bims-amsmem 2023-06-11 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2023‒06‒11
seven papers selected by
Dipsikha Biswas, Københavns Universitet

Discovery of a natural small-molecule AMP-activated kinase activator that alleviates nonalcoholic steatohepatitis.
Sweroside alleviates hepatic steatosis in part by activating AMPK/mTOR-mediated autophagy in mice.
Patulin alleviates hepatic lipid accumulation by regulating lipogenesis and mitochondrial respiration.
Mitochondrial-Derived Peptide MOTS-c Ameliorates Spared Nerve Injury-Induced Neuropathic Pain in Mice by Inhibiting Microglia Activation and Neuronal Oxidative Damage in the Spinal Cord via the AMPK Pathway.
Inhibition of pyruvate carboxylase reverses metformin resistance by activating AMPK in pancreatic cancer.
Metformin ameliorates ferroptosis in cardiac ischemia and reperfusion by reducing NOX4 expression via promoting AMPKα.
iPSCs ameliorate hypoxia-induced autophagy and atrophy in C2C12 myotubes via the AMPK/ULK1 pathway.

Mar Life Sci Technol. 2023 May;5(2): 196-210

Discovery of a natural small-molecule AMP-activated kinase activator that alleviates nonalcoholic steatohepatitis.

Jin Chen, Li Xu, Xue-Qing Zhang, Xue Liu, Zi-Xuan Zhang, Qiu-Mei Zhu, Jian-Yu Liu, Muhammad Omer Iqbal, Ning Ding, Chang-Lun Shao, Mei-Yan Wei, Yu-Chao Gu.

  Non-alcoholic steatohepatitis (NASH) is a primary cause of cirrhosis and hepatocellular carcinoma. Unfortunately, there is no approved drug treatment for NASH. AMP-activated kinase (AMPK) is an important metabolic sensor and whole-body regulator. It has been proposed that AMPK activators could be used for treating metabolic diseases such as obesity, type 2 diabetes and NASH. In this study, we screened a marine natural compound library by monitoring AMPK activity and found a potent AMPK activator, candidusin A (CHNQD-0803). Further studies showed that CHNQD-0803 directly binds recombinant AMPK with a KD value of 4.728 × 10-8 M and activates AMPK at both molecular and intracellular levels. We then investigated the roles and mechanisms of CHNQD-0803 in PA-induced fat deposition, LPS-stimulated inflammation, TGF-β-induced fibrosis cell models and the MCD-induced mouse model of NASH. The results showed that CHNQD-0803 inhibited the expression of adipogenesis genes and reduced fat deposition, negatively regulated the NF-κB-TNFα inflammatory axis to suppress inflammation, and ameliorated liver injury and fibrosis. These data indicate that CHNQD-0803 as an AMPK activator is a novel potential therapeutic candidate for NASH treatment.Supplementary Information: The online version contains supplementary material available at 10.1007/s42995-023-00168-z.

Keywords:  AMPK; Fibrosis; Inflammation; Lipid metabolism; Marine drug; NASH

DOI:  https://doi.org/10.1007/s42995-023-00168-z
J Cell Biochem. 2023 Jun 03.

Sweroside alleviates hepatic steatosis in part by activating AMPK/mTOR-mediated autophagy in mice.

Yan Ding, Yuefu Chen, Ke Hu, Qiansheng Yang, Yuxian Li, Minjiang Huang.

  In this study, we investigated the effect of sweroside (SOS) on hepatic steatosis in mice and elucidated its molecular mechanisms. We conducted in vivo experiments using a C57BL/6 mice model of nonalcohol fatty liver disease (NAFLD) to explore the effect of SOS on hepatic steatosis in NAFLD mice. In in vitro experiments, primary mouse hepatocytes were treated with palmitic acid and SOS, and the protective effects of SOS on inflammation, lipogenesis, and fat deposition were analyzed. Autophagy-related protein levels and their related signaling pathways were evaluated in both in vivo and in vitro experiments. The results demonstrated that SOS decreased the high-fat-induced intrahepatic lipid content both in vivo and in vitro. The autophagy level in the liver was decreased in NAFLD mice but was reactivated following SOS intervention. SOS intervention was found to partially activate autophagy via the adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signaling pathway. Consequently, when the AMPK/mTOR pathway was suppressed or autophagy was inhibited, the beneficial effects of SOS intervention on hepatic steatosis were diminished. These results indicate that SOS intervention attenuates hepatic steatosis by promoting autophagy in the liver of NAFLD mice, in part by activating the AMPK/mTOR signaling pathway.

Keywords:  autophagy; nonalcoholic fatty liver disease; sweroside

DOI:  https://doi.org/10.1002/jcb.30428
Life Sci. 2023 Jun 02. pii: S0024-3205(23)00450-2. [Epub ahead of print] 121816

Patulin alleviates hepatic lipid accumulation by regulating lipogenesis and mitochondrial respiration.

Seungmin Yu, Ji-Hye Song, Hee Soo Kim, Seulmin Hong, Seon Kyeong Park, Soo Hyun Park, Jangho Lee, Young Chan Chae, Jae Ho Park, Yu Geon Lee.

  AIMS: The aim of this study is to evaluate the effects of patulin on hepatic lipid metabolism and mitochondrial oxidative function and elucidate the underlying molecular mechanisms.MAIN METHODS: The effects of patulin on hepatic lipid accumulation were evaluated in free fatty acid-treated AML12 or HepG2 cells through oil red O staining, triglyceride assay, real-time polymerase chain reaction, and western blotting. Alteration of mitochondrial oxidative capacity by patulin treatment was determined using Seahorse analysis to measure the oxygen consumption rate.
KEY FINDINGS: The increased amounts of lipid droplets induced by free fatty acids were significantly reduced by patulin treatment. Patulin markedly activated the CaMKII/AMP-activated protein kinase (AMPK)/proliferator-activated receptor-γ coactivator (PGC)-1α signaling pathway in hepatocytes, reduced the expression of sterol regulatory element binding protein 1c (SREBP-1c) and lipogenic genes, and increased the expression of genes related to mitochondrial fatty acid oxidation. In addition, patulin treatment enhanced the mitochondrial consumption rate and increased the expression of mitochondrial oxidative phosphorylation proteins in HepG2 hepatocytes. The effects of patulin on anti-lipid accumulation; SREBP-1c, PGC-1α, and carnitine palmitoyltransferase 1 expression; and mitochondrial oxidative capacity were significantly prevented by compound C, an AMPK inhibitor.
SIGNIFICANCE: Patulin is a potent inducer of the AMPK pathway, and AMPK-mediated mitochondrial activation is required for the efficacy of patulin to inhibit hepatic lipid accumulation. This study is the first to report that patulin is a promising bioactive compound that prevents the development and worsening of fatty liver diseases, including non-alcoholic fatty liver disease, by improving mitochondrial quality and lipid metabolism.

Keywords:  AMPK; Fatty acid oxidation; Lipid accumulation; Mitochondrial respiration; Patulin

DOI:  https://doi.org/10.1016/j.lfs.2023.121816
ACS Chem Neurosci. 2023 Jun 07.

Mitochondrial-Derived Peptide MOTS-c Ameliorates Spared Nerve Injury-Induced Neuropathic Pain in Mice by Inhibiting Microglia Activation and Neuronal Oxidative Damage in the Spinal Cord via the AMPK Pathway.

Jinhong Jiang, Lingfei Xu, Long Yang, Su Liu, Zhe Wang.

  MOTS-c, a recently discovered mitochondrial-derived peptide, plays an important role in many physiological and pathological functions via adenosine monophosphate-activated protein kinase (AMPK) activation. Numerous studies have demonstrated that AMPK is an emerging target for the modulation of neuropathic pain. Meanwhile, microglia-activation-evoked neuroinflammation is known to contribute to the development and progression of neuropathic pain. MOTS-c is also known to inhibit microglia activation, chemokine and cytokine expression, and innate immune responses. Accordingly, in this study, we evaluated the effects of MOTS-c on neuropathic pain and investigated the putative underlying mechanisms. We found that MOTS-c levels in plasma and spinal dorsal horn were significantly lower in mice with spared nerve injury (SNI)-induced neuropathic pain than in control animals. Accordingly, MOTS-c treatment produced pronounced dose-dependent antinociceptive effects in SNI mice; however, these effects were blocked by dorsomorphin, an AMPK inhibitor, but not naloxone, a nonselective opioid receptor antagonist. Moreover, intrathecal (i.t.) injection of MOTS-c significantly enhanced AMPKα1/2 phosphorylation in the lumbar spinal cord of SNI mice. MOTS-c also significantly inhibited proinflammatory cytokine production and microglia activation in the spinal cord. The antinociceptive effects of MOTS-c were retained even when microglia activation in the spinal cord was inhibited by minocycline pretreatment, indicating that spinal cord microglia are dispensable for the antiallodynic effects of MOTS-c. In the spinal dorsal horn, MOTS-c treatment inhibited c-Fos expression and oxidative damage mainly in neurons rather than microglia. Finally, in contrast to morphine, i.t. administration of MOTS-c resulted in limited side effects relating to antinociceptive tolerance, gastrointestinal transit inhibition, locomotor function, and motor coordination. Collectively, the present study is the first to provide evidence that MOTS-c may be a promising therapeutic target for neuropathic pain.

Keywords:  AMPK; MOTS-c; antinociception; c-fos; microglia; neuropathic pain

DOI:  https://doi.org/10.1021/acschemneuro.3c00140
Life Sci. 2023 Jun 02. pii: S0024-3205(23)00451-4. [Epub ahead of print]327 121817

Inhibition of pyruvate carboxylase reverses metformin resistance by activating AMPK in pancreatic cancer.

Chang Liu, Xiang Zhou, Huijun Ju, Yifan Zhang.

  AIMS: Pyruvate carboxylase (PC) plays a key role in cancer cell metabolic reprogramming. Whether metabolic reprogramming and PC are related in PDAC is unclear. Here, the effect of PC expression on PDAC tumorigenesis and metabolic reprogramming were evaluated.MATERIALS AND METHODS: PC protein expression in PDAC and precancerous tissues was measured through immunohistochemistry. The maximum standardized uptake (SUVmax) of 18F-fluoro-2-deoxy-2-d-glucose (18F-FDG) in PDAC patient PET/CT scans before surgical resection was retrospectively determined. Stable PC-knockdown and PC-overexpressing cells were established using lentiviruses, and PDAC progression was assessed in vivo and in vitro. Lactate content, 18F-FDG cell uptake rate, mitochondrial oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) were measured in cells. RNA sequencing revealed and qPCR verified differentially expressed genes (DEGs) after PC knockdown. The signaling pathways involved were determined by Western blotting.
KEY FINDINGS: PC was significantly upregulated in PDAC tissues vs. precancerous tissues. A high SUVmax correlated with PC upregulation. PC knockdown significantly inhibited PDAC progression. Lactate content, SUVmax, and ECAR significantly decreased after PC knockdown. Peroxisome proliferator-activated receptor gamma coactivator-one alpha (PGC-1α) was upregulated after PC knockdown; and PGC1a expression promoted AMPK phosphorylation to activate mitochondrial metabolism. Metformin significantly inhibited mitochondrial respiration after PC knockdown, further activated AMPK and downstream carnitine palmitoyltransferase 1A (CPT1A)-regulated fatty acid oxidation (FAO), and inhibited PDAC cells progression.
SIGNIFICANCE: PDAC cell uptake of FDG was positively correlated with PC expression. PC promotes PDAC glycolysis, and reducing PC expression can increase PGC1a expression, activate AMPK, and restore metformin sensitivity.

Keywords:  FDG uptake; Metformin; OXPHOS; PC; PDAC; PGC-1α

DOI:  https://doi.org/10.1016/j.lfs.2023.121817
Pharm Biol. 2023 Dec;61(1): 886-896

Metformin ameliorates ferroptosis in cardiac ischemia and reperfusion by reducing NOX4 expression via promoting AMPKα.

Zhenhua Wu, Yunpeng Bai, Yujuan Qi, Chao Chang, Yan Jiao, Yaobang Bai, Zhigang Guo.

  CONTEXT: Metformin (Met) has a protective effect against cardiac ischemia and reperfusion (I/R) injury.OBJECTIVE: This study uncovered the Met effect on ferroptosis in cardiac I/R.
MATERIALS AND METHODS: Sprague-Dawley rats underwent cardiac I/R treatment (ischaemia 30 min; reperfusion 24 h) (I/R group), and administered intravenously with Met (200 mg/kg) (I/R + Met group). Haematoxylin-eosin staining, Prussian blue staining, immunohistochemistry and transmission electron microscope were conducted on cardiac tissues. H9c2 cells underwent oxygen-glucose deprivation/reoxygenation (OGD/R group) and treated by Met (0.1 mM) (OGD/R + Met group). Adenosine monophosphate-activated protein kinase α (AMPKα) siRNA was transfected into OGD/R-induced H9c2 cells. Cell counting kit-8 (CCK-8) assay, dichloro-dihydro-fluorescein diacetate (DCFH-DA) and JC-1 staining were conducted on H9c2 cells. Ferroptosis-related indicators and gene expression were detected by enzyme-linked immunosorbent assay (ELISA), quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot.
RESULTS: In cardiac I/R rat, Met decreased heart and serum MDA, cardiac and serum non-heme iron, and serum CK-MB and LDH (inhibition rate: 50.0%, 48.8%, 47.6%, 29.5%, 30.6% and 34.7%, respectively), relieved cardiac tissue ferroptosis and mitochondria damage, increased fraction shortening and ejection fraction (157.5% and 146.2% on day 28, respectively), up-regulated AMPKα and down-regulated NOX4 in cardiac tissues. In OGD/R-induced H9c2 cells, Met (0.1 mM) increased cell viability (promotion rate: 170.0%), decreased non-heme iron and MDA (inhibition rate: 30.1% and 47.9%, respectively), relieved ferroptosis, up-regulated AMPKα and down-regulated NOX4. AMPKα silencing abrogated these effects of Met on the OGD/R-induced H9c2 cells.
DISCUSSION AND CONCLUSIONS: Met shows effectiveness in relieving ferroptosis in cardiac I/R. In the future, Met may be an effective drug for relieving ferroptosis in cardiac I/R patients clinically.

Keywords:  LDH; MDA; Mitochondrial damage; ROS; non-heme iron

DOI:  https://doi.org/10.1080/13880209.2023.2212700
Biol Res. 2023 Jun 03. 56(1): 29

iPSCs ameliorate hypoxia-induced autophagy and atrophy in C2C12 myotubes via the AMPK/ULK1 pathway.

Haimei Cen, Pin Fan, Yuting Ding, Bin Luo, Hong Luo, Menglong Chen, Yu Zhang.

  BACKGROUND: Duchenne muscular dystrophy (DMD) is an X-linked lethal genetic disorder for which there is no effective treatment. Previous studies have shown that stem cell transplantation into mdx mice can promote muscle regeneration and improve muscle function, however, the specific molecular mechanisms remain unclear. DMD suffers varying degrees of hypoxic damage during disease progression. This study aimed to investigate whether induced pluripotent stem cells (iPSCs) have protective effects against hypoxia-induced skeletal muscle injury.RESULTS: In this study, we co-cultured iPSCs with C2C12 myoblasts using a Transwell nested system and placed them in a DG250 anaerobic workstation for oxygen deprivation for 24 h. We found that iPSCs reduced the levels of lactate dehydrogenase and reactive oxygen species and downregulated the mRNA and protein levels of BAX/BCL2 and LC3II/LC3I in hypoxia-induced C2C12 myoblasts. Meanwhile, iPSCs decreased the mRNA and protein levels of atrogin-1 and MuRF-1 and increased myotube width. Furthermore, iPSCs downregulated the phosphorylation of AMPKα and ULK1 in C2C12 myotubes exposed to hypoxic damage.
CONCLUSIONS: Our study showed that iPSCs enhanced the resistance of C2C12 myoblasts to hypoxia and inhibited apoptosis and autophagy in the presence of oxidative stress. Further, iPSCs improved hypoxia-induced autophagy and atrophy of C2C12 myotubes through the AMPK/ULK1 pathway. This study may provide a new theoretical basis for the treatment of muscular dystrophy in stem cells.

Keywords:  AMPK/ULK1 pathway; Atrogin-1; Co-culture; Duchenne muscular dystrophy; Hypoxia; LC3II/LC3I; MuRF-1

DOI:  https://doi.org/10.1186/s40659-023-00435-4