bims-amsmem 2023-04-16 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2023–04–16
seventeen papers selected by
Dipsikha Biswas, Københavns Universitet

Activation of AMPK promotes cardiac differentiation by stimulating the autophagy pathway.
AMPK targets a proto-oncogene TPD52 (isoform 3) expression and its interaction with LKB1 suppress AMPK-GSK3β signaling axis in prostate cancer.
Germline stem cell integrity and quiescence are controlled by an AMPK-dependent neuronal trafficking pathway.
Elevated basal AMP-activated protein kinase activity sensitizes colorectal cancer cells to growth inhibition by metformin.
AMPK reduces macrophage endotoxin tolerance through inhibition of TGF-β1 production and its signaling pathway.
HSP90 inhibition in the mouse spinal cord enhances opioid signaling by suppressing an AMPK-mediated negative feedback loop.
Uncarboxylated Osteocalcin Decreases SCD1 by Activating AMPK to Alleviate Hepatocyte Lipid Accumulation.
The Protective Effect of 11-Keto-β-Boswellic Acid against Diabetic Cardiomyopathy in Rats Entails Activation of AMPK.
Differentiation-inducing factor 1 activates cofilin through pyridoxal phosphatase and AMP-activated protein kinase, resulting in mitochondrial fission.
Intermittent Fasting Activates AMP-Kinase to Restructure Right Ventricular Lipid Metabolism and Microtubules.
LTF Induces Radioresistance by Promoting Autophagy and Forms an AMPK/SP2/NEAT1/miR-214-5p Feedback Loop in Lung Squamous Cell Carcinoma.
6-Gingerol Ameliorates Hepatic Steatosis, Inflammation and Oxidative Stress in High-Fat Diet-Fed Mice through Activating LKB1/AMPK Signaling.
Metformin and HER2-positive breast cancer: Mechanisms and therapeutic implications.
Melatonin protects against developmental PBDE-47 neurotoxicity by targeting the AMPK/mitophagy axis.
Lactobacillus plantarum postbiotics trigger AMPK-dependent autophagy to suppress Salmonella intracellular infection and NLRP3 inflammasome activation.
Neferine ameliorates nonalcoholic steatohepatitis through regulating AMPK pathway.
Constitutively activated AMPKα1 protects against skeletal aging in mice by promoting bone-derived IGF-1 secretion.

J Cell Commun Signal. 2023 Apr 11.

Activation of AMPK promotes cardiac differentiation by stimulating the autophagy pathway.

Mina Kolahdouzmohammadi, Sara Pahlavan, Fattah Sotoodehnejadnematalahi, Yaser Tahamtani, Mehdi Totonchi.

  Autophagy, a critical catabolic process for cell survival against different types of stress, has a role in the differentiation of various cells, such as cardiomyocytes. Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is an energy-sensing protein kinase involved in the regulation of autophagy. In addition to its direct role in regulating autophagy, AMPK can also influence other cellular processes by regulating mitochondrial function, posttranslational acetylation, cardiomyocyte metabolism, mitochondrial autophagy, endoplasmic reticulum stress, and apoptosis. As AMPK is involved in the control of various cellular processes, it can influence the health and survival of cardiomyocytes. This study investigated the effects of an AMPK inducer (Metformin) and an autophagy inhibitor (Hydroxychloroquine) on the differentiation of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs). The results showed that autophagy was upregulated during cardiac differentiation. Furthermore, AMPK activation increased the expression of CM-specific markers in hPSC-CMs. Additionally, autophagy inhibition impaired cardiomyocyte differentiation by targeting autophagosome-lysosome fusion. These results indicate the significance of autophagy in cardiomyocyte differentiation. In conclusion, AMPK might be a promising target for the regulation of cardiomyocyte generation by in vitro differentiation of pluripotent stem cells.

Keywords:  AMPK; Autophagy; Cardiomyocyte differentiation; Hydroxychloroquine; Metformin

DOI:  https://doi.org/10.1007/s12079-023-00744-z
J Cell Commun Signal. 2023 Apr 11.

AMPK targets a proto-oncogene TPD52 (isoform 3) expression and its interaction with LKB1 suppress AMPK-GSK3β signaling axis in prostate cancer.

Priyanka Khilar, K K Sruthi, Sakkarai Mohamed Asha Parveen, Sirisha Natani, Surender Singh Jadav, Ramesh Ummanni.

  Tumor protein D52 (TPD52) is a proto-oncogene overexpressed in prostate cancer (PCa) due to gene amplification and it is involved in the cancer progression of many cancers including PCa. However, the molecular mechanisms underlying the role of TPD52 in cancer progression are still under investigation. In this study, we report that the activation of AMP-activated protein kinase (AMPK) by AICAR (5-Aminoimidazole-4-carboxamide ribonucleotide) inhibited the LNCaP and VCaP cells growth by silencing TPD52 expression. Activation of AMPK inhibited the proliferation and migration of LNCaP and VCaP cells. Interestingly, AICAR treatment to LNCaP and VCaP cells led to the downregulation of TPD52 via activation of GSK3β by a decrease of inactive phosphorylation at Ser9. Moreover, in AICAR treated LNCaP cells, inhibition of GSK3β by LiCl attenuated downregulation of TPD52 indicating that AICAR acts via GSK3β. Furthermore, we found that TPD52 interacts with serine/threonine kinase 11 or Liver kinase B1 (LKB1) a known tumor suppressor and an upstream kinase for AMPK. The molecular modeling and MD simulations indicates that the interaction between TPD52 and LKB1 leads to inhibition of the kinase activity of LKB1 as its auto-phosphorylation sites were masked in the complex. Consequently, TPD52-LKB1 interaction may lead to inactivation of AMPK. Moreover, overexpression of TPD52 is found to be responsible for the reduction of pLKB1 (Ser428) and pAMPK (Thr172). Therefore, TPD52 may be playing its oncogenic role via suppressing the AMPK activation. Altogether, our results revealed a new mechanism of PCa progression in which TPD52 overexpression inhibits AMPK activation by interacting with LKB1. These results support that the use of AMPK activators and/or small molecules that could disrupt the TPD52-LKB1 interaction might be useful to suppress PCa cell growth. TPD52 interacts LKB1 and interfere with activation of AMPK in PCa cells.

Keywords:  AMP-activated protein kinase; Cell proliferation; Liver kinase B1; Prostate cancer; Protein–protein interactions; TPD52 (isoform 3)

DOI:  https://doi.org/10.1007/s12079-023-00745-y
PLoS Genet. 2023 Apr 14. 19(4): e1010716

Germline stem cell integrity and quiescence are controlled by an AMPK-dependent neuronal trafficking pathway.

Christopher Wong, Pratik Kadekar, Elena Jurczak, Richard Roy.

During periods of energetic stress, Caenorhabditis elegans can execute a developmentally quiescent stage called "dauer", during which all germline stem cells undergo a G2 cell cycle arrest. In animals that lack AMP-activated protein kinase (AMPK) signalling, the germ cells fail to arrest, undergo uncontrolled proliferation, and lose their reproductive capacity upon recovery from this quiescent stage. These germline defects are accompanied by, and likely result from, an altered chromatin landscape and gene expression program. Through genetic analysis we identified an allele of tbc-7, a predicted RabGAP protein that functions in the neurons, which when compromised, suppresses the germline hyperplasia in the dauer larvae, as well as the post-dauer sterility and somatic defects characteristic of AMPK mutants. This mutation also corrects the abundance and aberrant distribution of transcriptionally activating and repressive chromatin marks in animals that otherwise lack all AMPK signalling. We identified RAB-7 as one of the potential RAB proteins that is modulated by tbc-7 and show that the activity of RAB-7 is critical for the maintenance of germ cell integrity during the dauer stage. We reveal that TBC-7 is regulated by AMPK through two mechanisms when the animals enter the dauer stage. Acutely, the AMPK-mediated phosphorylation of TBC-7 reduces its activity, potentially by autoinhibition, thereby preventing the inactivation of RAB-7. In the more long term, AMPK regulates the miRNAs mir-1 and mir-44 to attenuate tbc-7 expression. Consistent with this, animals lacking mir-1 and mir-44 are post-dauer sterile, phenocopying the germline defects of AMPK mutants. Altogether, we have uncovered an AMPK-dependent and microRNA-regulated cellular trafficking pathway that is initiated in the neurons, and is critical to control germline gene expression cell non-autonomously in response to adverse environmental conditions.

DOI: https://doi.org/10.1371/journal.pgen.1010716
Open Biol. 2023 Apr;13(4): 230021

Elevated basal AMP-activated protein kinase activity sensitizes colorectal cancer cells to growth inhibition by metformin.

Kaitlin R Morrison, Tingting Wang, Kuan Yoow Chan, Eleanor W Trotter, Ari Gillespie, Michael Z Michael, Jonathan S Oakhill, Iain M Hagan, Janni Petersen.

  Expression and activity of the AMP-activated protein kinase (AMPK) α1 catalytic subunit of the heterotrimeric kinase significantly correlates with poor outcome for colorectal cancer patients. Hence there is considerable interest in uncovering signalling vulnerabilities arising from this oncogenic elevation of AMPKα1 signalling. We have therefore attenuated mammalian target of rapamycin (mTOR) control of AMPKα1 to generate a mutant colorectal cancer in which AMPKα1 signalling is elevated because AMPKα1 serine 347 cannot be phosphorylated by mTORC1. The elevated AMPKα1 signalling in this HCT116 α1.S347A cell line confers hypersensitivity to growth inhibition by metformin. Complementary chemical approaches confirmed this relationship in both HCT116 and the genetically distinct HT29 colorectal cells, as AMPK activators imposed vulnerability to growth inhibition by metformin in both lines. Growth inhibition by metformin was abolished when AMPKα1 kinase was deleted. We conclude that elevated AMPKα1 activity modifies the signalling architecture in such a way that metformin treatment compromises cell proliferation. Not only does this mutant HCT116 AMPKα1-S347A line offer an invaluable resource for future studies, but our findings suggest that a robust biomarker for chronic AMPKα1 activation for patient stratification could herald a place for the well-tolerated drug metformin in colorectal cancer therapy.

Keywords:  AMPK; PRKAA1; colorectal cancers‌; mTORC1; metformin; α1.S347A

DOI:  https://doi.org/10.1098/rsob.230021
Int Immunopharmacol. 2023 Apr 08. pii: S1567-5769(23)00467-8. [Epub ahead of print]118 110146

AMPK reduces macrophage endotoxin tolerance through inhibition of TGF-β1 production and its signaling pathway.

Mei Yin, Joungmin Kim, Jeong-Il Choi, Joon-Suk Bom, Hong-Beom Bae, Seongtae Jeong.

  Adenosine monophosphate-activated protein kinase (AMPK) is involved in suppression of the development of endotoxin tolerance, which is a driver of the immunosuppression induced by sepsis. However, the mechanism by which AMPK inhibits the development of endotoxin tolerance has not been clearly elucidated. Therefore, the present study was performed to investigate the mechanism by which the AMPK activator, metformin, inhibits the development of endotoxin tolerance. Lipopolysaccharide (LPS) increased the production of transforming growth factor (TGF)-β1 in macrophages, which was inhibited by metformin and resveratrol. Knockdown of AMPKα1 inhibited the suppressive effect of metformin on LPS-induced TGF-β1 production. TGF-β neutralizing antibody and TGF-β type I receptor inhibitor increased the production of TNF-α and IL-6 via LPS restimulation in tolerized macrophages. LPS increased Smad2 phosphorylation, but this was inhibited in cells treated with TGF-β neutralizing antibody or metformin. Smad2 knockdown inhibited the development of endotoxin tolerance, as evidenced by increased TNF-α production in response to LPS restimulation in tolerized macrophages. TGF-β1 expression was increased, and the levels of TNF-α and IL-6 production induced by LPS stimulation were decreased, in splenocytes of cecal ligation and puncture (CLP) model mice compared to sham-operated controls. However, metformin treatment suppressed the production of TGF-β1, and enhanced the production of TNF-α and IL-6 induced by LPS stimulation in splenocytes of CLP mice. These results indicated that AMPK activation inhibits LPS-induced TGF-β1 production and its signaling pathway, thus suppressing the development of endotoxin tolerance in macrophages.

Keywords:  AMP-activated protein kinase; Lipopolysaccharide; Macrophage; Metformin; Tolerance

DOI:  https://doi.org/10.1016/j.intimp.2023.110146
Sci Signal. 2023 Apr 11. 16(780): eade2438

HSP90 inhibition in the mouse spinal cord enhances opioid signaling by suppressing an AMPK-mediated negative feedback loop.

Katherin A Gabriel, John M Streicher.

Opioids and other agonists of the μ-opioid receptor are effective at managing acute pain, but their chronic use can lead to tolerance that limits their efficacy. We previously reported that inhibiting the chaperone protein HSP90 in the spinal cords of mice promotes the antinociceptive effects of opioids in a manner that involved increased activation of the kinase ERK. Here, we found that the underlying mechanism involves the relief of a negative feedback loop mediated by the kinase AMPK. Intrathecal treatment of male and female mice with the HSP90 inhibitor 17-AAG decreased the abundance of the β1 subunit of AMPK in the spinal cord. The antinociceptive effects of 17-AAG with morphine were suppressed by intrathecal administration of AMPK activators and enhanced by an AMPK inhibitor. Opioid treatment increased the abundance of phosphorylated AMPK in the dorsal horn of the spinal cord, where it colocalized with a neuronal marker and the neuropeptide CGRP. Knocking down AMPK in CGRP-positive neurons enhanced the antinociceptive effects of morphine and demonstrated that AMPK mediated the signal transduction between HSP90 inhibition and ERK activation. These data suggest that AMPK mediates an opioid-induced negative feedback loop in CGRP neurons of the spinal cord and that this loop can be disabled by HSP90 inhibition to enhance the efficacy of opioids.

DOI: https://doi.org/10.1126/scisignal.ade2438
Molecules. 2023 Mar 31. pii: 3121. [Epub ahead of print]28(7):

Uncarboxylated Osteocalcin Decreases SCD1 by Activating AMPK to Alleviate Hepatocyte Lipid Accumulation.

Danqing Wang, Miao Zhang, Jiaojiao Xu, Jianhong Yang.

  Uncarboxylated osteocalcin (GluOC), a small-molecule protein specifically synthesized and secreted by osteoblasts, is important in the regulation of energy metabolism. In our previous study, GluOC was shown to be effective in ameliorating dyslipidemia and hepatic steatosis in KKAy mice. However, the underlying mechanism of GluOC action on hepatocytes has not been well validated. In this study, oleic acid/palmitic acid (OA/PA)-induced HepG2 and NCTC 1469 cells were used as non-alcoholic fatty liver disease (NAFLD) cell models, and triacylglycerol (TG) levels were measured by oil red O staining, Nile Red staining, and ELISA. The fatty acid synthesis-related protein expression was detected by real-time quantitative polymerase chain reaction, Western blotting, and immunofluorescence. The results show that GluOC reduced triglyceride levels, and decreased the expression of sterol regulatory element-binding protein-1c (SREBP-1c) and stearyl-coenzyme A desaturase 1 (SCD1). si-SCD1 mimicked the lipid accumulation-reducing effect of GluOC, while overexpression of SCD1 attenuated the effect of GluOC. In addition, GluOC activated AMP-activated protein kinase (AMPK) phosphorylation to affect lipid metabolism in hepatocytes. Overall, the results of this study suggest that GluOC decreases SCD1 by activating AMPK to alleviate hepatocyte lipid accumulation, which provides a new target for improving NAFLD in further research.

Keywords:  AMPK; SCD1; lipid accumulation; osteocalcin; signaling pathway

DOI:  https://doi.org/10.3390/molecules28073121
Nutrients. 2023 Mar 29. pii: 1660. [Epub ahead of print]15(7):

The Protective Effect of 11-Keto-β-Boswellic Acid against Diabetic Cardiomyopathy in Rats Entails Activation of AMPK.

Jozaa Z AlTamimi, Nora A AlFaris, Ghedeir M Alshammari, Reham I Alagal, Dalal H Aljabryn, Mohammed Abdo Yahya.

  This study examined the protective effect of 11-keto-β-boswellic acid (AKBA) against streptozotocin (STZ)-induced diabetic cardiomyopathy (DC) in rats and examined the possible mechanisms of action. Male rats were divided into 5 groups (n = 8/each): (1) control, AKBA (10 mg/kg, orally), STZ (65 mg/kg, i.p.), STZ + AKBA (10 mg/kg, orally), and STZ + AKBA + compound C (CC/an AMPK inhibitor, 0.2 mg/kg, i.p.). AKBA improved the structure and the systolic and diastolic functions of the left ventricles (LVs) of STZ rats. It also attenuated the increase in plasma glucose, plasma insulin, and serum and hepatic levels of triglycerides (TGs), cholesterol (CHOL), and free fatty acids (FFAs) in these diabetic rats. AKBA stimulated the ventricular activities of phosphofructokinase (PFK), pyruvate dehydrogenase (PDH), and acetyl CoA carboxylase (ACC); increased levels of malonyl CoA; and reduced levels of carnitine palmitoyltransferase I (CPT1), indicating improvement in glucose and FA oxidation. It also reduced levels of malondialdehyde (MDA); increased mitochondria efficiency and ATP production; stimulated mRNA, total, and nuclear levels of Nrf2; increased levels of glutathione (GSH), heme oxygenase (HO-1), superoxide dismutase (SOD), and catalase (CAT); but reduced the expression and nuclear translocation of NF-κB and levels of tumor-necrosis factor-α (TNF-α) and interleukin-6 (IL-6). These effects were concomitant with increased activities of AMPK in the LVs of the control and STZ-diabetic rats. Treatment with CC abolished all these protective effects of AKBA. In conclusion, AKBA protects against DC in rats, mainly by activating the AMPK-dependent control of insulin release, cardiac metabolism, and antioxidant and anti-inflammatory effects.

Keywords:  11-keto-β-boswellic acid; AMPK; Nrf2; diabetic cardiomyopathy; oxidative stress; streptozotocin

DOI:  https://doi.org/10.3390/nu15071660
J Pharmacol Sci. 2023 May;pii: S1347-8613(23)00011-7. [Epub ahead of print]152(1): 39-49

Differentiation-inducing factor 1 activates cofilin through pyridoxal phosphatase and AMP-activated protein kinase, resulting in mitochondrial fission.

Takeru Inoue, Koichi Miura, Ruzhe Han, Fumi Seto-Tetsuo, Masaki Arioka, Kazunobu Igawa, Katsuhiko Tomooka, Toshiyuki Sasaguri.

  Differentiation-inducing factor 1 (DIF-1) is a morphogen produced by Dictyostelium discoideum that inhibits the proliferation and migration of both D. discoideum and most mammalian cells. Herein, we assessed the effect of DIF-1 on mitochondria, because DIF-3, which is similar to DIF-1, reportedly localizes in the mitochondria when added exogenously, however the significance of this localization remains unclear. Cofilin is an actin depolymerization factor that is activated by dephosphorylation at Ser-3. By regulating the actin cytoskeleton, cofilin induces mitochondrial fission, the first step in mitophagy. Here, we report that DIF-1 activates cofilin and induces mitochondrial fission and mitophagy mainly using human umbilical vein endothelial cells (HUVECs). AMP-activated kinase (AMPK), a downstream molecule of DIF-1 signaling, is required for cofilin activation. Pyridoxal phosphatase (PDXP)-known to directly dephosphorylate cofilin-is also required for the effect of DIF-1 on cofilin, indicating that DIF-1 activates cofilin through AMPK and PDXP. Cofilin knockdown inhibits mitochondrial fission and decreases mitofusin 2 (Mfn2) protein levels, a hallmark of mitophagy. Taken together, these results indicate that cofilin is required for DIF-1- induced mitochondrial fission and mitophagy.

Keywords:  AMP-Activated kinase; Cofilin; Differentiation-inducing factor 1; Mitophagy; Pyridoxal phosphatase

DOI:  https://doi.org/10.1016/j.jphs.2023.02.009
JACC Basic Transl Sci. 2023 Mar;8(3): 239-254

Intermittent Fasting Activates AMP-Kinase to Restructure Right Ventricular Lipid Metabolism and Microtubules.

Felipe Kazmirczak, Lynn M Hartweck, Neal T Vogel, Jenna B Mendelson, Anna K Park, Rashmi M Raveendran, Jin O-Uchi, Bong Sook Jhun, Sasha Z Prisco, Kurt W Prins.

  Intermittent fasting (IF) extends life span via pleotropic mechanisms, but one important molecular mediator is adenosine monophosphate-activated protein kinase (AMPK). AMPK enhances lipid metabolism and modulates microtubule dynamics. Dysregulation of these molecular pathways causes right ventricular (RV) failure in patients with pulmonary arterial hypertension. In rodent pulmonary arterial hypertension, IF activates RV AMPK, which restores mitochondrial and peroxisomal morphology and restructures mitochondrial and peroxisomal lipid metabolism protein regulation. In addition, IF increases electron transport chain protein abundance and activity in the right ventricle. Echocardiographic and hemodynamic measures of RV function are positively associated with fatty acid oxidation and electron transport chain protein levels. IF also combats heightened microtubule density, which normalizes transverse tubule structure.

Keywords:  fatty acid oxidation; ferroptosis; microtubules; mitochondria; peroxisomes; right ventricular function

DOI:  https://doi.org/10.1016/j.jacbts.2022.12.001
Int J Biol Sci. 2023 ;19(5): 1509-1527

LTF Induces Radioresistance by Promoting Autophagy and Forms an AMPK/SP2/NEAT1/miR-214-5p Feedback Loop in Lung Squamous Cell Carcinoma.

Junmiao Wen, Wang Zheng, Liang Zeng, Boyan Wang, Donglai Chen, Yongbing Chen, Xueguan Lu, Chunlin Shao, Jiayan Chen, Min Fan.

  Radiotherapy is the most predominant treatment strategy for lung squamous cell carcinoma (LUSC) patients, but radioresistance is the major obstacle to therapy effectiveness. The mechanisms and regulators of LUSC radioresistance remain unclear. Here, lactotransferrin (LTF) is found to be significantly upregulated in radioresistant LUSC cell lines (H226R and H1703R) and clinical samples and promotes radioresistance of LUSC both in vitro and in vivo. Comprehensive enrichment analyses suggested that LTF potentially modulates autophagy in LUSC. Interestingly, the level of autophagy was raised in the radioresistant cells, and suppression of autophagy sensitized LUSC to irradiation. Functional experiments showed that LTF deficiency inhibits cellular autophagy through the AMPK pathway, ultimately leading to radiosensitization. Mechanistically, LTF can directly interact with AMPK to facilitate its phosphorylation and activate autophagy signaling. Moreover, NEAT1 functions as a ceRNA that targets miR-214-5p resulting in an increased LTF expression. Intriguingly, SP2, a transcription factor regulated by AMPK, induced NEAT1 expression by directly binding to its promoter region and thus forming a LTF/AMPK/SP2/NEAT1/miR-214-5p feedback loop. Our work reveals for the first time that LTF induces radioresistance by promoting autophagy and enhancing its self-expression via forming a positive feedback loop, suggesting that LTF is an appealing radiosensitization target for treating LUSC.

Keywords:  LTF; autophagy; lung cancer; radioresistance

DOI:  https://doi.org/10.7150/ijbs.78669
Int J Mol Sci. 2023 Mar 27. pii: 6285. [Epub ahead of print]24(7):

6-Gingerol Ameliorates Hepatic Steatosis, Inflammation and Oxidative Stress in High-Fat Diet-Fed Mice through Activating LKB1/AMPK Signaling.

Yuzhe Liu, Dong Li, Shang Wang, Ze Peng, Qi Tan, Qifeng He, Jianwei Wang.

  6-Gingerol, one of the major pharmacologically active ingredients extracted from ginger, has been reported experimentally to exert hepatic protection in non-alcoholic fatty liver disease (NAFLD). However, the molecular mechanism remains largely elusive. RNA sequencing indicated the significant involvement of the AMPK signaling pathway in 6-gingerol-induced alleviation of NAFLD in vivo. Given the significance of the LKB1/AMPK pathway in metabolic homeostasis, this study aims to investigate its role in 6-gingerol-induced mitigation on NAFLD. Our study showed that 6-gingerol ameliorated hepatic steatosis, inflammation and oxidative stress in vivo and in vitro. Further experiment validation suggested that 6-gingerol activated an LKB1/AMPK pathway cascade in vivo and in vitro. Co-immunoprecipitation analysis demonstrated that the 6-gingerol-elicited activation of an LKB1/AMPK pathway cascade was related to the enhanced stability of the LKB1/STRAD/MO25 complex. Furthermore, radicicol, an LKB1 destabilizer, inhibited the activating effect of 6-gingerol on an LKB1/AMPK pathway cascade via destabilizing LKB1/STRAD/MO25 complex stability in vitro, thus reversing the 6-gingerol-elicited ameliorative effect. In addition, molecular docking analysis further predicated the binding pockets of LKB1 necessary for binding with 6-gingerol. In conclusion, our results indicate that 6-gingerol plays an important role in regulating the stability of the LKB1/STRAD/MO25 complex and the activation of LKB1, which might weigh heavily in the 6-gingerol alleviation of NAFLD.

Keywords:  6-gingerol; AMPK; LKB1/STRAD/MO25; non-alcoholic fatty liver disease

DOI:  https://doi.org/10.3390/ijms24076285
Biomed Pharmacother. 2023 Apr 08. pii: S0753-3322(23)00464-X. [Epub ahead of print]162 114676

Metformin and HER2-positive breast cancer: Mechanisms and therapeutic implications.

Sara S Bashraheel, Hadeel Kheraldine, Sarah Khalaf, Ala-Eddin Al Moustafa.

  Due to the strong association between diabetes and cancer incidents, several anti-diabetic drugs, including metformin, have been examined for their anticancer activity. Metformin is a biguanide antihyperglycemic agent used as a first-line drug for type II diabetes mellitus. It exhibits anticancer activity by impacting different molecular pathways, such as AMP-inducible protein kinase (AMPK)-dependent and AMPK-independent pathways. Additionally, Metformin indirectly inhibits IGF-1R signaling, which is highly activated in breast malignancy. On the other hand, breast cancer is one of the major causes of cancer-related morbidity and mortality worldwide, where the human epidermal growth factor receptor-positive (HER2-positive) subtype is one of the most aggressive ones with a high rate of lymph node metastasis. In this review, we summarize the association between diabetes and human cancer, listing recent evidence of metformin's anticancer activity. A special focus is dedicated to HER2-positive breast cancer with regards to the interaction between HER2 and IGF-1R. Then, we discuss combination therapy strategies of metformin and other anti-diabetic drugs in HER2-positive breast cancer.

Keywords:  Breast cancer; Diabetes; HER2; HER2/IGF-1R interaction; Metformin

DOI:  https://doi.org/10.1016/j.biopha.2023.114676
J Pineal Res. 2023 Apr 11.

Melatonin protects against developmental PBDE-47 neurotoxicity by targeting the AMPK/mitophagy axis.

Lixin Dong, Qian Sun, Haixia Qiu, Kaichao Yang, Xiao Boya, Tao Xia, Aiguo Wang, Hui Gao, Shun Zhang.

  The neurotoxicity of 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47) is closely linked to mitochondrial abnormalities while mitophagy is vital for mitochondrial homeostasis. However, whether PBDE-47 disrupts mitophagy contributing to impaired neurodevelopment remain elusive. Here, this study showed that neonatal PBDE-47 exposure caused learning and memory deficits in adult rats, accompanied with striatal mitochondrial abnormalities, neuronal apoptosis and the resultant neuronal loss. Mechanistically, PBDE-47 suppressed PINK1/Parkin-mediated mitophagy induction and degradation, inducing mitophagosome accumulation and mitochondrial dysfunction in vivo and in vitro. Additionally, stimulation of mitophagy by adenovirus-mediated Parkin or Autophagy-related protein 7 (Atg7) overexpression aggravated PBDE-47-induced mitophagosome accumulation, mitochondrial dysfunction, neuronal apoptosis and death. Conversely, suppression of mitophagy by the siRNA knockdown of Atg7 rescued PBDE-47-induced detrimental consequences. Importantly, melatonin, a hormone secreted rhythmically by the pineal, improved PBDE-47-caused neurotoxicity via preventing neuronal apoptosis and loss by restoring mitophagic activity and mitochondrial function. These neuroprotective effects of melatonin depended on activation of the AMP-activated protein kinase (AMPK)/unc-51 like autophagy activating kinase 1 (ULK1) signaling. Collectively, these data indicate that PBDE-47 impairs mitophagy to perturb mitochondrial homeostasis, thus triggering apoptosis, leading to neuronal loss and consequent neurobehavioral deficits. Manipulation of the AMPK-mitophagy axis via melatonin could be a novel therapeutic strategy against developmental PBDE-47 neurotoxicity. This article is protected by copyright. All rights reserved.

Keywords:  2,2’,4,4’-tetrabromodiphenyl ether; AMPK/ULK1; Melatonin; Mitophagy; PINK1/Parkin

DOI:  https://doi.org/10.1111/jpi.12871
J Cell Physiol. 2023 Apr 13.

Lactobacillus plantarum postbiotics trigger AMPK-dependent autophagy to suppress Salmonella intracellular infection and NLRP3 inflammasome activation.

Yanping Wu, Aixin Hu, Xin Shu, Wenxia Huang, Ruiqiang Zhang, Yinglei Xu, Caimei Yang.

  We previously found that Lactobacillus plantarum (LP)-derived postbiotics protected animals against Salmonella infection, but the molecular mechanism remains obscure. This study clarified the mechanisms from the perspective of autophagy. Intestinal porcine epithelial cells (IPEC-J2) were pretreated with LP-derived postbiotics (the culture supernatant, LPC; or heat-killed bacteria, LPB), and then challenged with Salmonella enterica Typhimurium (ST). Results showed that LP postbiotics markedly triggered autophagy under ST infection, as indicated by the increased LC3 and Beclin1 and the decreased p62 levels. Meanwhile, LP postbiotics (particularly LPC) exhibited a strong capacity of inhibiting ST adhesion, invasion and replication. Pretreatment with the autophagy inhibitor 3-methyladenine (3-MA) led to a significant decrease of autophagy and the aggravated infection, indicating the importance of autophagy in LP postbiotics-mediated Salmonella elimination. LP postbiotics (especially LPB) significantly suppressed ST-induced inflammation by modulating inflammatory cytokines (the increased interleukin (IL)-4 and IL-10, and decreased tumor necrosis factor-α (TNF), IL-1β, IL-6 and IL-18). Furthermore, LP postbiotics inhibited NOD-like receptor protein 3 (NLRP3) inflammasome activation, as evidenced by the decreased levels of NLRP3, Caspase-1 and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC). Deficits in autophagy resulted in an increase of inflammatory response and inflammasome activation. Finally, we found that both LPC and LPB triggered AMP-activated protein kinase (AMPK) signaling pathway to induce autophagy, and this was further confirmed by AMPK RNA interference. The intracellular infection and NLRP3 inflammasome were aggravated after AMPK knockdown. In summary, LP postbiotics trigger AMPK-mediated autophagy to suppress Salmonella intracellular infection and NLRP3 inflammasome in IPEC-J2 cells. Our findings highlight the effectiveness of postbiotics, and provide a new strategy for preventing Salmonella infection.

Keywords:  AMPK; Lactobacillus plantarum; NLRP3 inflammasome; Salmonella infection; autophagy; postbiotic

DOI:  https://doi.org/10.1002/jcp.31016
Phytomedicine. 2023 Mar 31. pii: S0944-7113(23)00159-9. [Epub ahead of print]114 154798

Neferine ameliorates nonalcoholic steatohepatitis through regulating AMPK pathway.

Ming-Yue Wang, Shao-Shi Zhang, Meng-Fei An, Yue-Fei Xia, Mao-Si Fan, Ze-Rui Sun, Li-Juan Zhang, Yun-Li Zhao, Jun Sheng, Xuan-Jun Wang.

   BACKGROUND: Nonalcoholic fatty liver disease (NAFLD), peculiarly nonalcoholic steatohepatitis (NASH), has become the main cause of liver transplantation and liver-related death. However, the US Food and Drug Administration has not approved a specific medication for treating NASH. Neferine (NEF), a natural bisbenzylisoquinoline alkaloid separated from the traditional Chinese medicine Nelumbinis plumula, has a variety of pharmacological properties, especially on metabolic diseases. Nevertheless, the anti-NASH effect and mechanisms of NEF remain unclear.
PURPOSE: This study aimed to investigate the amelioration of NEF on NASH and the potential mechanisms.
STUDY DESIGN: HepG2 cells, hepatic stellate cells (HSCs) and high-fat diet (HFD)+carbon tetrachloride (CCl4) induced C57BL/6 mice were used to observe the effect of NEF against NASH and investigate the engaged mechanism.
METHODS: HSCs and HepG2 cells stimulated by oleic acid (OA) were treated with NEF. C57BL/6 mice were fed with HFD+CCl4 to induce NASH mouse model and treated with or without NEF (5 mg/kg or 10 mg/kg, once daily, i.p) for 4 weeks.
RESULTS: NEF significantly attenuated the accumulation of lipid droplets, intracellular triglyceride (TG) levels and hepatocytes apoptosis in OA-exposed HepG2 cells. NEF not only enhanced the AMPK and ACC phosphorylation in OA-stimulated HepG2 cells, but also reduced inflammatory response and fibrosis in lipopolysaccharide (LPS)-stimulated HepG2 and in LX-2, respectively. In HFD+CCl4-induced NASH mice, pathological staining confirmed NEF treatment mitigated hepatic lipid deposition, inflammatory cell infiltration as well as hepatic fibrosis. Furthermore, the liver weight, serum and hepatic TG and total cholesterol (TC) and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were decreased compared with the model group. HFD+CCl4 also induced the upregulation of specific proteins and genes associated to inflammation (ILs, TNF-α, NLRP3, ASC, CCL2 and CXCL10) and hepatic fibrosis (collagens, α-SMA, TGF-β and TIPM1), which were also suppressed by NEF treatment.
CONCLUSION: Our results demonstrated that NEF played a protective role in hepatic steatosis via the regulation of AMPK pathways, which may serve as an attractive candidate for a potential novel strategy on prevention and treatment of NASH.

Keywords:  Fibrosis; HepG2 cells; Inflammation; Lipid accumulation; NASH; NEF

DOI:  https://doi.org/10.1016/j.phymed.2023.154798
Cell Prolif. 2023 Apr 11. e13476

Constitutively activated AMPKα1 protects against skeletal aging in mice by promoting bone-derived IGF-1 secretion.

Yiqi Yang, Kai Yuan, Yihao Liu, Qishan Wang, Yixuan Lin, Shengbing Yang, Kai Huang, Tianyou Kan, Yuxin Zhang, Mingming Xu, Zhifeng Yu, Qiming Fan, Yugang Wang, Hanjun Li, Tingting Tang.

Senile osteoporosis is characterized by age-related bone loss and bone microarchitecture deterioration. However, little is known to date about the mechanism that maintains bone homeostasis during aging. In this study, we identify adenosine monophosphate-activated protein kinase alpha 1 (AMPKα1) as a critical factor regulating the senescence and lineage commitment of mesenchymal stem cells (MSCs). A phospho-mutant mouse model shows that constitutive AMPKα1 activation prevents age-related bone loss and promoted MSC osteogenic commitment with increased bone-derived insulin-like growth factor 1 (IGF-1) secretion. Mechanistically, upregulation of IGF-1 signalling by AMPKα1 depends on cAMP-response element binding protein (CREB)-mediated transcriptional regulation. Furthermore, the essential role of the AMPKα1/IGF-1/CREB axis in promoting aged MSC osteogenic potential is confirmed using three-dimensional (3D) culture systems. Taken together, these results can provide mechanistic insight into the protective effect of AMPKα1 against skeletal aging by promoting bone-derived IGF-1 secretion.

DOI: https://doi.org/10.1111/cpr.13476