bims-amsmem 2022-08-07 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2022–08–07
nineteen papers selected by
Dipsikha Biswas, Københavns Universitet

DHHC17 Is a New Regulator of AMPK Signaling.
In Silico and In Vitro Approach to Assess Direct Allosteric AMPK Activators from Nature.
Enhancement of BCAT2-Mediated Valine Catabolism Stimulates β-Casein Synthesis via the AMPK-mTOR Signaling Axis in Bovine Mammary Epithelial Cells.
Resveratrol Synergistically Promotes BMP9-Induced Osteogenic Differentiation of Mesenchymal Stem Cells.
LKB1: An emerging therapeutic target for cardiovascular diseases.
Decreased expression of GRIM-19 induces autophagy through the AMPK/ULK1 signaling pathway during adenomyosis.
Reducing VEGFB accelerates NAFLD and insulin resistance in mice via inhibiting AMPK signaling pathway.
Hypolipogenic effects of Icariside E4 via phosphorylation of AMPK and inhibition of MID1IP1 in HepG2 cells.
AMPK and NRF2: Interactive players in the same team for cellular homeostasis?
Ellagic Acid Alters Muscle Fiber-Type Composition and Promotes Mitochondrial Biogenesis through the AMPK Signaling Pathway in Healthy Pigs.
Empagliflozin inhibits macrophage inflammation through AMPK signaling pathway and plays an anti-atherosclerosis role.
Francisella tularensis Exploits AMPK Activation to Harvest Host-Derived Nutrients Liberated from Host Lipolysis.
Vitamin C Sensitizes Pancreatic Cancer Cells to Erastin-Induced Ferroptosis by Activating the AMPK/Nrf2/HMOX1 Pathway.
Penta-O-Galloyl-β-D-Glucose in Pistacia integerrima Targets AMPK-ULK1 and ERK/STAT3 Signaling Axes to Induce ROS-Independent Autophagic Cell Death in Human Lung Cancer Cells.
Aβ42 oligomers trigger synaptic loss through CAMKK2-AMPK-dependent effectors coordinating mitochondrial fission and mitophagy.
Berberine Attenuates IL-1β-Induced Damage of Nucleus Pulposus Cells via Activating the AMPK/mTOR/Ulk1 Pathway.
Hypothalamus-Muscle Parallel Induction of Metabolic Pathways Following Physical Exercise.
Diet-induced obesity impairs spermatogenesis: the critical role of NLRP3 in Sertoli cells.
Linagliptin in Combination With Metformin Ameliorates Diabetic Osteoporosis Through Modulating BMP-2 and Sclerostin in the High-Fat Diet Fed C57BL/6 Mice.

Mol Cell Biol. 2022 Aug 01. e0013122

DHHC17 Is a New Regulator of AMPK Signaling.

Yingmin Sun, Keyong Du.

  The association of AMP-activated protein kinase (AMPK) with membranes plays a critical role in the regulation of AMPK activation and function. Protein lipid modification, including palmitoylation, myristoylation, and farnesyation, constitutes a crucial mechanism in the regulation of protein dynamic interactions with membranes. Among the three subunits of the AMPK heterotrimeric complex, the structural subunit AMPKβ is myristoylated and the catalytic subunit AMPKα is palmitoylated. Here, we report the characterization of AMPKα palmitoylation. We found that AMKPα was palmitoylated at Cys209 and Cys543, and this was required for AMPK activation and subcellular membrane compartmentalization. To understand the regulation of AMPKα palmitoylation, we have identified DHHC17 as a candidate palmitoyltransferase for AMPKα and found that DHHC17, by palmitoylating AMPKα, modulated AMPK membrane association and activation in response to energy stress. To determine the role of DHHC17 in cell function, we generated DHHC17 liver-specific knockout mice and found that inactivation of DHHC17 in the mouse liver impaired AMPK activation and hepatic autophagy and caused a type 2 diabetes-like syndrome. Overall, our studies demonstrate that AMPKα palmitoylation plays a critical role in AMPK activation and that DHHC17, through its modulation of AMPK signaling, constitutes a new regulator of hepatic metabolism.

Keywords:  AMPK; DHHC protein; hyperglycemia; lipid metabolism; liver; palmitoylation; palmitoyltransferase; signal transduction

DOI:  https://doi.org/10.1128/mcb.00131-22
Planta Med. 2022 Aug;88(9-10): 794-804

In Silico and In Vitro Approach to Assess Direct Allosteric AMPK Activators from Nature.

Benjamin Kirchweger, Andreas Wasilewicz, Katrin Fischhuber, Ammar Tahir, Ya Chen, Elke H Heiss, Thierry Langer, Johannes Kirchmair, Judith M Rollinger.

The 5'-adenosine monophosphate-activated protein kinase (AMPK) is an important metabolic regulator. Its allosteric drug and metabolite binding (ADaM) site was identified as an attractive target for direct AMPK activation and holds promise as a novel mechanism for the treatment of metabolic diseases. With the exception of lusianthridin and salicylic acid, no natural product (NP) is reported so far to directly target the ADaM site. For the streamlined assessment of direct AMPK activators from the pool of NPs, an integrated workflow using in silico and in vitro methods was applied. Virtual screening combining a 3D shape-based approach and docking identified 21 NPs and NP-like molecules that could potentially activate AMPK. The compounds were purchased and tested in an in vitro AMPK α 1 β 1 γ 1 kinase assay. Two NP-like virtual hits were identified, which, at 30 µM concentration, caused a 1.65-fold (± 0.24) and a 1.58-fold (± 0.17) activation of AMPK, respectively. Intriguingly, using two different evaluation methods, we could not confirm the bioactivity of the supposed AMPK activator lusianthridin, which rebuts earlier reports.

DOI: https://doi.org/10.1055/a-1797-3030
J Agric Food Chem. 2022 Aug 02.

Enhancement of BCAT2-Mediated Valine Catabolism Stimulates β-Casein Synthesis via the AMPK-mTOR Signaling Axis in Bovine Mammary Epithelial Cells.

Xinling Wang, Jie Xu, Hanfang Zeng, Zhaoyu Han.

  Valine, a kind of branched-chain amino acid, plays a regulatory role beyond that of a building block in milk protein synthesis. However, the underlying molecular mechanism through which valine stimulates β-casein synthesis has not been clarified. Therefore, our study aimed to evaluate the effect of valine on β-casein synthesis and shed light into the molecular mechanism using an in vitro model. Results showed that valine supplementation significantly increased β-casein synthesis in bovine mammary epithelial cells (BMECs). Meanwhile, the supplementation of valine resulted in high levels of branched-chain aminotransferase transaminase 2 (BCAT2), TCA-cycle intermediate metabolites, and ATP, AMP-activated protein kinase (AMPK) inhibition, and mammalian target of rapamycin (mTOR) activation. Furthermore, the inhibition of BCAT2 decreased the β-casein synthesis and downregulated the AMPK-mTOR pathway, with similar results observed for AMPK activation. Together, the present data indicate that valine promotes the synthesis of β-casein by affecting the AMPK-mTOR signaling axis and that BCAT2-mediated valine catabolism is the key target.

Keywords:  bovine mammary epithelial cell; branched-chain aminotransferase transaminase 2; valine; β-casein

DOI:  https://doi.org/10.1021/acs.jafc.2c03629
Stem Cells Int. 2022 ;2022 8124085

Resveratrol Synergistically Promotes BMP9-Induced Osteogenic Differentiation of Mesenchymal Stem Cells.

Yonghui Wang, Chao Xia, Yang Chen, Tianyuan Jiang, Yan Hu, Yanhong Gao.

Background: Mesenchymal stem cells (MSCs) differentiate into osteocytes, adipocytes, and chondrocytes. Resveratrol and bone morphogenetic protein 9 (BMP9) are known osteogenic induction factors of MSCs, but the effect of both resveratrol and BMP9 on osteogenesis is unknown. Herein, we explored whether resveratrol cooperates with BMP9 to improve osteogenic induction.
Methods: The osteogenic induction of resveratrol and BMP9 on C3H10T1/2 cells was evaluated by detecting the staining and activity of the early osteogenic marker alkaline phosphatase (ALP). In addition, the late osteogenic effect was measured by the mRNA and protein levels of osteogenic markers, such as osteopontin (OPN) and osteocalcin (OCN). To assess the bone formation function of resveratrol plus BMP9 in vivo, we transplanted BMP9-infected C3H10T1/2 cells into nude mice followed by intragastric injection of resveratrol. Western blot (WB) analysis was utilized to elucidate the mechanism of resveratrol plus BMP9.
Results: Resveratrol not only enhanced osteogenic induction alone but also improved BMP9-induced ALP at 3, 5, and 7 d postinduction. Both the early osteogenic markers (ALP, Runx2, and SP7) and the late osteogenic markers (OPN and OCN) were significantly increased when resveratrol was combined with BMP9. The fetal limb explant culture further verified these results. The in vivo bone formation experiment, which involved transplanting BMP9-overexpressing C3H10T1/2 cells into nude mice, also confirmed that resveratrol synergistically enhanced the BMP9-induced bone formation function. Resveratrol phosphorylated adenosine monophosphate- (AMP-) activated protein kinase (AMPK) and stimulated autophagy, but these effects were abolished by inhibiting AMPK and Beclin1 using an inhibitor or siRNA.
Conclusions: Resveratrol combined with BMP9 significantly improves the osteogenic induction of C3H10T1/2 cells by activating AMPK and autophagy.

DOI: https://doi.org/10.1155/2022/8124085
Life Sci. 2022 Jul 27. pii: S0024-3205(22)00544-6. [Epub ahead of print]306 120844

LKB1: An emerging therapeutic target for cardiovascular diseases.

Ali Molaei, Emad Molaei, Hamidreza Sadeghnia, A Wallace Hayes, Gholamreza Karimi.

  Cardiovascular diseases (CVDs) are currently the most common cause of morbidity and mortality worldwide. Experimental studies suggest that liver kinase B1 (LKB1) plays an important role in the heart. Several studies have shown that cardiomyocyte-specific LKB1 deletion leads to hypertrophic cardiomyopathy, left ventricular contractile dysfunction, and an increased risk of atrial fibrillation. In addition, the cardioprotective effects of several medicines and natural compounds, including metformin, empagliflozin, bexarotene, and resveratrol, have been reported to be associated with LKB1 activity. LKB1 limits the size of the damaged myocardial area by modifying cellular metabolism, enhancing the antioxidant system, suppressing hypertrophic signals, and inducing mild autophagy, which are all primarily mediated by the AMP-activated protein kinase (AMPK) energy sensor. LKB1 also improves myocardial efficiency by modulating the function of contractile proteins, regulating the expression of electrical channels, and increasing vascular dilatation. Considering these properties, stimulation of LKB1 signaling offers a promising approach in the prevention and treatment of heart diseases.

Keywords:  AMPK; Cardiac remodeling; Cardiovascular diseases; Cellular metabolism; LKB1

DOI:  https://doi.org/10.1016/j.lfs.2022.120844
Biol Reprod. 2022 Jul 31. pii: ioac151. [Epub ahead of print]

Decreased expression of GRIM-19 induces autophagy through the AMPK/ULK1 signaling pathway during adenomyosis.

YuFei Huang, Yue Zhao, HaoRan Liu, Yang Yang, LaiYang Cheng, XiaoHui Deng, Lan Chao.

  The processes underlying adenomyosis are similar to those of tumor metastasis, and it is defined as progressive invasion by the endometrium and the subsequent creation of ectopic lesions. GRIM-19 regulates cell death via the mitochondrial respiratory chain. Stress following oxygen deprivation can induce tumor cell autophagy, leading to cell invasion and migration. Here, we revealed that GRIM-19 negatively regulates autophagy, and, at least in adenomyosis, decreased expression of GRIM-19 is accompanied by an increased level of autophagy and 5'-adenosine monophosphate-activated protein kinase-Unc-51 like autophagy activating kinase 1 (AMPK-ULK1) activation. Upregulation of GRIM-19 expression in human primary endometrial cells and ISHIKAWA cells inhibits autophagy via the AMPK-ULK1 pathway and helps control cell invasion and migration. In addition, we also identified increased expression of AMPK and ULK1, and higher levels of autophagy in the uterine tissues of GRIM-19+/- mice. Importantly, the function of the GRIM-19-AMPK-ULK1 axis in regulating autophagy in adenomyosis is similar to that of tumor tissues, which may help elucidate the regulation of adenomyosis tumor-like behavior, and is expected to help identify novel targets for the diagnosis and treatment of adenomyosis.

Keywords:  AMPK; Adenomyosis; Autophagy; GRIM-19; GRIM-19+/− mice; ULK1

DOI:  https://doi.org/10.1093/biolre/ioac151
J Transl Med. 2022 Jul 30. 20(1): 341

Reducing VEGFB accelerates NAFLD and insulin resistance in mice via inhibiting AMPK signaling pathway.

Rongrong Li, Yuqi Li, Xueling Yang, Yaorui Hu, Haining Yu, Yana Li.

   OBJECTIVE: Vascular endothelial growth factor B (VEGFB) was regarded to improve lipid metabolism and reduce obesity-related hyperlipidemia. Whether VEGFB participates in lipid metabolism in nonalcoholic fatty liver disease (NAFLD) has not been clear yet. This study investigated the involvement of VEGFB in lipid metabolism and insulin resistance via the AMPK signaling pathway in NAFLD.
METHODS: We constructed the animal and cell model of NAFLD after VEGFB gene knockout to detect liver damage and metabolism in NAFLD. Bioinformatics analysis of VEGFB and the AMPK signaling pathway relative genes to verify the differential proteins. And mRNA levels of NAFLD fatty acid metabolism-related genes were detected.
RESULTS: After the systemic VEGFB knockout mice were fed with high fat, the body fat, serum lipoprotein, NAFLD score, and insulin resistance were increased. Animal and cell experiments showed that the expression levels of phosphorylated proteins of CaMKK2 and AMPK decreased, the expression of proteins related to AMPK/ACC/CPT1 signaling pathway decreased, and the target genes CPT1α and Lcad decreased accordingly, reducing fatty acid oxidation in hepatocyte mitochondria; The expression of AMPK/SREBP1/Scd1 signaling pathway relative proteins increased, ACC1 and FAS increased correspondingly, which increased lipid synthesis in the endoplasmic reticulum.
CONCLUSION: VEGFB can participate in lipid metabolism and insulin resistance of NAFLD through the AMPK signaling pathway.

Keywords:  AMPK/ACC; AMPK/SREBP1; Lipid metabolism; NAFLD; VEGFB

DOI:  https://doi.org/10.1186/s12967-022-03540-2
Phytother Res. 2022 Aug 02.

Hypolipogenic effects of Icariside E4 via phosphorylation of AMPK and inhibition of MID1IP1 in HepG2 cells.

Jin Young Suh, Hyo-Jung Lee, Deok Yong Sim, Ji Eon Park, Chi-Hoon Ahn, Su-Yeon Park, Nari Shin, Bonglee Kim, Bum Sang Shim, Sung-Hoon Kim.

  Though icariside E4 (IE4) is known to have anti-noceptive, anti-oxidant, anti-Alzheimer and anti-inflammatory effects, there was no evidence on the effect of IE4 on lipid metabolism so far. Hence, the hypolipogenic mechanism of IE4 was investigated in HepG2 hepatocellular carcinoma cells (HCCs) in association with MID1 Interacting Protein 1(MID1IP1) and AMPK signaling. Here, IE4 did not show any toxicity in HepG2 cells, but reduced lipid accumulation in HepG2 cells by Oil Red O staining. MID1IP1 depletion decreased the expression of SREBP-1c and fatty acid synthase (FASN) and induced phosphorylation of ACC in HepG2 cells. Indeed, IE4 activated phosphorylation of AMPK and ACC and inhibited the expression of MID1IP1 in HepG2 cells. Furthermore, IE4 suppressed the expression of SREBP-1c, liver X receptor-α (LXR), and FASN for de novo lipogenesis in HepG2 cells. Interestingly, AMPK inhibitor compound C reversed the ability of IE4 to reduce MID1IP1, SREBP-1c, and FASN and activate phosphorylation of AMPK/ACC in HepG2 cells, indicating the important role of AMPK/ACC signaling in IE4-induced hypolipogenic effect. Taken together, these findings suggest that IE4 has hypolipogenic potential in HepG2 cells via activation of AMPK and inhibition of MID1IP1 as a potent candidate for treatment of fatty liver disease.

Keywords:  AMPK; HepG2 cells; Icariside E4; MID1IP1; compound C; lipogenesis

DOI:  https://doi.org/10.1002/ptr.7584
Free Radic Biol Med. 2022 Jul 30. pii: S0891-5849(22)00497-X. [Epub ahead of print]

AMPK and NRF2: Interactive players in the same team for cellular homeostasis?

Eleni Petsouki, Shara Natalia Sosa Cabrera, Elke H Heiss.

  NRF2 (Nuclear factor E2 p45-related factor 2) is a stress responsive transcription factor lending cells resilience against oxidative, xenobiotic, and also nutrient or proteotoxic insults. AMPK (AMP-activated kinase), considered as prime regulator of cellular energy homeostasis, not only tunes metabolism to provide the cell at any time with sufficient ATP or building blocks, but also controls redox balance and inflammation. Due to observed overlapping cellular responses upon AMPK or NRF2 activation and common stressors impinging on both AMPK and NRF2 signaling, it is plausible to assume that AMPK and NRF2 signaling may interdepend and cooperate to readjust cellular homeostasis. After a short introduction of the two players this narrative review paints the current picture on how AMPK and NRF2 signaling might interact on the molecular level, and highlights their possible crosstalk in selected examples of pathophysiology or bioactivity of drugs and phytochemicals.

Keywords:  AMPK; Metabolism; NRF2; ROS; Stress response

DOI:  https://doi.org/10.1016/j.freeradbiomed.2022.07.014
J Agric Food Chem. 2022 Aug 02.

Ellagic Acid Alters Muscle Fiber-Type Composition and Promotes Mitochondrial Biogenesis through the AMPK Signaling Pathway in Healthy Pigs.

Huawei Li, Xiaoling Chen, Daiwen Chen, Bing Yu, Jun He, Ping Zheng, Yuheng Luo, Hui Yan, Hong Chen, Zhiqing Huang.

  Ellagic acid (EA), because of its remarkable health-promoting ability, has aroused widespread interest in the fields of nutrition and medicine. However, no reports showed that EA regulates mitochondrial biogenesis as well as muscle fiber-type composition in pigs. Our study found that dietary 75 and 150 mg/kg EA obviously augmented the slow myosin heavy chain (MyHC) protein level, the number of slow-twitch muscle fibers, and the activity of malate dehydrogenase (MDH) in the longissimus thoracis (LT) muscle of growing-finishing pigs. In contrast, dietary 75 and 150 mg/kg EA decreased the fast MyHC level, the number of fast-twitch muscle fibers, and the activity of lactate dehydrogenase (LDH) in the LT muscle. In addition, our further study found that dietary 75 and 150 mg/kg EA promoted the mitochondrial DNA (mtDNA) content, the mRNA expressions of ATP synthase (ATP5G), mtDNA transcription factor A (TFAM), AMP-activated protein kinase α1 (AMPKα1), peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) and sirtuin 1 (Sirt1), and the level of phospho-LKB1 (P-LKB1), phospho-AMPK (P-AMPK), Sirt1, and PGC-1α in the LT muscle. In vitro, 5, 10, and 20 μmol/L EA treatment upregulated the level of slow MyHC, but only 10 μmol/L EA treatment decreased fast MyHC protein expression in porcine skeletal muscle satellite cells (PSCs). In addition, our data again found that 10 μmol/L EA treatment promoted the mtDNA content, the mRNA levels of ATP5G, mitochondrial transcription factor b1 (TFB1M), citrate synthase (Cs), AMPKα1, PGC-1α, and Sirt1, and the protein expressions of P-AMPK, P-LKB1, PGC-1α, and Sirt1 in PSCs. What is more, inhibition of the AMPK signaling pathway by AMPKα1 siRNA significantly eliminated the improvement of EA on muscle fiber-type composition as well as the mtDNA content in PSCs. In conclusion, EA altered muscle fiber-type composition and promoted mitochondrial biogenesis through the AMPK signaling pathway.

Keywords:  AMPK signaling pathway; ellagic acid; growing-finishing pigs; mitochondrial biogenesis; muscle fiber-type composition

DOI:  https://doi.org/10.1021/acs.jafc.2c04108
Int J Cardiol. 2022 Aug 02. pii: S0167-5273(22)01119-6. [Epub ahead of print]

Empagliflozin inhibits macrophage inflammation through AMPK signaling pathway and plays an anti-atherosclerosis role.

Jie Fu, Hualin Xu, Fuyun Wu, Qiang Tu, Xiao Dong, Huaqiang Xie, Zheng Cao.

   OBJECTIVE: In recent years, some authoritative clinical studies have found that SGLT2 inhibitor can reduce cardiovascular risk in patients with diabetes, which may imply that SGLT2 inhibitor can play a role beyond lowering blood glucose. In this study, we explored the effect of empagliflozin on vascular atherosclerosis after removing the effect of diabetes.
METHODS: The interaction between SGLT2 inhibitor and the AMPK(Adenosine 5'-monophosphate-activated protein kinase) signal pathway to attenuate atherosclerosis was studied in both spontaneously atherosclerotic mice in vivo and oxidized low-density lipoprotein(ox-LDL) induced macrophage inflammation model in vitro. In vivo experiment the aorta tree and aortic valve area were stained with oil red, and the level of inflammatory factors in the diseased tissue was evaluated by immunohistochemistry. Meanwhile, serum was collected to detect the levels of inflammatory factors. In vitro experiment, the RAW264.7 cell line was selected and ox-LDL was used to induce the release of proinflammatory factors, and different doses of empagliflozin were added. The phagocytosis of macrophages to ox-LDL density lipoprotein, and the expression of inflammatory factors at the protein and RNA levels were measured.
RESULTS: Empagliflozin reduced the area of atherosclerotic plaque and macrophage infiltration in atherosclerotic plaques, decreased the expression of inflammatory factors in local plaque tissues and serum of APOE-/- mice fed with high-fat diet. Empagliflozin can improve the protein expression level of p-AMPK affected by ox-LDL in cell and reduce the gene expression level of inflammatory factors and protein expression level of NF-κB, thus playing an anti-atherosclerosis role.
CONCLUSIONS: Empagliflozin improves energy metabolism and reduces the expression of inflammatory factors by activating AMPK. As empagliflozin inhibits atherosclerosis progression, it may be of use in prevention of cardiovascular diseases.

Keywords:  Atherosclerotic; Empagliflozin; Inflammation; Macrophage; p-AMPK

DOI:  https://doi.org/10.1016/j.ijcard.2022.07.048
Infect Immun. 2022 Aug 02. e0015522

Francisella tularensis Exploits AMPK Activation to Harvest Host-Derived Nutrients Liberated from Host Lipolysis.

Sedelia R Dominguez, Shannon Whiles, Kelly N Deobald, Thomas Kawula.

  Francisella tularensis is a zoonotic, facultative intracellular bacterial pathogen that replicates in a variety of cell types during infection. Following entry into the cell and phagosome escape, the bacterium replicates rapidly in the cytoplasm. F. tularensis intracellular growth depends on the availability of metabolizable essential nutrients to support replication. However, the mechanism by which metabolizable nutrients become available to the bacterium in the intracellular environment is not fully understood. We found that F. tularensis-infected cells had significantly smaller and fewer lipid droplets than uninfected cells. Inhibition of triacylglycerol degradation significantly reduced bacterial growth, whereas inhibition of triacylglycerol formation did not reduce bacterial growth, suggesting that triacylglycerols sequestered within lipid droplets are important nutrient sources for F. tularensis. We found that F. tularensis-infected cells had increased activation of lipolysis and the upstream regulatory protein AMP protein kinase (AMPK). These data suggest that F. tularensis exploits AMPK activation and lipid metabolism to use host-derived nutrients. Finally, we found that AMPK activation is correlated with an increased bacterial burden, which suggests that it is a host-mediated response to nutrient starvation that results from increased bacterial replication. Altogether, we conclude that F. tularensis exploits AMPK activation to access nutrients sequestered in lipid droplets, specifically glycerol and fatty acids, to undergo efficient bacterial replication and cause successful infection.

Keywords:  Francisella tularensis; carbon metabolism; host-pathogen interactions; infectious disease; nutritional immunity; zoonotic infections

DOI:  https://doi.org/10.1128/iai.00155-22
Oxid Med Cell Longev. 2022 ;2022 5361241

Vitamin C Sensitizes Pancreatic Cancer Cells to Erastin-Induced Ferroptosis by Activating the AMPK/Nrf2/HMOX1 Pathway.

Yawen Liu, Pu Huang, Zheng Li, Chunhui Xu, Huizhi Wang, Baoqing Jia, Aihua Gong, Min Xu.

Ferroptosis is a type of regulated cell death that displays a promising therapeutic pathway for drug-resistant tumor cells. However, some pancreatic cancer (PC) cells are less sensitive to erastin-induced ferroptosis, and normal pancreatic cells are susceptible to this newly discovered cell death. Therefore, there is an urgent need to find drugs to enhance the sensitivity of these PC cells to erastin while limiting side effects. Here, we found that the oxidized form of vitamin C-dehydroascorbic acid (DHA) can be transported into PC cells expressing high levels of GLUT1, resulting in ferroptosis. Moreover, pharmacological vitamin C combined with erastin can synergistically induce ferroptosis of PC cells involving glutathione (GSH) reduction and ferrous iron accumulation while inhibiting the cytotoxicity of normal cells. Mechanistically, as a direct system Xc- inhibitor, erastin can directly suppress the synthesis of GSH, and the recycling of vitamin C and DHA is performed through GSH consumption, which is denoted as the classical mode. Furthermore, oxidative stress induced by erastin and vitamin C could enhance the expression of HMOX1 via the AMP-activated protein kinase (AMPK)/nuclear factor erythroid 2-related factor 2 (NRF2) pathway to increase the labile iron level, which is named the nonclassical mode. In vivo experiments showed that erastin and vitamin C can significantly slow tumor growth in PC xenografts. In summary, the combination of erastin and vitamin C exerts a synergistic effect of classical and nonclassical modes to induce ferroptosis in PC cells, which may provide a promising therapeutic strategy for PC.

DOI: https://doi.org/10.1155/2022/5361241
Front Pharmacol. 2022 ;13 889335

Penta-O-Galloyl-β-D-Glucose in Pistacia integerrima Targets AMPK-ULK1 and ERK/STAT3 Signaling Axes to Induce ROS-Independent Autophagic Cell Death in Human Lung Cancer Cells.

Acharya Balkrishna, Vallabh Prakash Mulay, Sudeep Verma, Jyotish Srivastava, Savita Lochab, Anurag Varshney.

  Natural molecules have promising perspectives as adjuvants to chemotherapies against cancer. Pistacia chinensis subsp. Integerrima (hereafter, Pistacia integerrima) traditionally known for medicinal values in respiratory disorders was tested for anti-lung cancer properties. The extract prepared from Pistacia integerrima (PI) selectively impaired the viability of lung cancer cells, A549 and NCI-H460, compared to non-cancer cells. At non-lethal concentrations, PI mitigated colony-forming, spheroid formations and metastatic properties of lung cancer cells. As a step toward identifying the phytomolecule that is imparting the anti-lung cancer properties in PI, we subjected the extract to extensive characterization through UPLC/QToF-MS and further validated the findings with UHPLC. The gallotannin, penta-O-galloyl-β-D-glucose (PGG), among others, was identified through UPLC/QToF-MS. PGG exhibits potential chemopreventive effects against various cancer types. However, a defined mechanism of action of PGG in restricting lung cancer progression is still unexplored. Bioactivity-guided column fractionations enabled the determination of PGG as the major phytochemical that governed PI-mediated AMPK-ULK1-dependent autophagy and apoptosis, albeit independent of intracellular ROS activation. Interestingly, the autophagy flux when inhibited restored the cell viability even in the presence of PI. The study further delineated that PI and PGG activated ERK and inhibited STAT3 to trigger apoptosis through caspase-3 and PARP 1 pathways. Collectively, the finding demonstrates that plant extract, PGG, in the PI extract effectively combats lung cancer progression through autophagic cell death by altering ERK/AMPK-ULK1/STAT3 signaling axes. The study proposes PGG as a potential AMPK activator and STAT3 inhibitor that can be exploited further in developing adjuvant chemotherapeutics against lung cancer.

Keywords:  AMPK activator; Pistacia integerrima; STAT3 inhibitor; UPLC/Q-TOF-MS; autophagic cell death; lung cancer; natural molecules; penta-O-galloyl-β-D-glucose

DOI:  https://doi.org/10.3389/fphar.2022.889335
Nat Commun. 2022 Aug 01. 13(1): 4444

Aβ42 oligomers trigger synaptic loss through CAMKK2-AMPK-dependent effectors coordinating mitochondrial fission and mitophagy.

Annie Lee, Chandana Kondapalli, Daniel M Virga, Tommy L Lewis, So Yeon Koo, Archana Ashok, Georges Mairet-Coello, Sebastien Herzig, Marc Foretz, Benoit Viollet, Reuben Shaw, Andrew Sproul, Franck Polleux.

During the early stages of Alzheimer's disease (AD) in both mouse models and human patients, soluble forms of Amyloid-β 1-42 oligomers (Aβ42o) trigger loss of excitatory synapses (synaptotoxicity) in cortical and hippocampal pyramidal neurons (PNs) prior to the formation of insoluble amyloid plaques. In a transgenic AD mouse model, we observed a spatially restricted structural remodeling of mitochondria in the apical tufts of CA1 PNs dendrites corresponding to the dendritic domain where the earliest synaptic loss is detected in vivo. We also observed AMPK over-activation as well as increased fragmentation and loss of mitochondrial biomass in Ngn2-induced neurons derived from a new APPSwe/Swe knockin human ES cell line. We demonstrate that Aβ42o-dependent over-activation of the CAMKK2-AMPK kinase dyad mediates synaptic loss through coordinated phosphorylation of MFF-dependent mitochondrial fission and ULK2-dependent mitophagy. Our results uncover a unifying stress-response pathway causally linking Aβ42o-dependent structural remodeling of dendritic mitochondria to synaptic loss.

DOI: https://doi.org/10.1038/s41467-022-32130-5
Biomed Res Int. 2022 ;2022 6133629

Berberine Attenuates IL-1β-Induced Damage of Nucleus Pulposus Cells via Activating the AMPK/mTOR/Ulk1 Pathway.

Liaoyuan Huang, Jianming Chen, Danhai Wu, Kan Wang, Weigang Lou, Jianmin Wu.

Intervertebral disc degeneration (IDD) is a chronic progressive condition mainly caused by excessive inflammatory cytokines. Berberine (BBR) exerts anti-inflammatory effect on diseases and protective effect against IDD. However, the mechanism is not uncertain. This study is aimed at investigating the molecular mechanism of BBR on IDD. Nucleus pulposus (NP) cells were treated with BBR at different concentrations. The IDD rat model was established by acupuncture. The effect of BBR on interleukin- (IL-) 1β-induced cell proliferation was measured by CCK-8 assay and BrdU staining. The role of BBR in IL-1β-induced apoptosis, autophagy repression, and extracellular matrix (ECM) degradation was measured by Annexin/PI staining, immunofluorescence, and immunoblot. The effect of BBR on IDD was investigated in rat. Our findings showed that BBR restored cell growth and attenuated apoptosis in IL-1β-induced NP cells. BBR also prevented the IL-1β-induced ECM degradation through regulating ECM-related enzymes and factors. Additionally, BBR significantly activated autophagy repressed by IL-1β. Autophagy stimulated by BBR was diminished by the inhibition of the AMPK/mTOR/Ulk1 signaling pathway. In vivo study also showed BBR attenuated intervertebral disc degeneration. BBR could attenuate NP cells apoptosis and ECM degradation induced by IL-1β through autophagy by the AMPK/mTOR/Ulk1 pathway. This study suggests BBR might function as an AMPK activator to alleviate IDD progression.

DOI: https://doi.org/10.1155/2022/6133629
Front Neurosci. 2022 ;16 897005

Hypothalamus-Muscle Parallel Induction of Metabolic Pathways Following Physical Exercise.

Almog Katz, Meital Gonen, Yael Shahar, Asael Roichman, Batia Lerrer, Haim Yosef Cohen.

  The modern lifestyle requires less physical activity and skills during our daily routine, leading to multiple pathologies related to physical disabilities and energy accessibility. Thus, exploring the mechanisms underlying the metabolic regulation of exercise is crucial. Here, we characterized the effect of forced and voluntary endurance exercises on three key metabolic signaling pathways, sirtuins, AMPK, and mTOR, across several metabolic tissues in mice: brain, muscles, and liver. Both voluntary and forced exercises induced AMPK with higher intensity in the first. The comparison between those metabolic tissues revealed that the hypothalamus and the hippocampus, two brain parts, showed different metabolic signaling activities. Strikingly, despite the major differences in the physiology of muscles and hypothalamic tissues, the hypothalamus replicates the metabolic response of the muscle in response to physical exercise. Specifically, muscles and hypothalamic tissues showed an increase and a decrease in AMPK and mTOR signaling, respectively. Overall, this study reveals new insight into the relation between the hypothalamus and muscles, which enhances the coordination within the muscle-brain axis and potentially improves the systemic response to physical activity performance and delaying health inactivity disorders.

Keywords:  exercise; hippocampus; hypothalamus; metabolic pathways; muscle

DOI:  https://doi.org/10.3389/fnins.2022.897005
Inflamm Regen. 2022 Aug 02. 42(1): 24

Diet-induced obesity impairs spermatogenesis: the critical role of NLRP3 in Sertoli cells.

Yang Mu, Tai-Lang Yin, Yan Zhang, Jing Yang, Yan-Ting Wu.

   BACKGROUND: Accumulating evidence indicates a key role of Sertoli cell (SC) malfunction in spermatogenesis impairment induced by obesity. Nucleotide-binding oligomerization domain-like receptor with a pyrin domain 3 (NLRP3) is expressed in SCs, but the role of NLRP3 in the pathological process of obesity-induced male infertility remains unclear.
METHODS: NLRP3-deficient mice were fed a high-fat diet for 24 weeks to establish obesity-related spermatogenesis impairment. In another set of experiments, a lentiviral vector containing a microRNA (miR)-451 inhibitor was injected into AMP-activated protein kinase α (AMPKα)-deficient mouse seminiferous tubules. Human testis samples were obtained by testicular puncture from men with obstructive azoospermia whose samples exhibited histologically normal spermatogenesis. Isolated human SCs were treated with palmitic acid (PA) to mimic obesity model in vitro.
RESULTS: Increased NLRP3 expression was observed in the testes of obese rodents. NLRP3 was also upregulated in PA-treated human SCs. NLRP3 deficiency attenuated obesity-related male infertility. SC-derived NLRP3 promoted interleukin-1β (IL-1β) secretion to impair testosterone synthesis and sperm performance and increased matrix metalloproteinase-8 (MMP-8) expression to degrade occludin via activation of nuclear factor-kappa B (NF-κB). Increased miR-451 caused by obesity, decreased AMPKα expression and sequentially increased NADPH oxidase activity were responsible for the activation of NLRP3. miR-451 inhibition protected against obesity-related male infertility, and these protective effects were abolished by AMPKα deficiency in mice.
CONCLUSIONS: NLRP3 promoted obesity-related spermatogenesis impairment. Increased miR-451 expression, impaired AMPKα pathway and the subsequent ROS production were responsible for NLRP3 activation. Our study provides new insight into the mechanisms underlying obesity-associated male infertility.

Keywords:  AMPKα; MicroRNA; NLRP3, Obesity; Sertoli cells

DOI:  https://doi.org/10.1186/s41232-022-00203-z
Front Endocrinol (Lausanne). 2022 ;13 944323

Linagliptin in Combination With Metformin Ameliorates Diabetic Osteoporosis Through Modulating BMP-2 and Sclerostin in the High-Fat Diet Fed C57BL/6 Mice.

Nikita Nirwan, Divya Vohora.

   Background: Diabetic osteoporosis is a poorly managed serious skeletal complication, characterized by high fracture risk, increased bone resorption, reduced bone formation, and disrupted bone architecture. There is a need to investigate drugs that can improve bone health along with managing glycemic control. DPP-4 inhibitors and metformin have proven benefits in improving bone health. Here, we investigated the effects of linagliptin, a DPP inhibitor, and metformin alone and in combination to treat diabetic osteoporosis in high-fat-fed mice.
Methods: C57BL/6 mice were kept on the high-fat diet (HFD) for 22 weeks to induce diabetic osteoporosis. Linagliptin (10mg/Kg), metformin (150mg/Kg), and their combination were orally administered to the diabetic mice from the 18th-22nd week. Femur and tibial bone microarchitecture together with bone mineral density (BMD) were evaluated using µCT and histopathological changes were assessed. Further, bone turnover biomarkers namely bone morphogenetic protein-2 (BMP-2), sclerostin, tartrate-resistant acid phosphatase (TRAP), osteocalcin, alkaline phosphatase (ALP), calcium, and pro-inflammatory cytokines were assessed. Additionally, metabolic parameters including body weight, fasting blood glucose (FBG), glucose & insulin tolerance, lipids profile, and leptin were measured.
Results: HFD feeding resulted in impaired bone microarchitecture, reduced BMD, distorted bone histology, and altered bone turnover biomarkers as indicated by the significant reduction in bone ALP, BMP-2, osteocalcin, and an increase in sclerostin, TRAP, and serum calcium. Interestingly, treatment with linagliptin and its combination with metformin significantly reverted the impaired bone architecture, BMD, and positively modulated bone turnover biomarkers, while metformin alone did not exhibit any significant improvement. Further, HFD induced diabetes and metabolic abnormalities (including an increase in body weight, FBG, impaired glucose and insulin tolerance, leptin, triglycerides, cholesterol), and pro-inflammatory cytokines (TNF-alpha and IL-1β) were successfully reversed by treatment with linagliptin, metformin, and their combination.
Conclusion: Linagliptin and its combination with metformin successfully ameliorated diabetic osteoporosis in HFD-fed mice possibly through modulation of BMP-2 and sclerostin. The study provides the first evidence for the possible use of linagliptin and metformin combination for managing diabetic osteoporosis.

Keywords:  DPP-4 inhibitors; bone architecture; diabetes; high fat diet (HFD); linagliptin; metformin; osteoporosis

DOI:  https://doi.org/10.3389/fendo.2022.944323