bims-amsmem 2023-03-26 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2023–03–26
eleven papers selected by
Dipsikha Biswas, Københavns Universitet

Activation of AMP-activated protein kinase (AMPK) through inhibiting interaction with prohibitins.
Gradual deterioration of fatty liver disease to liver cancer via inhibition of AMPK signaling pathways involved in energy-dependent disorders, cellular aging, and chronic inflammation.
Effects of protocatechuic acid on antioxidant capacity, mitochondrial biogenesis and skeletal muscle fiber transformation.
NR3C2 inhibits the proliferation of colorectal cancer via regulating glucose metabolism and phosphorylating AMPK.
Metformin promotes osteogenic differentiation and prevents hyperglycaemia-induced osteoporosis by suppressing PPARγ expression.
Irisin Ameliorates PM2.5-Induced Acute Lung Injury by Regulation of Autophagy Through AMPK/mTOR Pathway.
Ginsenoside Rg1 Ameliorates Pancreatic Injuries via the AMPK/mTOR Pathway in vivo and in vitro.
Nicaraven protects against endotoxemia-induced inflammation and organ injury through modulation of AMPK/Sirt1 signaling in macrophages.
Role of Autophagy Mediated by AMPK/DDiT4/mTOR Axis in HT22 Cells Under Oxygen and Glucose Deprivation/Reoxygenation.
Muscle PARP1 inhibition extends lifespan through AMPKα PARylation and activation in Drosophila.
Sertoli cell adaptation to glucose deprivation: Potential role of AMPK in the regulation of lipid metabolism.

iScience. 2023 Apr 21. 26(4): 106293

Activation of AMP-activated protein kinase (AMPK) through inhibiting interaction with prohibitins.

Shuhei Kanagaki, Yusuke Tsutsui, Naoki Kobayashi, Takashi Komine, Minoru Ito, Yunike Akasaka, Michiaki Nagasawa, Tomohiro Ide, Naoki Omae, Kazuhisa Nakao, Makoto Rembutsu, Maki Iwago, Aki Yonezawa, Yusei Hosokawa, Tetsuya Hosooka, Wataru Ogawa, Koji Murakami.

  5'-Adenosine monophosphate-activated protein kinase (AMPK) is a potential therapeutic target for various medical conditions. We here identify a small-molecule compound (RX-375) that activates AMPK and inhibits fatty acid synthesis in cultured human hepatocytes. RX-375 does not bind to AMPK but interacts with prohibitins (PHB1 and PHB2), which were found to form a complex with AMPK. RX-375 induced dissociation of this complex, and PHBs knockdown resulted in AMPK activation, in the cultured cells. Administration of RX-375 to obese mice activated AMPK and ameliorated steatosis in the liver. High-throughput screening based on disruption of the AMPK-PHB interaction identified a second small-molecule compound that activates AMPK, confirming the importance of this interaction in the regulation of AMPK. Our results thus indicate that PHBs are previously unrecognized negative regulators of AMPK, and that compounds that prevent the AMPK-PHB interaction constitute a class of AMPK activator.

Keywords:  Biochemistry; Endocrinology; Small molecule

DOI:  https://doi.org/10.1016/j.isci.2023.106293
Front Oncol. 2023 ;13 1099624

Gradual deterioration of fatty liver disease to liver cancer via inhibition of AMPK signaling pathways involved in energy-dependent disorders, cellular aging, and chronic inflammation.

Sha-Sha Meng, Hong-Wei Gu, Ting Zhang, Yu-Sang Li, He-Bin Tang.

   Introduction: Hepatocellular carcinoma (HCC) is the most prevalent primary liver cancer kind. According to recent research, a fatty liver increases the risk of hepatocellular cancer. Nevertheless, the AMPK signaling pathway is crucial. In addition, 5'-AMP-activated protein kinase (AMPK) is strongly linked to alterations in the tumor microenvironment, such as inflammation, hypoxia, and aging. The objective of this study is to evaluate the impact of the AMPK signaling pathway on the progression of fatty liver to HCC.
Methods: In this study, we established a mouse liver cancer model using high-fat diets and nano-nitrosamines (nano-DEN). In addition, we employed a transcriptomic technique to identify all mRNAs detected in liver samples at the 25th weekexpression of proteins linked with the LKB1-AMPK-mTOR signaling pathway, inflammation, aging, and hypoxia was studied in microarrays of liver cancer tissues from mice and humans. These proteins included p-AMPK, LKB1, mTOR, COX-2, β-catenin, HMGB1, p16, and HIF-1α.
Results: Data were collected at different times in the liver as well as in cancerous and paracancerous regions and analyzed by a multispectral imaging system. The results showed that most of the genes in the AMPK signaling pathway were downregulated. Prakk1 expression was upregulated compared to control group but downregulated in the cancerous regions compared to the paracancerous regions. Stk11 expression was downregulated in the cancerous regions. Mtor expression was upregulated in the cancerous regions. During liver cancer formation, deletion of LKB1 in the LKB1-AMPK-mTOR signaling pathway reduces phosphorylation of AMPK. It contributed to the upregulation of mTOR, which further led to the upregulation of HIF1α. In addition, the expression of β-catenin, COX-2, and HMGB1 were upregulated, as well as the expression of p16 was downregulated.
Discussion: These findings suggest that changes in the AMPK signaling pathway exacerbate the deterioration of disrupted energy metabolism, chronic inflammation, hypoxia, and cellular aging in the tumor microenvironment, promoting the development of fatty liver into liver cancer.

Keywords:  AMPK; aging; fatty Liver; hypoxia; inflammation; liver cancer; tumor microenvironment

DOI:  https://doi.org/10.3389/fonc.2023.1099624
J Nutr Biochem. 2023 Mar 21. pii: S0955-2863(23)00060-8. [Epub ahead of print] 109327

Effects of protocatechuic acid on antioxidant capacity, mitochondrial biogenesis and skeletal muscle fiber transformation.

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

  In skeletal muscle, the increased proportion of type I muscle fibers has the potential to improve muscle atrophy and prevent human metabolic diseases. Protocatechuic acid (PCA), as a kind of anthocyanin metabolite, has antioxidant and anti-inflammatory physiological activities. The purpose of this experiment was to use mice and C2C12 myotubes to examine if PCA can induce the transformation of muscle fiber and the mechanisms involved. We found that PCA significantly increased the expression of slow myosin heavy chain (MyHC), and markedly decreased the expression of fast MyHC in gastrocnemius muscle of mice and C2C12 myotubes. In addition, PCA also enhanced the antioxidant capacity and promoted mitochondrial biogenesis in mice. Importantly, the AMP-activated protein kinase (AMPK) signaling pathway was activated and AMPK inhibitor compound C attenuated the positive effect of PCA on myofiber conversion. To sum up, we revealed that PCA was able to promote the conversion of skeletal muscle fiber from type II to type I through the AMPK signaling pathway.

Keywords:  AMPK signaling pathway; Mitochondrial function; Muscle fiber transformation; Protocatechuic acid; Skeletal muscle

DOI:  https://doi.org/10.1016/j.jnutbio.2023.109327
J Cell Mol Med. 2023 Mar 23.

NR3C2 inhibits the proliferation of colorectal cancer via regulating glucose metabolism and phosphorylating AMPK.

Hui Liu, Wenqi Lei, Zhigui Li, Xiaodong Wang, Liming Zhou.

  We aim to investigate the roles and mechanisms of NR3C2 in colorectal cancer (CRC). The expression of NR3C2 in CRC tumours and paired paracancerous tissues of 71 CRC patients and five CRC cell lines was detected by western blotting, immunohistochemistry and real-time reverse-transcription PCR. Moreover, NR3C2 was overexpressed or knocked down in CRC cells by lentiviral vector transfection. The proliferation of cells was measured by MTT, colony formation assay and flow cytometry. Glucose metabolism was assessed by detecting lactate production, glucose consumption and ATP production. Western blotting and real-time reverse-transcription PCR were used to detect the expression of AMPK, LDHA and HK2. The expression of NR3C2 was significantly decreased in CRC tumours compared to paracancerous tissues, which was correlated with distant metastasis, poor prognosis and advanced stages of CRC patients. Overexpressing NR3C2 suppressed the proliferation and promoted the G2/M cell cycle arrest of CRC cells. Furthermore, NR3C2 inhibited glucose metabolism by decreasing the expression of HK2 and LDHA. The phosphorylation of AMPK was also downregulated in CRC cells overexpressing NR3C2. This study demonstrated that NR3C2 inhibited the proliferation of CRC by inhibiting glucose metabolism and phosphorylation of AMPK which may serve as a therapeutic target for CRC.

Keywords:  AMPK; NR3C2; colorectal cancer; glucose metabolism

DOI:  https://doi.org/10.1111/jcmm.17706
Acta Biochim Biophys Sin (Shanghai). 2023 Mar 25.

Metformin promotes osteogenic differentiation and prevents hyperglycaemia-induced osteoporosis by suppressing PPARγ expression.

Lifeng Zheng, Ximei Shen, Yun Xie, Hong Lian, Sunjie Yan, Shizhong Wang.

  Metformin can prevent hyperglycaemia-induced osteoporosis and decrease the bone fracture rate, but the mechanism has not been fully elucidated. To reveal the mechanism by which metformin affects hyperglycaemia-induced osteoporosis, we treat a mouse osteoporosis cell model with metformin and find that osteoblast mineralization increases and PPARγ expression decreases. Single-cell mRNA sequencing analysis show that PPARγ is highly expressed in the bone tissue of osteoporosis patients, which highlights the role of PPARγ in osteoporosis. Furthermore, we find that PPARγ is the effector through which metformin prevents osteoporosis. We further examine the mechanism of PPARγ regulation and reveal that metformin regulates PPARγ expression through the AMPK pathway and that PPARγ affects osteoblasts through the endoplasmic reticulum stress (ERS) pathway. Moreover, we verify the association between the effect of metformin on bone metabolism and the expression of PPARγ in high-fat diet-induced diabetic rats. Thus, we identify and functionally validate that metformin prevents hyperglycaemia-induced osteoporosis by regulating the AMPK-PPARγ-ERS axis.

Keywords:  Diabetes; Endoplasmic reticulum stress; Metformin; Osteoporosis; PPARγ

DOI:  https://doi.org/10.3724/abbs.2023043
J Inflamm Res. 2023 ;16 1045-1057

Irisin Ameliorates PM2.5-Induced Acute Lung Injury by Regulation of Autophagy Through AMPK/mTOR Pathway.

Jiao Ma, Zhuoxiao Han, Rui Jiao, Guanli Yuan, Cuiqing Ma, Xixin Yan, Aihong Meng.

   Background: PM2.5 exposure is one of the major inducements of various respiratory diseases and related mortality. Meanwhile, irisin, a metabolism and thermogenesis-related hormone, is found to be protective against acute lung injury induced by LPS, which indicates its therapeutic function in lung injury. However, the function and underlying mechanism of irisin in PM2.5-induced acute lung injury (ALI) are still unclear. This study is aimed to discover the potential mechanisms of irisin in PM2.5-induced acute lung injury.
Methods: Atg5 deficient mice and cells were established to clarify the relationship between irisin and autophagy in PM2.5-induced ALI. We also used Ad-mCherry-GFP-LC3B as a monitor of autophagy flux to claim the effects of irisin on autophagy. Western blotting and qPCR were used to reveal the molecular mechanism.
Results: As a result, PM2.5 exposure induced lung injury whereas mitigated by irisin. Moreover, PM2.5 hampered autophagy flux, characterized by accumulation of p62, and autophagosomes, as well as blocked autolysosomes. Irisin improved the disturbed autophagy flux, which was abrogated by deficiency of Atg5. Additionally, we demonstrated that irisin activated AMPK and inhibited mTOR, which indicated the enhanced autophagy. Moreover, blockage of AMPK by compound C terminated irisin's induction of autophagy in cultured MH-S cells.
Conclusion: Our findings reveal that irisin performs protective effects against PM2.5-induced ALI by activating autophagy through AMPK/mTOR signaling pathway.

Keywords:  PM2.5; acute lung injury; autophagy; irisin

DOI:  https://doi.org/10.2147/JIR.S390497
Diabetes Metab Syndr Obes. 2023 ;16 779-794

Ginsenoside Rg1 Ameliorates Pancreatic Injuries via the AMPK/mTOR Pathway in vivo and in vitro.

Jin Chen, Guoping Zhu, Wenbo Xiao, Xiaosong Huang, Kewu Wang, Yi Zong.

   Background: The main propanaxatriol-type saponin found in ginseng (Panax ginseng C. A. Mey), ginsenoside Rg1 (G-Rg1), has bioactivities that include anti-inflammatory, antioxidant, and anti-diabetic properties. This study aimed to investigate the effects of G-Rg1 on streptozotocin (STZ)-induced Type 1 Diabetes mellitus (T1DM) mice and the insulin-secreting cell line in RIN-m5F cells with high-glucose (HG) treatment.
Methods: The STZ-induced DM mice model was treated with G-Rg1 alone or combined with 3-Methyladenine (3-MA, an autophagy inhibitor)/rapamycin (RAPA, an autophagy activator) for 8 weeks, and levels of glucose and lipid metabolism, histopathological changes, as well as autophagy and apoptosis of relevant markers were estimated. In vitro, the HG-induced RIN-m5F cells were treated with G-Rg1, 3-MA, and Compound C (CC), an AMPK inhibitor, or their combinations to estimate the influences on cell apoptosis, autophagy, and AMPK/mTOR pathway-associated target gene levels.
Results: G-Rg1 treatment attenuated glucose and lipid metabolism disorder and pancreatic fibrosis in diabetic mice. In addition, subdued autophagy and p-AMPK protein expression, and enhanced p-mTOR protein expression and apoptosis levels in TIDM mice and HG-induced RIN-m5F cells were ameliorated by G-Rg1 treatment. Furthermore, these anti-apoptosis effects of G-Rg1 were partially abolished by 3-MA and CC.
Conclusion: Our findings revealed that G-Rg1 exhibits strong anti-apoptosis ability in pancreatic tissues of type 1 diabetic mice and HG-induced RIN-m5F cells, and the mechanisms involved in activating AMPK and inhibiting mTOR-mediated autophagy, indicating that G-Rg1 may have the therapeutic and preventive potential for treating pancreatic injury in diabetic patients.

Keywords:  AMPK; apoptosis; autophagy; diabetes mellitus; ginsenoside Rg1

DOI:  https://doi.org/10.2147/DMSO.S401642
Eur J Pharmacol. 2023 Mar 20. pii: S0014-2999(23)00177-2. [Epub ahead of print]946 175666

Nicaraven protects against endotoxemia-induced inflammation and organ injury through modulation of AMPK/Sirt1 signaling in macrophages.

Duoduo Zha, Yaqin Yang, Xiang Huang, Ziwei Wang, Hongru Lin, Lingyi Yang, Luyan Xu, Yijia Wu, Houda Huang, Yihan Wang, Zhaochen Xin, Xuehan Wu, Yun-Fei Xiao, Tao-Sheng Li, Ke-Yu Deng, Hong-Bo Xin, Yisong Qian.

  Endotoxemia is a disease characterized by systemic inflammatory responses and organ injury caused by lipopolysaccharide (LPS) infection, with high mortality. Nicaraven (AVS), a potent hydroxyl radical scavenger, has been proven to regulate the inflammatory response in tumors. To investigate the protective effects and mechanisms of AVS in endotoxemia, mice were injected intraperitoneally with LPS to induce endotoxemia. AVS treatment significantly decreased the levels of pro-inflammatory cytokines in the serum, reduced neutrophil infiltration, attenuated multiple organ injury, and increased the survival rate in LPS-challenged mice. In the LPS-induced inflammatory model of macrophages, AVS inhibited macrophage activation, suppressed nitric oxide (NO) production, and inhibited the expression and secretion of pro-inflammatory cytokines. Mechanistically, AVS treatment up-regulated silence information regulator transcript-1 (Sirt1) expression in a time- and dose-dependent manner. AVS treatment activated the AMP-dependent protein kinase (AMPK)/Sirt1 signaling pathway and suppressed the activation of nuclear factor kappa B (NF-κB) in macrophages exposed to LPS. However, the anti-inflammatory effects of AVS could be reversed by the AMPK, the Sirt1 inhibitor, or the histone deacetylase inhibitor. We confirmed that the AMPK inhibitor inhibited AVS-mediated AMPK/Sirt1 activation and NF-κB p65 acetylation. These results suggested that AVS alleviated endotoxemia by activating the AMPK/Sirt1 signaling pathway in macrophages.

Keywords:  AVS; Endotoxemia; Inflammation; Macrophage; Sirt1

DOI:  https://doi.org/10.1016/j.ejphar.2023.175666
ACS Omega. 2023 Mar 14. 8(10): 9221-9229

Role of Autophagy Mediated by AMPK/DDiT4/mTOR Axis in HT22 Cells Under Oxygen and Glucose Deprivation/Reoxygenation.

Yi Zhang, Luyao Liu, Xianming Hou, Ziwei Zhang, Xiaohong Zhou, Weijuan Gao.

Background: cerebral ischemia/reperfusion (I/R) injury is an important complication of ischemic stroke, and autophagy is one of the mechanisms of it. In this study, we aimed to determine the role and mechanism of autophagy in cerebral I/R injury. Methods: the oxygen and glucose deprivation/reoxygenation (OGD/R) method was used to model cerebral I/R injury in HT22 cells. CCK-8 and LDH were conducted to detect viability and damage of the cells, respectively. Apoptosis was measured by flow cytometry and Tunel staining. Autophagic vesicles of HT22 cells were assessed by transmission electron microscopy. Western blotting analysis was used to examine the protein expression involving AMPK/DDiT4/mTOR axis and autophagy-related proteins. 3-Methyladenine and rapamycin were, respectively, used to inhibit and activate autophagy, compound C and AICAR acted as AMPK inhibitor and activator, respectively, and were used to control the starting link of AMPK/DDiT4/mTOR axis. Results: autophagy was activated in HT22 cells after OGD/R was characterized by an increased number of autophagic vesicles, the expression of Beclin1 and LC3II/LC3I, and a decrease in the expression of P62. Rapamycin could increase the viability, reduce LDH leakage rate, and alleviate cell apoptosis in OGD/R cells by activating autophagy. 3-Methyladenine played an opposite role to rapamycin in OGD/R cells. The expression of DDiT4 and the ratio of p-AMPK/AMPK were increased after OGD/R in HT22 cells. While the ratio of p-mTOR/mTOR was reduced by OGD/R, AICAR effectively increased the number of autophagic vesicles, improved viability, reduced LDH leakage rate, and alleviated apoptosis in HT22 cells which suffered OGD/R. However, the effects of compound C in OGD/R HT22 cells were opposite to that of AICAR. Conclusions: autophagy is activated after OGD/R; autophagy activator rapamycin significantly enhanced the protective effect of autophagy on cells of OGD/R. AMPK/DDiT4/mTOR axis is an important pathway to activate autophagy, and AMPK/DDiT4/mTOR-mediated autophagy significantly alleviates cell damage caused by OGD/R.

DOI: https://doi.org/10.1021/acsomega.2c07280
Proc Natl Acad Sci U S A. 2023 Mar 28. 120(13): e2213857120

Muscle PARP1 inhibition extends lifespan through AMPKα PARylation and activation in Drosophila.

Shanshan Guo, Shuang Zhang, Yixiao Zhuang, Famin Xie, Ruwen Wang, Xingyu Kong, Qiongyue Zhang, Yonghao Feng, Huanqing Gao, Xingxing Kong, Tiemin Liu.

  Poly(ADP-ribose) polymerase-1 (PARP1) has been reported to play an important role in longevity. Here, we showed that the knockdown of the PARP1 extended the lifespan of Drosophila, with particular emphasis on the skeletal muscle. The muscle-specific mutant Drosophila exhibited resistance to starvation and oxidative stress, as well as an increased ability to climb, with enhanced mitochondrial biogenesis and activity at an older age. Mechanistically, the inhibition of PARP1 increases the activity of AMP-activated protein kinase alpha (AMPKα) and mitochondrial turnover. PARP1 could interact with AMPKα and then regulate it via poly(ADP ribosyl)ation (PARylation) at residues E155 and E195. Double knockdown of PARP1 and AMPKα, specifically in muscle, could counteract the effects of PARP1 inhibition in Drosophila. Finally, we showed that increasing lifespan via maintaining mitochondrial network homeostasis required intact PTEN induced kinase 1 (PINK1). Taken together, these data indicate that the interplay between PARP1 and AMPKα can manipulate mitochondrial turnover, and be targeted to promote longevity.

Keywords:  PARP1; PARylation; longevity; mitochondria

DOI:  https://doi.org/10.1073/pnas.2213857120
J Cell Biochem. 2023 Mar 22.

Sertoli cell adaptation to glucose deprivation: Potential role of AMPK in the regulation of lipid metabolism.

Gustavo M Rindone, Marina E Dasso, Cecilia L Centola, Eliana H Pellizzari, María Del C Camberos, Judith Toneatto, María N Galardo, Silvina B Meroni, María F Riera.

  Sertoli cells (SCs) provide an adequate environment for germ cell development. SCs possess unique features that meet germ cells' metabolic demands: they produce lactate from glucose, which is delivered as energy substrate to germ cells. SCs store fatty acids (FAs) as triacylglycerols (TAGs) in lipid droplets (LDs) and can oxidize FAs to sustain their own energetic demands. They also produce ketone bodies from FAs. It has been shown that exposure of SCs to metabolic stresses, such as glucose deprivation, triggers specific adaptive responses that sustain cell survival and preserve lactate supply to germ cells. The aim of the present study was to investigate whether there are modifications in rat SCs lipid metabolism, including LD content, FA oxidation, and ketone bodies production, as part of their adaptive response to glucose deprivation. The present study was performed in 20-day-old rat SCs cultures. We determined LD content by Oil Red O staining, FA oxidation by measuring the release of 3 H2 O from [3 H] palmitate, TAGs and 3-hydroxybutyrate levels by spectrophotometric methods, and mRNA levels by RT-qPCR. Results show that the absence of glucose in SC culture medium entails: (1) a decrease in LD content and TAGs levels that is accompanied by decreased perilipin 1 mRNA levels, (2) an increase in FA oxidation that is in part mediated by AMP kinase (AMPK) activation and (3) a decrease in 3-hydroxybutyrate production. Additionally, we studied whether sestrins (SESN1, 2 and 3), proteins involved in the cellular response to stress, are regulated in glucose deprivation conditions. We show that there is an increase in SESN2 mRNA levels in deprived conditions. In conclusion, glucose deprivation affects SC lipid metabolism promoting FA mobilization from LDs to be used as energy source.

Keywords:  AMPK; SESN2; fatty acid oxidation; ketone bodies; lipid droplets; sertoli cells; testis

DOI:  https://doi.org/10.1002/jcb.30399