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Salimi K, Alvandi M, Saberi Pirouz M, Rakhshan K, Howatson G. Regulating eEF2 and eEF2K in skeletal muscle by exercise. Arch Physiol Biochem 2024; 130:503-514. [PMID: 36633938 DOI: 10.1080/13813455.2023.2164898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 12/15/2022] [Accepted: 12/29/2022] [Indexed: 01/13/2023]
Abstract
Skeletal muscle is a flexible and adaptable tissue that strongly responds to exercise training. The skeletal muscle responds to exercise by increasing muscle protein synthesis (MPS) when energy is available. One of protein synthesis's major rate-limiting and critical regulatory steps is the translation elongation pathway. The process of translation elongation in skeletal muscle is highly regulated. It requires elongation factors that are intensely affected by various physiological stimuli such as exercise and the total available energy of cells. Studies have shown that exercise involves the elongation pathway by numerous signalling pathways. Since the elongation pathway, has been far less studied than the other translation steps, its comprehensive prospect and quantitative understanding remain in the dark. This study highlights the current understanding of the effect of exercise training on the translation elongation pathway focussing on the molecular factors affecting the pathway, including Ca2+, AMPK, PKA, mTORC1/P70S6K, MAPKs, and myostatin. We further discussed the mode and volume of exercise training intervention on the translation elongation pathway.What is the topic of this review? This review summarises the impacts of exercise training on the translation elongation pathway in skeletal muscle focussing on eEF2 and eEF2K.What advances does it highlight? This review highlights mechanisms and factors that profoundly influence the translation elongation pathway and argues that exercise might modulate the response. This review also combines the experimental observations focussing on the regulation of translation elongation during and after exercise. The findings widen our horizon to the notion of mechanisms involved in muscle protein synthesis (MPS) through translation elongation response to exercise training.
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Affiliation(s)
- Kia Salimi
- Department of Exercise Physiology, Faculty of Sport and Exercise Sciences, University of Tehran, Tehran, Iran
| | - Masoomeh Alvandi
- Department of Biological Science in Sport and Health, University of Shahid Beheshti, Tehran, Iran
| | - Mahdi Saberi Pirouz
- Student Research Committee, Iran University of Medical Sciences, Tehran, Iran
| | - Kamran Rakhshan
- Department of Medical Physiology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
- Electrophysiology Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Glyn Howatson
- Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK
- Water Research Group, North West University, Potchefstroom, South Africa
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2
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Kayashima Y, Townley-Tilson WHD, Vora NL, Boggess K, Homeister JW, Maeda-Smithies N, Li F. Insulin Elevates ID2 Expression in Trophoblasts and Aggravates Preeclampsia in Obese ASB4-Null Mice. Int J Mol Sci 2023; 24:ijms24032149. [PMID: 36768469 PMCID: PMC9917068 DOI: 10.3390/ijms24032149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/07/2023] [Accepted: 01/13/2023] [Indexed: 01/25/2023] Open
Abstract
Obesity is a risk factor for preeclampsia. We investigated how obesity influences preeclampsia in mice lacking ankyrin-repeat-and-SOCS-box-containing-protein 4 (ASB4), which promotes trophoblast differentiation via degrading the inhibitor of DNA-binding protein 2 (ID2). Asb4-/- mice on normal chow (NC) develop mild preeclampsia-like phenotypes during pregnancy, including hypertension, proteinuria, and reduced litter size. Wild-type (WT) and Asb4-/- females were placed on a high-fat diet (HFD) starting at weaning. At the age of 8-9 weeks, they were mated with WT or Asb4-/- males, and preeclamptic phenotypes were assessed. HFD-WT dams had no obvious adverse outcomes of pregnancy. In contrast, HFD-Asb4-/- dams had significantly more severe preeclampsia-like phenotypes compared to NC-Asb4-/- dams. The HFD increased white fat weights and plasma leptin and insulin levels in Asb4-/- females. In the HFD-Asb4-/- placenta, ID2 amounts doubled without changing the transcript levels, indicating that insulin likely increases ID2 at a level of post-transcription. In human first-trimester trophoblast HTR8/SVneo cells, exposure to insulin, but not to leptin, led to a significant increase in ID2. HFD-induced obesity markedly worsens the preeclampsia-like phenotypes in the absence of ASB4. Our data indicate that hyperinsulinemia perturbs the timely removal of ID2 and interferes with proper trophoblast differentiation, contributing to enhanced preeclampsia.
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Affiliation(s)
- Yukako Kayashima
- Department of Pathology and Laboratory Medicine, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - W. H. Davin Townley-Tilson
- Department of Pathology and Laboratory Medicine, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Neeta L. Vora
- Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Kim Boggess
- Department of Obstetrics and Gynecology, Division of Maternal Fetal Medicine, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Jonathon W. Homeister
- Department of Pathology and Laboratory Medicine, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Nobuyo Maeda-Smithies
- Department of Pathology and Laboratory Medicine, The University of North Carolina, Chapel Hill, NC 27599, USA
| | - Feng Li
- Department of Pathology and Laboratory Medicine, The University of North Carolina, Chapel Hill, NC 27599, USA
- Correspondence: ; Tel.: +1-919-966-6915; Fax: +1-919-966-8800
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Beiser T, Lisniansky E, Weitz M, Bingor A, Grad E, Rosenblum K, Thornton C, Yaka R. A functional eEF2K-eEF2 pathway in the NAc is critical for the expression of cocaine-induced psychomotor sensitisation and conditioned place preference. Transl Psychiatry 2022; 12:460. [PMID: 36319619 PMCID: PMC9626485 DOI: 10.1038/s41398-022-02232-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 10/20/2022] [Accepted: 10/24/2022] [Indexed: 01/24/2023] Open
Abstract
Recent evidence links synaptic plasticity and mRNA translation, via the eukaryotic elongation factor 2 kinase (eEF2K) and its only known substrate, eEF2. However, the involvement of the eEF2 pathway in cocaine-induced neuroadaptations and cocaine-induced behaviours is not known. Knock-in (KI) mice and shRNA were used to globally and specifically reduce eEF2K expression. Cocaine psychomotor sensitization and conditioned place preference were used to evaluate behavioural outcome. Changes in eEF2 phosphorylation were determined by western blot analyses. No effect was observed on the AMPA/NMDA receptor current ratio in the ventral tegmental area, 24 h after cocaine injection in eEF2K-KI mice compared with WT. However, development and expression of cocaine psychomotor sensitization were decreased in KI mice. Phosphorylated eEF2 was decreased one day after psychomotor sensitization and returned to baseline at seven days in the nucleus accumbens (NAc) of WT mice, but not in eEF2K-KI mice. However, one day following cocaine challenge, phosphorylated eEF2 decreased in WT but not KI mice. Importantly, specific targeting of eEF2K expression by shRNA in the NAc decreased cocaine condition place preference. These results suggest that the eEF2 pathway play a role in cocaine-induced locomotor sensitization and conditioned place preference.
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Affiliation(s)
- Tehila Beiser
- grid.9619.70000 0004 1937 0538Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Elvira Lisniansky
- grid.9619.70000 0004 1937 0538Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Moriya Weitz
- grid.9619.70000 0004 1937 0538Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Alexey Bingor
- grid.9619.70000 0004 1937 0538Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Etty Grad
- grid.9619.70000 0004 1937 0538Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Kobi Rosenblum
- grid.18098.380000 0004 1937 0562Sagol Department of Neuroscience, University of Haifa, Haifa, Israel
| | - Claire Thornton
- grid.20931.390000 0004 0425 573XDepartment of Comparative Biomedical Sciences, Royal Veterinary College, London, UK
| | - Rami Yaka
- Institute for Drug Research (IDR), School of Pharmacy, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem, Israel.
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Physiological responses and adaptations to high methane production in Japanese Black cattle. Sci Rep 2022; 12:11154. [PMID: 35778422 PMCID: PMC9249741 DOI: 10.1038/s41598-022-15146-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Accepted: 06/20/2022] [Indexed: 12/02/2022] Open
Abstract
In this study, using enteric methane emissions, we investigated the metabolic characteristics of Japanese Black cattle. Their methane emissions were measured at early (age 13 months), middle (20 months), and late fattening phases (28 months). Cattle with the highest and lowest methane emissions were selected based on the residual methane emission values, and their liver transcriptome, blood metabolites, hormones, and rumen fermentation characteristics were analyzed. Blood β-hydroxybutyric acid and insulin levels were high, whereas blood amino acid levels were low in cattle with high methane emissions. Further, propionate and butyrate levels differed depending on the enteric methane emissions. Hepatic genes, such as SERPINI2, SLC7A5, ATP6, and RRAD, which were related to amino acid transport and glucose metabolism, were upregulated or downregulated during the late fattening phase. The above mentioned metabolites and liver transcriptomes could be used to evaluate enteric methanogenesis in Japanese Black cattle.
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Bouland GA, Beulens JWJ, Nap J, van der Slik AR, Zaldumbide A, 't Hart LM, Slieker RC. Diabetes risk loci-associated pathways are shared across metabolic tissues. BMC Genomics 2022; 23:368. [PMID: 35568807 PMCID: PMC9107144 DOI: 10.1186/s12864-022-08587-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 03/23/2022] [Indexed: 11/28/2022] Open
Abstract
Aims/hypothesis Numerous genome-wide association studies have been performed to understand the influence of genetic variation on type 2 diabetes etiology. Many identified risk variants are located in non-coding and intergenic regions, which complicates understanding of how genes and their downstream pathways are influenced. An integrative data approach will help to understand the mechanism and consequences of identified risk variants. Methods In the current study we use our previously developed method CONQUER to overlap 403 type 2 diabetes risk variants with regulatory, expression and protein data to identify tissue-shared disease-relevant mechanisms. Results One SNP rs474513 was found to be an expression-, protein- and metabolite QTL. Rs474513 influenced LPA mRNA and protein levels in the pancreas and plasma, respectively. On the pathway level, in investigated tissues most SNPs linked to metabolism. However, in eleven of the twelve tissues investigated nine SNPs were linked to differential expression of the ribosome pathway. Furthermore, seven SNPs were linked to altered expression of genes linked to the immune system. Among them, rs601945 was found to influence multiple HLA genes, including HLA-DQA2, in all twelve tissues investigated. Conclusion Our results show that in addition to the classical metabolism pathways, other pathways may be important to type 2 diabetes that show a potential overlap with type 1 diabetes. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08587-5.
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Affiliation(s)
- Gerard A Bouland
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333ZC, Leiden, the Netherlands
| | - Joline W J Beulens
- Department of Epidemiology and Data Science, Amsterdam UMC, Location VUMC, Amsterdam Public Health Institute, Amsterdam, the Netherlands.,Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, the Netherlands
| | - Joey Nap
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333ZC, Leiden, the Netherlands
| | - Arno R van der Slik
- Department of Immunohematology and Blood Transfusion, Leiden University Medical Center, Leiden, The Netherlands
| | - Arnaud Zaldumbide
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333ZC, Leiden, the Netherlands
| | - Leen M 't Hart
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333ZC, Leiden, the Netherlands.,Department of Epidemiology and Data Science, Amsterdam UMC, Location VUMC, Amsterdam Public Health Institute, Amsterdam, the Netherlands.,Molecular Epidemiology Section, Department of Biomedical Data Sciences, Leiden University Medical Center, Leiden, the Netherlands
| | - Roderick C Slieker
- Department of Cell and Chemical Biology, Leiden University Medical Center, Einthovenweg 20, 2333ZC, Leiden, the Netherlands. .,Department of Epidemiology and Data Science, Amsterdam UMC, Location VUMC, Amsterdam Public Health Institute, Amsterdam, the Netherlands.
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6
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Metabolic memory determines gene expression in liver and adipose tissue of undernourished ewes. Livest Sci 2022. [DOI: 10.1016/j.livsci.2022.104949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Wei X, Yang B, Chen X, Wen L, Kan J. Zanthoxylum alkylamides ameliorate protein metabolism in type 2 diabetes mellitus rats by regulating multiple signaling pathways. Food Funct 2021; 12:3740-3753. [PMID: 33900301 DOI: 10.1039/d0fo02695f] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Type 2 diabetes mellitus (T2DM) can easily induce insulin resistance (IR) in skeletal muscle, causing protein metabolism disorder and inflammation. The present study aimed to investigate whether Zanthoxylum alkylamides (ZA) could ameliorate T2DM through regulating protein metabolism disorder by using a rat model of T2DM. The predominant bioactive constituents found in ZA were hydroxyl-α-sanshool, hydroxyl-β-sanshool and hydroxyl-γ-sanshool. The results showed that ZA improved a series of biochemical indices associated with protein metabolism and inflammation in T2DM rats. Our mechanistic finding indicated that ZA promoted protein anabolism in T2DM rats by up-regulating the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway. ZA also promoted glucose transportation in skeletal muscle to ameliorate skeletal muscle IR and energy metabolism through regulating the AMP-activated protein kinase (AMPK) signaling pathway. Moreover, ZA inhibited protein degradation and improved protein catabolism disorder in T2DM rats by down-regulating the PI3K/Akt/forkhead box O (FoxO) signaling pathway, and ZA further ameliorated inflammation to inhibit protein catabolism via regulating the tumor necrosis factor α (TNF-α)/nuclear factor κB (NF-κB) pathway in the skeletal muscle of T2DM rats. Collectively, the ameliorating effect of ZA on protein metabolism disorder in T2DM rats was the common result of regulating multiple signaling pathways. ZA decreased skeletal muscle IR to promote protein anabolism and inhibit protein catabolism for improving protein metabolism disorder, thus ultimately ameliorating T2DM. In sum, our findings demonstrated that ZA treatment could effectively ameliorate T2DM through improving protein metabolism, providing a new treatment target for T2DM.
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Affiliation(s)
- Xunyu Wei
- College of Food Science, Southwest University, 2 Tiansheng Road, Beibei, Chongqing 400715, PR China.
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8
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Wallace MA, Aguirre NW, Marcotte GR, Marshall AG, Baehr LM, Hughes DC, Hamilton KL, Roberts MN, Lopez‐Dominguez JA, Miller BF, Ramsey JJ, Baar K. The ketogenic diet preserves skeletal muscle with aging in mice. Aging Cell 2021; 20:e13322. [PMID: 33675103 PMCID: PMC8045940 DOI: 10.1111/acel.13322] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 01/11/2021] [Accepted: 01/23/2021] [Indexed: 12/20/2022] Open
Abstract
The causes of the decline in skeletal muscle mass and function with age, known as sarcopenia, are poorly understood. Nutrition (calorie restriction) interventions impact many cellular processes and increase lifespan and preserve muscle mass and function with age. As we previously observed an increase in life span and muscle function in aging mice on a ketogenic diet (KD), we aimed to investigate the effect of a KD on the maintenance of skeletal muscle mass with age and the potential molecular mechanisms of this action. Twelve‐month‐old mice were assigned to an isocaloric control or KD until 16 or 26 months of age, at which time skeletal muscle was collected for evaluating mass, morphology, and biochemical properties. Skeletal muscle mass was significantly greater at 26 months in the gastrocnemius of mice on the KD. This result in KD mice was associated with a shift in fiber type from type IIb to IIa fibers and a range of molecular parameters including increased markers of NMJ remodeling, mitochondrial biogenesis, oxidative metabolism, and antioxidant capacity, while decreasing endoplasmic reticulum (ER) stress, protein synthesis, and proteasome activity. Overall, this study shows the effectiveness of a long‐term KD in mitigating sarcopenia. The diet preferentially preserved oxidative muscle fibers and improved mitochondrial and antioxidant capacity. These adaptations may result in a healthier cellular environment, decreasing oxidative and ER stress resulting in less protein turnover. These shifts allow mice to better maintain muscle mass and function with age.
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Affiliation(s)
- Marita A. Wallace
- Department of Neurobiology, Physiology and Behavior University of California Davis CA USA
- CellMet Performance Health Perth WA Australia
| | - Nicholas W. Aguirre
- Department of Neurobiology, Physiology and Behavior University of California Davis CA USA
| | - George R. Marcotte
- Department of Neurobiology, Physiology and Behavior University of California Davis CA USA
| | - Andrea G. Marshall
- Department of Neurobiology, Physiology and Behavior University of California Davis CA USA
| | - Leslie M. Baehr
- Department of Neurobiology, Physiology and Behavior University of California Davis CA USA
| | - David C. Hughes
- Department of Neurobiology, Physiology and Behavior University of California Davis CA USA
| | - Karyn L. Hamilton
- Department of Health and Exercise Science Colorado State University Fort Collins CO USA
| | - Megan N. Roberts
- Department of Molecular Biosciences School of Veterinary Medicine University of California Davis CA USA
| | | | - Benjamin F. Miller
- Aging and Metabolism Research Program Oklahoma Medical Research Foundation Oklahoma City OK USA
| | - Jon J. Ramsey
- Department of Molecular Biosciences School of Veterinary Medicine University of California Davis CA USA
| | - Keith Baar
- Department of Neurobiology, Physiology and Behavior University of California Davis CA USA
- Department of Physiology and Membrane Biology School of Medicine University of California Davis CA USA
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Meep, a Novel Regulator of Insulin Signaling, Supports Development and Insulin Sensitivity via Maintenance of Protein Homeostasis in Drosophila melanogaster. G3-GENES GENOMES GENETICS 2020; 10:4399-4410. [PMID: 32998936 PMCID: PMC7718763 DOI: 10.1534/g3.120.401688] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Insulin signaling is critical for developmental growth and adult homeostasis, yet the downstream regulators of this signaling pathway are not completely understood. Using the model organism Drosophila melanogaster, we took a genomic approach to identify novel mediators of insulin signaling. These studies led to the identification of Meep, encoded by the gene CG32335. Expression of this gene is both insulin receptor- and diet-dependent. We found that Meep was specifically required in the developing fat body to tolerate a high-sugar diet (HSD). Meep is not essential on a control diet, but when reared on an HSD, knockdown of meep causes hyperglycemia, reduced growth, developmental delay, pupal lethality, and reduced longevity. These phenotypes stem in part from Meep’s role in promoting insulin sensitivity and protein stability. This work suggests a critical role for protein homeostasis in development during overnutrition. Because Meep is conserved and obesity-associated in mammals, future studies on Meep may help to understand the role of proteostasis in insulin-resistant type 2 diabetes.
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Abstract
Vitamin D receptor expression and associated function have been reported in various muscle models, including C2C12, L6 cell lines and primary human skeletal muscle cells. It is believed that 1,25-hydroxyvitamin D3 (1,25(OH)2D3), the active form of vitamin D, has a direct regulatory role in skeletal muscle function, where it participates in myogenesis, cell proliferation, differentiation, regulation of protein synthesis and mitochondrial metabolism through activation of various cellular signalling cascades, including the mitogen-activated protein kinase pathway(s). It has also been suggested that 1,25(OH)2D3 and its associated receptor have genomic targets, resulting in regulation of gene expression, as well as non-genomic functions that can alter cellular behaviour through binding and modification of targets not directly associated with transcriptional regulation. The molecular mechanisms of vitamin D signalling, however, have not been fully clarified. Vitamin D inadequacy or deficiency is associated with muscle fibre atrophy, increased risk of chronic musculoskeletal pain, sarcopenia and associated falls, and may also decrease RMR. The main purpose of the present review is to describe the molecular role of vitamin D in skeletal muscle tissue function and metabolism, specifically in relation to proliferation, differentiation and protein synthesis processes. In addition, the present review also includes discussion of possible genomic and non-genomic pathways of vitamin D action.
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de Proença ARG, Pereira KD, Meneguello L, Tamborlin L, Luchessi AD. Insulin action on protein synthesis and its association with eIF5A expression and hypusination. Mol Biol Rep 2019; 46:587-596. [PMID: 30519811 DOI: 10.1007/s11033-018-4512-1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 11/19/2018] [Indexed: 12/20/2022]
Abstract
The hormone insulin plays a central role in the metabolism of carbohydrates, lipids, and proteins. In relation to protein metabolism, insulin stimulates amino acid uptake and activates protein synthesis in responsive cells by modulation of signal transduction pathways, such as associated to Akt/PkB, mTOR, S6Ks, 4E-BP1, and several translation initiation/elongation factors. In this context, there is no information on direct cellular treatment with insulin and effects on eukaryotic translation initiation factor 5A (eIF5A) regulation. The eIF5A protein contains an exclusive amino acid residue denominated hypusine, which is essential for its activity and synthesized by posttranslational modification of a specific lysine residue using spermidine as substrate. The eIF5A protein is involved in cellular proliferation and differentiation processes, as observed for satellite cells derived from rat muscles, revealing that eIF5A has an important role in muscle regeneration. The aim of this study was to determine whether eIF5A expression and hypusination are influenced by direct treatment of insulin on L6 myoblast cells. We observed that insulin increased the content of eIF5A transcripts. This effect occurred in cells treated or depleted of fetal bovine serum, revealing a positive insulin effect independent of other serum components. In addition, it was observed that hypusination follows the maintenance of eIF5A protein content in the serum depleted cells and treated with insulin. These results demonstrate that eIF5A is modulated by insulin, contributing the protein synthesis machinery control, as observed by puromycin incorporation in nascent proteins.
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Affiliation(s)
| | - Karina Danielle Pereira
- Laboratory of Biotechnology, School of Applied Sciences, University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
- Institute of Biosciences, São Paulo State University (UNESP), Rio Claro, São Paulo, Brazil
| | - Leticia Meneguello
- Laboratory of Biotechnology, School of Applied Sciences, University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
- Institute of Biosciences, São Paulo State University (UNESP), Rio Claro, São Paulo, Brazil
| | - Leticia Tamborlin
- Laboratory of Biotechnology, School of Applied Sciences, University of Campinas (UNICAMP), Limeira, São Paulo, Brazil
- Institute of Biosciences, São Paulo State University (UNESP), Rio Claro, São Paulo, Brazil
| | - Augusto Ducati Luchessi
- Laboratory of Biotechnology, School of Applied Sciences, University of Campinas (UNICAMP), Limeira, São Paulo, Brazil.
- Institute of Biosciences, São Paulo State University (UNESP), Rio Claro, São Paulo, Brazil.
- Laboratório de Biotecnologia, Faculdade de Ciências Aplicadas, Universidade Estadual de Campinas, Rua Pedro Zaccaria, 1300, Limeira, São Paulo, 13484-350, Brazil.
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Wu M, Obara Y, Ohshima S, Nagasawa Y, Ishii K. Insulin treatment augments KCNQ1/KCNE1 currents but not KCNQ1 currents, which is associated with an increase in KCNE1 expression. Biochem Biophys Res Commun 2017; 493:409-415. [PMID: 28882596 DOI: 10.1016/j.bbrc.2017.09.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2017] [Accepted: 09/03/2017] [Indexed: 11/25/2022]
Abstract
Diabetes mellitus affects ion channel physiology. We have previously reported that acute application of insulin suppresses the KCNQ1/KCNE1 currents that play an important role in terminating ventricular action potential. In this study, we investigated the effect of long-term insulin treatment on KCNQ1/KCNE1 currents using the Xenopus oocyte expression system. Insulin treatment with a duration longer than 6 h had an opposite effect to acute insulin application, that is, it augmented the KCNQ1/KCNE1 currents. Inhibitors of PI3K, wortmannin and LY294002, and a MEK inhibitor, U0126, abolished the potentiating effect of long-term insulin treatment. The long-term treatment with insulin had no effect on KCNQ1 currents indicating an essential role of KCNE1 in the insulin effect, which is similar to the acute insulin effect. Cycloheximide, an inhibitor of protein synthesis, and brefeldin A, an inhibitor of protein transport from endoplasmic reticulum, suppressed the long-term insulin effect. Western blotting analysis combined with these pharmacological data suggest that long-term insulin treatment augments KCNQ1/KCNE1 currents by increasing KCNE1 protein expression.
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Affiliation(s)
- Minghua Wu
- Department of Pharmacology, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata 990-9585, Japan
| | - Yutaro Obara
- Department of Pharmacology, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata 990-9585, Japan
| | - Shingo Ohshima
- Department of Pharmacology, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata 990-9585, Japan
| | - Yoshinobu Nagasawa
- Department of Pharmacology and Therapeutics, Faculty of Pharmaceutical Sciences, Toho University, Chiba 274-8510, Japan
| | - Kuniaki Ishii
- Department of Pharmacology, Yamagata University School of Medicine, 2-2-2 Iida-nishi, Yamagata 990-9585, Japan.
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Mohl BP, Emmott E, Roy P. Phosphoproteomic Analysis Reveals the Importance of Kinase Regulation During Orbivirus Infection. Mol Cell Proteomics 2017; 16:1990-2005. [PMID: 28851738 PMCID: PMC5672004 DOI: 10.1074/mcp.m117.067355] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 08/08/2017] [Indexed: 01/03/2023] Open
Abstract
Bluetongue virus (BTV) causes infections in wild and domesticated ruminants with high morbidity and mortality and is responsible for significant economic losses in both developing and developed countries. BTV serves as a model for the study of other members of the Orbivirus genus. Previously, the importance of casein kinase 2 for BTV replication was demonstrated. To identify intracellular signaling pathways and novel host-cell kinases involved during BTV infection, the phosphoproteome of BTV infected cells was analyzed. Over 1000 phosphosites were identified using mass spectrometry, which were then used to determine the corresponding kinases involved during BTV infection. This analysis yielded protein kinase A (PKA) as a novel kinase activated during BTV infection. Subsequently, the importance of PKA for BTV infection was validated using a PKA inhibitor and activator. Our data confirmed that PKA was essential for efficient viral growth. Further, we showed that PKA is also required for infection of equid cells by African horse sickness virus, another member of the Orbivirus genus. Thus, despite their preference in specific host species, orbiviruses may utilize the same host signaling pathways during their replication.
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Affiliation(s)
- Bjorn-Patrick Mohl
- From the ‡Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK
| | - Edward Emmott
- §University of Cambridge, Division of Virology, Department of Pathology, Lab block level 5, Box 237, Addenbrookes Hospital, Cambridge, UK
| | - Polly Roy
- From the ‡Department of Pathogen Molecular Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, Keppel Street, London, WC1E 7HT, UK;
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Tsuchida W, Iwata M, Akimoto T, Matsuo S, Asai Y, Suzuki S. Heat Stress Modulates Both Anabolic and Catabolic Signaling Pathways Preventing Dexamethasone-Induced Muscle Atrophy In Vitro. J Cell Physiol 2017; 232:650-664. [PMID: 27649272 PMCID: PMC5132157 DOI: 10.1002/jcp.25609] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2016] [Accepted: 09/19/2016] [Indexed: 12/29/2022]
Abstract
It is generally recognized that synthetic glucocorticoids induce skeletal muscle weakness, and endogenous glucocorticoid levels increase in patients with muscle atrophy. It is reported that heat stress attenuates glucocorticoid-induced muscle atrophy; however, the mechanisms involved are unknown. Therefore, we examined the mechanisms underlying the effects of heat stress against glucocorticoid-induced muscle atrophy using C2C12 myotubes in vitro, focusing on expression of key molecules and signaling pathways involved in regulating protein synthesis and degradation. The synthetic glucocorticoid dexamethasone decreased myotube diameter and protein content, and heat stress prevented the morphological and biochemical glucocorticoid effects. Heat stress also attenuated increases in mRNAs of regulated in development and DNA damage responses 1 (REDD1) and Kruppel-like factor 15 (KLF15). Heat stress recovered the dexamethasone-induced inhibition of PI3K/Akt signaling. These data suggest that changes in anabolic and catabolic signals are involved in heat stress-induced protection against glucocorticoid-induced muscle atrophy. These results have a potentially broad clinical impact because elevated glucocorticoid levels are implicated in a wide range of diseases associated with muscle wasting. J. Cell. Physiol. 232: 650-664, 2017. © 2016 The Authors. Journal of Cellular Physiology published by Wiley Periodicals, Inc.
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Affiliation(s)
- Wakako Tsuchida
- Department of RehabilitationFaculty of Health SciencesNihon Fukushi UniversityHandaAichiJapan
- Program in Physical and Occupational TherapyGraduate School of MedicineNagoya UniversityNagoyaAichiJapan
| | - Masahiro Iwata
- Department of RehabilitationFaculty of Health SciencesNihon Fukushi UniversityHandaAichiJapan
- Program in Physical and Occupational TherapyGraduate School of MedicineNagoya UniversityNagoyaAichiJapan
| | - Takayuki Akimoto
- Faculty of Sport SciencesWaseda UniversityTokorozawaSaitamaJapan
| | - Shingo Matsuo
- Department of RehabilitationFaculty of Health SciencesNihon Fukushi UniversityHandaAichiJapan
- Program in Physical and Occupational TherapyGraduate School of MedicineNagoya UniversityNagoyaAichiJapan
| | - Yuji Asai
- Department of RehabilitationFaculty of Health SciencesNihon Fukushi UniversityHandaAichiJapan
| | - Shigeyuki Suzuki
- Program in Physical and Occupational TherapyGraduate School of MedicineNagoya UniversityNagoyaAichiJapan
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15
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Bond P. Regulation of mTORC1 by growth factors, energy status, amino acids and mechanical stimuli at a glance. J Int Soc Sports Nutr 2016; 13:8. [PMID: 26937223 PMCID: PMC4774173 DOI: 10.1186/s12970-016-0118-y] [Citation(s) in RCA: 76] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 02/18/2016] [Indexed: 12/05/2022] Open
Abstract
The mechanistic/mammalian target of rapamycin complex 1 (mTORC1) plays a pivotal role in the regulation of skeletal muscle protein synthesis. Activation of the complex leads to phosphorylation of two important sets of substrates, namely eIF4E binding proteins and ribosomal S6 kinases. Phosphorylation of these substrates then leads to an increase in protein synthesis, mainly by enhancing translation initiation. mTORC1 activity is regulated by several inputs, such as growth factors, energy status, amino acids and mechanical stimuli. Research in this field is rapidly evolving and unraveling how these inputs regulate the complex. Therefore this review attempts to provide a brief and up-to-date narrative on the regulation of this marvelous protein complex. Additionally, some sports supplements which have been shown to regulate mTORC1 activity are discussed.
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Affiliation(s)
- Peter Bond
- PeterBond.nl, Waterhoenlaan 25, Zeist, Netherlands
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16
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Rivas DA, McDonald DJ, Rice NP, Haran PH, Dolnikowski GG, Fielding RA. Diminished anabolic signaling response to insulin induced by intramuscular lipid accumulation is associated with inflammation in aging but not obesity. Am J Physiol Regul Integr Comp Physiol 2016; 310:R561-9. [PMID: 26764052 DOI: 10.1152/ajpregu.00198.2015] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 01/11/2016] [Indexed: 12/24/2022]
Abstract
The loss of skeletal muscle mass is observed in many pathophysiological conditions, including aging and obesity. The loss of muscle mass and function with aging is defined as sarcopenia and is characterized by a mismatch between skeletal muscle protein synthesis and breakdown. Characteristic metabolic features of both aging and obesity are increases in intramyocellular lipid (IMCL) content in muscle. IMCL accumulation may play a mechanistic role in the development of anabolic resistance and the progression of muscle atrophy in aging and obesity. In the present study, aged and high-fat fed mice were used to determine mechanisms leading to muscle loss. We hypothesized the accumulation of bioactive lipids in skeletal muscle, such as ceramide or diacylglycerols, leads to insulin resistance with aging and obesity and the inability to activate protein synthesis, contributing to skeletal muscle loss. We report a positive association between bioactive lipid accumulation and the loss of lean mass and muscle strength. Obese and aged animals had significantly higher storage of ceramide and diacylglycerol compared with young. Furthermore, there was an attenuated insulin response in components of the mTOR anabolic signaling pathway. We also observed differential increases in the expression of inflammatory cytokines and the phosphorylation of IκBα with aging and obesity. These data challenge the accepted role of increased inflammation in obesity-induced insulin resistance in skeletal muscle. Furthermore, we have now established IκBα with a novel function in aging-associated muscle loss that may be independent of its previously understood role as an NF-κB inhibitor.
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Affiliation(s)
- Donato A Rivas
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
| | - Devin J McDonald
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
| | - Nicholas P Rice
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
| | - Prashanth H Haran
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
| | - Gregory G Dolnikowski
- Mass Spectrometry Unit; Jean Mayer U.S. Department of Agriculture, Human Nutrition Research Center on Aging, Tufts University, Boston, Massachusetts
| | - Roger A Fielding
- Nutrition, Exercise Physiology and Sarcopenia Laboratory, Tufts University, Boston, Massachusetts; and
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17
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Trommelen J, Groen BBL, Hamer HM, de Groot LCPGM, van Loon LJC. MECHANISMS IN ENDOCRINOLOGY: Exogenous insulin does not increase muscle protein synthesis rate when administered systemically: a systematic review. Eur J Endocrinol 2015; 173:R25-34. [PMID: 25646407 DOI: 10.1530/eje-14-0902] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 02/02/2015] [Indexed: 01/07/2023]
Abstract
BACKGROUND Though it is well appreciated that insulin plays an important role in the regulation of muscle protein metabolism, there is much discrepancy in the literature on the capacity of exogenous insulin administration to increase muscle protein synthesis rates in vivo in humans. OBJECTIVE To assess whether exogenous insulin administration increases muscle protein synthesis rates in young and older adults. DESIGN A systematic review of clinical trials was performed and the presence or absence of an increase in muscle protein synthesis rate was reported for each individual study arm. In a stepwise manner, multiple models were constructed that excluded study arms based on the following conditions: model 1, concurrent hyperaminoacidemia; model 2, insulin-induced hypoaminoacidemia; model 3, supraphysiological insulin concentrations; and model 4, older, more insulin resistant, subjects. CONCLUSIONS From the presented data in the current systematic review, we conclude that: i) exogenous insulin and amino acid administration effectively increase muscle protein synthesis, but this effect is attributed to the hyperaminoacidemia; ii) exogenous insulin administered systemically induces hypoaminoacidemia which obviates any insulin-stimulatory effect on muscle protein synthesis; iii) exogenous insulin resulting in supraphysiological insulin levels exceeding 50, 000 pmol/l may effectively augment muscle protein synthesis; iv) exogenous insulin may have a diminished effect on muscle protein synthesis in older adults due to age-related anabolic resistance; and v) exogenous insulin administered systemically does not increase muscle protein synthesis in healthy, young adults.
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Affiliation(s)
- Jorn Trommelen
- Department of Human Movement SciencesFaculty of Health, Medicine and Life Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, PO Box 616, 6200 MD Maastricht, The NetherlandsDivision of Human NutritionWageningen University, Wageningen, The Netherlands
| | - Bart B L Groen
- Department of Human Movement SciencesFaculty of Health, Medicine and Life Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, PO Box 616, 6200 MD Maastricht, The NetherlandsDivision of Human NutritionWageningen University, Wageningen, The Netherlands
| | - Henrike M Hamer
- Department of Human Movement SciencesFaculty of Health, Medicine and Life Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, PO Box 616, 6200 MD Maastricht, The NetherlandsDivision of Human NutritionWageningen University, Wageningen, The Netherlands
| | - Lisette C P G M de Groot
- Department of Human Movement SciencesFaculty of Health, Medicine and Life Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, PO Box 616, 6200 MD Maastricht, The NetherlandsDivision of Human NutritionWageningen University, Wageningen, The Netherlands
| | - Luc J C van Loon
- Department of Human Movement SciencesFaculty of Health, Medicine and Life Sciences, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University, PO Box 616, 6200 MD Maastricht, The NetherlandsDivision of Human NutritionWageningen University, Wageningen, The Netherlands
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18
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Caruso M, Ma D, Msallaty Z, Lewis M, Seyoum B, Al-janabi W, Diamond M, Abou-Samra AB, Højlund K, Tagett R, Draghici S, Zhang X, Horowitz JF, Yi Z. Increased interaction with insulin receptor substrate 1, a novel abnormality in insulin resistance and type 2 diabetes. Diabetes 2014; 63:1933-47. [PMID: 24584551 PMCID: PMC4030113 DOI: 10.2337/db13-1872] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Insulin receptor substrate 1 (IRS1) is a key mediator of insulin signal transduction. Perturbations involving IRS1 complexes may lead to the development of insulin resistance and type 2 diabetes (T2D). Surprisingly little is known about the proteins that interact with IRS1 in humans under health and disease conditions. We used a proteomic approach to assess IRS1 interaction partners in skeletal muscle from lean healthy control subjects (LCs), obese insulin-resistant nondiabetic control subjects (OCs), and participants with T2D before and after insulin infusion. We identified 113 novel endogenous IRS1 interaction partners, which represents the largest IRS1 interactome in humans and provides new targets for studies of IRS1 complexes in various diseases. Furthermore, we generated the first global picture of IRS1 interaction partners in LCs, and how they differ in OCs and T2D patients. Interestingly, dozens of proteins in OCs and/or T2D patients exhibited increased associations with IRS1 compared with LCs under the basal and/or insulin-stimulated conditions, revealing multiple new dysfunctional IRS1 pathways in OCs and T2D patients. This novel abnormality, increased interaction of multiple proteins with IRS1 in obesity and T2D in humans, provides new insights into the molecular mechanism of insulin resistance and identifies new targets for T2D drug development.
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Affiliation(s)
- Michael Caruso
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI
| | - Danjun Ma
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI
| | - Zaher Msallaty
- Division of Endocrinology, Wayne State University School of Medicine, Wayne State University, Detroit, MI
| | - Monique Lewis
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI
| | - Berhane Seyoum
- Division of Endocrinology, Wayne State University School of Medicine, Wayne State University, Detroit, MI
| | - Wissam Al-janabi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI
| | - Michael Diamond
- Department of Obstetrics and Gynecology, Wayne State University, Detroit, MIDepartment of Obstetrics and Gynecology, Georgia Regents University, Augusta, GA
| | - Abdul B Abou-Samra
- Division of Endocrinology, Wayne State University School of Medicine, Wayne State University, Detroit, MIDepartment of Medicine, Hamad Medical Corporation, Doha, Qatar
| | - Kurt Højlund
- Diabetes Research Centre, Department of Endocrinology, Odense University Hospital, Odense, Denmark
| | - Rebecca Tagett
- Department of Computer Science, College of Engineering, Wayne State University, Detroit, MI
| | - Sorin Draghici
- Department of Computer Science, College of Engineering, Wayne State University, Detroit, MI
| | - Xiangmin Zhang
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI
| | | | - Zhengping Yi
- Department of Pharmaceutical Sciences, Eugene Applebaum College of Pharmacy/Health Sciences, Wayne State University, Detroit, MI
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19
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El Osta M, Liu M, Adada M, Senkal CE, Idkowiak-Baldys J, Obeid LM, Clarke CJ, Hannun YA. Sustained PKCβII activity confers oncogenic properties in a phospholipase D- and mTOR-dependent manner. FASEB J 2013; 28:495-505. [PMID: 24121461 DOI: 10.1096/fj.13-230557] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Protein kinase C (PKC) is a family of serine/threonine kinases implicated in a variety of physiological processes. We have shown previously that sustained activation of the classical PKCα and PKCβII induces their phospholipase D (PLD)-dependent internalization and translocation to a subset of the recycling endosomes defined by the presence of PKC and PLD (the pericentrion), which results in significant differences in phosphorylation of PKC substrates. Here, we have investigated the biological consequences of sustained PKC activity and the involvement of PLD in this process. We find that sustained activation of PKC results in activation of the mammalian target of rapamycin (mTOR)/S6 kinase pathway in a PLD- and endocytosis-dependent manner, with both pharmacologic inhibitors and siRNA implicating the PLD2 isoform. Notably, dysregulated overexpression of PKCβII in A549 lung cancer cells was necessary for the enhanced proliferation and migration of these cancer cells. Inhibition of PKCβII with enzastaurin reduced A549 cell proliferation by >60% (48 h) and migration by >50%. These biological effects also required both PLD activity and mTOR function, with both the PLD inhibitor FIPI and rapamycin reducing cell growth by >50%. Reciprocally, forced overexpression of wild-type PKCβII, but not an F666D mutant that cannot interact with PLD, was sufficient to enhance cell growth and increase migration of noncancerous HEK cells; indeed, both properties were almost doubled when compared to vector control and PKC-F666D-overexpressing cells. Notably, this condition was also dependent on both PLD and mTOR activity. In summary, these data define a PKC-driven oncogenic signaling pathway that requires both PLD and mTOR, and suggest that inhibitors of PLD or mTOR would be beneficial in cancers where PKC overexpression is a contributing or driving factor.
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Affiliation(s)
- Mohamad El Osta
- 2Stony Brook Cancer Center and Department of Medicine, Stony Brook University, 100 Nicolls Rd., Stony Brook, NY 11794, USA.
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20
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Salles J, Chanet A, Giraudet C, Patrac V, Pierre P, Jourdan M, Luiking YC, Verlaan S, Migné C, Boirie Y, Walrand S. 1,25(OH)2
-vitamin D3
enhances the stimulating effect of leucine and insulin on protein synthesis rate through Akt/PKB and mTOR mediated pathways in murine C2C12 skeletal myotubes. Mol Nutr Food Res 2013; 57:2137-46. [DOI: 10.1002/mnfr.201300074] [Citation(s) in RCA: 124] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2013] [Revised: 04/22/2013] [Accepted: 05/28/2013] [Indexed: 12/11/2022]
Affiliation(s)
- Jérôme Salles
- Clermont Université; Université d'Auvergne, Unité de Nutrition Humaine; Clermont-Ferrand France
- INRA, UMR 1019, UNH, CRNH Auvergne; Clermont-Ferrand France
| | - Audrey Chanet
- Clermont Université; Université d'Auvergne, Unité de Nutrition Humaine; Clermont-Ferrand France
- INRA, UMR 1019, UNH, CRNH Auvergne; Clermont-Ferrand France
| | - Christophe Giraudet
- Clermont Université; Université d'Auvergne, Unité de Nutrition Humaine; Clermont-Ferrand France
- INRA, UMR 1019, UNH, CRNH Auvergne; Clermont-Ferrand France
| | - Véronique Patrac
- Clermont Université; Université d'Auvergne, Unité de Nutrition Humaine; Clermont-Ferrand France
- INRA, UMR 1019, UNH, CRNH Auvergne; Clermont-Ferrand France
| | - Philippe Pierre
- Centre d'Immunologie de Marseille-Luminy; Aix-Marseille Université; Marseille France
- Institut National de la Santé et de la Recherche Médicale; U1104, Marseille France
- Centre National de la Recherche Scientifique; UMR 7280 Marseille France
| | | | | | | | - Carole Migné
- Clermont Université; Université d'Auvergne, Unité de Nutrition Humaine; Clermont-Ferrand France
- INRA, UMR 1019, UNH, CRNH Auvergne; Clermont-Ferrand France
| | - Yves Boirie
- Clermont Université; Université d'Auvergne, Unité de Nutrition Humaine; Clermont-Ferrand France
- INRA, UMR 1019, UNH, CRNH Auvergne; Clermont-Ferrand France
- CHU Clermont-Ferrand; Service de Nutrition Clinique; Clermont-Ferrand France
| | - Stéphane Walrand
- Clermont Université; Université d'Auvergne, Unité de Nutrition Humaine; Clermont-Ferrand France
- INRA, UMR 1019, UNH, CRNH Auvergne; Clermont-Ferrand France
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21
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Ishizuka Y, Kakiya N, Witters LA, Oshiro N, Shirao T, Nawa H, Takei N. AMP-activated protein kinase counteracts brain-derived neurotrophic factor-induced mammalian target of rapamycin complex 1 signaling in neurons. J Neurochem 2013; 127:66-77. [PMID: 23841933 DOI: 10.1111/jnc.12362] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Revised: 07/04/2013] [Accepted: 07/05/2013] [Indexed: 12/20/2022]
Abstract
Growth factors and nutrients, such as amino acids and glucose, regulate mammalian target of rapamycin complex 1 (mTORC1) signaling and subsequent translational control in a coordinated manner. Brain-derived neurotrophic factor (BDNF), the most prominent neurotrophic factor in the brain, activates mTORC1 and induces phosphorylation of its target, p70S6 kinase (p70S6K), at Thr389 in neurons. BDNF also increases mammalian target of rapamycin-dependent novel protein synthesis in neurons. Here, we report that BDNF-induced p70S6K activation is dependent on glucose, but not amino acids, sufficiency in cultured cortical neurons. AMP-activated protein kinase (AMPK) is the molecular background to this specific nutrient dependency. Activation of AMPK, which is induced by glucose deprivation, treatment with pharmacological agents such as 2-deoxy-D-glucose, metformin, and 5-aminoimidazole-4-carboxamide ribonucleoside or forced expression of a constitutively active AMPKα subunit, counteracts BDNF-induced phosphorylation of p70S6K and enhanced protein synthesis in cortical neurons. These results indicate that AMPK inhibits the effects of BDNF on mTORC1-mediated translation in neurons.
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Affiliation(s)
- Yuta Ishizuka
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan; Department of Neurobiology and Behavior, Gunma University Graduate School of Medicine, Gunma, Japan
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22
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Creatinine and insulin predict cardiac mass in drug-naïve hypertensive patients. Int J Cardiol 2013; 167:519-24. [DOI: 10.1016/j.ijcard.2012.01.077] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Revised: 10/18/2011] [Accepted: 01/22/2012] [Indexed: 11/21/2022]
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23
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Kwan HT, Chan DW, Cai PCH, Mak CSL, Yung MMH, Leung THY, Wong OGW, Cheung ANY, Ngan HYS. AMPK activators suppress cervical cancer cell growth through inhibition of DVL3 mediated Wnt/β-catenin signaling activity. PLoS One 2013; 8:e53597. [PMID: 23301094 PMCID: PMC3534705 DOI: 10.1371/journal.pone.0053597] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Accepted: 11/30/2012] [Indexed: 12/18/2022] Open
Abstract
Recent evidence has suggested that AMPK activators may be applied as therapeutic drugs in suppressing cancer cell growth. However, the molecular mechanism of their suppressive function in cancer cells is still unclear. Here we show that AMPK activators impair cervical cancer cell growth through the reduction of DVL3, a positive regulator in Wnt/β-catenin signaling and an oncogenic player in cervical cancer tumorigenesis. By western blot and immunohistochemical analyses, we demonstrated that DVL3 was frequently upregulated and significantly associated with elevated β-catenin (P = 0.009) and CyclinD1 (P = 0.009) expressions in cervical cancer. Enforced expression of DVL3 elevated β-catenin and augmented cervical cancer cell growth, verifying that DVL3-mediated Wnt/β-catenin activation is involved in cervical cancer oncogenesis. On the other aspect, we noted that the cervical cancer cell growth was remarkably suppressed by AMPK activators and such cell growth inhibition was in concomitant with the reduction of DVL3 protein level in dose- and time-dependent manners. Besides, impaired mTOR signaling activity also reduced DVL3 expression. In contrast, co-treatment with Compound C (AMPK inhibitor) could significantly abrogate metformin induced DVL3 reduction. In addition, co-treatment with AM114 or MG132 (proteosomal inhibitors) could partially restore DVL3 expression under the treatment of metformin. Further in vivo ubiquitination assay revealed that metformin could reduce DVL3 by ubiquitin/proteasomal degradation. To our knowledge, this is the first report showing the probable molecular mechanisms of that the AMPK activators suppress cervical cancer cell growth by impairing DVL3 protein synthesis via AMPK/mTOR signaling and/or partially promoting the proteasomal degradation of DVL3.
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Affiliation(s)
- H. T. Kwan
- Departments of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P. R. China
| | - David W. Chan
- Departments of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P. R. China
- * E-mail: (HYSN); (DWC)
| | - Patty C. H. Cai
- Departments of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P. R. China
| | - Celia S. L. Mak
- Departments of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P. R. China
| | - Mingo M. H. Yung
- Departments of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P. R. China
| | - Thomas H. Y. Leung
- Departments of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P. R. China
| | - Oscar G. W. Wong
- Department of Pathology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P. R. China
| | - Annie N. Y. Cheung
- Department of Pathology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P. R. China
| | - Hextan Y. S. Ngan
- Departments of Obstetrics and Gynaecology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, P. R. China
- * E-mail: (HYSN); (DWC)
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24
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Schwer CI, Stoll P, Rospert S, Fitzke E, Schallner N, Bürkle H, Schmidt R, Humar M. Carbon monoxide releasing molecule-2 CORM-2 represses global protein synthesis by inhibition of eukaryotic elongation factor eEF2. Int J Biochem Cell Biol 2012; 45:201-12. [PMID: 23041477 DOI: 10.1016/j.biocel.2012.09.020] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Revised: 08/16/2012] [Accepted: 09/25/2012] [Indexed: 01/04/2023]
Abstract
Carbon monoxide (CO) is an endogenous gaseous transmitter that exerts antiproliferative effects in many cell types, but effects of CO on the translational machinery are not described. We examined the effects of the carbon monoxide releasing molecule-2 (CORM-2) on critical steps in translational signaling and global protein synthesis in pancreatic stellate cells (PSCs), the most prominent collagen-producing cells in the pancreas, whose activation is associated with pancreatic fibrosis. PSCs were isolated from rat pancreatic tissue and incubated with CORM-2. CORM-2 prevented the decrease in the phosphorylation of eukaryotic elongation factor 2 (eEF2) caused by serum. By contrast, the activation dependent phosphorylation of initiation factor 4E-binding protein 1 (4E-BP1) was inhibited by CORM-2 treatment. The phosphorylation of eukaryotic initiation factor 2α (eIF2α) and eukaryotic initiation factor 4E (eIF4E) were not affected by CORM-2 treatment. In consequence, CORM-2 mediated eEF2 phosphorylation and inactivation of 4E-BP1 suppressed global protein synthesis. These observations were associated with inhibition of phosphatidylinositol 3-kinase-Akt-mammalian target of rapamycin (PI3K-Akt-mTOR) signaling and increased intracellular calcium and cAMP levels. The CORM-2 mediated inhibition of protein synthesis resulted in downregulation of cyclin D1 and cyclin E expression, a subsequent decline in the phosphorylation of the retinoblastoma tumor suppressor protein (Rb) and cell growth arrest at the G(0)/G(1) phase checkpoint of the cell cycle. Our results suggest the therapeutic application of CO releasing molecules such as CORM-2 for the treatment of fibrosis, inflammation, cancer, or other pathologic states associated with excessive protein synthesis or hyperproliferation. However, prolonged exogenous application of CO might also have negative effects on cellular protein homeostasis.
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Affiliation(s)
- Christian Ingo Schwer
- Department of Anesthesiology and Critical Care Medicine, University Medical Center Freiburg, Hugstetterstrasse 55, D-79106 Freiburg, Germany.
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25
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Scherp P, Putluri N, LeBlanc GJ, Wang ZQ, Zhang XH, Yu Y, Ribnicky D, Cefalu WT, Kheterpal I. Proteomic analysis reveals cellular pathways regulating carbohydrate metabolism that are modulated in primary human skeletal muscle culture due to treatment with bioactives from Artemisia dracunculus L. J Proteomics 2012; 75:3199-210. [PMID: 22480907 DOI: 10.1016/j.jprot.2012.03.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2011] [Revised: 03/14/2012] [Accepted: 03/16/2012] [Indexed: 12/25/2022]
Abstract
Insulin resistance is a major pathophysiologic abnormality that characterizes metabolic syndrome and type 2 diabetes. A well characterized ethanolic extract of Artemisia dracunculus L., termed PMI 5011, has been shown to improve insulin action in vitro and in vivo, but the cellular mechanisms remain elusive. Using differential proteomics, we have studied mechanisms by which PMI 5011 enhances insulin action in primary human skeletal muscle culture obtained by biopsy from obese, insulin-resistant individuals. Using iTRAQ™ labeling and LC-MS/MS, we have identified over 200 differentially regulated proteins due to treatment with PMI 5011 and insulin stimulation. Bioinformatics analyses determined that several metabolic pathways related to glycolysis, glucose transport and cell signaling were highly represented and differentially regulated in the presence of PMI 5011 indicating that this extract affects several pathways modulating carbohydrate metabolism, including translocation of GLUT4 to the plasma membrane. These findings provide a molecular mechanism by which a botanical extract improves insulin stimulated glucose uptake, transport and metabolism at the cellular level resulting in enhanced whole body insulin sensitivity.
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Affiliation(s)
- Peter Scherp
- Protein Structural Biology, Pennington Biomedical Research Center, Louisiana State University System, 6400 Perkins Road, Baton Rouge, LA 70808, USA
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Adeli K. Translational control mechanisms in metabolic regulation: critical role of RNA binding proteins, microRNAs, and cytoplasmic RNA granules. Am J Physiol Endocrinol Metab 2011; 301:E1051-64. [PMID: 21971522 DOI: 10.1152/ajpendo.00399.2011] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Regulated cell metabolism involves acute and chronic regulation of gene expression by various nutritional and endocrine stimuli. To respond effectively to endogenous and exogenous signals, cells require rapid response mechanisms to modulate transcript expression and protein synthesis and cannot, in most cases, rely on control of transcriptional initiation that requires hours to take effect. Thus, co- and posttranslational mechanisms have been increasingly recognized as key modulators of metabolic function. This review highlights the critical role of mRNA translational control in modulation of global protein synthesis as well as specific protein factors that regulate metabolic function. First, the complex lifecycle of eukaryotic mRNAs will be reviewed, including our current understanding of translational control mechanisms, regulation by RNA binding proteins and microRNAs, and the role of RNA granules, including processing bodies and stress granules. Second, the current evidence linking regulation of mRNA translation with normal physiological and metabolic pathways and the associated disease states are reviewed. A growing body of evidence supports a key role of translational control in metabolic regulation and implicates translational mechanisms in the pathogenesis of metabolic disorders such as type 2 diabetes. The review also highlights translational control of apolipoprotein B (apoB) mRNA by insulin as a clear example of endocrine modulation of mRNA translation to bring about changes in specific metabolic pathways. Recent findings made on the role of 5'-untranslated regions (5'-UTR), 3'-UTR, RNA binding proteins, and RNA granules in mediating insulin regulation of apoB mRNA translation, apoB protein synthesis, and hepatic lipoprotein production are discussed.
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Affiliation(s)
- Khosrow Adeli
- Program in Molecular Structure & Function, Research Institute, The Hospital for Sick Children, Atrium 3653, 555 University Ave., Toronto, ON, M5G 1X8 Canada.
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Perez-Leal O, Merali S. Regulation of polyamine metabolism by translational control. Amino Acids 2011; 42:611-7. [PMID: 21811825 DOI: 10.1007/s00726-011-1036-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 05/25/2011] [Indexed: 12/18/2022]
Abstract
Polyamines are low molecular weight, positively charged compounds that are ubiquitous in all living cells. They play a crucial role in many biochemical processes including regulation of transcription and translation, modulation of enzyme activities, regulation of ion channels and apoptosis. A strict balance between synthesis, catabolism and excretion tightly controls the cellular concentration of polyamines. The concentrations of rate-limiting enzymes in the polyamine synthesis and degradation pathways are regulated at different levels, including transcription, translation and degradation. Polyamines can modulate the translation of most of the enzymes required for their synthesis and catabolism through feedback mechanisms that are unique for each enzyme. Translational control is associated with cis-acting and trans-acting factors that can be influenced by the concentration of polyamines through mechanisms that are not completely understood. In this review, we present an overview of the translational control mechanisms of the proteins in the polyamine pathway, including ornithine decarboxylase (ODC), ODC antizyme, S-adenosylmethionine decarboxylase and spermidine/spermine N(1) acetyltransferase, highlighting the areas where more research is needed. A better understanding of the translational control of these enzymes would offer the possibility of a novel pharmacological intervention against cancer and other diseases.
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Affiliation(s)
- Oscar Perez-Leal
- AHB/552, Department of Biochemistry, Temple University of School of Medicine, 3307 N. Broad Street, Philadelphia, PA 19140, USA.
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Yang DQ, Halaby MJ, Li Y, Hibma JC, Burn P. Cytoplasmic ATM protein kinase: an emerging therapeutic target for diabetes, cancer and neuronal degeneration. Drug Discov Today 2011; 16:332-8. [PMID: 21315178 DOI: 10.1016/j.drudis.2011.02.001] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Revised: 12/20/2010] [Accepted: 02/02/2011] [Indexed: 10/18/2022]
Abstract
Ataxia-telangiectasia (A-T) is an autosomal recessive disorder characterized by cerebellar ataxia and oculocutaneous telangiectasias. The gene mutated in this disease, Atm (A-T mutated), encodes a serine/threonine protein kinase that has been traditionally considered to be a nuclear protein controlling cell-cycle progression. However, many of the growth abnormalities observed in patients with A-T, including neuronal degeneration and insulin resistance, remain difficult to explain with nuclear localization of ATM. Here, recent advances in elucidating the cytoplasmic localization and function of ATM are reviewed. Particular attention is given to the role of ATM in insulin signaling and Akt activation. The potential for cytoplasmic ATM protein kinase to be an emerging therapeutic target for treating diabetes, cancer and neuronal degeneration is discussed.
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Affiliation(s)
- Da-Qing Yang
- The Sanford Project, Sanford Research/USD, Sanford Health, and The Department of Pediatrics, Sanford School of Medicine of The University of South Dakota, 2301 East 60th Street North, Sioux Falls, SD 57104, USA.
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Wang D, Yuan Z, Inoue N, Cho G, Shono M, Ishikawa Y. Abnormal subcellular localization of AQP5 and downregulated AQP5 protein in parotid glands of streptozotocin-induced diabetic rats. Biochim Biophys Acta Gen Subj 2011; 1810:543-54. [PMID: 21295117 DOI: 10.1016/j.bbagen.2011.01.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 12/20/2010] [Accepted: 01/26/2011] [Indexed: 12/14/2022]
Abstract
BACKGROUND The mechanisms underlying diabetic xerostomia have not been clarified in relation with aquaporin-5 (AQP5) subcellular localization in salivary glands. METHODS Western blotting, real-time PCR, and immunocytochemistry were used to analyse AQP5 protein levels and mRNA expression. AQP5 protein levels were measured in the apical plasma membrane (APM) and detergent-insoluble fraction prepared from streptozotocin-diabetic rat parotid glands. RESULTS Despite an increase in AQP5 mRNA, AQP5 protein levels were decreased in diabetic parotid glands compared with controls. Immunohistochemical studies indicated that AQP5, under unstimulated conditions, colocalised with flotillin-2 and GM1 with a diffuse pattern in the apical cytoplasm of acinar and duct cells in both control and diabetic rats. Ten minutes after intravenous injection of muscarinic agonist cevimeline, AQP5 was dramatically increased together with flotillin-2 and GM1 in the APM of parotid acinar and duct cells of control but not diabetic rats. Sixty minutes after injection, AQP5 was located in a diffuse pattern in the apical cytoplasm in both rats. Treatment of the parotid tissues with cevimeline for 10min increased the Triton X-100 solubility of AQP5 in control but not diabetic rats. Administration of insulin to diabetic rats tended to restore the cevimeline-induced translocation of AQP5. CONCLUSION Lack of AQP5 translocation in the salivary gland in response to a muscarinic agonist and downregulation of AQP5 protein might lead to diabetic xerostomia. GENERAL SIGNIFICANCE Cevimeline is useful to cure diabetic xerostomia under insulin administration.
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Affiliation(s)
- Di Wang
- Department of Medical Pharmacology, The University of Tokushima Graduate School, Tokushima 770-8504, Japan
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Lysenko EA, Turtikova OV, Kachaeva EV, Ushakov IB, Shenkman BS. Time course of ribosomal kinase activity during hindlimb unloading. DOKL BIOCHEM BIOPHYS 2010; 434:223-6. [DOI: 10.1134/s1607672910050017] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Indexed: 11/23/2022]
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Ayuso MI, Hernández-Jiménez M, Martín ME, Salinas M, Alcázar A. New hierarchical phosphorylation pathway of the translational repressor eIF4E-binding protein 1 (4E-BP1) in ischemia-reperfusion stress. J Biol Chem 2010; 285:34355-63. [PMID: 20736160 PMCID: PMC2966049 DOI: 10.1074/jbc.m110.135103] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Eukaryotic initiation factor (eIF) 4E-binding protein 1 (4E-BP1) is a translational repressor that is characterized by its capacity to bind specifically to eIF4E and inhibit its interaction with eIF4G. Phosphorylation of 4E-BP1 regulates eIF4E availability, and therefore, cap-dependent translation, in cell stress. This study reports a physiological study of 4E-BP1 regulation by phosphorylation using control conditions and a stress-induced translational repression condition, ischemia-reperfusion (IR) stress, in brain tissue. In control conditions, 4E-BP1 was found in four phosphorylation states that were detected by two-dimensional gel electrophoresis and Western blotting, which corresponded to Thr69-phosphorylated alone, Thr69- and Thr36/Thr45-phosphorylated, all these plus Ser64 phosphorylation, and dephosphorylation of the sites analyzed. In control or IR conditions, no Thr36/Thr45 phosphorylation alone was detected without Thr69 phosphorylation, and neither was Ser64 phosphorylation without Thr36/Thr45/Thr69 phosphorylation detected. Ischemic stress induced 4E-BP1 dephosphorylation at Thr69, Thr36/Thr45, and Ser64 residues, with 4E-BP1 remaining phosphorylated at Thr69 alone or dephosphorylated. In the subsequent reperfusion, 4E-BP1 phosphorylation was induced at Thr36/Thr45 and Ser64, in addition to Thr69. Changes in 4E-BP1 phosphorylation after IR were according to those found for Akt and mammalian target of rapamycin (mTOR) kinases. These results demonstrate a new hierarchical phosphorylation for 4E-BP1 regulation in which Thr69 is phosphorylated first followed by Thr36/Thr45 phosphorylation, and Ser64 is phosphorylated last. Thr69 phosphorylation alone allows binding to eIF4E, and subsequent Thr36/Thr45 phosphorylation was sufficient to dissociate 4E-BP1 from eIF4E, which led to eIF4E-4G interaction. These data help to elucidate the physiological role of 4E-BP1 phosphorylation in controlling protein synthesis.
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Affiliation(s)
- María I Ayuso
- Department of Investigation, Hospital Ramón y Cajal, 28034 Madrid, Spain
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Viollet B, Horman S, Leclerc J, Lantier L, Foretz M, Billaud M, Giri S, Andreelli F. AMPK inhibition in health and disease. Crit Rev Biochem Mol Biol 2010; 45:276-95. [PMID: 20522000 DOI: 10.3109/10409238.2010.488215] [Citation(s) in RCA: 304] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
All living organisms depend on dynamic mechanisms that repeatedly reassess the status of amassed energy, in order to adapt energy supply to demand. The AMP-activated protein kinase (AMPK) alphabetagamma heterotrimer has emerged as an important integrator of signals managing energy balance. Control of AMPK activity involves allosteric AMP and ATP regulation, auto-inhibitory features and phosphorylation of its catalytic (alpha) and regulatory (beta and gamma) subunits. AMPK has a prominent role not only as a peripheral sensor but also in the central nervous system as a multifunctional metabolic regulator. AMPK represents an ideal second messenger for reporting cellular energy state. For this reason, activated AMPK acts as a protective response to energy stress in numerous systems. However, AMPK inhibition also actively participates in the control of whole body energy homeostasis. In this review, we discuss recent findings that support the role and function of AMPK inhibition under physiological and pathological states.
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Affiliation(s)
- Benoit Viollet
- Institut Cochin, Université Paris Descartes, CNRS UMR 8104, Paris, France.
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33
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Acute hyperglycemia rapidly stimulates VEGF mRNA translation in the kidney. Role of angiotensin type 2 receptor (AT2). Cell Signal 2010; 22:1849-57. [PMID: 20667471 DOI: 10.1016/j.cellsig.2010.07.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 07/14/2010] [Accepted: 07/19/2010] [Indexed: 11/24/2022]
Abstract
Angiotensin II (Ang II) and vascular endothelial growth factor (VEGF) are important mediators of kidney injury in diabetes. Acute hyperglycemia increased synthesis of intrarenal Ang I and Ang II and resulted in activation of both Ang II receptors, AT1 and AT2, in the kidney. Losartan (specific AT1 antagonist) or PD123319 (specific AT2 antagonist) did not affect hyperglycemia but prevented activation of renal AT1 and AT2, respectively. In murine renal cortex, acute hyperglycemia increased VEGF protein but not mRNA content after 24 h, which suggested translational regulation. Blockade of AT2, but not AT1, prevented increase in VEGF synthesis by inhibiting translation of VEGF mRNA in renal cortex. Acute hyperglycemia increased VEGF expression in wild type but not in AT2 knockout mice. Binding of heterogeneous nuclear ribonucleoprotein K to VEGF mRNA, which stimulates its translation, was prevented by blockade of AT2, but not AT1. The Akt-mTOR-p70(S6K) signaling pathway, involved in the activation of mRNA translation, was activated in hyperglycemic kidneys and was blocked by the AT2 antagonist. Elongation phase is an important step of mRNA translation that is controlled by elongation factor 1A (eEF1A) and 2 (eEF2). Expression of eEF1A and activity of eEF2 was higher in kidney cortex from hyperglycemic mice and only the AT2 antagonist prevented these changes. To assess selectivity of translational control of VEGF expression, we measured expression of fibronectin (FN) and laminin β1 (lamβ1): acute hyperglycemia increased FN expression at both protein and mRNA levels, indicating transcriptional control, and did not affect the expression of lamβ1. To confirm results obtained with PD123319, we induced hyperglycemia in AT2 knockout mice and found that in the absence of AT2, translational control of VEGF expression by hyperglycemia was abolished. Our data show that acute hyperglycemia stimulates Ang II synthesis in murine kidney cortex, this leads to AT2 activation and stimulation of VEGF mRNA translation, via the Akt-mTOR-p70(S6K) signaling pathway. Our data show that exclusive translational control of protein expression in the kidney by acute hyperglycemia is not a general phenomenon, but do not prove that it is restricted to VEGF.
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Pérez-Pérez A, Gambino Y, Maymó J, Goberna R, Fabiani F, Varone C, Sánchez-Margalet V. MAPK and PI3K activities are required for leptin stimulation of protein synthesis in human trophoblastic cells. Biochem Biophys Res Commun 2010; 396:956-60. [DOI: 10.1016/j.bbrc.2010.05.031] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2010] [Accepted: 05/06/2010] [Indexed: 11/28/2022]
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Papasani MR, Thornton K, Yinggian Z, Brezas A, Welch C, Wang G, Villasante A, Pokharel D, Cheguru P, Kotla S, Julien DC. Does obesity reduce load-induced muscle hypertrophy? J Physiol 2010; 588:1819-20. [PMID: 20516348 DOI: 10.1113/jphysiol.2010.189357] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Affiliation(s)
- Madhusudhan R Papasani
- Department of Animal and Veterinary Science, University of Idaho, Moscow, ID 83844-2330, USA.
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36
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Noori N, Kopple JD. Effect of Diabetes Mellitus on Protein-Energy Wasting and Protein Wasting in End-Stage Renal Disease. Semin Dial 2010; 23:178-84. [DOI: 10.1111/j.1525-139x.2010.00705.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Gibbons JJ, Abraham RT, Yu K. Mammalian target of rapamycin: discovery of rapamycin reveals a signaling pathway important for normal and cancer cell growth. Semin Oncol 2010; 36 Suppl 3:S3-S17. [PMID: 19963098 DOI: 10.1053/j.seminoncol.2009.10.011] [Citation(s) in RCA: 160] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Since the discovery of rapamycin, considerable progress has been made in unraveling the details of the mammalian target of rapamycin (mTOR) signaling network, including the upstream mechanisms that modulate mTOR signaling functions, and the roles of mTOR in the regulation of mRNA translation and other cell growth-related responses. mTOR is found in two different complexes within the cell, mTORC1 and mTORC2, but only mTORC1 is sensitive to inhibition by rapamycin. mTORC1 is a master controller of protein synthesis, integrating signals from growth factors within the context of the energy and nutritional conditions of the cell. Activated mTORC1 regulates protein synthesis by directly phosphorylating 4E-binding protein 1 (4E-BP1) and p70S6K (S6K), translation initiation factors that are important to cap-dependent mRNA translation, which increases the level of many proteins that are needed for cell cycle progression, proliferation, angiogenesis, and survival pathways. In normal physiology, the roles of mTOR in both glucose and lipid catabolism underscore the importance of the mTOR pathway in the production of metabolic energy in quantities sufficient to fuel cell growth and mitotic cell division. Several oncogenes and tumor-suppressor genes that activate mTORC1, often through the phosphatidylinositol 3-kinase (PI3K)/AKT pathway, are frequently dysregulated in cancer. Novel analogs of rapamycin (temsirolimus, everolimus, and deforolimus), which have improved pharmaceutical properties, were designed for oncology indications. Clinical trials of these analogs have already validated the importance of mTOR inhibition as a novel treatment strategy for several malignancies. Inhibition of mTOR now represents an attractive anti-tumor target, either alone or in combination with strategies to target other pathways that may overcome resistance. The far-reaching downstream consequences of mTOR inhibition make defining the critical molecular effector mechanisms that mediate the anti-tumor response and associated biomarkers that predict responsiveness to mTOR inhibitors a challenge and priority for the field.
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Affiliation(s)
- James J Gibbons
- Department of Oncology Discovery, Pfizer Inc., 401 N Middletown Rd., Pearl River, NY 10960, USA.
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Babu AP, Chitti S, Rajesh B, Prasanth VV, Kishen RJV, Vali KR. In silico Based Ligand Design and Docking Studies of GSK-3β Inhibitors. CHEM-BIO INFORMATICS JOURNAL 2010. [DOI: 10.1273/cbij.10.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Ajay P Babu
- Translational Research Institute of Molecular Sciences (TRIMS)
| | | | - B Rajesh
- Translational Research Institute of Molecular Sciences (TRIMS)
| | | | - Radha JV Kishen
- Translational Research Institute of Molecular Sciences (TRIMS)
| | - Khadar R Vali
- Translational Research Institute of Molecular Sciences (TRIMS)
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Pérez-Pérez A, Maymó J, Gambino Y, Dueñas JL, Goberna R, Varone C, Sánchez-Margalet V. Leptin stimulates protein synthesis-activating translation machinery in human trophoblastic cells. Biol Reprod 2009; 81:826-32. [PMID: 19553602 DOI: 10.1095/biolreprod.109.076513] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
Leptin was originally considered as an adipocyte-derived signaling molecule for the central control of metabolism. However, pleiotropic effects of leptin have been identified in reproduction and pregnancy, particularly in placenta, where it may work as an autocrine hormone, mediating angiogenesis, growth, and immunomodulation. Leptin receptor (LEPR, also known as Ob-R) shows sequence homology to members of the class I cytokine receptor (gp130) superfamily. In fact, leptin may function as a proinflammatory cytokine. We have previously found that leptin is a trophic and mitogenic factor for trophoblastic cells. In order to further investigate the mechanism by which leptin stimulates cell growth in JEG-3 cells and trophoblastic cells, we studied the phosphorylation state of different proteins of the initiation stage of translation and the total protein synthesis by [(3)H]leucine incorporation in JEG-3 cells. We have found that leptin dose-dependently stimulates the phosphorylation and activation of the translation initiation factor EIF4E as well as the phosphorylation of the EIF4E binding protein EIF4EBP1 (PHAS-I), which releases EIF4E to form active complexes. Moreover, leptin dose-dependently stimulates protein synthesis, and this effect can be partially prevented by blocking mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3 kinase (PIK3) pathways. In conclusion, leptin stimulates protein synthesis, at least in part activating the translation machinery, via the activation of MAPK and PIK3 pathways.
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Affiliation(s)
- Antonio Pérez-Pérez
- Departamento de Bioquímica Médica y Biología Molecular, Hospital Universitario Virgen Macarena, Universidad de Sevilla, Seville, Spain
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Ellederová Z, Cais O, Susor A, Uhlírová K, Kovárová H, Jelínková L, Tomek W, Kubelka M. ERK1/2 map kinase metabolic pathway is responsible for phosphorylation of translation initiation factor eIF4E during in vitro maturation of pig oocytes. Mol Reprod Dev 2008; 75:309-17. [PMID: 17290414 DOI: 10.1002/mrd.20690] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Eukaryotic initiation factor 4E (eIF4E) plays an important role in mRNA translation by binding the 5'-cap structure of the mRNA and facilitating the recruitment to the mRNA of other translation factors and the 40S ribosomal subunit. eIF4E undergoes regulated phosphorylation on Ser-209 and this phosphorylation is believed to be important for its binding to mRNA and to other initiation factors. The findings showing that the translation initiation factor eIF4E becomes gradually phosphorylated during in vitro maturation (IVM) of pig oocytes with a maximum in metaphase II (M II) stage oocytes have been documented by us recently (Ellederova et al., 2006). The aim of this work was to study in details the metabolic pathways involved in this process. Using inhibitors of cyclin-dependent kinases, Butyrolactone I (BL I) and protein phosphatases, okadaic acid (OA) we show that ERK1/2 MAP kinase pathway is involved in this phosphorylation. We also demonstrate that activation and phosphorylation of ERK1/2 MAP kinase and eIF4E is associated with the activating phosphorylation of Mnk1 kinase, one of the two main kinases phosphorylating eIF4E in somatic cells.
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Affiliation(s)
- Zdenka Ellederová
- Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Libechov, Czech Republic
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Ishizuka Y, Kakiya N, Nawa H, Takei N. Leucine induces phosphorylation and activation of p70S6K in cortical neurons via the system L amino acid transporter. J Neurochem 2008; 106:934-42. [PMID: 18435829 DOI: 10.1111/j.1471-4159.2008.05438.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
p70S6 kinase is a multipotent kinase that phosphorylates substrates in response to extracellular stimuli. This kinase activity inhibits apoptosis, regulates cell size and controls translation. In the CNS, p70S6K also participates in synaptic plasticity. In this study, we report that leucine, a branched-chain amino acid, induces phosphorylation and activation of p70S6 kinase in cortical neurons. Leucine also induces phosphorylation of S6 protein, a substrate of p70S6K. These effects of leucine are completely inhibited by rapamycin, consistent with mammalian target of rapamycin mediating p70S6 phosphorylation. Finally, we demonstrate that the action of leucine on cortical neurons is mediated by the system L amino acid transporter. Neurons express components of system L amino acid transporter LAT1, LAT2, and CD98. Leucine uptake and its effect on p70S6 kinase are both inhibited by a specific inhibitor of system L amino acid transporter. We propose that leucine plays important roles in regulating signaling by p70S6 kinase by acting as an intercellular communicator in the CNS.
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Affiliation(s)
- Yuta Ishizuka
- Department of Molecular Neurobiology, Brain Research Institute, Niigata University, Niigata, Japan
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Impaired insulin secretion and decreased expression of the nutritionally responsive ribosomal kinase protein S6K-1 in pancreatic islets from malnourished rats. Life Sci 2008; 82:542-8. [DOI: 10.1016/j.lfs.2007.12.012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2007] [Revised: 09/25/2007] [Accepted: 12/15/2007] [Indexed: 11/21/2022]
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Malcher-Lopes R, Franco A, Tasker JG. Glucocorticoids shift arachidonic acid metabolism toward endocannabinoid synthesis: a non-genomic anti-inflammatory switch. Eur J Pharmacol 2008; 583:322-39. [PMID: 18295199 DOI: 10.1016/j.ejphar.2007.12.033] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2007] [Revised: 12/12/2007] [Accepted: 12/16/2007] [Indexed: 11/24/2022]
Abstract
Glucocorticoids are capable of exerting both genomic and non-genomic actions in target cells of multiple tissues, including the brain, which trigger an array of electrophysiological, metabolic, secretory and inflammatory regulatory responses. Here, we have attempted to show how glucocorticoids may generate a rapid anti-inflammatory response by promoting arachidonic acid-containing endocannabinoids biosynthesis. According to our hypothesized model, non-genomic action of glucocorticoids results in the global shift of membrane lipid metabolism, subverting metabolic pathways toward the synthesis of the anti-inflammatory endocannabinoids, anandamide (AEA) and 2-arachidonoyl-glycerol (2-AG), and away from arachidonic acid production. Post-transcriptional inhibition of cyclooxygenase-2 (COX(2)) synthesis by glucocorticoids assists this mechanism by suppressing the synthesis of pro-inflammatory prostaglandins as well as endocannabinoid-derived prostanoids. In the central nervous system (CNS) this may represent a major neuroprotective system, which may cross-talk with leptin signaling in the hypothalamus allowing for the coordination between energy homeostasis and the inflammatory response.
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Chenal J, Pierre K, Pellerin L. Insulin and IGF-1 enhance the expression of the neuronal monocarboxylate transporter MCT2 by translational activation via stimulation of the phosphoinositide 3-kinase-Akt-mammalian target of rapamycin pathway. Eur J Neurosci 2007; 27:53-65. [PMID: 18093179 DOI: 10.1111/j.1460-9568.2007.05981.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
MCT2 is the main neuronal monocarboxylate transporter essential for facilitating lactate and ketone body utilization as energy substrates. Our study reveals that treatment of cultured cortical neurons with insulin and IGF-1 led to a striking enhancement of MCT2 immunoreactivity in a time- and concentration-dependent manner. Surprisingly, neither insulin nor IGF-1 affected MCT2 mRNA expression, suggesting that regulation of MCT2 protein expression occurs at the translational rather than the transcriptional level. Investigation of the putative signalling pathways leading to translation activation revealed that insulin and IGF-1 induced p44- and p42 MAPK, Akt and mTOR phosphorylation. S6 ribosomal protein, a component of the translational machinery, was also strongly activated by insulin and IGF-1. Phosphorylation of p44- and p42 MAPK was blocked by the MEK inhibitor PD98058, while Akt phosphorylation was abolished by the PI3K inhibitor LY294002. Phosphorylation of mTOR and S6 was blocked by the mTOR inhibitor rapamycin. In parallel, it was observed that LY294002 and rapamycin almost completely blocked the effects of insulin and IGF-1 on MCT2 protein expression, whereas PD98059 and SB202190 (a p38K inhibitor) had no effect on insulin-induced MCT2 expression and only a slight effect on IGF-1-induced MCT2 expression. At the subcellular level, a significant increase in MCT2 protein expression within an intracellular pool was observed while no change at the cell surface was apparent. As insulin and IGF-1 are involved in synaptic plasticity, their effect on MCT2 protein expression via an activation of the PI3K-Akt-mTOR-S6K pathway might contribute to the preparation of neurons for enhanced use of nonglucose energy substrates following altered synaptic efficacy.
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Affiliation(s)
- Julie Chenal
- Department of Physiology, Université de Lausanne, 7 Rue du Bugnon, 1005 Lausanne, Switzerland
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45
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Abstract
Severe burns lead to insulin resistance, which is associated with hyperglycemia and muscle wasting. Investigators showed relatively recently that control of hyperglycemia with intensive insulin treatment is associated with improved outcomes for those in the intensive care unit, including patients with severe burns. In this article, we review the actions of insulin in terms of glycemic control and muscle metabolism, biochemical and clinical effects of insulin treatment in the severely burned, and the vagaries of glucose control.
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Affiliation(s)
- Heather F Pidcoke
- Department of Surgery, University of Texas Health Science Center-San Antonio, USA
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46
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Tesseraud S, Métayer S, Duchêne S, Bigot K, Grizard J, Dupont J. Regulation of protein metabolism by insulin: value of different approaches and animal models. Domest Anim Endocrinol 2007; 33:123-42. [PMID: 16876379 DOI: 10.1016/j.domaniend.2006.06.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Revised: 06/09/2006] [Accepted: 06/09/2006] [Indexed: 01/06/2023]
Abstract
Insulin induces protein accretion by stimulating protein synthesis and inhibiting proteolysis. However, the mechanisms of regulation of protein metabolism by insulin are complex and still not completely understood. The use of approaches combining hyperinsulinemic clamp and isotopic methods, or measurement of the activation of intracellular kinases involved in insulin signaling, in addition to the use of different animal models in a comparative physiology process, provide better understanding of the potential regulation of protein metabolism by insulin. Studies using the clamp technique in lactating goats have shown a clear inhibitory effect of insulin on proteolysis, with an interaction between the effects of insulin and amino acids. Such studies revealed that the insulin-inhibited proteolysis is improved in lactating goats, this adaptative process limiting the mobilization of body protein under the conditions of amino acid deficit which occurs during early lactation. Insulin signaling studies in growing chickens have also provided some interesting features of insulin regulation compared to mammals. Refeeding or insulin injection leads to the activation of the early steps of insulin receptor signaling in the liver but not in the muscle. Muscle p70 S6 kinase, a kinase involved in the insulin activation of protein synthesis, was found to be markedly activated in response to insulin and to refeeding, suggesting that other signaling pathways than those classically described in mammalian muscles may be involved in signal transduction. Finally, although the role of insulin has been doubtful and has long been considered to be minor in ruminants and in avian species, this hormone clearly regulates protein metabolism in both species.
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47
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Sidiropoulos KG, Meshkani R, Avramoglu-Kohen R, Adeli K. Insulin inhibition of apolipoprotein B mRNA translation is mediated via the PI-3 kinase/mTOR signaling cascade but does not involve internal ribosomal entry site (IRES) initiation. Arch Biochem Biophys 2007; 465:380-8. [PMID: 17698027 DOI: 10.1016/j.abb.2007.06.029] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2007] [Revised: 06/19/2007] [Accepted: 06/30/2007] [Indexed: 01/15/2023]
Abstract
Although insulin normally activates global mRNA translation, it has a specific inhibitory effect on translation of apolipoprotein B (apoB) mRNA. This suggests that insulin induces a unique signaling cascade that leads to specific inhibition of apoB mRNA translation despite global translational stimulation. Recent studies have revealed that insulin functions to regulate apoB mRNA translation through a mechanism involving the apoB mRNA 5' untranslated region (5' UTR). Here, we further investigate the role of downstream insulin signaling molecules on apoB mRNA translation, and the mechanism of apoB mRNA translation itself. Transfection studies in HepG2 cells expressing deletion constructs of the apoB 5' UTR showed that the cis-acting region responding to insulin was localized within the first 64 nucleotides. Experiments using chimeric apoB UTR-luciferase constructs transfected into HepG2 cells followed by treatment with wortmannin, a PI-3K inhibitor, and rapamycin, an mTOR inhibitor, showed that signaling via PI-3K and mTOR pathways is necessary for insulin-mediated inhibition of chimeric 5' UTR-luciferase expression. In vitro translation of chimeric cRNA confirmed that the effects observed were translational in nature. Furthermore, using RNA-EMSA we found that wortmannin pretreatment blocked insulin-mediated inhibition of the binding of RNA-binding factor(s), migrating near the 110 kDa marker, to the 5' UTR. Radiolabeling studies in HepG2 cells also showed that insulin-mediated control of the synthesis of endogenously expressed full length apoB100 is mediated via the PI-3K and mTOR pathways. Finally, using dual-cistronic luciferase constructs we demonstrate that apoB 5' UTR may have weak internal ribosomal entry (IRES) translation which is not affected by insulin stimulation, and may function to stimulate basal levels of apoB mRNA translation.
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Affiliation(s)
- Konstantinos Gus Sidiropoulos
- Molecular Structure and Function, Research Institute, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, Canada M5G 1X8
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48
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Southgate RJ, Neill B, Prelovsek O, El-Osta A, Kamei Y, Miura S, Ezaki O, McLoughlin TJ, Zhang W, Unterman TG, Febbraio MA. FOXO1 regulates the expression of 4E-BP1 and inhibits mTOR signaling in mammalian skeletal muscle. J Biol Chem 2007; 282:21176-86. [PMID: 17510058 DOI: 10.1074/jbc.m702039200] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mammalian target of rapamycin (mTOR) is regulated by growth factors to promote protein synthesis. In mammalian skeletal muscle, the Forkhead-O1 transcription factor (FOXO1) promotes catabolism by activating ubiquitin-protein ligases. Using C2C12 mouse myoblasts that stably express inducible FOXO1-ER fusion proteins and transgenic mice that specifically overexpress constitutively active FOXO1 in skeletal muscle (FOXO(++/+)), we show that FOXO1 inhibits mTOR signaling and protein synthesis. Activation of constitutively active FOXO1 induced the expression of eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) mRNA via binding to the promoter. This resulted in an increased total 4E-BP1 abundance and a reduced 4E-BP1 (Thr-37/46) phosphorylation. The reduction in 4E-BP1 phosphorylation was associated with a reduction in the abundance of Raptor and mTOR proteins, Raptor-associated mTOR, reduced phosphorylation of the downstream protein p70S6 kinase, and attenuated incorporation of [(14)C]phenylalanine into protein. The FOXO(++/+) mice, characterized by severe skeletal muscle atrophy, displayed similar patterns of mRNA expression and protein abundance to those observed in the constitutively active FOXO1 C2C12 myotubes. These data suggest that FOXO1 may be an important therapeutic target for human diseases where anabolism is impaired.
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Affiliation(s)
- Robert J Southgate
- Cellular & Molecular Metabolism Laboratory, The Baker Heart Research Institute, Commercial Road, Melbourne 3004, Victoria, Australia
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49
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Sidiropoulos KG, Zastepa A, Adeli K. Translational control of apolipoprotein B mRNA via insulin and the protein kinase C signaling cascades: Evidence for modulation of RNA–protein interactions at the 5′UTR. Arch Biochem Biophys 2007; 459:10-9. [PMID: 17288985 DOI: 10.1016/j.abb.2006.11.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2006] [Revised: 11/02/2006] [Accepted: 11/03/2006] [Indexed: 11/30/2022]
Abstract
The link between hepatic insulin signaling and apolipoprotein B (apoB) production has important implications in understanding the etiology of metabolic dyslipidemia commonly observed in insulin-resistant states. Recent studies have revealed important translational mechanisms of apoB mRNA involving the 5' untranslated region (5'UTR) and insulin-mediated translational suppression via an insulin-sensitive RNA binding protein. Here, we have investigated the role of the protein kinase C (PKCs) signaling cascade in the regulation of apoB mRNA translation, using a series of chimeric apoB UTR-luciferase constructs, in vitro translation of UTR-luciferase cRNAs, and metabolic labeling of intact HepG2 cells. The PKC activator, phorbol 12-myristate 13-acetate (PMA), increased luciferase expression of constructs containing the apoB 5' UTR whereas treatment with Bis-I, a general PKC inhibitor or Go6976, a more specific PKC alpha/beta inhibitor, decreased expression, under both basal and insulin-treated conditions. These effects were confirmed to be translational in nature based on in vitro translation studies of T7 apoB UTR-luciferase constructs transcribed and translated in vitro in the presence of HepG2 cytosol treated with insulin or signaling modulators. Mobility shift experiments using cytosol treated with either PKC inhibitor (Bis-I) or activator (PMA) showed parallel changes between translation of apoB 5'UTR-luciferase constructs and the binding of a protein(s) complex migrating around 110 kDa to the apoB 5' UTR. ApoB mRNA levels were unaltered under these conditions based on real-time PCR analysis. Bis-I and Go6976 were both able to significantly decrease newly synthesized apoB100 protein in the presence or absence of insulin. Overall, the data suggests that PKC activation may induce increased mRNA translation and synthesis of apoB100 protein through a mechanism involving the interaction of trans-acting factors with the apoB 5'UTR. We postulate potential links between PKC activation as seen in insulin-resistant/diabetic states, enhanced translation of apoB mRNA, and hepatic VLDL-apoB overproduction.
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Affiliation(s)
- Konstantinos Gus Sidiropoulos
- Clinical Biochemistry Division, Department of Laboratory Medicine and Pathobiology, Hospital for Sick Children, University of Toronto, Toronto, Ont., Canada M5G 1X8
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50
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Abstract
Skeletal muscle size is dynamic and responsive to extracellular signals such as mechanical load, neural activity, hormones, growth factors, and cytokines. The signaling pathways responsible for regulating cell size in adult skeletal muscle under growth and atrophy conditions are poorly understood. However, recent evidence suggests a role for the PI3K/Akt/mTOR pathway. Protein translation is regulated through the phosphorylation of initiation factors that are controlled by signaling pathways downstream of PI3K/Akt. Recent work in mammals has suggested that activation of Akt/PKB, a Ser-Thr phosphatidylinositol-regulated kinase, and its downstream targets, glycogen synthase kinase-3 (GSK3) and the mammalian target of rapamycin (mTOR), may be critical regulators of postnatal cell size in multiple organ systems, including skeletal muscle. This paper will review some of the recent data that demonstrate the critical role of Akt/mTOR signaling in the regulation of postnatal muscle size, especially under conditions of increased external loading.
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Affiliation(s)
- Sue C Bodine
- Section of Neurobiology, Physiology & Behavior, University of California Davis, Davis, CA 95616, USA.
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