22)00376-9. [Epub ahead of print] 120676

Genistein accelerates glucose catabolism via activation the GPER-mediated cAMP/PKA-AMPK signaling pathway in broiler chickens.

Qian Li, Ying Yang, Huihui Wang, Zhihao Jiang, Haitian Ma.

  Genistein, the most abundance of phytoestrogens in soybeans, has beneficial effects in regulating metabolism-related disease; however, there is few available literatures about whether genistein regulates glucose metabolism that in turn affects the lipid accumulation in animals or humans. The current study showed that genistein promoted glucose uptake by enhancing glucose transporter-2 (GLUT2) protein level; and it also increased the activity of phosphofructokinase-1 (PFK) and pyruvate dehydrogenase (PDH), and the mRNA level of succinate dehydrogenase (SDH) both in broiler chickens or hepatocytes. Moreover, genistein obviously increased the p-LKB1 and p-AMPKα protein levels both in vivo and in vitro. Furthermore, the enhancement of genistein on glucose uptake and catabolism were reversed in hepatocytes pre-treated with AMPK inhibitor Compound C, and the increasing of genistein on the p-LKB1 and p-AMPKα protein levels were also reversed in hepatocytes pre-treated with PKA inhibitor H89. Importantly, the results showed that genistein simultaneously increased the estrogen receptor β (ERβ) and G protein-coupled estrogen receptor (GPER) protein levels, but the elevation effect of genistein on cAMP content was completely reversed in hepatocytes pre-treated with GPER antagonist G15, rather than ERβ inhibitor PHTPP. Meanwhile, the increasing of p-LKB1 and p-AMPKα protein levels induced by genistein were also reversed in hepatocytes pre-treated with G15. Collectively, our data demonstrated that genistein improves glucose metabolism via activating the GPER-mediated cAMP/PKA-AMPK signaling pathway. These findings provide theoretical basis for genistein as a promising nutritional supplemental to alleviate metabolism disorders and related diseases in animals or even humans.

Keywords:  AMPK signal; Broiler chicken; GPER; Genistein; Glucose metabolism

DOI:  https://doi.org/10.1016/j.lfs.2022.120676
Cell Mol Gastroenterol Hepatol. 2022 May 25. pii: S2352-345X(22)00090-X. [Epub ahead of print]

Liver PP2A-Cα protects from parenteral nutrition-associated hepatic steatosis.

Gulisudumu Maitiabula, Feng Tian, Peng Wang, Li Zhang, Xuejin Gao, Songlin Wan, Haifeng Sun, Jianbo Yang, Yupeng Zhang, Tingting Gao, Bin Xue, Chaojun Li, Jieshou Li, Xinying Wang.

   BACKGROUND & AIMS: Parenteral nutrition (PN) is a lifesaving therapy for patients with intestinal failure. Hepatic steatosis is a potentially fatal complication of long-term PN, but the involved pathological mechanisms are incompletely unclarified. Herein, we identify the role of protein phosphatase 2A (PP2A) in the pathogenesis of parenteral nutrition-associated hepatic steatosis (PNAHS).
METHODS: Proteomic/phosphoproteomic analyses of liver samples from PNAHS patients were applied to identify the mechanism of PNAHS. Total parenteral nutrition (TPN) mice model, in vivo and in vitro experiments were used to assess the effect of PP2A-Cα on liver fatty acid metabolism.
RESULTS: Reduced expression of PP2A-Cα (catalytic subunit), enhanced activation of serine/threonine kinase Akt2 and decreased activation of adenosine monophosphate-activated protein kinase (AMPK) were associated with hepatic steatosis in PNAHS patients. Mice given PN for 14 days developed hepatic steatosis, down-regulation of PP2A-Cα, activation of Akt2 and inhibition of AMPK. Hepatocyte-specific deletion of PP2A-Cα in mice given PN exacerbated Akt2 activation, AMPK inhibition and hepatic steatosis through an effect on fatty acid degradation, whereas hepatocyte-specific PP2A-Cα overexpression significantly ameliorated hepatic steatosis accompanying with Akt2 suppression and AMPK activation. Additionally, pharmacological activation of Akt2 in mice overexpressing PP2A-Cα led to the aggravation of hepatic steatosis.
CONCLUSIONS: Our findings demonstrate that hepatic PP2A-Cα serves as a protective factor of PNAHS because of ameliorating hepatic steatosis and improving liver function. Our study provides a strong rationale that PP2A-Cα may be involved in the pathogenesis of PNAHS.

Keywords:  fatty acid degradation; parenteral nutrition-associated hepatic steatosis; protein phosphatase 2A

DOI:  https://doi.org/10.1016/j.jcmgh.2022.05.008
Biochim Biophys Acta Mol Basis Dis. 2022 May 26. pii: S0925-4439(22)00124-7. [Epub ahead of print]1868(9): 166454

Obesity induces adipose fibrosis and collagen cross-linking through suppressing AMPK and enhancing lysyl oxidase expression.

Xiangdong Liu, Liang Zhao, Yanting Chen, Yao Gao, Qiyu Tian, Jun Seok Son, Song Ah Chae, Jeanene Marie de Avila, Mei-Jun Zhu, Min Du.

  Collagen is the main component of connective tissue surrounding adipocytes. Collagen cross-linking affects adipose remodeling, which is crucial for maintaining function and metabolic homeostasis of adipose tissue. However, the effects of obesity on collagen cross-linking and adipose fibrosis remain to be examined. Therefore, the objective of this study was to investigate obesity-induced collagen cross-linking in adipose tissue and explore the underlying mechanisms. We found that obesity increased mature nonreducible collagen cross-linking in white adipose tissue (WAT) of mice, which was associated with inhibition of AMPK, up-regulation of transforming growth factor-β (TGF-β) signaling and the expression of lysyl oxidase (LOX), a key enzyme catalyzing the synthesis of mature cross-linking products. In SVCs and 3T3-L1 adipocytes, AMPK activation by metformin or AICAR inhibited TGF-β1-induced fibrogenesis and expression of LOX, which was further confirmed by ectopic expression of AMPK WT and K45R mutant. Consistently, in vivo, knocking out AMPK increased fibrosis and collagen cross-linking. Our study showed that AMPK downregulation due to obesity increases TGF-β signaling and LOX expression, which enhances adipose fibrosis and collagen cross-linking. Thus, AMPK is a therapeutic target for ameliorating the obesity-induced fibrosis, improving metabolic health of adipose tissue.

Keywords:  AMPK; Cross-linking; Fibrosis; Lysyl oxidase; Obesity

DOI:  https://doi.org/10.1016/j.bbadis.2022.166454
Cell Biosci. 2022 May 31. 12(1): 76

Bone morphogenetic protein signaling regulation of AMPK and PI3K in lung cancer cells and C. elegans.

Mehul Vora, Arindam Mondal, Dongxuan Jia, Pranya Gaddipati, Moumen Akel, John Gilleran, Jacques Roberge, Christopher Rongo, John Langenfeld.

   BACKGROUND: Bone morphogenetic protein (BMP) is a phylogenetically conserved signaling pathway required for development that is aberrantly expressed in several age-related diseases including cancer, Alzheimer's disease, obesity, and cardiovascular disease. Aberrant BMP signaling in mice leads to obesity, suggesting it may alter normal metabolism. The role of BMP signaling regulating cancer metabolism is not known.
METHODS: To examine BMP regulation of metabolism, C. elegans harboring BMP gain-of-function (gof) and loss-of-function (lof) mutations were examined for changes in activity of catabolic and anabolic metabolism utilizing Western blot analysis and fluorescent reporters. AMP activated kinase (AMPK) gof and lof mutants were used to examine AMPK regulation of BMP signaling. H1299 (LKB1 wild-type), A549 (LKB1 lof), and A549-LKB1 (LKB1 restored) lung cancer cell lines were used to study BMP regulation of catabolic and anabolic metabolism. Studies were done using recombinant BMP ligands to activate BMP signaling, and BMP receptor specific inhibitors and siRNA to inhibit signaling.
RESULTS: BMP signaling in both C. elegans and cancer cells is responsive to nutrient conditions. In both C. elegans and lung cancer cell lines BMP suppressed AMPK, the master regulator of catabolism, while activating PI3K, a regulator of anabolism. In lung cancer cells, inhibition of BMP signaling by siRNA or small molecules increased AMPK activity, and this increase was mediated by activation of LKB1. BMP2 ligand suppressed AMPK activation during starvation. BMP2 ligand decreased expression of TCA cycle intermediates and non-essential amino acids in H1299 cells. Furthermore, we show that BMP activation of PI3K is mediated through BMP type II receptor. We also observed feedback signaling, as AMPK suppressed BMP signaling, whereas PI3K increased BMP signaling.
CONCLUSION: These studies show that BMP signaling suppresses catabolic metabolism and stimulates anabolic metabolism. We identified feedback mechanisms where catabolic induced signaling mediated by AMPK negatively regulates BMP signaling, whereas anabolic signaling produces a positive feedback regulation of BMP signing through Akt. These mechanisms were conserved in both lung cancer cells and C. elegans. These studies suggest that aberrant BMP signaling causes dysregulation of metabolism that is a potential mechanism by which BMP promotes survival of cancer cells.

Keywords:  AMPK; Akt; BMP; BMPR2; LKB1; Lung cancer; Metabolism; PIK3; mTOR

DOI:  https://doi.org/10.1186/s13578-022-00817-3
Iran J Basic Med Sci. 2022 Feb;25(2): 198-207

Effect of alpha-mangostin on olanzapine-induced metabolic disorders in rats.

Alireza Ardakanian, Mahboobeh Ghasemzadeh Rahbardar, Farzaneh Omidkhoda, Bibi Marjan Razavi, Hossein Hosseinzadeh.

   Objectives: As olanzapine has side effects such as weight gain and metabolic disorders, and alpha-mangostin has been shown to control metabolic disorders, the effects of alpha-mangostin on metabolic disorders induced by olanzapine were investigated in this study.
Materials and Methods: Obesity was induced in female Wistar rats by daily administration of olanzapine (5 mg/kg/day, IP, 14 days). Rats were divided into 6 groups:1) vehicle (control); 2) olanzapine (5 mg/kg/day); 3,4,5) olanzapine+ alpha-mangostin (10, 20, 40 mg/kg/day, IP); 6) alpha-mangostin (40 mg/kg/day). Weight changes were measured every 3 days and food intake was assessed every day. Systolic blood pressure, plasma levels of blood sugar, triglycerides, total cholesterol, HDL, LDL, leptin, oxidative stress markers (MDA, GSH), AMPK, and P-AMPK protein levels in liver tissue were assessed on the last day of the study.
Results: Administration of olanzapine significantly increased weight gain, food intake, blood pressure, triglycerides, LDL, blood sugar, leptin, and MDA in rat liver tissue and also decreased GSH, AMPK, and P-AMPK in liver tissue compared with the control group. Different doses of alpha-mangostin significantly reduced weight gain, food intake, systolic blood pressure, triglycerides, LDL, blood sugar, leptin, and MDA. Also, they significantly increased GSH, AMPK, and P-AMPK in liver tissue compared with the olanzapine group.
Conclusion: Olanzapine increases leptin levels, food intake, and weight, induces oxidative stress, decreases the levels of AMPK and P-AMPK proteins in liver tissue, and causes metabolic disorders. But, alpha-mangostin reduces the negative effects of olanzapine by activation of AMPK.

Keywords:  Anti-oxidants; Leptin; Liver; Mangostin; Metabolic syndrome; Obesity; Olanzapine; Weight gain

DOI:  https://doi.org/10.22038/IJBMS.2022.58734.13047
Food Chem Toxicol. 2022 May 28. pii: S0278-6915(22)00388-X. [Epub ahead of print] 113190

Agomelatine, a structural analog of melatonin, improves kidney dysfunction through regulating the AMPK/mTOR signaling pathway to promote autophagy in obese rats.

Sasivimon Promsan, Laongdao Thongnak, Nattavadee Pengrattanachot, Nichakorn Phengpol, Prempree Sutthasupha, Anusorn Lungkaphin.

  This study aimed to investigate the renoprotective effect of agomelatine on kidney injury in an obese rat model and to understand the underlying mechanisms involving the AMPK-mTOR-autophagy signaling pathway. Male Wistar rats were fed either a normal (ND) or a high-fat diet (HF) for 16 weeks. The HF rats were divided into 4 groups: (1) HF control; (2) AGOM20 receiving agomelatine 20 mg. kg-1 day-1; (3) AGOM40 receiving agomelatine 40 mg. kg-1 day-1; and (4) NAC receiving N-acetylcysteine 100 mg. kg-1 day-1 by oral gavage for 4 weeks. HF rats demonstrated insulin resistance, impaired renal function and oxidative stress as evidenced by the elevation of MDA levels and expression of PKCα and NOX4. These alterations correlated with impaired autophagy, renal fibrosis and apoptosis. Agomelatine showed a greater efficacy than NAC treatment with regard to improving insulin resistance, dyslipidemia and renal dysfunction through alleviation of oxidative stress, fibrosis and apoptosis in kidney cells. Impaired autophagy was blunted after agomelatine or NAC administration, as demonstrated by the increased in Beclin-1, LC3B, Atg5, LAMP2, and AMPK, and decreased mTOR and CTSB expression. These data revealed that agomelatine protected against obesity-induced kidney injury via the regulation of ROS and AMPK-mTOR-autophagy signaling pathways.

Keywords:  Agomelatine; Autophagy; Insulin resistance; Obesity; Oxidative stress

DOI:  https://doi.org/10.1016/j.fct.2022.113190
Acta Pharmacol Sin. 2022 Jun 02.

Hepatocyte-derived MANF mitigates ethanol-induced liver steatosis in mice via enhancing ASS1 activity and activating AMPK pathway.

Han-Yang Xu, Yan-Hong Jiao, Shi-Yu Li, Xu Zhu, Sheng Wang, Yu-Yang Zhang, Yi-Jun Wei, Yu-Jun Shen, Wei Wang, Yu-Xian Shen, Jun-Tang Shao.

  Hepatic steatosis plays a detrimental role in the onset and progression of alcohol-associated liver disease (ALD). Mesencephalic astrocyte-derived neurotrophic factor (MANF) is an evolutionarily conserved protein related to the unfolded protein response. Recent studies have demonstrated that MANF plays an important role in liver diseases. In this study, we investigated the role of MANF in ethanol-induced steatosis and the underlying mechanisms. We showed that the hepatic MANF expression was markedly upregulated in mouse model of ALD by chronic-plus-single-binge ethanol feeding. Moreover, after chronic-plus-binge ethanol feeding, hepatocyte-specific MANF knockout (HKO) mice displayed more severe hepatic steatosis and liver injury than wild-type (WT) control mice. Immunoprecipitation-coupled MS proteomic analysis revealed that arginosuccinate synthase 1 (ASS1), a rate-limiting enzyme in the urea cycle, resided in the same immunoprecipitated complex with MANF. Hepatocyte-specific MANF knockout led to decreased ASS1 activity, whereas overexpression of MANF contributed to enhanced ASS1 activity in vitro. In addition, HKO mice displayed unique urea cycle metabolite patterns in the liver with elevated ammonia accumulation after ethanol feeding. ASS1 is known to activate AMPK by generating an intracellular pool of AMP from the urea cycle. We also found that MANF supplementation significantly ameliorated ethanol-induced steatosis in vivo and in vitro by activating the AMPK signaling pathway, which was partly ASS1 dependent. This study demonstrates a new mechanism in which MANF acts as a key molecule in maintaining hepatic lipid homeostasis by enhancing ASS1 activity and uncovers an interesting link between lipid metabolism and the hepatic urea cycle under excessive alcohol exposure.

Keywords:  alcohol-associated liver diseases; arginosuccinate synthase 1; hepatic urea cycle; liver steatosis; mesencephalic astrocyte-derived neurotrophic factor

DOI:  https://doi.org/10.1038/s41401-022-00920-8
Sci Rep. 2022 May 31. 12(1): 9062

Renal protection induced by physical exercise may be mediated by the irisin/AMPK axis in diabetic nephropathy.

Guilherme Pedron Formigari, Marcella Neves Dátilo, Beatriz Vareda, Ivan Luiz Padilha Bonfante, Claudia Regina Cavaglieri, Jacqueline M Lopes de Faria, José B Lopes de Faria.

In patients with diabetes, it has been suggested that physical exercise may reduce albuminuria and the progression of renal disease. However, the molecular mechanism by which physical exercise protects the kidney in diabetes remains poorly understood. The aim of the present study was to determine the contribution of muscle irisin secretion induced by aerobic physical exercise with the subsequent activation of AMPK for kidney protection under diabetic conditions. Aerobic physical exercise in rats protected the kidney in streptozotocin-induced diabetes. It reduced albuminuria, glomerular hypertrophy, and glomerular expression of collagen IV and fibronectin, as well as markers of kidney inflammation, when compared to sedentary diabetic rats. These effects were associated with elevation in muscle FNDC5/irisin and activity of AMPK in the diabetic kidney. However, the beneficial effects of exercise were lost when the diabetic rats were treated with CycloRGDyK, that in the bone it has been described as an irisin receptor blocker. In cultured human tubular (HK-2) cells, treatment with recombinant irisin counteracted the effect of high glucose in a dose-dependent manner. Irisin, per se, also activated AMPK in HK-2 cells. It is concluded that in diabetes, the renal protective effect of exercise may be mediated by the irisin/AMPK pathway.

DOI: https://doi.org/10.1038/s41598-022-13054-y
FASEB J. 2022 Jul;36(7): e22355

Mitochondrial phosphatidylethanolamine synthesis affects mitochondrial energy metabolism and quiescence entry through attenuation of Snf1/AMPK signaling in yeast.

Non Miyata, Takanori Ito, Miyu Nakashima, Satoru Fujii, Osamu Kuge.

  The Ups2-Mdm35 complex mediates intramitochondrial phosphatidylserine (PS) transport to facilitate mitochondrial phosphatidylethanolamine (PE) synthesis. In the present study, we found that ups2∆ yeast showed increased mitochondrial ATP production and enhanced quiescence (G0) entry in the post-diauxic shift phase. Transcriptomic and biochemical analyses revealed that the depletion of Ups2 leads to overactivation of the yeast AMPK homolog Snf1. Inactivation of Snf1 by depletion of an Snf1-activating kinase, Sak1 canceled the changes in mitochondrial ATP production and quiescence entry observed in ups2∆ cells. Furthermore, among the factors regulated by Snf1, upregulation of pyruvate carboxylase, Pyc1 and downregulation of acetyl-CoA carboxylase, Acc1, respectively, were sufficient to increase mitochondrial ATP production and quiescence entry. These results suggested that a normal PE synthesis mediated by Ups2-Mdm35 complex attenuates Snf1/AMPK activity, and that Snf1-mediated regulation of carbon metabolisms has great impacts on mitochondrial energy metabolism and quiescence entry. We also found that depletion of Ups2 together with the cell-cycle regulators Whi5 and Whi7, functional orthologs of the Rb1 tumor suppressor, caused a synthetic growth defect in yeast. Similarly, knockdown of PRELID3b, the human homolog of Ups2, decreased the viability of Rb1-deficient breast cancer cells, suggesting that PRELID3b is a potential target for cancer therapy.

Keywords:  Snf1/AMPK; Ups2-Mdm35 complex; carbon metabolism; mitochondrial energy metabolism; phosphatidylethanolamine; quiescence entry

DOI:  https://doi.org/10.1096/fj.202101600RR
Cell Rep. 2022 May 31. pii: S2211-1247(22)00659-3. [Epub ahead of print]39(9): 110884

Muscle satellite cells are impaired in type 2 diabetic mice by elevated extracellular adenosine.

Lifang Han, Gang Wang, Shaopu Zhou, Chenghao Situ, Zhiming He, Yuying Li, Yudan Qiu, Yu Huang, Aimin Xu, Michael Tim Yun Ong, Huating Wang, Jianfa Zhang, Zhenguo Wu.

  Muscle regeneration is known to be defective under diabetic conditions. However, the underlying mechanisms remain less clear. Adult quiescent muscle satellite cells (MuSCs) from leptin-receptor-deficient (i.e., db/db) diabetic mice are defective in early activation in vivo, but not in culture, suggesting the involvement of pathogenic niche factors. Elevated extracellular adenosine (eAdo) and AMP (eAMP) are detected under diabetic conditions. eAdo and eAMP potently inhibit cell cycle re-entry of quiescent MuSCs and injury-induced muscle regeneration. Mechanistically, eAdo and eAMP engage the equilibrative Ado transporters (ENTs)-Ado kinase (ADK)-AMPK signaling axis in MuSCs to inhibit the mTORC1-dependent cell growth checkpoint. eAdo and eAMP also inhibit early activation of quiescent fibroadipogenic progenitors and human MuSCs by the same mechanism. Treatment of db/db diabetic mice with an ADK inhibitor partially rescues the activation defects of MuSCs in vivo. Thus, both ADK and ENTs represent potential therapeutic targets for restoring the regenerative functions of tissue stem cells in patients with diabetes.

Keywords:  AMPK; CP: Metabolism; adenosine kinase (ADK); diabetes; equilibrative nucleoside transporter (ENT); extracellular AMP; extracellular adenosine; mTORC1; muscle satellite cells (MuSCs)

DOI:  https://doi.org/10.1016/j.celrep.2022.110884
Biochim Biophys Acta Mol Cell Res. 2022 May 27. pii: S0167-4889(22)00092-1. [Epub ahead of print] 119300

GLP-1 regulates exercise endurance and skeletal muscle remodeling via GLP-1R/AMPK pathway.

Luting Wu, Min Zhou, Tianyou Li, Niu Dong, Long Yi, Qianyong Zhang, Mantian Mi.

  Exercise-induced physical endurance enhancement and skeletal muscle remodeling can prevent and delay the development of multiple diseases, especially metabolic syndrome. Herein, the study explored the association between glucagon-like peptide-1 (GLP-1) secretion and exercise, and its effect on skeletal muscle remodeling to enhance endurance capacity. We found both acute exercise and short-term endurance training significantly increased the secretion of GLP-1 in mice. Recombinant adeno-associated virus (AAV) encoding Gcg (proglucagon) was used to induce the overexpression of GLP-1 in skeletal muscle of mice. Overexpression of GLP-1 in skeletal muscle enhanced endurance capacity. Meanwhile, glycogen synthesis, glucose uptake, type I fibers proportion, and mitochondrial biogenesis were augmented in GLP-1-AAV skeletal muscle. Furthermore, the in vitro experiment showed that exendin-4 (a GLP-1 receptor agonist) treatment remarkably promoted glucose uptake, type I fibers formation, and mitochondrial respiration. Mechanistically, the knockdown of AMPK could reverse the effects imposed by GLP-1R activation in vitro. Taken together, these results verify that GLP-1 regulates skeletal muscle remodeling to enhance exercise endurance possibly via GLP-1R signaling-mediated phosphorylation of AMPK.

Keywords:  Endurance capacity; GLP-1; Glycogen storage; Mitochondrial biogenesis; Muscle fiber type

DOI:  https://doi.org/10.1016/j.bbamcr.2022.119300
Food Chem. 2022 May 21. pii: S0308-8146(22)01246-8. [Epub ahead of print]391 133284

Selective transportation and energy homeostasis regulation of dietary advanced glycation end-products in human intestinal Caco-2 cells.

Yi Wu, Minhua Zong, Zhenhui Zhang, Yongtai Wu, Lin Li, Xia Zhang, Hong Wu, Bing Li.

  Advanced glycation end-products (AGEs) are a chemically heterogeneous set of modifications widely found in processed foods. Due to uncertain bioavailability, dietary AGEs regulate energy homeostasis through mechanisms that largely remain unclear. In this study, selective transmembrane transport of AGEs with different modification types from glycated β-casein digest were identified and compared. The results showed that only a few types of free and peptide-bound AGEs can easily cross the Caco-2 monolayers and thus exert their effects. A combination of biochemical assays, mitochondrial analyses, and comparative experiments identified that the effect of AGEs on cellular energy homeostasis comes mainly from their free fractions. Mechanistically, free AGEs arrest the mitochondrial differentiation and mtDNA repair by intervening in the function of thymidine phosphorylase, and interfering with mitochondrial energy production by inhibiting the activation of AMPK-SIRT6 signaling pathway. These results demonstrate mechanisms by which processed foods cause mitochondrial dysfunction and lead to dysfunctional energy homeostasis.

Keywords:  AMPK signaling pathway; Advanced glycation end-products; Energy homeostasis; Mitochondria; Transmembrane transport

DOI:  https://doi.org/10.1016/j.foodchem.2022.133284
Tissue Cell. 2022 May 21. pii: S0040-8166(22)00102-1. [Epub ahead of print]77 101830

Platelet-rich plasma contributes to chondroprotection by repairing mitochondrial function via AMPK/NF-κB signaling in osteoarthritic chondrocytes.

Ming Li, Hong Han, Liu Chen, Haohan Li.

  Osteoarthritis (OA), also known as degenerative osteoarthritis, has a complex etiology, and its pathogenesis remains unclear. Platelet-rich plasma (PRP) therapy has been widely used in medicine and other related professions since its clinical application was first reported in the 1980 s and the 1990 s. This study aimed to investigate the effects and potential mechanisms of PRP in OA. An in vitro model of osteoarthritis was constructed by lipopolysaccharide (LPS) stimulation, and the effect of PRP on LPS-induced chondrocytes was evaluated. The results indicated that although LPS inhibited chondrocyte proliferation and promoted inflammation and apoptosis, these effects were reversed by PRP. In addition, the LPS-suppressed expression of aggrecan, TGF-β, PDGF, and COL2A1 was restored by PRP, whereas the LPS-enhanced expression of MMP3 was suppressed by PRP. Furthermore, PRP inhibited LPS-induced mitochondrial damage by suppressing reactive oxygen species production, mitochondrial permeability transition pore opening, Drp1 expression, and upregulating Mfn1 expression. In addition, PRP inhibited the phosphorylation of AMPK and NF-κB. Collectively, this study indicates that PRP might be a potential therapeutic candidate for the treatment of OA by repairing mitochondrial function through the activation of AMPK/NF-κB signaling.

Keywords:  AMPK/NF-κB signaling pathway; Mitochondrial function; Osteoarthritis; Platelet-rich plasma

DOI:  https://doi.org/10.1016/j.tice.2022.101830
Redox Biol. 2022 May 18. pii: S2213-2317(22)00116-1. [Epub ahead of print]53 102344

TRIM22 inhibits osteosarcoma progression through destabilizing NRF2 and thus activation of ROS/AMPK/mTOR/autophagy signaling.

Wei Liu, Yuechao Zhao, Guangfu Wang, Shuang Feng, Xuhui Ge, Wu Ye, Zhuanghui Wang, Yufeng Zhu, Weihua Cai, Jianling Bai, Xuhui Zhou.

  Osteosarcoma (OS) is a malignant bone tumor that mainly occurs in adolescents. It is accompanied by a high rate of lung metastasis, and high mortality. Recent studies have suggested the important roles of tripartite motif-containing (TRIM) family proteins in regulating various substrates and signaling pathways in different tumors. However, the detailed functional role of TRIM family proteins in the progression of OS is still unknown and requires further investigations. In this study, we found that tripartite motif-containing 22 (TRIM22) was downregulated in OS tissues and was hence associated with better prognosis. In vitro and in vivo functional analysis demonstrated that TRIM22 inhibits proliferation and metastasis of OS cells. Nuclear factor erythroid 2-related factor 2 (NRF2), a redox regulator, was identified as a novel target for TRIM22. TRIM22 interacts with and accelerates the degradation of NRF2 by inducing its ubiquitination dependent on its E3 ligase activity but independent of Kelch-like ECH-associated protein 1 (KEAP1). Further, a series of gain- and loss-of-function experiments showed that knockdown or overexpression of NRF2 reversed the functions of knockdown or overexpression of TRIM22 in OS. Mechanistically, TRIM22 inhibited OS progression through NRF2-mediated intracellular reactive oxygen species (ROS) imbalance. ROS production was significantly promoted and mitochondrial potential was remarkably inhibited when overexpressing TRIM22, thus activating AMPK/mTOR signaling. Moreover, TRIM22 was also found to inhibit Warburg effect in OS cells. Autophagy activation was found in OS cells which were overexpressed TRIM22, thus leading to autophagic cell death. Treatment with N-Acetylcysteine (NAC), a ROS scavenger or the autophagy inhibitor 3-Methyladenine (3-MA) abolished the decreased malignant phenotypes in TRIM22 overexpressing OS cells. In conclusion, our study indicated that TRIM22 inhibits OS progression by promoting proteasomal degradation of NRF2 independent of KEAP1, thereby activating ROS/AMPK/mTOR/Autophagy signaling that leads to autophagic cell death in OS. Therefore, our findings indicated that targeting TRIM22/NRF2 could be a promising therapeutic target for treating OS.

Keywords:  Autophagic cell death; Osteosarcoma; ROS; TRIM22/NRF2; Warburg effect

DOI:  https://doi.org/10.1016/j.redox.2022.102344