bims-amsmem 2022-08-28 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2022–08–28
nineteen papers selected by
Dipsikha Biswas, Københavns Universitet

AMPKβ isoform expression patterns in various adipocyte models and in relation to body mass index.
Targeting AMPK Signaling in the Liver: Implications for Obesity and Type 2 Diabetes Mellitus.
Impact of 5'-AMP-activated protein kinase (AMPK) on Epithelial Sodium Channels (ENaCs) in human sperm.
PFOS promotes hepatic lipid accumulation and steatosis in high-fat diet mice through AMPK/ACC pathway.
AMPK promotes Arf6 activation in a kinase-independent manner upon energy deprivation.
AMPK suppresses Th2 cell responses by repressing mTORC2.
PHLPP1 regulates CFTR activity and lumen expansion through AMPK.
Gryllus bimaculatus extract ameliorates high-fat diet-induced hyperglycemia and hyperlipidemia by inhibiting hepatic lipogenesis through AMPK activation.
Cladrin alleviates dexamethasone-induced apoptosis of osteoblasts and promotes bone formation through autophagy induction via AMPK/mTOR signaling.
miR-130b/301b is a Negative Regulator of Beige Adipogenesis and Energy Metabolism in vitro and in vivo.
The AMPK-HOXB9-KRAS axis regulates lung adenocarcinoma growth in response to cellular energy alterations.
AMPK/SIRT1 Deficiency Drives Adjuvant-Induced Arthritis in Rats by Promoting Glycolysis-Mediated Monocytes Inflammatory Polarization.
AMPK deficiency in smooth muscles causes persistent pulmonary hypertension of the new-born and premature death.
AMPK Activation Is Important for the Preservation of Insulin Sensitivity in Visceral, but Not in Subcutaneous Adipose Tissue of Postnatally Overfed Rat Model of Polycystic Ovary Syndrome.
Angiotensin II receptor type 1 blocker candesartan improves morphine tolerance by reducing morphine‑induced inflammatory response and cellular activation of BV2 cells via the PPARγ/AMPK signaling pathway.
Gut-Flora-Dependent Metabolite Trimethylamine-N-Oxide Promotes Atherosclerosis-Associated Inflammation Responses by Indirect ROS Stimulation and Signaling Involving AMPK and SIRT1.
Ampk Activation Attenuates Her3 Upregulation And Neuregulin-Mediated Rescue of Cell Proliferation in Her2-Overexpressing Breast Cancer Cell Lines Exposed to Lapatinib.
IL11 stimulates ERK/P90RSK to inhibit LKB1/AMPK and activate mTOR initiating a mesenchymal program in stromal, epithelial, and cancer cells.
Autophagy-nutrient sensing pathways in diabetic complications.

Front Physiol. 2022 ;13 928964

AMPKβ isoform expression patterns in various adipocyte models and in relation to body mass index.

Franziska Kopietz, Eva Degerman, Olga Göransson.

  AMP-activated protein kinase (AMPK) activation is considered a useful strategy for the treatment of type 2 diabetes (T2D). It is unclear whether the expression and/or activity of AMPK in adipocytes is dysregulated in obesity. Also, the expression/activity pattern of AMPKβ isoforms, which are targets for AMPK activators, in adipocytes remains elusive. In this study we show that the two AMPKβ isoforms make roughly equal contributions to AMPK activity in primary human and mouse adipocytes, whereas in cultured 3T3-L1 adipocytes of mouse origin and in primary rat adipocytes, β1-associated activity clearly dominates. Additionally, we found that obesity is not associated with changes in AMPK subunit expression or kinase activity in adipocytes isolated from subcutaneous adipose tissue from individuals with various BMI.

Keywords:  AMPKβ; adipocytes; expression; human; kinase activity; obesity

DOI:  https://doi.org/10.3389/fphys.2022.928964
Curr Drug Targets. 2022 ;23(11): 1057-1071

Targeting AMPK Signaling in the Liver: Implications for Obesity and Type 2 Diabetes Mellitus.

Doudou Wang, Lin Yang, Ying Liu.

  Obesity and type 2 diabetes mellitus (T2DM), as common metabolic diseases, are pathologically characterized by overnutrition and insulin resistance (IR), which subsequently lead to glucose and lipid metabolism disorders. The liver, a major metabolic organ of the body, integrates hormone and metabolic signals to regulate the synthesis of lipids and glucose as well as their transport to peripheral tissues, hence playing an essential role in the development of obesity and T2DM. Adenosine 5'-monophosphate-activated protein kinase (AMPK) is a central regulator involved in cellular and organismal metabolism in eukaryotes, which activates processes that produce ATP and diminishes its consumption. In addition, AMPK also regulates mitochondrial homeostasis and promotes autophagy, both of which are associated with the pathogenesis of IR. Therefore, increasing AMPK activity is considered a promising therapeutic strategy to prevent obesity and T2DM. In this review, we summarize the role of hepatic AMPK in obesity and T2DM and the potential of using AMPK activators as therapeutics for metabolic disorders.

Keywords:  AMPK; AMPK activators; hyperglycemia; liver; obesity; type 2 diabetes mellitus

DOI:  https://doi.org/10.2174/1389450123666220429082702
Tissue Cell. 2022 Aug 09. pii: S0040-8166(22)00168-9. [Epub ahead of print]78 101896

Impact of 5'-AMP-activated protein kinase (AMPK) on Epithelial Sodium Channels (ENaCs) in human sperm.

Ayşe Çakır Gündoğdu, Gülnur Take Kaplanoğlu, Sema Ören, Barış Baykal, Cem Korkmaz, Seyhan Gümüşlü, Recep Onur Karabacak.

  Hyperpolarization is associated with decreased intracellular Na+ concentration through the closure of the epithelial Na+ channels (ENaCs) during capacitation. 5'-AMP-activated protein kinase (AMPK) is involved in the regulation of Na+ transport by reducing ENaC-β abundance in the plasma membrane in somatic cells. However, it is not known whether AMPK acts on ENaCs in sperm. The aim of the present study was to analyze the role of AMPK activation in the regulation of ENaC and to examine its relationship with capacitation-associated hyperpolarization of human sperm. Human sperm were treated with AICAR (AMPK activator) in non-capacitating and capacitating conditions. AMPK activity and ENaC-β concentration were evaluated by ELISA. Flow cytometry was used to measure tyrosine phosphorylation, hyperpolarization, intracellular Na+ concentration and acrosome reaction. Immunofluorescence staining was carried out to analyze the distribution of ENaC-β and CD46 in sperm. We found that induction of capacitation triggered AMPK phosphorylation. AMPK activation by AICAR increased tyrosine phosphorylation. AICAR decreased ENaC-β levels, mainly localized at the principal-piece of the flagellum, resulting in lower intracellular Na+ concentration and increased hyperpolarization of the plasma membrane. Altogether, these data provide evidence that AMPK activation is involved in capacitation-associated hyperpolarization by reducing ENaC abundance in human sperm.

Keywords:  5'-AMP-activated protein kinase (AMPK); Capacitation; Epithelial Sodium Channel (ENaC); Human sperm; Hyperpolarization

DOI:  https://doi.org/10.1016/j.tice.2022.101896
J Appl Toxicol. 2022 Aug 23.

PFOS promotes hepatic lipid accumulation and steatosis in high-fat diet mice through AMPK/ACC pathway.

Junyi Ling, Lu Hua, Yi Qin, Tianye Gu, Shengyang Jiang, Jianya Zhao.

  Perfluorooctane sulfonate (PFOS) is a hepatotoxic environmental organic pollutant that can cause aberrant lipid accumulation in the liver. However, the molecular mechanism underlying PFOS-induced hepatic steatosis remains unclear. Our research showed that subchronic PFOS exposure inhibited AMP-activated protein kinase (AMPK) phosphorylation, leading to increased acetyl-CoA carboxylase (ACC) activity, attenuated fatty acid β-oxidation and consequent liver lipid accumulation. We found that 1 mg/kg/day PFOS exposure significantly aggravated steatosis in high-fat diet (HFD)-fed mice, along with reduced AMPK activity. Oil Red O results showed that PFOS exposure caused fat accumulation in HepG2 cells. As predicted, PFOS treatment reduced the level of phosphorylated AMPK in a concentration-dependent manner, leading to subsequent increase in ACC activity and lipid droplet accumulation in HepG2 cells. Treatment with 200 μM AMPK agonist AICAR alleviated PFOS-induced ACC activation and lipid accumulation. In summary, our data highlights a crucial role of AMPK/ACC pathway in PFOS-mediated liver lipid metabolic disorders.

Keywords:  AMPK; PFOS; hepatotoxicity; high-fat diet; lipid metabolism

DOI:  https://doi.org/10.1002/jat.4383
J Cell Sci. 2022 Aug 26. pii: jcs.259609. [Epub ahead of print]

AMPK promotes Arf6 activation in a kinase-independent manner upon energy deprivation.

Kuan-Jung Chen, Jia-Wei Hsu, Fang-Jen S Lee.

  AMP-activated protein kinase (AMPK) is a crucial cellular nutrient and energy sensor that maintains energy homeostasis. AMPK also governs cancer cell invasion and migration by regulating gene expression and activating multiple cellular signaling pathways. ADP-ribosylation factor 6 (Arf6) can be activated via nucleotide exchange by guanine nucleotide exchange factors (GEFs), and its activation also regulates tumor invasion and migration. By studying GEF-mediated Arf6 activation, we elucidated that AMPK functions as a noncanonical GEF for Arf6 in a kinase-independent manner. Moreover, by examining the physiological role of the AMPK-Arf6 axis, we determined that AMPK activates Arf6 upon glucose starvation and 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR) treatment. We further identified the binding motif in the C-terminal regulatory domain of AMPK that is responsible for promoting Arf6 activation and thus inducing cell migration and invasion. These findings reveal a noncanonical role of AMPK in which its C-terminal regulatory domain serves as a GEF for Arf6 during energy deprivation.

Keywords:  ADP-ribosylation factor; Cell invasion; GTPase; Glucose deprivation

DOI:  https://doi.org/10.1242/jcs.259609
Exp Mol Med. 2022 Aug 23.

AMPK suppresses Th2 cell responses by repressing mTORC2.

Mahesh Pandit, Maheshwor Timilshina, Ye Gu, Suman Acharya, Yeonseok Chung, Sang-Uk Seo, Jae-Hoon Chang.

Allergic inflammation is a T helper 2 (Th2) cell-driven pathophysiological phenomenon, but the mechanism by which the metabolic cascade affects Th2 cell differentiation remains unclear. In this study, we investigated the roles of AMP-activated protein kinase (AMPK) and intracellular energy sensors in Th2 cell differentiation and the pathogenesis of allergic inflammation. Accordingly, T-cell-specific AMPK or Sirtuin 1 (Sirt1)-knockout mice were subjected to allergic inflammation, and their Th2 cell responses were investigated. The results demonstrated that inducing allergic inflammation in AMPK- and Sirt1-knockout mice increased Th2 cell responses and exacerbated allergic phenotypes. Furthermore, treatment with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an activator of AMPK, ameliorated allergic inflammation in mice. Mechanistically, our findings revealed that AMPK repressed mechanistic target of rapamycin complex 2 (mTORC2), which downregulated the expression of suppressor of cytokine signaling 5 (SOCS5) in CD4+ T cells. In addition, the loss of AMPK signaling reduced SOCS5 expression and increased interleukin-4-STAT6-GATA3 axis-mediated Th2 cell differentiation. Finally, the T-cell-specific deletion of Rictor, a member of mTORC2, in Sirt1T-KO mice led to the reversal of allergic exacerbation to the level in control mice. Overall, our findings suggest that AMPK in CD4+ T cells inhibits the differentiation of Th2 cells by repressing mTORC2 and thus serves as a potential target for Th2 cell-associated diseases.

DOI: https://doi.org/10.1038/s12276-022-00832-x
Development. 2022 Oct 15. pii: dev200955. [Epub ahead of print]149(20):

PHLPP1 regulates CFTR activity and lumen expansion through AMPK.

Viola H Lobert, Maren L Skardal, Lene Malerød, Julia E Simensen, Hermine A Algra, Aram N Andersen, Thomas Fleischer, Hilde A Enserink, Knut Liestøl, Joan K Heath, Tor Erik Rusten, Harald A Stenmark.

  Complex organ development depends on single lumen formation and its expansion during tubulogenesis. This can be achieved by correct mitotic spindle orientation during cell division, combined with luminal fluid filling that generates hydrostatic pressure. Using a human 3D cell culture model, we have identified two regulators of these processes. We find that pleckstrin homology leucine-rich repeat protein phosphatase (PHLPP) 2 regulates mitotic spindle orientation, and thereby midbody positioning and maintenance of a single lumen. Silencing the sole PHLPP family phosphatase in Drosophila melanogaster, phlpp, resulted in defective spindle orientation in Drosophila neuroblasts. Importantly, cystic fibrosis transmembrane conductance regulator (CFTR) is the main channel regulating fluid transport in this system, stimulated by phosphorylation by protein kinase A and inhibited by the AMP-activated protein kinase AMPK. During lumen expansion, CFTR remains open through the action of PHLPP1, which stops activated AMPK from inhibiting ion transport through CFTR. In the absence of PHLPP1, the restraint on AMPK activity is lost and this tips the balance in the favour of channel closing, resulting in the lack of lumen expansion and accumulation of mucus.

Keywords:  3D culture; AMPK; CFTR; Epithelial; Lumenogenesis; PHLPP

DOI:  https://doi.org/10.1242/dev.200955
Food Sci Biotechnol. 2022 Sep;31(10): 1289-1297

Gryllus bimaculatus extract ameliorates high-fat diet-induced hyperglycemia and hyperlipidemia by inhibiting hepatic lipogenesis through AMPK activation.

Kyong Kim, Eun-Young Park, Dong Jae Baek, Yoon Sin Oh.

  Insect-based food is increasingly used and is a sustainable protein source provided by eco-friendly breeding respecting the animal welfare. The cricket Gryllus bimaculatus is an approved edible insect. In this paper, the effects of G. bimaculatus extracts (AE-GBE) on hepatic insulin resistance and the underlying mechanisms were investigated in high fat diet (HFD)-fed C57BL/6J mice. Mice were fed HFD for 6 weeks and some were concomitantly given AE-GBE orally (100 mg/kg/day). AE-GBE significantly improved glucose tolerance and insulin sensitivity by attenuating hepatic lipid accumulation measured by the reduced serum and hepatic lipid contents. Moreover, AE-GBE significantly downregulated the expression of hepatic lipogenesis-related genes and activated the AMPK signaling pathway. Therefore, AE-GBE might improve fatty liver and glucose metabolism disorders as well as insulin resistance by inhibiting the expression of proteins involved in hepatic fatty acid synthesis through AMPK activation.
Supplementary Information: The online version contains supplementary material available at 10.1007/s10068-022-01117-9.

Keywords:  AMP-activated protein kinase; Gryllus bimaculatus; Hepatic insulin resistance; Lipogenesis; Nonalcoholic fatty liver disease

DOI:  https://doi.org/10.1007/s10068-022-01117-9
Free Radic Biol Med. 2022 Aug 20. pii: S0891-5849(22)00556-1. [Epub ahead of print]

Cladrin alleviates dexamethasone-induced apoptosis of osteoblasts and promotes bone formation through autophagy induction via AMPK/mTOR signaling.

Reena Rai, Krishna Bhan Singh, Sonu Khanka, Rakesh Maurya, Divya Singh.

  Glucocorticoid-induced osteoporosis (GIOP) is a common clinical consequence that arises due to the extensive usage of glucocorticoids. Cladrin (Clad), a methoxylated isoflavone has been reported to have a bone protecting effect by enhancing osteoblast proliferation and differentiation. However, its consequences on GIOP are not reported yet. This study investigates whether Clad protects against the deleterious effects of Dexamethasone (Dex) on osteoblast and bone. Mice calvarial osteoblasts were treated with Clad and then exposed to Dex to study the effect on osteoblast differentiation, proliferation, and survival. Further, GIOP mice were treated with Clad (5 and 10 mg/kg) doses along with reference standard alendronate (ALN 3 mg/kg) for evaluation of bone protecting effect of Clad. We analyzed bone and vertebral microarchitecture, mechanical strength, and biochemical parameters. We observed that Clad at 10 nM concentration mitigated Dex-induced cytotoxicity and defend osteoblasts against apoptosis. Subsequent results demonstrate that Clad suppressed apoptosis of osteoblast in the presence of Dex by enhancing autophagy in a way that was reliant on the AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) pathway. Furthermore, micro-CT scanning, eco MRI results, and serum CTX levels revealed that 12 weeks of Clad treatment prevented bone loss and preserved trabecular bone mass in GIOP animals. We also observed that Clad treated osteoblasts had a lower rate of apoptosis and a greater LC3-II/LC3-I ratio than the Dex group. Our findings show that Clad can protect osteoblasts against glucocorticoids by inducing autophagy via the AMPK/mTOR pathway.

Keywords:  Autophagy; Cladrin; Dexamethasone; Glucocorticoids; Osteoblast

DOI:  https://doi.org/10.1016/j.freeradbiomed.2022.08.028
Diabetes. 2022 Aug 24. pii: db220205. [Epub ahead of print]

miR-130b/301b is a Negative Regulator of Beige Adipogenesis and Energy Metabolism in vitro and in vivo.

Wenyi Luo, Youngsil Kim, Mary Ellen Jensen, Oana Herlea-Pana, Weidong Wang, Michael C Rudolph, Jacob E Friedman, Steven D Chernausek, Shaoning Jiang.

Thermogenic brown or beige adipocytes dissipate energy in the form of heat and thereby counteract obesity and related metabolic complications. The microRNA cluster, miR-130b/301b, is highly expressed in adipose tissues and has been implicated in metabolic diseases as a post-transcriptional regulator of mitochondrial biogenesis and lipid metabolism. We investigated the roles of miR-130b/301b in regulating beige adipogenesis in vivo and in vitro. miR-130b/301b declined in adipose progenitor cells during beige adipogenesis, while forced overexpression of miR-130b-3p or miR-301b-3p suppressed uncoupling protein 1 (UCP1) and mitochondrial respiration, suggesting a decline in miR-130b-3p or miR-301b-3p is required for adipocyte precursors to develop the beige phenotype. Mechanistically, miR-130b/301b directly targeted AMP-activated protein kinase (AMPKα1) and suppressed peroxisome proliferator-activated receptor gamma coactivator 1-alpha (Pgc-1α), key regulators of brown adipogenesis and mitochondrial biogenesis. Mice lacking the miR-130b/301b microRNA cluster showed reduced visceral adiposity and less weight gain. miR-130b/301b null mice exhibited improved glucose tolerance, increased UCP1 and AMPK activation in subcutaneous fat (iWAT), and increased response to cold-induced energy expenditure. Together, these data identify the miR-130b/301b cluster as a new regulator that suppresses beige adipogenesis involving PGC-1α and AMPK signaling in iWAT and is therefore a potential therapeutic target against obesity and related metabolic disorders.

DOI: https://doi.org/10.2337/db22-0205
Cell Rep. 2022 Aug 23. pii: S2211-1247(22)01027-0. [Epub ahead of print]40(8): 111210

The AMPK-HOXB9-KRAS axis regulates lung adenocarcinoma growth in response to cellular energy alterations.

Tianzhuo Wang, Huiying Guo, Qianchen Li, Weijie Wu, Miao Yu, Lei Zhang, Cuicui Li, Jiagui Song, Zhenbin Wang, Jing Zhang, Yan Tang, Lei Kang, Hongquan Zhang, Jun Zhan.

  HOXB9 is an important transcription factor associated with unfavorable outcomes in patients with lung adenocarcinoma (LUAD). However, its degradation mechanism remains unclear. Here, we show that HOXB9 is a substrate of AMP kinase alpha (AMPKα). AMPK mediates HOXB9 T133 phosphorylation and downregulates the level of HOXB9 in mice and LUAD cells. Mechanistically, phosphorylated HOXB9 promoted E3 ligase Praja2-mediated HOXB9 degradation. Blocking HOXB9 phosphorylation by depleting AMPKα1/2 or employing the HOXB9 T133A mutant promoted tumor cell growth in cell culture and mouse xenografts via upregulation of HOXB9 and KRAS that is herein identified as a target of HOXB9. Clinically, AMPK activation levels in LUAD samples were positively correlated with pHOXB9 levels; higher pHOXB9 levels were associated with better survival of patients with LUAD. We thus present a HOXB9 degradation mechanism and demonstrate an AMPK-HOXB9-KRAS axis linking glucose-level-regulated AMPK activation to HOXB9 stability and KRAS gene expression, ultimately controlling LUAD progression.

Keywords:  AMPK; CP: Cancer; CP: Metabolism; HOXB9 T133 phosphorylation; KRAS; LUAD; Praja2; metformin; ubiquitin-mediated degradation

DOI:  https://doi.org/10.1016/j.celrep.2022.111210
J Inflamm Res. 2022 ;15 4663-4675

AMPK/SIRT1 Deficiency Drives Adjuvant-Induced Arthritis in Rats by Promoting Glycolysis-Mediated Monocytes Inflammatory Polarization.

Dan-Dan Wang, Chi-Yi He, Yi-Jin Wu, Liang Xu, Chao Shi, Opeyemi Joshua Olatunji, Jian Zuo, Cong-Lan Ji.

   Background: Exact roles of many metabolic regulators in rheumatoid arthritis (RA) are to be clarified. This study aimed to further characterize the impacts of silent information regulator 1 (SIRT1) status changes on this disease.
Methods: Fluctuation pattern of SIRT1 expression in adjuvant-induced arthritis (AIA) rats was monitored using periodically collected white blood cells. Another bath of AIA rats were treated by SIRT1 agonist resveratrol. Blood from these rats was used to separate monocytes and plasma, which were subjected to polymerase chain reaction (PCR), enzyme linked immunosorbent assay (ELISA), and biochemical analyses. Clinical implication of SIRT1 activation was verified by treating AIA rat monocytes with SIRT1 agonist and overexpression vector in vitro.
Results: SIRT1 deficiency occurred in AIA rats, which was accompanied with down-regulation of interleukin 10 (IL-10) and arginase-1 (ARG-1). Resveratrol eased oxidative stress and increased IL-10 production in vivo. Results of ELISA analysis demonstrated that resveratrol attenuated AIA severity in rats. Furthermore, it restored the altered levels of triglyceride, lactate and pyruvate in blood. Resveratrol promoted IL-10 production, and suppressed glycolysis of AIA monocytes cultured in vitro. SIRT1 overexpression similarly reshaped differentiation profile of AIA monocytes, evidenced by changes in metabolism indicators, IL-10 production and AMP-activated protein kinase (AMPK) pathway status. Although overexpressing SIRT1 in normal cells did not affect glycolysis significantly, it attenuated AMPK antagonist-caused abnormality.
Conclusion: SIRT1 deficiency is implicated in AIA-related immune abnormality and metabolism alteration. Activating this signaling with resveratrol would impair the inflammatory polarization of monocytes, and consequently ease the severity of RA.

Keywords:  inflammation; metabolic reprogramming; monocytes; resveratrol; rheumatoid arthritis

DOI:  https://doi.org/10.2147/JIR.S378090
Nat Commun. 2022 Aug 26. 13(1): 5034

AMPK deficiency in smooth muscles causes persistent pulmonary hypertension of the new-born and premature death.

Javier Moral-Sanz, Sophronia A Lewis, Sandy MacMillan, Marco Meloni, Heather McClafferty, Benoit Viollet, Marc Foretz, Jorge Del-Pozo, A Mark Evans.

AMPK has been reported to facilitate hypoxic pulmonary vasoconstriction but, paradoxically, its deficiency precipitates pulmonary hypertension. Here we show that AMPK-α1/α2 deficiency in smooth muscles promotes persistent pulmonary hypertension of the new-born. Accordingly, dual AMPK-α1/α2 deletion in smooth muscles causes premature death of mice after birth, associated with increased muscularisation and remodeling throughout the pulmonary arterial tree, reduced alveolar numbers and alveolar membrane thickening, but with no oedema. Spectral Doppler ultrasound indicates pulmonary hypertension and attenuated hypoxic pulmonary vasoconstriction. Age-dependent right ventricular pressure elevation, dilation and reduced cardiac output was also evident. KV1.5 potassium currents of pulmonary arterial myocytes were markedly smaller under normoxia, which is known to facilitate pulmonary hypertension. Mitochondrial fragmentation and reactive oxygen species accumulation was also evident. Importantly, there was no evidence of systemic vasculopathy or hypertension in these mice. Moreover, hypoxic pulmonary vasoconstriction was attenuated by AMPK-α1 or AMPK-α2 deletion without triggering pulmonary hypertension.

DOI: https://doi.org/10.1038/s41467-022-32568-7
Int J Mol Sci. 2022 Aug 11. pii: 8942. [Epub ahead of print]23(16):

AMPK Activation Is Important for the Preservation of Insulin Sensitivity in Visceral, but Not in Subcutaneous Adipose Tissue of Postnatally Overfed Rat Model of Polycystic Ovary Syndrome.

Bojana Mićić, Ana Teofilović, Ana Djordjevic, Nataša Veličković, Djuro Macut, Danijela Vojnović Milutinović.

  Polycystic ovary syndrome (PCOS) is a well-known reproductive syndrome usually associated with obesity, insulin resistance, and hyperinsulinemia. Although the first signs of PCOS begin early in adolescence, it is underexplored whether peripubertal obesity predisposes women to PCOS metabolic disturbances. To highlight that, we examined the impact of postnatal overfeeding-induced obesity, achieved by litter size reduction during the suckling period, on metabolic disturbances associated with visceral and subcutaneous adipose tissue (VAT and SAT) function in the 5α-dihydrotestosterone (5α-DHT)-induced animal model of PCOS. We analyzed markers of insulin signaling, lipid metabolism, and energy sensing in the VAT and SAT. Our results showed that postnatally overfed DHT-treated Wistar rats had increased VAT mass with hypertrophic adipocytes, together with hyperinsulinemia and increased HOMA index. In the VAT of these animals, insulin signaling remained unchanged while lipogenic markers decreased, which was accompanied by increased AMPK activation. In the SAT of the same animals, markers of lipogenesis and lipolysis increased, while the activity of AMPK decreased. Taken together, obtained results showed that postnatal overfeeding predisposes development of PCOS systemic insulin resistance, most likely as a result of worsened metabolic function of SAT, while VAT preserved its tissue insulin sensitivity through increased activity of AMPK.

Keywords:  5α-dihydrotestosterone; AMP-activated kinase; early postnatal overfeeding; insulin resistance; lipogenesis; lipolysis; obesity; polycystic ovary syndrome; subcutaneous adipose tissue; visceral adipose tissue

DOI:  https://doi.org/10.3390/ijms23168942
Mol Med Rep. 2022 Oct;pii: 318. [Epub ahead of print]26(4):

Angiotensin II receptor type 1 blocker candesartan improves morphine tolerance by reducing morphine‑induced inflammatory response and cellular activation of BV2 cells via the PPARγ/AMPK signaling pathway.

Wenxin Zhao, Feiyan Shen, Jixiang Yao, Shanshan Su, Zhongmin Zhao.

  Morphine is the most common drug of choice in clinical pain management; however, morphine tolerance presents a significant clinical challenge. The pathogenesis of morphine tolerance is known to be closely associated with angiotensin II receptor type 1 (AT1R) in microglia. As an AT1R antagonist, candesartan may serve an important role in regulating morphine tolerance. Therefore, the present study aimed to investigate the role of candesartan in morphine tolerance, and to explore the underlying mechanism. To meet this aim, BV2 microglial cells were treated with morphine or candesartan alone, or as a combination, and the expression levels of AT1R in BV2 cells were detected by reverse transcription‑quantitative PCR (RT‑qPCR) and western blotting. The levels of the inflammatory cytokines tumor necrosis factor‑α, interleukin (IL)‑1β and IL‑6 were subsequently detected by ELISA and western blotting. In addition, immunofluorescence analysis, western blotting and RT‑qPCR were used to detect the expression levels of the BV2 cell activation marker, ionized calcium‑binding adaptor molecule 1 (IBA‑1). Western blotting was also used to detect the expression levels of peroxisome proliferator‑activated receptor‑γ/AMP‑activated protein kinase (PPARγ/AMPK) signaling pathway‑associated proteins. Finally, the cells were treated with the PPARγ antagonist GW9662 and the AMPK inhibitor compound C to further explore the mechanism underlying the effects of candesartan on improving morphine tolerance. The expression levels of AT1R were revealed to be significantly increased following morphine induction; however, candesartan treatment inhibited the expression levels of AT1R, the levels of inflammatory cytokines and the protein expression levels of IBA‑1 in morphine‑induced BV2 cells in a dose‑dependent manner. These processes may be associated with activation of the PPARγ/AMPK signaling pathway. Taken together, the present study revealed that treatment with candesartan reduced morphine‑induced inflammatory response and cellular activation of BV2 cells via PPARγ/AMPK signaling.

Keywords:  BV2 cells; PPARγ/AMPK signaling; angiotensin II receptor type 1; candesartan; inflammation; morphine tolerance

DOI:  https://doi.org/10.3892/mmr.2022.12834
Nutrients. 2022 Aug 15. pii: 3338. [Epub ahead of print]14(16):

Gut-Flora-Dependent Metabolite Trimethylamine-N-Oxide Promotes Atherosclerosis-Associated Inflammation Responses by Indirect ROS Stimulation and Signaling Involving AMPK and SIRT1.

Sa Zhou, Jiamin Xue, Jingbo Shan, Yingxiang Hong, Wenkang Zhu, Zhiyan Nie, Yujie Zhang, Nanxi Ji, Xuegang Luo, Tongcun Zhang, Wenjian Ma.

  Trimethylamine-N-oxide (TMAO), a gut-microbiota-dependent metabolite after ingesting dietary choline, has been identified as a novel risk factor for atherosclerosis through inducing vascular inflammation. However, the underlying molecular mechanism is poorly understood. Using an in vitro vascular cellular model, we found that the TMAO-induced inflammation responses were correlated with an elevation of ROS levels and downregulation of SIRT1 expression in VSMCs and HUVECs. The overexpression of SIRT1 could abrogate both the stimulation of ROS and inflammation. Further studies revealed that AMPK was also suppressed by TMAO and was a mediator upstream of SIRT1. Activation of AMPK by AICAR could reduce TMAO-induced ROS and inflammation. Moreover, the GSH precursor NAC could attenuate TMAO-induced inflammation. In vivo studies with mice models also showed that choline-induced production of TMAO and the associated glycolipid metabolic changes leading to atherosclerosis could be relieved by NAC and a probiotic LP8198. Collectively, the present study revealed an unrecognized mechanistic link between TMAO and atherosclerosis risk, and probiotics ameliorated TMAO-induced atherosclerosis through affecting the gut microbiota. Consistent with previous studies, our data confirmed that TMAO could stimulate inflammation by modulating cellular ROS levels. However, this was not due to direct cytotoxicity but through complex signaling pathways involving AMPK and SIRT1.

Keywords:  ROS; TMAO; atherosclerosis; choline; gut microbiota; inflammation

DOI:  https://doi.org/10.3390/nu14163338
Biochem Pharmacol. 2022 Aug 22. pii: S0006-2952(22)00322-7. [Epub ahead of print] 115228

Ampk Activation Attenuates Her3 Upregulation And Neuregulin-Mediated Rescue of Cell Proliferation in Her2-Overexpressing Breast Cancer Cell Lines Exposed to Lapatinib.

Barbara Buccinnà, Cristina Ramondetti, Marco Piccinini.

  Lapatinib is a highly selective reversible inhibitor of the tyrosine kinase domains of HER2 and EGFR, approved for the treatment of advanced stage HER2-overexpressing breast cancers. Although targeted therapy with lapatinib provides initial clinical advantage, cancer cells' adaptive responses can overcome the inhibitory effects of lapatinib. HER3 upregulation and autocrine induction of HER3 ligand neuregulin-1 (NRG), have been implicated in the restoration of AKT and ERK1/2 activity and rescue of cell proliferation. In this study we evaluated the effects of lapatinib alone and in combination with AMPK activator GSK-621 in HER2-overexpressing breast cancer cell lines SKBR3 and BT474. Our results show that in cells exposed to lapatinib and GSK-621 in combination, lapatinib-mediated HER3 upregulation was reduced and reactivation of AKT and ERK1/2 kinases was prevented. The two drugs in combination decreased cell viability in a synergistic manner and greatly reduced the ability of NRG to rescue cell proliferation. Finally, we provide evidence that in cells exposed to lapatinib and GSK-621 in combination the establishment of a transcriptionally permissive chromatin structure at the HER3 promoter is hampered. The results of this study highlight a potential role for AMPK activation in counteracting lapatinib-induced adaptive responses of HER2-overexpressing breast cancer cells.

Keywords:  AMPK; GSK-621; HER3; breast cancer; lapatinib; neuregulin

DOI:  https://doi.org/10.1016/j.bcp.2022.115228
iScience. 2022 Aug 19. 25(8): 104806

IL11 stimulates ERK/P90RSK to inhibit LKB1/AMPK and activate mTOR initiating a mesenchymal program in stromal, epithelial, and cancer cells.

Anissa A Widjaja, Sivakumar Viswanathan, Joyce Goh Wei Ting, Jessie Tan, Shamini G Shekeran, David Carling, Wei-Wen Lim, Stuart A Cook.

  IL11 initiates fibroblast activation but also causes epithelial cell dysfunction. The mechanisms underlying these processes are not known. We report that IL11-stimulated ERK/P90RSK activity causes the phosphorylation of LKB1 at S325 and S428, leading to its inactivation. This inhibits AMPK and activates mTOR across cell types. In stromal cells, IL11-stimulated ERK activity inhibits LKB1/AMPK which is associated with mTOR activation, ⍺SMA expression, and myofibroblast transformation. In hepatocytes and epithelial cells, IL11/ERK activity inhibits LKB1/AMPK leading to mTOR activation, SNAI1 expression, and cell dysfunction. Across cells, IL11-induced phenotypes were inhibited by metformin stimulated AMPK activation. In mice, genetic or pharmacologic manipulation of IL11 activity revealed a critical role of IL11/ERK signaling for LKB1/AMPK inhibition and mTOR activation in fatty liver disease. These data identify the IL11/mTOR axis as a signaling commonality in stromal, epithelial, and cancer cells and reveal a shared IL11-driven mesenchymal program across cell types.

Keywords:  Cell biology; Functional aspects of cell biology

DOI:  https://doi.org/10.1016/j.isci.2022.104806
Pharmacol Res. 2022 Aug 18. pii: S1043-6618(22)00353-X. [Epub ahead of print] 106408

Autophagy-nutrient sensing pathways in diabetic complications.

Urvi M Parmar, Manjiri P Jalgaonkar, Yogesh A Kulkarni, Manisha J Oza.

  The incidence of diabetes has been increasing in recent decades which is affecting the population of both, developed and developing countries. Diabetes is associated with micro and macrovascular complications which predominantly result from hyperglycemia and disrupted metabolic pathways. Persistent hyperglycemia leads to increased reactive oxygen species (ROS) generation, formation of misfolded and abnormal proteins, and disruption of normal cellular functioning. The inability to maintain metabolic homeostasis under excessive energy and nutrient input, which induces insulin resistance, is a crucial feature during the transition from obesity to diabetes. According to various study reports, redox alterations, intracellular stress and chronic inflammation responses have all been linked to dysregulated energy metabolism and insulin resistance. Autophagy has been considered a cleansing mechanism to prevent these anomalies and restore cellular homeostasis. However, disrupted autophagy has been linked to the pathogenesis of metabolic disorders such as obesity and diabetes. Recent studies have reported that the regulation of autophagy has a beneficial role against these conditions. When there is plenty of food, nutrient-sensing pathways activate anabolism and storage, but the shortage of food activates homeostatic mechanisms like autophagy, which mobilises internal stockpiles. These nutrient-sensing pathways are well conserved in eukaryotes and are involved in the regulation of autophagy which includes SIRT1, mTOR and AMPK. The current review focuses on the role of SIRT1, mTOR and AMPK in regulating autophagy and suggests autophagy along with these nutrient-sensing pathways as potential therapeutic targets in reducing the progression of various diabetic complications.

Keywords:  AMPK; SIRT1; diabetic cardiomyopathy; diabetic nephropathy; diabetic neuropathy; diabetic retinopathy; mTOR

DOI:  https://doi.org/10.1016/j.phrs.2022.106408