bims-amsmem 2022-11-20 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2022‒11‒20
nineteen papers selected by
Dipsikha Biswas, Københavns Universitet

AMP-activated protein kinase - a journey from 1 to 100 downstream targets.
High-fat diet and palmitate inhibits FNDC5 expression via AMPK-Zfp57 pathway in mouse muscle cells.
Metformin: Activation of 5' AMP-activated protein kinase and its emerging potential beyond anti-hyperglycemic action.
Prior AICAR induces elevated glucose uptake concomitant with greater γ3-AMPK activation and reduced membrane cholesterol in skeletal muscle from 26-month-old rats.
Metformin-induced AMPK activation promotes cisplatin resistance through PINK1/Parkin dependent mitophagy in gastric cancer.
Exercise training attenuates angiotensin II-induced cardiac fibrosis by reducing POU2F1 expression.
Trans-gnetin H isolated from the seeds of Paeonia species induces autophagy via inhibiting mTORC1 signalling through AMPK activation.
Energy sensor AMPK gamma regulates translation via phosphatase PPP6C independent of AMPK alpha.
Exercise-induced specialized proresolving mediators stimulate AMPK phosphorylation to promote mitochondrial respiration in macrophages.
Lactobacillus improves meat quality in Sunit sheep by affecting mitochondrial biogenesis through the AMPK pathway.
The propofol-induced mitochondrial damage in fetal rat hippocampal neurons via the AMPK/P53 signaling pathway.
Mitochonic acid 5 ameliorates the motor deficits in the MPTP-induced mouse Parkinson's disease model by AMPK-mediated autophagy.
AMPK/Sirt1-mediated inflammation is positively correlated with myocardial fibrosis during ageing.
AMPK directly phosphorylates TBK1 to integrate glucose sensing into innate immunity.
Metformin can mitigate skeletal dysplasia caused by Pck2 deficiency.
Ribosome stalling is a signal for metabolic regulation by the ribotoxic stress response.
STING promotes proliferation and induces drug resistance in colorectal cancer by regulating the AMPK-mTOR pathway.
AMPK activator AICAR in combination with anti-mouse IL10 mAb restores the functionality of intra-tumoral Tfh cells in the 4T1 mouse model.
Luteoloside pretreatment attenuates anoxia-induced damage in cardiomyocytes by regulating autophagy mediated by 14-3-3η and the AMPKα-mTOR/ULK1 pathway.

Biochem J. 2022 Nov 30. 479(22): 2327-2343

AMP-activated protein kinase - a journey from 1 to 100 downstream targets.

D Grahame Hardie.

  A casual decision made one evening in 1976, in a bar near the Biochemistry Department at the University of Dundee, led me to start my personal research journey by following up a paper that suggested that acetyl-CoA carboxylase (ACC) (believed to be a key regulatory enzyme of fatty acid synthesis) was inactivated by phosphorylation by what appeared to be a novel, cyclic AMP-independent protein kinase. This led me to define and name the AMP-activated protein kinase (AMPK) signalling pathway, on which I am still working 46 years later. ACC was the first known downstream target for AMPK, but at least 100 others have now been identified. This article contains some personal reminiscences of that research journey, focussing on: (i) the early days when we were defining the kinase and developing the key tools required to study it; (ii) the late 1990s and early 2000s, an exciting time when we and others were identifying the upstream kinases; (iii) recent times when we have been studying the complex role of AMPK in cancer. The article is published in conjunction with the Sir Philip Randle Lecture of the Biochemical Society, which I gave in September 2022 at the European Workshop on AMPK and AMPK-related kinases in Clydebank, Scotland. During the early years of my research career, Sir Philip acted as a role model, due to his pioneering work on insulin signalling and the regulation of pyruvate dehydrogenase.

Keywords:  history; intracellular signaling; phosphorylation/dephosphorylation; protein-serine–threonine kinases

DOI:  https://doi.org/10.1042/BCJ20220255
Chem Biol Interact. 2022 Nov 11. pii: S0009-2797(22)00470-7. [Epub ahead of print] 110265

High-fat diet and palmitate inhibits FNDC5 expression via AMPK-Zfp57 pathway in mouse muscle cells.

Qian Guo, Boya Zhang, Haining Du, Ruijiao Zhu, Xiaotong Sun, Xingpei Fan, Xiangjuan Wei, DaQian Yang, Yuri Oh, Lei Fan, Changlin Wang, Ning Gu.

  Irisin, a muscle-secreted cytokine involved in maintaining glucose homeostasis and improving insulin resistance, is generated from the precursor fibronectin type Ⅲ domain-containing protein 5 (FNDC5) by specific proteases. Zinc-finger protein Zfp57, a transcription factor that maintains the methylation during early embryonic development, is also reported to be associated with diabetes mellitus. However, the association between Zfp57 and FNDC5 is still unclear. In our study, we explored the detailed regulatory effect of Zfp57 on FNDC5 expression. In this study, we found that high-fat diet or saturated fatty acid palmitate increased the Zfp57 expression and decreased FNDC5 expression in muscle tissue or C2C12 myotubes. RNA sequencing analysis disclosed effects of the high-fat diet on genes associated with insulin resistance and the AMP-activated protein kinase (AMPK) signaling pathway in muscle tissue of mice. Chromatin immunoprecipitation experiments revealed that Zfp57 binds the FNDC5 gene promoter at positions -308 to -188. Moreover, Zfp57 overexpression inhibited FNDC5 expression, and Zfp57 knockdown alleviated the inhibitory effect of palmitate on FNDC5 expression in C2C12 myotubes. In addition, in vivo and in vitro studies demonstrated that activation of the AMPK pathway by 5-Aminoimidazole-4-carboxamide riboside (AICAR) or metformin mitigated the inhibitory effect of Zfp57 on FNDC5 expression and improved insulin resistance. These findings collectively suggest that high-fat diet and palmitate inhibit the AMPK pathway to increase Zfp57 expression, which in turn induces FNDC5 inhibition, to further aggravate insulin resistance.

Keywords:  AMPK; FNDC5; High-fat diet; Palmitate; Zfp57

DOI:  https://doi.org/10.1016/j.cbi.2022.110265
Front Genet. 2022 ;13 1022739

Metformin: Activation of 5' AMP-activated protein kinase and its emerging potential beyond anti-hyperglycemic action.

Sanjay Goel, Ravinder Singh, Varinder Singh, Harmanjit Singh, Pratima Kumari, Hitesh Chopra, Rohit Sharma, Eugenie Nepovimova, Martin Valis, Kamil Kuca, Talha Bin Emran.

  Metformin is a plant-based drug belonging to the class of biguanides and is known to treat type-2 diabetes mellitus (T2DM). The drug, combined with controlling blood glucose levels, improves the body's response to insulin. In addition, trials have identified the cardioprotective potential of metformin in the diabetic population receiving the drug. Activation of 5' AMP-activated protein kinase (AMPK) is the major pathway for these potential beneficial effects of metformin. Historically, much emphasis has been placed on the potential indications of metformin beyond its anti-diabetic use. This review aims to appraise other potential uses of metformin primarily mediated by the activation of AMPK. We also discuss various mechanisms, other than AMPK activation, by which metformin could produce beneficial effects for different conditions. Databases including PubMed/MEDLINE and Embase were searched for literature relevant to the review's objective. Reports from both research and review articles were considered. We found that metformin has diverse effects on the human body systems. It has been shown to exert anti-inflammatory, antioxidant, cardioprotective, metabolic, neuroprotective, anti-cancer, and antimicrobial effects and has now even been identified as effective against SARS-CoV-2. Above all, the AMPK pathway has been recognized as responsible for metformin's efficiency and effectiveness. Owing to its extensive potential, it has the capability to become a part of treatment regimens for diseases apart from T2DM.

Keywords:  anticancer; cardioprotective; hyperglycemia; metformin; oxidative stress

DOI:  https://doi.org/10.3389/fgene.2022.1022739
Facets (Ott). 2022 Jan;7 774-791

Prior AICAR induces elevated glucose uptake concomitant with greater γ3-AMPK activation and reduced membrane cholesterol in skeletal muscle from 26-month-old rats.

Haiyan Wang, Amy Zheng, Edward B Arias, Gregory D Cartee.

  Attenuated skeletal muscle glucose uptake (GU) has been observed with advancing age. It is important to elucidate the mechanisms linked to interventions that oppose this detrimental outcome. Earlier research using young rodents and (or) cultured myocytes reported that treatment with 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR; an AMP-activated protein kinase (AMPK) activator) can increase γ3-AMPK activity and reduce membrane cholesterol content, each of which has been proposed to elevate GU. However, the effect of AICAR treatment on γ3-AMPK activity and membrane cholesterol in skeletal muscle of aged animals has not been reported. Our purpose was to evaluate the effects of AICAR treatment on these potential mechanisms for enhanced glucose uptake in the skeletal muscle of aged animals. Epitrochlearis muscles from 26-27-month-old male rats were isolated and incubated ± AICAR, followed by 3 h incubation without AICAR, and then incubation with 3-O-methyl-[3 H] glucose (to assess GU ± insulin). Muscles were also analyzed for γ3-AMPK activity and membrane cholesterol content. Prior AICAR treatment led to increased γ3-AMPK activity, reduced membrane cholesterol content, and enhanced glucose uptake in skeletal muscle from aged rats. These observations revealed that two potential mechanisms for greater GU previously observed in younger animals and (or) cell models are also potentially relevant for enhanced GU by muscles from older animals.

Keywords:  AMP-activated protein kinase; aging; cholesterol; glucose transport; insulin sensitivity; skeletal muscle

DOI:  https://doi.org/10.1139/facets-2021-0166
Front Oncol. 2022 ;12 956190

Metformin-induced AMPK activation promotes cisplatin resistance through PINK1/Parkin dependent mitophagy in gastric cancer.

Yi-Yi Xiao, Jin-Xing Xiao, Xiao-Yu Wang, Tao Wang, Xin-Hui Qu, Li-Ping Jiang, Fang-Fang Tou, Zhi-Ping Chen, Xiao-Jian Han.

  Gastric cancer (GC) is one of the most common tumors worldwide, and cisplatin is a standard chemotherapeutic reagent for GC treatment. However, chemoresistance is an inherent challenge which limits its application and effectiveness in clinic. This study aims to investigate the mechanism of metformin-induced cisplatin resistance in GC. Intriguingly, the upregulation of mitophagy markers, mitochondrial fission, autophagy and mitophagosome were observed in SGC-7901/DDP cells compared to those in the SGC-7901 cells. Treatment with metformin significantly increased mitochondrial fission and mitophagy in both AGS and SGC-7901 cells, resulting in decreased ATP production, which unexpectedly protected GC cells against the cytotoxicity of cisplatin. In contrast, application of Chloroquine and 3-methyladenine, two inhibitors of autophagy, significantly alleviated the protective effect of metformin on SGC-7901 and AGS cells against cytotoxicity of cisplatin. Moreover, metformin also stimulated the phosphorylation of AMPK (Thr172) and increased the expression of mitophagy markers including Parkin and PINK1 in the AMPK signaling-dependent manner. Consistently, the cell viability and cell apoptosis assay showed that metformin-induced cisplatin resistance was prevented by knockdown of AMPKα1. Taken together, all data in this study indicate that metformin induced AMPK activation and PINK1/Parkin dependent mitophagy, which may contribute to the progression of cisplatin resistance in GC.

Keywords:  AMPK; cisplatin resistance; gastric cancer; metformin; mitophagy

DOI:  https://doi.org/10.3389/fonc.2022.956190
J Sport Health Sci. 2022 Oct 29. pii: S2095-2546(22)00104-1. [Epub ahead of print]

Exercise training attenuates angiotensin II-induced cardiac fibrosis by reducing POU2F1 expression.

Na Feng, Haiyi Yu, Yueshen Wang, Youyi Zhang, Han Xiao, Wei Gao.

  PURPOSE: Exercise training protects against heart failure. However, the mechanism underlying the protective effect of exercise training on angiotensin II (Ang II)-induced cardiac fibrosis remains unclear.METHODS: An exercise model involving C57BL/6N mice and 6 weeks of treadmill training was used. Ang II (1.44 mg/kg/day) was administered to induce cardiac fibrosis. RNA sequencing and bioinformatic analysis were used to identify the key factors mediating the effects of exercise training on cardiac fibrosis. Primary adult mouse cardiac fibroblasts (CFs) were used in vitro. Adeno-associated virus serotype 9 was used to overexpress POU domain, class 2, transcription factor 1 (POU2F1) in vivo.
RESULTS: Exercise training attenuated Ang II-induced cardiac fibrosis and reversed 39 gene expression changes. The transcription factor regulating the largest number of these genes was POU2F1. Compared to controls, POU2F1 was shown to be significantly upregulated by Ang II, which is itself reduced by exercise training. In vivo, POU2F1 overexpression nullified the benefits of exercise training on cardiac fibrosis. In CFs, POU2F1 promoted cardiac fibrosis. CCAAT enhancer-binding protein β (C/EBPβ) was predicted to be the transcription factor of POU2F1 and verified using a dual-luciferase reporter assay. In vivo, exercise training activated AMP-activated protein kinase (AMPK) and alleviated the increase in C/EBPβ induced by Ang II. In CFs, AMPK agonist inhibited the increase in C/EBPβ and POU2F1 induced by Ang II, whereas AMPK inhibitor reversed this effect.
CONCLUSION: Exercise training attenuates Ang II-induced cardiac fibrosis by reducing POU2F1. Exercise training inhibits POU2F1 by activating AMPK, which is followed by the downregulation of C/EBPβ, the transcription factor of POU2F1.

Keywords:  AMPK; C/EBPβ; Cardiac fibrosis; Exercise; POU2F1

DOI:  https://doi.org/10.1016/j.jshs.2022.10.004
Cell Prolif. 2022 Nov 15. e13360

Trans-gnetin H isolated from the seeds of Paeonia species induces autophagy via inhibiting mTORC1 signalling through AMPK activation.

Chao Xia, Guoyan Wang, Lei Chen, Huijun Geng, Junhu Yao, Zhangzhen Bai, Lu Deng.

Paeonia is a well-known species of ornamental plants, traditional Chinese medicines, and emerging oilseed crops. Apart from nutritional unsaturated fatty acids, the seeds of peonies are rich in stilbenes characterized by their wide-ranging health-promoting properties. Although the typical stilbene resveratrol has been widely reported for its multiple bioactivities, it remains uncertain whether the trimer of resveratrol trans-gnetin H has properties that regulate cancer cell viability, let alone the underlying mechanism. Autophagy regulated by trans-gnetin H was detected by western blotting, immunofluorescence, and quantitative real-time PCR. The effects of trans-gnetin H on apoptosis and proliferation were examined by flow cytometry, colony formation and Cell Counting Kit-8 assays. Trans-gnetin H significantly inhibits cancer cell viability through autophagy by suppressing the phosphorylation of TFEB and promoting its nuclear transport. Mechanistically, trans-gnetin H inhibits the activation and lysosome translocation of mTORC1 by inhibiting the activation of AMPK, indicating that AMPK is a checkpoint for mTORC1 inactivation induced by trans-gnetin H. Moreover, the binding of TSC2 to Rheb was markedly increased in response to trans-gnetin H stimulation. Similarly, trans-gnetin H inhibited the interaction between Raptor and RagC in an AMPK-dependent manner. More importantly, trans-gnetin H-mediated autophagy highly depends on the AMPK-mTORC1 axis. We propose a regulatory mechanism by which trans-gnetin H inhibits the activation of the mTORC1 pathway to control cell autophagy.

DOI: https://doi.org/10.1111/cpr.13360
Mol Cell. 2022 Nov 08. pii: S1097-2765(22)01058-9. [Epub ahead of print]

Energy sensor AMPK gamma regulates translation via phosphatase PPP6C independent of AMPK alpha.

Qi Zhou, Bingbing Hao, Xiaolei Cao, Lin Gao, Zhenyue Yu, Yang Zhao, Mingrui Zhu, Guoxuan Zhong, Fangtao Chi, Xiaoming Dai, Jizhong Mao, Yibing Zhu, Ping Rong, Liang Chen, Xueli Bai, Cunqi Ye, Shuai Chen, Tingbo Liang, Li Li, Xin-Hua Feng, Minjia Tan, Bin Zhao.

  Maintenance of energy level to drive movements and material exchange with the environment is a basic principle of life. AMP-activated protein kinase (AMPK) senses energy level and is a major regulator of cellular energy responses. The gamma subunit of AMPK senses elevated ratio of AMP to ATP and allosterically activates the alpha catalytic subunit to phosphorylate downstream effectors. Here, we report that knockout of AMPKγ, but not AMPKα, suppressed phosphorylation of eukaryotic translation elongation factor 2 (eEF2) induced by energy starvation. We identified PPP6C as an AMPKγ-regulated phosphatase of eEF2. AMP-bound AMPKγ sequesters PPP6C, thereby blocking dephosphorylation of eEF2 and thus inhibiting translation elongation to preserve energy and to promote cell survival. Further phosphoproteomic analysis identified additional targets of PPP6C regulated by energy stress in an AMPKγ-dependent manner. Thus, AMPKγ senses cellular energy availability to regulate not only AMPKα kinase, but also PPP6C phosphatase and possibly other effectors.

Keywords:  AMPK; PPP6C; eEF2; energy level; phosphorylation

DOI:  https://doi.org/10.1016/j.molcel.2022.10.030
Mol Metab. 2022 Nov 15. pii: S2212-8778(22)00206-X. [Epub ahead of print] 101637

Exercise-induced specialized proresolving mediators stimulate AMPK phosphorylation to promote mitochondrial respiration in macrophages.

Ernesto Pena Calderin, Jing-Juan Zheng, Nolan L Boyd, Lindsey McNally, Pawel Lorkiewicz, Bradford G Hill, Jason Hellmann.

  OBJECTIVE: Physical activity has been shown to reduce the risk of CVD mortality in large-cohort longitudinal studies; however, the mechanisms underpinning the beneficial effects of exercise remain incompletely understood. Emerging data suggest that the risk reducing effect of exercise extends beyond changes in traditional CVD risk factors alone and involves alterations in immunity and reductions in inflammatory mediator production. Our study aimed to determine whether exercise-enhanced production of proresolving lipid mediators contribute to alterations in macrophage intermediary metabolism, which may contribute to the anti-inflammatory effects of exercise.METHODS: Changes in lipid mediators and macrophage metabolism were assessed in C57Bl/6 mice following 4 weeks of voluntary exercise training. To investigate whether exercise-stimulated upregulation of specialized proresolving lipid mediators (SPMs) was sufficient to enhance mitochondrial respiration, both macrophages from control mice and human donors were incubated in vitro with SPMs and mitochondrial respiratory parameters were measured using extracellular flux analysis. Compound-C, an ATP-competitive inhibitor of AMPK kinase activity, was used to investigate the role of AMPK activity in SPM-induced mitochondrial metabolism. To assess the in vivo contribution of 5-lipoxygenase in AMPK activation and exercise-induced mitochondrial metabolism in macrophages, Alox5-/- mice were also subjected to exercise training.
RESULTS: Four weeks of exercise training enhanced proresolving lipid mediator production, while also stimulating the catabolism of inflammatory lipid mediators (e.g., leukotrienes and prostaglandins). This shift in lipid mediator balance following exercise was associated with increased macrophage mitochondrial metabolism. We also find that treating human and murine macrophages in vitro with proresolving lipid mediators enhances mitochondrial respiratory parameters. The proresolving lipid mediators RvD1, RvE1, and MaR1, but not RvD2, stimulated mitochondrial respiration through an AMPK-dependent signaling mechanism. Additionally, in a subset of macrophages, exercise-induced mitochondrial activity in vivo was dependent upon 5-lipoxygenase activity.
CONCLUSION: Collectively, these results suggest that exercise stimulates proresolving lipid mediator biosynthesis and mitochondrial metabolism in macrophages via AMPK, which might contribute to the anti-inflammatory and CVD risk reducing effect of exercise.

Keywords:  exercise; inflammation; lipid mediators; macrophage; mitochondria

DOI:  https://doi.org/10.1016/j.molmet.2022.101637
Front Nutr. 2022 ;9 1030485

Lactobacillus improves meat quality in Sunit sheep by affecting mitochondrial biogenesis through the AMPK pathway.

Chenlei Wang, Xinlei Yan, Yanping Bai, Lina Sun, Lihua Zhao, Ye Jin, Lin Su.

  Sunit sheep are famous for their high meat quality, but the meat quality of them has declined due to the change in feeding methods. Lactobacillus has a variety of probiotic effects and is widely used in animal diets to optimize meat quality. This study aimed to investigate the effect of dietary supplementation with different levels of Lactobacillus on meat quality. A total of 24 3-month-old Sunit sheep with an average body weight of 19.03 ± 3.67 kg were randomly divided into control (C), 1% (L1), 2% (L2), and 3% Lactobacillus groups (L3), with 6 sheep in each group. Myofiber characteristics, meat quality, and metabolic enzyme activity were detected. Moreover, the regulatory mechanism of Lactobacillus on meat quality was explored by using Western blotting and real-time Quantitative polymerase chain reaction (RT-qPCR). The results showed that dietary addition of Lactobacillus decreased LDH activity in the Biceps femoris of Sunit sheep (P < 0.05). Compared to the other groups, the 1% Lactobacillus group showed the conversion of myofibers from the glycolytic to the oxidative type, and the increasing b* values (P < 0.05), decreasing shear force and cooking loss of meat (P < 0.05) and the relative gene and protein expression levels of AMPK, PGC-1α, NRF1, TFAM, and COX IV (P < 0.05) in the Biceps femoris were also increased in the 1% Lactobacillus group. Therefore, the addition of Lactobacillus to the diet of Sunit sheep could regulate the AMPK signaling pathway to promote myofiber type conversion, which improves meat quality. This study provided a theoretical and data basis for improving the meat quality of sheep and supplied a novel way of applying Lactobacillus.

Keywords:  AMPK pathway; Lactobacillus; meat quality; mitochondrial biogenesis; myofiber

DOI:  https://doi.org/10.3389/fnut.2022.1030485
Ann Transl Med. 2022 Oct;10(20): 1106

The propofol-induced mitochondrial damage in fetal rat hippocampal neurons via the AMPK/P53 signaling pathway.

Fei Xiao, Yi Qin, Jing Chen, Chunlai Li, Yinying Qin, Yi Wei, Yubo Xie.

  Background: Propofol is a commonly used general anesthetic that may cause neuronal damage, especially in infants and young children. Mitochondria play an essential role in cellular metabolism and signal transduction. Propofol may cause neurotoxicity by inhibiting mitochondrial function, but the mechanism by this which occurs remains unclear.Methods: First, the primary rat hippocampal neurons were cultured for 7 days in vitro. The neurons were incubated with propofol at different times or different concentrations, and then the adenosine triphosphate (ATP), reactive oxygen species (ROS), mitochondrial membrane potential, and apoptosis-related proteins were analyzed. Based on the results of the 1st phase, the neurons were then incubated with propofol (100 µM) or corresponding reagents, including 5-aminoimidazole-4-carboxamide ribonucleotide, tenovin-1, and pifithrin-α. Subsequently, the ATP, ROS, mitochondrial membrane potential, phospho-adenosine 5'-monophosphate-activated protein kinase (p-AMPK), protein 53 (p53), and related apoptosis proteins were analyzed.
Results: Higher propofol concentrations or longer incubation times were associated with more pronounced decreases in ATP, B-cell lymphoma 2 (Bcl-2), and mitochondrial membrane potential, and more pronounced increases in ROS, BCL2-associated X (Bax), Cytochrome C (CytC), and cleaved caspase-9. Additionally, after incubation with propofol (100 µM), neuronal Bcl-2, p-AMPK, ATP, and mitochondrial membrane potential were downregulated, and ROS, p53, CytC, Bax, cleaved caspase-3, and cleaved caspase-9 were upregulated. AMPK activators or p53 inhibitors reversed the above-mentioned changes.
Conclusions: Propofol (100 µM)-induced mitochondrial damage in fetal rat hippocampal neurons may be mediated by the AMPK/p53 signaling pathway. Propofol (100 µM) was shown to inhibit the activity of AMPK in neurons, upregulate the expression of p53, and then activate the mitochondrial-dependent apoptosis pathway, which may lead to neuronal apoptosis.

Keywords:  Propofol; adenosine 5'-monophosphate (AMP)-activated protein kinase; hippocampal; mitochondria; p53

DOI:  https://doi.org/10.21037/atm-22-4374
Folia Neuropathol. 2022 ;pii: 47655. [Epub ahead of print]60(3): 329-337

Mitochonic acid 5 ameliorates the motor deficits in the MPTP-induced mouse Parkinson's disease model by AMPK-mediated autophagy.

Juan Wan, Yijiang Gao, Jian Tan, Shanqing Yi, Kailiang Huang, Yao Liu, Dong Chang, Jiali Xie, Shuangxi Chen, Heng Wu.

  Parkinson's disease (PD) is a well-known neurodegenerative disorder characterized by the degeneration of dopaminergic neurons, and oxidative stress and neuroinflammation are also associated with the pathogenesis of PD. Mitochonic acid 5 (MA-5), an analogue of indole-3-acetic acid, exerts key protective roles in inhibiting apoptosis, oxidative stress and neuroinflammation in multiple diseases. However, whether MA-5 can be beneficial for PD remains unclear. Hence, the aim of this study was to investigate the neuroprotective role of MA-5 in PD. In the current study, MPTP-challenged mice were treated as the in vivo model, and the effect of MA-5 on the motor function, neuronal survival, oxidative stress, neuroinflammation and the underlying mechanisms involved with AMPK and autophagy were determined. We revealed that MA-5 obviously up-regulated the phosphorylation of AMPK and promoted the autophagy (indicated by the increased LC3II/LC3I, parkin, pink and decreased p62) in substantia nigra (SN), ameliorated the motor deficits, up-regulated the expression of TH, suppressed the inflammation (indicated by the decreased protein levels of interleukin (IL)-1b, IL-6, tumour necrosis factor a) in SN in MPTP-induced mice. However, these patterns were reversed after the treatment of Compound C, an inhibitor of AMPK; also, after the application of CSA, an inhibitor of autophagy, MA-5 cannot play against the neurotoxicity of MPTP in mice. These combined results suggest that MA-5 can protect against MPTP-induced neurotoxicity to ameliorate the impaired motor function, which may be modulated via activation of AMPK-induced autophagy.

Keywords:   AMPK; autophagy.; mitochonic acid 5 (MA-5); Parkinson's disease (PD)

DOI:  https://doi.org/10.5114/fn.2022.118796
Acta Cardiol. 2022 Nov 15. 1-10

AMPK/Sirt1-mediated inflammation is positively correlated with myocardial fibrosis during ageing.

Yanan Song, Yaqing Zhang, Xulan Zhang, Shanshan Hu, Jin'er Wang, Gaigai Deng, Zhiyong Zhou.

  OBJECTIVES: Cardiovascular disease is the leading cause of death in the world, and it increases dramatically with ageing. The objective of this study was to elucidate age-dependent molecular changes of inflammation and its correlation with the progression of myocardial fibrosis.METHODS: Methods: Male SD rats aged 3, 6, 9 and 24 months were used in this study. H&E staining was used to assessed histo-morphological changes in different ages. Masson's trichrome staining was used to evaluate myocardial fibrosis. Immunofluorescence as well as western blot was carried out to detect the expression of vimentin. Real-time PCR was used to detect the level of pro-inflammatory chemokines MCP-1, IL1β, TNFα and IL-6. Western blotting was also carried out to detect p-AMPK, Sirt1, AC-NF-κB expression.
RESULTS: Myocardial pathological changes and fibrosis are positively correlated with age. Ageing rats showed an enhanced expression of inflammatory factors and the activation of cardiac fibroblasts increases. Meanwhile, the expression of p-AMPK, Sirt1 and downstream AC-NF-κB increased significantly during ageing. Furthermore, the 15-24 months of age in rats is the fastest changing stage of increased inflammation and decreased Sirt1 activity.
CONCLUSIONS: Ageing is an independent risk factor for the occurrence and development of myocardial fibrosis. During ageing, myocardial fibroblasts are activated, accompanied by an increase in extracellular matrix deposition. The inflammation mediated by AMPK/Sirt1/NF-κB signalling pathway is closely positively correlated with the activation of myocardial fibroblasts and the progression of myocardial fibrosis.

Keywords:  AMPK/Sirt1 signalling pathway; Ageing; NF-κB; cardiac fibroblast; inflammation; myocardial fibrosis

DOI:  https://doi.org/10.1080/00015385.2022.2119667
Mol Cell. 2022 Nov 08. pii: S1097-2765(22)01054-1. [Epub ahead of print]

AMPK directly phosphorylates TBK1 to integrate glucose sensing into innate immunity.

Qian Zhang, Shengduo Liu, Chen-Song Zhang, Qirou Wu, Xinyuan Yu, Ruyuan Zhou, Fansen Meng, Ailian Wang, Fei Zhang, Shasha Chen, Xiaojian Wang, Lei Li, Jun Huang, Yao-Wei Huang, Jian Zou, Jun Qin, Tingbo Liang, Xin-Hua Feng, Sheng-Cai Lin, Pinglong Xu.

  Nutrient sensing and damage sensing are two fundamental processes in living organisms. While hyperglycemia is frequently linked to diabetes-related vulnerability to microbial infection, how body glucose levels affect innate immune responses to microbial invasion is not fully understood. Here, we surprisingly found that viral infection led to a rapid and dramatic decrease in blood glucose levels in rodents, leading to robust AMPK activation. AMPK, once activated, directly phosphorylates TBK1 at S511, which triggers IRF3 recruitment and the assembly of MAVS or STING signalosomes. Consistently, ablation or inhibition of AMPK, knockin of TBK1-S511A, or increased glucose levels compromised nucleic acid sensing, while boosting AMPK-TBK1 cascade by AICAR or TBK1-S511E knockin improves antiviral immunity substantially in various animal models. Thus, we identify TBK1 as an AMPK substrate, reveal the molecular mechanism coupling a dual sensing of glucose and nuclei acids, and report its physiological necessity in antiviral defense.

Keywords:  AMPK; TBK1; antiviral immunity; cGAS-STING; coronavirus; glucose metabolism; hyperglycemia; innate immunity; viral infection; virus-host interactions

DOI:  https://doi.org/10.1016/j.molcel.2022.10.026
Int J Oral Sci. 2022 11 15. 14(1): 54

Metformin can mitigate skeletal dysplasia caused by Pck2 deficiency.

Zheng Li, Muxin Yue, Boon Chin Heng, Yunsong Liu, Ping Zhang, Yongsheng Zhou.

As an important enzyme for gluconeogenesis, mitochondrial phosphoenolpyruvate carboxykinase (PCK2) has further complex functions beyond regulation of glucose metabolism. Here, we report that conditional knockout of Pck2 in osteoblasts results in a pathological phenotype manifested as craniofacial malformation, long bone loss, and marrow adipocyte accumulation. Ablation of Pck2 alters the metabolic pathways of developing bone, particularly fatty acid metabolism. However, metformin treatment can mitigate skeletal dysplasia of embryonic and postnatal heterozygous knockout mice, at least partly via the AMPK signaling pathway. Collectively, these data illustrate that PCK2 is pivotal for bone development and metabolic homeostasis, and suggest that regulation of metformin-mediated signaling could provide a novel and practical strategy for treating metabolic skeletal dysfunction.

DOI: https://doi.org/10.1038/s41368-022-00204-1
Cell Metab. 2022 Nov 08. pii: S1550-4131(22)00489-2. [Epub ahead of print]

Ribosome stalling is a signal for metabolic regulation by the ribotoxic stress response.

Goda Snieckute, Aitana Victoria Genzor, Anna Constance Vind, Laura Ryder, Mark Stoneley, Sébastien Chamois, René Dreos, Cathrine Nordgaard, Frederike Sass, Melanie Blasius, Aida Rodríguez López, Sólveig Hlín Brynjólfsdóttir, Kasper Langebjerg Andersen, Anne E Willis, Lisa B Frankel, Steen Seier Poulsen, David Gatfield, Zachary Gerhart-Hines, Christoffer Clemmensen, Simon Bekker-Jensen.

  Impairment of translation can lead to collisions of ribosomes, which constitute an activation platform for several ribosomal stress-surveillance pathways. Among these is the ribotoxic stress response (RSR), where ribosomal sensing by the MAP3K ZAKα leads to activation of p38 and JNK kinases. Despite these insights, the physiological ramifications of ribosomal impairment and downstream RSR signaling remain elusive. Here, we show that stalling of ribosomes is sufficient to activate ZAKα. In response to amino acid deprivation and full nutrient starvation, RSR impacts on the ensuing metabolic responses in cells, nematodes, and mice. The RSR-regulated responses in these model systems include regulation of AMPK and mTOR signaling, survival under starvation conditions, stress hormone production, and regulation of blood sugar control. In addition, ZAK-/- male mice present a lean phenotype. Our work highlights impaired ribosomes as metabolic signals and demonstrates a role for RSR signaling in metabolic regulation.

Keywords:  AMPK; FGF21; ZAK-alpha; amino acid starvation; mTOR; metabolic regulation; mouse models; ribosome collision; ribotoxic stress response

DOI:  https://doi.org/10.1016/j.cmet.2022.10.011
J Gastrointest Oncol. 2022 Oct;13(5): 2458-2471

STING promotes proliferation and induces drug resistance in colorectal cancer by regulating the AMPK-mTOR pathway.

Huihui Yao, Suo Wang, Xin Zhou, Jinbing Sun, Guoqiang Zhou, Diyuan Zhou, Guoliang Chen, Xinyu Shi, Junjie Chen, Bo Shi, Qingliang Tai, Xiuwei Mi, Liang Sun, Yizhou Yao, Songbing He.

  Background: In recent years, reports regarding stimulator of interferon genes (STING) and the progression of colorectal cancer (CRC) have emerged rapidly, yet their association remains controversial. This research was aimed to provide an insight into the prognostic biomarker and therapeutic target significance of STING in CRC.Methods: CRC Cell lines of HCT116 and SW480, as well as 32 paired CRC specimens were chosen for this study. STING expressions were examined by immunohistochemistry to evaluate the correlation with clinicopathological factors. Data analysis of STING expressions in colon cancer and rectal cancer were performed using The Cancer Genome Atlas (TCGA) database. siRNA was transfected into cell lines for knocking down the expression of STING. Transwell assay was employed to evaluate cell migration and invasiveness. CCK-8 assay was used for assessing the change of cell proliferation. Drug sensitive test was involved to evaluate drug resistance of cell lines. Gene Set Enrichment Analysis (GSEA) was applied for exploring potential downstream mechanism of STING in CRC progression and Western blotting is used for mechanism validation.
Results: In the thirty-two paired CRC and adjacent normal tissues, we found a significant up-regulated in STING expression with immunohistochemical staining in cancer tissues compared with adjacent normal tissues (P<0.01), which was correlated with the tumor-node-metastasis (TNM) stage of patients (P=0.028). Meanwhile, GESA enrichment analysis indicated a remarkable change in mTOR signaling following STING regulation. In HCT116 and SW480 cell lines of CRC, When STING was down-regulated, its biological behavior of cell viability, cell invasion and drug sensitivity to 5-fluorouracil were significantly reduced (P<0.05), we also observed the up-regulation of P-AMPK (P<0.05) and down-regulation of p-mTOR (P<0.05).
Conclusions: STING expressions was significantly up-regulated in CRC tissues. Expression of STING was correlated with the TNM stage of patients. STING is found to promote cell proliferation, invasion ability and drug resistance mediating AMPK-mTOR signaling in CRC. STING could be a promising target for the sensitization of chemotherapy and inhibits CRC progression.

Keywords:  Colorectal cancer (CRC); clinicopathological features; drug resistance; proliferation; stimulator of interferon genes (STING)

DOI:  https://doi.org/10.21037/jgo-22-957
Cell Immunol. 2022 Nov 10. pii: S0008-8749(22)00164-2. [Epub ahead of print]382 104639

AMPK activator AICAR in combination with anti-mouse IL10 mAb restores the functionality of intra-tumoral Tfh cells in the 4T1 mouse model.

Poulomi Khamaru, Sayan Chakraborty, Arindam Bhattacharyya.

  4T1 cell-mediated TNBC breast cell carcinoma is a highly malignant mice tumor model which resembles an advanced stage of breast cancer in humans. Tumor progression occurs depending on the intra-tumoral balance of pro- and anti- tumorigenic immune cells. Enhancement of T-cell-mediated anti-tumor immunity will be advantageous for inhibiting tumor progression and improving the efficacy of cancer therapy. This study is focused on alleviating suppressed anti-tumor immune response by improving CD4+ T follicular helper cell (Tfh) response in 4T1 mice. We employed anti-IL10 mAb along with metabolic drugs 2-deoxy-D-glucose (2DG) which inhibits the glycolytic pathway and Cpt1a inhibitor Etomoxir which inhibits FAO. AMPK activator AICAR with or without anti-IL10 mAb was also used to ameliorate metabolic stress and exhaustion faced by immune cells. Our results demonstrate that synergistic treatment with 2DG/Etomoxir + anti-IL10 mAb induced Tfh cell, memory B, and GC B cell response more potently compared to treatment with 2DG or Etomoxir treatment alone as observed in several LNs and tumor tissue of 4T1 mouse. However, AICAR + anti-IL10 mAb increased the frequency of intratumoral Tfh cells, simultaneously downregulated Tfr cells; and improved humoral response by stimulating upregulation of memory B, GC B, and plasmablasts in tumor-draining, axillary, and mesenteric LNs of 4T1 mouse.

Keywords:  4T1 metastatic tumor; Anti-IL10 mAb; B cell; Breast tumor; Metabolic drug; T follicular helper cell; T regulatory cell; Tumor draining lymph node (TDLN)

DOI:  https://doi.org/10.1016/j.cellimm.2022.104639
Mol Cell Biochem. 2022 Nov 16.

Luteoloside pretreatment attenuates anoxia-induced damage in cardiomyocytes by regulating autophagy mediated by 14-3-3η and the AMPKα-mTOR/ULK1 pathway.

Tianhong Hu, Lin Wen, Liang Wang, Yang Qiao, Xie Cheng, Qigui Fan, Songqing Lai, Huan He, Ming He.

  The relation between ischemia and heart failure is well demonstrated, and several studies suggested that realizing the physiological role of autophagy will be of great importance. Luteoloside (Lut) is one of the main components of Lonicera japonica flos and exhibits antioxidant, anti-inflammatory, and cardioprotective properties. To determine if Lut pretreatment enhanced autophagy by 14-3-3η expression and the AMPKα-mTOR/ULK1 pathway and protected the neonatal rat cardiomyocytes (NRCMs) against anoxia damage, NRCMs were treated using 20 μM Lut for 36 h, and the anoxia damage model was established using NRCMs. The indexes reflecting the condition of NRCMs, oxidative stress level, and mitochondrial function were evaluated. In addition, the expression and phosphorylation of 14-3-3η and AMPKα/mTOR/ULK1, and autophagy markers (LC3II, P62) and the abundance of autophagy lysosomes were detected. Results revealed that Lut pretreatment alleviated anoxia- induced damage in NRCMs, that is, Lut pretreatment could increase cell viability, decrease LDH activity and apoptosis, suppressed ROS generation and oxidative stress, restored intracellular ATP levels, stabilized MMP levels, and inhibited mPTP opening. Furthermore, Lut pretreatment could enhance autophagy via upregulating 14-3-3η, LC3II expression and increasing p-AMPKα/AMPKα and p-ULK1/ULK1 level, whereas P62 expression and p-mTOR/mTOR level decreased; the fluorescence intensity of autolysosomes also increased. However, in the NRCMs treated with pAD/14-3-3η RNAi or incubated with 3-MA (an autophagy inhibitor), the abovementioned effects of Lut pretreatment were reduced. Taken together, Lut pretreatment could enhance autophagy by upregulating 14-3-3η expression to influence the AMPKα-mTOR/ ULK1 pathway against anoxia-induced damage in NRCMs.

Keywords:  14-3-3η; AMPKα-mTOR/ULK1 pathway; Anoxia damage; Autophagy; Cardiomyocytes; Luteoloside

DOI:  https://doi.org/10.1007/s11010-022-04611-0