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Flaherty SE, Bezy O, Zheng W, Yan D, Li X, Jagarlapudi S, Albuquerque B, Esquejo RM, Peloquin M, Semache M, Mancini A, Kang L, Drujan D, Breitkopf SB, Griffin JD, Jean Beltran PM, Xue L, Stansfield J, Pashos E, Shakey Q, Pehmøller C, Monetti M, Birnbaum MJ, Fortin JP, Wu Z. Chronic UCN2 treatment desensitizes CRHR2 and improves insulin sensitivity. Nat Commun 2023; 14:3953. [PMID: 37402735 DOI: 10.1038/s41467-023-39597-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 06/21/2023] [Indexed: 07/06/2023] Open
Abstract
Urocortin 2 (UCN2) acts as a ligand for the G protein-coupled receptor corticotropin-releasing hormone receptor 2 (CRHR2). UCN2 has been reported to improve or worsen insulin sensitivity and glucose tolerance in vivo. Here we show that acute dosing of UCN2 induces systemic insulin resistance in male mice and skeletal muscle. Inversely, chronic elevation of UCN2 by injection with adenovirus encoding UCN2 resolves metabolic complications, improving glucose tolerance. CRHR2 recruits Gs in response to low concentrations of UCN2, as well as Gi and β-Arrestin at high concentrations of UCN2. Pre-treating cells and skeletal muscle ex vivo with UCN2 leads to internalization of CRHR2, dampened ligand-dependent increases in cAMP, and blunted reductions in insulin signaling. These results provide mechanistic insights into how UCN2 regulates insulin sensitivity and glucose metabolism in skeletal muscle and in vivo. Importantly, a working model was derived from these results that unifies the contradictory metabolic effects of UCN2.
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Affiliation(s)
- Stephen E Flaherty
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Olivier Bezy
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Wei Zheng
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Dong Yan
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Xiangping Li
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Srinath Jagarlapudi
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Bina Albuquerque
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Ryan M Esquejo
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Matthew Peloquin
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | | | | | - Liya Kang
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Doreen Drujan
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Susanne B Breitkopf
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - John D Griffin
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Pierre M Jean Beltran
- Machine Learning and Computational Sciences, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Liang Xue
- Machine Learning and Computational Sciences, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - John Stansfield
- Biostatistics, Early Clinical Development, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Evanthia Pashos
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Quazi Shakey
- Biomedicine design, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Christian Pehmøller
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Mara Monetti
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Morris J Birnbaum
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Jean-Philippe Fortin
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA
| | - Zhidan Wu
- Internal Medicine Research Unit, Pfizer Inc., 1 Portland Street, Cambridge, MA, USA.
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2
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Bhargava A. Unraveling corticotropin-releasing factor family-orchestrated signaling and function in both sexes. VITAMINS AND HORMONES 2023; 123:27-65. [PMID: 37717988 DOI: 10.1016/bs.vh.2023.01.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/16/2023]
Abstract
Stress responses to physical, psychological, environmental, or cellular stressors, has two arms: initiation and recovery. Corticotropin-releasing factor (CRF) is primarily responsible for regulating and/or initiating stress responses via, whereas urocortins (UCNs) are involved in the recovery response to stress via feedback inhibition. Stress is a loaded, polysemous word and is experienced in a myriad of ways. Some stressors are good for an individual, in fact essential, whereas other stressors are associated with bad outcomes. Perceived stress, like beauty, lies in the eye of the beholder, and hence the same stressor can result in individual-specific outcomes. In mammals, there are two main biological sexes with reproduction as primary function. Reproduction and nutrition can also be viewed as stressors; based on a body of work from my laboratory, we propose that the functions of all other organs have co-evolved to optimize and facilitate an individual's nutritional and reproductive functions. Hence, sex differences in physiologically relevant outcomes are innate and occur at all levels- molecular, endocrine, immune, and (patho)physiological. CRF and three UCNs are peptide hormones that mediate their physiological effects by binding to two known G protein-coupled receptors (GPCRs), CRF1 and CRF2. Expression and function of CRF family of hormones and their receptors is likely to be sexually dimorphic in all organs. In this chapter, based on the large body of work from others and my laboratory, an overview of the CRF family with special emphasis on sex-specific actions of peripherally expressed CRF2 receptor in health and disease is provided.
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Affiliation(s)
- Aditi Bhargava
- Center for Reproductive Sciences, Department of Obstetrics and Gynecology, University of California San Francisco, San Francisco, CA, United States.
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3
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Kavalakatt S, Khadir A, Madhu D, Devarajan S, Warsame S, AlKandari H, AlMahdi M, Koistinen HA, Al‐Mulla F, Tuomilehto J, Abubaker J, Tiss A. Circulating levels of urocortin neuropeptides are impaired in children with overweight. Obesity (Silver Spring) 2022; 30:472-481. [PMID: 35088550 PMCID: PMC9305428 DOI: 10.1002/oby.23356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 11/09/2021] [Accepted: 11/12/2021] [Indexed: 11/09/2022]
Abstract
OBJECTIVE The corticotropin-releasing factor neuropeptides (corticotropin-releasing hormone [CRH] and urocortin [UCN]-1,2,3) and spexin contribute to the regulation of energy balance and inhibit food intake in mammals. However, the status of these neuropeptides in children with overweight has yet to be elucidated. This study investigated the effect of increased body weight on the circulating levels of these neuropeptides. METHODS A total of 120 children with a mean age of 12 years were enrolled in the study. Blood samples were collected to assess the circulating levels of neuropeptides and were correlated with various anthropometric, clinical, and metabolic markers. RESULTS Plasma levels of UCNs were altered in children with overweight but less so in those with obesity. Furthermore, the expression pattern of UCN1 was opposite to that of UCN2 and UCN3, which suggests a compensatory effect. However, no significant effect of overweight and obesity was observed on CRH and spexin levels. Finally, UCN3 independently associated with circulating zinc-alpha-2-glycoprotein and UCN2 levels, whereas UCN1 was strongly predicted by TNFα levels. CONCLUSIONS Significant changes in neuropeptide levels were primarily observed in children with overweight and were attenuated with increased obesity. This suggests the presence of a compensatory mechanism for neuropeptides to curb the progression of obesity.
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Affiliation(s)
- Sina Kavalakatt
- Biochemistry and Molecular Biology Department, Research DivisionDasman Diabetes InstituteKuwait
- Faculty of MedicineUniversity of HelsinkiHelsinkiFinland
| | - Abdelkrim Khadir
- Biochemistry and Molecular Biology Department, Research DivisionDasman Diabetes InstituteKuwait
| | - Dhanya Madhu
- Biochemistry and Molecular Biology Department, Research DivisionDasman Diabetes InstituteKuwait
| | | | - Samia Warsame
- Biochemistry and Molecular Biology Department, Research DivisionDasman Diabetes InstituteKuwait
| | | | | | - Heikki A. Koistinen
- Department of MedicineHelsinki University HospitalHelsinkiFinland
- Minerva Foundation Institute for Medical ResearchHelsinkiFinland
- Department of Public Health and WelfareFinnish Institute for Health and WelfareHelsinkiFinland
| | | | - Jaakko Tuomilehto
- Department of Public Health and WelfareFinnish Institute for Health and WelfareHelsinkiFinland
- Department of Public HealthUniversity of HelsinkiHelsinkiFinland
- Diabetes Research GroupKing Abdulaziz UniversityJeddahSaudi Arabia
| | - Jehad Abubaker
- Biochemistry and Molecular Biology Department, Research DivisionDasman Diabetes InstituteKuwait
| | - Ali Tiss
- Biochemistry and Molecular Biology Department, Research DivisionDasman Diabetes InstituteKuwait
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Urocortin Neuropeptide Levels Are Impaired in the PBMCs of Overweight Children. Nutrients 2022; 14:nu14030429. [PMID: 35276788 PMCID: PMC8839374 DOI: 10.3390/nu14030429] [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: 12/16/2021] [Revised: 01/13/2022] [Accepted: 01/14/2022] [Indexed: 11/18/2022] Open
Abstract
The corticotropin-releasing hormone (CRH) and urocortins (UCNs) have been implicated in energy homeostasis and the cellular stress response. However, the expression of these neuropeptides in children remains unclear. Therefore, we determined the impact of obesity on their expression in 40 children who were normal weight, overweight, and had obesity. Peripheral blood mononuclear cells (PBMCs) and plasma were used to assess the expression of neuropeptides. THP1 cells were treated with 25 mM glucose and 200 µM palmitate, and gene expression was measured by real-time polymerase chain reaction (RT-PCR). Transcript levels of neuropeptides were decreased in PBMCs from children with increased body mass index as indicated by a significant decrease in UCN1, UCN3, and CRH mRNA in overweight and obese children. UCN3 mRNA expression was strongly correlated with UCN1, UCN2, and CRH. Exposure of THP1 cells to palmitate or a combination of high glucose and palmitate for 24 h increased CRH, UCN2, and UCN3 mRNA expression with concomitant increased levels of inflammatory and endoplasmic reticulum stress markers, suggesting a crosstalk between these neuropeptides and the cellular stress response. The differential impairment of the transcript levels of CRH and UCNs in PBMCs from overweight and obese children highlights their involvement in obesity-related metabolic and cellular stress.
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Borg ML, Massart J, De Castro Barbosa T, Archilla-Ortega A, Smith JAB, Lanner JT, Alsina-Fernandez J, Yaden B, Culver AE, Karlsson HKR, Brozinick JT, Zierath JR. Modified UCN2 peptide treatment improves skeletal muscle mass and function in mouse models of obesity-induced insulin resistance. J Cachexia Sarcopenia Muscle 2021; 12:1232-1248. [PMID: 34342159 PMCID: PMC8517345 DOI: 10.1002/jcsm.12746] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/25/2021] [Accepted: 06/08/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Type 2 diabetes and obesity are often seen concurrently with skeletal muscle wasting, leading to further derangements in function and metabolism. Muscle wasting remains an unmet need for metabolic disease, and new approaches are warranted. The neuropeptide urocortin 2 (UCN2) and its receptor corticotropin releasing factor receptor 2 (CRHR2) are highly expressed in skeletal muscle and play a role in regulating energy balance, glucose metabolism, and muscle mass. The aim of this study was to investigate the effects of modified UCN2 peptides as a pharmaceutical therapy to counteract the loss of skeletal muscle mass associated with obesity and casting immobilization. METHODS High-fat-fed mice (C57Bl/6J; 26 weeks old) and ob/ob mice (11 weeks old) were injected daily with a PEGylated (Compound A) and non-PEGylated (Compound B) modified human UCN2 at 0.3 mg/kg subcutaneously for 14 days. A separate group of chow-fed C57Bl/6J mice (12 weeks old) was subjected to hindlimb cast immobilization and, after 1 week, received daily injections with Compound A. In vivo functional tests were performed to measure protein synthesis rates and skeletal muscle function. Ex vivo functional and molecular tests were performed to measure contractile force and signal transduction of catabolic and anabolic pathways in skeletal muscle. RESULTS Skeletal muscles (extensor digitorum longus, soleus, and tibialis anterior) from high-fat-fed mice treated with Compound A were ~14% heavier than muscles from vehicle-treated mice. Chronic treatment with modified UCN2 peptides altered the expression of structural genes and transcription factors in skeletal muscle in high-fat diet-induced obesity including down-regulation of Trim63 and up-regulation of Nr4a2 and Igf1 (P < 0.05 vs. vehicle). Signal transduction via both catabolic and anabolic pathways was increased in tibialis anterior muscle, with increased phosphorylation of ribosomal protein S6 at Ser235/236 , FOXO1 at Ser256 , and ULK1 at Ser317 , suggesting that UCN2 treatment modulates protein synthesis and degradation pathways (P < 0.05 vs. vehicle). Acutely, a single injection of Compound A in drug-naïve mice had no effect on the rate of protein synthesis in skeletal muscle, as measured via the surface sensing of translation method, while the expression of Nr4a3 and Ppargc1a4 was increased (P < 0.05 vs. vehicle). Compound A treatment prevented the loss of force production from disuse due to casting. Compound B treatment increased time to fatigue during ex vivo contractions of fast-twitch extensor digitorum longus muscle. Compound A and B treatment increased lean mass and rates of skeletal muscle protein synthesis in ob/ob mice. CONCLUSIONS Modified human UCN2 is a pharmacological candidate for the prevention of the loss of skeletal muscle mass associated with obesity and immobilization.
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Affiliation(s)
- Melissa L Borg
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Julie Massart
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Thais De Castro Barbosa
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Adrià Archilla-Ortega
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Jonathon A B Smith
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Johanna T Lanner
- Department of Physiology and Pharmacology, Section for Molecular Muscle Physiology and Pathophysiology, Karolinska Institutet, Stockholm, Sweden
| | | | - Benjamin Yaden
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN, USA
| | - Alexander E Culver
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN, USA
| | - Håkan K R Karlsson
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Joseph T Brozinick
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN, USA
| | - Juleen R Zierath
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden.,Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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6
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Kavalakatt S, Khadir A, Madhu D, Koistinen HA, Al-Mulla F, Tuomilehto J, Abubaker J, Tiss A. Urocortin 3 overexpression reduces ER stress and heat shock response in 3T3-L1 adipocytes. Sci Rep 2021; 11:15666. [PMID: 34341463 PMCID: PMC8329193 DOI: 10.1038/s41598-021-95175-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Accepted: 07/19/2021] [Indexed: 11/09/2022] Open
Abstract
The neuropeptide urocortin 3 (UCN3) has a beneficial effect on metabolic disorders, such as obesity, diabetes, and cardiovascular disease. It has been reported that UCN3 regulates insulin secretion and is dysregulated with increasing severity of obesity and diabetes. However, its function in the adipose tissue is unclear. We investigated the overexpression of UCN3 in 3T3-L1 preadipocytes and differentiated adipocytes and its effects on heat shock response, ER stress, inflammatory markers, and glucose uptake in the presence of stress-inducing concentrations of palmitic acid (PA). UCN3 overexpression significantly downregulated heat shock proteins (HSP60, HSP72 and HSP90) and ER stress response markers (GRP78, PERK, ATF6, and IRE1α) and attenuated inflammation (TNFα) and apoptosis (CHOP). Moreover, enhanced glucose uptake was observed in both preadipocytes and mature adipocytes, which is associated with upregulated phosphorylation of AKT and ERK but reduced p-JNK. Moderate effects of UCN3 overexpression were also observed in the presence of 400 μM of PA, and macrophage conditioned medium dramatically decreased the UCN3 mRNA levels in differentiated 3T3-L1 cells. In conclusion, the beneficial effects of UCN3 in adipocytes are reflected, at least partially, by the improvement in cellular stress response and glucose uptake and attenuation of inflammation and apoptosis.
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Affiliation(s)
- Sina Kavalakatt
- Biochemistry and Molecular Biology Department, Research Division, Dasman Diabetes Institute, P.O. Box 1180, 15462, Dasman, Kuwait
| | - Abdelkrim Khadir
- Biochemistry and Molecular Biology Department, Research Division, Dasman Diabetes Institute, P.O. Box 1180, 15462, Dasman, Kuwait
| | - Dhanya Madhu
- Biochemistry and Molecular Biology Department, Research Division, Dasman Diabetes Institute, P.O. Box 1180, 15462, Dasman, Kuwait
| | - Heikki A Koistinen
- University of Helsinki and Department of Medicine, Helsinki University Central Hospital, Helsinki, Finland.,Minerva Foundation Institute for Medical Research, Helsinki, Finland.,Department of Public Health Solutions, Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Fahd Al-Mulla
- Research Division, Dasman Diabetes Institute, Dasman, Kuwait
| | - Jaakko Tuomilehto
- Department of Public Health Solutions, Finnish Institute for Health and Welfare, Helsinki, Finland.,Department of Public Health, University of Helsinki, Helsinki, Finland
| | - Jehad Abubaker
- Biochemistry and Molecular Biology Department, Research Division, Dasman Diabetes Institute, P.O. Box 1180, 15462, Dasman, Kuwait
| | - Ali Tiss
- Biochemistry and Molecular Biology Department, Research Division, Dasman Diabetes Institute, P.O. Box 1180, 15462, Dasman, Kuwait.
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7
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Benchoula K, Arya A, Parhar IS, Hwa WE. FoxO1 signaling as a therapeutic target for type 2 diabetes and obesity. Eur J Pharmacol 2020; 891:173758. [PMID: 33249079 DOI: 10.1016/j.ejphar.2020.173758] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 10/12/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023]
Abstract
Glucose production and the consumption of high levels of carbohydrate increase the chance of insulin resistance, especially in cases of obesity. Therefore, maintaining a balanced glucose homeostasis might form a strategy to prevent or cure diabetes and obesity. The activation and inhibition of glucose production is complicated due to the presence of many interfering pathways. These pathways can be viewed at the downstream level because they activate certain transcription factors, which include the Forkhead-O1 (FoxO1). This has been identified as a significant agent in the pancreas, liver, and adipose tissue, which is significant in the regulation of lipids and glucose. The objective of this review is to discuss the intersecting portrayal of FoxO1 and its parallel cross-talk which highlights obesity-induced insulin susceptibility in the discovery of a targeted remedy. The review also analyses current progress and provides a blueprint on therapeutics, small molecules, and extracts/phytochemicals which are explored at the pre-clinical level.
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Affiliation(s)
- Khaled Benchoula
- School of Medicine, Faculty of Health and Medical Sciences, Taylor's University, Subang Jaya, Malaysia
| | - Aditya Arya
- Department of Pharmacology and Therapeutics, School of Medicine, Faculty of Health and Medical Sciences, Taylor's University, Subang Jaya, Malaysia; Department of Pharmacology and Therapeutics, Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, Victoria, 3010, Australia; Malaysian Institute of Pharmaceuticals and Nutraceuticals (IPharm), Bukit Gambir, Gelugor, Pulau Pinang, Malaysia
| | - Ishwar S Parhar
- Monash University (Malaysia) BRIMS, Jeffrey Cheah School of Medicine & Health Sciences, Malaysia
| | - Wong Eng Hwa
- School of Medicine, Faculty of Health and Medical Sciences, Taylor's University, Subang Jaya, Malaysia.
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8
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Alarslan P, Unal Kocabas G, Demir I, Guler A, Bozkaya G, Aslanipour B, Calan M. Increased urocortin 3 levels are associated with the risk of having type 2 diabetes mellitus. J Diabetes 2020; 12:474-482. [PMID: 31893569 DOI: 10.1111/1753-0407.13020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 12/07/2019] [Accepted: 12/29/2019] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Urocortin 3 (UCN3) is a peptide hormone playing a pivotal role in glucose and lipid metabolisms. However, its clinical implications remain unclear. Our aims were to investigate the altered levels of UCN3 in newly diagnosed type 2 diabetes mellitus (nT2DM) patients in comparison to subjects with normal glucose tolerance (NGT) and to determine the presence of any possible link between UCN3 levels and metabolic parameters. METHODS Eighty nT2DM and 80 age-, body mass index (BMI)-, and gender-matched NGT subjects were enrolled into this case-control study. The circulating UCN3 levels were measured using the enzyme-linked immunoabsorbent assay (ELISA). Metabolic parameters of enrolled subjects were also determined. A standard 75-g 2-hour oral glucose tolerance test was used for diagnosis of type 2 diabetes mellitus (T2DM). RESULTS UCN3 levels were higher in subjects with nT2DM than in controls (115.64 ± 39.26 vs 86.16 ± 22.81 pg/mL, P < .001). UCN3 levels were increased in subjects with metabolic syndrome compared to subjects without metabolic syndrome in both nT2DM and NGT groups. UCN3 levels showed a positive correlation with BMI in both groups. Moreover, UCN3 levels were positively and independently associated with insulin, fasting blood glucose, insulin resistance, 2-hour plasma glucose, glycosylated hemoglobin, and triglycerides, whereas UCN3 levels were negatively and independently associated with high-density lipoprotein cholesterol. According to logistic regression analysis, increased risk of T2DM and metabolic syndrome were parallel with the highest elevated levels of UCN3. CONCLUSIONS Increased levels of UCN3 are associated with unfavorable metabolic profiles in T2DM, indicating a potential role of UCN3 in glucose and lipid metabolisms in T2DM.
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Affiliation(s)
- Pınar Alarslan
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey
| | - Gokcen Unal Kocabas
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey
| | - Ismail Demir
- Department of Internal Medicine, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey
| | - Aslı Guler
- Department of Family Physician, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey
| | - Giray Bozkaya
- Department of Clinical Biochemistry, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey
| | - Behnaz Aslanipour
- Department of Biotechnology, Graduate School of Natural and Applied Sciences, Ege University, Izmir, Turkey
| | - Mehmet Calan
- Division of Endocrinology and Metabolism, Department of Internal Medicine, Izmir Bozyaka Training and Research Hospital, Izmir, Turkey
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9
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Farrash W, Brook M, Crossland H, Phillips BE, Cegielski J, Wilkinson DJ, Constantin-Teodosiu D, Greenhaff PL, Smith K, Cleasby M, Atherton PJ. Impacts of rat hindlimb Fndc5/irisin overexpression on muscle and adipose tissue metabolism. Am J Physiol Endocrinol Metab 2020; 318:E943-E955. [PMID: 32369414 PMCID: PMC7311674 DOI: 10.1152/ajpendo.00034.2020] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Myokines, such as irisin, have been purported to exert physiological effects on skeletal muscle in an autocrine/paracrine fashion. In this study, we aimed to investigate the mechanistic role of in vivo fibronectin type III domain-containing 5 (Fndc5)/irisin upregulation in muscle. Overexpression (OE) of Fndc5 in rat hindlimb muscle was achieved by in vivo electrotransfer, i.e., bilateral injections of Fndc5 harboring vectors for OE rats (n = 8) and empty vector for control rats (n = 8). Seven days later, a bolus of D2O (7.2 mL/kg) was administered via oral gavage to quantify muscle protein synthesis. After an overnight fast, on day 9, 2-deoxy-d-glucose-6-phosphate (2-DG6P; 6 mg/kg) was provided during an intraperitoneal glucose tolerance test (2 g/kg) to assess glucose handling. Animals were euthanized, musculus tibialis cranialis muscles and subcutaneous fat (inguinal) were harvested, and metabolic and molecular effects were evaluated. Muscle Fndc5 mRNA increased with OE (~2-fold; P = 0.014), leading to increased circulating irisin (1.5 ± 0.9 to 3.5 ± 1.2 ng/mL; P = 0.049). OE had no effect on protein anabolism or mitochondrial biogenesis; however, muscle glycogen was increased, along with glycogen synthase 1 gene expression (P = 0.04 and 0.02, respectively). In addition to an increase in glycogen synthase activation in OE (P = 0.03), there was a tendency toward increased glucose transporter 4 protein (P = 0.09). However, glucose uptake (accumulation of 2-DG6P) was identical. Irisin elicited no endocrine effect on mitochondrial biogenesis or uncoupling proteins in white adipose tissue. Hindlimb overexpression led to physiological increases in Fndc5/irisin. However, our data indicate limited short-term impacts of irisin in relation to muscle anabolism, mitochondrial biogenesis, glucose uptake, or adipose remodeling.
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Affiliation(s)
- W Farrash
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
- College of Applied Medical Sciences, Umm Al-Qura University, Makkah, Saudi Arabia
| | - M Brook
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - H Crossland
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - B E Phillips
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - J Cegielski
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - D J Wilkinson
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - D Constantin-Teodosiu
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - P L Greenhaff
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research, School of Life Sciences, University of Nottingham, Nottingham, United Kingdom
| | - K Smith
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
| | - M Cleasby
- Molecular Physiology of Diabetes Laboratory, Department of Comparative Biomedical Sciences, Royal Veterinary College, University of London, London, United Kingdom
| | - P J Atherton
- Medical Research Council Versus Arthritis Centre for Musculoskeletal Ageing Research and Nottingham National Institute for Health Research Biomedical Research Centre, School of Medicine, University of Nottingham, Derby, United Kingdom
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10
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Borg ML, Massart J, Schönke M, De Castro Barbosa T, Guo L, Wade M, Alsina-Fernandez J, Miles R, Ryan A, Bauer S, Coskun T, O'Farrell E, Niemeier EM, Chibalin AV, Krook A, Karlsson HK, Brozinick JT, Zierath JR. Modified UCN2 Peptide Acts as an Insulin Sensitizer in Skeletal Muscle of Obese Mice. Diabetes 2019; 68:1403-1414. [PMID: 31010957 DOI: 10.2337/db18-1237] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2018] [Accepted: 04/08/2019] [Indexed: 11/13/2022]
Abstract
The neuropeptide urocortin 2 (UCN2) and its receptor corticotropin-releasing hormone receptor 2 (CRHR2) are highly expressed in skeletal muscle and play a role in regulating energy balance and glucose metabolism. We investigated a modified UCN2 peptide as a potential therapeutic agent for the treatment of obesity and insulin resistance, with a specific focus on skeletal muscle. High-fat-fed mice (C57BL/6J) were injected daily with a PEGylated UCN2 peptide (compound A) at 0.3 mg/kg subcutaneously for 14 days. Compound A reduced body weight, food intake, whole-body fat mass, and intramuscular triglycerides compared with vehicle-treated controls. Furthermore, whole-body glucose tolerance was improved by compound A treatment, with increased insulin-stimulated Akt phosphorylation at Ser473 and Thr308 in skeletal muscle, concomitant with increased glucose transport into extensor digitorum longus and gastrocnemius muscle. Mechanistically, this is linked to a direct effect on skeletal muscle because ex vivo exposure of soleus muscle from chow-fed lean mice to compound A increased glucose transport and insulin signaling. Moreover, exposure of GLUT4-Myc-labeled L6 myoblasts to compound A increased GLUT4 trafficking. Our results demonstrate that modified UCN2 peptides may be efficacious in the treatment of type 2 diabetes by acting as an insulin sensitizer in skeletal muscle.
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Affiliation(s)
- Melissa L Borg
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Julie Massart
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Milena Schönke
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Thais De Castro Barbosa
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Lili Guo
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN
| | - Mark Wade
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN
| | | | - Rebecca Miles
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN
| | - Andrew Ryan
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN
| | - Steve Bauer
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN
| | - Tamer Coskun
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN
| | - Elizabeth O'Farrell
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN
| | - Evan M Niemeier
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN
| | - Alexander V Chibalin
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Anna Krook
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Håkan K Karlsson
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
| | - Joseph T Brozinick
- Lilly Research Laboratories, Division of Eli Lilly and Company, Indianapolis, IN
| | - Juleen R Zierath
- Department of Physiology and Pharmacology, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
- Department of Molecular Medicine and Surgery, Section for Integrative Physiology, Karolinska Institutet, Stockholm, Sweden
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11
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Rubio-Ruiz ME, Guarner-Lans V, Pérez-Torres I, Soto ME. Mechanisms Underlying Metabolic Syndrome-Related Sarcopenia and Possible Therapeutic Measures. Int J Mol Sci 2019; 20:ijms20030647. [PMID: 30717377 PMCID: PMC6387003 DOI: 10.3390/ijms20030647] [Citation(s) in RCA: 88] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2019] [Revised: 01/30/2019] [Accepted: 01/30/2019] [Indexed: 12/15/2022] Open
Abstract
Although there are several reviews that report the interrelationship between sarcopenia and obesity and insulin resistance, the relation between sarcopenia and the other signs that compose the metabolic syndrome (MetS) has not been extensively revised. Here, we review the mechanisms underlying MetS-related sarcopenia and discuss the possible therapeutic measures proposed. A vicious cycle between the loss of muscle and the accumulation of intramuscular fat might be associated with MetS via a complex interplay of factors including nutritional intake, physical activity, body fat, oxidative stress, proinflammatory cytokines, insulin resistance, hormonal changes, and mitochondrial dysfunction. The enormous differences in lipid storage capacities between the two genders and elevated amounts of endogenous fat having lipotoxic effects that lead to the loss of muscle mass are discussed. The important repercussions of MetS-related sarcopenia on other illnesses that lead to increased disability, morbidity, and mortality are also addressed. Additional research is needed to better understand the pathophysiology of MetS-related sarcopenia and its consequences. Although there is currently no consensus on the treatment, lifestyle changes including diet and power exercise seem to be the best options.
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Affiliation(s)
- María Esther Rubio-Ruiz
- Department of Physiology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, Mexico City 14080, Mexico.
| | - Verónica Guarner-Lans
- Department of Physiology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, Mexico City 14080, Mexico.
| | - Israel Pérez-Torres
- Department of Pathology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, Mexico City 14080, Mexico.
| | - María Elena Soto
- Department of Immunology, Instituto Nacional de Cardiología "Ignacio Chávez", Juan Badiano 1, Sección XVI, Tlalpan, Mexico City 14080, Mexico.
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12
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Kavalakatt S, Khadir A, Madhu D, Hammad M, Devarajan S, Abubaker J, Al-Mulla F, Tuomilehto J, Tiss A. Urocortin 3 Levels Are Impaired in Overweight Humans With and Without Type 2 Diabetes and Modulated by Exercise. Front Endocrinol (Lausanne) 2019; 10:762. [PMID: 31781037 PMCID: PMC6851015 DOI: 10.3389/fendo.2019.00762] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Accepted: 10/21/2019] [Indexed: 12/26/2022] Open
Abstract
Urocortin3 (UCN3) regulates metabolic functions and is involved in cellular stress response. Although UCN3 is expressed in human adipose tissue, the association of UCN3 with obesity and diabetes remains unclear. This study investigated the effects of Type 2 diabetes (T2D) and increased body weight on the circulatory and subcutaneous adipose tissue (SAT) levels of UCN3 and assessed UCN3 modulation by a regular physical exercise. Normal-weight (n = 37) and overweight adults with and without T2D (n = 98 and n = 107, respectively) were enrolled in the study. A subset of the overweight subjects (n = 39 for each group) underwent a supervised 3-month exercise program combining both moderate intensity aerobic exercise and resistance training with treadmill. UCN3 levels in SAT were measured by immunofluorescence and RT-PCR. Circulatory UCN3 in plasma was assessed by ELISA and was correlated with various clinical and metabolic markers. Our data revealed that plasma UCN3 levels decreased in overweight subjects without T2D compared with normal-weight controls [median; 11.99 (0.78-86.07) and 6.27 (0.64-77.04), respectively; p < 0.001], whereas plasma UCN3 levels increased with concomitant T2D [median; 9.03 (0.77-104.92) p < 0.001]. UCN3 plasma levels were independently associated with glycemic index; fasting plasma glucose and hemoglobin A1c (r = 0.16 and r = 0.20, p < 0.05, respectively) and were significantly different between both overweight, with and without T2D, and normal-weight individuals (OR = 2.11 [1.84-4.11, 95% CI] and OR = 2.12 [1.59-3.10, 95% CI], p < 0.01, respectively). Conversely, the UCN3 patterns observed in SAT were opposite to those in circulation; UCN3 levels were significantly increased with body weight and decreased with T2D. After a 3-month supervised exercise protocol, UCN3 expression showed a significant reduction in SAT of both overweight groups (2.3 and 1.6-fold change; p < 0.01, respectively). In conclusion, UCN levels are differentially dysregulated in obesity in a tissue-dependent manner and can be mitigated by regular moderate physical exercise.
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Affiliation(s)
- Sina Kavalakatt
- Research Division, Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Abdelkrim Khadir
- Research Division, Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Dhanya Madhu
- Research Division, Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Maha Hammad
- Research Division, Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Kuwait City, Kuwait
| | | | - Jehad Abubaker
- Research Division, Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Fahd Al-Mulla
- Research Division, Dasman Diabetes Institute, Kuwait City, Kuwait
| | - Jaakko Tuomilehto
- Research Division, Dasman Diabetes Institute, Kuwait City, Kuwait
- Department of Public Health, University of Helsinki, Helsinki, Finland
- Department of Public Health Solutions, National Institute for Health and Welfare, Helsinki, Finland
| | - Ali Tiss
- Research Division, Biochemistry and Molecular Biology Department, Dasman Diabetes Institute, Kuwait City, Kuwait
- *Correspondence: Ali Tiss
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13
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Xu Y, Zhou H, Zhu Q. The Impact of Microbiota-Gut-Brain Axis on Diabetic Cognition Impairment. Front Aging Neurosci 2017; 9:106. [PMID: 28496408 PMCID: PMC5406474 DOI: 10.3389/fnagi.2017.00106] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 03/31/2017] [Indexed: 12/11/2022] Open
Abstract
Progressive cognitive dysfunction is a central characteristic of diabetic encephalopathy (DE). With an aging population, the incidence of DE is rising and it has become a major threat that seriously affects public health. Studies within this decade have indicated the important role of risk factors such as oxidative stress and inflammation on the development of cognitive impairment. With the recognition of the two-way communication between gut and brain, recent investigation suggests that “microbiota-gut-brain axis” also plays a pivotal role in modulating both cognition function and endocrine stability. This review aims to systemically elucidate the underlying impact of diabetes on cognitive impairment.
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Affiliation(s)
- Youhua Xu
- Faculty of Chinese Medicine, Macau University of Science and TechnologyTaipa, Macau.,State Key Laboratory of Quality Research in Chinese Medicine (Macau University of Science and Technology)Taipa, Macau
| | - Hua Zhou
- Faculty of Chinese Medicine, Macau University of Science and TechnologyTaipa, Macau.,State Key Laboratory of Quality Research in Chinese Medicine (Macau University of Science and Technology)Taipa, Macau.,Laboratory for Bioassay and Molecular Pharmacology of Chinese Medicines, Macau Institute for Applied Research in Medicine and HealthTaipa, Macau
| | - Quan Zhu
- Faculty of Chinese Medicine, Macau University of Science and TechnologyTaipa, Macau.,State Key Laboratory of Quality Research in Chinese Medicine (Macau University of Science and Technology)Taipa, Macau.,Laboratory for Bioassay and Molecular Pharmacology of Chinese Medicines, Macau Institute for Applied Research in Medicine and HealthTaipa, Macau.,Guangdong Consun Pharmaceutical Group, Institute of Consun Co. for Chinese Medicine in Kidney DiseasesGuangzhou, China
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14
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Sylow L, Kleinert M, Richter EA, Jensen TE. Exercise-stimulated glucose uptake - regulation and implications for glycaemic control. Nat Rev Endocrinol 2017; 13:133-148. [PMID: 27739515 DOI: 10.1038/nrendo.2016.162] [Citation(s) in RCA: 255] [Impact Index Per Article: 36.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Skeletal muscle extracts glucose from the blood to maintain demand for carbohydrates as an energy source during exercise. Such uptake involves complex molecular signalling processes that are distinct from those activated by insulin. Exercise-stimulated glucose uptake is preserved in insulin-resistant muscle, emphasizing exercise as a therapeutic cornerstone among patients with metabolic diseases such as diabetes mellitus. Exercise increases uptake of glucose by up to 50-fold through the simultaneous stimulation of three key steps: delivery, transport across the muscle membrane and intracellular flux through metabolic processes (glycolysis and glucose oxidation). The available data suggest that no single signal transduction pathway can fully account for the regulation of any of these key steps, owing to redundancy in the signalling pathways that mediate glucose uptake to ensure maintenance of muscle energy supply during physical activity. Here, we review the molecular mechanisms that regulate the movement of glucose from the capillary bed into the muscle cell and discuss what is known about their integrated regulation during exercise. Novel developments within the field of mass spectrometry-based proteomics indicate that the known regulators of glucose uptake are only the tip of the iceberg. Consequently, many exciting discoveries clearly lie ahead.
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Affiliation(s)
- Lykke Sylow
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Maximilian Kleinert
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
- Institute for Diabetes and Obesity, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
| | - Erik A Richter
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
| | - Thomas E Jensen
- Molecular Physiology Group, Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark
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15
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Cleasby ME, Jamieson PM, Atherton PJ. Insulin resistance and sarcopenia: mechanistic links between common co-morbidities. J Endocrinol 2016; 229:R67-81. [PMID: 26931135 DOI: 10.1530/joe-15-0533] [Citation(s) in RCA: 319] [Impact Index Per Article: 39.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Accepted: 03/01/2016] [Indexed: 12/15/2022]
Abstract
Insulin resistance (IR) in skeletal muscle is a key defect mediating the link between obesity and type 2 diabetes, a disease that typically affects people in later life. Sarcopenia (age-related loss of muscle mass and quality) is a risk factor for a number of frailty-related conditions that occur in the elderly. In addition, a syndrome of 'sarcopenic obesity' (SO) is now increasingly recognised, which is common in older people and is applied to individuals that simultaneously show obesity, IR and sarcopenia. Such individuals are at an increased risk of adverse health events compared with those who are obese or sarcopenic alone. However, there are no licenced treatments for sarcopenia or SO, the syndrome is poorly defined clinically and the mechanisms that might explain a common aetiology are not yet well characterised. In this review, we detail the nature and extent of the clinical syndrome, highlight some of the key physiological processes that are dysregulated and discuss some candidate molecular pathways that could be implicated in both metabolic and anabolic defects in skeletal muscle, with an eye towards future therapeutic options. In particular, the potential roles of Akt/mammalian target of rapamycin signalling, AMP-activated protein kinase, myostatin, urocortins and vitamin D are discussed.
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Affiliation(s)
- Mark E Cleasby
- Department of Comparative Biomedical SciencesRoyal Veterinary College, University of London, London, UK
| | - Pauline M Jamieson
- Centre for Cardiovascular ScienceQueen's Medical Research Institute, University of Edinburgh, Edinburgh, UK
| | - Philip J Atherton
- Division of Medical Sciences and Graduate Entry MedicineUniversity of Nottingham, Medical School, Royal Derby Hospital, Derby, UK
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