bims-amsmem 2023-02-12 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2023–02–12
eightteen papers selected by
Dipsikha Biswas, Københavns Universitet

L-Fucose Suppresses Lipid Accumulation via the AMPK Pathway in 3T3-L1 Adipocytes.
Elevated fatty acid β-oxidation by leptin contributes to the proinflammatory characteristics of fibroblast-like synoviocytes from RA patients via LKB1-AMPK pathway.
Ginkgo biloba extract protects against diabetic cardiomyopathy by restoring autophagy via adenosine monophosphate-activated protein kinase/mammalian target of the rapamycin pathway modulation.
RRP Regulates Autophagy through the AMPK Pathway to Alleviate the Effect of Cell Senescence on Atherosclerosis.
Thalidomide Attenuates Mast Cell Activation by Upregulating SHP-1 Signaling and Interfering with the Action of CRBN.
Baicalin ameliorates high fat diet-induced nonalcoholic fatty liver disease in mice via adenosine monophosphate-activated protein kinase-mediated regulation of SREBP1/Nrf2/NF-κB signaling pathways.
Snf1/AMPK fine-tunes TORC1 signaling in response to glucose starvation.
Metformin regulates myoblast differentiation through an AMPK-dependent mechanism.
Imidazo[1,2-a]pyridine Derivatives as AMPK Activators: Synthesis, Structure-Activity Relationships, and Regulation of Reactive Oxygen Species in Renal Fibroblasts.
Effect and mechanisms of dexmedetomidine combined with macrophage migration inhibitory factor inhibition on the expression of inflammatory factors and AMPK in mice.
Kazinol B protects H9c2 cardiomyocytes from hypoxia/reoxygenation-induced cardiac injury by modulating the AKT/AMPK/Nrf2 signalling pathway.
Deficiency of S100A9 Alleviates Sepsis-Induced Acute Liver Injury through Regulating AKT-AMPK-Dependent Mitochondrial Energy Metabolism.
Caloric restriction increases the resistance of aged heart to myocardial ischemia/reperfusion injury via modulating AMPK-SIRT1-PGC1a energy metabolism pathway.
Mutation of regulatory phosphorylation sites in PFKFB2 does not affect the anti-fibrotic effect of metformin in the kidney.
Naringin protects mice from D-galactose-induced lung aging and mitochondrial dysfunction: Implication of SIRT1 pathways.
Effects of diazoxide on streptozotocin induced β cell damage via HSP70/HSP90/TLR4/AMPK signaling pathways.
Vam6 reduces iNKT cell function in tumor via modulating AMPK/mTOR pathways.
Metformin alleviates ethanol-induced cardiomyocyte injury by activating AKT/Nrf2 signaling in an ErbB2-dependent manner.

Nutrients. 2023 Jan 18. pii: 503. [Epub ahead of print]15(3):

L-Fucose Suppresses Lipid Accumulation via the AMPK Pathway in 3T3-L1 Adipocytes.

Tomohiko Nakao, Shiro Otaki, Yuri Kominami, Soichi Watanabe, Miho Ito, Teruki Aizawa, Yusuke Akahori, Hideki Ushio.

  L-fucose (Fuc), a monosaccharide with different biological functions in various organisms, exhibits potent anti-obesity effects in obese mice. However, the mechanisms underlying its anti-obesity effects remain largely unknown. In this study, we aimed to investigate the effects of Fuc on lipid metabolism and insulin signaling in 3T3-L1 adipocytes. We found that Fuc treatment suppressed lipid accumulation during adipocyte differentiation. Additionally, Fuc treatment enhanced the phosphorylation of AMP-activated kinase (AMPK) and its downstream pathways, responsible for the regulation of fatty acid oxidation and lipolysis. Furthermore, Fuc-induced activation of the AMPK pathway was diminished by the AMPK inhibitor Compound C, and Fuc treatment considerably promoted glucose uptake via Akt activation in an insulin-resistant state. These findings provide a basis for elucidating the mechanism underlying the anti-obesity effect of Fuc, which may, in the future, be considered as a therapeutic compound for treating obesity and related diseases.

Keywords:  AMPK; L-fucose; anti-obesity; insulin signaling; lipolysis

DOI:  https://doi.org/10.3390/nu15030503
Cell Death Dis. 2023 Feb 09. 14(2): 97

Elevated fatty acid β-oxidation by leptin contributes to the proinflammatory characteristics of fibroblast-like synoviocytes from RA patients via LKB1-AMPK pathway.

Jing Wei, Xinxin Huang, Xing Zhang, Guanghong Chen, Cheng Zhang, Xinyang Zhou, Jingjing Qi, Yan Zhang, Xia Li.

Fibroblast-like synoviocytes (FLS) maintain chronic inflammation leading to joint destruction in rheumatoid arthritis (RA). Fatty acid β-oxidation (FAO) regulates cell function. Here, we aimed to investigate the effect of FAO enhanced by leptin on the characteristics of RA-FLS and elucidate the potential metabolic mechanism. Key enzymes involved in lipid metabolism were detected with qPCR in HSF, MH7A cell line and isolated RA-FLS treated with RA or healthy control (HC) serum. In some experiments, FAO inhibitor, etomoxir (ETO) or anti-leptin antibody were added into serum-treated RA-FLS. In other experiments, RA-FLS were stimulated with leptin together with ETO or AMP-activated protein kinase (AMPK) inhibitor compound C (CC) or silencing liver kinase B1 (LKB1). Cell proliferation, proinflammatory factor production, pro-angiogenesis, chemoattractive potential, FAO-related key enzymes, AMPK and LKB1 in FLS were analyzed. FAO-related key enzymes were evaluated in serum-treated RA-FLS with or without anti-leptin antibody. Related functions of leptin-stimulated RA-FLS were examined in the presence or absence of ETO. AMP-activated protein kinase (AMPK) and liver kinase B1 (LKB1) in leptin-stimulated RA-FLS were tested with western blot. Activation of AMPK in leptin-stimulated RA-FLS was detected after silencing LKB1. We found that MH7A cell line and RA serum-treated FLS exhibited upregulated FAO, and ETO could inhibit the proinflammatory phenotypes of RA-FLS. The addition of anti-leptin antibody suppressed the elevation of FAO mediated by RA serum. More importantly, leptin promoted the proinflammatory characteristics of RA-FLS, which was reversed by ETO. Leptin activated AMPK by upregulating LKB1. CC impaired leptin-induced CPT-1A expression in RA-FLS. Our study uncovers that elevated FAO mediated by leptin drives abnormal function of RA-FLS and suggests leptin or FAO inhibition may serve as a promising therapeutic strategy for RA.

DOI: https://doi.org/10.1038/s41419-023-05641-2
Phytother Res. 2023 Feb 08.

Ginkgo biloba extract protects against diabetic cardiomyopathy by restoring autophagy via adenosine monophosphate-activated protein kinase/mammalian target of the rapamycin pathway modulation.

Xueyao Yang, Xin Zhao, Yanfei Liu, Yue Liu, Libo Liu, Ziyu An, Haoran Xing, Jinfan Tian, Xiantao Song.

  Studies demonstrated that Ginkgo biloba extract (GBE) played a cardioprotective role in diabetic conditions. Impaired autophagy is one of the mechanisms underlying diabetic cardiomyopathy (DCM). The effect of GBE on autophagy has been observed in several diseases; however, whether GBE can ameliorate DCM by regulating autophagy remains unclear. Here, we investigated the effect of GBE on DCM and the potential mechanisms regarding autophagy using a streptozotocin (STZ)-induced diabetic rat model and a high-glucose (HG)-stimulated H9C2 cell model. We demonstrated that GBE attenuated metabolic disturbances, improved cardiac function, and reduced myocardial pathological changes in diabetic rats. Impaired autophagy as well as dysregulation of the adenosine monophosphate-activated protein kinase/ mammalian target of the rapamycin (AMPK/mTOR) signaling pathway were observed in diabetic hearts, as evidenced by the reduced conversion of LC3B-I to LC3B-II along with excessive p62 accumulation, decreased AMPK phosphorylation, and increased mTOR phosphorylation, which could be reversed by GBE treatment. In vitro, GBE reduced the apoptosis induced by HG in H9C2 cells by activating AMPK and inhibiting mTOR to restore autophagy. However, this effect was inhibited by the AMPK inhibitor Compound C. In conclusion, the ameliorative effect of GBE on DCM might be dependent on the restoration of autophagy through modulation of the AMPK/mTOR pathway.

Keywords:  AMPK/mTOR; Ginkgo biloba extract; autophagy; diabetic cardiomyopathy

DOI:  https://doi.org/10.1002/ptr.7746
Oxid Med Cell Longev. 2023 ;2023 9645789

RRP Regulates Autophagy through the AMPK Pathway to Alleviate the Effect of Cell Senescence on Atherosclerosis.

Dekun Liu, Yueyue Song, Tinging Song, Lin Lin, Lei Zhang, Qiong Yang, Xingchen Niu, Dan Liang, Jiufeng Yin, Wenqing Yang, Dan Zhang.

Autophagy is closely associated with atherosclerosis and other cardiovascular diseases (CVD). Compound Danshen prescription is widely used as a clinical antiatherosclerotic drug. In our previous studies, we have shown that the combined active component, ginsenoside Rg1-notoginsenoside R1-protocatechualdehyde (RRP), can effectively alleviate endothelial dysfunction and reduce atherosclerotic plaques. However, the association between cellular senescence, caused by reduced autophagy, and atherosclerosis remains unclear. In this study, we investigated whether RRP can enhance autophagy and alleviate cell senescence through the AMPK pathway. Our results showed that RRP reduced the secretion of inflammatory factors in the serum of atherosclerotic mice, enhanced autophagy, and alleviated aortic aging in mice, thus reducing atherosclerotic plaques. In human aortic endothelial cells (HAECs), RRP effectively enhanced autophagy and inhibited senescence by activating the AMPK pathway. When AMPKα was silenced, the effect of RRP was inhibited, thus reversing its antiaging effect. Overall, our results show that RRP regulates autophagy through the AMPK pathway, thereby inhibiting cell senescence and alleviating the progression of atherosclerosis, suggesting that RRP may be a potential candidate drug for the treatment of atherosclerosis.

DOI: https://doi.org/10.1155/2023/9645789
Cells. 2023 Feb 01. pii: 469. [Epub ahead of print]12(3):

Thalidomide Attenuates Mast Cell Activation by Upregulating SHP-1 Signaling and Interfering with the Action of CRBN.

Hyeun-Wook Chang, Kyeong-Hwa Sim, Youn-Ju Lee.

  Allergy is a chronic inflammatory disease, and its incidence has increased worldwide in recent years. Thalidomide, which was initially used as an anti-emetic drug but was withdrawn due to its teratogenic effects, is now used to treat blood cancers. Although the anti-inflammatory and immunomodulatory properties of thalidomide have been reported, little is known about its influence on the mast cell-mediated allergic reaction. In the present study, we aimed to evaluate the anti-allergic activity of thalidomide and the underlying mechanism using mouse bone marrow-derived mast cells (BMMCs) and passive cutaneous anaphylaxis (PCA) mouse models. Thalidomide markedly decreased the degranulation and release of lipid mediators and cytokines in IgE/Ag-stimulated BMMCs, with concurrent inhibition of FcεRI-mediated positive signaling pathways including Syk and activation of negative signaling pathways including AMP-activated protein kinase (AMPK) and SH2 tyrosine phosphatase-1 (SHP-1). The knockdown of AMPK or SHP-1 with specific siRNA diminished the inhibitory effects of thalidomide on BMMC activation. By contrast, the knockdown of cereblon (CRBN), which is the primary target protein of thalidomide, augmented the effects of thalidomide. Thalidomide reduced the interactions of CRBN with Syk and AMPK promoted by FcεRI crosslinking, thereby relieving the suppression of AMPK signaling and suppressing Syk signaling. Furthermore, oral thalidomide treatment suppressed the PCA reaction in mice. In conclusion, thalidomide suppresses FcεRI-mediated mast cell activation by activating the AMPK and SHP-1 pathways and antagonizing the action of CRBN, indicating that it is a potential anti-allergic agent.

Keywords:  Src homology 2 domain-containing phosphatase-1; adenosine monophosphate-activated protein kinase; allergy; cereblon; mast cell; thalidomide

DOI:  https://doi.org/10.3390/cells12030469
Phytother Res. 2023 Feb 08.

Baicalin ameliorates high fat diet-induced nonalcoholic fatty liver disease in mice via adenosine monophosphate-activated protein kinase-mediated regulation of SREBP1/Nrf2/NF-κB signaling pathways.

Yanxia Gao, Jingbo Liu, Zhili Hao, Na Sun, Jianhua Guo, Xiaozhong Zheng, Panpan Sun, Wei Yin, Kuohai Fan, Hongquan Li.

  Nonalcoholic fatty liver disease (NAFLD) is a prevalent chronic liver disease around the world, imposing severe threats on human health. Unfortunately, no clinically approved drugs are available for use as yet. Baicalin (BA) is reported to have hepatoprotective effects, and it is not clear whether BA can treat NAFLD and how. Here, a high-fat diet (HFD)-induced NAFLD mouse model was established to explore the protective roles and mechanisms of BA against HFD-induced NAFLD. Physiochemical results showed that BA exhibited significantly protective effects against HFD-induced NAFLD in mice. Liver transcriptomic analysis revealed that BA attenuated HFD-induced NAFLD via activating AMPK pathway, which was confirmed by the AMPK inhibitor Compound C. Additionally, the expression changes of AMPK downstream genes demonstrated that BA exerted ameliorative effects against NAFLD through AMPK-mediated inhibition of SREBP1 and NF-κB pathways, and activation of Nrf2 pathway. Taken together, our study reveals the protective roles of BA against HFD-caused NAFLD through AMPK-mediated modulation of SREBP1/Nrf2/NF-κB pathways, suggesting that BA has potential drug development implications. Most importantly, our study creates a paradigm through the combination of molecular biology and bioinformatics for further studies of action mechanisms of biomolecules combating diseases.

Keywords:  AMPK; Baicalin; SREBP1/Nrf2/NF-κB pathways; high fat diet; nonalcoholic fatty liver disease

DOI:  https://doi.org/10.1002/ptr.7762
Elife. 2023 Feb 07. pii: e84319. [Epub ahead of print]12

Snf1/AMPK fine-tunes TORC1 signaling in response to glucose starvation.

Marco Caligaris, Raffaele Nicastro, Zehan Hu, Farida Tripodi, Johannes Erwin Hummel, Benjamin Pillet, Marie-Anne Deprez, Joris Winderickx, Sabine Rospert, Paola Coccetti, Jörn Dengjel, Claudio De Virgilio.

  The AMP-activated protein kinase (AMPK) and the target of rapamycin complex 1 (TORC1) are central kinase modules of two opposing signaling pathways that control eukaryotic cell growth and metabolism in response to the availability of energy and nutrients. Accordingly, energy depletion activates AMPK to inhibit growth, while nutrients and high energy levels activate TORC1 to promote growth. Both in mammals and lower eukaryotes such as yeast, the AMPK and TORC1 pathways are wired to each other at different levels, which ensures homeostatic control of growth and metabolism. In this context, a previous study (Hughes Hallet et. al, 2015) reported that AMPK in yeast, i.e. Snf1, prevents the transient TORC1 reactivation during the early phase following acute glucose starvation, but the underlying mechanism has remained elusive. Using a combination of unbiased mass spectrometry (MS)-based phosphoproteomics, genetic, biochemical, and physiological experiments, we show here that Snf1 temporally maintains TORC1 inactive in glucose-starved cells primarily through the TORC1-regulatory protein Pib2. Our data, therefore, extend the function of Pib2 to a hub that integrates both glucose and, as reported earlier, glutamine signals to control TORC1. We further demonstrate that Snf1 phosphorylates the TORC1 effector kinase Sch9 within its N-terminal region and thereby antagonizes the phosphorylation of a C-terminal TORC1-target residue within Sch9 itself that is critical for its activity. The consequences of Snf1-mediated phosphorylation of Pib2 and Sch9 are physiologically additive and sufficient to explain the role of Snf1 in short-term inhibition of TORC1 in acutely glucose-starved cells.

Keywords:  S. cerevisiae; biochemistry; cell biology; chemical biology

DOI:  https://doi.org/10.7554/eLife.84319
PLoS One. 2023 ;18(2): e0281718

Metformin regulates myoblast differentiation through an AMPK-dependent mechanism.

Eleonora Maniscalco, Giuliana Abbadessa, Magalì Giordano, Loredana Grasso, Paolo Borrione, Silvia Racca.

This study aims to investigate how metformin (Met) affects muscle tissue by evaluating the drug effects on proliferating, differentiating, and differentiated C2C12 cells. Moreover, we also investigated the role of 5'-adenosine monophosphate-activated protein kinase (AMPK) in the mechanism of action of Met. C2C12 myoblasts were cultured in growth medium with or without Met (250μM, 1mM and 10mM) for different times. Cell proliferation was evaluated by MTT assay, while cell toxicity was assessed by Trypan Blue exclusion test and Lactate Dehydrogenase release. Fluorescence Activated Cell Sorting analysis was performed to study cell cycle. Differentiating myoblasts were incubated in differentiation medium (DM) with or without 10mM Met. For experiments on myotubes, C2C12 were induced to differentiate in DM, and then treated with Met at scalar concentrations and for different times. Western blotting was performed to evaluate the expression of proteins involved in myoblast differentiation, muscle function and metabolism. In differentiating C2C12, Met inhibited cell differentiation, arrested cell cycle progression in G2/M phase and reduced the expression of cyclin-dependent kinase inhibitor 1. These effects were accompanied by activation of AMPK and modulation of the myogenic regulatory factors. Comparable results were obtained in myotubes. The use of Compound C, a specific inhibitor of AMPK, counteracted the above-mentioned Met effects. We reported that Met inhibits C2C12 differentiation probably by blocking cell-cycle progression and preventing cells permanent exit from cell-cycle. Moreover, our study provides solid evidence that most of the effects of Met on myoblasts and myotubes are mediated by AMPK.

DOI: https://doi.org/10.1371/journal.pone.0281718
ChemMedChem. 2023 Feb 07.

Imidazo[1,2-a]pyridine Derivatives as AMPK Activators: Synthesis, Structure-Activity Relationships, and Regulation of Reactive Oxygen Species in Renal Fibroblasts.

Siming Wu, Zhihong Xiao, Junling Wei, Lei Zhang, Yuanyuan Cao, Zhuo Chen, Qianbin Li, Gaoyun Hu.

  Adenosine 5'-monophosphate activated protein kinase (AMPK) has emerged as a promising target for the discovery of drugs to treat diabetic nephropathy (DN). Herein, a series of imidazo[1,2-a]pyridines were designed and synthesized. Among them, the active compound (EC50 = 11.0 nM) showed good enzyme activation and molecular docking results showed hydrogen bonding interactions with the key amino acids Asn111 and Lys29 in the active site. Meanwhile, further cellular level experiments revealed that it could reduce reactive oxygen species (ROS) levels in NRK-49F cells induced by high glucose, and Western Blot experiments also demonstrate that it can increase the levels of p-AMPK and p-ACC and decrease the levels of TGF-β1. The results of this study extend the structural types of AMPK activators and provide novel lead compounds for the subsequent development.

Keywords:  AMPK, activators, Imidazo[1,2-a]pyridines, Renal Fibroblasts, ROS

DOI:  https://doi.org/10.1002/cmdc.202200696
Clin Exp Immunol. 2023 Feb 06. pii: uxad016. [Epub ahead of print]

Effect and mechanisms of dexmedetomidine combined with macrophage migration inhibitory factor inhibition on the expression of inflammatory factors and AMPK in mice.

Siyu Chen, Jianjiang Wu, Aimei Li, Yidan Huang, Taiwangu Tailaiti, Tiantian Zou, Jin Jiang, Jiang Wang.

  Reperfusion after acute myocardial infarction can cause ischemia/reperfusion (I/R) injury, which not only impedes restoration of the functions of tissues and organs, but may also aggravate structural tissue and organ damage and dysfunction, worsening the patient's condition. Thus, the mechanisms that underpin myocardial I/R injury need to be better understood. We aimed to examine the effect of dexmedetomidine on macrophage migration inhibitory factor (MIF) in cardiomyocytes from mice with myocardial I/R injury and to explore the mechanistic role of adenosine 5'-monophosphate-activated protein kinase (AMPK) signaling in this process. Myocardial I/R injury was induced in mice. The expression of serum inflammatory factors, reactive oxygen species (ROS), adenosine triphosphate (ATP), and AMPK pathway-related proteins, as well as myocardial tissue structure and cell apoptosis rate, were compared between mice with I/R injury only; mice with I/R injury treated with dexmedetomidine, ISO-1 (MIF inhibitor), or both; and sham-operated mice. Dexmedetomidine reduced serum interleukin (IL)-6 and tumor necrosis factor-α concentrations and increased IL-10 concentration in mice with I/R injury. Moreover, dexmedetomidine reduced myocardial tissue ROS content and apoptosis rate and increased ATP content and MIF expression. MIF inhibition using ISO-1 reversed the protective effect of dexmedetomidine on myocardial I/R injury and reduced AMPK phosphorylation. Dexmedetomidine reduces the inflammatory response in mice with I/R injury and improves adverse symptoms, and its mechanism of action may be related to the MIF-AMPK pathway.

Keywords:  AMPK; ISO-1; MIF inhibitor; dexmedetomidine; verification response

DOI:  https://doi.org/10.1093/cei/uxad016
Pharm Biol. 2023 Dec;61(1): 362-371

Kazinol B protects H9c2 cardiomyocytes from hypoxia/reoxygenation-induced cardiac injury by modulating the AKT/AMPK/Nrf2 signalling pathway.

Qian Zhang, Yuan-Ye Dang, Xiu Luo, Ji-Jun Fu, Zhi-Cong Zou, Xue-Jing Jia, Guo-Dong Zheng, Chu-Wen Li.

   CONTEXT: Kazinol B (KB), an isoprenylated flavan derived from Broussonetia kazinoki Sieb. (Moraceae) root, has long been used in folk medicine.
OBJECTIVE: This study examines the protective effects of KB and its underlying mechanisms in hypoxia and reoxygenation (H/R)-induced cardiac injury in H9c2 rat cardiac myoblasts.
MATERIALS AND METHODS: H9c2 cells were incubated with various concentrations of KB (0, 0.3, 1, 3, 10 and 30 μM) for 2 h and then subjected to H/R insults. The protective effects of KB and its underlying mechanisms were explored.
RESULTS: KB significantly elevated cell viability (1 μM, 1.21-fold; 3 μM, 1.36-fold, and 10 μM, 1.47-fold) and suppressed LDH release (1 μM, 0.77-fold; 3 μM, 0.68-fold, and 10 μM, 0.59-fold) in H/R-induced H9c2 cells. Further, 10 μM KB blocked apoptotic cascades, as shown by the Annexin-V/PI (0.41-fold), DNA fragmentation (0.51-fold), caspase-3 (0.52-fold), PARP activation (0.27-fold) and Bax/Bcl-2 expression (0.28-fold) assays. KB (10 μM) downregulated reactive oxygen species production (0.51-fold) and lipid peroxidation (0.48-fold); it upregulated the activities of GSH-Px (2.08-fold) and SOD (1.72-fold). KB (10 μM) induced Nrf2 nuclear accumulation (1.94-fold) and increased ARE promoter activity (2.15-fold), HO-1 expression (3.07-fold), AKT (3.07-fold) and AMPK (3.07-fold) phosphorylation. Nrf2 knockdown via using Nrf2 siRNA abrogated KB-mediated protective effects against H/R insults. Moreover, pharmacological inhibitors of AKT and AMPK also abrogated KB-induced Nrf2 activation and its protective function.
DISCUSSION AND CONCLUSIONS: KB prevented H/R-induced cardiomyocyte injury via modulating the AKT and AMPK-mediated Nrf2 induction. KB might be a promising drug candidate for managing ischemic cardiac disorders.

Keywords:  Broussonetia kazinoki; apoptosis; mitochondrial dysfunction; myocardial ischemia; oxidative stress

DOI:  https://doi.org/10.1080/13880209.2023.2173247
Int J Mol Sci. 2023 Jan 20. pii: 2112. [Epub ahead of print]24(3):

Deficiency of S100A9 Alleviates Sepsis-Induced Acute Liver Injury through Regulating AKT-AMPK-Dependent Mitochondrial Energy Metabolism.

Yanting Zhang, Feng Wu, Fei Teng, Shubin Guo, Huihua Li.

  Acute liver injury (ALI) is recognized as a serious complication of sepsis in patients in intensive care units (ICUs). S100A8/A9 is known to promote inflammation and immune responses. However, the role of S100A8/A9 in the regulation of sepsis-induced ALI remains known. Our results indicated that S100A8/A9 expression was significantly upregulated in the livers of septic mice 24 h after cecal ligation and a puncture (CLP) operation. Moreover, S100A9-KO in mice markedly attenuated CLP-induced liver dysfunction and injury, promoting the AMPK/ACC/GLUT4-mediated increases in fatty acid and glucose uptake as well as the improvement in mitochondrial function and ATP production. In contrast, treatment with the AMPK inhibitor Compound C reversed the inhibitory effects of S100A9 KO on CLP-induced liver dysfunction and injury in vivo. Finally, the administration of the S100A9 inhibitor Paquinimod (Paq) to WT mice protected against CLP-induced mortality, liver injury and mitochondrial dysfunction. In summary, our findings demonstrate for the first time that S100A9 plays an important pro-inflammatory role in sepsis-mediated ALI by regulating AKT-AMPK-dependent mitochondrial energy metabolism and highlights that targeting S100A9 may be a promising new approach for the prevention and treatment of sepsis-related liver injury.

Keywords:  AMPK; S100A9; acute liver injury; mitochondrial energy metabolism; sepsis

DOI:  https://doi.org/10.3390/ijms24032112
Sci Rep. 2023 Feb 04. 13(1): 2045

Caloric restriction increases the resistance of aged heart to myocardial ischemia/reperfusion injury via modulating AMPK-SIRT1-PGC1a energy metabolism pathway.

Zhijia Guo, Meng Wang, Xiaodong Ying, Jiyu Yuan, Chenggang Wang, Wenjie Zhang, Shouyuan Tian, Xiaoyan Yan.

A large number of data suggest that caloric restriction (CR) has a protective effect on myocardial ischemia/reperfusion injury (I/R) in the elderly. However, the mechanism is still unclear. In this study, we created the I/R model in vivo by ligating the mice left coronary artery for 45 min followed by reperfusion. C57BL/6J wild-type mice were randomly divided into a young group fed ad libitum (y-AL), aged fed ad libitum (a-AL) and aged calorie restriction group (a-CR, 70% diet restriction), and fed for 6 weeks. The area of myocardial infarction was measured by Evan's blue-TTC staining, plasma cholesterol content quantified by ELISA, fatty acids and glucose measured by Langendorff working system, as well as protein expression of AMPK/SIRT1/PGC1a signaling pathway related factors in myocardial tissue detected by immunoblotting. Our results showed that CR significantly reduced infarct size in elderly mice after I/R injury, promoted glycolysis regardless of I/R injury, and restored myocardial glucose uptake in elderly mice. Compared with a-AL group, CR significantly promoted the expression of p-AMPK, SIRT1, p-PGC1a, and SOD2, but decreased PPARγ expression in aged mice. In conclusion, our results suggest that CR protects elderly mice from I/R injury by altering myocardial substrate energy metabolism via the AMPK/SIRT1/PGC1a pathway.

DOI: https://doi.org/10.1038/s41598-023-27611-6
PLoS One. 2023 ;18(2): e0280792

Mutation of regulatory phosphorylation sites in PFKFB2 does not affect the anti-fibrotic effect of metformin in the kidney.

Geoff Harley, Marina Katerelos, Kurt Gleich, Mardiana Lee, Peter F Mount, David A Power.

The anti-fibrotic effect of metformin has been widely demonstrated. Fibrosis in the kidney after injury is associated with reduced expression of genes involved in both fatty acid and glycolytic energy metabolism. We have previously reported that the anti-fibrotic effect of metformin requires phosphoregulation of fatty acid oxidation by AMP-activated protein kinase (AMPK). To determine whether metformin also acts via regulation of glycolysis, we mutated regulatory phosphosites in the PFKFB2 isoform of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB2), a key regulator of glycolysis in the kidney. Mice with inactivating knockin (KI) mutations of the phosphorylation sites in PFKFB2 (PFKFB2 KI mice), which reduces the ability to increase the rate of glycolysis following stimulation, were used. Metformin was administered via drinking water to mice with a unilateral ureteric obstruction (UUO) model of renal fibrosis. In the PFKFB2 KI mice treated with metformin, there was decreased fibrosis and macrophage infiltration following UUO as assessed by Western blot for fibronectin and RT-PCR for α-smooth muscle actin, collagen 3, and F4.80, and confirmed by histology. Expression of the inducible PFKFB3 isoform was increased with metformin in UUO in both WT and PFKFB2 KI mice. There was no significant difference between WT and PFKFB2 KI mice treated with metformin in the degree of fibrosis following UUO in any of the Western blot or RT-PCR parameters that were measured. These data show that inhibition of the regulation of glycolysis by PFKFB2 does not diminish the anti-fibrotic effect of metformin in a model of renal fibrosis.

DOI: https://doi.org/10.1371/journal.pone.0280792
Life Sci. 2023 Feb 04. pii: S0024-3205(23)00105-4. [Epub ahead of print] 121471

Naringin protects mice from D-galactose-induced lung aging and mitochondrial dysfunction: Implication of SIRT1 pathways.

Abeer A A Salama, Noha N Yassen, Heba M Mansour.

   AIM: Aging is the leading risk factor for diminishing lung function, as well as injury and lung disorder. The target of our research was to examine the potential protective effect of naringin and the possible role of SIRT1 in mice with D-galactose-induced lung aging, by evaluating its effects on antioxidant systems, mitochondrial biogenesis, autophagy, and apoptosis, by referring to the potential involvement of Nrf2/NQO1, LKB1/AMPK/PGC-1α, FOXO1, and P53/caspase-3 signaling.
MATERIAL AND METHODS: The mice were randomly sorted into 5 groups (10 each): 1st: normal group received subcutaneous normal saline and intragastric distilled water, 2nd: naringin 300 mg/kg orally, 3rd: D-galactose (200 mg/kg/day) was administered subcutaneously into mice for eight weeks, to accelerate aging, 4th & 5th: oral naringin (150, 300 mg/kg) was given daily concurrently with D-galactose injection for 8 weeks.
KEY FINDING: In silico investigation revealed that naringin substantially stimulates the SIRT1 and AMPK molecules. At the molecular level, our findings indicated that treatment with naringin stimulated the mitochondrial biogenesis pathway through regulation of the LKB1/AMPK/PGC-1α signals and upregulated FOXO1-mediated autophagy. Furthermore, naringin exhibited antioxidant properties by activating the Nrf2/NQO1 pathway and inhibiting MDA and AGEs levels. In addition, Naringin ameliorated alveolar spaces destruction and bronchial wall thickening, as well as alleviated P53/caspase-3 apoptosis signaling.
SIGNIFICANCE: Naringin exerts protective effects against D-galactose-induced lung aging and enhances longevity by activating SIRT1. SIRT1 regulates various aging-related molecular pathways via restoring pro-oxidant/antioxidant homeostasis, activation of mitochondrial biogenesis, modulating of autophagy and inhibition of apoptosis.

Keywords:  AMPK; Lung aging; Mitochondrial dysfunction; Naringin; Nrf2; SIRT1

DOI:  https://doi.org/10.1016/j.lfs.2023.121471
Biotech Histochem. 2023 Feb 06. 1-10

Effects of diazoxide on streptozotocin induced β cell damage via HSP70/HSP90/TLR4/AMPK signaling pathways.

Salih Tunc Kaya.

  I investigated the effects of diazoxide, a mitochondrial potassium channel opener, on streptozotocin (STZ) induced pancreatic β cell damage via the HSP70/HSP90/TLR4/AMPK signaling pathways in vitro. I used the pancreatic β cell line, 1.1B4, to create four groups: control, STZ treated, diazoxide treated, STZ + diazoxide treated. The STZ treated cells were exposed to 20 µM STZ for 2 h with or without 100 µM diazoxide for 24 h. Total antioxidant status (TAS), total oxidant status (TOS), cell viability and mitochondrial membrane potential (MMP) were measured. Expression of ATP-sensitive potassium channel (KATP) subunits, heat shock protein-70 (HSP70), heat shock protein-90 (HSP90), toll-like receptor 4 (TLR4), AMP-activated protein kinase (AMPK) and some apoptotic proteins were detected using western blotting. Apoptosis was assessed using TUNEL staining. STZ increased TOS and OSI in the pancreatic β cells; however, diazoxide failed to improve oxidative stress. Also, STZ increased tunnel positive cells in the pancreatic β cells. Diazoxide decreased the tunnel positive cells in the STZ treated β cell. STZ decreased MMP; however, diazoxide did not normalize MMP in the STZ induced β cells. Diazoxide increased the HSP70:HSP90 protein expression ratio. STZ decreased expression of AMPK and subunits of KATP channel and increased the expression of caspase-3 and TLR4 protein; diazoxide normalized the expression of all proteins studied. KATP channel opening by diazoxide protects pancreatic β cells against STZ toxicity via HSP70/HSP90/TLR4/AMPK signaling.

Keywords:  ATP; HSP70; HSP90; diabetes; diazoxide; human; potassium channel; streptozotocin

DOI:  https://doi.org/10.1080/10520295.2023.2168757
Front Immunol. 2022 ;13 1051045

Vam6 reduces iNKT cell function in tumor via modulating AMPK/mTOR pathways.

Shiyu Bai, Qielan Wu, Shasha Zhu, Yuwei Zhang, Xuran Chen, Miya Su, Jun Pan, Shuhang Li, Ting Yue, Linfeng Xu, Di Xie, Chenxi Tian, Dan Zhao, Xiang Li, Junjie Hou, Lu Wang, Sicheng Fu, Yanhong Xue, Amin Jiang, Dong Li, Tao Xu, Zhigang Tian, Rongbin Zhou, Huimin Zhang, Li Bai.

  Activation of mTORC1 is essential for anti-tumor function of iNKT cells. The mechanisms underlying impaired mTORC1 activation in intratumoral iNKT cells remain unclear. Via generating Vam6+/- mice and using flow cytometry, image approach, and RNA sequencing, we studied the role of Vam6 in controlling mTORC1 activation and intratumoral iNKT cell functions. Here, we find that increased Vam6 expression in intratumoral iNKT cells leads to impaired mTORC1 activation and IFN-γ production. Mechanistically, Vam6 in iNKT cells is essential for Rab7a-Vam6-AMPK complex formation and thus for recruitment of AMPK to lysosome to activate AMPK, a negative regulator of mTORC1. Additionally, Vam6 relieves inhibitory effect of VDAC1 on Rab7a-Vam6-AMPK complex formation at mitochondria-lysosome contact site. Moreover, we report that lactic acid produced by tumor cells increases Vam6 expression in iNKT cells. Given the key roles of increased Vam6 in promoting AMPK activation in intratumoral iNKT cells, reducing Vam6 expression signifificantly enhances the mTORC1 activation in intratumoral iNKT cells as well as their anti-tumor effificacy. Together, we propose Vam6 as a target for iNKT cell-based immunotherapy.

Keywords:  AMPK; Rab7a-Vam6-AMPK complex; Vam6; iNKT cells; mTORC1

DOI:  https://doi.org/10.3389/fimmu.2022.1051045
Mol Biol Rep. 2023 Feb 11.

Metformin alleviates ethanol-induced cardiomyocyte injury by activating AKT/Nrf2 signaling in an ErbB2-dependent manner.

Yunjie Chen, Suyan Zhu, Zhu Lin, Yuanbin Zhang, Cheng Jin, Shengqu He, Xueqin Chen, Xuan Zhou.

   BACKGROUND: Metformin, a first-line oral anti-diabetic drug, has recently been reported to exert protective effect on various cardiovascular diseases. However, the potential role of metformin in ethanol-induced cardiomyocyte injury is still unknown. Therefore, this study was aimed to investigate the effect of metformin on ethanol-induced cardiomyocyte injury and its underlying mechanism.
METHODS AND RESULTS: H9c2 cardiomyocytes were exposed to ethanol for 24 h to establish an ethanol-induced cardiomyocyte injury model, and followed by treatment with metformin in the presence or absence of Lapatinib (an ErbB2 inhibition). CCK8 and LDH assays demonstrated that metformin improved cell viability in cardiomyocytes exposed to ethanol. Furthermore, metformin suppressed cardiomyocyte apoptosis and reduced the expressions of apoptosis-related proteins (Bax and C-CAS-3). In addition, our results showed that metformin activated the AKT/Nrf2 pathway, and then promoted Nrf2 nuclear translocation and the transcription of its downstream antioxidant genes (HO-1, CAT and SOD2), thereby inhibiting oxidative stress. Interestingly, we found that ErbB2 protein expression was significantly inhibited in ethanol-treated cardiomyocytes, which was markedly reversed by metformin. In contrast, Lapatinib largely abrogated the activation of AKT/Nrf2 signaling by metformin, accompanied by the increases in oxidative stress and cardiomyocyte apoptosis, indicating that metformin prevented ethanol-induced cardiomyocyte injury in an ErbB2-dependent manner.
CONCLUSION: In summary, our study provides the first evidence that metformin protects cardiomyocyte against ethanol-induced oxidative stress and apoptosis by activating ErbB2-mediated AKT/Nrf2 signaling. Thus, metformin may be a potential novel treatment approach for alcoholic cardiomyopathy.

Keywords:  Alcoholic cardiomyopathy; Cardiomyocyte; ErbB2; Metformin; Nrf2; Oxidative stress

DOI:  https://doi.org/10.1007/s11033-023-08310-x