bims-amsmem 2022-08-21 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2022–08–21
seventeen papers selected by
Dipsikha Biswas, Københavns Universitet

Phosphatidic acid inhibits inositol synthesis by inducing nuclear translocation of kinase IP6K1 and repression of myo-inositol-3-P synthase.
Body composition and serum levels of matrix metalloproteinase-9, adiponectin and AMP-activated protein kinase in breast cancer survivors.
L-Arginine increases AMPK phosphorylation and the oxidation of energy substrates in hepatocytes, skeletal muscle cells, and adipocytes.
Chrysin improves diabetic nephropathy by regulating the AMPK-mediated lipid metabolism in HFD/STZ-induced DN mice.
PLK1 promotes cholesterol efflux and alleviates atherosclerosis by up-regulating ABCA1 and ABCG1 expression via the AMPK/PPARγ/LXRα pathway.
Gingko biloba-inspired lactone prevents osteoarthritis by activating the AMPK-SIRT1 signaling pathway.
Therapeutic Effects of Salvianolic Acid B on Angiotensin II-Induced Atrial Fibrosis by Regulating Atrium Metabolism via Targeting AMPK/FoxO1/miR-148a-3p Axis.
Aspirin blocks AMPK/SIRT3-mediated glycolysis to inhibit NSCLC cell proliferation.
Dietary L-arginine supplementation increases the hepatic expression of AMP-activated protein kinase in rats.
Energy crisis links to autophagy and ferroptosis in Alzheimer's disease: current evidence and future avenues.
Structure activity relationships leading to the identification of the indirect activator of AMPK, R419.
KCNK3 inhibits proliferation and glucose metabolism of lung adenocarcinoma via activation of AMPK-TXNIP pathway.
AMPK-related protein kinase ARK5 regulates subcellular localization of RNA-binding protein hnRNP A1 during hypertonic stress.
Treadmill Exercise Decreases Inflammation Via Modulating IL-6 Expression in the Rat Model of Middle Cerebral Artery Occlusion.
TBK1-mTOR Signaling Attenuates Obesity-Linked Hyperglycemia and Insulin Resistance.
Palmatine attenuates hepatocyte injury by promoting autophagy via the AMPK/mTOR pathway after alcoholic liver disease.
Endosome maturation links PI3Kα signaling to lysosome repopulation during basal autophagy.

J Biol Chem. 2022 Aug 10. pii: S0021-9258(22)00806-7. [Epub ahead of print] 102363

Phosphatidic acid inhibits inositol synthesis by inducing nuclear translocation of kinase IP6K1 and repression of myo-inositol-3-P synthase.

Pablo Lazcano, Michael W Schmidtke, Chisom Onu, Miriam L Greenberg.

  Inositol is an essential metabolite that serves as a precursor for structural and signaling molecules. Although perturbation of inositol homeostasis has been implicated in numerous human disorders, surprisingly little is known about how inositol levels are regulated in mammalian cells. A recent study in mouse embryonic fibroblasts (MEFs) demonstrated that nuclear translocation of inositol hexakisphosphate kinase 1 (IP6K1) mediates repression of myo-inositol-3-P synthase (MIPS), the rate-limiting inositol biosynthetic enzyme. Binding of IP6K1 to phosphatidic acid (PA) is required for this repression. Here, we elucidate the role of PA in IP6K1 repression. Our results indicate that increasing PA levels through pharmacological stimulation of phospholipase D (PLD) or direct supplementation of 18:1 PA induces nuclear translocation of IP6K1 and represses expression of the MIPS protein. We found that this effect was specific to PA synthesized in the plasma membrane, as ER-derived PA did not induce IP6K1 translocation. Furthermore, we determined that PLD-mediated PA synthesis can be stimulated by the master metabolic regulator 5' AMP-activated protein kinase (AMPK). We show that activation of AMPK by glucose deprivation or by treatment with the mood-stabilizing drugs valproate (VPA) or lithium recapitulated IP6K1 nuclear translocation and decreased MIPS expression. This study demonstrates for the first time that modulation of PA levels through the AMPK-PLD pathway regulates IP6K1-mediated repression of MIPS.

Keywords:  AMPK; Glucose; IP6K1; Inositol; Inositol phosphate; Lithium; MIPS; Phosphatidic acid; Phospholipase D; Valproate

DOI:  https://doi.org/10.1016/j.jbc.2022.102363
J Res Med Sci. 2022 ;27 48

Body composition and serum levels of matrix metalloproteinase-9, adiponectin and AMP-activated protein kinase in breast cancer survivors.

Zeinab Babaei, Hadi Parsian, Bahare Korani, Amrollah Mostafazadeh, Dariush Moslemi.

   Background: Available data suggest that obesity is related to changes in the several adipocyte-derived proteins levels, which are involved in cancer recurrence. The purpose of this work was to investigate the correlation between obesity with metalloproteinase-9 (MMP-9), adiponectin and adiponectin and AMP-activated protein kinase (AMPK) levels by comparing serum levels of MMP-9, AMPK in normal weight and obese breast cancer survivors.
Materials and Methods: In this cross-sectional study, 30 normal weight breast cancer survivors (body mass index [BMI] 18.5-25 kg/m2) and 30 obese breast cancer survivors (BMI ≥30 kg/m2) were investigated. Anthropometric parameters and serum levels of MMP-9, adiponectin, and AMPK were compared between the two groups.
Results: No differences were detected in the serum levels of MMP-9, adiponectin, and AMPK in obese patients and normal weight patients (P > 0.05). There were no correlations between MMP-9, adiponectin, and AMPK levels with anthropometric measurements in two groups (P > 0.05).
Conclusion: We found that there was a lack of correlation between obesity measures and serum levels of MMP-9, adiponectin, and AMPK. In breast cancer survivors, it seems that circulating levels of adiponectin, AMPK, and MMP-9 do not change in obesity state.

Keywords:  AMP-activated protein kinase; Adiponectin; breast cancer; matrix metalloproteinase-9; obesity

DOI:  https://doi.org/10.4103/jrms.JRMS_453_20
Amino Acids. 2022 Aug 16.

L-Arginine increases AMPK phosphorylation and the oxidation of energy substrates in hepatocytes, skeletal muscle cells, and adipocytes.

Wenjuan S Jobgen, Guoyao Wu.

  Previous work has shown that dietary L-arginine (Arg) supplementation reduced white fat mass in obese rats. The present study was conducted with cell models to define direct effects of Arg on energy-substrate oxidation in hepatocytes, skeletal muscle cells, and adipocytes. BNL CL.2 mouse hepatocytes, C2C12 mouse myotubes, and 3T3-L1 mouse adipocytes were treated with different extracellular concentrations of Arg (0, 15, 50, 100 and 400 µM) or 400 µM Arg + 0.5 mM NG-nitro-L-arginine methyl ester (L-NAME; an NOS inhibitor) for 48 h. Increasing Arg concentrations in culture medium dose-dependently enhanced (P < 0.05) the oxidation of glucose and oleic acid to CO2 in all three cell types, lactate release from C2C12 cells, and the incorporation of oleic acid into esterified lipids in BNL CL.2 and 3T3-L1 cells. Arg at 400 µM also stimulated (P < 0.05) the phosphorylation of AMP-activated protein kinase (AMPK) in all three cell types and increased (P < 0.05) NO production in C2C12 and BNL CL.2 cells. The inhibition of NOS by L-NAME moderately reduced (P < 0.05) glucose and oleic acid oxidation, lactate release, and the phosphorylation of AMPK and acetyl-CoA carboxylase (ACC) in BNL CL.2 cells, but had no effect (P > 0.05) on these variables in C2C12 or 3T3-L1 cells. Collectively, these results indicate that Arg increased AMPK activity and energy-substrate oxidation in BNL CL.2, C2C12, and 3T3-L1 cells through both NO-dependent and NO-independent mechanisms.

Keywords:  Arginine; Metabolism; Muscle cells; Nitric oxide; Substrate oxidation; White adipocytes

DOI:  https://doi.org/10.1007/s00726-022-03195-9
J Food Biochem. 2022 Aug 17. e14379

Chrysin improves diabetic nephropathy by regulating the AMPK-mediated lipid metabolism in HFD/STZ-induced DN mice.

Yingjun Zhou, Heng Tao, Nuo Xu, Shichun Zhou, Yuke Peng, Jianxiang Zhu, Shaowei Liu, Yaning Chang.

  Diabetic nephropathy (DN) is a highly prevalent and severe diabetic complication. It is urgent to explore high efficiency and minor side effects therapy for DN. Chrysin is a natural flavonoid with various biological activities found in honey and propolis, and has considerable potential to improve DN. The study was designed to explore the effects and the specific underlying mechanism of chrysin for DN in high-fat-diet (HFD) and streptozotocin (STZ) induced DN mice. Firstly, the study revealed that chrysin effectively improved obesity, insulin resistance (IR), renal function, and pathological injury in DN mice. Secondly, the study found that chrysin improved the key indices and markers of lipid accumulation, oxidative stress, and inflammation which are closely related to the development or progression of DN. Moreover, chrysin markedly modulated lipid metabolism by regulating Adenosine 5' monophosphate-activated protein kinase (AMPK) and essential downstream proteins. Furthermore, AMPK inhibitor (Dorsomorphin) intervention partially suppressed the positive effects of chrysin on all testing indicators, indicating that activated AMPK is crucial for chrysin action on DN. The present study demonstrated that chrysin may improve DN by regulating lipid metabolism, and activated AMPK plays a critical role in the regulation of chrysin. PRACTICAL APPLICATIONS: The study verified the positive effects of chrysin on obesity, insulin resistance, kidney injury, renal function, lipid accumulation, inflammation, and oxidative stress, which are closely related to the development or progression of diabetic nephropathy (DN). Moreover, we explored that chrysin improves DN by regulating AMPK-mediated lipid metabolism. Furthermore, the AMPK inhibitor was used to confirm that activated AMPK plays a critical role in the effects of chrysin. These results could offer a full explanation and a potential option for adjuvant therapy of DN diabetes with chrysin.

Keywords:  AMPK; chrysin; diabetic nephropathy; lipid metabolism

DOI:  https://doi.org/10.1111/jfbc.14379
Biochim Biophys Acta Mol Cell Biol Lipids. 2022 Aug 15. pii: S1388-1981(22)00111-1. [Epub ahead of print] 159221

PLK1 promotes cholesterol efflux and alleviates atherosclerosis by up-regulating ABCA1 and ABCG1 expression via the AMPK/PPARγ/LXRα pathway.

Heng-Jing Hu, Xiu-Heng Wang, Tian-Qing Zhang, Yao Liu, Zheng-Rong Chen, Zhi-Zhu Zhang, Hong Huang, Hui-Fang Tang, Zhi-Sheng Jiang.

  Polo-like kinase 1 (PLK1) is a serine/threonine kinase involving lipid metabolism and cardiovascular disease. However, its role in atherogenesis has yet to be determined. The aim of this study was to observe the impact of PLK1 on macrophage lipid accumulation and atherosclerosis development and to explore the underlying mechanisms. We found a significant reduction of PLK1 expression in lipid-loaded macrophages and atherosclerosis model mice. Lentivirus-mediated overexpression of PLK1 promoted cholesterol efflux and inhibited lipid accumulation in THP-1 macrophage-derived foam cells. Mechanistic analysis revealed that PLK1 stimulated the phosphorylation of AMP-activated protein kinase (AMPK), leading to activation of the peroxisome proliferator-activated receptor γ (PPARγ)/liver X receptor α (LXRα) pathway and up-regulation of ATP binding cassette transporter A1 (ABCA1) and ABCG1 expression. Injection of lentiviral vector expressing PLK1 increased reverse cholesterol transport, improved plasma lipid profiles and decreased atherosclerotic lesion area in apoE-deficient mice fed a Western diet. PLK1 overexpression also facilitated AMPK and HSL phosphorylation and enhanced the expression of PPARγ, LXRα, ABCA1, ABCG1 and LPL in the aorta. In summary, these data suggest that PLK1 inhibits macrophage lipid accumulation and mitigates atherosclerosis by promoting ABCA1- and ABCG1-dependent cholesterol efflux via the AMPK/PPARγ/LXRα pathway.

Keywords:  AMP-activated protein kinase (AMPK); Atherosclerosis; Lipid accumulation; Liver X receptor α (LXRα); Peroxisome proliferator-activated receptor γ (PPARγ); Polo-like kinase 1 (PLK1)

DOI:  https://doi.org/10.1016/j.bbalip.2022.159221
Arthritis Res Ther. 2022 Aug 18. 24(1): 197

Gingko biloba-inspired lactone prevents osteoarthritis by activating the AMPK-SIRT1 signaling pathway.

Zhijian Zhao, Yang Liu, Yingjie Lu, Mingzhuang Hou, Xu Shen, Huilin Yang, Qin Shi, Yijian Zhang, Fan He, Xuesong Zhu.

   BACKGROUND: Uncoupled extracellular matrix (ECM) causes cartilage degeneration and osteoarthritis (OA) by suppressing the synthesis and activating the degradation of ECM components. Gingko biloba is a natural Chinese herb with a variety of biological functions; however, the extent to which it can protect against OA and the mechanisms involved are unknown.
METHODS: In our study, using bioinformatics tools, we were able to identify an important lactone, bilobalide (BB), from Gingko biloba. In vitro experiments were performed to evaluate the potential therapeutic effects of BB on ECM homeostasis. In vivo experiments were conducted to assess the protection of systemic administration of BB on cartilage degeneration. Molecular mechanisms underlying BB-regulated anti-arthritic role were further explored.
RESULTS: In interleukin-1β-incubated human chondrocytes, in vitro treatment with BB increased the expression of cartilage anabolic proteins, while inhibiting the activities of ECM degrading enzymes. In a mice model, systemic administration of BB, in vivo, prevented post-traumatic cartilage erosion and attenuated the formation of abnormal osteophytes in the subchondral bone. Mechanistically, the activation of the adenosine 5'-monophosphate-activated protein kinase (AMPK)-sirtuin 1 (SIRT1) signaling pathway was involved in the anti-arthritic effects of BB. In vitro, blocking BB's chondroprotection with the AMPK-specific inhibitor Compound C abrogated it.
CONCLUSIONS: These results demonstrated that BB extracted from Gingko biloba regulates ECM balance to prevent OA by activating the AMPK-SIRT1 signaling pathway. This study proposed the monomer BB, a traditional Chinese medicine, as a de novo therapeutic insight for OA. Schematic representation of the experimental design. Based on the bioinformatic analysis, bilobalide (BB), a natural herb Gingko biloba-derived ingredient, was identified as a candidate for treating osteoarthritis. In vitro, BB treatment not only facilitates cartilage extracellular matrix synthesis but also inhibits proteolytic enzyme activities. In vivo intraperitoneal injection of BB improves cartilage degeneration and subchondral bone sclerosis. BB, in particular, had anti-arthritic effects by activating the AMPK-SIRT1 signaling pathway.

Keywords:  AMPK; Bilobalide; Extracellular matrix; Osteoarthritis; SIRT1

DOI:  https://doi.org/10.1186/s13075-022-02890-y
J Cardiovasc Transl Res. 2022 Aug 19.

Therapeutic Effects of Salvianolic Acid B on Angiotensin II-Induced Atrial Fibrosis by Regulating Atrium Metabolism via Targeting AMPK/FoxO1/miR-148a-3p Axis.

Jie Liu, Qijuan Sun, Xiaotong Sun, Qian Wang, Guangchen Zou, Dewei Wang, Baoxiang Zhuang, Zhaodong Juan, Rui Zhang, Daoliang Zhang.

  The present study highlights the effects of salvianolic acid B (Sal B) on angiotensin II (Ang II)-activated atrial fibroblasts as well as the associated potential mechanism from the metabonomics perspective. Metabolic profile analysis performed an optimal separation of the Ang II and control group, indicating a recovery impact of Sal B on Ang II-activated fibroblasts (FBs). We found that metabolite levels in the Ang II + Sal B group were reversed to normal. Moreover, 23 significant metabolites were identified. Metabolic network analysis indicated that these metabolites participated in purine metabolism and FoxO signaling pathway. We found that Sal B activated AMP-activated protein kinase (AMPK) phosphorylation, which further promoted FoxO1 activation and increased miR-148a-3p level. We further verified that Sal B modulate the abnormal AMP, phosphocreatine, glutathione (GSH), and reactive oxygen species (ROS) production in Ang II-stimulated FBs. Collectively, Sal B can protect the Ang II-activated FBs from fibrosis and oxidative stress via AMPK/FoxO1/miRNA-148a-3p axis.

Keywords:  AMPK; Atrial fibrosis; FoxO1; Metabonomics; Salvianolic acid B

DOI:  https://doi.org/10.1007/s12265-022-10303-3
Eur J Pharmacol. 2022 Aug 15. pii: S0014-2999(22)00469-1. [Epub ahead of print] 175208

Aspirin blocks AMPK/SIRT3-mediated glycolysis to inhibit NSCLC cell proliferation.

Guanghui Ren, Yan Ma, Xingjie Wang, Zhaodi Zheng, Guorong Li.

  Non-small cell lung cancer (NSCLC) has the highest incidence and mortality in the world. Aspirin has been reported to promote apoptosis, inhibit proliferation, stemness, angiogenesis, cancer-associated inflammation and migration in NSCLC. But the effect of aspirin on aerobic glycolysis in NSCLC is less reported. In the present study, we investigated whether aspirin blocked aerobic glycolysis of NSCLC cell to inhibit proliferation. Our results showed that aspirin inhibited viability, PCNA expression, ability of colony formation, and reduced level of two glycolysis products, pyruvic acid and lactic acid, accompanied with reduced mitochondrial membrane potential (MMP), PGC-1α expression and ROS production to induce mitochondrial dysfunction in NSCLC cells. AMPK and mitochondrial-localized deacetylase sirtuin3 (SIRT3) were identified as the relevant molecular targets in glycolysis, but function mechanism and relationship between AMPK and SIRT3 for aspirin induced glycolysis inhibition remain unknown in cancer cells. The investigation of underlying mechanisms here indicated that aspirin activated AMPK pathway in dose- and time-dependent manners to inhibit aerobic glycolysis and proliferation by upregulating SIRT3 after application of compound C (CC), an inhibitor of AMPK activity or SIRT3 siRNA. Upon activation of SIRT3, aspirin promoted the release of hexokinase-II (HK-II) from mitochondria outer membrane to cytosol by deacetylating cyclophilin D (CypD). Consistently, aspirin significantly inhibited the growth of NSCLC xenografts and exhibited antitumor activity probably through AMPK/SIRT3/HK-II pathway in vivo. Collectively, AMPK/SIRT3/HK-II pathway plays a critical role in anticancer effects of aspirin, and our findings might serve as potential target for clinical practice and chemoprevention of aspirin in NSCLC.

Keywords:  AMPK; Aerobic glycolysis; Aspirin; Non-small cell lung cancer; Proliferation; SIRT3

DOI:  https://doi.org/10.1016/j.ejphar.2022.175208
Amino Acids. 2022 Aug 16.

Dietary L-arginine supplementation increases the hepatic expression of AMP-activated protein kinase in rats.

Wenjuan S Jobgen, Guoyao Wu.

  The goal of this study was to elucidate the molecular mechanisms responsible for the anti-obesity effect of L-arginine supplementation in diet-induced obese rats. Male Sprague-Dawley rats were fed either a low-fat or high-fat diet for 15 weeks. Thereafter, lean or obese rats were pair-fed their same respective diets and received drinking water containing either 1.51% L-arginine-HCl or 2.55% L-alanine (isonitrogenous control) for 12 weeks. Gene and protein expression of key enzymes in the metabolism of energy substrates were determined using real-time polymerase-chain reaction and western blotting techniques. The mRNA levels of hepatic fatty acid synthase and stearoyl-CoA desaturase were reduced (P < 0.05) but those of hepatic AMP-activated protein kinase-α (AMPKα), peroxisome proliferator activator receptor γ coactivator-1α, and carnitine palmitoyltransferase I (CPT-I), as well as skeletal muscle CPT-I were increased (P < 0.05) by L-arginine treatment. The protein expression and activity of hepatic AMPKα markedly increased (P < 0.05) but the activity of hepatic acetyl-CoA carboxylase (ACC) decreased (P < 0.05) in response to dietary L-arginine supplementation. Collectively, our results indicate that liver is the major target for the action of dietary L-arginine supplementation on reducing white-fat mass in diet-induced obese rats by inhibiting fatty acid synthesis and increasing fatty acid oxidation via the AMPK-ACC signaling pathway. Additionally, increased CPT-I expression in skeletal muscle may also contribute to the enhanced oxidation of long-chain fatty acids in L-arginine-supplemented rats.

Keywords:  Arginine; Liver; Metabolism; Nutrition; Obesity; Rats

DOI:  https://doi.org/10.1007/s00726-022-03194-w
Curr Neuropharmacol. 2022 Aug 17.

Energy crisis links to autophagy and ferroptosis in Alzheimer's disease: current evidence and future avenues.

Da-Long He, Yong-Gang Fan, Zhan-You Wang.

  Alzheimer's disease (AD) is one of the most common neurodegenerative diseases worldwide. The occult nature of the onset and the uncertainty of the etiology largely impede the development of therapeutic strategies for AD. Previous studies revealed that the disorder of energy metabolism in the brains of AD patients appears far earlier than the typical pathological features of AD, suggesting a tight association between energy crisis and the onset of AD. Energy crisis in the brain is known to be induced by the reductions in glucose uptake and utilization, which may be ascribed to the diminished expressions of cerebral glucose transporters (GLUTs), insulin resistance, mitochondrial dysfunctions, and lactate dysmetabolism. Notably, the energy sensors such as peroxisome proliferators-activated receptor (PPAR), transcription factor EB (TFEB), AMP-activated protein kinase (AMPK) were shown to be the critical regulators of autophagy, and autophagy plays important roles in regulating beta-amyloid (Aβ) metabolism, tau phosphorylation, neuroinflammation, iron dynamics, as well as ferroptosis. In this study, we summarized the current knowledge on the molecular mechanisms involved in the energy dysmetabolism of AD, and discussed the interplays existing between energy crisis, autophagy and ferroptosis. In addition, we highlighted the potential network that autophagy may serve as a bridge between energy crisis and ferroptosis in the progression of AD. A deeper understanding of the relationship between energy dysmetabolism and AD may provide new strategies for treating AD, meanwhile, the energy crisis in the progression of AD should gain more attention.

Keywords:  Alzheimer's disease; autophagy; beta-amyloid; energy crisis; ferroptosis; iron metabolism; tau protein

DOI:  https://doi.org/10.2174/1570159X20666220817140737
Bioorg Med Chem. 2022 Aug 01. pii: S0968-0896(22)00344-3. [Epub ahead of print]71 116951

Structure activity relationships leading to the identification of the indirect activator of AMPK, R419.

Simon J Shaw, Dane A Goff, David C Carroll, Rajinder Singh, David J Sweeny, Gary Park, Yonchu Jenkins, Vadim Markovtsov, Tian-Qiang Sun, Sarkiz D Issakani, Yasumichi Hitoshi, Donald G Payan.

  Using an in-cell AMPK activation assay, we have developed structure-activity relationships around a hit pyridine dicarboxamide 5 that resulted in 40 (R419). A particular focus was to retain the on-target potency while also improving microsomal stability and reducing off-target activities, including hERG inhibition. We were able to show that removing a tertiary amino group from the piperazine unit of hit compound 5 improved microsomal stability while hERG inhibition was improved by modifying the substitution of the central core pyridine ring. The SAR resulted in 40, which continues to maintain on-target potency. Compound 40 was able to activate AMPK in vivo after oral administration and showed efficacy in animal models investigating activation of AMPK as a therapy for glucose control (both db/db and DIO mouse models).

Keywords:  AMPK; Diabetes; Mitochondria; R419; Structure activity relationships; hERG

DOI:  https://doi.org/10.1016/j.bmc.2022.116951
Cell Death Discov. 2022 Aug 13. 8(1): 360

KCNK3 inhibits proliferation and glucose metabolism of lung adenocarcinoma via activation of AMPK-TXNIP pathway.

Guofu Lin, Lanlan Lin, Hai Lin, Wenhan Chen, Luyang Chen, Xiaohui Chen, Shaohua Chen, Qinhui Lin, Yuan Xu, Yiming Zeng.

Non-small cell lung cancer (NSCLC) is a primary histological subtype of lung cancer with increased morbidity and mortality. K+ channels have been revealed to be involved in carcinogenesis in various malignant tumors. However, TWIK-related acid-sensitive potassium channel 1 (TASK-1, also called KCNK3), a genetic member of K2P channels, remains an enigma in lung adenocarcinoma (LUAD). Herein, we investigated the pathological process of KCNK3 in proliferation and glucose metabolism of LUAD. The expressions of KCNK3 in LUAD tissues and corresponding adjacent tissues were identified by RNA sequencing, quantitative real-time polymerase chain reaction, western blot, and immunohistochemistry. Gain and loss-of-function assays were performed to estimate the role of KCNK3 in proliferation and glucose metabolism of LUAD. Additionally, energy metabolites of LUAD cells were identified by targeted metabolomics analysis. The expressions of metabolic molecules and active biomarkers associated with AMPK-TXNIP signaling pathway were detected via western blot and immunofluorescence. KCNK3 was significantly downregulated in LUAD tissues and correlated with patients' poor prognosis. Overexpression of KCNK3 largely regulated the process of oncogenesis and glycometabolism in LUAD in vitro and in vivo. Mechanistic studies found that KCNK3-mediated differential metabolites were mainly enriched in AMPK signaling pathway. Furthermore, rescue experiments demonstrated that KCNK3 suppressed proliferation and glucose metabolism via activation of the AMPK-TXNIP pathway in LUAD cells. In summary, our research highlighted an emerging role of KCNK3 in the proliferative activity and glycometabolism of LUAD, suggesting that KCNK3 may be an optimal predictor for prognosis and a potential therapeutic target of LUAD.

DOI: https://doi.org/10.1038/s41420-022-01152-9
J Biol Chem. 2022 Aug 10. pii: S0021-9258(22)00807-9. [Epub ahead of print] 102364

AMPK-related protein kinase ARK5 regulates subcellular localization of RNA-binding protein hnRNP A1 during hypertonic stress.

Krishna Bhattarai, Travis Richard, Thet Fatica, Brianna Frangione, William G Willmore, Martin Holcik.

  The heterogeneous nuclear ribonucleoprotein hnRNP A1 is a nucleocytoplasmic-shuttling RNA-binding protein that plays an important role in nucleic acid metabolism and gene expression regulation. The function of hnRNP A1 is determined in part by its specific location within the cell. Although some work has been done to elucidate the signaling pathways that regulate the cellular localization of hnRNP A1, the precise mechanism(s), including physiological and pathophysiological conditions that alter hnRNP A1 localization, are not known. We previously conducted an unbiased RNAi-based kinome-wide screen to identify kinases that regulate hnRNP A1 localization during hypertonic stress. One of the hits from this screen is AMPK-related protein kinase 5 (ARK5). Here, we validate ARK5 as the kinase responsible for controlling hnRNP A1 subcellular localization in response to hypertonic stress. We find using immunoprecipitation and in vitro kinase assay methods that ARK5 directly interacts with and phosphorylates hnRNP A1 on serine residues within the F-peptide region. We further show that the M9 motif of hnRNP A1 is essential for the ARK5-hnRNP A1 interaction and subsequent phosphorylation. In addition, the silencing of ARK5 increases the expression of anti-apoptotic protein Bcl-xL and consequently delays caspase activation during hypertonic stress. Our results indicate that ARK5 phosphorylates hnRNP A1 and regulates its subcellular localization during hypertonic stress.

Keywords:  AMPK-related protein kinase 5 (ARK5); Bcl‐xL; Caspase; Co-Immunoprecipitation; Hypertonic stress; heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1); phosphorylation

DOI:  https://doi.org/10.1016/j.jbc.2022.102364
Neurocrit Care. 2022 Aug 18.

Treadmill Exercise Decreases Inflammation Via Modulating IL-6 Expression in the Rat Model of Middle Cerebral Artery Occlusion.

Hui Feng, Yinliang Qi, Xinlong Wang, Fangyu Chen, Xueping Li.

   BACKGROUND: Long-term bed rest in neurointensive care (NIC) patients leads to skeletal muscle atrophy and cognitive dysfunction, which seriously affects the physical fitness and final prognosis of critically ill patients. Exercise therapy plays an increasingly important role in the treatment and rehabilitation of patients with sarcopenia. However, the therapeutic effect and mechanism of exercise therapy for patients with neurological impairment remain unclear.
METHODS: Serum samples of NIC patients before and after exercise therapy and normal people were collected to detect interleukin-6 (IL-6) and interleukin-1β levels by enzyme-linked immunosorbent assay (ELISA). Middle cerebral artery occlusion (MCAO) was used for the construction of a rat model. The Morris water maze test, exploration test, and open-field test were used to assess neurological function in rats. Western blot and quantitative real-time polymerase chain reaction were performed to evaluate the activation of IL-6/adenosine-monophosphate-activated protein kinase (AMPK) signaling.
RESULTS: Exercise therapy attenuated IL-6 expression in NIC patients. Exercise therapy alleviated cognitive dysfunctions and decreased IL-6 expression in MCAO rats. Exercise therapy alleviated gastrocnemius muscle injury in rats after MCAO by modulating IL-6/AMPK signaling.
CONCLUSIONS: Treadmill exercise decreases inflammation in MCAO rats via modulating IL-6/AMPK signaling.

Keywords:  AMPK; FOXO3; IL-6; Neurointensive care

DOI:  https://doi.org/10.1007/s12028-022-01575-3
Diabetes. 2022 Aug 19. pii: db220256. [Epub ahead of print]

TBK1-mTOR Signaling Attenuates Obesity-Linked Hyperglycemia and Insulin Resistance.

Cagri Bodur, Dubek Kazyken, Kezhen Huang, Aaron Seth Tooley, Kae Won Cho, Tammy M Barnes, Carey N Lumeng, Martin G Myers, Diane C Fingar.

The innate immune kinase TBK1 (TANK-binding kinase 1) responds to microbial-derived signals to initiate responses against viral and bacterial pathogens. More recent work implicates TBK1 in metabolism and tumorigenesis. The kinase mTOR (mechanistic target of rapamycin) integrates diverse environmental cues to control fundamental cellular processes. Our prior work demonstrated in cells that TBK1 phosphorylates mTOR (on S2159) to increase mTORC1 and mTORC2 catalytic activity and signaling. Here we investigate a role for TBK1-mTOR signaling in control of glucose metabolism in vivo. We find that diet induced obese (DIO) but not lean mice bearing a whole-body "TBK1 resistant" Mtor S2159A knockin allele (MtorA/A) display exacerbated hyperglycemia and systemic insulin resistance with no change in energy balance. Mechanistically, Mtor S2159A knockin in DIO mice reduces mTORC1 and mTORC2 signaling in response to insulin and innate immune agonists, reduces anti-inflammatory gene expression in adipose tissue, and blunts anti-inflammatory macrophage M2 polarization, phenotypes shared by mice with tissue-specific inactivation of TBK1 or mTOR complexes. Tissues from DIO mice display elevated TBK1 activity and mTOR S2159 phosphorylation relative to lean mice. We propose a model whereby obesity-associated signals increase TBK1 activity and mTOR phosphorylation, which boosts mTORC1 and mTORC2 signaling in parallel to the insulin pathway, thereby attenuating insulin resistance to improve glycemic control during diet-induced obesity.

DOI: https://doi.org/10.2337/db22-0256
Drug Dev Res. 2022 Aug 17.

Palmatine attenuates hepatocyte injury by promoting autophagy via the AMPK/mTOR pathway after alcoholic liver disease.

Guo-Shuai Lin, Mao-Mao Zhao, Qi-Chao Fu, Shu-Yi Zhao, Tao-Tao Ba, Hong-Xia Yu.

  Alcoholic liver disease is one of the diseases with the highest fatality rate worldwide. The cellular process of autophagy which recycles damaged organelles to maintain protein and organelle homeostasis is found to positively influence survival during hepatic insufficiency, although the mechanism is poorly understood. Palmatine (PLT) has a variety of biological functions, such as broad-spectrum antibacterial action, neuroprotective, antioxidant stress, and antiviral and anti-inflammatory activities. However, it is not known whether PLT has a protective effect against alcoholic liver injury. Here, we investigated the protective effect of PLT in a cellular model of alcohol-induced acute liver injury and further explored its mechanism of action. In this study, we show for the first time that PLT attenuates alcohol-induced hepatocyte injury by promoting autophagy to play an essential protective role. As PLT treatment induced a brief increase in LC3-II conversion and p62 degradation, it also upregulated the expression of ATG5 and ATG7. The expression levels of the proapoptotic proteins Bax, Caspase 3, and Caspase 9 significantly decreased, while the antiapoptotic protein levels of Bcl-2 upregulated after treatment with PLT. However, in presence of the autophagy inhibitor, 3-methyladenine, the effect of PLT in inhibiting ethanol-induced hepatocyte injury reversed significantly. Mechanistically, the protective effects of PLT may be mediated by promoting the activation of the AMP-activated protein kinase/mammalian target of rapamycin signaling pathway. Therefore, we believe that the development of alcoholic liver injuries may be controlled by PLT by inhibiting hepatocyte apoptosis through the autophagy pathway. The study lays a solid theoretical and practical basis for future animal models and clinical studies of PLT.

Keywords:  AMPK/mTOR; alcoholic liver diseases; apoptosis; autophagy; palmatine

DOI:  https://doi.org/10.1002/ddr.21981
EMBO J. 2022 Aug 15. e110398

Endosome maturation links PI3Kα signaling to lysosome repopulation during basal autophagy.

Samuel J Rodgers, Emily I Jones, Senthil Arumugam, Sabryn A Hamila, Jill Danne, Rajendra Gurung, Matthew J Eramo, Randini Nanayakkara, Georg Ramm, Meagan J McGrath, Christina A Mitchell.

  Autophagy depends on the repopulation of lysosomes to degrade intracellular components and recycle nutrients. How cells co-ordinate lysosome repopulation during basal autophagy, which occurs constitutively under nutrient-rich conditions, is unknown. Here, we identify an endosome-dependent phosphoinositide pathway that links PI3Kα signaling to lysosome repopulation during basal autophagy. We show that PI3Kα-derived PI(3)P generated by INPP4B on late endosomes was required for basal but not starvation-induced autophagic degradation. PI(3)P signals were maintained as late endosomes matured into endolysosomes, and served as the substrate for the 5-kinase, PIKfyve, to generate PI(3,5)P2 . The SNX-BAR protein, SNX2, was recruited to endolysosomes by PI(3,5)P2 and promoted lysosome reformation. Inhibition of INPP4B/PIKfyve-dependent lysosome reformation reduced autophagic clearance of protein aggregates during proteotoxic stress leading to increased cytotoxicity. Therefore under nutrient-rich conditions, PI3Kα, INPP4B, and PIKfyve sequentially contribute to basal autophagic degradation and protection from proteotoxic stress via PI(3,5)P2 -dependent lysosome reformation from endolysosomes. These findings reveal that endosome maturation couples PI3Kα signaling to lysosome reformation during basal autophagy.

Keywords:  INPP4B; PI3Kα; PIKfyve; autophagy; lysosome

DOI:  https://doi.org/10.15252/embj.2021110398