bims-amsmem 2022-11-27 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2022–11–27
23 papers selected by
Dipsikha Biswas, Københavns Universitet

AMPK induces degradation of the transcriptional repressor PROX1 impairing branched amino acid metabolism and tumourigenesis.
Zika virus infection triggers lipophagy by stimulating the AMPK-ULK1 signaling in human hepatoma cells.
Identification of novel benzimidazole derivatives as highly potent AMPK activators with anti-diabetic profiles.
OXPHOS deficiency induces mitochondrial DNA synthesis through non-canonical AMPK-dependent mRNA compartmentalization.
Nutrient-sensing mTORC1 and AMPK pathways in chronic kidney diseases.
Transient Ca2+ entry by plasmalogen-mediated activation of receptor potential cation channel promotes AMPK activity.
circPRKAA1 activates a Ku80/Ku70/SREBP-1 axis driving de novo fatty acid synthesis in cancer cells.
The phosphorylation of AMPKβ1 is critical for increasing autophagy and maintaining mitochondrial homeostasis in response to fatty acids.
Mitophagy bridges DNA sensing with metabolic adaption to expand lung cancer stem-like cells.
Mechanistic insights on impact of Adenosine monophosphate-activated protein kinase (AMPK) mediated signalling pathways on cerebral ischemic injury.
Metformin Suppresses SARS-CoV-2 in Cell Culture.
Lactate Activates AMPK Remodeling of the Cellular Metabolic Profile and Promotes the Proliferation and Differentiation of C2C12 Myoblasts.
Coordination of AMPK and YAP by Spatholobi Caulis and Procyanidin B2 Provides Antioxidant Effects In Vitro and In Vivo.
Myostatin Knockout Affects Mitochondrial Function by Inhibiting the AMPK/SIRT1/PGC1α Pathway in Skeletal Muscle.
Survival Pathways of HIF-Deficient Tumour Cells: TCA Inhibition, Peroxisomal Fatty Acid Oxidation Activation and an AMPK-PGC-1α Hypoxia Sensor.
Small extracellular vesicle targeting of hypothalamic AMPKα1 promotes weight loss in leptin receptor deficient mice.
FABP5 Deficiency Impaired Macrophage Inflammation by Regulating AMPK/NF-κB Signaling Pathway.
Involvement of AMPKα and MAPK-ERK/-JNK Signals in Docetaxel-Induced Human Tongue Squamous Cell Carcinoma Cell Apoptosis.
DJ-1 activates the AMPK/mTOR pathway by binding RACK1 to induce autophagy and protect the myocardium from ischemia/hypoxia injury.
AdipoRon Inhibits Neuroinflammation Induced by Deep Hypothermic Circulatory Arrest Involving the AMPK/NF-κB Pathway in Rats.
Plasma exosomal miR-122 regulates the efficacy of metformin via AMPK in type 2 diabetes and hepatocellular carcinoma.
VH-4-A Bioactive Peptide from Soybean and Exercise Training Constrict Hypertension in Rats through Activating Cell Survival and AMPKα1, Sirt1, PGC1α, and FoX3α.
AMPK/mTOR Pathway Is Involved in Autophagy Induced by Magnesium-Incorporated TiO2 Surface to Promote BMSC Osteogenic Differentiation.

Nat Commun. 2022 Nov 24. 13(1): 7215

AMPK induces degradation of the transcriptional repressor PROX1 impairing branched amino acid metabolism and tumourigenesis.

Yanan Wang, Mengjun Luo, Fan Wang, Yu Tong, Linfeng Li, Yu Shu, Ke Qiao, Lei Zhang, Guoquan Yan, Jing Liu, Hongbin Ji, Youhua Xie, Yonglong Zhang, Wei-Qiang Gao, Yanfeng Liu.

Tumour cell metabolic plasticity is essential for tumour progression and therapeutic responses, yet the underlying mechanisms remain poorly understood. Here, we identify Prospero-related homeobox 1 (PROX1) as a crucial factor for tumour metabolic plasticity. Notably, PROX1 is reduced by glucose starvation or AMP-activated protein kinase (AMPK) activation and is elevated in liver kinase B1 (LKB1)-deficient tumours. Furthermore, the Ser79 phosphorylation of PROX1 by AMPK enhances the recruitment of CUL4-DDB1 ubiquitin ligase to promote PROX1 degradation. Downregulation of PROX1 activates branched-chain amino acids (BCAA) degradation through mediating epigenetic modifications and inhibits mammalian target-of-rapamycin (mTOR) signalling. Importantly, PROX1 deficiency or Ser79 phosphorylation in liver tumour shows therapeutic resistance to metformin. Clinically, the AMPK-PROX1 axis in human cancers is important for patient clinical outcomes. Collectively, our results demonstrate that deficiency of the LKB1-AMPK axis in cancers reactivates PROX1 to sustain intracellular BCAA pools, resulting in enhanced mTOR signalling, and facilitating tumourigenesis and aggressiveness.

DOI: https://doi.org/10.1038/s41467-022-34747-y
Front Cell Infect Microbiol. 2022 ;12 959029

Zika virus infection triggers lipophagy by stimulating the AMPK-ULK1 signaling in human hepatoma cells.

Zhao-Ling Qin, Qiu-Feng Yao, Ping Zhao, Hao Ren, Zhong-Tian Qi.

  Zika virus (ZIKV) is a globally transmitted mosquito-borne pathogen, and no effective treatment or vaccine is available yet. Lipophagy, a selective autophagy targeting lipid droplets (LDs), is an emerging subject in cellular lipid metabolism and energy homeostasis. However, the regulatory mechanism of lipid metabolism and the role of lipophagy in Zika virus infection remain largely unknown. Here, we demonstrated that ZIKV induced lipophagy by activating unc-51-like kinase 1 (ULK1) through activation of 5' adenosine monophosphate (AMP)-activated protein kinase (AMPK) in Huh7 cells. Upon ZIKV infection, the average size and triglyceride content of LDs significantly decreased. Moreover, ZIKV infection significantly increased lysosomal biosynthesis and LD-lysosome fusion. The activities of AMPK at Thr-172 and ULK1 at Ser-556 were increased in ZIKV-infected cells and closely correlated with lipophagy induction. Silencing of AMPK expression inhibited ZIKV infection, autophagy induction, and LD-lysosome fusion and decreased the triglyceride content of the cells. The activities of mammalian target of rapamycin (mTOR) at Ser-2448 and ULK1 at Ser-757 were suppressed independently of AMPK during ZIKV infection. Therefore, ZIKV infection triggers AMPK-mediated lipophagy, and the LD-related lipid metabolism during ZIKV infection is mainly regulated via the AMPK-ULK1 signaling pathway.

Keywords:  AMPK; ULK1; Zika virus; lipid metabolism; lipophagy; mTOR

DOI:  https://doi.org/10.3389/fcimb.2022.959029
Bioorg Med Chem Lett. 2022 Nov 16. pii: S0960-894X(22)00535-2. [Epub ahead of print] 129059

Identification of novel benzimidazole derivatives as highly potent AMPK activators with anti-diabetic profiles.

Yuusuke Tamura, Ippei Morita, Yu Hinata, Eiichi Kojima, Yoshikazu Sasaki, Toshihiro Wada, Mutsumi Asano, Masahiko Fujioka, Yoko Hayasaki-Kajiwara, Takanori Iwasaki, Kenichi Matsumura.

  Diabetes is a global healthcare problem that affects more than 400 million people worldwide. Treatment for type 1 and 2 diabetes is expected by targeting adenosine monophosphate activated protein kinase, AMPK, a well-known master regulator of glucose. Many pharmaceutical companies have tried to identify AMPK activators but few direct AMPK activators with high potency for the β2-AMPK isoform, which is important for glucose homeostasis, have been found. In addition, their chemical structure is limited to benzimidazole or indole derivatives bearing an aromatic substituent at the C5 position of the core structure. We describe herein our efforts to identify novel benzimidazole derivatives that directly activate the β2-AMPK isoform. Our newly designed activator 14d bearing a 1-amino indanyl moiety at the C5 position of the core exhibited high in vitro potency and good pharmacokinetic profiles. A single oral dosing of 14d showed dose-dependent activation of AMPK and blood-glucose-lowering effects was observed in a diabetic animal model. In addition, chronic AMPK activation with 14d led to dose-dependent reduction in HbA1c of the animal model.

Keywords:  AMPK activator; Benzimidazole; Type 2 diabetes

DOI:  https://doi.org/10.1016/j.bmcl.2022.129059
J Biosci. 2022 ;pii: 67. [Epub ahead of print]47

OXPHOS deficiency induces mitochondrial DNA synthesis through non-canonical AMPK-dependent mRNA compartmentalization.

Milon Banik, Samit Adhya.

Eukaryotic cells contain multiple copies of mitochondrial DNA (mtDNA) in discrete organelles or as tubular networks throughout the cytoplasm. The mtDNA copy number is dynamically regulated by mitochondrial biogenesis and mitophagy processes. However, the conditions regulating mtDNA replication, an essential component of biogenesis, are unknown. We observed that short-term (2 h) treatment of rat myoblasts with oligomycin, a specific inhibitor of the mitochondrial F1F0 ATP synthase, resulted in stimulation of mtDNA synthesis from the OH replication origin. This effect was abrogated by Compound C, an antagonist of the AMP-dependent protein kinase (AMPK), a universal intracellular energy sensor, and in AMPK-knockdown cells, indicating that mtDNA replication is regulated by AMPK under oxidative phosphorylation (OXPHOS)- deficient conditions. Using antibody decoration, enzymatically active AMPK, phosphorylated at T172 of the α1 subunit, was found to be located on the mitochondrial surface. Furthermore, oligomycin induced the compartmentalization of several mRNAs encoding OXPHOS components and mtDNA replication factors to mitochondria. Compartmentalization of mRNAs was inhibited by Compound C. We infer that AMPK is locally activated by inhibition of the F1F0 ATP synthase to stimulate association of mtDNA replication factor mRNAs, leading to stimulation of mtDNA synthesis. The findings have implications for the clonal expansion of OXPHOS-deficient mtDNA mutant mitochondria in human patients, with clinical consequences.
Nat Rev Nephrol. 2022 Nov 24.

Nutrient-sensing mTORC1 and AMPK pathways in chronic kidney diseases.

Christopher Huynh, Jaewhee Ryu, Jooho Lee, Ayaka Inoki, Ken Inoki.

Nutrients such as glucose, amino acids and lipids are fundamental sources for the maintenance of essential cellular processes and homeostasis in all organisms. The nutrient-sensing kinases mechanistic target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) are expressed in many cell types and have key roles in the control of cell growth, proliferation, differentiation, metabolism and survival, ultimately contributing to the physiological development and functions of various organs, including the kidney. Dysregulation of these kinases leads to many human health problems, including cancer, neurodegenerative diseases, metabolic disorders and kidney diseases. In the kidney, physiological levels of mTOR and AMPK activity are required to support kidney cell growth and differentiation and to maintain kidney cell integrity and normal nephron function, including transport of electrolytes, water and glucose. mTOR forms two functional multi-protein kinase complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Hyperactivation of mTORC1 leads to podocyte and tubular cell dysfunction and vulnerability to injury, thereby contributing to the development of chronic kidney diseases, including diabetic kidney disease, obesity-related kidney disease and polycystic kidney disease. Emerging evidence suggests that targeting mTOR and/or AMPK could be an effective therapeutic approach to controlling or preventing these diseases.

DOI: https://doi.org/10.1038/s41581-022-00648-y
Front Mol Biosci. 2022 ;9 1008626

Transient Ca2+ entry by plasmalogen-mediated activation of receptor potential cation channel promotes AMPK activity.

Masanori Honsho, Shiro Mawatari, Takehiko Fujino.

  Ethanolamine-containing alkenyl ether glycerophospholipids, plasmalogens, are major cell membrane components of mammalian cells that activate membrane protein receptors such as ion transporters and G-protein coupled receptors. However, the mechanism by which plasmalogens modulate receptor function is unknown. Here, we found that exogenously added plasmalogens activate transient receptor potential cation channel subfamily C member 4 (TRPC4) to increase Ca2+ influx, followed by calcium/calmodulin-dependent protein kinase 2-mediated phosphorylation of AMP-activated protein kinase (AMPK). Upon topical application of plasmalogens to the skin of mice, AMPK activation was observed in TRPC4-expressing hair bulbs and hair follicles. Here, TRPC4 was co-localized with the leucine-rich repeat containing G protein-coupled receptor 5, a marker of hair-follicle stem cells, leading to hair growth. Collectively, this study indicates that plasmalogens could function as gate openers for TRPC4, followed by activating AMPK, which likely accelerates hair growth in mice.

Keywords:  AMPK; Ca2+; TRPC4; hair bulb; hair follicle; hair growth; plasmalogens

DOI:  https://doi.org/10.3389/fmolb.2022.1008626
Cell Rep. 2022 Nov 22. pii: S2211-1247(22)01581-9. [Epub ahead of print]41(8): 111707

circPRKAA1 activates a Ku80/Ku70/SREBP-1 axis driving de novo fatty acid synthesis in cancer cells.

Qidong Li, Hanhui Yao, Yichun Wang, Yang Wu, Rick F Thorne, Youming Zhu, Mian Wu, Lianxin Liu.

  Many metabolism-related genes undergo alternative splicing to generate circular RNAs, but their functions remain poorly understood. Here we report that circPRKAA1, a circular RNA (circRNA) derived from the α1 subunit of AMP-activated protein kinase (AMPK), fulfills a fundamental role in maintaining lipid homeostasis. circPRKAA1 expression facilitates fatty acid synthesis and promotes lipid storage through two coordinated functions. First, circPRKAA1 promotes a tetrameric complex between the Ku80/Ku70 heterodimer and the mature form of sterol regulatory element-binding protein 1 (mSREBP-1) to enhance the stability of mSREBP-1. Second, circPRKAA1 selectively binds to the promoters of the ACC1, ACLY, SCD1, and FASN genes to recruit mSREBP-1, upregulating their transcription and increasing fatty acid synthesis to promote cancer growth. circPRKAA1 biogenesis is negatively regulated by AMPK activity, with lower AMPK activation in hepatocellular carcinoma tissue frequently associated with elevated circPRKAA1 expression. This work identifies circPRKAA1 as an integral element of AMPK-regulated reprogramming of lipid metabolism in cancer cells.

Keywords:  AMPK; CP: Cancer; CP: Metabolism; Ku80/Ku70; SREBP-1; SRSF1; circPRKAA1; fatty acid synthesis

DOI:  https://doi.org/10.1016/j.celrep.2022.111707
Proc Natl Acad Sci U S A. 2022 Nov 29. 119(48): e2119824119

The phosphorylation of AMPKβ1 is critical for increasing autophagy and maintaining mitochondrial homeostasis in response to fatty acids.

Eric M Desjardins, Brennan K Smith, Emily A Day, Serge Ducommun, Matthew J Sanders, Joshua P Nederveen, Rebecca J Ford, Stephen L Pinkosky, Logan K Townsend, Robert M Gutgesell, Rachel Lu, Kei Sakamoto, Gregory R Steinberg.

  Fatty acids are vital for the survival of eukaryotes, but when present in excess can have deleterious consequences. The AMP-activated protein kinase (AMPK) is an important regulator of multiple branches of metabolism. Studies in purified enzyme preparations and cultured cells have shown that AMPK is allosterically activated by small molecules as well as fatty acyl-CoAs through a mechanism involving Ser108 within the regulatory AMPK β1 isoform. However, the in vivo physiological significance of this residue has not been evaluated. In the current study, we generated mice with a targeted germline knock-in (KI) mutation of AMPKβ1 Ser108 to Ala (S108A-KI), which renders the site phospho-deficient. S108A-KI mice had reduced AMPK activity (50 to 75%) in the liver but not in the skeletal muscle. On a chow diet, S108A-KI mice had impairments in exogenous lipid-induced fatty acid oxidation. Studies in mice fed a high-fat diet found that S108A-KI mice had a tendency for greater glucose intolerance and elevated liver triglycerides. Consistent with increased liver triglycerides, livers of S108A-KI mice had reductions in mitochondrial content and respiration that were accompanied by enlarged mitochondria, suggestive of impairments in mitophagy. Subsequent studies in primary hepatocytes found that S108A-KI mice had reductions in palmitate- stimulated Cpt1a and Ppargc1a mRNA, ULK1 phosphorylation and autophagic/mitophagic flux. These data demonstrate an important physiological role of AMPKβ1 Ser108 phosphorylation in promoting fatty acid oxidation, mitochondrial biogenesis and autophagy under conditions of high lipid availability. As both ketogenic diets and intermittent fasting increase circulating free fatty acid levels, AMPK activity, mitochondrial biogenesis, and mitophagy, these data suggest a potential unifying mechanism which may be important in mediating these effects.

Keywords:  AMPK; NAFLD; autophagy; fat oxidation; mitochondria

DOI:  https://doi.org/10.1073/pnas.2119824119
EMBO Rep. 2022 Nov 23. e54006

Mitophagy bridges DNA sensing with metabolic adaption to expand lung cancer stem-like cells.

Zhen Liu, Shan Shan, Zixin Yuan, Fengying Wu, Ming Zheng, Ying Wang, Jun Gui, Wei Xu, Chunhong Wang, Tao Ren, Zhenke Wen.

  While previous studies have identified cancer stem-like cells (CSCs) as a crucial driver for chemoresistance and tumor recurrence, the underlying mechanisms for populating the CSC pool remain unclear. Here, we identify hypermitophagy as a feature of human lung CSCs, promoting metabolic adaption via the Notch1-AMPK axis to drive CSC expansion. Specifically, mitophagy is highly active in CSCs, resulting in increased mitochondrial DNA (mtDNA) content in the lysosome. Lysosomal mtDNA acts as an endogenous ligand for Toll-like receptor 9 (TLR9) that promotes Notch1 activity. Notch1 interacts with AMPK to drive lysosomal AMPK activation by inducing metabolic stress and LKB1 phosphorylation. This TLR9-Notch1-AMPK axis supports mitochondrial metabolism to fuel CSC expansion. In patient-derived xenograft chimeras, targeting mitophagy and TLR9-dependent Notch1-AMPK pathway restricts tumor growth and CSC expansion. Taken together, mitochondrial hemostasis is interlinked with innate immune sensing and Notch1-AMPK activity to increase the CSC pool of human lung cancer.

Keywords:  AMPK; Notch1; TLR9; cancer stem-like cell; mitophagy

DOI:  https://doi.org/10.15252/embr.202154006
Neurosci Res. 2022 Nov 17. pii: S0168-0102(22)00286-3. [Epub ahead of print]

Mechanistic insights on impact of Adenosine monophosphate-activated protein kinase (AMPK) mediated signalling pathways on cerebral ischemic injury.

Palak Kalra, Heena Khan, Thakur Gurjeet Singh, Amarjot Kaur Grewal.

  Cerebral ischemia is the primary cause of morbidity and mortality worldwide due to the perturbations in the blood supply to the brain. The brain triggers a cascade of complex metabolic and cellular defects in response to ischemic stress. However, due to the disease heterogeneity and complexity, ischemic injury's metabolic and cellular pathologies remain elusive, and the link between various pathological mechanisms is difficult to determine. Efforts to develop effective treatments for these disorders have yielded limited efficacy, with no proper cure available to date. Recent clinical and experimental research indicates that several neuronal diseases commonly coexist with metabolic dysfunction, which may aggravate neurological symptoms. As a result, it stands to a reason that metabolic hormones could be a potential therapeutic target for major NDDs. Moreover, fasting signals also influence the circadian clock, as AMPK phosphorylates and promotes the degradation of the photo-sensing receptor (cryptochrome). Here, the interplay of AMPK signaling between metabolic regulation and neuronal death and its role for pathogenesis and therapeutics has been studied. We have also highlighted a significant signaling pathway, i.e., the adenosine monophosphate-activated protein kinase (AMPK) involved in the relationship between the metabolism and ischemia, which could be used as a target for future studies therapeutics, and review some of the clinical progress in this area.

Keywords:  Adenosine monophosphate-activated protein kinase; Adiponectin; Ghrelin; Insulin; Ischemia; Leptin; Neuroprotection; metabolic

DOI:  https://doi.org/10.1016/j.neures.2022.11.006
Virus Res. 2022 Nov 20. pii: S0168-1702(22)00339-2. [Epub ahead of print] 199010

Metformin Suppresses SARS-CoV-2 in Cell Culture.

Haripriya Parthasarathy, Dixit Tandel, Abdul Hamid Siddiqui, Krishnan H Harshan.

  Comorbidities such as diabetes worsen COVID-19 severity and recovery. Metformin, a first-line medication for type 2 diabetes, has antiviral properties and certain studies have also indicated its prognostic potential in COVID-19. Here, we report that metformin significantly inhibits SARS-CoV-2 growth in cell culture models. First, a steady increase in AMPK phosphorylation was detected as infection progressed, suggesting its important role during viral infection. Activation of AMPK in Calu3 and Caco2 cell lines using metformin revealed that metformin suppresses SARS-CoV-2 infectious titers up to 99%, in both naïve as well as infected cells. IC50 values from dose-variation studies in infected cells were found to be 0.4 and 1.43 mM in Calu3 and Caco2 cells, respectively. Role of AMPK in metformin's antiviral suppression was further confirmed using other pharmacological compounds, AICAR and Compound C. Collectively, our study demonstrates that metformin is effective in limiting the replication of SARS-CoV-2 in cell culture and thus possibly could offer double benefits as diabetic COVID-19 patients by lowering both blood glucose levels and viral load.

Keywords:  AMPK; COVID-19; Diabetes; Metformin; SARS-CoV-2; antiviral activity

DOI:  https://doi.org/10.1016/j.virusres.2022.199010
Int J Mol Sci. 2022 Nov 13. pii: 13996. [Epub ahead of print]23(22):

Lactate Activates AMPK Remodeling of the Cellular Metabolic Profile and Promotes the Proliferation and Differentiation of C2C12 Myoblasts.

Yu Zhou, Xi Liu, Caihua Huang, Donghai Lin.

  Lactate is a general compound fuel serving as the fulcrum of metabolism, which is produced from glycolysis and shuttles between different cells, tissues and organs. Lactate is usually accumulated abundantly in muscles during exercise. It remains unclear whether lactate plays an important role in the metabolism of muscle cells. In this research, we assessed the effects of lactate on myoblasts and clarified the underlying metabolic mechanisms through NMR-based metabonomic profiling. Lactate treatment promoted the proliferation and differentiation of myoblasts, as indicated by significantly enhanced expression levels of the proteins related to cellular proliferation and differentiation, including p-AKT, p-ERK, MyoD and myogenin. Moreover, lactate treatment profoundly regulated metabolisms in myoblasts by promoting the intake and intracellular utilization of lactate, activating the TCA cycle, and thereby increasing energy production. For the first time, we found that lactate treatment evidently promotes AMPK signaling as reflected by the elevated expression levels of p-AMPK and p-ACC. Our results showed that lactate as a metabolic regulator activates AMPK, remodeling the cellular metabolic profile, and thereby promoting the proliferation and differentiation of myoblasts. This study elucidates molecular mechanisms underlying the effects of lactate on skeletal muscle in vitro and may be of benefit to the exploration of lactate acting as a metabolic regulator.

Keywords:  AMPK; C2C12 myoblasts; NMR-based metabonomics; lactate; metabolic regulator

DOI:  https://doi.org/10.3390/ijms232213996
Int J Mol Sci. 2022 Nov 08. pii: 13730. [Epub ahead of print]23(22):

Coordination of AMPK and YAP by Spatholobi Caulis and Procyanidin B2 Provides Antioxidant Effects In Vitro and In Vivo.

Su-Jin Bae, Seon Been Bak, Young Woo Kim.

  The liver is vulnerable to oxidative attacks from heavy metals, such as iron, as well as some drugs, including acetaminophen. It has been shown that enhanced oxidative stress in the liver leads to excessive ROS production and mitochondrial dysfunction, resulting in organ injury. The beneficial effects of Spatholobi Caulis (SC), a natural herbal medicine, include treating ischemic stroke, inhibiting tumor cell invasion, pro-angiogenic activities, and anti-inflammatory properties. Scientific studies on its effects against hepatotoxic reagents (e.g., iron and acetaminophen), as well as their underlying mechanisms, are insufficient. This study examined the antioxidant effects and mechanisms of SC in vitro and in vivo. In cells, the proinflammatory mediator, arachidonic acid (AA), plus iron, significantly induced an increase in ROS generation, the damage in mitochondrial membrane potential, and the resulting apoptosis, which were markedly blocked by SC. More importantly, SC affected the activation of AMP-activated protein kinase (AMPK)-related proteins, which were vital to regulating oxidative stress in cells. In addition, SC mediated the expression of Yes-associated protein (YAP)-related proteins. Among the active compounds in SC, the procyanidin B2, but not liquiritigenin, daidzein, and genistein, significantly inhibited the cytotoxicity induced by AA + iron, and activated the LKB1-AMPK pathway. In mice, the oral administration of SC alleviated the elevations of ALT and histological changes by the acetaminophen-induced liver injury. These results reveal the potential of SC and a key bioactive component, procyanidin B2, as antioxidant candidates for hepatoprotection.

Keywords:  AMPK; Spatholobi Caulis; YAP; acetaminophen; liver injury; procyanidin B2

DOI:  https://doi.org/10.3390/ijms232213730
Int J Mol Sci. 2022 Nov 08. pii: 13703. [Epub ahead of print]23(22):

Myostatin Knockout Affects Mitochondrial Function by Inhibiting the AMPK/SIRT1/PGC1α Pathway in Skeletal Muscle.

Mingjuan Gu, Zhuying Wei, Xueqiao Wang, Yang Gao, Dong Wang, Xuefei Liu, Chunling Bai, Guanghua Su, Lei Yang, Guangpeng Li.

  Myostatin (Mstn) is a major negative regulator of skeletal muscle mass and initiates multiple metabolic changes. The deletion of the Mstn gene in mice leads to reduced mitochondrial functions. However, the underlying regulatory mechanisms remain unclear. In this study, we used CRISPR/Cas9 to generate myostatin-knockout (Mstn-KO) mice via pronuclear microinjection. Mstn-KO mice exhibited significantly larger skeletal muscles. Meanwhile, Mstn knockout regulated the organ weights of mice. Moreover, we found that Mstn knockout reduced the basal metabolic rate, muscle adenosine triphosphate (ATP) synthesis, activities of mitochondrial respiration chain complexes, tricarboxylic acid cycle (TCA) cycle, and thermogenesis. Mechanistically, expressions of silent information regulator 1 (SIRT1) and phosphorylated adenosine monophosphate-activated protein kinase (pAMPK) were down-regulated, while peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) acetylation modification increased in the Mstn-KO mice. Skeletal muscle cells from Mstn-KO and WT were treated with AMPK activator 5-aminoimidazole-4-carboxamide riboside (AICAR), and the AMPK inhibitor Compound C, respectively. Compared with the wild-type (WT) group, Compound C treatment further down-regulated the expression or activity of pAMPK, SIRT1, citrate synthase (CS), isocitrate dehydrogenase (ICDHm), and α-ketoglutarate acid dehydrogenase (α-KGDH) in Mstn-KO mice, while Mstn knockout inhibited the AICAR activation effect. Therefore, Mstn knockout affects mitochondrial function by inhibiting the AMPK/SIRT1/PGC1α signaling pathway. The present study reveals a new mechanism for Mstn knockout in regulating energy homeostasis.

Keywords:  AMPK/SIRT1/PGC-1α; CRISPR/Cas9; knockout; mitochondrial; myostatin; skeletal muscle

DOI:  https://doi.org/10.3390/ijms232213703
Cells. 2022 Nov 14. pii: 3595. [Epub ahead of print]11(22):

Survival Pathways of HIF-Deficient Tumour Cells: TCA Inhibition, Peroxisomal Fatty Acid Oxidation Activation and an AMPK-PGC-1α Hypoxia Sensor.

Monika A Golinska, Marion Stubbs, Adrian L Harris, Laszlo G Boros, Madhu Basetti, Dominick J O McIntyre, John R Griffiths.

  The HIF-1 and HIF-2 (HIF1/2) hypoxia responses are frequently upregulated in cancers, and HIF1/2 inhibitors are being developed as anticancer drugs. How could cancers resist anti-HIF1/2 therapy? We studied metabolic and molecular adaptations of HIF-1β-deficient Hepa-1c4, a hepatoma model lacking HIF1/2 signalling, which mimics a cancer treated by a totally effective anti-HIF1/2 agent. [1,2-13C2]-D-glucose metabolism was measured by SiDMAP metabolic profiling, gene expression by TaqMan, and metabolite concentrations by 1H MRS. HIF-1β-deficient Hepa-1c4 responded to hypoxia by increasing glucose uptake and lactate production. They showed higher glutamate, pyruvate dehydrogenase, citrate shuttle, and malonyl-CoA fluxes than normal Hepa-1 cells, whereas pyruvate carboxylase, TCA, and anaplerotic fluxes decreased. Hypoxic HIF-1β-deficient Hepa-1c4 cells increased expression of PGC-1α, phospho-p38 MAPK, and PPARα, suggesting AMPK pathway activation to survive hypoxia. They had higher intracellular acetate, and secreted more H2O2, suggesting increased peroxisomal fatty acid β-oxidation. Simultaneously increased fatty acid synthesis and degradation would have "wasted" ATP in Hepa-1c4 cells, thus raising the [AMP]:[ATP] ratio, and further contributing to the upregulation of the AMPK pathway. Since these tumour cells can proliferate without the HIF-1/2 pathways, combinations of HIF1/2 inhibitors with PGC-1α or AMPK inhibitors should be explored.

Keywords:  1,2-13C2-labelled glucose; AMP-activated kinase; HIF-1β deficiency; Hepa-1 c4 cells; PGC-1α; PPARα; TCA; fatty acid oxidation; hypoxia response; phospho-p38 MAPK

DOI:  https://doi.org/10.3390/cells11223595
Metabolism. 2022 Nov 21. pii: S0026-0495(22)00228-1. [Epub ahead of print] 155350

Small extracellular vesicle targeting of hypothalamic AMPKα1 promotes weight loss in leptin receptor deficient mice.

Edward Milbank, Nathalia Dragano, Xavi Vidal-Gomez, Verónica Rivas-Limeres, Pablo Garrido-Gil, Mireille Wertheimer, Sylvain Recoquillon, María P Pata, José Luis Labandeira-Garcia, Carlos Diéguez, Rubén Nogueiras, M Carmen Martínez, Ramaroson Andriantsitohaina, Miguel López.

   BACKGROUND AND AIMS: Leptin receptor (LEPR) deficiency promotes severe obesity and metabolic disorder. However, the current therapeutic options against this syndrome are scarce.
METHODS: db/db mice and their wildtypes were systemically treated with neuronal-targeted small extracellular vesicles (sEVs) harboring a plasmid encoding a dominant negative mutant of AMP-activated protein kinase alpha 1 (AMPKα1-DN) driven by steroidogenic factor 1 (SF1) promoter; this approach allowed to modulate AMPK activity, specifically in SF1 cells of the ventromedial nucleus of the hypothalamus (VMH). Animals were metabolically phenotyped.
RESULTS: db/db mice intravenously injected with SF1-AMPKα1-DN loaded sEVs showed a marked feeding-independent weight loss and decreased adiposity, associated with increased sympathetic tone, brown adipose tissue (BAT) thermogenesis and browning of white adipose tissue (WAT).
CONCLUSION: Overall, this evidence indicates that specific modulation of hypothalamic AMPK using a sEV-based technology may be a suitable strategy against genetic forms of obesity, such as LEPR deficiency.

Keywords:  AMPK; Hypothalamus; Leptin receptor deficiency; db/db mice; sEVs

DOI:  https://doi.org/10.1016/j.metabol.2022.155350
J Immunol. 2022 Dec 01. 209(11): 2181-2191

FABP5 Deficiency Impaired Macrophage Inflammation by Regulating AMPK/NF-κB Signaling Pathway.

Yangxiao Hou, Dong Wei, Elhusseny A Bossila, Zhaoqi Zhang, Sihong Li, Jiaming Bao, Huawen Xu, Lianfeng Zhang, Yong Zhao.

Fatty acid binding protein 5 (FABP5) is mainly involved in the uptake, transport, and metabolism of fatty acid in the cytoplasm, and its role in immune cells has been recognized in recent years. However, the role of FABP5 in macrophage inflammation and its underlying mechanisms were not fully addressed. In our study, the acute liver injury and sepsis mouse models were induced by i.p. injection of LPS and cecal contents, respectively. Oleic acid (0.6 g/kg) was injected four times by intragastric administration every week, and this lasted for 1 wk before the LPS or cecal content challenge. We found that myeloid-specific deletion of FABP5 mitigated LPS-induced acute liver injury with reduced mortality of mice, histological liver damage, alanine aminotransferase, and proinflammatory factor levels. Metabolic analysis showed that FABP5 deletion increased the intracellular unsaturated fatty acids, especially oleic acid, in LPS-induced macrophages. The addition of oleic acid also decreased LPS-stimulated macrophage inflammation in vitro and reduced acute liver injury in LPS-induced or cecal content-induced sepsis mice. RNA-sequencing and molecular mechanism studies showed that FABP5 deletion or oleic acid supplementation increased the AMP/ATP ratio and AMP-activated protein kinase (AMPK) activation and inhibited the NF-κB pathway during the inflammatory response to LPS stimulation of macrophages. Inhibiting AMPK activation or expression by chemical or genetic approaches significantly rescued the decreased NF-κB signaling pathway and inflammatory response in LPS-treated FABP5-knockout macrophages. Our present study indicated that inhibiting FABP5 or supplementation of oleic acid might be used for the treatment of sepsis-caused acute liver injury.

DOI: https://doi.org/10.4049/jimmunol.2200182
Int J Mol Sci. 2022 Nov 10. pii: 13857. [Epub ahead of print]23(22):

Involvement of AMPKα and MAPK-ERK/-JNK Signals in Docetaxel-Induced Human Tongue Squamous Cell Carcinoma Cell Apoptosis.

Chin-Chuan Su, Jhe-Wei Lin, Kai-Yao Chang, Cheng-Tien Wu, Shing-Hwa Liu, Kai-Chih Chang, Jui-Ming Liu, Kuan-I Lee, Kai-Min Fang, Ya-Wen Chen.

  Cancers of the oral cavity can develop in the anatomic area extending from the lip, gum, tongue, mouth, and to the palate. Histologically, about 85-90% of oral cavity cancers are of the type squamous cells carcinomas (SCCs). The incidence of oral tongue SCC is higher in the tongue than any other anatomic area of the oral cavity. Here, we investigated the therapeutic effects and molecular mechanisms of docetaxel, which is a paclitaxel antitumor agent, on the cell growth of a human tongue SCC-derived SAS cell line. The results showed that docetaxel (10-300 nM) induced cytotoxicity and caspase-3 activity in SAS cells. Moreover, docetaxel (100 nM) promoted the expression of apoptosis-related signaling molecules, including the cleavages of caspase-3, caspase-7, and poly (ADP-ribose) polymerase (PARP). In mitochondria, docetaxel (100 nM) decreased the mitochondrial membrane potential (MMP) and Bcl-2 mRNA and protein expression and increased cytosolic cytochrome c protein expression and Bax mRNA and protein expression. In terms of mitogen-activated protein kinase (MAPK) and adenosine monophosphate-activated protein kinase (AMPK) signaling, docetaxel increased the expression of phosphorylated (p)-extracellular signal-regulated kinase (ERK), p-c-Jun N-terminal kinase (JNK), and p-AMPKα protein expression but not p-p38 protein expression. Moreover, the increase in caspase-3/-7 activity and Bax protein expression and decreased Bcl-2 protein expression and MMP depolarization observed in docetaxel-treated SAS cells could be reversed by treatment with either SP600125 (a JNK inhibitor), PD98059 (an MEK1/2 (mitogen-activated protein kinase kinase 1/2) inhibitor), or compound c (an AMPK inhibitor). The docetaxel-induced increases in p-JNK, p-ERK, and p-AMPKα protein expression could also be reversed by treatment with either SP600125, PD98059, or compound c. These results indicate that docetaxel induces human tongue SCC cell apoptosis via interdependent MAPK-JNK, MAPK-ERK1/2, and AMPKα signaling pathways. Our results show that docetaxel could possibly exert a potent pharmacological effect on human oral tongue SCC cell growth.

Keywords:  AMPKα; ERK; JNK; apoptosis; docetaxel; tongue squamous cells carcinomas

DOI:  https://doi.org/10.3390/ijms232213857
Biochem Biophys Res Commun. 2022 Nov 14. pii: S0006-291X(22)01519-4. [Epub ahead of print]637 276-285

DJ-1 activates the AMPK/mTOR pathway by binding RACK1 to induce autophagy and protect the myocardium from ischemia/hypoxia injury.

Xiao-Yan Zhao, Jian-Min Ren, Hui-Ru Liu, Ting-Ting Zhou, Xue-Ying Wang, Song Liu, He-Ping Chen.

  Myocardial Ischemic Injury is a serious threat to human health, and DJ-1 is involved in cardioprotection. The research intended to explore the effects and mechanism of DJ-1 to protect myocardium against ischemia injury. DJ-1 overexpression lentivirus vectors were transduced into the myocardium of SD rats and H9c2 cells, and an AMI model in vivo and a hypoxia model in vitro were established, respectively. Results showed that DJ-1 overexpression alleviated myocardial ischemia injury, as demonstrated by reduced the extent of myocardial infarction, improved cell survival, decreased LDH activity and CK-MB release. Furthermore, DJ-1 interacted with RACK1, activated AMPK/mTOR pathway, induced adaptive autophagy and protected the myocardium. However, RACK1 siRNA or compound C (an AMPK inhibitor) could weaken the above effect of DJ-1 on myocardium. In conclusion, DJ-1 could activate adaptive autophagy by the RACK1/AMPK/mTOR pathway and protect the myocardium against ischemia injury.

Keywords:  AMPK/mTOR; Autophagy; Cardioprotection; DJ-1

DOI:  https://doi.org/10.1016/j.bbrc.2022.10.100
Pharmaceutics. 2022 Nov 15. pii: 2467. [Epub ahead of print]14(11):

AdipoRon Inhibits Neuroinflammation Induced by Deep Hypothermic Circulatory Arrest Involving the AMPK/NF-κB Pathway in Rats.

Weidong Yan, Sizhe Gao, Qiaoni Zhang, Jiachen Qi, Gang Liu, Yuan Teng, Jian Wang, Shujie Yan, Bingyang Ji.

  Deep hypothermic circulatory arrest (DHCA) can induce systemic inflammatory response syndrome, including neuroinflammation. Finding suitable compounds is necessary for attenuating neuroinflammation and avoiding cerebral complications following DHCA. In the present study, we established DHCA rat models and monitored the vital signs during the surgical process. After surgery, we found significantly increased proinflammatory cytokines (IL-6, IL-1β, and TNF-α) in DHCA rats. Quantitative proteomics analysis was performed for exploring the differentially expressed proteins in hippocampus of DHCA rats and the data showed the adiponectin receptor 1 protein was upregulated. More importantly, administration of AdipoRon, a small-molecule adiponectin receptor agonist, could improve the basic vital signs and attenuate the increased IL-6, IL-1β, and TNF-α in DHCA rats. Furthermore, AdipoRon inhibits the activation of microglia (M1 state) and promotes their transition to an anti-inflammatory state, via promoting the phosphorylation of adenosine monophosphate-activated protein kinase (AMPK), and downregulating nuclear factor kappa B (NF-κB) in DHCA rats. Consistently, we used LPS-treated BV2 cells to mimic the neuroinflammatory condition and found that AdipoRon dose-dependently decreased cytokines, along with increased phosphorylation of AMPK and downregulated NF-κB. In conclusion, our present data supported that AdipoRon inhibited DHCA-induced neuroinflammation via activating the hippocampal AMPK/NF-κB pathway.

Keywords:  AdipoRon; deep hypothermic circulatory arrest; neuroinflammation

DOI:  https://doi.org/10.3390/pharmaceutics14112467
Heliyon. 2022 Nov;8(11): e11503

Plasma exosomal miR-122 regulates the efficacy of metformin via AMPK in type 2 diabetes and hepatocellular carcinoma.

Hui Peng, Mei Hou, Zixin Wu, Jing Wang, Man Zhou, Xiangjin Zhuang, Jiayu Xing, Qianqian Tao, Long Huang, Fuhai Zhou, Shengming Zhang, Qiyu Feng, Yilin Hou, Qinsheng Yu.

  Metformin is a drug that has been applied in clinical use for many years for the treatment of type 2 diabetes mellitus (T2DM). It achieves its function through multiple targets and modulation of multiple signaling pathways. To date, the mechanism of the action of metformin is still not fully understood. Along with glycemic control, metformin has shown good inhibitory effects on the development of many tumors. Here, we elucidated that plasma exosomal microRNA-122-5p (miR-122) is closely related to the mechanism of metformin. MiR-122 regulates glycogen-glucose metabolism in hepatocytes or hepatocellular carcinoma cells (HCC) by inhibiting the phosphorylation of AMPK. Since miR-122 and metformin regulate glucose metabolism homeostasis through similar mechanisms, miR-122 can antagonize the effects of metformin. MiR-122 expression increases the sensitivity of hepatocytes or HCC to metformin. Conversely, decreased expression of miR-122 results in hepatocyte insensitivity to metformin. Therefore, significantly elevated levels of miR-122 in plasma exosomes of hepatocellular carcinoma patients could enhance their sensitivity to metformin. The results of the present study revealed a key regulatory role of plasma exosomal miR-122 on the molecular mechanism of metformin. The regulation of key molecules of related signaling pathways by miR-122 may lead to similar glycemic lowering and tumor suppression therapeutic effects as metformin. This provides new ideas for the development of new therapeutic strategies for hepatocellular carcinoma based on the mechanism of miR-122 and metformin.

Keywords:  AMPK; Exosome; Hepatocellular carcinoma; Metformin; Type 2 diabetes; miR-122

DOI:  https://doi.org/10.1016/j.heliyon.2022.e11503
Molecules. 2022 Nov 09. pii: 7705. [Epub ahead of print]27(22):

VH-4-A Bioactive Peptide from Soybean and Exercise Training Constrict Hypertension in Rats through Activating Cell Survival and AMPKα1, Sirt1, PGC1α, and FoX3α.

Rathinasamy Baskaran, Balamuralikrishnan Balasubramanian, Jou-Hsuan Ho, Ming-Fu Wang, Mosleh Mohammad Abomughaid, Hong-Siang Yang, Wan-Teng Lin.

  Hypertension is a chronic disease related to age, which affects tens of millions of people around the world. It is an important risk factor that causes myocardial infarction, heart failure, stroke, and kidney damage. Bioactive peptide VHVV (VH-4) from soybean has shown several biological activities. Physical exercise is a cornerstone of non-pharmacologic treatment for hypertension and has established itself as an effective and complementary strategy for managing hypertension. The present study evaluates the efficacy of VH-4 supplement and swimming exercise training in preventing hypertension in spontaneously hypertensive rats (SHR). SHR animals were treated with VH-4 (25 mg/kg by intraperitoneal administration) and swimming exercise (1 h daily) for eight weeks, and the hemodynamic parameters, histology, and cell survival pathway protein expression were examined. In SHR rats, increased heart weight, blood pressure, and histological aberrations were observed. Cell survival protein p-PI3K and p-AKT and antiapoptosis proteins Bcl2 and Bcl-XL expression decreased in SHR animals. SIRT1 and FOXO3 were decreased in hypertensive rats. Both bioactive peptide VH-4 treatment and swimming exercise training in hypertensive rats increased the cell survival proteins p-PI3K and p-AKT and AMPKα1, Sirt1, PGC1α, and FoX3α proteins. Soy peptide VH-4, along with exercise, acts synergistically and prevents hypertension by activating cell survival and AMPKα1, Sirt1, PGC1α, and FoX3α proteins.

Keywords:  AMPK; hypertension; soybean peptides; spontaneous hypertension rats; swimming exercise

DOI:  https://doi.org/10.3390/molecules27227705
J Funct Biomater. 2022 Nov 05. pii: 221. [Epub ahead of print]13(4):

AMPK/mTOR Pathway Is Involved in Autophagy Induced by Magnesium-Incorporated TiO2 Surface to Promote BMSC Osteogenic Differentiation.

Guifang Wang, Jiaxin Luo, Yuqin Qiao, Dongdong Zhang, Yulan Liu, Wenjie Zhang, Xuanyong Liu, Xinquan Jiang.

  Magnesium has been extensively utilized to modify titanium implant surfaces based on its important function in promoting osteogenic differentiation. Autophagy has been proven to play a vital role in bone metabolism. Whether there is an association between autophagy and magnesium in promoting osteogenic differentiation remains unclear. In the present study, we focused on investigating the role of magnesium ions in early osteogenic activity and the underlying mechanism related to autophagy. Different concentrations of magnesium were embedded in micro-structured titanium surface layers using the micro-arc oxidation (MAO) technique. The incorporation of magnesium benefited cell adhesion, spreading, and viability; attenuated intracellular ATP concentrations and p-mTOR levels; and upregulated p-AMPK levels. This indicates the vital role of the ATP-related AMPK/mTOR signaling pathway in the autophagy process associated with osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) induced by magnesium modification on titanium surfaces. The enhanced osteogenic differentiation and improved cellular autophagy activity of BMSCs in their extraction medium further confirmed the function of magnesium ions. The results of the present study advance our understanding of the mechanism by which magnesium regulates BMSC osteogenic differentiation through autophagy regulation. Moreover, endowing implants with the ability to activate autophagy may be a promising strategy for enhancing osseointegration in the translational medicine field in the future.

Keywords:  autophagy; magnesium; osteogenic activity; surface modification; titanium

DOI:  https://doi.org/10.3390/jfb13040221