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Logesh R, Hari B, Chidambaram K, Das N. Molecular effects of Vitamin-D and PUFAs metabolism in skeletal muscle combating Type-II diabetes mellitus. Gene 2024; 904:148216. [PMID: 38307219 DOI: 10.1016/j.gene.2024.148216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Revised: 01/10/2024] [Accepted: 01/25/2024] [Indexed: 02/04/2024]
Abstract
Multiple post-receptor intracellular alterations such as impaired glucose transfer, glucose phosphorylation, decreased glucose oxidation, and glycogen production contribute to insulin resistance (IR) in skeletal muscle, manifested by diminished insulin-stimulated glucose uptake. Type-2 diabetes mellites (T2DM) has caused by IR, which is also seen in obese patients and those with metabolic syndrome. The Vitamin-D receptor (VDR) and poly unsaturated fatty acids (PUFAs) roles in skeletal muscle growth, shapes, and function for combating type-2 diabetes have been clarified throughout this research. VDR and PUFAs appears to show a variety of effects on skeletal muscle, in addition it shows a promising role on bone and mineral homeostasis. Individuals having T2DM are reported to suffer from severe muscular weakness and alterations in shape of the muscle. Several studies have investigated the effect on VDR on muscular strength and mass, which leads to Vitamin-D deficiency (VDD) in individuals, in which most commonly seen in elderly. VDR has been shown to affect skeletal cellular proliferation, intracellular calcium handling, as well as genomic activity in a variety of different ways such as muscle metabolism, insulin sensitivity, which is the major characteristic pathogenesis for IR in combating T2DM. The identified VDR gene polymorphisms are ApaI, TaqI, FokI, and BsmI that are associated with T2DM. This review collates informations on the mechanisms by which VDR activation takes place in skeletal muscles. Despite the significant breakthroughs made in recent decades, various studies show that IR affects VDR and PUFAs metabolism in skeletal muscle. Therefore, this review collates the data to show the role of VDR and PUFAs in the skeletal muscles to combat T2DM.
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Affiliation(s)
- Rajan Logesh
- Department of Pharmacognosy, JSS College of Pharmacy, Mysuru, JSS Academy of Higher Education & Research, Karnataka, India.
| | - Balaji Hari
- TIFAC CORE in Herbal Drugs, Department of Pharmacognosy, JSS Academy of Higher Education & Research, JSS College of Pharmacy, The Nilgiris, Ooty 643001, Tamil Nadu, India
| | - Kumarappan Chidambaram
- Department of Pharmacology, College of Pharmacy, King Khalid University, Al-Qara, Asir Province, Saudi Arabia
| | - Niranjan Das
- Department of Chemistry, Iswar Chandra Vidyasagar College, Belonia 799155, Tripura, India
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Martínez-Herrera BE, Muñoz-García MG, José-Ochoa LL, Quiroga-Morales LA, Cervántes-González LM, Mireles-Ramírez MA, Delgadillo-Cristerna R, Nuño-Guzmán CM, Leal-Cortés CA, Portilla-de-Buen E, Hernández BT, Gómez-Sánchez E, Velázquez-Flores MC, Salazar-Páramo M, Ochoa-Plascencia MR, Sat-Muñoz D, Balderas-Peña LMA. Role of Incretins in Muscle Functionality, Metabolism, and Body Composition in Breast Cancer: A Metabolic Approach to Understanding This Pathology. Biomedicines 2024; 12:280. [PMID: 38397883 PMCID: PMC10886934 DOI: 10.3390/biomedicines12020280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2023] [Revised: 01/16/2024] [Accepted: 01/24/2024] [Indexed: 02/25/2024] Open
Abstract
A poorly studied issue in women with breast cancer is the role of incretins (GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1)) in the quantity and quality of muscle mass in lean and obese individuals. The current report aims to analyze the patterns of association and the role of incretin in muscle functionality and body composition in women with cancer compared with healthy women (mammography BI-RADS I or II) to elucidate whether GIP and GLP-1 can be used to estimate the risk, in conjunction with overweight or obesity, for breast cancer. We designed a case-control study in women with a breast cancer diagnosis confirmed by biopsy in different clinical stages (CS; n = 87) and healthy women with a mastography BI-RADS I or II within the last year (n = 69). The women were grouped according to body mass index (BMI): lean (<25 kg/m2BS), overweight (≥25-<30 kg/m2BS), and obese (≥30 kg/m2BS). We found that GLP-1 and GIP levels over 18 pg/mL were associated with a risk of breast cancer (GIP OR = 36.5 and GLP-1 OR = 4.16, for the entire sample), particularly in obese women (GIP OR = 8.8 and GLP-1 OR = 6.5), and coincidentally with low muscle quality indexes, showed an association between obesity, cancer, incretin defects, and loss of muscle functionality.
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Affiliation(s)
- Brenda-Eugenia Martínez-Herrera
- Departamento de Nutrición y Dietética, Hospital General de Zona #1, Instituto Mexicano del Seguro Social, OOAD Aguascalientes, Boulevard José María Chavez #1202, Fracc, Lindavista, Aguascalientes 20270, Mexico
| | - Michelle-Guadalupe Muñoz-García
- Carrera de Médico Cirujano y Partero, Coordinación de Servicio Social, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), Guadalajara 44340, Mexico
- Becaria de la Dirección General de Calidad y Educación en Salud, Secretaría de Salud Mexico, Comisión Interinstitucional de Formación de Recursos Humanos en Salud, Programa Nacional de Servicio Social en Investigación 2021, Demarcación Territorial Miguel Hidalgo, Ciudad de Mexico 11410, Mexico
| | - Laura-Liliana José-Ochoa
- Carrera de Médico Cirujano y Partero, Coordinación de Servicio Social, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), Guadalajara 44340, Mexico
| | - Luis-Aarón Quiroga-Morales
- Unidad Académica de Ciencias de la Salud, Clínica de Rehabilitación y Alto Rendimiento ESPORTIVA, Universidad Autónoma de Guadalajara, Zapopan 45129, Mexico
| | - Luz-María Cervántes-González
- Carrera de Médico Cirujano y Partero, Coordinación de Servicio Social, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), Guadalajara 44340, Mexico
- Becaria de la Dirección General de Calidad y Educación en Salud, Secretaría de Salud Mexico, Comisión Interinstitucional de Formación de Recursos Humanos en Salud, Programa Nacional de Servicio Social en Investigación 2021, Demarcación Territorial Miguel Hidalgo, Ciudad de Mexico 11410, Mexico
| | - Mario-Alberto Mireles-Ramírez
- División de Investigación en Salud, Unidad Médica de Alta Especialidad (UMAE), Hospital de Especialidades, Centro Médico Nacional de Occidente, Instituto Mexicano del Seguro Social, 1000 Belisario Domínguez, Guadalajara 44340, Mexico
| | - Raúl Delgadillo-Cristerna
- Unidad Médica de Alta Especialidad (UMAE), Departamento Clínico de Radiologia e Imágen, Hospital de Especialidades (HE), Centro Médico Nacional de Occidente (CMNO), Instituto Mexicano del Seguro Social (IMSS), 1000 Belisario Domínguez, Guadalajara 44340, Mexico
| | - Carlos-M Nuño-Guzmán
- Unidad Médica de Alta Especialidad (UMAE), Departamento Clínico de Cirugía General, División de Cirugía, Hospital de Especialidades, Centro Médico Nacional de Occidente, Instituto Mexicano del Seguro Social, 1000 Belisario Domínguez, Guadalajara 44340, Mexico
- Servicio de Cirugía General, OPD Hospital Civil de Guadalajara "Fray Antonio Alcalde", 278 Hospital, Guadalajara 44280, Mexico
- División de Disciplinas Clínicas, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), 950 Sierra Mojada, Building N, 1st Level, Guadalajara 44340, Mexico
| | - Caridad-Aurea Leal-Cortés
- División de Investigación Quirúrgica, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Órgano de Operación Administrativa Desconcentrada, Guadalajara 44340, Mexico
| | - Eliseo Portilla-de-Buen
- División de Investigación Quirúrgica, Centro de Investigación Biomédica de Occidente, Instituto Mexicano del Seguro Social, Órgano de Operación Administrativa Desconcentrada, Guadalajara 44340, Mexico
| | - Benjamín Trujillo Hernández
- Posgrado en Ciencias Médicas, Universidad de Colima, Av. Universidad No. 333, Las Víboras, Colima 28040, Mexico
| | - Eduardo Gómez-Sánchez
- División de Disciplinas Clínicas, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), 950 Sierra Mojada, Building N, 1st Level, Guadalajara 44340, Mexico
- Cuerpo Académico UDG CA-874 "Ciencias Morfológicas en el Diagnóstico y Tratamiento de la Enfermedad", 950 Sierra Mojada, Gate 7, Building C, 1st Level, Guadalajara 44340, Mexico
| | - Martha-Cecilia Velázquez-Flores
- Departamento de Morfología, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), 950 Sierra Mojada, Gate 7, Building C, 1st Level, Guadalajara 44340, Mexico
- Unidad Médica de Alta Especialidad (UMAE), Departamento Clínico de Anestesiología, División de Cirugía, Hospital de Especialidades, Centro Médico Nacional de Occidente, Instituto Mexicano del Seguro Social, 1000 Belisario Domínguez, Guadalajara 44340, Mexico
| | - Mario Salazar-Páramo
- Academia de Inmunología, Departamento de Fisiología, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), 950 Sierra Mojada, Gate 7, Building O, 1st Level, Guadalajara 44340, Mexico
| | - Miguel-Ricardo Ochoa-Plascencia
- División de Disciplinas Clínicas, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), 950 Sierra Mojada, Building N, 1st Level, Guadalajara 44340, Mexico
- OPD Hospital General de Zapopan, Calle Ramón Corona 500, Colonia Centro, Zapopan 45100, Mexico
| | - Daniel Sat-Muñoz
- Cuerpo Académico UDG CA-874 "Ciencias Morfológicas en el Diagnóstico y Tratamiento de la Enfermedad", 950 Sierra Mojada, Gate 7, Building C, 1st Level, Guadalajara 44340, Mexico
- Departamento de Morfología, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), 950 Sierra Mojada, Gate 7, Building C, 1st Level, Guadalajara 44340, Mexico
- Comité de Cabeza y Cuello, Unidad Médica de Alta Especialidad (UMAE), Hospital de Especialidades, Centro Médico Nacional de Occidente, Instituto Mexicano del Seguro Social, 1000 Belisario Domínguez, Guadalajara 44340, Mexico
- Unidad Médica de Alta Especialidad (UMAE), Departamento Clínico de Oncología Quirúrgica, División de Oncología Hematología, Hospital de Especialidades, Centro Médico Nacional de Occidente, Instituto Mexicano del Seguro Social, 1000 Belisario Domínguez, Guadalajara 44340, Mexico
| | - Luz-Ma-Adriana Balderas-Peña
- Cuerpo Académico UDG CA-874 "Ciencias Morfológicas en el Diagnóstico y Tratamiento de la Enfermedad", 950 Sierra Mojada, Gate 7, Building C, 1st Level, Guadalajara 44340, Mexico
- Departamento de Morfología, Centro Universitario de Ciencias de la Salud (CUCS), Universidad de Guadalajara (UdG), 950 Sierra Mojada, Gate 7, Building C, 1st Level, Guadalajara 44340, Mexico
- Unidad de Investigación Biomédica 02 (UIBM 02), Unidad Médica de Alta Especialidad (UMAE), Hospital de Especialidades (HE), Centro Médico Nacional de Occidente (CMNO), Instituto Mexicano del Seguro Social (IMSS), 1000 Belisario Domínguez, Guadalajara 44340, Mexico
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Alterations in Energy Metabolism, Mitochondrial Function and Redox Homeostasis in GK Diabetic Rat Tissues Treated with Aspirin. LIFE (BASEL, SWITZERLAND) 2022; 12:life12010104. [PMID: 35054496 PMCID: PMC8780217 DOI: 10.3390/life12010104] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Revised: 01/04/2022] [Accepted: 01/10/2022] [Indexed: 11/22/2022]
Abstract
Our recent studies have demonstrated that aspirin treatment prevents inflammatory and oxidative stress-induced alterations in mitochondrial function, improves glucose tolerance and pancreatic endocrine function and preserves tissue-specific glutathione (GSH)-dependent redox homeostasis in Goto-Kakizaki (GK) diabetic rats. In the current study, we have investigated the mechanism of action of aspirin in maintaining mitochondrial bioenergetics and redox metabolism in the liver and kidneys of GK rats. Aspirin reduced the production of reactive oxygen species (ROS) and oxidative stress-induced changes in GSH metabolism. Aspirin treatment also improved mitochondrial respiratory function and energy metabolism, in addition to regulating the expression of cell signaling proteins that were altered in diabetic animals. Ultrastructural electron microscopy studies revealed decreased accumulation of glycogen in the liver of aspirin-treated diabetic rats. Hypertrophic podocytes with irregular fusion of foot processes in the renal glomerulus and detached microvilli, condensed nuclei and degenerated mitochondria observed in the proximal convoluted tubules of GK rats were partially restored by aspirin. These results provide additional evidence to support our previous observation of moderation of diabetic complications by aspirin treatment in GK rats and may have implications for cautious use of aspirin in the therapeutic management of diabetes.
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Insulin-Like Peptide Receptor-Mediated Signaling Pathways Orchestrate Regulation of Growth in the Pacific Oyster ( Crassostrea gigas), as Revealed by Gene Expression Profiles. Int J Mol Sci 2021; 22:ijms22105259. [PMID: 34067636 PMCID: PMC8156652 DOI: 10.3390/ijms22105259] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/09/2021] [Accepted: 05/12/2021] [Indexed: 12/26/2022] Open
Abstract
The involvement of insulin/insulin-like growth factor signaling (IIS) pathways in the growth regulation of marine invertebrates remains largely unexplored. In this study, we used a fast-growing Pacific oyster (Crassostrea gigas) variety “Haida No.1” as the material with which to unravel the role of IIS systems in growth regulation in oysters. Systematic bioinformatics analyses allowed us to identify major components of the IIS signaling pathway and insulin-like peptide receptor (ILPR)-mediated signaling pathways, including PI3K-AKT, RAS-MAPK, and TOR, in C. gigas. The expression levels of the major genes in IIS and its downstream signaling pathways were significantly higher in “Haida No.1” than in wild oysters, suggesting their involvement in the growth regulation of C. gigas. The expression profiles of IIS and its downstream signaling pathway genes were significantly altered by nutrient abundance and culture temperature. These results suggest that the IIS signaling pathway coupled with the ILPR-mediated signaling pathways orchestrate the regulation of energy metabolism to control growth in Pacific oysters.
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Abdul-Ghani MA, Jayyousi A, DeFronzo RA, Asaad N, Al-Suwaidi J. Insulin Resistance the Link between T2DM and CVD: Basic Mechanisms and Clinical Implications. Curr Vasc Pharmacol 2020; 17:153-163. [PMID: 29032755 DOI: 10.2174/1570161115666171010115119] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2017] [Revised: 09/05/2017] [Accepted: 09/27/2017] [Indexed: 01/04/2023]
Abstract
Insulin resistance (IR) is a cardinal feature of type 2 diabetes mellitus (T2DM). It also is associated with multiple metabolic abnormalities which are known cardiovascular disease (CVD) risk factors. Thus, IR not only contributes to the development of hyperglycemia in T2DM patients, but also to the elevated CVD risk. Improving insulin sensitivity is anticipated to both lower the plasma glucose concentration and decrease CVD risk in T2DM patients, independent of glucose control. We review the molecular mechanisms and metabolic consequences of IR in T2DM patients and discuss the importance of addressing IR in the management of T2DM.
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Affiliation(s)
- Muhammad A Abdul-Ghani
- Division of Diabetes, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, United States.,Academic Health System, Hamad Medical Corporation, Doha, Qatar
| | - Amin Jayyousi
- Cardio-Metabolic Institute, Hamad Medical Corporation, Doha, Qatar
| | - Ralph A DeFronzo
- Division of Diabetes, University of Texas Health Science Center at San Antonio, San Antonio, TX, 78229, United States
| | - Nidal Asaad
- Cardio-Metabolic Institute, Hamad Medical Corporation, Doha, Qatar
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Cai WJ, Liang XF, Yuan XC, Li AX, He S. Changes of DNA Methylation Pattern in Metabolic Pathways Induced by High-Carbohydrate Diet Contribute to Hyperglycemia and Fat Deposition in Grass Carp ( Ctenopharyngodon idellus). Front Endocrinol (Lausanne) 2020; 11:398. [PMID: 32754117 PMCID: PMC7381294 DOI: 10.3389/fendo.2020.00398] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 05/18/2020] [Indexed: 12/21/2022] Open
Abstract
Although studies have determined that epigenetics plays an essential role in regulating metabolism in mammals, research on nutrition-related DNA methylation remains to be lacking in teleosts. In the present study, we provided a hepatic whole-genome DNA methylation analysis in grass carp fed with moderate- or excessive-carbohydrate-level diet. Although a high-carbohydrate (HC) diet significantly changed the mRNA expression levels of metabolic genes, it did not affect the global genomic DNA methylation levels in grass carp liver. However, compared with the control group, 3,972 genes were hyper-methylated and 2,904 genes were hypo-methylated in the promoter region. Meanwhile, 10,711 genes were hyper-methylated and 6,764 genes were hypo-methylated in the gene body region in the HC group. These differentially methylated genes (DMGs) were enriched in multiple pathways, including carbohydrate metabolism, insulin pathway, lipid metabolism, and adipocytokine signaling pathway. In addition, the variations in DNA methylation significantly regulated the transcription levels of key genes of metabolism, which could affect the glucose concentrations and the lipid deposition of grass carp. Furthermore, we compared the DNA methylation alterations of genes in glucose metabolism and obesity pathways of grass carp with those of mammalian models in different nutritional states. The results showed that most of the DMGs in grass carp were also regulated by DNA methylation in mammals when the nutritional state changed. The findings revealed more differentially methylated regions and candidate genes for glucose metabolism and broken species boundaries.
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Affiliation(s)
- Wen-Jing Cai
- Chinese Perch Research Center, College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Innovation Base for Chinese Perch Breeding, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, China
| | - Xu-Fang Liang
- Chinese Perch Research Center, College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Innovation Base for Chinese Perch Breeding, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, China
- *Correspondence: Xu-Fang Liang
| | - Xiao-Chen Yuan
- Chinese Perch Research Center, College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Innovation Base for Chinese Perch Breeding, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, China
| | - Ai-Xuan Li
- Chinese Perch Research Center, College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Innovation Base for Chinese Perch Breeding, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, China
| | - Shan He
- Chinese Perch Research Center, College of Fisheries, Huazhong Agricultural University, Wuhan, China
- Innovation Base for Chinese Perch Breeding, Key Lab of Freshwater Animal Breeding, Ministry of Agriculture, Wuhan, China
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Tetramethylpyrazine prevents diabetes by activating PI3K/Akt/GLUT-4 signalling in animal model of type-2 diabetes. Life Sci 2019; 236:116836. [DOI: 10.1016/j.lfs.2019.116836] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Revised: 08/22/2019] [Accepted: 09/03/2019] [Indexed: 12/16/2022]
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Xiang L, Mittwede PN, Clemmer JS. Glucose Homeostasis and Cardiovascular Alterations in Diabetes. Compr Physiol 2015; 5:1815-39. [PMID: 26426468 DOI: 10.1002/cphy.c150001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Czarnecki WM, Podlewska S, Bojarski AJ. Robust optimization of SVM hyperparameters in the classification of bioactive compounds. J Cheminform 2015; 7:38. [PMID: 26273325 PMCID: PMC4534515 DOI: 10.1186/s13321-015-0088-0] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2015] [Accepted: 07/06/2015] [Indexed: 12/12/2022] Open
Abstract
Background Support Vector Machine has become one of the most popular machine learning tools used in virtual screening campaigns aimed at finding new drug candidates. Although it can be extremely effective in finding new potentially active compounds, its application requires the optimization of the hyperparameters with which the assessment is being run, particularly the C and \documentclass[12pt]{minimal}
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\begin{document}$$\gamma$$\end{document}γ values. The optimization requirement in turn, establishes the need to develop fast and effective approaches to the optimization procedure, providing the best predictive power of the constructed model. Results In this study, we investigated the Bayesian and random search optimization of Support Vector Machine hyperparameters for classifying bioactive compounds. The effectiveness of these strategies was compared with the most popular optimization procedures—grid search and heuristic choice. We demonstrated that Bayesian optimization not only provides better, more efficient classification but is also much faster—the number of iterations it required for reaching optimal predictive performance was the lowest out of the all tested optimization methods. Moreover, for the Bayesian approach, the choice of parameters in subsequent iterations is directed and justified; therefore, the results obtained by using it are constantly improved and the range of hyperparameters tested provides the best overall performance of Support Vector Machine. Additionally, we showed that a random search optimization of hyperparameters leads to significantly better performance than grid search and heuristic-based approaches. Conclusions The Bayesian approach to the optimization of Support Vector Machine parameters was demonstrated to outperform other optimization methods for tasks concerned with the bioactivity assessment of chemical compounds. This strategy not only provides a higher accuracy of classification, but is also much faster and more directed than other approaches for optimization. It appears that, despite its simplicity, random search optimization strategy should be used as a second choice if Bayesian approach application is not feasible.The improvement of classification accuracy obtained after the application of Bayesian approach to the optimization of Support Vector Machines parameters. ![]() Electronic supplementary material The online version of this article (doi:10.1186/s13321-015-0088-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Wojciech M Czarnecki
- Faculty of Mathematics and Computer Science, Jagiellonian University, 6 S. Lojasiewicza Street, 30-348 Krakow, Poland
| | - Sabina Podlewska
- Department of Medicinal Chemistry, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland ; Faculty of Chemistry, Jagiellonian University, 3 Ingardena Street, 30-060 Krakow, Poland
| | - Andrzej J Bojarski
- Department of Medicinal Chemistry, Institute of Pharmacology, Polish Academy of Sciences, 12 Smetna Street, 31-343 Krakow, Poland
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Pyruvate dehydrogenase kinase 4 (PDK4) could be involved in a regulatory role in apoptosis and a link between apoptosis and insulin resistance. Exp Mol Pathol 2015; 98:574-84. [DOI: 10.1016/j.yexmp.2015.03.022] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 03/16/2015] [Indexed: 12/14/2022]
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11
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Chang CI, Chou CH, Liao MH, Chen TM, Cheng CH, Anggriani R, Tsai CP, Tseng HI, Cheng HL. Bitter melon triterpenes work as insulin sensitizers and insulin substitutes in insulin-resistant cells. J Funct Foods 2015. [DOI: 10.1016/j.jff.2014.12.050] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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Exploiting uncertainty measures in compounds activity prediction using support vector machines. Bioorg Med Chem Lett 2014; 25:100-5. [PMID: 25466199 DOI: 10.1016/j.bmcl.2014.11.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Revised: 10/31/2014] [Accepted: 11/01/2014] [Indexed: 11/23/2022]
Abstract
The great majority of molecular modeling tasks require the construction of a model that is then used to evaluate new compounds. Although various types of these models exist, at some stage, they all use knowledge about the activity of a given group of compounds, and the performance of the models is dependent on the quality of these data. Biological experiments verifying the activity of chemical compounds are often not reproducible; hence, databases containing these results often possess various activity records for a given molecule. In this study, we developed a method that incorporates the uncertainty of biological tests in machine-learning-based experiments using the Support Vector Machine as a classification model. We show that the developed methodology improves the classification effectiveness in the tested conditions.
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Chang CI, Hsu CM, Li TS, Huang SD, Lin CC, Yen CH, Chou CH, Cheng HL. Constituents of the stem of Cucurbita moschata exhibit antidiabetic activities through multiple mechanisms. J Funct Foods 2014. [DOI: 10.1016/j.jff.2014.06.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
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Capiotti KM, Antonioli R, Kist LW, Bogo MR, Bonan CD, Da Silva RS. Persistent impaired glucose metabolism in a zebrafish hyperglycemia model. Comp Biochem Physiol B Biochem Mol Biol 2014; 171:58-65. [PMID: 24704522 DOI: 10.1016/j.cbpb.2014.03.005] [Citation(s) in RCA: 91] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2013] [Revised: 03/12/2014] [Accepted: 03/27/2014] [Indexed: 11/30/2022]
Abstract
Diabetes mellitus (DM) affects over 10% of the world's population. Hyperglycemia is the main feature for the diagnosis of this disease. The zebrafish (Danio rerio) is an established model organism for the study of various metabolic diseases. In this paper, hyperglycemic zebrafish, when immersed in a 111 mM glucose solution for 14 days, developed increased glycation of proteins from the eyes, decreased mRNA levels of insulin receptors in the muscle, and a reversion of high blood glucose level after treatment with anti-diabetic drugs (glimepiride and metformin) even after 7 days of glucose withdrawal. Additionally, hyperglycemic zebrafish developed an impaired response to exogenous insulin, which was recovered after 7 days of glucose withdrawal. These data suggest that the exposure of adult zebrafish to high glucose concentration is able to induce persistent metabolic changes probably underlined by a hyperinsulinemic state and impaired peripheral glucose metabolism.
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Affiliation(s)
- Katiucia Marques Capiotti
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil; Instituto Nacional de Ciência e Tecnologia Translacional em Medicina (INCT-TM), 90035-003 Porto Alegre, RS, Brazil.
| | - Régis Antonioli
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil; Instituto Nacional de Ciência e Tecnologia Translacional em Medicina (INCT-TM), 90035-003 Porto Alegre, RS, Brazil.
| | - Luiza Wilges Kist
- Laboratório de Biologia Genômica e Molecular, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil; Instituto Nacional de Ciência e Tecnologia Translacional em Medicina (INCT-TM), 90035-003 Porto Alegre, RS, Brazil.
| | - Maurício Reis Bogo
- Laboratório de Biologia Genômica e Molecular, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil; Instituto Nacional de Ciência e Tecnologia Translacional em Medicina (INCT-TM), 90035-003 Porto Alegre, RS, Brazil.
| | - Carla Denise Bonan
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil; Instituto Nacional de Ciência e Tecnologia Translacional em Medicina (INCT-TM), 90035-003 Porto Alegre, RS, Brazil.
| | - Rosane Souza Da Silva
- Laboratório de Neuroquímica e Psicofarmacologia, Departamento de Biologia Celular e Molecular, Faculdade de Biociências, PUCRS, Porto Alegre, RS, Brazil; Instituto Nacional de Ciência e Tecnologia Translacional em Medicina (INCT-TM), 90035-003 Porto Alegre, RS, Brazil.
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15
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Blake R, Trounce IA. Mitochondrial dysfunction and complications associated with diabetes. Biochim Biophys Acta Gen Subj 2014; 1840:1404-12. [DOI: 10.1016/j.bbagen.2013.11.007] [Citation(s) in RCA: 105] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2013] [Revised: 10/18/2013] [Accepted: 11/06/2013] [Indexed: 02/06/2023]
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16
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Yao ZG, Liu Y, Zhang L, Huang L, Ma CM, Xu YF, Zhu H, Qin C. Co-location of HDAC2 and insulin signaling components in the adult mouse hippocampus. Cell Mol Neurobiol 2012; 32:1337-42. [PMID: 22733364 PMCID: PMC11498477 DOI: 10.1007/s10571-012-9859-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Accepted: 06/05/2012] [Indexed: 01/15/2023]
Abstract
As one part of epigenetics, histone deacetylases (HDACs) have been demonstrated to get into the neural events, including neurogenesis, synaptic plasticity, and neurodegeneration through regulating acetylation status of target proteins to influence protein function and gene expression. However, the recent studies indicated that HDAC2, a member of HDACs family, played a role in insulin signaling pathway and synaptic plasticity. Here, we are concerned about whether HDAC2 was co-located with insulin signaling components in postsynaptic glutamatergic neurons (PSGNs) of the adult mouse hippocampus using double immunofluorescence staining. The results displayed that HDAC2 was present in PSGNs marked by N-methyl-D-aspartate receptor subunit 2B, in which major components of insulin signaling pathway such as insulin receptor alpha and beta and insulin receptor substrate-1 were also involved. Accordingly, we speculate that the interaction of HDAC2 and insulin signaling system in PSGNs observed in the present study may serve as a potential mechanism in memory formation. We hope this could provide a valuable basis for understanding the roles of HDAC2 and insulin on cognitive impairment of diabetes mellitus, involved Alzheimer's disease, which is also called type 3 diabetes recently. And this will also benefit to the treatment of insulin-related diseases in the central nervous system.
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Affiliation(s)
- Zhi-Gang Yao
- Comparative Medical Center, Institute of Laboratory Animal Science, Peking Union Medical College (PUMC), Panjiayuan Nanli No. 5, Chaoyang District, Beijing, 100021 China
- Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Beijing, China
- Key Laboratory of Human Diseases Animal Model, State Administration of Traditional Chinese Medicine, Beijing, China
| | - Yu Liu
- Comparative Medical Center, Institute of Laboratory Animal Science, Peking Union Medical College (PUMC), Panjiayuan Nanli No. 5, Chaoyang District, Beijing, 100021 China
- Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Beijing, China
- Key Laboratory of Human Diseases Animal Model, State Administration of Traditional Chinese Medicine, Beijing, China
| | - Ling Zhang
- Comparative Medical Center, Institute of Laboratory Animal Science, Peking Union Medical College (PUMC), Panjiayuan Nanli No. 5, Chaoyang District, Beijing, 100021 China
- Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Beijing, China
- Key Laboratory of Human Diseases Animal Model, State Administration of Traditional Chinese Medicine, Beijing, China
| | - Lan Huang
- Comparative Medical Center, Institute of Laboratory Animal Science, Peking Union Medical College (PUMC), Panjiayuan Nanli No. 5, Chaoyang District, Beijing, 100021 China
- Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Beijing, China
- Key Laboratory of Human Diseases Animal Model, State Administration of Traditional Chinese Medicine, Beijing, China
| | - Chun-Mei Ma
- Comparative Medical Center, Institute of Laboratory Animal Science, Peking Union Medical College (PUMC), Panjiayuan Nanli No. 5, Chaoyang District, Beijing, 100021 China
- Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Beijing, China
- Key Laboratory of Human Diseases Animal Model, State Administration of Traditional Chinese Medicine, Beijing, China
| | - Yan-Feng Xu
- Comparative Medical Center, Institute of Laboratory Animal Science, Peking Union Medical College (PUMC), Panjiayuan Nanli No. 5, Chaoyang District, Beijing, 100021 China
- Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Beijing, China
- Key Laboratory of Human Diseases Animal Model, State Administration of Traditional Chinese Medicine, Beijing, China
| | - Hua Zhu
- Comparative Medical Center, Institute of Laboratory Animal Science, Peking Union Medical College (PUMC), Panjiayuan Nanli No. 5, Chaoyang District, Beijing, 100021 China
- Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Beijing, China
- Key Laboratory of Human Diseases Animal Model, State Administration of Traditional Chinese Medicine, Beijing, China
| | - Chuan Qin
- Comparative Medical Center, Institute of Laboratory Animal Science, Peking Union Medical College (PUMC), Panjiayuan Nanli No. 5, Chaoyang District, Beijing, 100021 China
- Key Laboratory of Human Disease Comparative Medicine, Ministry of Health, Beijing, China
- Key Laboratory of Human Diseases Animal Model, State Administration of Traditional Chinese Medicine, Beijing, China
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17
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Zanou N, Schakman O, Louis P, Ruegg UT, Dietrich A, Birnbaumer L, Gailly P. Trpc1 ion channel modulates phosphatidylinositol 3-kinase/Akt pathway during myoblast differentiation and muscle regeneration. J Biol Chem 2012; 287:14524-34. [PMID: 22399301 DOI: 10.1074/jbc.m112.341784] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
We previously showed in vitro that calcium entry through Trpc1 ion channels regulates myoblast migration and differentiation. In the present work, we used primary cell cultures and isolated muscles from Trpc1(-/-) and Trpc1(+/+) murine model to investigate the role of Trpc1 in myoblast differentiation and in muscle regeneration. In these models, we studied regeneration consecutive to cardiotoxin-induced muscle injury and observed a significant hypotrophy and a delayed regeneration in Trpc1(-/-) muscles consisting in smaller fiber size and increased proportion of centrally nucleated fibers. This was accompanied by a decreased expression of myogenic factors such as MyoD, Myf5, and myogenin and of one of their targets, the developmental MHC (MHCd). Consequently, muscle tension was systematically lower in muscles from Trpc1(-/-) mice. Importantly, the PI3K/Akt/mTOR/p70S6K pathway, which plays a crucial role in muscle growth and regeneration, was down-regulated in regenerating Trpc1(-/-) muscles. Indeed, phosphorylation of both Akt and p70S6K proteins was decreased as well as the activation of PI3K, the main upstream regulator of the Akt. This effect was independent of insulin-like growth factor expression. Akt phosphorylation also was reduced in Trpc1(-/-) primary myoblasts and in control myoblasts differentiated in the absence of extracellular Ca(2+) or pretreated with EGTA-AM or wortmannin, suggesting that the entry of Ca(2+) through Trpc1 channels enhanced the activity of PI3K. Our results emphasize the involvement of Trpc1 channels in skeletal muscle development in vitro and in vivo, and identify a Ca(2+)-dependent activation of the PI3K/Akt/mTOR/p70S6K pathway during myoblast differentiation and muscle regeneration.
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Affiliation(s)
- Nadège Zanou
- Laboratory of Cell Physiology, Institute of Neuroscience, Université Catholique de Louvain, 55/40 av. Hippocrate, 1200 Brussels, Belgium.
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18
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Axl is essential for VEGF-A-dependent activation of PI3K/Akt. EMBO J 2012; 31:1692-703. [PMID: 22327215 DOI: 10.1038/emboj.2012.21] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 01/16/2012] [Indexed: 01/07/2023] Open
Abstract
Herein, we report that vascular endothelial growth factor A (VEGF-A) engages the PI3K/Akt pathway by a previously unknown mechanism that involves three tyrosine kinases. Upon VEGF-A-dependent activation of VEGF receptor-2 (VEGFR-2), and subsequent TSAd-mediated activation of Src family kinases (SFKs), SFKs engage the receptor tyrosine kinase Axl via its juxtamembrane domain to trigger ligand-independent autophosphorylation at a pair of YXXM motifs that promotes association with PI3K and activation of Akt. Other VEGF-A-mediated signalling pathways are independent of Axl. Interfering with Axl expression or function impairs VEGF-A- but not bFGF-dependent migration of endothelial cells. Similarly, Axl null mice respond poorly to VEGF-A-induced vascular permeability or angiogenesis, whereas other agonists induce a normal response. These results elucidate the mechanism by which VEGF-A activates PI3K/Akt, and identify previously unappreciated potential therapeutic targets of VEGF-A-driven processes.
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Colombatti A, Russo P, Cervi M, Bogetto L, Wassermann B, Mainiero F, Spessotto P. Differential Expression of IRS-1 and IRS-2 in Uterine Leiomyosarcomas with Distinct Oncogenic Phenotypes: Lack of Correlation with Downstream Signaling Events. Sarcoma 2011; 6:89-96. [PMID: 18521338 PMCID: PMC2395487 DOI: 10.1080/1357714021000065387] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Purpose: Insulin receptor substrates (IRSs) are essential for insulin-induced mitogenic effects on several cell types but they
also are involved in cell transformation.We investigated whether the differential constitutive expression and potential distinct
downstream signaling events of IRS-1 and IRS-2 might be related to discrete tumourigenic phenotypes of three human
uterine leiomyosarcoma cell lines, one of which was specifically isolated for the present study. Methods and results: SK-UT-1B egressed effectively from a gellyfied Matrigel matrix and grew as did DMR cells in an
anchorage-independent manner in agar and induced rapidly growing tumours in nude mice. On the contrary, SK-LMS-1
cells did not emigrate from Matrigel, neither grew in agar nor were they tumourigenic. IRS-2 was highly expressed in the
more malignant cell lines, whereas IRS-1 was present only in SK-LMS-1 cells. However, upon insulin stimulation both IRS-
1 and IRS-2 were tyrosine phosphorylated with a similar kinetic in the respective cell lines; furthermore, after 1 min of
insulin stimulation PI3-kinase associated with IRSs and after 2 min Shc was phosphorylated and associated with Grb2 with
minor differences detectable among the various cell lines in the duration of phosphorylation and/or in their association irrespective
of whether IRS-1 or IRS-2 were expressed. Discussion: Our findings tend to exclude that the malignancy displayed by uterine leiomyosarcomas might be directly linked
to the activation of distinct IRS-1- or IRS-2-dependent pathways.
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Affiliation(s)
- Alfonso Colombatti
- Divisione di Oncologia Sperimentale 2 Centro di Riferimento Oncologico-IRCCS Aviano 33081 Italy
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Anand S, Muthusamy V, Sujatha S, Sangeetha K, Bharathi Raja R, Sudhagar S, Poornima Devi N, Lakshmi B. Aloe emodin glycosides stimulates glucose transport and glycogen storage through PI3K dependent mechanism in L6 myotubes and inhibits adipocyte differentiation in 3T3L1 adipocytes. FEBS Lett 2010; 584:3170-8. [DOI: 10.1016/j.febslet.2010.06.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 05/14/2010] [Accepted: 06/04/2010] [Indexed: 11/29/2022]
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21
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Pathogenesis of insulin resistance in skeletal muscle. J Biomed Biotechnol 2010; 2010:476279. [PMID: 20445742 PMCID: PMC2860140 DOI: 10.1155/2010/476279] [Citation(s) in RCA: 397] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 01/20/2010] [Indexed: 12/16/2022] Open
Abstract
Insulin resistance in skeletal muscle is manifested by decreased insulin-stimulated glucose uptake and results from impaired insulin signaling and multiple post-receptor intracellular defects including impaired glucose transport, glucose phosphorylation, and reduced glucose oxidation and glycogen synthesis. Insulin resistance is a core defect in type 2 diabetes, it is also associated with obesity and the metabolic syndrome. Dysregulation of fatty acid metabolism plays a pivotal role in the pathogenesis of insulin resistance in skeletal muscle. Recent studies have reported a mitochondrial defect in oxidative phosphorylation in skeletal muscle in variety of insulin resistant states. In this review, we summarize the cellular and molecular defects that contribute to the development of insulin resistance in skeletal muscle.
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O'Brien K, Sekimoto H, Boney C, Malee M. Effect of fetal dexamethasone exposure on the development of adult insulin sensitivity in a rat model. J Matern Fetal Neonatal Med 2009; 21:623-8. [DOI: 10.1080/14767050802213073] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Abstract
The definition of mitogenic activity of insulin is controversial. Under physiological conditions, mitogenic refers to cell proliferation and tissue repair. In pathological conditions, it may refer to stimulation of tumour cells in pre-existing (undiagnosed) tumours. The in vitro investigations using benign and malignant cell lines compare proliferative activity of insulin molecules (animal, human and analogues). In these studies, inclusion of [B10-Asp] insulin would be a valuable link to the existing evidence on proliferation of mammary tissue in rodents. Animal and human insulin have growth promoting activity on spontaneously arising tumours (e.g. mammary tumours in rodents). They have no carcinogenic activity (cell transformation), and moreover insulin is not a co-carcinogen when evaluated in special toxicology. Mitogenicity (growth promoting activity) of insulin may be a problem in people with undiagnosed tumours, and may require definition of patient groups who would benefit from targeted monitoring.
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Affiliation(s)
- Juergen Sandow
- Centre of Pharmacology, Johann-Wolfgang-Goethe University, Frankfurt-Main, Germany.
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24
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Yamamoto S, Ichishima K, Ehara T. Reduced volume-regulated outwardly rectifying anion channel activity in ventricular myocyte of type 1 diabetic mice. J Physiol Sci 2009; 59:87-96. [PMID: 19340548 PMCID: PMC10717248 DOI: 10.1007/s12576-008-0012-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2008] [Accepted: 11/14/2008] [Indexed: 12/20/2022]
Abstract
The currents through the volume-regulated outwardly rectifying anion channel (VRAC) were measured in single ventricular myocytes obtained from streptozotocin (STZ)-induced diabetic mice, using whole-cell voltage-clamp method. In myocytes from STZ-diabetic mice, the density of VRAC current induced by hypotonic perfusion was markedly reduced, compared with that in the cells form normal control mice. Video-image analysis showed that the regulatory volume decrease (RVD), which was seen in normal cells after osmotic swelling, was almost lost in myocytes from STZ-diabetic mice. Some mice were pretreated with 3-O-methylglucose before STZ injection, to prevent the STZ's beta cell toxicity. In the myocytes obtained from such mice, the magnitude of VRAC current and the degree of RVD seen during hypotonic challenge were almost normal. Incubation of the myocytes from STZ-diabetic mice with insulin reversed the attenuation of VRAC current. These findings suggested that the STZ-induced chronic insulin-deficiency was an important causal factor for the attenuation of VRAC current. Intracellular loading of the STZ-diabetic myocytes with phosphatidylinositol 3,4,5-trisphosphate (PIP3), but not phosphatidylinositol 4,5-bisphosphate (PIP2), also reversed the attenuation of VRAC current. Furthermore, treatment of the normal cells with wortmannin, a phosphatidylinositol 3-kinase (PI3K) inhibitor, suppressed the development of VRAC current. We postulate that an impairment PI3K-PIP3 pathway, which may be insulin-dependent, is responsible for the attenuation of VRAC currents in STZ-diabetic myocytes.
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Affiliation(s)
- Shintaro Yamamoto
- Department of Physiology, Saga University Faculty of Medicine, 5-1-1 Nabeshima, Saga, 849-8501, Japan.
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25
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Papaconstantinou J. Insulin/IGF-1 and ROS signaling pathway cross-talk in aging and longevity determination. Mol Cell Endocrinol 2009; 299:89-100. [PMID: 19103250 PMCID: PMC2873688 DOI: 10.1016/j.mce.2008.11.025] [Citation(s) in RCA: 81] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/13/2008] [Revised: 11/11/2008] [Accepted: 11/12/2008] [Indexed: 01/29/2023]
Abstract
Regulation of hormonal, insulin/IGF-1 (Ins/IGF-1) signaling activities, and pathways of the intrinsic generation of reactive oxygen species (ROS) play a role in aging and longevity determination. In this review we discuss the cross-talk between these pathways as mechanisms of signaling that may be important factors in the regulation of aging and longevity. The balance of physiological processes controlling the rate of aging and longevity in several mouse mutants suggests the involvement of cross-talk mechanisms of regulation of the insulin/IGF1 signaling pathway vs. the ROS signaling pathways. In mice, modulation of the Ins/IGF-1 signaling pathways resulting from the Prop1(df), Pit1(dw) and Igf1 receptor mutations exemplify the hormonal pathways associated with aging and longevity determination. These pathways are also targets of the ROS-mediated redox pathways. Similarly, the Klotho and p66(Shc) mutants link regulation of ROS signaling pathways to aging and longevity determination. Both of these models also display altered insulin signaling activity, a characteristic associated with longevity. The Ins/IGF-1 signaling pathway is of particular interest because of its decreased activity due to genetic manipulation vs. its responsiveness to ROS levels.
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Affiliation(s)
- John Papaconstantinou
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, 301 University Blvd, Mail Route 0643, Galveston, TX 77555-0643, United States.
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26
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Cloning, chromosomal localization, SNP detection and association analysis of the porcine IRS-1 gene. Mol Biol Rep 2008; 36:2087-92. [DOI: 10.1007/s11033-008-9420-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2008] [Accepted: 12/03/2008] [Indexed: 10/21/2022]
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27
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Xu J, Kim HT, Ma Y, Zhao L, Zhai L, Kokorina N, Wang P, Messina JL. Trauma and hemorrhage-induced acute hepatic insulin resistance: dominant role of tumor necrosis factor-alpha. Endocrinology 2008; 149:2369-82. [PMID: 18187553 PMCID: PMC2329283 DOI: 10.1210/en.2007-0922] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
It has long been known that injury, infections, and other critical illnesses are often associated with hyperglycemia and hyperinsulinemia. Mortality of critically ill patients is greatly reduced by intensive insulin therapy, suggesting the significance of reversing or compensating for the development of acute insulin resistance. However, the development of acute injury/infection-induced insulin resistance is poorly studied, much less than the chronic diseases associated with insulin resistance, such as type 2 diabetes and obesity. We previously found that insulin resistance develops acutely in the liver after trauma and hemorrhage. The present study was designed to begin to understand the first steps in the development of trauma and hemorrhage-induced acute hepatic insulin resistance in an animal model of injury and blood loss similar to traumatic or surgical injury and hemorrhage. We present novel data that indicate that hepatic insulin resistance increased dramatically with an increasing extent of hemorrhage. With increasing extent of blood loss, there were increases in serum TNF-alpha levels, phosphorylation of liver insulin receptor substrate-1 on serine 307, and liver c-Jun N-terminal kinase activation/phosphorylation. Exogenous TNF-alpha infusion increased c-Jun N-terminal kinase phosphorylation and insulin receptor substrate-1 serine 307 phosphorylation, and inhibited insulin-induced signaling in liver. Conversely, neutralizing TNF-alpha antibody treatment reversed many of the hemorrhage-induced changes in hepatic insulin signaling. Our data indicate that the acute development of insulin resistance after trauma and hemorrhage may have some similarities to the insulin resistance that occurs in chronic diseases. However, because so little is known about this acute insulin-resistant state, much more needs to be done before we can attain a level of understanding similar to that of chronic states of insulin resistance.
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Affiliation(s)
- Jie Xu
- Department of Pathology, Division of Molecular and Cellular Pathology, The University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA
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Yu W, Chen Z, Zhang J, Zhang L, Ke H, Huang L, Peng Y, Zhang X, Li S, Lahn BT, Xiang AP. Critical role of phosphoinositide 3-kinase cascade in adipogenesis of human mesenchymal stem cells. Mol Cell Biochem 2007; 310:11-8. [PMID: 18060476 DOI: 10.1007/s11010-007-9661-9] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2007] [Accepted: 11/14/2007] [Indexed: 01/13/2023]
Abstract
Mesenchymal stem cells (MSCs) are multipotent stem cells capable of differentiating into adipocytes in the presence of a hormone cocktail. These cells thus provide a promising model for studying the early events of adipogenesis. Here, we examine the involvement of the PI3K/Akt and mTOR/p70S6K signaling pathways in human MSC adipogenesis. We found that the two pathways were strongly activated with a similar temporal profile under the adipogenesis-inducing hormone cocktail and this activation could be blocked by LY294002, a specific inhibitor of PI3K. Furthermore, rapamycin, a specific inhibitor of mTOR, blocked the activation of mTOR/p70S6K but not PI3K/Akt. Both LY294002 and rapamycin severely suppressed lipid accumulation, as well as the expression of adipogenic markers, including PPAR gamma 2 and C/EBP alpha, two master adipogenic transcription factors. Together, these data indicate that the mTOR/p70S6K pathway acts downstream of the PI3K/Akt pathway in mediating the adipogenic conversion of MSCs. In conclusion, our data suggest that the PI3K/Akt and mTOR/p70S6K signaling pathways are essential for adipogenesis of human MSCs.
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Affiliation(s)
- Weihua Yu
- Center for Stem Cell Biology and Tissue Engineering, Sun Yat-sen University, 74 Zhongshan Road 2, Guangzhou, Guangdong 510080, PR China
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Lee YS, Shin S, Shigihara T, Hahm E, Liu MJ, Han J, Yoon JW, Jun HS. Glucagon-like peptide-1 gene therapy in obese diabetic mice results in long-term cure of diabetes by improving insulin sensitivity and reducing hepatic gluconeogenesis. Diabetes 2007; 56:1671-9. [PMID: 17369525 DOI: 10.2337/db06-1182] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Long-term treatment with glucagon-like peptide (GLP)-1 or its analog can improve insulin sensitivity. However, continuous administration is required due to its short half-life. We hypothesized that continuous production of therapeutic levels of GLP-1 in vivo by a gene therapy strategy may remit hyperglycemia and maintain prolonged normoglycemia. We produced a recombinant adenovirus expressing GLP-1 (rAd-GLP-1) under the cytomegalovirus promoter, intravenously injected it into diabetic ob/ob mice, and investigated the effect of this treatment on remission of diabetes, as well as the mechanisms involved. rAd-GLP-1-treated diabetic ob/ob mice became normoglycemic 4 days after treatment, remained normoglycemic over 60 days, and had reduced body weight gain. Glucose tolerance tests found that exogenous glucose was cleared normally. rAd-GLP-1-treated diabetic ob/ob mice showed improved beta-cell function, evidenced by glucose-responsive insulin release, and increased insulin sensitivity, evidenced by improved insulin tolerance and increased insulin-stimulated glucose uptake in adipocytes. rAd-GLP-1 treatment increased basal levels of insulin receptor substrate (IRS)-1 in the liver and activation of IRS-1 and protein kinase C by insulin in liver and muscle; increased Akt activation was only observed in muscle. rAd-GLP-1 treatment reduced hepatic glucose production and hepatic expression of phosphoenolpyruvate carboxykinase, glucose-6-phosphatase, and fatty acid synthase in ob/ob mice. Taken together, these results show that a single administration of rAd-GLP-1 results in the long-term remission of diabetes in ob/ob mice by improving insulin sensitivity through restoration of insulin signaling and reducing hepatic gluconeogenesis.
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Affiliation(s)
- Young-Sun Lee
- Rosalind Franklin Comprehensive Diabetes Center, Department of Pathology, Chicago Medical School, North Chicago, IL 60064, USA
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Kim W, Khil LY, Clark R, Bok SH, Kim EE, Lee S, Jun HS, Yoon JW. Naphthalenemethyl ester derivative of dihydroxyhydrocinnamic acid, a component of cinnamon, increases glucose disposal by enhancing translocation of glucose transporter 4. Diabetologia 2006; 49:2437-48. [PMID: 16896937 DOI: 10.1007/s00125-006-0373-6] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/26/2006] [Accepted: 06/01/2006] [Indexed: 01/31/2023]
Abstract
AIMS/HYPOTHESIS Cinnamon extracts have anti-diabetic effects. Phenolic acids, including hydrocinnamic acids, were identified as major components of cinnamon extracts. Against this background we sought to develop a new anti-diabetic compound using derivatives of hydroxycinnamic acids purified from cinnamon. METHODS We purified hydroxycinnamic acids from cinnamon, synthesised a series of derivatives, and screened them for glucose transport activity in vitro. We then selected the compound with the highest glucose transport activity in epididymal adipocytes isolated from male Sprague-Dawley rats in vitro, tested it for glucose-lowering activity in vivo, and studied the mechanisms involved. RESULTS A naphthalenemethyl ester of 3,4-dihydroxyhydrocinnamic acid (DHH105) showed the highest glucose transport activity in vitro. Treatment of streptozotocin-induced diabetic C57BL/6 mice and spontaneously diabetic ob/ob mice with DHH105 decreased blood glucose levels to near normoglycaemia. Further studies revealed that DHH105 increased the maximum speed of glucose transport and the translocation of glucose transporter 4 (GLUT4, now known as solute carrier family 2 [facilitated glucose transporter], member 4 [SLC2A4]) in adipocytes, resulting in increased glucose uptake. In addition, DHH105 enhanced phosphorylation of the insulin receptor-beta subunit and insulin receptor substrate-1 in adipocytes, both in vitro and in vivo. This resulted in the activation of phosphatidylinositol 3-kinase and Akt/protein kinase B, contributing to the translocation of GLUT4 to the plasma membrane. CONCLUSIONS/INTERPRETATION We conclude that DHH105 lowers blood glucose levels through the enhancement of glucose transport, mediated by an increase in insulin-receptor signalling. DHH105 may be a valuable candidate for a new anti-diabetic drug.
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Affiliation(s)
- W Kim
- Julia McFarlane Diabetes Research Centre and Department of Microbiology and Infectious Diseases, Faculty of Medicine, University of Calgary, Calgary, AB, Canada
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Hunker CM, Kruk I, Hall J, Giambini H, Veisaga ML, Barbieri MA. Role of Rab5 in insulin receptor-mediated endocytosis and signaling. Arch Biochem Biophys 2006; 449:130-42. [PMID: 16554017 DOI: 10.1016/j.abb.2006.01.020] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2005] [Revised: 01/25/2006] [Accepted: 01/25/2006] [Indexed: 10/24/2022]
Abstract
Activated insulin receptors recruit various intracellular proteins leading to signal generation and endocytic trafficking. Although activated receptors are rapidly internalized into the endocytic compartment and subsequently degraded in lysosomes, the linkage between insulin receptor signaling and endocytosis is not well understood. This study utilizes both overexpression and depletion of Rab5 proteins to show that they play a critical role in both insulin-stimulated fluid phase and receptor-mediated endocytosis. Specifically, Rab5:WT and Rab5:Q79L (a GTP-hydrolysis defective mutant) enhance both types of endocytosis in response to insulin, while Rab5:S34N (a GTP-binding defective mutant) has the opposite effect. Morphological analysis indicates that both Rab5 and insulin receptor are found on early endosomes, but not at the plasma membrane. In addition, expression of Rab5:WT and Rab5:Q79L enhance both Erk1/2 and Akt activation without affecting JN- and p38-kinase activities, while the expression of Rab5:S34N blocks both Erk1/2 and Akt activation. Consistent with these observations, DNA synthesis is also altered by the expression of Rab5:S34N. Taken together, these results demonstrate that Rab5 is required for insulin receptor membrane trafficking and signaling.
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Affiliation(s)
- C M Hunker
- Department of Biological Sciences, Florida International University, University Park, Miami, FL 33199, USA
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Isenovic ER, Zakula Z, Koricanac G, Ribarac-Stepic N. Insulin modulates rat liver glucocorticoid receptor. ACTA BIOLOGICA HUNGARICA 2006; 57:37-48. [PMID: 16646523 DOI: 10.1556/abiol.57.2006.1.4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This investigation used cytosol fraction of rat liver to examine the effects of insulin (INS) on functional properties of glucocorticoid receptor (GR). Male Wistar rats (220-250 g b.wt.) were injected with INS (50 microg/200 g b.wt, i.p.) and 18 h after INS administration used for experiments. INS-stimulated dissociation of G-R complexes was significantly increased by 133% compared to control level. However, INS treatment significantly stimulated stability of GR protein by 138% above control value. Furthermore, results show that INS stimulated activation of formed cytosol [3H] TA-R complexes by 143% in respect to control. [3H]TA-R complexes from INS treated animals could be activated and accumulated at higher rate in cell nuclei of control animals. The physiological relevance of the data was confirmed by INS-related stimulation of Tryptophan oxigenase (TO) activity. It was observed that INS stimulated TO activity while INS injected to adrenalectomized rats, exhibited less effects compared to control. The results indicate that a glucocorticoid hormone (CORT) enhances INS induced stimulation of TO activity, as evidenced by enhanced enzyme activity. Presented data suggest: that INS treatment leads to modifications of the GR protein and the nuclear components and that INS activates the rat liver CORT signaling pathway which mediates, in part, the activity of TO.
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Affiliation(s)
- Esma R Isenovic
- Department for Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, 11000 Belgrade, Serbia and Montenegro.
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Hunker CM, Giambini H, Galvis A, Hall J, Kruk I, Veisaga ML, Barbieri MA. Rin1 regulates insulin receptor signal transduction pathways. Exp Cell Res 2006; 312:1106-18. [PMID: 16457816 DOI: 10.1016/j.yexcr.2005.12.021] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Revised: 12/21/2005] [Accepted: 12/21/2005] [Indexed: 10/25/2022]
Abstract
Rin1 is a multifunctional protein containing several domains, including Ras binding and Rab5 GEF domains. The role of Rin1 in insulin receptor internalization and signaling was examined by expressing Rin1 and deletion mutants in cells utilizing a retrovirus system. Here, we show that insulin-receptor-mediated endocystosis and fluid phase insulin-stimulated endocytosis are enhanced in cells expressing the Rin1:wild type and the Rin1:C deletion mutant, which contain both the Rab5-GEF and GTP-bound Ras binding domains. However, the Rin1:N deletion mutant, which contains both the SH2 and proline-rich domains, blocked insulin-stimulated receptor-mediated and insulin-stimulated fluid phase endocytosis. In addition, the expression of Rin1:delta (429-490), a natural occurring splice variant, also blocked both receptor-mediated and fluid phase endocystosis. Furthermore, association of the Rin1 SH2 domain with the insulin receptor was dependent on tyrosine phosphorylation of the insulin receptor. Morphological analysis indicates that Rin1 co-localizes with insulin receptor both at the cell surface and in endosomes upon insulin stimulation. Interestingly, the expression of Rin1:wild type and both deletion mutants blocks the activation of Erk1/2 and Akt1 kinase activities without affecting either JN or p38 kinase activities. DNA synthesis and Elk-1 activation are also altered by the expression of Rin1:wild type and the Rin1:C deletion mutant. In contrast, the expression of Rin1:delta stimulates both Erk1/2 and Akt1 activation, DNA synthesis and Elk-1 activation. These results demonstrate that Rin1 plays an important role in both insulin receptor membrane trafficking and signaling.
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Affiliation(s)
- C M Hunker
- Department of Biological Sciences, Florida International University, College of Arts and Sciences, 11200 S.W. 8th Street, Bldg. OE, Room 167, Miami, FL 33199, USA
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Wilson C, Hargreaves M, Howlett KF. Exercise does not alter subcellular localization, but increases phosphorylation of insulin-signaling proteins in human skeletal muscle. Am J Physiol Endocrinol Metab 2006; 290:E341-6. [PMID: 16188907 DOI: 10.1152/ajpendo.00314.2005] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The subcellular localization of insulin signaling proteins is altered by various stimuli such as insulin, insulin-like growth factor I, and oxidative stress and is thought to be an important mechanism that can influence intracellular signal transduction and cellular function. This study examined the possibility that exercise may also alter the subcellular localization of insulin signaling proteins in human skeletal muscle. Nine untrained males performed 60 min of cycling exercise (approximately 67% peak pulmonary O2 uptake). Muscle biopsies were sampled at rest, immediately after exercise, and 3 h postexercise. Muscle was fractionated by centrifugation into the following crude fractions: cytosolic, nuclear, and a high-speed pellet containing membrane and cytoskeletal components. Fractions were analyzed for protein content of insulin receptor, insulin receptor substrate (IRS)-1 and -2, p85 subunit of phosphatidylinositol 3-kinase, Akt, and glycogen synthase kinase-3 (GSK-3). There was no significant change in the protein content of the insulin signaling proteins in any of the crude fractions after exercise or 3 h postexercise. Exercise had no significant effect on the phosphorylation of IRS-1 Tyr612 in any of the fractions. In contrast, exercise increased (P < 0.05) the phosphorylation of Akt Ser473 and GSK-3alpha/beta Ser9/21 in the cytosolic fraction only. In conclusion, exercise can increase phosphorylation of downstream insulin signaling proteins specifically in the cytosolic fraction but does not result in changes in the subcellular localization of insulin signaling proteins in human skeletal muscle. Change in the subcellular protein localization is therefore an unlikely mechanism to influence signal transduction pathways and cellular function in skeletal muscle after exercise.
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Affiliation(s)
- Chris Wilson
- Center for Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, Victoria, Australia
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35
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Thomas EC, Zhe Y, Molero JC, Schmitz-Peiffer C, Ramm G, James DE, Whitehead JP. The subcellular fractionation properties and function of insulin receptor substrate-1 (IRS-1) are independent of cytoskeletal integrity. Int J Biochem Cell Biol 2006; 38:1686-99. [PMID: 16702017 DOI: 10.1016/j.biocel.2006.03.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2006] [Revised: 03/15/2006] [Accepted: 03/20/2006] [Indexed: 10/24/2022]
Abstract
Efficient insulin action requires spatial and temporal coordination of signaling cascades. The prototypical insulin receptor substrate, IRS-1 plays a central role in insulin signaling. By subcellular fractionation IRS-1 is enriched in a particulate fraction, termed the high speed pellet (HSP), and its redistribution from this fraction is associated with signal attenuation and insulin resistance. Anecdotal evidence suggests the cytoskeleton may underpin the localization of IRS-1 to the HSP. In the present study we have taken a systematic approach to examine whether the cytoskeleton contributes to the subcellular fractionation properties and function of IRS-1. By standard microscopy or immunoprecipitation we were unable to detect evidence to support a specific interaction between IRS-1 and the major cytoskeletal components actin (microfilaments), vimentin (intermediate filaments), and tubulin (microtubules) in 3T3-L1 adipocytes or in CHO.IR.IRS-1 cells. Pharmacological disruption of microfilaments and microtubules, individually or in combination, was without effect on the subcellular distribution of IRS-1 or insulin-stimulated tyrosine phosphorylation in either cell type. Phosphorylation of Akt was modestly reduced (20-35%) in 3T3-L1 adipocytes but not in CHO.IR.IRS-1 cells. In cells lacking intermediate filaments (Vim(-/-)) IRS-1 expression, distribution and insulin-stimulated phosphorylation appeared normal. Even after depolymerisation of microfilaments and microtubules, insulin-stimulated phosphorylation of IRS-1 and Akt were maintained in Vim(-/-) cells. Taken together these data indicate that the characteristic subcellular fractionation properties and function of IRS-1 are unlikely to be mediated by cytoskeletal networks and that proximal insulin signaling does not require an intact cytoskeleton.
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Affiliation(s)
- Elaine C Thomas
- Centre for Diabetes and Endocrine Research, Princess Alexandra Hospital, University of Queensland, Brisbane, Qld 4102, Australia
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36
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Kim S, Pak Y. Caveolin-2 regulation of the cell cycle in response to insulin in Hirc-B fibroblast cells. Biochem Biophys Res Commun 2005; 330:88-96. [PMID: 15781236 DOI: 10.1016/j.bbrc.2005.02.130] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2005] [Indexed: 11/26/2022]
Abstract
The regulatory function of caveolin-2 in cell cycle regulation by insulin was investigated in human insulin receptor-overexpressed rat 1 fibroblast (Hirc-B) cells. Insulin increased induction of the caveolin-2 gene in a time-dependent manner. Direct interaction between ERK and caveolin-2 was confirmed by immunoprecipitation and phosphorylated ERK increased the specific interaction in response to insulin. That insulin induced their nuclear co-localization over time was demonstrated by immunofluorescence microscopy. Insulin increased the S phase in the cell cycle by 6-fold. When recombinant caveolin-1 was transiently expressed, a decrease in the S phase was detected by flow-cytometry. The results indicate that the up-regulation of caveolin-2 in response to insulin activates the downstream signal cascades in the cell cycle, chiefly the increased phosphorylation of ERK, the nuclear translocation of phosphorylated ERK, and the subsequent activation of G0/G1 to S phase transition of the cell cycle. The results also suggest that DNA synthesis and the activation of the cell cycle by insulin are achieved concomitantly with an increase in the interaction between caveolin-2 and phosphorylated ERK, and the nuclear translocation of that complex. Taken together, we conclude that caveolin-2 positively regulates the insulin-induced cell cycle through activation of and direct interaction with ERK in Hirc-B cells.
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Affiliation(s)
- Sangmin Kim
- Department of Biochemistry, Division of Life Science, College of Natural Sciences, Graduate School of Applied Life Science, Gyeongsang National University, Jinju 660-701, Republic of Korea
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Yang X, Palanichamy K, Ontko AC, Rao MNA, Fang CX, Ren J, Sreejayan N. A newly synthetic chromium complex - chromium(phenylalanine)3improves insulin responsiveness and reduces whole body glucose tolerance. FEBS Lett 2005; 579:1458-64. [PMID: 15733857 DOI: 10.1016/j.febslet.2005.01.049] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2004] [Revised: 01/20/2005] [Accepted: 01/25/2005] [Indexed: 10/25/2022]
Abstract
Low-molecular-weight organic chromium complexes such as chromium picolinate are often used as dietary supplements to improve insulin sensitivity and to correct dyslipidemia. However, toxicity associated with such chromium compounds has compromised their therapeutic value. The aim of this study was to evaluate the impact of a newly synthesized complex of chromium with phenylalanine, Cr(pa)3 on insulin-signaling and glucose tolerance. Cr(pa)3 was synthesized by chelating chromium(III) with D-phenylalanine ligand in aqueous solution. In mouse 3T3-adipocytes, Cr(pa)3 augmented insulin-stimulated glucose-uptake as assessed by a radioactive-glucose uptake assay. At the molecular level, Cr(pa)3 enhanced insulin-stimulated phosphorylation of Akt in a time- and concentration-dependent manner without altering the phosphorylation of insulin receptor. Oral treatment with Cr(pa)3 (150 microg/kg/d, for six weeks) in ob/ob+/+ obese mice significantly alleviated glucose tolerance compared with untreated obese mice. Unlike chromium picolinate, Cr(pa)3 does not cleave DNA under physiological reducing conditions. Collectively, these data suggest that Cr(pa)3 may represent a novel, less-toxic chromium supplement with potential therapeutic value to improve insulin sensitivity and glycemic control in type II diabetes.
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Affiliation(s)
- Xiaoping Yang
- Division of Pharmaceutical Sciences, School of Pharmacy, University of Wyoming, Laramie, WY 82071, USA
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38
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Claeys I, Poels J, Simonet G, Franssens V, Van Loy T, Van Hiel MB, Breugelmans B, Vanden Broeck J. Insect Neuropeptide and Peptide Hormone Receptors: Current Knowledge and Future Directions. VITAMINS & HORMONES 2005; 73:217-82. [PMID: 16399412 DOI: 10.1016/s0083-6729(05)73007-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Peptides form a very versatile class of extracellular messenger molecules that function as chemical communication signals between the cells of an organism. Molecular diversity is created at different levels of the peptide synthesis scheme. Peptide messengers exert their biological functions via specific signal-transducing membrane receptors. The evolutionary origin of several peptide precursor and receptor gene families precedes the divergence of the important animal Phyla. In this chapter, current knowledge is reviewed with respect to the analysis of peptide receptors from insects, incorporating many recent data that result from the sequencing of different insect genomes. Therefore, detailed information is provided on six different peptide receptor families belonging to two distinct receptor categories (i.e., the heptahelical and the single transmembrane receptors). In addition, the remaining problems, the emerging concepts, and the future prospects in this area of research are discussed.
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MESH Headings
- Animals
- Drosophila/genetics
- Drosophila/physiology
- Drosophila Proteins/genetics
- Drosophila Proteins/physiology
- Forecasting
- Frizzled Receptors/genetics
- Frizzled Receptors/physiology
- Insecta/genetics
- Insecta/physiology
- Invertebrate Hormones/genetics
- Invertebrate Hormones/physiology
- Receptor Protein-Tyrosine Kinases/physiology
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/physiology
- Receptors, Gastrointestinal Hormone/genetics
- Receptors, Gastrointestinal Hormone/physiology
- Receptors, Guanylate Cyclase-Coupled/genetics
- Receptors, Guanylate Cyclase-Coupled/physiology
- Receptors, Invertebrate Peptide/genetics
- Receptors, Invertebrate Peptide/physiology
- Receptors, Peptide/genetics
- Receptors, Peptide/physiology
- Receptors, Tachykinin/genetics
- Receptors, Tachykinin/physiology
- Receptors, Transforming Growth Factor beta/physiology
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Affiliation(s)
- Ilse Claeys
- Laboratory for Developmental Physiology, Genomics and Proteomics Department of Animal Physiology and Neurobiology, Zoological Institute K.U.Leuven, Naamsestraat 59, B-3000 Leuven, Belgium
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Park SY, Choi GH, Choi HI, Ryu J, Jung CY, Lee W. Depletion of mitochondrial DNA causes impaired glucose utilization and insulin resistance in L6 GLUT4myc myocytes. J Biol Chem 2004; 280:9855-64. [PMID: 15764607 DOI: 10.1074/jbc.m409399200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Mitochondrial dysfunction contributes to a number of human diseases, such as hyperlipidemia, obesity, and diabetes. The mutation and reduction of mitochondrial DNA (mtDNA) have been suggested as factors in the pathogenesis of diabetes. To elucidate the association of cellular mtDNA content and insulin resistance, we produced L6 GLUT4myc myocytes depleted of mtDNA by long term treatment with ethidium bromide. L6 GLUT4myc cells cultured with 0.2 mug/ml ethidium bromide (termed depleted cells) revealed a marked decrease in cellular mtDNA and ATP content, concomitant with a lack of mRNAs encoded by mtDNA. Interestingly, the mtDNA-depleted cells showed a drastic decrease in basal and insulin-stimulated glucose uptake, indicating that L6 GLUT4myc cells develop impaired glucose utilization and insulin resistance. The repletion of mtDNA normalized basal and insulin-stimulated glucose uptake. The mRNA level and expression of insulin receptor substrate (IRS)-1 associated with insulin signaling were decreased by 76 and 90% in the depleted cells, respectively. The plasma membrane (PM) GLUT4 in the basal state was decreased, and the insulin-stimulated GLUT4 translocation to the PM was drastically reduced by mtDNA depletion. Moreover, insulin-stimulated phosphorylation of IRS-1 and Akt2/protein kinase B were drastically reduced in the depleted cells. Those changes returned to control levels after mtDNA repletion. Taken together, our data suggest that PM GLUT4 content and insulin signal pathway intermediates are modulated by the alteration of cellular mtDNA content, and the reductions in the expression of IRS-1 and insulin-stimulated phosphorylation of IRS-1 and Akt2/protein kinase B are associated with insulin resistance in the mtDNA-depleted L6 GLUT4myc myocytes.
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Affiliation(s)
- Seung Y Park
- Department of Biochemistry, College of Medicine, Dongguk University, Kyungju 780-714, Korea
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40
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Danielsson A, Ost A, Lystedt E, Kjolhede P, Gustavsson J, Nystrom FH, Strålfors P. Insulin resistance in human adipocytes occurs downstream of IRS1 after surgical cell isolation but at the level of phosphorylation of IRS1 in type 2 diabetes. FEBS J 2004; 272:141-51. [PMID: 15634339 DOI: 10.1111/j.1432-1033.2004.04396.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Insulin resistance is a cardinal feature of type 2 diabetes and also a consequence of trauma such as surgery. Directly after surgery and cell isolation, adipocytes were insulin resistant, but this was reversed after overnight incubation in 10% CO(2) at 37 degrees C. Tyrosine phosphorylation of the insulin receptor and insulin receptor substrate (IRS)1 was insulin sensitive, but protein kinase B (PKB) and downstream metabolic effects exhibited insulin resistance that was reversed by overnight incubation. MAP-kinases ERK1/2 and p38 were strongly phosphorylated after surgery, but was dephosphorylated during reversal of insulin resistance. Phosphorylation of MAP-kinase was not caused by collagenase treatment during cell isolation and was present also in tissue pieces that were not subjected to cell isolation procedures. The insulin resistance directly after surgery and cell isolation was different from insulin resistance of type 2 diabetes; adipocytes from patients with type 2 diabetes remained insulin resistant after overnight incubation. IRS1, PKB, and downstream metabolic effects, but not insulin-stimulated tyrosine phosphorylation of insulin receptor, exhibited insulin resistance. These findings suggest a new approach in the study of surgery-induced insulin resistance and indicate that human adipocytes should recover after surgical procedures for analysis of insulin signalling. Moreover, we pinpoint the signalling dysregulation in type 2 diabetes to be the insulin-stimulated phosphorylation of IRS1 in human adipocytes.
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Affiliation(s)
- Anna Danielsson
- Department of Cell Biology and Diabetes Research Centre, University of Linköping, Sweden
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41
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Ma Y, Toth B, Keeton AB, Holland LT, Chaudry IH, Messina JL. Mechanisms of hemorrhage-induced hepatic insulin resistance: role of tumor necrosis factor-alpha. Endocrinology 2004; 145:5168-76. [PMID: 15297437 DOI: 10.1210/en.2004-0524] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Hemorrhage, sepsis, burn injury, surgical trauma and critical illness all induce insulin resistance. Recently we found that trauma and hemorrhage acutely induced hepatic insulin resistance in the rat. However, the mechanisms of this hemorrhage-induced acute hepatic insulin resistance are unknown. Here we report on the mechanisms of this hepatic insulin resistance. Protein levels and phosphorylation of the insulin receptor and insulin receptor substrate-1/2 (IRS-1/2) were measured, as was the association between IRS-1/2 and phosphatidylinositol 3-kinase (PI3K). Also examined were the hepatic expression of TNFalpha and TNFalpha-induced serine phosphorylation of IRS-1. Insulin receptor and IRS-1/2 protein levels and insulin-induced tyrosine phosphorylation of the insulin receptor were unaltered. In contrast, insulin-induced tyrosine phosphorylation of IRS-1/2 and association between IRS-1/2 and PI3K were dramatically reduced after hemorrhage. Hepatic levels of TNFalpha mRNA and protein were increased as was phosphorylation of IRS-1 serine 307 after hemorrhage. Our data provide the first evidence that compromised IRS-1/2 tyrosine phosphorylation and their association with PI3K contribute to hemorrhage-induced acute hepatic insulin resistance. Increased local TNFalpha may play a role in inducing this hepatic insulin resistance after trauma and hemorrhage.
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Affiliation(s)
- Yuchen Ma
- Department of Pathology, Division of Molecular and Cellular Pathology, Volker Hall, G019, 1670 University Boulevard, University of Alabama at Birmingham, Birmingham, Alabama 35294-0019, USA
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Korićanac G, Vulović M, Radivojsa S, Zakula Z, Ribarac-Stepić N. Age-related changes of insulin receptors, plasma insulin and glucose level. Biogerontology 2004; 5:345-53. [PMID: 15547322 DOI: 10.1007/s10522-004-2576-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The effects of aging on hepatic and erythrocyte insulin receptors have been investigated in 6, 12, 18 and 21-months-old compare to 3-months-old rats. Plasma insulin was elevated in 6, 12 and 18-months-old rats. Specific binding of insulin in liver was increased at the age of 8 months and accompanied with increase in concentration of low affinity binding sites, while specific binding to erythrocytes as well as concentration of both classes of binding sites was increased in 6-months-old rats. The protein and mRNA content of hepatic receptor were decreased only in the oldest animals. Plasma glucose was elevated starting from 12-months-old rats, while, after decrease in 6-months-old animals, citrulline was raised in the oldest group. The results demonstrating that specific binding of insulin in liver and erythrocytes and the concentration of binding sites in both tissues were not decreased during aging, as well as the absence of changes in affinity of insulin binding sites do not point out to occurrence of insulin resistance. However, the increase in insulinemia in the middle of lifespan, elevated plasma glucose and citrulline as well as decrease of hepatic receptor protein and mRNA content in the oldest animals indicate some age-related changes in insulin signaling.
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Affiliation(s)
- Goran Korićanac
- Department for Molecular Biology and Endocrinology, Vinca Institute of Nuclear Sciences, PO Box 522, 11001 Belgrade, Serbia and Montenegro.
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Martens N, Wery M, Wang P, Braet F, Gertler A, Hooghe R, Vandenhaute J, Hooghe-Peters EL. The suppressor of cytokine signaling (SOCS)-7 interacts with the actin cytoskeleton through vinexin. Exp Cell Res 2004; 298:239-48. [PMID: 15242778 DOI: 10.1016/j.yexcr.2004.04.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Revised: 03/16/2004] [Indexed: 10/26/2022]
Abstract
To understand the function of the suppressor of cytokine signaling (SOCS)-7, we have looked for proteins interacting with SOCS-7 in a stringent yeast two-hybrid screen of a human leukocyte cDNA-library. We identified the cytoskeletal molecule vinexin as a partner interacting with SOCS-7. Tests with deletion mutants of SOCS-7 demonstrated that a central region of the molecule containing several proline-rich regions, N-terminal to the SH2 domain, was responsible for the binding to vinexin. It is thus likely that one of the SH3 domains of vinexin interacts with a poly-proline region of SOCS-7. The interaction with vinexin was confirmed biochemically as vinexin-alpha was co-precipitated with SOCS-7. Confocal laser-scanning microscopy in HEK293T, MCF-7, and 3T3-L1 cells showed that part of the transfected SOCS-7-green fluorescent protein (GFP) molecules merged with vinexin and with actin. Taken together, our data indicate that SOCS-7 interacts with vinexin and the actin cytoskeleton.
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Affiliation(s)
- Nele Martens
- Neuroendocrine Immunology Group, Pharmacology Department, Medical School, Free University of Brussels (VUB), 1090, Belgium.
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44
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Abstract
This article provides an overview of the pathogenesis of type 2 diabetes mellitus. Discussion begins by describing normal glucose homeostasis and ingestion of a typical meal and then discusses glucose homeostasis in diabetes. Topics covered include insulin secretion in type 2 diabetes mellitus and insulin resistance, the site of insulin resistance, the interaction between insulin sensitivity and secretion, the role of adipocytes in the pathogenesis of type 2 diabetes, cellular mechanisms of insulin resistance including glucose transport and phosphorylation, glycogen and synthesis,glucose and oxidation, glycolysis, and insulin signaling.
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Affiliation(s)
- Ralph A DeFronzo
- Diabetes Division, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
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45
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Sun L, Liu L, Yang XJ, Wu Z. Akt binds prohibitin 2 and relieves its repression of MyoD and muscle differentiation. J Cell Sci 2004; 117:3021-9. [PMID: 15173318 DOI: 10.1242/jcs.01142] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In a yeast two-hybrid screen using the full-length Akt as bait, we found that prohibitin 2 (PHB2) specifically interacts with Akt. The C terminus of Akt (amino acids 413-480) and a central region of PHB2 (amino acids 120-232) are responsible for their mutual interaction. PHB2 acts as a transcriptional repressor in cells. PHB2 interacts with both MyoD and MEF2, and represses both MyoD- and MEF2-dependent gene transcription. Furthermore, binding of PHB2 to both MyoD and MEF2 significantly decreases upon myogenic differentiation. When stably expressed in C2C12 myogenic cells, PHB2 inhibits myogenin induction and phenotypic muscle differentiation. PHB2 was found to specifically recruit histone deacetylase 1, which is probably responsible for its repressive activity. Co-expression of Akt can partially reduce PHB2 binding to MyoD and relieve the repressive effect of PHB2 on myogenic reporters, which could be one of the mechanisms underlying Akt-mediated MyoD activation and accelerated muscle differentiation.
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Affiliation(s)
- Luguo Sun
- Department of Biochemistry, Hong Kong University of Science and Technology, Hong Kong, China
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46
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Abstract
BACKGROUND Leukocyte dysfunction contributes to the pathogenesis of diabetic vascular complications. Neutrophils adhere to the endothelium through the beta(2)integrin CD11b/CD18. In Type 2 diabetes, neutrophil surface CD11b expression is increased and is associated with impaired actin polymerization. This study aimed to determine whether increasing neutrophil actin polymerization could correct the defect in CD11b exposure. DESIGN Neutrophil actin polymerization was stimulated with the tyrosine phosphatase inhibitor phenylarsine oxide (PAO), and cytoskeletal phosphotyrosine was monitored by immunoblotting Triton X-100 insoluble fractions of cells. Neutrophil F-actin was measured with phalloidin-FITC staining, and surface CD11b expression was determined with anti-CD11b-PE before analysis with flow cytometry. RESULTS Phenylarsine oxide caused an increase in phosphotyrosine in neutrophils from both patients with Type 2 diabetes (DM) and controls (NC) (-fold increase: NC, 1.43 +/- 0.16; DM, 1.46 +/- 0.10). The response to PAO in terms of phalloidin-binding was impaired in neutrophils from patients [phalloidin-FITC MFI area under the curve, NC 200 +/- 5 (x 10(3)), DM 124 +/- 9 (x 10(3)), P < 0.0001]. Phenylarsine oxide at concentrations < 10 micro mol L(-1) also caused loss of CD11b from neutrophil surfaces that was impaired in samples from patients [CD11b sites area under the curve NC 90 +/- 6 (x 10(3)), DM 121 +/- 9 (x 10(3)), P < 0.002]. However, in neutrophils from patients, incubation with PAO at a concentration of > 10 micro mol L(-1) caused a significant increase in intracellular F-actin and CD11b down-regulation equivalent to that observed in controls. CONCLUSION In Type 2 diabetes, impaired neutrophil actin polymerization even in response to increasing cytoskeletal phophotyrosine suggests a downstream defect. Furthermore, increasing actin polymerization, above a minimum threshold level, corrects the defect in integrin exposure. Correction of the actin polymerization defect in Type 2 diabetes could improve the prognosis of diabetic vascular complications.
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Affiliation(s)
- A Advani
- Department of Medicine, University of Newcastle Upon Tyne, Newcastle Upon Tyne, UK.
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47
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Bedirian A, Baldwin C, Abe JI, Takano T, Lemay S. Pleckstrin Homology and Phosphotyrosine-binding Domain-dependent Membrane Association and Tyrosine Phosphorylation of Dok-4, an Inhibitory Adapter Molecule Expressed in Epithelial Cells. J Biol Chem 2004; 279:19335-49. [PMID: 14963042 DOI: 10.1074/jbc.m310689200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dok-like adapter molecules represent an expanding family of pleckstrin homology (PH) and phosphotyrosine-binding (PTB) domain-containing tyrosine kinase substrates with negative regulatory functions in hematopoietic cell signaling. In a search for nonhematopoietic counterparts to Dok molecules, we identified and characterized Dok-4, a recently cloned member of the family. dok-4 mRNA was strongly expressed in nonhematopoietic organs, particularly the intestine, kidney, and lung, whereas both mRNA and protein were expressed at high levels in cells of epithelial origin. In Caco-2 human colon cancer cells, endogenous Dok-4 underwent tyrosine phosphorylation in response to pervanadate stimulation. In transfected COS cells, Dok-4 was a substrate for the cytosolic tyrosine kinases Src and Fyn as well as for Jak2. Dok-4 could also be phosphorylated by the receptor tyrosine kinase Ret but not by platelet-derived growth factor receptor-beta or IGF-IR. In both mammalian cells and yeast, Dok-4 was constitutively localized at the membrane in a manner that required both its PH and PTB domains. The PH and PTB domains of Dok-4 were also required for tyrosine phosphorylation of Dok-4 by Fyn and Ret. Finally, wild type Dok-4 strongly inhibited activation of Elk-1 induced by either Ret or Fyn. The attenuation of this inhibitory effect by deletion of the PH domain and its restoration by the addition of a myristoylation signal suggested an important role for constitutive membrane localization of Dok-4. In summary, Dok-4 is a constitutively membrane-localized adapter molecule that may function as an inhibitor of tyrosine kinase signaling in epithelial cells.
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Affiliation(s)
- Arda Bedirian
- Department of Medicine, Division of Nephrology, McGill University Health Centre, Montreal, Quebec H3A 2B4, Canada
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48
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Rajala RVS, Anderson RE. Light regulation of the insulin receptor in the retina. Mol Neurobiol 2004; 28:123-38. [PMID: 14576451 DOI: 10.1385/mn:28:2:123] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2003] [Accepted: 02/17/2003] [Indexed: 12/19/2022]
Abstract
The peptide hormone insulin binds its cognate cell-surface receptors to activate a coordinated biochemical-signaling network and to induce intracellular events. The retina is an integral part of the central nervous system and is known to contain insulin receptors, although their function is unknown. This article, describes recent studies that link the photobleaching of rhodopsin to tyrosine phosphorylation of the insulin receptor and subsequent activation of phosphoinositide 3- kinase (PI3K). We recently found a light-dependent increase in tyrosine phosphorylation of the insulin receptor-beta-subunit (IR beta) and an increase in PI3K enzyme activity in isolated rod outer segments (ROS) and in anti-phosphotyrosine (PY) and anti-IR beta immunoprecipitates of retinal homogenates. The light effect, which was localized to photoreceptor neurons, is independent of insulin secretion. Our results suggest that light induces tyrosine phosphorylation of IR beta in outer-segment membranes, which leads to the binding of p85 through its N-terminal SH2 domain and the generation of PI-3,4,5-P3. We suggest that the physiological role of this process may be to provide neuroprotection of the retina against light damage by activating proteins that protect against stress-induced apoptosis. The studies linking PI3K activation through tyrosine phosphorylation of IR beta now provide physiological relevance for the presence of these receptors in the retina.
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Affiliation(s)
- Raju V S Rajala
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, 73104, USA.
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49
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Abstract
Hepatic lipid accumulation may be a result of one or several of the following factors: increased delivery of adipose tissue or dietary fatty acids to the liver, increased de novo synthesis of fatty acids in the liver, decreased rate of hepatic fatty-acid oxidation, or decreased rate in the exit of fatty acids from the liver in the form of triglycerides. Delivery of fatty acids to the liver appears to be the most potent mechanism for hepatic lipid accumulation. Hepatic lipid accumulation is linked to the development of hepatic insulin resistance, which is demonstrated by the impaired suppression of hepatic glucose output by insulin. Current evidence suggests that defects associated with the molecular mechanisms responsible for the propagation of the insulin signal in the liver cells are responsible for the impaired insulin effect and that these defects can develop secondary to lipid accumulation in the liver. Hepatic lipid accumulation appears to affect the activity of phosphatidylinositol 3-kinase, which has a central role in mediating the insulin action in hepatocytes. Generally, exercise has been shown to enhance the insulin action in the liver. Although an exercise-related mechanistic link between attenuation in hepatic lipid accumulation and enhancement in insulin action in the liver has not been described yet, the benefits of exercise on hepatic insulin action may relate to the potential effects of exercise on regulating/preventing hepatic lipid accumulation. However, direct effects of exercise on insulin action in the liver, independent of any effects on hepatic lipid metabolism, cannot currently be excluded. Further research is needed to evaluate the relative importance of exercise in the treatment of hepatic insulin resistance, specifically as it relates to lipid accumulation in the liver.
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Affiliation(s)
- Christos S Katsanos
- Department of Surgery, The University of Texas Medical Branch, Galveston, Texas, USA.
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50
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Bolander FF. Phosphorylation and Other Nontranscriptional Effects of Hormones. Mol Endocrinol 2004. [DOI: 10.1016/b978-012111232-5/50012-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022] Open
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