bims-amsmem 2023-01-08 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2023–01–08
thirteen papers selected by
Dipsikha Biswas, Københavns Universitet

Exercise preserves physical fitness during aging through AMPK and mitochondrial dynamics.
Editorial: Untangling energy metabolism in skeletal muscle: From physiology to pharmacology.
Mechanism of autophagy induced by activation of the AMPK/ERK/mTOR signaling pathway after TRIM22-mediated DENV-2 infection of HUVECs.
Canagliflozin promotes osteoblastic MC3T3-E1 differentiation via AMPK/RUNX2 and improves bone microarchitecture in type 2 diabetic mice.
AMPK regulates DNA methylation of PGC-1α and myogenic differentiation in human mesenchymal stem cells.
Novel role of AMPK in cocaine reinforcement via regulating CRTC1.
Vitamin D and lactoferrin attenuate stress-induced colitis in Wistar rats via enhancing AMPK expression with inhibiting mTOR-STAT3 signaling and modulating autophagy.
Fumarate hydratase inhibits non-small cell lung cancer metastasis via inactivation of AMPK and upregulation of DAB2.
LOX-1 attenuates high glucose-induced autophagy via AMPK/HNF4α signaling in HLSECs.
AMPK integrates metabolite and kinase-based immunometabolic control in macrophages.
CircZSWIM6 mediates dysregulation of ECM and energy homeostasis in ageing chondrocytes through RPS14 post-translational modification.
Calycosin induces autophagy and apoptosis via Sestrin2/AMPK/mTOR in human papillary thyroid cancer cells.
Metformin protects trabecular meshwork against oxidative injury via activating integrin/ROCK signals.

Proc Natl Acad Sci U S A. 2023 Jan 10. 120(2): e2204750120

Exercise preserves physical fitness during aging through AMPK and mitochondrial dynamics.

Juliane Cruz Campos, Luiz Henrique Marchesi Bozi, Barbara Krum, Luiz Roberto Grassmann Bechara, Nikolas Dresch Ferreira, Gabriel Santos Arini, Rudá Prestes Albuquerque, Annika Traa, Takafumi Ogawa, Alexander M van der Bliek, Afshin Beheshti, Edward T Chouchani, Jeremy M Van Raamsdonk, T Keith Blackwell, Julio Cesar Batista Ferreira.

  Exercise is a nonpharmacological intervention that improves health during aging and a valuable tool in the diagnostics of aging-related diseases. In muscle, exercise transiently alters mitochondrial functionality and metabolism. Mitochondrial fission and fusion are critical effectors of mitochondrial plasticity, which allows a fine-tuned regulation of organelle connectiveness, size, and function. Here we have investigated the role of mitochondrial dynamics during exercise in the model organism Caenorhabditis elegans. We show that in body-wall muscle, a single exercise session induces a cycle of mitochondrial fragmentation followed by fusion after a recovery period, and that daily exercise sessions delay the mitochondrial fragmentation and physical fitness decline that occur with aging. Maintenance of proper mitochondrial dynamics is essential for physical fitness, its enhancement by exercise training, and exercise-induced remodeling of the proteome. Surprisingly, among the long-lived genotypes we analyzed (isp-1,nuo-6, daf-2, eat-2, and CA-AAK-2), constitutive activation of AMP-activated protein kinase (AMPK) uniquely preserves physical fitness during aging, a benefit that is abolished by impairment of mitochondrial fission or fusion. AMPK is also required for physical fitness to be enhanced by exercise, with our findings together suggesting that exercise may enhance muscle function through AMPK regulation of mitochondrial dynamics. Our results indicate that mitochondrial connectivity and the mitochondrial dynamics cycle are essential for maintaining physical fitness and exercise responsiveness during aging and suggest that AMPK activation may recapitulate some exercise benefits. Targeting mechanisms to optimize mitochondrial fission and fusion, as well as AMPK activation, may represent promising strategies for promoting muscle function during aging.

Keywords:  C. elegans; aging; exercise; mitochondrial fission; mitochondrial fusion

DOI:  https://doi.org/10.1073/pnas.2204750120
Front Physiol. 2022 ;13 1113860

Editorial: Untangling energy metabolism in skeletal muscle: From physiology to pharmacology.

Sergej Pirkmajer, Pablo M Garcia-Roves, Arild C Rustan, Alexander V Chibalin.



Keywords:  AMPK; angiotensin-converting enzyme (ACE); double-stranded RNA-activated protein kinase; energy metabolism; metformin; myosin; obesity; skeletal muscle

DOI:  https://doi.org/10.3389/fphys.2022.1113860
Virol J. 2022 Dec 31. 19(1): 228

Mechanism of autophagy induced by activation of the AMPK/ERK/mTOR signaling pathway after TRIM22-mediated DENV-2 infection of HUVECs.

Ning Wu, Xiaoqin Gou, Pan Hu, Yao Chen, Jinzhong Ji, Yuanying Wang, Li Zuo.

   BACKGROUND: Dengue virus type 2 (DENV-2) was used to infect primary human umbilical vein endothelial cells (HUVECs) to examine autophagy induced by activation of the adenosine monophosphate-activated protein kinase (AMPK)/extracellular signal-regulated kinase (ERK)/mammalian target of rapamycin (mTOR) signaling pathway following tripartite motif-containing 22 (TRIM22)-mediated DENV-2 infection to further reveal the underlying pathogenic mechanism of DENV-2 infection.
METHODS: Quantitative real-time polymerase chain reaction (qRT-PCR) was used to screen putative interference targets of TRIM22 and determine the knockdown efficiency. The effect of TRIM22 knockdown on HUVEC proliferation was determined using the CCK8 assay. Following TRIM22 knockdown, transmission electron microscopy (TEM) was used to determine the ultrastructure of HUVEC autophagosomes and expression of HUVEC autophagy and AMPK pathway-related genes were measured by qRT-PCR. Moreover, HUVEC autophagy and AMPK pathway-related protein expression levels were determined by western blot analysis. Cell cycle and apoptosis were assessed by flow cytometry (FCM) and the autophagosome structure of the HUVECs was observed by TEM.
RESULTS: Western blot results indicated that TRIM22 protein expression levels increased significantly 36 h after DENV-2 infection, which was consistent with the proteomics prediction. The CCK8 assay revealed that HUVEC proliferation was reduced following TRIM22 knockdown (P < 0.001). The TEM results indicated that HUVEC autolysosomes increased and autophagy was inhibited after TRIM22 knockdown. The qRT-PCR results revealed that after TRIM22 knockdown, the expression levels of antithymocyte globulin 7 (ATG7), antithymocyte globulin 5 (ATG5), Beclin1, ERK, and mTOR genes decreased (P < 0.01); however, the expression of AMPK genes (P < 0.05) and P62 genes (P < 0.001) increased. FCM revealed that following TRIM22 knockdown, the percentage of HUVECs in the G2 phase increased (P < 0.001) along with cell apoptosis. The effect of TRIM22 overexpression on HUVEC autophagy induced by DENV-2 infection and AMPK pathways decreased after adding an autophagy inhibitor.
CONCLUSIONS: In HUVECs, TRIM22 protein positively regulates autophagy and may affect autophagy through the AMPK/ERK/mTOR signaling pathway. Autophagy is induced by activation of the AMPK/ERK/mTOR signaling pathway following TRIM22-mediated DENV-2 infection of HUVECs.

Keywords:  AMPK/ERK/mTOR signaling pathway; Autophagy; DENV-2; TRIM22

DOI:  https://doi.org/10.1186/s12985-022-01932-w
Front Endocrinol (Lausanne). 2022 ;13 1081039

Canagliflozin promotes osteoblastic MC3T3-E1 differentiation via AMPK/RUNX2 and improves bone microarchitecture in type 2 diabetic mice.

Peiyang Song, Tianyi Chen, Shunli Rui, Xiaodong Duan, Bo Deng, David G Armstrong, Yu Ma, Wuquan Deng.

  Individuals with type 2 diabetes mellitus (T2DM) have an increased risk of bone metabolic disorders and bone fracture due to disease progression and clinical treatment. The effect of sodium-glucose cotransporter 2 (SGLT2) inhibitors, now greatly prescribed for the treatment of T2DM, on bone metabolism is not clear. This study aimed to explore the possible influence of bone metabolic disorder and the underlying mechanism through a comparison of three different SGLT2 inhibitors (canagliflozin, dapagliflozin, and empagliflozin) in the treatment of type 2 diabetic mice. For the in vivo experiments, four groups (DM, DM+Cana, DM+Dapa, and DM+Empa) were established using micro-CT to detect the bone microarchitecture and bone-related parameters. The study results indicated that canagliflozin, but not dapagliflozin or empagliflozin, increased bone mineral density (p<0.05) and improved bone microarchitecture in type 2 diabetic mice. Furthermore, canagliflozin promoted osteoblast differentiation at a concentration of 5 μM under high glucose concentration (HG). Phosphorylated adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) α (Thr172) has been confirmed to activate run-related transcription factor-2 (RUNX2) to perform this function. This effect can be partially reversed by the AMPK inhibitor dorsomorphin (compound C) and strengthened by the AMPK activator acadesine (AICAR) in vitro. The level trend of RUNX2 and p-AMPK in vivo were consistent with those in vitro. This study suggested that canagliflozin played a beneficial role in bone metabolism in type 2 diabetic mice compared with dapagliflozin and empagliflozin. It provides some theoretical support for the chosen drugs, especially for patients with osteoporosis or a high risk of fracture.

Keywords:  AMPK/RUNX2; SGLT2 inhibitors; bone metabolism; canagliflozin; type 2 diabetes mellitus

DOI:  https://doi.org/10.3389/fendo.2022.1081039
Stem Cells Dev. 2023 Jan 03.

AMPK regulates DNA methylation of PGC-1α and myogenic differentiation in human mesenchymal stem cells.

Jianbo Wu, Shelly Gulati, April M Teague, Youngsil Kim, Jeanie Tryggestad, Shaoning Jiang.

Adverse intrauterine environments can cause persistent changes in epigenetic profiles of stem cells, increasing susceptibility of the offspring to developing metabolic diseases later in life. Effective approaches to restore the epigenetic landscape and function of stem cells remain to be determined. Here we investigated the effects of pharmaceutical activation of AMPK, an essential regulator of energy metabolism, on mitochondrial programming of Wharton's Jelly mesenchymal stem cells (WJ-MSCs) from women with diabetes during pregnancy. Induction of myogenic differentiation of WJ-MSCs was associated with increased PGC-1α expression and mitochondrial DNA abundance. Inhibition of DNA methylation by 5 Azacytidine significantly increased PGC-1α expression and mitochondrial DNA abundance in WJ-MSCs, which were abolished by AMPK inhibitor Compound C (CC), suggesting an AMPK-dependent role of DNA demethylation in regulating mitochondrial biogenesis in WJ-MSCs. Further, activation of AMPK in diabetic WJ-MSCs by AICAR or metformin decreased the level of PGC-1α promoter methylation and increased PGC-1α expression. Notably, decreased PGC-1α promoter methylation by transient treatment of AMPK activators persisted following myogenic differentiation. This was associated with enhanced myogenic differentiation capacity of human WJ-MSCs and increased mitochondrial function. Taken together, our findings revealed an important role for AMPK activators in epigenetic regulation of mitochondrial biogenesis and myogenesis in WJ-MSCs, which could lead to potential therapeutics for preventing fetal mitochondrial programming and long-term adverse outcome in offspring of women with diabetes during pregnancy.

DOI: https://doi.org/10.1089/scd.2022.0226
Transl Psychiatry. 2022 Dec 31. 12(1): 530

Novel role of AMPK in cocaine reinforcement via regulating CRTC1.

Xiao-Xing Liu, Fang-Lin Liu, Xin Li, Tang-Sheng Lu, Yi-Xiao Luo, Min Jian, Kai Yuan, Shi-Qiu Meng, Yan-Ping Bao, Jie Shi, Lin Lu, Ying Han.

Repeated cocaine exposure causes compensatory neuroadaptations in neurons in the nucleus accumbens (NAc), a region that mediates reinforcing effects of drugs. Previous studies suggested a role for adenosine monophosphate-activated protein kinase (AMPK), a cellular energy sensor, in modulating neuronal morphology and membrane excitability. However, the potential involvement of AMPK in cocaine use disorder is still unclear. The present study employed a cocaine self-administration model in rats to investigate the effect of AMPK and its target cyclic adenosine monophosphate response element binding protein-regulated transcriptional co-activator 1 (CRTC1) on cocaine reinforcement and the motivation for cocaine. We found that intravenous cocaine self-administration significantly decreased AMPK activity in the NAc shell (NAcsh), which persisted for at least 7 days of withdrawal. Cocaine reinforcement, reflected by self-administration behavior, was significantly prevented or enhanced by augmenting or suppressing AMPK activity pharmacologically and genetically, respectively. No difference in sucrose self-administration behavior was found after the same manipulations. The inhibition of AMPK activity in the NAcsh also increased the motivation for cocaine in progressive-ratio schedules of reinforcement, whereas the activation of AMPK had no effect. The knockdown of CRTC1 in the NAcsh significantly impaired cocaine reinforcement, which was rescued by pharmacologically increasing AMPK activity. Altogether, these results indicate that AMPK in the NAcsh is critical for cocaine reinforcement, possibly via the regulation of CRTC1 signaling. These findings may help reveal potential therapeutic targets and have important implications for the treatment of cocaine use disorder and relapse.

DOI: https://doi.org/10.1038/s41398-022-02299-w
Cell Biochem Funct. 2023 Jan 01.

Vitamin D and lactoferrin attenuate stress-induced colitis in Wistar rats via enhancing AMPK expression with inhibiting mTOR-STAT3 signaling and modulating autophagy.

Marian F L Abdelmalak, Dina S Abdelrahim, Tari M A George Michael, Omnia M Abdel-Maksoud, Jolly M W Labib.

  Irritable bowel syndrome (IBS) is a global gastrointestinal disorder closely related to psychological stress exposure and local colonic inflammation. Herein, we investigated the effect of wrap-restraint stress (WRS) on rat behavior, on adenosine monophosphate-activated protein kinase-mammalian/mechanistic target of rapamycin-signal transducer and activator of transcription 3 (AMPK-mTOR-STAT3) signaling, and autophagy in colonic mucosa. The impact of chronic administration of vitamin D3 and lactoferrin was compared. Twenty-four male Wistar rats were randomly divided into four groups. Chronic WRS protocol was applied as a rodent model of IBS. Group I: naïve animals, Group II: WRS animals, Group III: WRS-exposed and treated with vitamin D3 (500 IU/kg/day), and Group IV: WRS-exposed and treated with lactoferrin (300 mg/kg/day). In this study, we found that chronic administration of each of vitamin D3 and lactoferrin resulted in a significant increase in social interaction test, interleukin-10, AMPK, optical density of LC3B, goblet cell count and marked decrease in serum cortisol level, STAT3, inflammatory cell count, and optical density of mTOR in comparison to the WRS rats. Our findings suggest that both vitamin D3 and Lactoferrin could augment colonic autophagy through enhanced AMPK expression and inhibition of mTOR-STAT3 signaling, which offers practical insights into their clinical use in the prevention and therapy of IBS. However, lactoferrin intake as a nutritional supplement could be more helpful for stress-induced colitis treatment than vitamin D3.

Keywords:  AMPK-mTOR-STAT3 signaling; autophagy; irritable bowel syndrome; lactoferrin; vitamin D3; wrap-restraint stress

DOI:  https://doi.org/10.1002/cbf.3774
Oncol Lett. 2023 Jan;25(1): 42

Fumarate hydratase inhibits non-small cell lung cancer metastasis via inactivation of AMPK and upregulation of DAB2.

Anupama Vadhan, Yi-Fang Yang, Yun-Ming Wang, Pang-Yu Chen, Shey-Cherng Tzou, Kuang-Hung Cheng, Stephen Chu-Sung Hu, Tian-Lu Cheng, Yen-Yun Wang, Shyng-Shiou F Yuan.

  Lung cancer is one of the leading causes of cancer mortality worldwide. As it is often first diagnosed only when cancer metastasis has already occurred, the development of effective biomarkers for the risk prediction of cancer metastasis, followed by stringent monitoring and the early treatment of high-risk patients, is essential for improving patient survival. Cancer cells exhibit alterations in metabolic pathways that enable them to maintain rapid growth and proliferation, which are quite different from the metabolic pathways of normal cells. Fumarate hydratase (FH, fumarase) is a well-known tricarboxylic acid cycle enzyme that catalyzes the reversible hydration/dehydration of fumarate to malate. The current study sought to investigate the relationship between FH expression levels and the outcome of patients with lung cancer. FH was knocked down in lung cancer cells using shRNA or overexpressed using a vector, and the effect on migration ability was assessed. Furthermore, the role of AMP-activated protein kinase (AMPK) phosphorylation and disabled homolog 2 in the underlying mechanism was investigated using an AMPK inhibitor approach. The results showed that in lung cancer tissues, low FH expression was associated with lymph node metastasis, tumor histology and recurrence. In addition, patients with low FH expression exhibited a poor overall survival in comparison with patients having high FH expression. When FH was overexpressed in lung cancer cells, cell migration was reduced with no effect on cell proliferation. Furthermore, the level of phosphorylated (p-)AMPK, an energy sensor molecule, was upregulated when FH was knocked down in lung cancer cells, and the inhibition of p-AMPK led to an increase in the expression of disabled homolog 2, a tumor suppressor protein. These findings suggest that FH may serve as an effective biomarker for predicting the prognosis of lung cancer and as a therapeutic mediator.

Keywords:  AMPK; disabled homolog 2; fumarate hydratase; lung cancer; migration

DOI:  https://doi.org/10.3892/ol.2022.13627
Heliyon. 2022 Dec;8(12): e12385

LOX-1 attenuates high glucose-induced autophagy via AMPK/HNF4α signaling in HLSECs.

Qidang Duan, Huiling Si, Limin Tian, Na Zhang, Jumei Qiu, Jing Yu, Jing Liu, Qi Zhang.

  Type 2 diabetes mellitus (T2DM) combined with nonalcoholic fatty liver disease (NAFLD) is a common cause of death. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is involved in the regulation of autophagy and associated with a variety of diseases, such as atherosclerosis, diabetes, and NAFLD. This study aimed to investigate the effect of LOX-1 on autophagy induced by high glucose levels in human liver sinusoidal endothelial cells (HLSECs) and whether it regulates autophagy through the adenosine monophosphate-activated protein kinase/hepatocyte nuclear factor 4α (AMPK/HNF4α) pathway. In this study, HLSECs cultured with high glucose medium showed increased expression of LOX-1, whereas autophagy was inhibited. High glucose levels decreased the AMPK phosphorylation, increased the HNF4α phosphorylation, and retained the HNF4α in the cytoplasm. By contrast, silencing of LOX-1 reversed the phenomenon induced by high glucose levels and restored the HNF4a localization. Taken together, our findings reveal a novel mechanism of high glucose-induced autophagy in HLSECs, namely, the LOX-1-mediated AMPK/HNF4α signaling pathway. Therefore, LOX-1 is an important target molecule for the regulation of autophagy in HLSECs.

Keywords:  AMPK; Autophagy; HLSECs; HNF4α; LOX-1

DOI:  https://doi.org/10.1016/j.heliyon.2022.e12385
Mol Metab. 2022 Dec 28. pii: S2212-8778(22)00230-7. [Epub ahead of print] 101661

AMPK integrates metabolite and kinase-based immunometabolic control in macrophages.

Iain R Phair, Raid B Nisr, Andrew J M Howden, Marc Foretz, Douglas Lamont, Benoit Viollet, Graham Rena.

Previous mechanistic studies on immunometabolism have focused on metabolite-based paradigms of regulation, such as itaconate. Here, we combine whole cell quantitative proteomics with gene knockout of AMPKα1, to demonstrate integration of metabolite and kinase-based immunometabolic control. Comparing macrophages with AMPKα1 catalytic subunit deletion with wild-type, inflammatory markers are largely unchanged in unstimulated cells, but with an LPS stimulus, AMPKα1 knockout leads to a striking M1 hyperpolarisation. Deletion of AMPKα1 also resulted in increased expression of rate-limiting enzymes involved in itaconate synthesis, metabolism of glucose, arginine, prostaglandins and cholesterol. Consistent with this, we observed functional changes in prostaglandin synthesis and arginine metabolism. Selective AMPKα1 activation also unlocks additional regulation of IL-6 and IL-12 in M1 macrophages. Together, our results validate AMPK as a pivotal immunometabolic regulator in macrophages.

DOI: https://doi.org/10.1016/j.molmet.2022.101661
Clin Transl Med. 2023 Jan;13(1): e1158

CircZSWIM6 mediates dysregulation of ECM and energy homeostasis in ageing chondrocytes through RPS14 post-translational modification.

Zhe Gong, Kefan Wang, Junxin Chen, Jinjin Zhu, Zhenhua Feng, Chenxin Song, Zheyuan Zhang, Haoming Wang, Shunwu Fan, Shuying Shen, Xiangqian Fang.

   BACKGROUND: Circular RNAs (CircRNAs) are important and have different roles in disease progression. Herein, we aim to elucidate the roles of a novel CircRNA (CircZSWIM6) which is upregulated in ageing chondrocytes.
METHODS: We verified the roles of CircZSWIM6 in senescent and osteoarthritis (OA) development in vitro through CircZSWIM6 knockdown and overexpression. RNA pulldown assay and RNA binding protein immunoprecipitation were performed to identify the interaction between CircZSWIM6 and Ribosomal protein S14 (RPS14). The roles of CircZSWIM6 in ageing-related OA were also confirmed in non-traumatic and traumatic model respectively.
RESULTS: CircZSWIM6 regulates extracellular matrix (ECM) and energy metabolism in ageing chondrocyte. Mechanistically, CircZSWIM6 competitively bound to the E3 ligase STUB1 binding site on RPS14 (K125) to inhibit proteasomal degradation of RPS14 to maintain RPS14 function. CircZSWIM6-RPS14 axis is highly associated with AMPK signaling transduction, which keeps energy metabolism in chondrocyte. Furthermore, CircZSWIM6 AAV infection leads to senescent and OA phenotypes in a non-traumatic model and accelerates OA progression in a traumatic model.
CONCLUSION: Our results revealed a significant role of CircZSWIM6 in age-related OA by regulating ECM metabolism and AMPK-associated energy metabolism. We highlight the CircZSWIM6-RPS14-PCK1-AMPK axis is a potential biomarker for OA.

Keywords:  AMPK; CircZSWIM6; RPS14; metabolism; osteoarthritis; senescence

DOI:  https://doi.org/10.1002/ctm2.1158
Front Pharmacol. 2022 ;13 1056687

Calycosin induces autophagy and apoptosis via Sestrin2/AMPK/mTOR in human papillary thyroid cancer cells.

Na Qu, Junsheng Qu, Na Huang, Kexin Zhang, Tongtong Ye, Junfeng Shi, Bing Chen, Chengxia Kan, Jingwen Zhang, Fang Han, Ningning Hou, Xiaodong Sun, Ruiyan Pan.

  Calycosin, one of small molecules derived from astragalus, has anti-tumor effects in various tumors. However, the effects of calycosin on papillary thyroid cancer (PTC) remain unclear. This study aimed to explore the anti-tumor ability of calycosin on human PTC and its potential mechanisms. The B-CPAP cells were treated with calycosin, then cell proliferation, apoptosis and invasiveness were measured by CCK8 assay, flow cytometry, wound healing and transwell invasion assay, respectively. The cells were also performed by whole transcriptome microarray bioinformatics analysis. Apoptosis and autophagy-related markers or proteins were measured by qRT-PCR or western blot. Sestrin2-mediated AMPK/mTOR pathways were determined by western blot. We found that calycosin inhibited migration and invasion of B-CPAP cells and induced apoptosis (Bax/Bcl-2) and autophagy (LC3II/I, Beclin1) of B-CPAP cells. Differential expressed genes were screened between the calycosin-treated cells and control (524 genes upregulated and 328 genes downregulated). The pathway enrichment suggested that the role of calycosin in B-CPAP cells is closely related to apoptosis-related genes and p70S6 Kinase. Transmission electron microscopy found an increase in autophagosomes in calycosin-treated cells. Sestrin2 in human PTC tissues and B-CPAP cells was lower than in normal thyroid tissues and cells. And the pharmacological effects of calycosin in PTC cells were related to Sestrin2 activation, increased p-AMPK and inhibited p-mTOR and p-p70S6Kinase; these alterations were reversed when silencing Sestrin2. In conclusion, calycosin has an inhibitory effect on PTC via promoting apoptosis and autophagy through the Sestrin2/AMPK/mTOR pathway.

Keywords:  Sestrin2; autophagy; calycosin; small molecules; therapy; thyroid cancer

DOI:  https://doi.org/10.3389/fphar.2022.1056687
Elife. 2023 Jan 04. pii: e81198. [Epub ahead of print]12

Metformin protects trabecular meshwork against oxidative injury via activating integrin/ROCK signals.

Lijuan Xu, Xinyao Zhang, Yin Zhao, Xiaorui Gang, Tao Zhou, Jialing Han, Yang Cao, Binyan Qi, Shuning Song, Xiaojie Wang, Yuanbo Liang.

  This study aimed to investigate the protective effect of metformin on trabecular meshwork (TM) and explore its molecular mechanisms in vivo and in vitro. Ocular hypertension (OHT) mouse models were induced with dexamethasone and further treated with metformin to determine the intraocular pressure (IOP)-lowering effect. Cultured human TM cells (HTMCs) were pre-stimulated with tert-butyl hydroperoxide (tBHP) to induce oxidative damage and then supplemented with metformin for another 24 hr. The expression of fibrotic markers and integrin/Rho-associated kinase (ROCK) signals, including α-smooth muscle actin (α-SMA), transforming growth factor-β (TGF-β), fibronectin, integrin beta 1, ROCK 1/2, AMP-activated protein kinase, myosin light chain 1, and F-actin were determined by western blotting and immunofluorescence. Reactive oxygen species (ROS) content was analysed using flow cytometry. Transmission electron microscopy was performed to observe microfilaments in HTMCs. It showed that metformin administration reduced the elevated IOP and alleviated the fibrotic activity of aqueous humour outflow in OHT models. Additionally, metformin rearranged the disordered cytoskeleton in the TM both in vivo and in vitro and significantly inhibited ROS production and activated integrin/ROCK signalling induced by tBHP in HTMCs. These results indicated that metformin reduced the elevated IOP in steroid-induced OHT mouse models and exerted its protective effects against oxidative injury by regulating cytoskeleton remodelling through the integrin/ROCK pathway. This study provides new insights into metformin use and preclinical evidence for the potential treatment of primary open-angle glaucoma.

Keywords:  cell biology; cytoskeleton remodelling; metformin; mouse; open-angle glaucoma; trabecular meshwork

DOI:  https://doi.org/10.7554/eLife.81198