bims-amsmem 2022-12-11 papers

bims-amsmem

Biomed News

on AMPK signaling mechanism in energy metabolism

Issue of 2022‒12‒11
fourteen papers selected by
Dipsikha Biswas, Københavns Universitet

The bidirectional relationship between AMPK pathway activation and myokine secretion in skeletal muscle: How it affects energy metabolism.
Reactive oxygen species-mediated oxidative stress accelerates glycolysis via activation of the CaMKKβ/AMPK pathway in the yak longissimus dorsi postmortem.
AMP-activated protein kinase is a key regulator of obesity-associated factors.
Genistein activated SIRT1-AMPK signaling pathway mediated by ERβ-FOXO1-Nampt to reduce fat accumulation in chicken hepatocytes.
The glucotoxicity protecting effect of honokiol in human hepatocytes via directly activating AMPK.
The combination of exercise and metformin inhibits TGF-β1/Smad pathway to attenuate myocardial fibrosis in db/db mice by reducing NF-κB-mediated inflammatory response.
miR-1 Mediated AMPK Pathway on Cardiomyocyte Apoptosis in Hypertensive Rats.
AMPK regulates homeostasis of invasion and viability in trophoblasts by redirecting glucose metabolism: Implications for pre-eclampsia.
Atg1 phosphorylation is activated by AMPK and indispensable for autophagy induction in insects.
Metformin in therapeutic applications in human diseases: its mechanism of action and clinical study.
SIRT3 Enhances the Protective Role of Propofol in Postoperative Cognitive Dysfunction via Activating Autophagy Mediated by AMPK/mTOR Pathway.
A signalling pathway for transcriptional regulation of sleep amount in mice.
Energy metabolism in skeletal muscle cells from donors with different body mass index.
Metformin enhances the osteogenic activity of rat bone marrow mesenchymal stem cells by inhibiting oxidative stress induced by diabetes mellitus: an in vitro and in vivo study.

Front Physiol. 2022 ;13 1040809

The bidirectional relationship between AMPK pathway activation and myokine secretion in skeletal muscle: How it affects energy metabolism.

Mahdi Ahsan, Léa Garneau, Céline Aguer.

  Myokines are peptides and proteins secreted by skeletal muscle cells, into the interstitium, or in the blood. Their regulation may be dependent or independent of muscle contraction to induce a variety of metabolic effects. Numerous myokines have been implicated in influencing energy metabolism via AMP-activated protein kinase (AMPK) signalling. As AMPK is centrally involved in glucose and lipid metabolism, it is important to understand how myokines influence its signalling, and vice versa. Such insight will better elucidate the mechanism of metabolic regulation during exercise and at rest. This review encompasses the latest research conducted on the relationship between AMPK signalling and myokines within skeletal muscles via autocrine or paracrine signalling.

Keywords:  AMPK; cell signalling; glucose metabolism; lipid metabolism; myokines; skeletal muscle

DOI:  https://doi.org/10.3389/fphys.2022.1040809
J Sci Food Agric. 2023 Jan 30. 103(2): 514-523

Reactive oxygen species-mediated oxidative stress accelerates glycolysis via activation of the CaMKKβ/AMPK pathway in the yak longissimus dorsi postmortem.

Xijin Zhu, Xiangying Kong, Lei Zang, Nan Sun, Qunli Yu, Ling Han.

  BACKGROUND: Adenosine monophosphate-activated protein kinase (AMPK) is instrumental in the initiation of early postmortem glycolysis and the advent of pale, soft, and exudative (PSE) meat when cellular energy is altered. However, conflicting studies show that AMPK activation without corresponding energy level changes in PSE meat challenges this long-held notion. Here, we examined the effects of reactive oxygen species (ROS)-mediated oxidative stress on AMPK activation in the context of glycolysis, protein solubility, and water-holding capacity (WHC) in the postmortem yak longissimus dorsi (LD) muscle. Further, we explored the mechanisms underlying these effects.RESULTS: Hydrogen peroxide (H2 O2 ) significantly augmented the degree of oxidative stress, increasing the production of ROS and malondialdehyde excessive production and reducing the activity of the anti-oxidants superoxide dismutase and glutathione peroxidase. In turn, oxidative stress dramatically promoted AMPK activation and glycolysis by increasing glycogen depletion and promoting hexokinase and phosphofructokinase activity. Subsequently, lactic acid accumulation increased, leading to a rapid decline in pH, which aggravated protein solubility degree and centrifugal loss in the early postmortem yak LD muscle. Importantly, these changes caused by oxidative stress were eliminated by the AMPK inhibitor. Mechanistically, oxidative stress elevated calcium ion (Ca2+ ) levels, which mobilized calcium/calmodulin-dependent protein kinase β (CaMKKβ) and AMPK. Rescue experiments confirmed that the increases were attenuated using Ca2+ and CaMKKβ chelators, respectively.
CONCLUSION: These results indicated that oxidative stress caused by ROS hastened early-stage postmortem glycolysis and reduced the WHC of yak meat. These effects were likely mediated by the alternative and energy-independent CaMKKβ/AMPK signaling pathway. © 2022 Society of Chemical Industry.

Keywords:  AMP-activated protein kinase (AMPK); calcium/calmodulin-dependent protein kinase (CaMKKβ); oxidative stress; postmortem glycolysis; water-holding capacity (WHC)

DOI:  https://doi.org/10.1002/jsfa.12161
Cell Biochem Funct. 2022 Dec 05.

AMP-activated protein kinase is a key regulator of obesity-associated factors.

Roohollah Mohseni, Maryam Teimouri, Mohsen Safaei, Zahra Arab Sadeghabadi.

  An imbalance between caloric intake and energy expenditure leads to obesity. Obesity is an important risk factor for the development of several metabolic diseases including insulin resistance, metabolic syndrome, type 2 diabetes mellitus, and cardiovascular disease. So, controlling obesity could be effective in the improvement of obesity-related diseases. Various factors are involved in obesity, such as AMP-activated protein kinases (AMPK), silent information regulators, inflammatory mediators, oxidative stress parameters, gastrointestinal hormones, adipokines, angiopoietin-like proteins, and microRNAs. These factors play an important role in obesity by controlling fat metabolism, energy homeostasis, food intake, and insulin sensitivity. AMPK is a heterotrimeric serine/threonine protein kinase known as a fuel-sensing enzyme. The central role of AMPK in obesity makes it an attractive molecule to target obesity and related metabolic diseases. In this review, the critical role of AMPK in obesity and the interplay between AMPK and obesity-associated factors were elaborated.

Keywords:  AMP-activated protein kinases; inflammation; obesity; oxidative stress; silent information regulators

DOI:  https://doi.org/10.1002/cbf.3767
Life Sci. 2022 Dec 01. pii: S0024-3205(22)00959-6. [Epub ahead of print]312 121259

Genistein activated SIRT1-AMPK signaling pathway mediated by ERβ-FOXO1-Nampt to reduce fat accumulation in chicken hepatocytes.

Zhihao Jiang, Huihui Wang, Ying Yang, Yao Yao, Haitian Ma.

  Excessive fat accumulation in broiler chickens would seriously threaten the poultry industry. It leads to lower feed conversion rate and worse meat quality. Even worse, it harms the consumers' health due to the intake of high-fat chicken products. Dietary supplements with bioactive ingredients have been considered an effective way to solve this problem. Genistein is the primary phytoestrogen in soybean. Its fat-reduction effect has been reported, but the molecular mechanism is unclear. The present study found that genistein reduced lipid droplets accumulation by regulating lipid metabolism-related factors expression in chicken hepatocytes. The research showed that genistein significantly increased phosphor (p)-AMP-activated protein kinase (p-AMPK) and Sirtuin 1 (SIRT1) protein expressions. The effect of genistein on reducing lipid droplets accumulation and upregulating p-AMPK protein level was blocked entirely when pretreated with SIRT1 inhibitor. These results implied that SIRT1 is required to activate AMPK. Furthermore, genistein treatment significantly upregulated the SIRT1 protein level when pretreated with AMPK inhibitor. We demonstrated that the activation of estrogen receptor β-Forkhead box O1-Nicotinamide phosphoribosyl transferase (ERβ-FOXO1-Nampt) signaling pathway upregulated the NAD+ concentration in hepatocytes, and activated SIRT1 ultimately. In summary, we demonstrated that genistein suppressed lipid droplets accumulation in chicken hepatocytes by activating SIRT1-AMPK. The SIRT1-AMPK signaling pathway was mediated by ERβ-FOXO1-Nampt. These findings increase our understanding of the mechanisms of genistein on fat reduction, and provide compelling evidence for it as a nutritional supplement to prevent excessive fat deposition and lipid metabolism-related diseases in animals and even humans.

Keywords:  ERβ-FOXO1-Nampt; Fat-deposition; Genistein; Hepatocytes; SIRT1-AMPK

DOI:  https://doi.org/10.1016/j.lfs.2022.121259
Front Nutr. 2022 ;9 1043009

The glucotoxicity protecting effect of honokiol in human hepatocytes via directly activating AMPK.

Hui Liu, Wu Luo, Jiazheng Liu, Xincong Kang, Jianming Yan, Tingting Zhang, Lan Yang, Lu Shen, Dongbo Liu.

  Introduction: Sustained hyperglycemia causes glucotoxicity, which has been regarded as a contributor to hepatocyte damage in type 2 diabetes (T2D) and its metabolic comorbidities. Honokiol is a natural biphenolic component derived from the dietary supplement Magnolia officinalis extract. This study aimed to investigate the effects of honokiol on glucose metabolism disorders and oxidative stress in hepatocytes and the underlying mechanisms.Methods: HepG2 cells were treated with glucosamines (18 mM) to induce glucotoxicity as a diabetic complication model in vitro.
Results and discussion: Honokiol significantly increased glucose consumption, elevated 2-NBDG uptake, and promoted GLUT2 translocation to the plasma membrane in glucosamine-treated HepG2 cells, indicating that honokiol ameliorates glucose metabolism disorders. Furthermore, glucosamine-induced ROS accumulation and loss of mitochondrial membrane potential were markedly reduced by honokiol, suggesting that honokiol alleviated glucotoxicity-induced oxidative stress. These effects were largely abolished by compound C, an AMPK inhibitor, suggesting an AMPK activation-dependent manner of honokiol function in promoting glucose metabolism and mitigating oxidative stress. Molecular docking results revealed that honokiol could interact with the amino acid residues (His151, Arg152, Lys243, Arg70, Lys170, and His298) in the active site of AMPK. These findings provide new insights into the antidiabetic effect of honokiol, which may be a promising agent for the prevention and treatment of T2D and associated metabolic comorbidities.

Keywords:  AMPK; glucose metabolism disorder; glucotoxicity; honokiol; oxidative stress; type 2 diabetes

DOI:  https://doi.org/10.3389/fnut.2022.1043009
Biomed Pharmacother. 2022 Dec 05. pii: S0753-3322(22)01469-X. [Epub ahead of print]157 114080

The combination of exercise and metformin inhibits TGF-β1/Smad pathway to attenuate myocardial fibrosis in db/db mice by reducing NF-κB-mediated inflammatory response.

Jingjing Liu, Jiao Lu, Liumei Zhang, Yuting Liu, Yuan Zhang, Yaran Gao, Xinmeng Yuan, Mengqi Xiang, Qiang Tang.

  Persistent hyperglycemia increases inflammation response, promoting the development of myocardial fibrosis. Based on our previous research that exercise and metformin alone or their combination intervention could attenuate myocardial fibrosis in db/db mice, this study aimed to further explore the underlying mechanisms by which these interventions attenuate myocardial fibrosis in early diabetic cardiomyopathy. Forty BKS db/db mice were randomly divided into four groups. Diabetic db/db mice without intervention were in the C group. Aerobic exercise (7-12 m/min, 30-40 min/day, 5 days/week) was performed in the E group. Metformin (300 mg·kg-1·day-1) was administered in the M group. Exercise combined with metformin was performed in the EM group. Ten wild-type mice were in the WT group. All interventions were administered for 8 weeks. Results showed that the expression levels of α-SMA, Collagen I, and Collagen III were increased in 16-week-old db/db mice, which were reversed by exercise and metformin alone or their combination intervention. All interventions attenuated the level of TGF-β1/Smad2/3 pathway-related proteins and reduced the expression of inflammatory signaling pathway-regulated proteins TNF-α, p-IκBα/IκBα, and p-NF-κB p65/NF-κB p65 in db/db mice. Furthermore, metformin intervention inhibited HNF4α expression via AMPK activation, whereas exercise intervention increased the expression of IL-6 instead of activating AMPK. In conclusion, exercise and metformin alone or their combination intervention inhibited the TGF-β1/Smad pathway to attenuate myocardial fibrosis by reducing NF-κB-mediated inflammatory response. The anti-fibrotic effects were regulated by metformin-activated AMPK or exercise-induced elevation of IL-6, whereas their combination intervention showed no synergistic effects.

Keywords:  Diabetic cardiomyopathy; Exercise; Inflammation; Metformin; Myocardial fibrosis

DOI:  https://doi.org/10.1016/j.biopha.2022.114080
Cell Mol Biol (Noisy-le-grand). 2022 Jul 31. 68(7): 135-140

miR-1 Mediated AMPK Pathway on Cardiomyocyte Apoptosis in Hypertensive Rats.

Xiaoli Huang, Jinlin Wang.

In recent years, it has been found that miRNA has a very close relationship with cardiovascular system diseases. Heart disease is accompanied by a change of the miRNA expression spectrum. Changing the expression of miRNA in or out of cells can cause heart diseases such as myocardial infarction, hypertrophy or arrhythmia. Mitogen-activated protein kinases (MAPKs) are important transmitters of cell surface signals to the nucleus. The family influences the biological responses of cells (e.g., proliferation, differentiation, transformation and apoptosis) by affecting the transcription and regulation of genes in animal cells. Based on the above background, the purpose of this study was to study the effect of the mir-1-mediated AMPK pathway on cardiomyocyte apoptosis in hypertensive rats. The expression level of miRNA-1 in cultured rat H9c2 cardiomyocytes was detected by real-time PCR to determine the success of the transfection. MTT method was used to detect the cell viability. Flow cytometry was used to detect the cell apoptosis, and real-time PCR and Western blot were used to detect the mRNA and protein expression of bcl-2. The results were compared with those of H9c2 cells (blank control group) and miRNA negative control fragments (negative control group). As an important kinase regulating energy homeostasis, AMPK is one of the central regulators of metabolism in eukaryotic cells and organisms, responsible for regulating cellular capacity input and output and maintaining the smooth functioning of cellular physiological activities. At the same time, AMPK is a key protein involved in a variety of signaling pathways. The results showed that the apoptosis rate of myocardial cells in the miRNA-1 group decreased (0.710 ± 0.009661)% vs (1.066667 ± 0.02603)% compared with that in the spontaneous hypertension control group (P < 0.001). The transfected miRNA-1mimics can up-regulate the expression of miRNA-1 in cells, inhibit the proliferation of cardiomyocytes and promote apoptosis.

DOI: https://doi.org/10.14715/cmb/2022.68.7.22
Cell Prolif. 2022 Dec 08. e13358

AMPK regulates homeostasis of invasion and viability in trophoblasts by redirecting glucose metabolism: Implications for pre-eclampsia.

Ping Xu, Yangxi Zheng, Jiujiang Liao, Mingyu Hu, Yike Yang, Baozhen Zhang, Mark D Kilby, Huijia Fu, Yamin Liu, Fumei Zhang, Liling Xiong, Xiyao Liu, Huili Jin, Yue Wu, Jiayu Huang, Tingli Han, Li Wen, Rufei Gao, Yong Fu, Xiujun Fan, Hongbo Qi, Philip N Baker, Chao Tong.

Pre-eclampsia (PE) is deemed an ischemia-induced metabolic disorder of the placenta due to defective invasion of trophoblasts during placentation; thus, the driving role of metabolism in PE pathogenesis is largely ignored. Since trophoblasts undergo substantial glycolysis, this study aimed to investigate its function and regulatory mechanism by AMPK in PE development. Metabolomics analysis of PE placentas was performed by gas chromatography-mass spectrometry (GC-MS). Trophoblast-specific AMPKα1-deficient mouse placentas were generated to assess morphology. A mouse PE model was established by Reduced Uterine Perfusion Pressure, and placental AMPK was modulated by nanoparticle-delivered A769662. Trophoblast glucose uptake was measured by 2-NBDG and 2-deoxy-d-[3 H] glucose uptake assays. Cellular metabolism was investigated by the Seahorse assay and GC-MS.PE complicated trophoblasts are associated with AMPK hyperactivation due not to energy deficiency. Thereafter, AMPK activation during placentation exacerbated PE manifestations but alleviated cell death in the placenta. AMPK activation in trophoblasts contributed to GLUT3 translocation and subsequent glucose metabolism, which were redirected into gluconeogenesis, resulting in deposition of glycogen and accumulation of phosphoenolpyruvate; the latter enhanced viability but compromised trophoblast invasion. However, ablation of AMPK in the mouse placenta resulted in decreased glycogen deposition and structural malformation. These data reveal a novel homeostasis between invasiveness and viability in trophoblasts, which is mechanistically relevant for switching between the 'go' and 'grow' cellular programs.

DOI: https://doi.org/10.1111/cpr.13358
Insect Biochem Mol Biol. 2022 Dec 06. pii: S0965-1748(22)00170-9. [Epub ahead of print] 103888

Atg1 phosphorylation is activated by AMPK and indispensable for autophagy induction in insects.

Haigang Zhao, Shihui Long, Suning Liu, Dongwei Yuan, Danyan Huang, Jing Xu, Qiuqin Ma, Guirong Wang, Jian Wang, Sheng Li, Ling Tian, Kang Li.

  Phosphorylation is a key post-translational modification in regulating autophagy in yeast and mammalians, yet it is not fully illustrated in invertebrates such as insects. ULK1/Atg1 is a functionally conserved serine/threonine protein kinase involved in autophagosome initiation. As a result of alternative splicing, Atg1 in the silkworm, Bombyx mori, is present as three mRNA isoforms, with BmAtg1c showing the highest expression levels. Here, we found that BmAtg1c mRNA expression, BmAtg1c protein expression and phosphorylation, and autophagy simultaneously peaked in the fat body during larval-pupal metamorphosis. Importantly, two BmAtg1c phosphorylation sites were identified at Ser269 and Ser270, which were activated by BmAMPK, the major energy-sensing kinase, upon stimulation with 20-hydroxyecdysone and starvation; additionally, these Atg1 phosphorylation sites are evolutionarily conserved in insects. The two BmAMPK-activated phosphorylation sites in BmAtg1c were found to be required for BmAMPK-induced autophagy. Moreover, the two corresponding DmAtg1 phosphorylation sites in the fruit fly, Drosophila melanogaster, are functionally conserved for autophagy induction. In conclusion, AMPK-activated Atg1 phosphorylation is indispensable for autophagy induction and evolutionarily conserved in insects, shedding light on how various groups of organisms differentially regulate ULK1/Atg1 phosphorylation for autophagy induction.

Keywords:  20-Hydroxyecdysone; AMPK; Autophagy; BmAtg1c; DmAtg1; Phosphorylation modification; Starvation

DOI:  https://doi.org/10.1016/j.ibmb.2022.103888
Mol Biomed. 2022 Dec 09. 3(1): 41

Metformin in therapeutic applications in human diseases: its mechanism of action and clinical study.

Yang Du, Ya-Juan Zhu, Yi-Xin Zhou, Jing Ding, Ji-Yan Liu.

  Metformin, a biguanide drug, is the most commonly used first-line medication for type 2 diabetes mellites due to its outstanding glucose-lowering ability. After oral administration of 1 g, metformin peaked plasma concentration of approximately 20-30 μM in 3 h, and then it mainly accumulated in the gastrointestinal tract, liver and kidney. Substantial studies have indicated that metformin exerts its beneficial or deleterious effect by multiple mechanisms, apart from AMPK-dependent mechanism, also including several AMPK-independent mechanisms, such as restoring of redox balance, affecting mitochondrial function, modulating gut microbiome and regulating several other signals, such as FBP1, PP2A, FGF21, SIRT1 and mTOR. On the basis of these multiple mechanisms, researchers tried to repurpose this old drug and further explored the possible indications and adverse effects of metformin. Through investigating with clinical studies, researchers concluded that in addition to decreasing cardiovascular events and anti-obesity, metformin is also beneficial for neurodegenerative disease, polycystic ovary syndrome, aging, cancer and COVID-19, however, it also induces some adverse effects, such as gastrointestinal complaints, lactic acidosis, vitamin B12 deficiency, neurodegenerative disease and offspring impairment. Of note, the dose of metformin used in most studies is much higher than its clinically relevant dose, which may cast doubt on the actual effects of metformin on these disease in the clinic. This review summarizes these research developments on the mechanism of action and clinical evidence of metformin and discusses its therapeutic potential and clinical safety.

Keywords:  AMPK; Adverse effects; Gut microbiome; Metformin; Mitochondria; Redox balance

DOI:  https://doi.org/10.1186/s43556-022-00108-w
Front Biosci (Landmark Ed). 2022 Nov 08. 27(11): 303

SIRT3 Enhances the Protective Role of Propofol in Postoperative Cognitive Dysfunction via Activating Autophagy Mediated by AMPK/mTOR Pathway.

Shang Li, Yi Zhou, Huaying Hu, Xiaodong Wang, Junjun Xu, Chaobo Bai, Junliang Yuan, Dongliang Zhang.

  BACKGROUND: Postoperative cognitive dysfunction (POCD) is a common complication after surgery and anesthesia. In this study, we aimed to determine the neuroprotective mechanism of Sirtuin 3 (SIRT3) and propofol in POCD.METHODS: The cognitive dysfunction models in C57BL/6J mice were induced and treated, then cognitive function of mice were tested using morris water maze and novel object recognition tests. Primary neurons were stimulated by lipopolysaccharide (LPS) to mimic neuroinflammation during POCD. Meanwhile, cells were treated with propofol. 3-methyladenine (3-MA) was administrated to inhibit autophagy in neurons. SIRT3 overexpression vector was constructed to upregulate SIRT3. Biomarker changes in inflammation, oxidative stress and autophagy were determined in vivo and in vitro.
RESULTS: Propofol enhanced the spatial cognitive ability and novel objective recognition of POCD mice. Inflammation and oxidative stress were observed in the hippocampus, which were inhibited by propofol treatment. During POCD, SIRT3 expression and autophagy in the hippocampus was decreased; propofol activated autophagy and upregulated SIRT3. In LPS-stimulated neurons, SIRT3 upregulation enhanced the anti-inflammation and anti-oxidative stress roles of propofol; SIRT3 elevated propofol-activated autophagy in neurons undergoing LPS administration. Moreover, 3-MA reversed propofol-induced biomarker changes in inflammation, oxidative stress and autophagy in LPS-stimulated neurons. In POCD mice, SIRT3 upregulation enhanced the cognitive function during propofol treatment; SIRT3 overexpression elevated the inhibitory role of propofol in inflammation, oxidative stress and autophagy. AMPK/mTOR pathway was activated in response to propofol treatment and SIRT3 enhanced the signaling activation.
CONCLUSIONS: SIRT3 enhances the protective effect of propofol on POCD by triggering autophagy that eliminates oxidative stress and inhibits the production of pro-inflammatory cytokines.

Keywords:  SIRT3; autophagy; postoperative cognitive dysfunction; propofol

DOI:  https://doi.org/10.31083/j.fbl2711303
Nature. 2022 Dec 07.

A signalling pathway for transcriptional regulation of sleep amount in mice.

Rui Zhou, Guodong Wang, Qi Li, Fanxi Meng, Can Liu, Rui Gan, Dapeng Ju, Meimei Liao, Junjie Xu, Di Sang, Xue Gao, Shuang Zhou, Kejia Wu, Quanzhi Sun, Ying Guo, Chongyang Wu, Zhiyu Chen, Lin Chen, Bihan Shi, Haiyan Wang, Xia Wang, Huaiye Li, Tao Cai, Bin Li, Fengchao Wang, Hiromasa Funato, Masashi Yanagisawa, Eric Erquan Zhang, Qinghua Liu.

In mice and humans, sleep quantity is governed by genetic factors and exhibits age-dependent variation1-3. However, the core molecular pathways and effector mechanisms that regulate sleep duration in mammals remain unclear. Here, we characterize a major signalling pathway for the transcriptional regulation of sleep in mice using adeno-associated virus-mediated somatic genetics analysis4. Chimeric knockout of LKB1 kinase-an activator of AMPK-related protein kinase SIK35-7-in adult mouse brain markedly reduces the amount and delta power-a measure of sleep depth-of non-rapid eye movement sleep (NREMS). Downstream of the LKB1-SIK3 pathway, gain or loss-of-function of the histone deacetylases HDAC4 and HDAC5 in adult brain neurons causes bidirectional changes of NREMS amount and delta power. Moreover, phosphorylation of HDAC4 and HDAC5 is associated with increased sleep need, and HDAC4 specifically regulates NREMS amount in posterior hypothalamus. Genetic and transcriptomic studies reveal that HDAC4 cooperates with CREB in both transcriptional and sleep regulation. These findings introduce the concept of signalling pathways targeting transcription modulators to regulate daily sleep amount and demonstrate the power of somatic genetics in mouse sleep research.

DOI: https://doi.org/10.1038/s41586-022-05510-6
Front Physiol. 2022 ;13 982842

Energy metabolism in skeletal muscle cells from donors with different body mass index.

Parmeshwar B Katare, Andrea Dalmao-Fernandez, Abel M Mengeste, Håvard Hamarsland, Stian Ellefsen, Hege G Bakke, Eili Tranheim Kase, G Hege Thoresen, Arild C Rustan.

  Obesity and physical inactivity have a profound impact on skeletal muscle metabolism. In the present work, we have investigated differences in protein expression and energy metabolism in primary human skeletal muscle cells established from lean donors (BMI<25 kg/m2) and individuals with obesity (BMI>30 kg/m2). Furthermore, we have studied the effect of fatty acid pretreatment on energy metabolism in myotubes from these donor groups. Alterations in protein expression were investigated using proteomic analysis, and energy metabolism was studied using radiolabeled substrates. Gene Ontology enrichment analysis showed that glycolytic, apoptotic, and hypoxia pathways were upregulated, whereas the pentose phosphate pathway was downregulated in myotubes from donors with obesity compared to myotubes from lean donors. Moreover, fatty acid, glucose, and amino acid uptake were increased in myotubes from individuals with obesity. However, fatty acid oxidation was reduced, glucose oxidation was increased in myotubes from subjects with obesity compared to cells from lean. Pretreatment of myotubes with palmitic acid (PA) or eicosapentaenoic acid (EPA) for 24 h increased glucose oxidation and oleic acid uptake. EPA pretreatment increased the glucose and fatty acid uptake and reduced leucine fractional oxidation in myotubes from donors with obesity. In conclusion, these results suggest that myotubes from individuals with obesity showed increased fatty acid, glucose, and amino acid uptake compared to cells from lean donors. Furthermore, myotubes from individuals with obesity had reduced fatty acid oxidative capacity, increased glucose oxidation, and a higher glycolytic reserve capacity compared to cells from lean donors. Fatty acid pretreatment enhances glucose metabolism, and EPA reduces oleic acid and leucine fractional oxidation in myotubes from donor with obesity, suggesting increased metabolic flexibility after EPA treatment.

Keywords:  EPA; eicosapentaenoic acid; metabolism; mitochondria; obesity; skeletal muscle cells

DOI:  https://doi.org/10.3389/fphys.2022.982842
J Periodontal Implant Sci. 2022 Aug 29.

Metformin enhances the osteogenic activity of rat bone marrow mesenchymal stem cells by inhibiting oxidative stress induced by diabetes mellitus: an in vitro and in vivo study.

Kai Dong, Wen-Juan Zhou, Zhong-Hao Liu.

  PURPOSE: The purpose of this study was to determine whether metformin (MF) could alleviate the expresssion of reactive oxygen species (ROS) and improve the osteogenic ability of bone marrow mesenchymal stem cells derived from diabetic rats (drBMSCs) in vitro, and to evaluate the effect of MF on the ectopic osteogenesis of drBMSCs in a nude mouse model in vivo.METHODS: BMSCs were extracted from normal and diabetic rats. In vitro, a cell viability assay (Cell Counting Kit-8), tests of alkaline phosphatase (ALP) activity, and western blot analysis were first used to determine the cell proliferation and osteogenic differentiation of drBMSCs that were subjected to treatment with different concentrations of MF (0, 50, 100, 200, 500 μM). The cells were then divided into 5 groups: (1) normal rat BMSCs (the BMSCs derived from normal rats group), (2) the drBMSCs group, (3) the drBMSCs + Mito-TEMPO (10 μM, ROS scavenger) group, (4) the drBMSCs + MF (200 μM) group, and (5) the drBMSCs + MF (200 μM) + H2O2 (50 μM, ROS activator) group. Intracellular ROS detection, a senescence-associated β-galactosidase assay, ALP staining, alizarin red staining, western blotting, and immunofluorescence assays were performed to determine the effects of MF on oxidative stress and osteogenic differentiation in drBMSCs. In vivo, the effect of MF on the ectopic osteogenesis of drBMSCs was evaluated in a nude mouse model.
RESULTS: MF effectively reduced ROS levels in drBMSCs. The cell proliferation, ALP activity, mineral deposition, and osteogenic-related protein expression of drBMSCs were demonstrably higher in the MF-treated group than in the non-MF-treated group. H2O2 inhibited the effects of MF. In addition, ectopic osteogenesis was significantly increased in drBMSCs treated with MF.
CONCLUSIONS: MF promoted the proliferation and osteogenic differentiation of drBMSCs by inhibiting the oxidative stress induced by diabetes and enhenced the ectopic bone formation of drBMSCs in nude mice.

Keywords:  Bone regeneration; Diabetes mellitus; Metformin; Oxidative stress; Stem cells

DOI:  https://doi.org/10.5051/jpis.2106240312