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Zhang Y, Liu Y, Shi Y, Bai C, Wang T, Ruan F, Hu C. Upregulation of MMPs in placentas of patients with gestational diabetes mellitus: Involvement of the PI3K/Akt pathway. Heliyon 2024; 10:e32518. [PMID: 39021921 PMCID: PMC11252657 DOI: 10.1016/j.heliyon.2024.e32518] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 06/04/2024] [Accepted: 06/05/2024] [Indexed: 07/20/2024] Open
Abstract
In recent years, there has been a notable rise in the incidence of pregnancies complicated by gestational diabetes mellitus (GDM), characterized by glucose intolerance first identified during pregnancy. Analysis of placental tissue has revealed that placentas from women with GDM tend to be larger and heavier compared to control placentas, indicating potential changes in trophoblast proliferation, differentiation, and apoptosis. In this study, transcriptome sequencing was conducted on placentas obtained from both normal pregnancies and pregnancies with GDM to investigate the molecular mechanisms underlying this condition. The original sequencing data were subjected to sequencing analysis, resulting in the identification of 935 upregulated genes and 256 downregulated genes. The KEGG and GO analysis techniques on differential genes uncovered evidence suggesting that the phosphoinositide 3-kinase (PI3K)/Akt signaling pathway may contribute to the pathogenesis of GDM. Subsequent analysis indicated that the expression levels of matrix metalloproteinases (MMP) 11, MMP12, MMP14, and MMP15, which are regulated by the PI3K/Akt pathway, were upregulated in the placentas of patients with GDM when compared to those of individuals with normal placental function. Additionally, our investigation into alternative splicing patterns revealed an increase in exon skipping alternative splicing of CSF3R in the placenta of patients with GDM compared to that in the control group. The CSF3R-PI3K-MMP pathway is speculated to regulate the pathogenesis of GDM.
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Affiliation(s)
- Yanan Zhang
- Department of Obstetrics, Affiliated Hospital of Jining Medical University, Jining, Shandong Province, 272029, PR China
| | - Yufen Liu
- Department of Obstetrics, Affiliated Hospital of Jining Medical University, Jining, Shandong Province, 272029, PR China
| | - Yanyan Shi
- Department of Pediatric Surgery, Affiliated Hospital of Jining Medical University, Jining, Shandong Province, 272029, PR China
| | - Chunyu Bai
- Precision Medicine Laboratory for Chronic Non-communicable Diseases of Shandong Province, Institute of Precision Medicine, Jining Medical University, Jining, Shandong, 272067, PR China
| | - Ting Wang
- Department of Pathology, Affiliated Hospital of Jining Medical University, Jining, Shandong Province, 272029, PR China
| | - Fang Ruan
- Department of Obstetrics, Affiliated Hospital of Jining Medical University, Jining, Shandong Province, 272029, PR China
| | - Chuanbing Hu
- Department of Pediatric Surgery, Affiliated Hospital of Jining Medical University, Jining, Shandong Province, 272029, PR China
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Tomlinson PR, Knox R, Perisic O, Su HC, Brierley GV, Williams RL, Semple RK. Paradoxical dominant negative activity of an immunodeficiency-associated activating PIK3R1 variant. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.02.565250. [PMID: 38077044 PMCID: PMC10705566 DOI: 10.1101/2023.11.02.565250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
PIK3R1 encodes three regulatory subunits of class IA phosphoinositide 3-kinase (PI3K), each associating with any of three catalytic subunits, namely p110α, p110β or p110δ. Constitutional PIK3R1 mutations cause diseases with a genotype-phenotype relationship not yet fully explained: heterozygous loss-of-function mutations cause SHORT syndrome, featuring insulin resistance and short stature attributed to reduced p110α function, while heterozygous activating mutations cause immunodeficiency, attributed to p110δ activation and known as APDS2. Surprisingly, APDS2 patients do not show features of p110α hyperactivation, but do commonly have short stature or SHORT syndrome, suggesting p110α hypofunction. We sought to investigate this. In dermal fibroblasts from an APDS2 patient, we found no increased PI3K signalling, with p110δ expression markedly reduced. In preadipocytes, the APDS2 variant was potently dominant negative, associating with Irs1 and Irs2 but failing to heterodimerise with p110α. This attenuation of p110α signalling by a p110δ-activating PIK3R1 variant potentially explains co-incidence of gain-of-function and loss-of-function PIK3R1 phenotypes.
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Affiliation(s)
- Patsy R. Tomlinson
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, UK
- MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Rachel Knox
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, UK
- MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Olga Perisic
- MRC Laboratory of Molecular Biology, Cambridge, UK
| | - Helen C. Su
- Laboratory of Clinical Immunology & Microbiology, Intramural Research Program, National Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, MD, USA
| | - Gemma V. Brierley
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
- The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, UK
- MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | | | - Robert K. Semple
- MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
- Centre for Cardiovascular Science, University of Edinburgh, Edinburgh, UK
- MRC Human Genetics Unit, Institute of Genetics and Cancer, University of Edinburgh, Edinburgh, UK
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Fan Z, Wang L, Li C, Wu D, Li J, Zhang H, Xiong S, Miao L, Ge X, Li Z. Integration of microRNA and mRNA analyses depicts the potential roles of Momordica charantia saponin administration in insulin resistance of juvenile common carp ( Cyprinus carpio) fed with a high-starch diet. Front Mol Biosci 2023; 10:1054949. [PMID: 37091861 PMCID: PMC10113649 DOI: 10.3389/fmolb.2023.1054949] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 03/21/2023] [Indexed: 04/25/2023] Open
Abstract
Background: The regulation of target gene mRNA mediated by microRNA may play an important role in glucose metabolism in fish. Previous research findings of our research group revealed that Momordica charantia saponin (MS) administration in a high-starch diet could improve insulin resistance of common carp through renovating insulin signaling pathways, whose fundamental mechanisms have remained unknown by far. To reveal this potential mechanism, we aimed to investigate the difference in miRNA and mRNA expression profiles between common carp fed with high-starch diets containing MS (HS_MS1 and HS_MS2) and common carp fed with high-starch (HS) diets. Results: Through miRNA deep-sequencing, 10 significantly differentially expressed miRNAs in HC and HS_MS1, including one upregulated and nine downregulated miRNAs, were identified, whereas 10 significantly differentially expressed miRNAs in HC and HS_MS2, including four upregulated and six downregulated miRNAs, were identified. These miRNAs may not only be involved in the regulation of insulin signaling pathways and insulin resistance in common carp but also be the markers for liver insulin resistance in MS therapy for the remission of insulin resistance. This study identified 10 potential known miRNAs, namely, ccr-miR-10b, ccr-miR-122, ccr-miR-143, ccr-miR-146a, ccr-miR-155, ccr-miR-16c, ccr-miR-200a, ccr-miR-29a, ccr-miR-34, and ccr-miR-375, as candidates participating in modulating the liver insulin resistance. According to the biopathway enrichment analysis of the 252 target genes using the KEGG classical biopathway database, the relative expression levels of gsk3bb, pik3r1, and pik3r3b were analyzed using RNA-seq. Compared to the HC group, a significant decrease in the relative expression levels of pik3r1 and pik3r3b was observed in HS_MS1 and HS_MS2 groups (p < 0.05). This study raised a presumption of the presence of ccr-miR-29a targeting pik3r1 or ccr-miR-143 targeting pik3r3 playing likely roles in Momordica charantia saponins remitting the liver insulin resistance. Conclusion: The findings will further deepen the understanding of the carbohydrate metabolism of common carp and provide an important scientific basis for the application of Momordica saponins as functional nutrients to alleviate insulin resistance of fish in fish culture.
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Affiliation(s)
- Ze Fan
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China
| | - Liansheng Wang
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China
- *Correspondence: Liansheng Wang, ; Haitao Zhang,
| | - Chenhui Li
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China
| | - Di Wu
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China
| | - Jinnan Li
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China
| | - Haitao Zhang
- Key Laboratory of Aquatic, Livestock and Poultry Feed Science and Technology in South China, Ministry of Agriculture and Rural Affairs, Guangdong Evergreen Feed Industry Co., Ltd., Zhanjiang, China
- *Correspondence: Liansheng Wang, ; Haitao Zhang,
| | - Siwei Xiong
- Key Laboratory of Aquatic Animal Diseases and Immune Technology of Heilongjiang Province, Heilongjiang River Fisheries Research Institute, Chinese Academy of Fishery Sciences, Harbin, China
- Tianjin Agricultural University, Tianjin, China
| | - Linghong Miao
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Xianping Ge
- Key Laboratory of Freshwater Fisheries and Germplasm Resources Utilization, Ministry of Agriculture and Rural Affairs, Freshwater Fisheries Research Center, Chinese Academy of Fishery Sciences, Wuxi, China
| | - Zhengwei Li
- Heilongjiang Aquatic Animal Resource Conservation Center, Heilongjiang, China
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Differential effects of single fatty acids and fatty acid mixtures on the phosphoinositide 3-kinase/Akt/eNOS pathway in endothelial cells. Eur J Nutr 2022; 61:2463-2473. [PMID: 35157107 PMCID: PMC9279250 DOI: 10.1007/s00394-022-02821-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Accepted: 01/25/2022] [Indexed: 12/30/2022]
Abstract
SCOPE Dietary fat composition is an important modulator of vascular function. Non-esterified fatty acids (NEFA) enriched in saturated fatty acids (SFA) are thought to reduce vascular reactivity by attenuating insulin signalling via vasodilator pathways (phosphoinositide 3-kinase (PI3K)/Akt/endothelial nitric oxide synthase (eNOS)) and enhancing signalling via pro-inflammatory pathways. METHODS To examine the effects of fatty acids on these pathways, human aortic endothelial cells were incubated with single fatty acids, and mixtures of these fatty acids to mimic typical NEFA composition and concentrations achieved in our previous human study. RNA was extracted to determine gene expression using real-time RT-PCR and cell lysates prepared to assess protein phosphorylation by Western blotting. RESULTS Oleic acid (OA, 100 µM) was shown to down regulate expression of the insulin receptor, PTEN and a PI3K catalytic (p110β) and regulatory (p85α) subunit compared to palmitic, linoleic and stearic acids (P < 0.04), and promote greater eNOS phosphorylation at Ser1177. Both concentration and composition of the SFA and SFA plus n-3 polyunsaturated fatty acids (PUFA) mixtures had significant effects on genes involved in the PI3K/Akt pathway. Greater up-regulation was found with 800 than 400 µM concentration (respective of concentrations in insulin resistant and normal individuals), whereas greater down-regulation was evident with SFA plus n-3 PUFA than SFA mixture alone. CONCLUSION Our findings provide novel insights into the modulation of the PI3K/Akt/eNOS pathway by single fatty acids and fatty acid mixtures. In particular, OA appears to promote signalling via this pathway, with further work required to determine the primary molecular site(s) of action.
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Is type 2 diabetes an adiposity-based metabolic disease? From the origin of insulin resistance to the concept of dysfunctional adipose tissue. Eat Weight Disord 2021; 26:2429-2441. [PMID: 33555509 PMCID: PMC8602224 DOI: 10.1007/s40519-021-01109-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 01/12/2021] [Indexed: 12/13/2022] Open
Abstract
In the last decades of the past century, a remarkable amount of research efforts, money and hopes was generated to unveil the basis of insulin resistance that was believed to be the primary etiological factor in the development of type 2 diabetes. From the Reaven's insulin resistance syndrome to the DeFronzo's triumvirate (skeletal muscle, liver and beta-cell) and to Kahn's discovery (among many others) of insulin receptor downregulation and autophosphorylation, an enthusiastic age of metabolic in vivo and in vitro research took place, making the promise of a resolutory ending. However, from many published data (those of insulin receptoropathies and lipodystrophies, the genome-wide association studies results, the data on reversibility of type 2 diabetes after bariatric surgery or very-low-calorie diets, and many others) it appears that insulin resistance is not a primary defect but it develops secondarily to increased fat mass. In particular, it develops from a mismatch between the surplus caloric intake and the storage capacity of adipose tissue. On this basis, we propose to change the today's definition of type 2 diabetes in adiposity-based diabetes.Level of Evidence as a narrative review a vast array of studies have been included in the analysis, ranging from properly designed randomized controlled trials to case studies; however, the overall conclusion may be regarded as level IV.
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Class IA PI3K regulatory subunits: p110-independent roles and structures. Biochem Soc Trans 2021; 48:1397-1417. [PMID: 32677674 PMCID: PMC7458397 DOI: 10.1042/bst20190845] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/26/2020] [Accepted: 06/30/2020] [Indexed: 12/12/2022]
Abstract
The phosphatidylinositol 3-kinase (PI3K) pathway is a critical regulator of many cellular processes including cell survival, growth, proliferation and motility. Not surprisingly therefore, the PI3K pathway is one of the most frequently mutated pathways in human cancers. In addition to their canonical role as part of the PI3K holoenzyme, the class IA PI3K regulatory subunits undertake critical functions independent of PI3K. The PI3K regulatory subunits exist in excess over the p110 catalytic subunits and therefore free in the cell. p110-independent p85 is unstable and exists in a monomer-dimer equilibrium. Two conformations of dimeric p85 have been reported that are mediated by N-terminal and C-terminal protein domain interactions, respectively. The role of p110-independent p85 is under investigation and it has been found to perform critical adaptor functions, sequestering or influencing compartmentalisation of key signalling proteins. Free p85 has roles in glucose homeostasis, cellular stress pathways, receptor trafficking and cell migration. As a regulator of fundamental pathways, the amount of p110-independent p85 in the cell is critical. Factors that influence the monomer-dimer equilibrium of p110-independent p85 offer additional control over this system, disruption to which likely results in disease. Here we review the current knowledge of the structure and functions of p110-independent class IA PI3K regulatory subunits.
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7
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Chen TC, Kuo T, Dandan M, Lee RA, Chang M, Villivalam SD, Liao SC, Costello D, Shankaran M, Mohammed H, Kang S, Hellerstein MK, Wang JC. The role of striated muscle Pik3r1 in glucose and protein metabolism following chronic glucocorticoid exposure. J Biol Chem 2021; 296:100395. [PMID: 33567340 PMCID: PMC8010618 DOI: 10.1016/j.jbc.2021.100395] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 01/29/2021] [Accepted: 02/04/2021] [Indexed: 11/03/2022] Open
Abstract
Chronic glucocorticoid exposure causes insulin resistance and muscle atrophy in skeletal muscle. We previously identified phosphoinositide-3-kinase regulatory subunit 1 (Pik3r1) as a primary target gene of skeletal muscle glucocorticoid receptors involved in the glucocorticoid-mediated suppression of insulin action. However, the in vivo functions of Pik3r1 remain unclear. Here, we generated striated muscle-specific Pik3r1 knockout (MKO) mice and treated them with a dexamethasone (DEX), a synthetic glucocorticoid. Treating wildtype (WT) mice with DEX attenuated insulin activated Akt activity in liver, epididymal white adipose tissue, and gastrocnemius (GA) muscle. This DEX effect was diminished in GA muscle of MKO mice, therefore, resulting in improved glucose and insulin tolerance in DEX-treated MKO mice. Stable isotope labeling techniques revealed that in WT mice, DEX treatment decreased protein fractional synthesis rates in GA muscle. Furthermore, histology showed that in WT mice, DEX treatment reduced GA myotube diameters. In MKO mice, myotube diameters were smaller than in WT mice, and there were more fast oxidative fibers. Importantly, DEX failed to further reduce myotube diameters. Pik3r1 knockout also decreased basal protein synthesis rate (likely caused by lower 4E-BP1 phosphorylation at Thr37/Thr46) and curbed the ability of DEX to attenuate protein synthesis rate. Finally, the ability of DEX to inhibit eIF2α phosphorylation and insulin-induced 4E-BP1 phosphorylation was reduced in MKO mice. Taken together, these results demonstrate the role of Pik3r1 in glucocorticoid-mediated effects on glucose and protein metabolism in skeletal muscle.
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Affiliation(s)
- Tzu-Chieh Chen
- Metabolic Biology Graduate Program, University of California Berkeley, Berkeley, California, USA; Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA
| | - Taiyi Kuo
- Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA; Endocrinology Graduate Program, University of California Berkeley, Berkeley, California, USA
| | - Mohamad Dandan
- Metabolic Biology Graduate Program, University of California Berkeley, Berkeley, California, USA; Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA
| | - Rebecca A Lee
- Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA; Endocrinology Graduate Program, University of California Berkeley, Berkeley, California, USA
| | - Maggie Chang
- Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA; Endocrinology Graduate Program, University of California Berkeley, Berkeley, California, USA
| | - Sneha D Villivalam
- Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA; Endocrinology Graduate Program, University of California Berkeley, Berkeley, California, USA
| | - Szu-Chi Liao
- Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA; Endocrinology Graduate Program, University of California Berkeley, Berkeley, California, USA
| | - Damian Costello
- Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA; Endocrinology Graduate Program, University of California Berkeley, Berkeley, California, USA
| | - Mahalakshmi Shankaran
- Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA
| | - Hussein Mohammed
- Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA
| | - Sona Kang
- Metabolic Biology Graduate Program, University of California Berkeley, Berkeley, California, USA; Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA; Endocrinology Graduate Program, University of California Berkeley, Berkeley, California, USA
| | - Marc K Hellerstein
- Metabolic Biology Graduate Program, University of California Berkeley, Berkeley, California, USA; Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA; Endocrinology Graduate Program, University of California Berkeley, Berkeley, California, USA
| | - Jen-Chywan Wang
- Metabolic Biology Graduate Program, University of California Berkeley, Berkeley, California, USA; Department of Nutritional Sciences & Toxicology, University of California Berkeley, Berkeley, California, USA; Endocrinology Graduate Program, University of California Berkeley, Berkeley, California, USA.
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Wang G, Yu Y, Cai W, Batista TM, Suk S, Noh HL, Hirshman M, Nigro P, Li ME, Softic S, Goodyear L, Kim JK, Kahn CR. Muscle-Specific Insulin Receptor Overexpression Protects Mice From Diet-Induced Glucose Intolerance but Leads to Postreceptor Insulin Resistance. Diabetes 2020; 69:2294-2309. [PMID: 32868340 PMCID: PMC7576573 DOI: 10.2337/db20-0439] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 08/25/2020] [Indexed: 12/22/2022]
Abstract
Skeletal muscle insulin resistance is a prominent early feature in the pathogenesis of type 2 diabetes. In attempt to overcome this defect, we generated mice overexpressing insulin receptors (IR) specifically in skeletal muscle (IRMOE). On normal chow, IRMOE mice have body weight similar to that of controls but an increase in lean mass and glycolytic muscle fibers and reduced fat mass. IRMOE mice also show higher basal phosphorylation of IR, IRS-1, and Akt in muscle and improved glucose tolerance compared with controls. When challenged with high-fat diet (HFD), IRMOE mice are protected from diet-induced obesity. This is associated with reduced inflammation in fat and liver, improved glucose tolerance, and improved systemic insulin sensitivity. Surprisingly, however, in both chow and HFD-fed mice, insulin-stimulated Akt phosphorylation is significantly reduced in muscle of IRMOE mice, indicating postreceptor insulin resistance. RNA sequencing reveals downregulation of several postreceptor signaling proteins that contribute to this resistance. Thus, enhancing early insulin signaling in muscle by overexpression of the IR protects mice from diet-induced obesity and its effects on glucose metabolism. However, chronic overstimulation of this pathway leads to postreceptor desensitization, indicating the critical balance between normal signaling and hyperstimulation of the insulin signaling pathway.
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Affiliation(s)
- Guoxiao Wang
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Yingying Yu
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Weikang Cai
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
- Department of Biomedical Sciences, New York Institute of Technology College of Osteopathic Medicine, Old Westbury, NY
| | - Thiago M Batista
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Sujin Suk
- Program in Molecular Medicine and Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Hye Lim Noh
- Program in Molecular Medicine and Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - Michael Hirshman
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Pasquale Nigro
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Mengyao Ella Li
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Samir Softic
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
- Divisions of Pediatric Gastroenterology and Pharmacology and Nutritional Sciences, University of Kentucky College of Medicine, Lexington, KY
| | - Laurie Goodyear
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
| | - Jason K Kim
- Program in Molecular Medicine and Division of Endocrinology, Metabolism, and Diabetes, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
| | - C Ronald Kahn
- Section on Integrative Physiology and Metabolism, Joslin Diabetes Center, Harvard Medical School, Boston, MA
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Gene Expression Profiling of Type 2 Diabetes Mellitus by Bioinformatics Analysis. COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2020; 2020:9602016. [PMID: 33149760 PMCID: PMC7603564 DOI: 10.1155/2020/9602016] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Revised: 07/22/2020] [Accepted: 08/03/2020] [Indexed: 02/07/2023]
Abstract
Objective The aim of this study was to identify the candidate genes in type 2 diabetes mellitus (T2DM) and explore their potential mechanisms. Methods The gene expression profile GSE26168 was downloaded from the Gene Expression Omnibus (GEO) database. The online tool GEO2R was used to obtain differentially expressed genes (DEGs). Gene Ontology (GO) term enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed by using Metascape for annotation, visualization, and comprehensive discovery. The protein-protein interaction (PPI) network of DEGs was constructed by using Cytoscape software to find the candidate genes and key pathways. Results A total of 981 DEGs were found in T2DM, including 301 upregulated genes and 680 downregulated genes. GO analyses from Metascape revealed that DEGs were significantly enriched in cell differentiation, cell adhesion, intracellular signal transduction, and regulation of protein kinase activity. KEGG pathway analysis revealed that DEGs were mainly enriched in the cAMP signaling pathway, Rap1 signaling pathway, regulation of lipolysis in adipocytes, PI3K-Akt signaling pathway, MAPK signaling pathway, and so on. On the basis of the PPI network of the DEGs, the following 6 candidate genes were identified: PIK3R1, RAC1, GNG3, GNAI1, CDC42, and ITGB1. Conclusion Our data provide a comprehensive bioinformatics analysis of genes, functions, and pathways, which may be related to the pathogenesis of T2DM.
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10
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Kwok A, Zvetkova I, Virtue S, Luijten I, Huang-Doran I, Tomlinson P, Bulger DA, West J, Murfitt S, Griffin J, Alam R, Hart D, Knox R, Voshol P, Vidal-Puig A, Jensen J, O'Rahilly S, Semple RK. Truncation of Pik3r1 causes severe insulin resistance uncoupled from obesity and dyslipidaemia by increased energy expenditure. Mol Metab 2020; 40:101020. [PMID: 32439336 PMCID: PMC7385515 DOI: 10.1016/j.molmet.2020.101020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 05/05/2020] [Accepted: 05/12/2020] [Indexed: 12/30/2022] Open
Abstract
OBJECTIVE Insulin signalling via phosphoinositide 3-kinase (PI3K) requires PIK3R1-encoded regulatory subunits. C-terminal PIK3R1 mutations cause SHORT syndrome, as well as lipodystrophy and insulin resistance (IR), surprisingly without fatty liver or metabolic dyslipidaemia. We sought to investigate this discordance. METHODS The human pathogenic Pik3r1 Y657∗ mutation was knocked into mice by homologous recombination. Growth, body composition, bioenergetic and metabolic profiles were investigated on chow and high-fat diet (HFD). We examined adipose and liver histology, and assessed liver responses to fasting and refeeding transcriptomically. RESULTS Like humans with SHORT syndrome, Pik3r1WT/Y657∗ mice were small with severe IR, and adipose expansion on HFD was markedly reduced. Also as in humans, plasma lipid concentrations were low, and insulin-stimulated hepatic lipogenesis was not increased despite hyperinsulinemia. At odds with lipodystrophy, however, no adipocyte hypertrophy nor adipose inflammation was found. Liver lipogenic gene expression was not significantly altered, and unbiased transcriptomics showed only minor changes, including evidence of reduced endoplasmic reticulum stress in the fed state and diminished Rictor-dependent transcription on fasting. Increased energy expenditure, which was not explained by hyperglycaemia nor intestinal malabsorption, provided an alternative explanation for the uncoupling of IR from dyslipidaemia. CONCLUSIONS Pik3r1 dysfunction in mice phenocopies the IR and reduced adiposity without lipotoxicity of human SHORT syndrome. Decreased adiposity may not reflect bona fide lipodystrophy, but rather, increased energy expenditure, and we suggest that further study of brown adipose tissue in both humans and mice is warranted.
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Affiliation(s)
- Albert Kwok
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Ilona Zvetkova
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Sam Virtue
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Ineke Luijten
- Centre for Cardiovascular Science, University of Edinburgh, 47 Little France Crescent, Edinburgh, UK
| | - Isabel Huang-Doran
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Patsy Tomlinson
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - David A Bulger
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - James West
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Steven Murfitt
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK
| | - Julian Griffin
- Department of Biochemistry and Cambridge Systems Biology Centre, University of Cambridge, Cambridge, UK; Biomolecular Medicine, Division of Systems Medicine, Department of Metabolism, Digestion and Reproduction, Medicine, Imperial College London, The Sir Alexander Fleming Building, London, UK
| | - Rafeah Alam
- Laboratory of Lymphocyte Signalling and Development, The Babraham Institute, Cambridge, UK
| | - Daniel Hart
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Rachel Knox
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Peter Voshol
- Louis Bolk Institute, Kosterijland 3-5, NL-3981 AJ, Bunnik, the Netherlands
| | - Antonio Vidal-Puig
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Jørgen Jensen
- Department of Physical Performance, Norwegian School of Sport Sciences, P.O. Box 4014, Ulleval Stadion, 0806 Oslo, Norway
| | - Stephen O'Rahilly
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
| | - Robert K Semple
- Centre for Cardiovascular Science, University of Edinburgh, 47 Little France Crescent, Edinburgh, UK; The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK; MRC Metabolic Diseases Unit, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK.
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11
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Park SW, Lee JM. Emerging Roles of BRD7 in Pathophysiology. Int J Mol Sci 2020; 21:ijms21197127. [PMID: 32992509 PMCID: PMC7583729 DOI: 10.3390/ijms21197127] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 09/20/2020] [Accepted: 09/23/2020] [Indexed: 12/16/2022] Open
Abstract
Bromodomain is a conserved structural module found in many chromatin-associated proteins. Bromodomain-containing protein 7 (BRD7) is a member of the bromodomain-containing protein family, and was discovered two decades ago as a protein that is downregulated in nasopharyngeal carcinoma. Since then, BRD7 has been implicated in a variety of cellular processes, including chromatin remodeling, transcriptional regulation, and cell cycle progression. Decreased BRD7 activity underlies the pathophysiological properties of various diseases in different organs. BRD7 plays an important role in the pathogenesis of many cancers and, more recently, its roles in the regulation of metabolism and obesity have also been highlighted. Here, we review the involvement of BRD7 in a variety of pathophysiological conditions, with a focus on glucose homeostasis, obesity, and cancer.
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Affiliation(s)
- Sang Won Park
- Division of Endocrinology, Boston Children’s Hospital, Boston, MA 02115, USA;
- Department of Pediatrics, Harvard Medical School, Boston, MA 02115, USA
- Correspondence:
| | - Junsik M. Lee
- Division of Endocrinology, Boston Children’s Hospital, Boston, MA 02115, USA;
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12
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Anthrax lethal factor cleaves regulatory subunits of phosphoinositide-3 kinase to contribute to toxin lethality. Nat Microbiol 2020; 5:1464-1471. [PMID: 32895527 DOI: 10.1038/s41564-020-0782-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Accepted: 07/28/2020] [Indexed: 11/08/2022]
Abstract
Anthrax lethal toxin (LT), produced by Bacillus anthracis, comprises a receptor-binding moiety, protective antigen and the lethal factor (LF) protease1,2. Although LF is known to cleave mitogen-activated protein kinase kinases (MEKs/MKKs) and some variants of the NLRP1 inflammasome sensor, targeting of these pathways does not explain the lethality of anthrax toxin1,2. Here we report that the regulatory subunits of phosphoinositide-3 kinase (PI3K)-p85α (PIK3R1) and p85β (PIK3R2)3,4-are substrates of LF. Cleavage of these proteins in a proline-rich region between their N-terminal Src homology and Bcr homology domains disrupts homodimer formation and impacts PI3K signalling. Mice carrying a mutated p85α that cannot be cleaved by LF show a greater resistance to anthrax toxin challenge. The LF(W271A) mutant cleaves p85α with lower efficiency and is non-toxic to mice but can regain lethality when combined with PI3K pathway inhibitors. We provide evidence that LF targets two signalling pathways that are essential for growth and metabolism and that the disabling of both pathways is likely necessary for lethal anthrax infection.
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13
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Oleic Acid Protects Against Insulin Resistance by Regulating the Genes Related to the PI3K Signaling Pathway. J Clin Med 2020; 9:jcm9082615. [PMID: 32806641 PMCID: PMC7463472 DOI: 10.3390/jcm9082615] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/28/2020] [Accepted: 08/10/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND The effects of different types of fatty acids on the gene expression of key players in the IRS1/PI3K signaling pathway have been poorly studied. MATERIAL AND METHODS We analyzed IRS1, p85α, and p110β mRNA expression and the fatty acid composition of phospholipids in visceral adipose tissue from patients with morbid obesity and from non-obese patients. Moreover, we analyzed the expression of those genes in visceral adipocytes incubated with oleic, linoleic, palmitic and dosahexaenoic acids. RESULTS We found a reduced IRS1 expression in patients with morbid obesity, independent of insulin resistance, and a reduced p110β expression in those with lower insulin resistance. A positive correlation was found between p85α and stearic acid, and between IRS1 and p110β with palmitic and dosahexaenoic acid. In contrast, a negative correlation was found between p85α and oleic acid, and between IRS1 and p110β with linoleic, arachidonic and adrenic acid. Incubation with palmitic acid decreased IRS1 expression. p85α was down-regulated after incubation with oleic and dosahexaenoic acid and up-regulated with palmitic acid. p110β expression was increased and decreased after incubation with oleic and palmitic acid, respectively. The ratio p85α/p110β was decreased by oleic and dosahexaenoic acid and increased by palmitic acid. CONCLUSIONS Our in vitro results suggest a detrimental role of palmitic acid on the expression of gene related to insulin signaling pathway, with oleic acid being the one with the higher and more beneficial effects. DHA had a slight beneficial effect. Fatty acid-induced regulation of genes related to the IRS1/PI3K pathway may be a novel mechanism by which fatty acids regulate insulin sensitivity in visceral adipocytes.
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14
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Shorning BY, Dass MS, Smalley MJ, Pearson HB. The PI3K-AKT-mTOR Pathway and Prostate Cancer: At the Crossroads of AR, MAPK, and WNT Signaling. Int J Mol Sci 2020; 21:E4507. [PMID: 32630372 PMCID: PMC7350257 DOI: 10.3390/ijms21124507] [Citation(s) in RCA: 314] [Impact Index Per Article: 78.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/22/2020] [Accepted: 06/22/2020] [Indexed: 12/13/2022] Open
Abstract
Oncogenic activation of the phosphatidylinositol-3-kinase (PI3K), protein kinase B (PKB/AKT), and mammalian target of rapamycin (mTOR) pathway is a frequent event in prostate cancer that facilitates tumor formation, disease progression and therapeutic resistance. Recent discoveries indicate that the complex crosstalk between the PI3K-AKT-mTOR pathway and multiple interacting cell signaling cascades can further promote prostate cancer progression and influence the sensitivity of prostate cancer cells to PI3K-AKT-mTOR-targeted therapies being explored in the clinic, as well as standard treatment approaches such as androgen-deprivation therapy (ADT). However, the full extent of the PI3K-AKT-mTOR signaling network during prostate tumorigenesis, invasive progression and disease recurrence remains to be determined. In this review, we outline the emerging diversity of the genetic alterations that lead to activated PI3K-AKT-mTOR signaling in prostate cancer, and discuss new mechanistic insights into the interplay between the PI3K-AKT-mTOR pathway and several key interacting oncogenic signaling cascades that can cooperate to facilitate prostate cancer growth and drug-resistance, specifically the androgen receptor (AR), mitogen-activated protein kinase (MAPK), and WNT signaling cascades. Ultimately, deepening our understanding of the broader PI3K-AKT-mTOR signaling network is crucial to aid patient stratification for PI3K-AKT-mTOR pathway-directed therapies, and to discover new therapeutic approaches for prostate cancer that improve patient outcome.
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Affiliation(s)
| | | | | | - Helen B. Pearson
- The European Cancer Stem Cell Research Institute, Cardiff University, Hadyn Ellis Building, Maindy Road, Cardiff CF24 4HQ, Wales, UK; (B.Y.S.); (M.S.D.); (M.J.S.)
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15
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Czech MP. Mechanisms of insulin resistance related to white, beige, and brown adipocytes. Mol Metab 2020; 34:27-42. [PMID: 32180558 PMCID: PMC6997501 DOI: 10.1016/j.molmet.2019.12.014] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 12/21/2019] [Accepted: 12/23/2019] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The diminished glucose lowering effect of insulin in obesity, called "insulin resistance," is associated with glucose intolerance, type 2 diabetes, and other serious maladies. Many publications on this topic have suggested numerous hypotheses on the molecular and cellular disruptions that contribute to the syndrome. However, significant uncertainty remains on the mechanisms of its initiation and long-term maintenance. SCOPE OF REVIEW To simplify insulin resistance analysis, this review focuses on the unifying concept that adipose tissue is a central regulator of systemic glucose homeostasis by controlling liver and skeletal muscle metabolism. Key aspects of adipose function related to insulin resistance reviewed are: 1) the modes by which specific adipose tissues control hepatic glucose output and systemic glucose disposal, 2) recently acquired understanding of the underlying mechanisms of these modes of regulation, and 3) the steps in these pathways adversely affected by obesity that cause insulin resistance. MAJOR CONCLUSIONS Adipocyte heterogeneity is required to mediate the multiple pathways that control systemic glucose tolerance. White adipocytes specialize in sequestering triglycerides away from the liver, muscle, and other tissues to limit toxicity. In contrast, brown/beige adipocytes are very active in directly taking up glucose in response to β adrenergic signaling and insulin and enhancing energy expenditure. Nonetheless, white, beige, and brown adipocytes all share the common feature of secreting factors and possibly exosomes that act on distant tissues to control glucose homeostasis. Obesity exerts deleterious effects on each of these adipocyte functions to cause insulin resistance.
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Affiliation(s)
- Michael P Czech
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA, USA.
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16
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Zhu G, Shi J, Zhang S, Guo Y, Huang L, Zhao H, Jiang Y, Sun J. Loss of PI3 kinase association improves the sensitivity of secondary mutation of KIT to Imatinib. Cell Biosci 2020; 10:16. [PMID: 32082541 PMCID: PMC7017564 DOI: 10.1186/s13578-020-0377-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 01/16/2020] [Indexed: 12/13/2022] Open
Abstract
Background KIT mutations are the predominant driver mutations in gastrointestinal stromal tumors (GISTs), and targeted therapy against KIT has improved treatment outcome dramatically. However, gaining secondary mutation of KIT confers drug resistance of GISTs leading to treatment failure. Results In this study, we found that secondary mutation of KIT dramatically increases the ligand-independent activation of the receptor and their resistance to the often used KIT inhibitor Imatinib in the treatment of GISTs. PI3 kinase plays essential roles in the cell transformation mediated by the primary mutation of KIT. We found that loss of PI3 kinase association, but not the inhibition of the lipid kinase activity of PI3 kinase, inhibits the ligand-independent activation of secondary mutations of KIT, and increases their sensitivity to Imatinib, and loss of PI3 kinase association inhibits secondary mutations of KIT mediated cell survival and proliferation in vitro. The in vivo assay further showed that the growth of tumors carrying secondary mutations of KIT is more sensitive to Imatinib when PI3 kinase association is blocked while inhibition of the lipid kinase activity of PI3 kinase cannot inhibit tumor growth, indicating that PI3 kinase is important for the drug resistance of secondary mutation of KIT independent of the lipid kinase activity of PI3 kinase. Conclusions Our results suggested that PI3 kinase is necessary for the ligand-independent activation of secondary mutations of KIT, and loss of PI3 kinase association improves the sensitivity of secondary mutations to the targeted therapy independent of the lipid kinase activity of PI3 kinase.
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Affiliation(s)
- Guangrong Zhu
- 1School of Basic Medical Sciences, Ningxia Medical University, No. 1160 Shengli Street, Yinchuan, 750004 China
| | - Jun Shi
- 1School of Basic Medical Sciences, Ningxia Medical University, No. 1160 Shengli Street, Yinchuan, 750004 China
| | - Shaoting Zhang
- 1School of Basic Medical Sciences, Ningxia Medical University, No. 1160 Shengli Street, Yinchuan, 750004 China
| | - Yue Guo
- 2Key Laboratory for Regenerative Medicine, Ministry of Education, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong SAR, China
| | - Ling Huang
- 1School of Basic Medical Sciences, Ningxia Medical University, No. 1160 Shengli Street, Yinchuan, 750004 China
| | - Hui Zhao
- 2Key Laboratory for Regenerative Medicine, Ministry of Education, School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Hong Kong, Hong Kong SAR, China.,3Kunming Institute of Zoology, Chinese Academy of Sciences-The Chinese University of Hong Kong Joint Laboratory of Bioresources and Molecular Research of Common Diseases, Hong Kong, Hong Kong SAR, China
| | - Yideng Jiang
- 1School of Basic Medical Sciences, Ningxia Medical University, No. 1160 Shengli Street, Yinchuan, 750004 China.,4NHC Key Laboratory of Metabolic Cardiovascular Diseases Research (Ningxia Medical University), Yinchuan, China.,Ningxia Key Laboratory of Vascular Injury and Repair Research, Yinchuan, China
| | - Jianmin Sun
- 1School of Basic Medical Sciences, Ningxia Medical University, No. 1160 Shengli Street, Yinchuan, 750004 China.,6Division of Translational Cancer Research, Lund Stem Cell Center, Department of Laboratory Medicine, Lund University, Lund, Sweden
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17
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Gomez-Hernandez A, Lopez-Pastor AR, Rubio-Longas C, Majewski P, Beneit N, Viana-Huete V, García-Gómez G, Fernandez S, Hribal ML, Sesti G, Escribano O, Benito M. Specific knockout of p85α in brown adipose tissue induces resistance to high-fat diet-induced obesity and its metabolic complications in male mice. Mol Metab 2019; 31:1-13. [PMID: 31918912 PMCID: PMC6977168 DOI: 10.1016/j.molmet.2019.10.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 10/14/2019] [Accepted: 10/30/2019] [Indexed: 12/19/2022] Open
Abstract
Objective An increase in mass and/or brown adipose tissue (BAT) functionality leads to an increase in energy expenditure, which may be beneficial for the prevention and treatment of obesity. Moreover, distinct class I PI3K isoforms can participate in metabolic control as well as in systemic dysfunctions associated with obesity. In this regard, we analyzed in vivo whether the lack of p85α in BAT (BATp85αKO) could modulate the activity and insulin signaling of this tissue, thereby improving diet-induced obesity and its associated metabolic complications. Methods We generated BATp85αKO mice using Cre-LoxP technology, specifically deleting p85α in a conditional manner. To characterize this new mouse model, we used mice of 6 and 12 months of age. In addition, BATp85αKO mice were submitted to a high-fat diet (HFD) to challenge BAT functionality. Results Our results suggest that the loss of p85α in BAT improves its thermogenic functionality, high-fat diet–induced adiposity and body weight, insulin resistance, and liver steatosis. The potential mechanisms involved in the improvement of obesity include (1) increased insulin signaling and lower activation of JNK in BAT, (2) enhanced insulin receptor isoform B (IRB) expression and association with IRS-1 in BAT, (3) lower production of proinflammatory cytokines by the adipose organ, (4) increased iWAT browning, and (5) improved liver steatosis. Conclusions Our results provide new mechanisms involved in the resistance to obesity development, supporting the hypothesis that the gain of BAT activity induced by the lack of p85α has a direct impact on the prevention of diet-induced obesity and its associated metabolic complications. The lack of p85α in brown adipose tissue confers obesity resistance. BATp85αKO mice show improved thermogenic function, fatty liver and insulin resistance. High IRB levels in BAT and iWAT browning might explain the improvement of obesity. Increase in BAT functionality has a direct impact on the prevention of obesity.
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Affiliation(s)
- Almudena Gomez-Hernandez
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Spain; Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain; CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Spain.
| | - Andrea R Lopez-Pastor
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Spain; Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain.
| | - Carlota Rubio-Longas
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Spain.
| | - Patrik Majewski
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Spain.
| | - Nuria Beneit
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Spain; Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain.
| | - Vanesa Viana-Huete
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Spain; Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain.
| | - Gema García-Gómez
- Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain; CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Spain.
| | - Silvia Fernandez
- Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain; CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Spain.
| | - Marta Letizia Hribal
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, Italy.
| | - Giorgio Sesti
- Department of Medical and Surgical Sciences, University Magna Graecia of Catanzaro, Italy.
| | - Oscar Escribano
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Spain; Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain; CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Spain.
| | - Manuel Benito
- Biochemistry and Molecular Biology Department, School of Pharmacy, Complutense University of Madrid, Spain; Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain; CIBER of Diabetes and Associated Metabolic Diseases (CIBERDEM), Spain.
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18
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Solheim MH, Winnay JN, Batista TM, Molven A, Njølstad PR, Kahn CR. Mice Carrying a Dominant-Negative Human PI3K Mutation Are Protected From Obesity and Hepatic Steatosis but Not Diabetes. Diabetes 2018; 67:1297-1309. [PMID: 29724723 PMCID: PMC6014554 DOI: 10.2337/db17-1509] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/23/2018] [Indexed: 12/20/2022]
Abstract
Phosphatidylinositol 3-kinase (PI3K) plays a central role in insulin signaling, glucose metabolism, cell growth, cell development, and apoptosis. A heterozygous missense mutation (R649W) in the p85α regulatory subunit gene of PI3K (PIK3R1) has been identified in patients with SHORT (Short stature, Hyperextensibility/Hernia, Ocular depression, Rieger anomaly, and Teething delay) syndrome, a disorder characterized by postnatal growth retardation, insulin resistance, and partial lipodystrophy. Knock-in mice with the same heterozygous mutation mirror the human phenotype. In this study, we show that Pik3r1 R649W knock-in mice fed a high-fat diet (HFD) have reduced weight gain and adipose accumulation. This is accompanied by reduced expression of several genes involved in lipid metabolism. Interestingly, despite the lower level of adiposity, the HFD knock-in mice are more hyperglycemic and more insulin-resistant than HFD-fed control mice. Likewise, when crossed with genetically obese ob/ob mice, the ob/ob mice carrying the heterozygous R649W mutation were protected from obesity and hepatic steatosis but developed a severe diabetic state. Together, our data demonstrate a central role of PI3K in development of obesity and fatty liver disease, separating these effects from the role of PI3K in insulin resistance and the resultant hyperglycemia.
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Affiliation(s)
- Marie H Solheim
- Joslin Diabetes Center and Harvard Medical School, Boston, MA
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
| | | | | | - Anders Molven
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Gade Laboratory for Pathology, Department of Clinical Medicine, University of Bergen, Bergen, Norway
- Department of Pathology, Haukeland University Hospital, Bergen, Norway
| | - Pål R Njølstad
- KG Jebsen Center for Diabetes Research, Department of Clinical Science, University of Bergen, Bergen, Norway
- Department of Pediatrics and Adolescent Medicine, Haukeland University Hospital, Bergen, Norway
| | - C Ronald Kahn
- Joslin Diabetes Center and Harvard Medical School, Boston, MA
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Martins VF, Tahvilian S, Kang JH, Svensson K, Hetrick B, Chick WS, Schenk S, McCurdy CE. Calorie Restriction-Induced Increase in Skeletal Muscle Insulin Sensitivity Is Not Prevented by Overexpression of the p55α Subunit of Phosphoinositide 3-Kinase. Front Physiol 2018; 9:789. [PMID: 29997524 PMCID: PMC6030672 DOI: 10.3389/fphys.2018.00789] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2018] [Accepted: 06/06/2018] [Indexed: 01/26/2023] Open
Abstract
Introduction: The Phosphoinositide 3-kinase (PI3K) signaling pathway plays an important role in skeletal muscle insulin-stimulated glucose uptake. While whole-body and tissue specific knockout (KO) of individual or combinations of the regulatory subunits of PI3K (p85α, p55α, and p50α or p85β); increase insulin sensitivity, no study has examined whether increasing the expression of the individual regulatory subunits would inhibit insulin action in vivo. Therefore, the objective of this study was to determine whether skeletal muscle-specific overexpression of the p55α regulatory subunit of PI3K impairs skeletal muscle insulin sensitivity, or prevents its enhancement by caloric restriction. Methods: We developed a novel "floxed" mouse that, through the Cre-LoxP approach, allows for tamoxifen (TMX)-inducible and skeletal muscle-specific overexpression of the p55α subunit of PI3K (referred to as, 'p55α-mOX'). Beginning at 10 weeks of age, p55α-mOX mice and their floxed littermates (referred to as wildtype [WT]) either continued with free access to food (ad libitum; AL), or were switched to a calorie restricted diet (CR; 60% of AL intake) for 20 days. We measured body composition, whole-body energy expenditure, oral glucose tolerance and ex vivo skeletal muscle insulin sensitivity in isolated soleus and extensor digitorum longus muscles using the 2-deoxy-glucose (2DOG) uptake method. Results: p55α mRNA and protein expression was increased ∼2 fold in muscle from p55α-mOX versus WT mice. There were no differences in energy expenditure, total activity, or food intake of AL-fed mice between genotypes. Body weight, fat and lean mass, tissue weights, and fasting glucose and insulin were comparable between p55α-mOX and WT mice on AL, and were decreased equally by CR. Interestingly, overexpression of p55α did not impair oral glucose tolerance or skeletal muscle insulin signaling or sensitivity, nor did it impact the ability of CR to enhance these parameters. Conclusion: Skeletal muscle-specific overexpression of p55α does not impact skeletal muscle insulin action, suggesting that p85α and/or p50α may be more important regulators of skeletal muscle insulin signaling and sensitivity.
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Affiliation(s)
- Vitor F. Martins
- Department of Orthopaedic Surgery, University of California, San Diego, La Jolla, CA, United States
- Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA, United States
| | - Shahriar Tahvilian
- Department of Orthopaedic Surgery, University of California, San Diego, La Jolla, CA, United States
| | - Ji H. Kang
- Department of Orthopaedic Surgery, University of California, San Diego, La Jolla, CA, United States
| | - Kristoffer Svensson
- Department of Orthopaedic Surgery, University of California, San Diego, La Jolla, CA, United States
| | - Byron Hetrick
- Department of Human Physiology, University of Oregon, Eugene, OR, United States
| | - Wallace S. Chick
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Simon Schenk
- Department of Orthopaedic Surgery, University of California, San Diego, La Jolla, CA, United States
- Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, CA, United States
| | - Carrie E. McCurdy
- Department of Human Physiology, University of Oregon, Eugene, OR, United States
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Sun Y, Ma C, Halgamuge S. The node-weighted Steiner tree approach to identify elements of cancer-related signaling pathways. BMC Bioinformatics 2017; 18:551. [PMID: 29297291 PMCID: PMC5751691 DOI: 10.1186/s12859-017-1958-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Background Cancer constitutes a momentous health burden in our society. Critical information on cancer may be hidden in its signaling pathways. However, even though a large amount of money has been spent on cancer research, some critical information on cancer-related signaling pathways still remains elusive. Hence, new works towards a complete understanding of cancer-related signaling pathways will greatly benefit the prevention, diagnosis, and treatment of cancer. Results We propose the node-weighted Steiner tree approach to identify important elements of cancer-related signaling pathways at the level of proteins. This new approach has advantages over previous approaches since it is fast in processing large protein-protein interaction networks. We apply this new approach to identify important elements of two well-known cancer-related signaling pathways: PI3K/Akt and MAPK. First, we generate a node-weighted protein-protein interaction network using protein and signaling pathway data. Second, we modify and use two preprocessing techniques and a state-of-the-art Steiner tree algorithm to identify a subnetwork in the generated network. Third, we propose two new metrics to select important elements from this subnetwork. On a commonly used personal computer, this new approach takes less than 2 s to identify the important elements of PI3K/Akt and MAPK signaling pathways in a large node-weighted protein-protein interaction network with 16,843 vertices and 1,736,922 edges. We further analyze and demonstrate the significance of these identified elements to cancer signal transduction by exploring previously reported experimental evidences. Conclusions Our node-weighted Steiner tree approach is shown to be both fast and effective to identify important elements of cancer-related signaling pathways. Furthermore, it may provide new perspectives into the identification of signaling pathways for other human diseases.
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Affiliation(s)
- Yahui Sun
- Department of Mechanical Engineering, The University of Melbourne, Melbourne, 3010, Australia.
| | - Chenkai Ma
- Department of Surgery, The University of Melbourne, Melbourne, 3010, Australia
| | - Saman Halgamuge
- Research School of Engineering, College of Engineering & Computer Science, The Australian National University, Canberra, 2601, ACT, Australia
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A Comprehensive Survey of the Roles of Highly Disordered Proteins in Type 2 Diabetes. Int J Mol Sci 2017; 18:ijms18102010. [PMID: 28934129 PMCID: PMC5666700 DOI: 10.3390/ijms18102010] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 09/04/2017] [Accepted: 09/12/2017] [Indexed: 01/03/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a chronic and progressive disease that is strongly associated with hyperglycemia (high blood sugar) related to either insulin resistance or insufficient insulin production. Among the various molecular events and players implicated in the manifestation and development of diabetes mellitus, proteins play several important roles. The Kyoto Encyclopedia of Genes and Genomes (KEGG) database has information on 34 human proteins experimentally shown to be related to the T2DM pathogenesis. It is known that many proteins associated with different human maladies are intrinsically disordered as a whole, or contain intrinsically disordered regions. The presented study shows that T2DM is not an exception to this rule, and many proteins known to be associated with pathogenesis of this malady are intrinsically disordered. The multiparametric bioinformatics analysis utilizing several computational tools for the intrinsic disorder characterization revealed that IRS1, IRS2, IRS4, MAFA, PDX1, ADIPO, PIK3R2, PIK3R5, SoCS1, and SoCS3 are expected to be highly disordered, whereas VDCC, SoCS2, SoCS4, JNK9, PRKCZ, PRKCE, insulin, GCK, JNK8, JNK10, PYK, INSR, TNF-α, MAPK3, and Kir6.2 are classified as moderately disordered proteins, and GLUT2, GLUT4, mTOR, SUR1, MAPK1, IKKA, PRKCD, PIK3CB, and PIK3CA are predicted as mostly ordered. More focused computational analyses and intensive literature mining were conducted for a set of highly disordered proteins related to T2DM. The resulting work represents a comprehensive survey describing the major biological functions of these proteins and functional roles of their intrinsically disordered regions, which are frequently engaged in protein–protein interactions, and contain sites of various posttranslational modifications (PTMs). It is also shown that intrinsic disorder-associated PTMs may play important roles in controlling the functions of these proteins. Consideration of the T2DM proteins from the perspective of intrinsic disorder provides useful information that can potentially lead to future experimental studies that may uncover latent and novel pathways associated with the disease.
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22
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McGinnis GR, Tang Y, Brewer RA, Brahma MK, Stanley HL, Shanmugam G, Rajasekaran NS, Rowe GC, Frank SJ, Wende AR, Abel ED, Taegtmeyer H, Litovsky S, Darley-Usmar V, Zhang J, Chatham JC, Young ME. Genetic disruption of the cardiomyocyte circadian clock differentially influences insulin-mediated processes in the heart. J Mol Cell Cardiol 2017; 110:80-95. [PMID: 28736261 PMCID: PMC5586500 DOI: 10.1016/j.yjmcc.2017.07.005] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 07/09/2017] [Accepted: 07/19/2017] [Indexed: 12/21/2022]
Abstract
Cardiovascular physiology exhibits time-of-day-dependent oscillations, which are mediated by both extrinsic (e.g., environment/behavior) and intrinsic (e.g., circadian clock) factors. Disruption of circadian rhythms negatively affects multiple cardiometabolic parameters. Recent studies suggest that the cardiomyocyte circadian clock directly modulates responsiveness of the heart to metabolic stimuli (e.g., fatty acids) and stresses (e.g., ischemia/reperfusion). The aim of this study was to determine whether genetic disruption of the cardiomyocyte circadian clock impacts insulin-regulated pathways in the heart. Genetic disruption of the circadian clock in cardiomyocyte-specific Bmal1 knockout (CBK) and cardiomyocyte-specific Clock mutant (CCM) mice altered expression (gene and protein) of multiple insulin signaling components in the heart, including p85α and Akt. Both baseline and insulin-mediated Akt activation was augmented in CBK and CCM hearts (relative to littermate controls). However, insulin-mediated glucose utilization (both oxidative and non-oxidative) and AS160 phosphorylation were attenuated in CBK hearts, potentially secondary to decreased Inhibitor-1. Consistent with increased Akt activation in CBK hearts, mTOR signaling was persistently increased, which was associated with attenuation of autophagy, augmented rates of protein synthesis, and hypertrophy. Importantly, pharmacological inhibition of mTOR (rapamycin; 10days) normalized cardiac size in CBK mice. These data suggest that disruption of cardiomyocyte circadian clock differentially influences insulin-regulated processes, and provide new insights into potential pathologic mediators following circadian disruption.
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Affiliation(s)
- Graham R McGinnis
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Yawen Tang
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Rachel A Brewer
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Manoja K Brahma
- Division of Molecular Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Haley L Stanley
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Gobinath Shanmugam
- Division of Molecular Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Namakkal Soorappan Rajasekaran
- Division of Molecular Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Glenn C Rowe
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Stuart J Frank
- Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Adam R Wende
- Division of Molecular Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - E Dale Abel
- Division of Endocrinology and Metabolism, Department of Medicine and Fraternal Order of Eagles Diabetes Research Center, University of Iowa, Iowa City, IA, USA
| | - Heinrich Taegtmeyer
- Division of Cardiology, Department of Internal Medicine, McGovern Medical School UT Health Science Center, Houston, TX, USA
| | - Silvio Litovsky
- Division of Molecular Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Victor Darley-Usmar
- Division of Molecular Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jianhua Zhang
- Division of Molecular Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - John C Chatham
- Division of Molecular Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Martin E Young
- Division of Cardiovascular Disease, Department of Medicine, University of Alabama at Birmingham, Birmingham, AL, USA.
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23
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Chaudhari A, Ejeskär K, Wettergren Y, Kahn CR, Rotter Sopasakis V. Hepatic deletion of p110α and p85α results in insulin resistance despite sustained IRS1-associated phosphatidylinositol kinase activity. F1000Res 2017; 6:1600. [PMID: 29983910 PMCID: PMC6020741 DOI: 10.12688/f1000research.12418.1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 08/25/2017] [Indexed: 09/27/2023] Open
Abstract
BACKGROUND Class IA phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) is an integral mediator of insulin signaling. The p110 catalytic and p85 regulatory subunits of PI3K are the products of separate genes, and while they come together to make the active heterodimer, they have opposing roles in insulin signaling and action. Deletion of hepatic p110α results in an impaired insulin signal and severe insulin resistance, whereas deletion of hepatic p85α results in improved insulin sensitivity due to sustained levels of phosphatidylinositol (3,4,5)-trisphosphate. Here, we created mice with combined hepatic deletion of p110α and p85α (L-DKO) to study the impact on insulin signaling and whole body glucose homeostasis. METHODS Six-week old male flox control and L-DKO mice were studied over a period of 18 weeks, during which weight and glucose levels were monitored, and glucose tolerance tests, insulin tolerance test and pyruvate tolerance test were performed. Fasting insulin, insulin signaling mediators, PI3K activity and insulin receptor substrate (IRS)1-associated phosphatidylinositol kinase activity were examined at 10 weeks. Liver, muscle and white adipose tissue weight was recorded at 10 weeks and 25 weeks. RESULTS The L-DKO mice showed a blunted insulin signal downstream of PI3K, developed markedly impaired glucose tolerance, hyperinsulinemia and had decreased liver and adipose tissue weights. Surprisingly, however, these mice displayed normal hepatic glucose production, normal insulin tolerance, and intact IRS1-associated phosphatidylinositol kinase activity without compensatory upregulated signaling of other classes of PI3K. CONCLUSIONS The data demonstrate an unexpectedly overall mild metabolic phenotype of the L-DKO mice, suggesting that lipid kinases other than PI3Ks might partially compensate for the loss of p110α/p85α by signaling through other nodes than Akt/Protein Kinase B.
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Affiliation(s)
- Aditi Chaudhari
- Wallenberg Laboratory, Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Chemistry and Transfusion Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Katarina Ejeskär
- Institute of Health and Education, Translational Medicine, University of Skövde, Skövde, Sweden
| | - Yvonne Wettergren
- Department of Surgery, University of Gothenburg, Sahlgrenska University Hospital/Östra, Gothenburg, Sweden
| | - C. Ronald Kahn
- Joslin Diabetes Center and Harvard Medical School, One Joslin Place, Boston, MA, USA
| | - Victoria Rotter Sopasakis
- Wallenberg Laboratory, Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Chemistry and Transfusion Medicine, University of Gothenburg, Gothenburg, Sweden
- Joslin Diabetes Center and Harvard Medical School, One Joslin Place, Boston, MA, USA
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24
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Chaudhari A, Ejeskär K, Wettergren Y, Kahn CR, Rotter Sopasakis V. Hepatic deletion of p110α and p85α results in insulin resistance despite sustained IRS1-associated phosphatidylinositol kinase activity. F1000Res 2017; 6:1600. [PMID: 29983910 PMCID: PMC6020741 DOI: 10.12688/f1000research.12418.2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/01/2018] [Indexed: 12/11/2022] Open
Abstract
Background: Class IA phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) is an integral mediator of insulin signaling. The p110 catalytic and p85 regulatory subunits of PI3K are the products of separate genes, and while they come together to make the active heterodimer, they have opposing roles in insulin signaling and action. Deletion of hepatic p110α results in an impaired insulin signal and severe insulin resistance, whereas deletion of hepatic p85α results in improved insulin sensitivity due to sustained levels of phosphatidylinositol (3,4,5)-trisphosphate. Here, we created mice with combined hepatic deletion of p110α and p85α (L-DKO) to study the impact on insulin signaling and whole body glucose homeostasis. Methods: Six-week old male flox control and L-DKO mice were studied over a period of 18 weeks, during which weight and glucose levels were monitored, and glucose tolerance tests, insulin tolerance test and pyruvate tolerance test were performed. Fasting insulin, insulin signaling mediators, PI3K activity and insulin receptor substrate (IRS)1-associated phosphatidylinositol kinase activity were examined at 10 weeks. Liver, muscle and white adipose tissue weight was recorded at 10 weeks and 25 weeks. Results: The L-DKO mice showed a blunted insulin signal downstream of PI3K, developed markedly impaired glucose tolerance, hyperinsulinemia and had decreased liver and adipose tissue weights. Surprisingly, however, these mice displayed normal hepatic glucose production, normal insulin tolerance, and intact IRS1-associated phosphatidylinositol kinase activity without compensatory upregulated signaling of other classes of PI3K. Conclusions: The data demonstrate an unexpectedly overall mild metabolic phenotype of the L-DKO mice, suggesting that lipid kinases other than PI3Ks might partially compensate for the loss of p110α/p85α by signaling through other nodes than Akt/Protein Kinase B.
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Affiliation(s)
- Aditi Chaudhari
- Wallenberg Laboratory, Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Chemistry and Transfusion Medicine, University of Gothenburg, Gothenburg, Sweden
| | - Katarina Ejeskär
- Institute of Health and Education, Translational Medicine, University of Skövde, Skövde, Sweden
| | - Yvonne Wettergren
- Department of Surgery, University of Gothenburg, Sahlgrenska University Hospital/Östra, Gothenburg, Sweden
| | - C. Ronald Kahn
- Joslin Diabetes Center and Harvard Medical School, One Joslin Place, Boston, MA, USA
| | - Victoria Rotter Sopasakis
- Wallenberg Laboratory, Department of Molecular and Clinical Medicine, University of Gothenburg, Gothenburg, Sweden
- Department of Clinical Chemistry and Transfusion Medicine, University of Gothenburg, Gothenburg, Sweden
- Joslin Diabetes Center and Harvard Medical School, One Joslin Place, Boston, MA, USA
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25
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PI3K-p110α mediates the oncogenic activity induced by loss of the novel tumor suppressor PI3K-p85α. Proc Natl Acad Sci U S A 2017. [PMID: 28630349 DOI: 10.1073/pnas.1704706114] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Mutation or loss of the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3K) is emerging as a transforming factor in cancer, but the mechanism of transformation has been controversial. Here we find that hemizygous deletion of the PIK3R1 gene encoding p85α is a frequent event in breast cancer, with PIK3R1 expression significantly reduced in breast tumors. PIK3R1 knockdown transforms human mammary epithelial cells, and genetic ablation of Pik3r1 accelerates a mouse model of HER2/neu-driven breast cancer. We demonstrate that partial loss of p85α increases the amount of p110α-p85 heterodimers bound to active receptors, augmenting PI3K signaling and oncogenic transformation. Pan-PI3K and p110α-selective pharmacological inhibition effectively blocks transformation driven by partial p85α loss both in vitro and in vivo. Together, our data suggest that p85α plays a tumor-suppressive role in transformation, and suggest that p110α-selective therapeutics may be effective in the treatment of breast cancer patients with PIK3R1 loss.
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26
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Huang-Doran I, Tomlinson P, Payne F, Gast A, Sleigh A, Bottomley W, Harris J, Daly A, Rocha N, Rudge S, Clark J, Kwok A, Romeo S, McCann E, Müksch B, Dattani M, Zucchini S, Wakelam M, Foukas LC, Savage DB, Murphy R, O'Rahilly S, Barroso I, Semple RK. Insulin resistance uncoupled from dyslipidemia due to C-terminal PIK3R1 mutations. JCI Insight 2016; 1:e88766. [PMID: 27766312 PMCID: PMC5070960 DOI: 10.1172/jci.insight.88766] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Obesity-related insulin resistance is associated with fatty liver, dyslipidemia, and low plasma adiponectin. Insulin resistance due to insulin receptor (INSR) dysfunction is associated with none of these, but when due to dysfunction of the downstream kinase AKT2 phenocopies obesity-related insulin resistance. We report 5 patients with SHORT syndrome and C-terminal mutations in PIK3R1, encoding the p85α/p55α/p50α subunits of PI3K, which act between INSR and AKT in insulin signaling. Four of 5 patients had extreme insulin resistance without dyslipidemia or hepatic steatosis. In 3 of these 4, plasma adiponectin was preserved, as in insulin receptor dysfunction. The fourth patient and her healthy mother had low plasma adiponectin associated with a potentially novel mutation, p.Asp231Ala, in adiponectin itself. Cells studied from one patient with the p.Tyr657X PIK3R1 mutation expressed abundant truncated PIK3R1 products and showed severely reduced insulin-stimulated association of mutant but not WT p85α with IRS1, but normal downstream signaling. In 3T3-L1 preadipocytes, mutant p85α overexpression attenuated insulin-induced AKT phosphorylation and adipocyte differentiation. Thus, PIK3R1 C-terminal mutations impair insulin signaling only in some cellular contexts and produce a subphenotype of insulin resistance resembling INSR dysfunction but unlike AKT2 dysfunction, implicating PI3K in the pathogenesis of key components of the metabolic syndrome. C-terminal mutations in human PIK3R1 are associated with severe insulin resistance in the absence of dyslipidemia or hepatic steatosis.
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Affiliation(s)
- Isabel Huang-Doran
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Patsy Tomlinson
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Felicity Payne
- Metabolic Disease Group, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Alexandra Gast
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Alison Sleigh
- Wolfson Brain Imaging Centre, University of Cambridge, Cambridge, United Kingdom.,National Institute for Health Research/Wellcome Trust Clinical Research Facility, Cambridge, United Kingdom
| | - William Bottomley
- Metabolic Disease Group, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Julie Harris
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Allan Daly
- Metabolic Disease Group, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Nuno Rocha
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Simon Rudge
- Inositide Laboratory, Babraham Institute, Cambridge, United Kingdom
| | - Jonathan Clark
- Inositide Laboratory, Babraham Institute, Cambridge, United Kingdom
| | - Albert Kwok
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Stefano Romeo
- Department of Molecular and Clinical Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden.,Clinical Nutrition Unit, Department of Medical and Surgical Sciences, University Magna Graecia, Catanzaro, Italy
| | - Emma McCann
- Department of Clinical Genetics, Glan Clwyd Hospital, Rhyl, United Kingdom
| | - Barbara Müksch
- Department of Pediatrics, Children's Hospital, Cologne, Germany
| | - Mehul Dattani
- Section of Genetics and Epigenetics in Health and Disease, Genetics and Genomic Medicine Programme, UCL Institute of Child Health, London, United Kingdom
| | - Stefano Zucchini
- Pediatric Endocrine Unit, S.Orsola-Malpighi Hospital, Bologna, Italy
| | - Michael Wakelam
- Inositide Laboratory, Babraham Institute, Cambridge, United Kingdom
| | - Lazaros C Foukas
- Institute of Healthy Ageing and Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - David B Savage
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Rinki Murphy
- Department of Medicine, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Stephen O'Rahilly
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
| | - Inês Barroso
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom.,Metabolic Disease Group, Wellcome Trust Sanger Institute, Cambridge, United Kingdom
| | - Robert K Semple
- The University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, United Kingdom.,The National Institute for Health Research Cambridge Biomedical Research Centre, Cambridge, United Kingdom
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27
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Insulin resistance and diabetes caused by genetic or diet-induced KBTBD2 deficiency in mice. Proc Natl Acad Sci U S A 2016; 113:E6418-E6426. [PMID: 27708159 DOI: 10.1073/pnas.1614467113] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
We describe a metabolic disorder characterized by lipodystrophy, hepatic steatosis, insulin resistance, severe diabetes, and growth retardation observed in mice carrying N-ethyl-N-nitrosourea (ENU)-induced mutations. The disorder was ascribed to a mutation of kelch repeat and BTB (POZ) domain containing 2 (Kbtbd2) and was mimicked by a CRISPR/Cas9-targeted null allele of the same gene. Kbtbd2 encodes a BTB-Kelch family substrate recognition subunit of the Cullin-3-based E3 ubiquitin ligase. KBTBD2 targeted p85α, the regulatory subunit of the phosphoinositol-3-kinase (PI3K) heterodimer, causing p85α ubiquitination and proteasome-mediated degradation. In the absence of KBTBD2, p85α accumulated to 30-fold greater levels than in wild-type adipocytes, and excessive p110-free p85α blocked the binding of p85α-p110 heterodimers to IRS1, interrupting the insulin signal. Both transplantation of wild-type adipose tissue and homozygous germ line inactivation of the p85α-encoding gene Pik3r1 rescued diabetes and hepatic steatosis phenotypes of Kbtbd2-/- mice. Kbtbd2 was down-regulated in diet-induced obese insulin-resistant mice in a leptin-dependent manner. KBTBD2 is an essential regulator of the insulin-signaling pathway, modulating insulin sensitivity by limiting p85α abundance.
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28
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Winnay JN, Solheim MH, Dirice E, Sakaguchi M, Noh HL, Kang HJ, Takahashi H, Chudasama KK, Kim JK, Molven A, Kahn CR, Njølstad PR. PI3-kinase mutation linked to insulin and growth factor resistance in vivo. J Clin Invest 2016; 126:1401-12. [PMID: 26974159 DOI: 10.1172/jci84005] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 01/28/2016] [Indexed: 12/29/2022] Open
Abstract
The phosphatidylinositol 3-kinase (PI3K) signaling pathway is central to the action of insulin and many growth factors. Heterozygous mutations in the gene encoding the p85α regulatory subunit of PI3K (PIK3R1) have been identified in patients with SHORT syndrome - a disorder characterized by short stature, partial lipodystrophy, and insulin resistance. Here, we evaluated whether SHORT syndrome-associated PIK3R1 mutations account for the pathophysiology that underlies the abnormalities by generating knockin mice that are heterozygous for the Pik3r1Arg649Trp mutation, which is homologous to the mutation found in the majority of affected individuals. Similar to the patients, mutant mice exhibited a reduction in body weight and length, partial lipodystrophy, and systemic insulin resistance. These derangements were associated with a reduced capacity of insulin and other growth factors to activate PI3K in liver, muscle, and fat; marked insulin resistance in liver and fat of mutation-harboring animals; and insulin resistance in vitro in cells derived from these mice. In addition, mutant mice displayed defective insulin secretion and GLP-1 action on islets in vivo and in vitro. These data demonstrate the ability of this heterozygous mutation to alter PI3K activity in vivo and the central role of PI3K in insulin/growth factor action, adipocyte function, and glucose metabolism.
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29
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Di Donato N, Rump A, Mirzaa GM, Alcantara D, Oliver A, Schrock E, Dobyns WB, O’Driscoll M. Identification and Characterization of a Novel Constitutional PIK3CA Mutation in a Child Lacking the Typical Segmental Overgrowth of "PIK3CA-Related Overgrowth Spectrum". Hum Mutat 2016; 37:242-5. [PMID: 26593112 PMCID: PMC4752430 DOI: 10.1002/humu.22933] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 11/09/2015] [Indexed: 11/07/2022]
Abstract
Activating somatic PIK3CA mutations underlie a growing heterogeneous spectrum of segmental overgrowth disorders. We report the identification and evaluation of a novel de novo constitutional PIK3CA mutation (NM_006218.2:c.335T>A, p.Ile112Asn) in a child with congenital megalencephaly and macrosomia. Functional characterization of patient cells using a variety of endpoints demonstrates increased phosphatidylinositol-3-kinase (PI3K) activity. The mutation lies in a linker region adjacent to the p85 (PIK3R2) binding domain of the p110α (PIK3CA) catalytic subunit of PI3K. We show that altered stoichiometry within the p85-p110 complex likely underlies the hyperactive PI3K-AKT-mTOR signaling in this instance. Our findings expand upon the recently proposed "PIK3CA-related overgrowth spectrum" associated with PIKC3A mutations and PI3K hyperactivation, adding constitutional PIK3CA mutations as an underlying cause of megalencephaly and macrosomia in newborns.
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Affiliation(s)
- Nataliya Di Donato
- Institute for Clinical Genetics, Faculty of Medicine Carl Gustav Carus, TU Dresden, Germany
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, USA
| | - Andreas Rump
- Institute for Clinical Genetics, Faculty of Medicine Carl Gustav Carus, TU Dresden, Germany
| | - Ghayda M. Mirzaa
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, USA
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, USA
| | - Diana Alcantara
- Genome Damage & Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, UK
| | - Antony Oliver
- Genome Damage & Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, UK
| | - Evelin Schrock
- Institute for Clinical Genetics, Faculty of Medicine Carl Gustav Carus, TU Dresden, Germany
| | - William B. Dobyns
- Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, USA
- Division of Genetic Medicine, Department of Pediatrics, University of Washington, Seattle, USA
| | - Mark O’Driscoll
- Genome Damage & Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, UK
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30
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Regulation of Glucose Homeostasis by Glucocorticoids. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2015. [PMID: 26215992 DOI: 10.1007/978-1-4939-2895-8_5] [Citation(s) in RCA: 383] [Impact Index Per Article: 42.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glucocorticoids are steroid hormones that regulate multiple aspects of glucose homeostasis. Glucocorticoids promote gluconeogenesis in liver, whereas in skeletal muscle and white adipose tissue they decrease glucose uptake and utilization by antagonizing insulin response. Therefore, excess glucocorticoid exposure causes hyperglycemia and insulin resistance. Glucocorticoids also regulate glycogen metabolism. In liver, glucocorticoids increase glycogen storage, whereas in skeletal muscle they play a permissive role for catecholamine-induced glycogenolysis and/or inhibit insulin-stimulated glycogen synthesis. Moreover, glucocorticoids modulate the function of pancreatic α and β cells to regulate the secretion of glucagon and insulin, two hormones that play a pivotal role in the regulation of blood glucose levels. Overall, the major glucocorticoid effect on glucose homeostasis is to preserve plasma glucose for brain during stress, as transiently raising blood glucose is important to promote maximal brain function. In this chapter we will discuss the current understanding of the mechanisms underlying different aspects of glucocorticoid-regulated mammalian glucose homeostasis.
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31
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Gong Z, Su K, Cui L, Tas E, Zhang T, Dong HH, Yakar S, Muzumdar RH. Central effects of humanin on hepatic triglyceride secretion. Am J Physiol Endocrinol Metab 2015; 309:E283-92. [PMID: 26058861 PMCID: PMC4525112 DOI: 10.1152/ajpendo.00043.2015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 06/04/2015] [Indexed: 02/06/2023]
Abstract
Humanin (HN) is an endogenous mitochondria-associated peptide that has been shown to protect against various Alzheimer's disease-associated insults, myocardial ischemia-reperfusion injury, and reactive oxygen species-induced cell death. We have shown previously that HN improves whole body glucose homeostasis by improving insulin sensitivity and increasing glucose-stimulated insulin secretion (GSIS) from the β-cells. Here, we report that intraperitoneal treatment with one of HN analogs, HNG, decreases body weight gain, visceral fat, and hepatic triglyceride (TG) accumulation in high-fat diet-fed mice. The decrease in hepatic TG accumulation is due to increased activity of hepatic microsomal triglyceride transfer protein (MTTP) and increased hepatic TG secretion. Both intravenous (iv) and intracerebroventricular (icv) infusion of HNG acutely increase TG secretion from the liver. Vagotomy blocks the effect on both iv and icv HNG on TG secretion, suggesting that the effects of HNG on hepatic TG flux are centrally mediated. Our data suggest that HN is a new player in central regulation of peripheral lipid metabolism.
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Affiliation(s)
- Zhenwei Gong
- Department of Pediatrics, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Kai Su
- Department of Pediatrics, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Lingguang Cui
- Department of Pediatrics, Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, New York; and
| | - Emir Tas
- Department of Pediatrics, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Ting Zhang
- Department of Pediatrics, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - H Henry Dong
- Department of Pediatrics, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Shoshana Yakar
- David B. Kriser Dental Center, Department of Basic Science and Craniofacial Biology, New York University College of Dentistry, New York, New York
| | - Radhika H Muzumdar
- Department of Pediatrics, Children's Hospital of Pittsburgh of the University of Pittsburgh Medical Center, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania;
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32
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Lucas CL, Zhang Y, Venida A, Wang Y, Hughes J, McElwee J, Butrick M, Matthews H, Price S, Biancalana M, Wang X, Richards M, Pozos T, Barlan I, Ozen A, Rao VK, Su HC, Lenardo MJ. Heterozygous splice mutation in PIK3R1 causes human immunodeficiency with lymphoproliferation due to dominant activation of PI3K. ACTA ACUST UNITED AC 2014; 211:2537-47. [PMID: 25488983 PMCID: PMC4267241 DOI: 10.1084/jem.20141759] [Citation(s) in RCA: 192] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Lucas et al. identify humans with a gain-of-function mutation in PIK3R1, encoding the p85α subunit of PI3K. The splice site mutation causes in-frame skipping of exon 11, resulting in altered p85α association with p110δ that stabilizes the catalytic subunit but fails to properly inhibit catalytic activity. The patients have immunodeficiency and lymphoproliferation with skewing of CD8+ T cells toward terminally differentiated and senescent effector cells that have shortened telomeres. Class IA phosphatidylinositol 3-kinases (PI3K), which generate PIP3 as a signal for cell growth and proliferation, exist as an intracellular complex of a catalytic subunit bound to a regulatory subunit. We and others have previously reported that heterozygous mutations in PIK3CD encoding the p110δ catalytic PI3K subunit cause a unique disorder termed p110δ-activating mutations causing senescent T cells, lymphadenopathy, and immunodeficiency (PASLI) disease. We report four patients from three families with a similar disease who harbor a recently reported heterozygous splice site mutation in PIK3R1, which encodes the p85α, p55α, and p50α regulatory PI3K subunits. These patients suffer from recurrent sinopulmonary infections and lymphoproliferation, exhibit hyperactive PI3K signaling, and have prominent expansion and skewing of peripheral blood CD8+ T cells toward terminally differentiated senescent effector cells with short telomeres. The PIK3R1 splice site mutation causes skipping of an exon, corresponding to loss of amino acid residues 434–475 in the inter-SH2 domain. The mutant p85α protein is expressed at low levels in patient cells and activates PI3K signaling when overexpressed in T cells from healthy subjects due to qualitative and quantitative binding changes in the p85α–p110δ complex and failure of the C-terminal region to properly inhibit p110δ catalytic activity.
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Affiliation(s)
- Carrie L Lucas
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Yu Zhang
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Anthony Venida
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Ying Wang
- Department of Clinical Immunology, Children's Hospital of Fudan University, Shanghai 200433, China
| | - Jason Hughes
- Merck Research Laboratories, Merck & Co, Boston, MA 02115
| | - Joshua McElwee
- Merck Research Laboratories, Merck & Co, Boston, MA 02115
| | - Morgan Butrick
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Helen Matthews
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Susan Price
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Matthew Biancalana
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Xiaochuan Wang
- Department of Clinical Immunology, Children's Hospital of Fudan University, Shanghai 200433, China
| | - Michael Richards
- Hematology/Oncology Clinic and Infectious Diseases and Immunology, Children's Hospitals and Clinics of Minnesota, Minneapolis, MN 55404
| | - Tamara Pozos
- Hematology/Oncology Clinic and Infectious Diseases and Immunology, Children's Hospitals and Clinics of Minnesota, Minneapolis, MN 55404
| | - Isil Barlan
- Pediatric Allergy and Immunology, Marmara University, Istanbul 34660, Turkey
| | - Ahmet Ozen
- Pediatric Allergy and Immunology, Marmara University, Istanbul 34660, Turkey
| | - V Koneti Rao
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Helen C Su
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
| | - Michael J Lenardo
- Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892 Molecular Development of the Immune System Section, Laboratory of Immunology; NIAID Clinical Genomics Program; Human Immunological Diseases Unit, Laboratory of Host Defenses; and Intramural Clinical Management and Operations Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892
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Murck H, Büttner M, Kircher T, Konrad C. Genetic, Molecular and Clinical Determinants for the Involvement of Aldosterone and Its Receptors in Major Depression. ACTA ACUST UNITED AC 2014; 128:17-25. [DOI: 10.1159/000368265] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Insulin receptor substrates are essential for the bioenergetic and hypertrophic response of the heart to exercise training. Mol Cell Biol 2014; 34:3450-60. [PMID: 25002528 DOI: 10.1128/mcb.00426-14] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Insulin and insulin-like growth factor 1 (IGF-1) receptor signaling pathways differentially modulate cardiac growth under resting conditions and following exercise training. These effects are mediated by insulin receptor substrate 1 (IRS1) and IRS2, which also differentially regulate resting cardiac mass. To determine the role of IRS isoforms in mediating the hypertrophic and metabolic adaptations of the heart to exercise training, we subjected mice with cardiomyocyte-specific deletion of either IRS1 (CIRS1 knockout [CIRS1KO] mice) or IRS2 (CIRS2KO mice) to swim training. CIRS1KO hearts were reduced in size under basal conditions, whereas CIRS2KO hearts exhibited hypertrophy. Following exercise swim training in CIRS1KO and CIRS2KO hearts, the hypertrophic response was equivalently attenuated, phosphoinositol 3-kinase (PI3K) activation was blunted, and prohypertrophic signaling intermediates, such as Akt and glycogen synthase kinase 3β (GSK3β), were dephosphorylated potentially on the basis of reduced Janus kinase-mediated inhibition of protein phosphatase 2a (PP2A). Exercise training increased peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) protein content, mitochondrial capacity, fatty acid oxidation, and glycogen synthesis in wild-type (WT) controls but not in IRS1- and IRS2-deficient hearts. PGC-1α protein content remained unchanged in CIRS1KO but decreased in CIRS2KO hearts. These results indicate that although IRS isoforms play divergent roles in the developmental regulation of cardiac size, these isoforms exhibit nonredundant roles in mediating the hypertrophic and metabolic response of the heart to exercise.
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Bunner AE, Chandrasekera PC, Barnard ND. Knockout mouse models of insulin signaling: Relevance past and future. World J Diabetes 2014; 5:146-159. [PMID: 24748928 PMCID: PMC3990311 DOI: 10.4239/wjd.v5.i2.146] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Revised: 01/03/2014] [Accepted: 02/20/2014] [Indexed: 02/05/2023] Open
Abstract
Insulin resistance is a hallmark of type 2 diabetes. In an effort to understand and treat this condition, researchers have used genetic manipulation of mice to uncover insulin signaling pathways and determine the effects of their perturbation. After decades of research, much has been learned, but the pathophysiology of insulin resistance in human diabetes remains controversial, and treating insulin resistance remains a challenge. This review will discuss limitations of mouse models lacking select insulin signaling molecule genes. In the most influential mouse models, glucose metabolism differs from that of humans at the cellular, organ, and whole-organism levels, and these differences limit the relevance and benefit of the mouse models both in terms of mechanistic investigations and therapeutic development. These differences are due partly to immutable differences in mouse and human biology, and partly to the failure of genetic modifications to produce an accurate model of human diabetes. Several factors often limit the mechanistic insights gained from experimental mice to the particular species and strain, including: developmental effects, unexpected metabolic adjustments, genetic background effects, and technical issues. We conclude that the limitations and weaknesses of genetically modified mouse models of insulin resistance underscore the need for redirection of research efforts toward methods that are more directly relevant to human physiology.
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Nicholas LM, Morrison JL, Rattanatray L, Ozanne SE, Kleemann DO, Walker SK, MacLaughlin SM, Zhang S, Martin-Gronert MS, McMillen IC. Differential effects of exposure to maternal obesity or maternal weight loss during the periconceptional period in the sheep on insulin signalling molecules in skeletal muscle of the offspring at 4 months of age. PLoS One 2013; 8:e84594. [PMID: 24386400 PMCID: PMC3873457 DOI: 10.1371/journal.pone.0084594] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2013] [Accepted: 11/25/2013] [Indexed: 11/19/2022] Open
Abstract
Exposure to maternal obesity before and/or throughout pregnancy may increase the risk of obesity and insulin resistance in the offspring in childhood and adult life, therefore, resulting in its transmission into subsequent generations. We have previously shown that exposure to maternal obesity around the time of conception alone resulted in increased adiposity in female lambs. Changes in the abundance of insulin signalling molecules in skeletal muscle and adipose tissue precede the development of insulin resistance and type 2 diabetes. It is not clear, however, whether exposure to maternal obesity results in insulin resistance in her offspring as a consequence of the impact of increased adiposity on skeletal muscle or as a consequence of the programming of specific changes in the abundance of insulin signalling molecules in this tissue. We have used an embryo transfer model in the sheep to investigate the effects of exposure to either maternal obesity or to weight loss in normal and obese mothers preceding and for one week after conception on the expression and abundance of insulin signalling molecules in muscle in the offspring. We found that exposure to maternal obesity resulted in lower muscle GLUT-4 and Ser 9 phospho-GSK3α and higher muscle GSK3α abundance in lambs when compared to lambs conceived in normally nourished ewes. Exposure to maternal weight loss in normal or obese mothers, however, resulted in lower muscle IRS1, PI3K, p110β, aPKCζ, Thr 642 phospho-AS160 and GLUT-4 abundance in the offspring. In conclusion, maternal obesity or weight loss around conception have each programmed specific changes on subsets of molecules in the insulin signalling, glucose transport and glycogen synthesis pathways in offspring. There is a need for a stronger evidence base to ensure that weight loss regimes in obese women seeking to become pregnant minimize the metabolic costs for the next generation.
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Affiliation(s)
- Lisa M. Nicholas
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Janna L. Morrison
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Leewen Rattanatray
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
- Discipline of Physiology, School of Molecular and Life Sciences, University of Adelaide, Adelaide, South Australia, Australia
| | - Susan E. Ozanne
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Dave O. Kleemann
- Turretfield Research Centre, South Australian Research and Development Institute, Rosedale, South Australia, Australia
| | - Simon K. Walker
- Turretfield Research Centre, South Australian Research and Development Institute, Rosedale, South Australia, Australia
| | - Severence M. MacLaughlin
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Song Zhang
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - Malgorzata S. Martin-Gronert
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, United Kingdom
| | - Isabella C. McMillen
- Sansom Institute for Health Research, School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
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Kuo T, Harris CA, Wang JC. Metabolic functions of glucocorticoid receptor in skeletal muscle. Mol Cell Endocrinol 2013; 380:79-88. [PMID: 23523565 PMCID: PMC4893778 DOI: 10.1016/j.mce.2013.03.003] [Citation(s) in RCA: 149] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Revised: 03/01/2013] [Accepted: 03/03/2013] [Indexed: 12/12/2022]
Abstract
Glucocorticoids (GCs) exert key metabolic influences on skeletal muscle. GCs increase protein degradation and decrease protein synthesis. The released amino acids are mobilized from skeletal muscle to liver, where they serve as substrates for hepatic gluconeogenesis. This metabolic response is critical for mammals' survival under stressful conditions, such as fasting and starvation. GCs suppress insulin-stimulated glucose uptake and utilization and glycogen synthesis, and play a permissive role for catecholamine-induced glycogenolysis, thus preserving the level of circulating glucose, the major energy source for the brain. However, chronic or excess exposure of GCs can induce muscle atrophy and insulin resistance. GCs convey their signal mainly through the intracellular glucocorticoid receptor (GR). While GR can act through different mechanisms, one of its major actions is to regulate the transcription of its primary target genes through genomic glucocorticoid response elements (GREs) by directly binding to DNA or tethering onto other DNA-binding transcription factors. These GR primary targets trigger physiological and pathological responses of GCs. Much progress has been made to understand how GCs regulate protein and glucose metabolism. In this review, we will discuss how GR primary target genes confer metabolic functions of GCs, and the mechanisms governing the transcriptional regulation of these targets. Comprehending these processes not only contributes to the fundamental understanding of mammalian physiology, but also will provide invaluable insight for improved GC therapeutics.
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Affiliation(s)
- Taiyi Kuo
- Department of Nutritional Science & Toxicology, University of California at Berkeley, Berkeley, CA 94720, United States
- Graduate Program of Endocrinology, University of California at Berkeley, Berkeley, CA 94720, United States
| | - Charles A. Harris
- Gladstone Institute of Cardiovascular Disease, San Francisco, CA 94158, United States
- Department of Medicine, University of California at San Francisco, San Francisco, CA 94143, United States
| | - Jen-Chywan Wang
- Department of Nutritional Science & Toxicology, University of California at Berkeley, Berkeley, CA 94720, United States
- Graduate Program of Endocrinology, University of California at Berkeley, Berkeley, CA 94720, United States
- Corresponding author. Address: Department of Nutritional Science and Toxicology, 315 Morgan Hall, University of California at Berkeley, Berkeley, CA 94720-3104, United States. Tel.: +1 510 643 1039. (J.-C. Wang)
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38
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Yoon MS, Zhang C, Sun Y, Schoenherr CJ, Chen J. Mechanistic target of rapamycin controls homeostasis of adipogenesis. J Lipid Res 2013; 54:2166-2173. [PMID: 23740969 DOI: 10.1194/jlr.m037705] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Signaling mediated by the mechanistic target of rapamycin (mTOR) is believed to play a critical and positive role in adipogenesis, based on pharmacological evidence and genetic manipulation of mTOR regulators and targets. However, there is no direct genetic evidence for an autonomous role of mTOR itself in preadipocyte differentiation. To seek such evidence, we employed a conditional knockdown approach to deplete mTOR in preadipocytes. Surprisingly, while knockdown of S6K1, a target of mTOR, impairs 3T3-L1 preadipocyte differentiation, reduction of mTOR levels leads to increased differentiation. This enhanced adipogenesis requires the remaining mTOR activity, as mTOR inhibitors abolish differentiation in the mTOR knockdown cells. We also found that mTOR knockdown elevates the levels of CCAAT/enhancer-binding protein α (C/EBPα) and peroxisome proliferator-activated receptor γ (PPARγ). Furthermore, partial reduction of mTOR levels alleviates inhibition of Akt by mTORC1 via IRS1, while at the same time maintaining its positive input through mTORC1 into the adipogenic program. The greater sensitivity of the IRS1-Akt pathway to mTOR levels provides a mechanism that explains the net outcome of enhanced adipogenesis through PPARγ upon mTOR knockdown. Our observations reveal an unexpected role of mTOR in suppressing adipogenesis and suggest that mTOR governs the homeostasis of the adipogenic process by modulating multiple signaling pathways.
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Affiliation(s)
- Mee-Sup Yoon
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Chongben Zhang
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Yuting Sun
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Christopher J Schoenherr
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Jie Chen
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
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FBXL2- and PTPL1-mediated degradation of p110-free p85β regulatory subunit controls the PI(3)K signalling cascade. Nat Cell Biol 2013; 15:472-80. [PMID: 23604317 DOI: 10.1038/ncb2731] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2012] [Accepted: 03/13/2013] [Indexed: 12/11/2022]
Abstract
F-box proteins are the substrate-recognition subunits of SCF (Skp1/Cul1/F-box protein) ubiquitin ligase complexes. Purification of the F-box protein FBXL2 identified the PI(3)K regulatory subunit p85β and tyrosine phosphatase PTPL1 as interacting proteins. FBXL2 interacts with the pool of p85β that is free of p110 PI(3)K catalytic subunits and targets this pool for ubiquitylation and subsequent proteasomal degradation. FBXL2-mediated degradation of p85β is dependent on the integrity of its CaaX motif. Whereas most SCF substrates require phosphorylation to interact with their F-box proteins, phosphorylation of p85β on Tyr 655, which is adjacent to the degron, inhibits p85β binding to FBXL2. Dephosphorylation of phospho-Tyr-655 by PTPL1 stimulates p85β binding to and degradation through FBXL2. Finally, defects in the FBXL2-mediated degradation of p85β inhibit the binding of p110 subunits to IRS1, attenuate the PI(3)K signalling cascade and promote autophagy. We propose that FBXL2 and PTPL1 suppress p85β levels, preventing the inhibition of PI(3)K by an excess of free p85 that could compete with p85-p110 heterodimers for IRS1.
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Roberts CK, Hevener AL, Barnard RJ. Metabolic syndrome and insulin resistance: underlying causes and modification by exercise training. Compr Physiol 2013. [PMID: 23720280 DOI: 10.1002/cphy.c110062.metabolic] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
Metabolic syndrome (MS) is a collection of cardiometabolic risk factors that includes obesity, insulin resistance, hypertension, and dyslipidemia. Although there has been significant debate regarding the criteria and concept of the syndrome, this clustering of risk factors is unequivocally linked to an increased risk of developing type 2 diabetes and cardiovascular disease. Regardless of the true definition, based on current population estimates, nearly 100 million have MS. It is often characterized by insulin resistance, which some have suggested is a major underpinning link between physical inactivity and MS. The purpose of this review is to: (i) provide an overview of the history, causes and clinical aspects of MS, (ii) review the molecular mechanisms of insulin action and the causes of insulin resistance, and (iii) discuss the epidemiological and intervention data on the effects of exercise on MS and insulin sensitivity.
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Affiliation(s)
- Christian K Roberts
- Exercise and Metabolic Disease Research Laboratory, Translational Sciences Section, School of Nursing, University of California at Los Angeles, Los Angeles, California, USA.
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41
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McCurdy CE, Schenk S, Holliday MJ, Philp A, Houck JA, Patsouris D, MacLean PS, Majka SM, Klemm DJ, Friedman JE. Attenuated Pik3r1 expression prevents insulin resistance and adipose tissue macrophage accumulation in diet-induced obese mice. Diabetes 2012; 61:2495-505. [PMID: 22698915 PMCID: PMC3447911 DOI: 10.2337/db11-1433] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Obese white adipose tissue (AT) is characterized by large-scale infiltration of proinflammatory macrophages, in parallel with systemic insulin resistance; however, the cellular stimulus that initiates this signaling cascade and chemokine release is still unknown. The objective of this study was to determine the role of the phosphoinositide 3-kinase (PI3K) regulatory subunits on AT macrophage (ATM) infiltration in obesity. Here, we find that the Pik3r1 regulatory subunits (i.e., p85α/p55α/p50α) are highly induced in AT from high-fat diet-fed obese mice, concurrent with insulin resistance. Global heterozygous deletion of the Pik3r1 regulatory subunits (αHZ), but not knockout of Pik3r2 (p85β), preserves whole-body, AT, and skeletal muscle insulin sensitivity, despite severe obesity. Moreover, ATM accumulation, proinflammatory gene expression, and ex vivo chemokine secretion in obese αHZ mice are markedly reduced despite endoplasmic reticulum (ER) stress, hypoxia, adipocyte hypertrophy, and Jun NH(2)-terminal kinase activation. Furthermore, bone marrow transplant studies reveal that these improvements in obese αHZ mice are independent of reduced Pik3r1 expression in the hematopoietic compartment. Taken together, these studies demonstrate that Pik3r1 expression plays a critical role in mediating AT insulin sensitivity and, more so, suggest that reduced PI3K activity is a key step in the initiation and propagation of the inflammatory response in obese AT.
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Affiliation(s)
- Carrie E McCurdy
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA.
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42
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Utermark T, Rao T, Cheng H, Wang Q, Lee SH, Wang ZC, Iglehart JD, Roberts TM, Muller WJ, Zhao JJ. The p110α and p110β isoforms of PI3K play divergent roles in mammary gland development and tumorigenesis. Genes Dev 2012; 26:1573-86. [PMID: 22802530 DOI: 10.1101/gad.191973.112] [Citation(s) in RCA: 109] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Class Ia phosphatidylinositol 3 kinase (PI3K) is required for oncogenic receptor-mediated transformation; however, the individual roles of the two commonly expressed class Ia PI3K isoforms in oncogenic receptor signaling have not been elucidated in vivo. Here, we show that genetic ablation of p110α blocks tumor formation in both polyoma middle T antigen (MT) and HER2/Neu transgenic models of breast cancer. Surprisingly, p110β ablation results in both increased ductal branching and tumorigenesis. Biochemical analyses suggest a competition model in which the less active p110β competes with the more active p110α for receptor binding sites, thereby modulating the level of PI3K activity associated with activated receptors. Our findings demonstrate a novel p110β-based regulatory role in receptor-mediated PI3K activity and identify p110α as an important target for treatment of HER2-positive disease.
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Affiliation(s)
- Tamara Utermark
- Department of Cancer Biology, Dana-Farber Cancer Institute, Boston, Massachusetts 02215, USA
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Tiano JP, Mauvais-Jarvis F. Molecular mechanisms of estrogen receptors' suppression of lipogenesis in pancreatic β-cells. Endocrinology 2012; 153:2997-3005. [PMID: 22564979 PMCID: PMC3380304 DOI: 10.1210/en.2011-1980] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The gonadal steroid, 17β-estradiol (E2), suppresses pancreatic islet fatty acid and glycerolipid synthesis and prevents β-cell failure in rodent models of type 2 diabetes. β-Cell estrogen receptors (ER) mediate these actions by suppressing the expression and enzymatic activity of fatty acid synthase (FAS). Here, we explored the mechanism of FAS suppression. We show that E2, and pharmacological agonists for ERα, ERβ, and the G protein-coupled ER, suppress mRNA and protein expression of the transcriptional regulators of FAS, namely, sterol regulatory element-binding protein 1c (SREBP1c) and carbohydrate response element binding protein (ChREBP) in insulin-secreting INS-1 cells. ER suppress SREBP1c and ChREBP mRNA and protein expression via an extranuclear localization. Using two mouse lines with pancreas-specific null deletion of either ERα or the signal transducer and activator of transcription 3 (STAT3), we show that ERα activation in vivo reduces SREBP1c and ChREBP mRNA expression via a direct islet action involving STAT3 activation. The master regulators of lipogenesis, liver X receptor (LXR) α and β, transcriptionally up-regulate SREBP1c and ChREBP. We find that activation of ERα, ERβ, and G protein-coupled ER suppresses LXR's mRNA expression in INS-1 cells. We also observe that activation of ERα in mouse islets in vivo suppresses LXR mRNA in a STAT3-dependent manner. Finally, we show that E2 also activates and uses AMP-activated protein kinase in INS-1 cells to suppress SREBP1c protein expression. This study identifies extranuclear ER pathways involving STAT3 and AMP-activated protein kinase in the genetic control of lipogenesis with therapeutic implications to protect β-cells in type 2 diabetes.
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Affiliation(s)
- Joseph P Tiano
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, 303 East Chicago Avenue, Chicago, Illinois 60611, USA
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Genome-wide analysis of glucocorticoid receptor-binding sites in myotubes identifies gene networks modulating insulin signaling. Proc Natl Acad Sci U S A 2012; 109:11160-5. [PMID: 22733784 DOI: 10.1073/pnas.1111334109] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Glucocorticoids elicit a variety of biological responses in skeletal muscle, including inhibiting protein synthesis and insulin-stimulated glucose uptake and promoting proteolysis. Thus, excess or chronic glucocorticoid exposure leads to muscle atrophy and insulin resistance. Glucocorticoids propagate their signal mainly through glucocorticoid receptors (GR), which, upon binding to ligands, translocate to the nucleus and bind to genomic glucocorticoid response elements to regulate the transcription of nearby genes. Using a combination of chromatin immunoprecipitation sequencing and microarray analysis, we identified 173 genes in mouse C2C12 myotubes. The mouse genome contains GR-binding regions in or near these genes, and gene expression is regulated by glucocorticoids. Eight of these genes encode proteins known to regulate distinct signaling events in insulin/insulin-like growth factor 1 pathways. We found that overexpression of p85α, one of these eight genes, caused a decrease in C2C12 myotube diameters, mimicking the effect of glucocorticoids. Moreover, reducing p85α expression by RNA interference in C2C12 myotubes significantly compromised the ability of glucocorticoids to inhibit Akt and p70 S6 kinase activity and reduced glucocorticoid induction of insulin receptor substrate 1 phosphorylation at serine 307. This phosphorylation is associated with insulin resistance. Furthermore, decreasing p85α expression abolished glucocorticoid inhibition of protein synthesis and compromised glucocorticoid-induced reduction of cell diameters in C2C12 myotubes. Finally, a glucocorticoid response element was identified in the p85α GR-binding regions. In summary, our studies identified GR-regulated transcriptional networks in myotubes and showed that p85α plays a critical role in glucocorticoid-induced insulin resistance and muscle atrophy in C2C12 myotubes.
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González-Rodríguez A, Más-Gutierrez JA, Mirasierra M, Fernandez-Pérez A, Lee YJ, Ko HJ, Kim JK, Romanos E, Carrascosa JM, Ros M, Vallejo M, Rondinone CM, Valverde AM. Essential role of protein tyrosine phosphatase 1B in obesity-induced inflammation and peripheral insulin resistance during aging. Aging Cell 2012; 11:284-96. [PMID: 22221695 DOI: 10.1111/j.1474-9726.2011.00786.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Protein tyrosine phosphatase 1B (PTP1B) is a negative regulator of insulin signaling and a therapeutic target for type 2 diabetes (T2DM). In this study, we have evaluated the role of PTP1B in the development of aging-associated obesity, inflammation, and peripheral insulin resistance by assessing metabolic parameters at 3 and 16 months in PTP1B(-/-) mice maintained on mixed genetic background (C57Bl/6J × 129Sv/J). Whereas fat mass and adipocyte size were increased in wild-type control mice at 16 months, these parameters did not change with aging in PTP1B(-/-) mice. Increased levels of pro-inflammatory cytokines, crown-like structures, and hypoxia-inducible factor (HIF)-1α were observed only in adipose tissue from 16-month-old wild-type mice. Similarly, islet hyperplasia and hyperinsulinemia were observed in wild-type mice with aging-associated obesity, but not in PTP1B(-/-) animals. Leanness in 16-month-old PTP1B(-/-) mice was associated with increased energy expenditure. Whole-body insulin sensitivity decreased in 16-month-old control mice; however, studies with the hyperinsulinemic-euglycemic clamp revealed that PTP1B deficiency prevented this obesity-related decreased peripheral insulin sensitivity. At a molecular level, PTP1B expression and enzymatic activity were up-regulated in liver and muscle of 16-month-old wild-type mice as were the activation of stress kinases and the expression of p53. Conversely, insulin receptor-mediated Akt/Foxo1 signaling was attenuated in these aged control mice. Collectively, these data implicate PTP1B in the development of inflammation and insulin resistance associated with obesity during aging and suggest that inhibition of this phosphatase by therapeutic strategies might protect against age-dependent T2DM.
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Vijayakumar A, Wu Y, Sun H, Li X, Jeddy Z, Liu C, Schwartz GJ, Yakar S, LeRoith D. Targeted loss of GHR signaling in mouse skeletal muscle protects against high-fat diet-induced metabolic deterioration. Diabetes 2012; 61:94-103. [PMID: 22187377 PMCID: PMC3237669 DOI: 10.2337/db11-0814] [Citation(s) in RCA: 61] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Growth hormone (GH) exerts diverse tissue-specific metabolic effects that are not revealed by global alteration of GH action. To study the direct metabolic effects of GH in the muscle, we specifically inactivated the growth hormone receptor (ghr) gene in postnatal mouse skeletal muscle using the Cre/loxP system (mGHRKO model). The metabolic state of the mGHRKO mice was characterized under lean and obese states. High-fat diet feeding in the mGHRKO mice was associated with reduced adiposity, improved insulin sensitivity, lower systemic inflammation, decreased muscle and hepatic triglyceride content, and greater energy expenditure compared with control mice. The obese mGHRKO mice also had an increased respiratory exchange ratio, suggesting increased carbohydrate utilization. GH-regulated suppressor of cytokine signaling-2 (socs2) expression was decreased in obese mGHRKO mice. Interestingly, muscles of both lean and obese mGHRKO mice demonstrated a higher interleukin-15 and lower myostatin expression relative to controls, indicating a possible mechanism whereby GHR signaling in muscle could affect liver and adipose tissue function. Thus, our study implicates skeletal muscle GHR signaling in mediating insulin resistance in obesity and, more importantly, reveals a novel role of muscle GHR signaling in facilitating cross-talk between muscle and other metabolic tissues.
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Affiliation(s)
- Archana Vijayakumar
- Division of Endocrinology, Diabetes, and Bone Diseases, Department of Medicine, Mount Sinai School of Medicine, New York, New York
| | - YingJie Wu
- Division of Endocrinology, Diabetes, and Bone Diseases, Department of Medicine, Mount Sinai School of Medicine, New York, New York
| | - Hui Sun
- Division of Endocrinology, Diabetes, and Bone Diseases, Department of Medicine, Mount Sinai School of Medicine, New York, New York
| | - Xiaosong Li
- Departments of Medicine and Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Zuha Jeddy
- Division of Endocrinology, Diabetes, and Bone Diseases, Department of Medicine, Mount Sinai School of Medicine, New York, New York
| | - Chengyu Liu
- Transgenic Core Facility, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland
| | - Gary J. Schwartz
- Departments of Medicine and Neuroscience, Albert Einstein College of Medicine, Bronx, New York
| | - Shoshana Yakar
- Division of Endocrinology, Diabetes, and Bone Diseases, Department of Medicine, Mount Sinai School of Medicine, New York, New York
| | - Derek LeRoith
- Division of Endocrinology, Diabetes, and Bone Diseases, Department of Medicine, Mount Sinai School of Medicine, New York, New York
- Corresponding authors: Derek LeRoith, , and Shoshana Yakar,
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Schenk S, McCurdy CE, Philp A, Chen MZ, Holliday MJ, Bandyopadhyay GK, Osborn O, Baar K, Olefsky JM. Sirt1 enhances skeletal muscle insulin sensitivity in mice during caloric restriction. J Clin Invest 2011; 121:4281-8. [PMID: 21985785 DOI: 10.1172/jci58554] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Accepted: 09/07/2011] [Indexed: 01/08/2023] Open
Abstract
Skeletal muscle insulin resistance is a key component of the etiology of type 2 diabetes. Caloric restriction (CR) enhances the sensitivity of skeletal muscle to insulin. However, the molecular signals within skeletal muscle linking CR to improved insulin action remain largely unknown. Recently, the mammalian ortholog of Sir2, sirtuin 1 (Sirt1), has been identified as a potential transducer of perturbations in cellular energy flux into subsequent metabolic adaptations, including modulation of skeletal muscle insulin action. Here, we have demonstrated that CR increases Sirt1 deacetylase activity in skeletal muscle in mice, in parallel with enhanced insulin-stimulated phosphoinositide 3-kinase (PI3K) signaling and glucose uptake. These adaptations in skeletal muscle insulin action were completely abrogated in mice lacking Sirt1 deacetylase activity. Mechanistically, Sirt1 was found to be required for the deacetylation and inactivation of the transcription factor Stat3 during CR, which resulted in decreased gene and protein expression of the p55α/p50α subunits of PI3K, thereby promoting more efficient PI3K signaling during insulin stimulation. Thus, these data demonstrate that Sirt1 is an integral signaling node in skeletal muscle linking CR to improved insulin action, primarily via modulation of PI3K signaling.
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Affiliation(s)
- Simon Schenk
- Division of Endocrinology and Metabolism, Department of Medicine, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0673, USA
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Kulkarni SS, Karlsson HKR, Szekeres F, Chibalin AV, Krook A, Zierath JR. Suppression of 5'-nucleotidase enzymes promotes AMP-activated protein kinase (AMPK) phosphorylation and metabolism in human and mouse skeletal muscle. J Biol Chem 2011; 286:34567-74. [PMID: 21873433 PMCID: PMC3186409 DOI: 10.1074/jbc.m111.268292] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2011] [Revised: 08/18/2011] [Indexed: 11/06/2022] Open
Abstract
The 5'-nucleotidase (NT5) family of enzyme dephosphorylates non-cyclic nucleoside monophosphates to produce nucleosides and inorganic phosphates. We hypothesized that gene silencing of NT5 enzymes to increase the intracellular availability of AMP would increase AMP-activated protein kinase (AMPK) activity and metabolism. We determined the role of cytosolic NT5 in metabolic responses linked to the development of insulin resistance in obesity and type 2 diabetes. Using siRNA to silence NT5C2 expression in cultured human myotubes, we observed a 2-fold increase in the AMP/ATP ratio, a 2.4-fold increase in AMPK phosphorylation (Thr(172)), and a 2.8-fold increase in acetyl-CoA carboxylase phosphorylation (Ser(79)) (p < 0.05). siRNA silencing of NT5C2 expression increased palmitate oxidation by 2-fold in the absence and by 8-fold in the presence of 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside. This was paralleled by an increase in glucose transport and a decrease in glucose oxidation, incorporation into glycogen, and lactate release from NT5C2-depleted myotubes. Gene silencing of NT5C1A by shRNA injection and electroporation in mouse tibialis anterior muscle reduced protein content (60%; p < 0.05) and increased phosphorylation of AMPK (60%; p < 0.05) and acetyl-CoA carboxylase (50%; p < 0.05) and glucose uptake (20%; p < 0.05). Endogenous expression of NT5C enzymes inhibited basal lipid oxidation and glucose transport in skeletal muscle. Reduction of 5'-nucleotidase expression or activity may promote metabolic flexibility in type 2 diabetes.
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Affiliation(s)
- Sameer S. Kulkarni
- From the Departments of Molecular Medicine and Surgery and Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Håkan K. R. Karlsson
- From the Departments of Molecular Medicine and Surgery and Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Ferenc Szekeres
- From the Departments of Molecular Medicine and Surgery and Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Alexander V. Chibalin
- From the Departments of Molecular Medicine and Surgery and Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Anna Krook
- From the Departments of Molecular Medicine and Surgery and Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden
| | - Juleen R. Zierath
- From the Departments of Molecular Medicine and Surgery and Physiology and Pharmacology, Karolinska Institutet, S-171 77 Stockholm, Sweden
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Tiano JP, Delghingaro-Augusto V, Le May C, Liu S, Kaw MK, Khuder SS, Latour MG, Bhatt SA, Korach KS, Najjar SM, Prentki M, Mauvais-Jarvis F. Estrogen receptor activation reduces lipid synthesis in pancreatic islets and prevents β cell failure in rodent models of type 2 diabetes. J Clin Invest 2011; 121:3331-42. [PMID: 21747171 DOI: 10.1172/jci44564] [Citation(s) in RCA: 136] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Accepted: 05/18/2011] [Indexed: 12/11/2022] Open
Abstract
The failure of pancreatic β cells to adapt to an increasing demand for insulin is the major mechanism by which patients progress from insulin resistance to type 2 diabetes (T2D) and is thought to be related to dysfunctional lipid homeostasis within those cells. In multiple animal models of diabetes, females demonstrate relative protection from β cell failure. We previously found that the hormone 17β-estradiol (E2) in part mediates this benefit. Here, we show that treating male Zucker diabetic fatty (ZDF) rats with E2 suppressed synthesis and accumulation of fatty acids and glycerolipids in islets and protected against β cell failure. The antilipogenic actions of E2 were recapitulated by pharmacological activation of estrogen receptor α (ERα) or ERβ in a rat β cell line and in cultured ZDF rat, mouse, and human islets. Pancreas-specific null deletion of ERα in mice (PERα-/-) prevented reduction of lipid synthesis by E2 via a direct action in islets, and PERα-/- mice were predisposed to islet lipid accumulation and β cell dysfunction in response to feeding with a high-fat diet. ER activation inhibited β cell lipid synthesis by suppressing the expression (and activity) of fatty acid synthase via a nonclassical pathway dependent on activated Stat3. Accordingly, pancreas-specific deletion of Stat3 in mice curtailed ER-mediated suppression of lipid synthesis. These data suggest that extranuclear ERs may be promising therapeutic targets to prevent β cell failure in T2D.
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Affiliation(s)
- Joseph P Tiano
- Department of Medicine, Division of Endocrinology, Metabolism and Molecular Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, USA
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Huang J, Zhang L, Greshock J, Colligon TA, Wang Y, Ward R, Katsaros D, Lassus H, Butzow R, Godwin AK, Testa JR, Nathanson KL, Gimotty PA, Coukos G, Weber BL, Degenhardt Y. Frequent genetic abnormalities of the PI3K/AKT pathway in primary ovarian cancer predict patient outcome. Genes Chromosomes Cancer 2011. [PMID: 21563232 DOI: 10.1002/gcc.20883] [] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Identification and characterization of underlying genetic aberrations could facilitate diagnosis and treatment of ovarian cancer. Copy number analysis using array Comparative Genomic Hybridization (aCGH) on 93 primary ovarian tumors identified PI3K/AKT pathway as the most frequently altered cancer related pathway. Furthermore, survival analyses to correlate gene copy number and mutation data with patient outcome showed that copy number gains of PIK3CA, PIK3CB, and PIK3R4 in these tumors were associated with decreased survival. To confirm these findings at the protein level, immunohistochemistry (IHC) for PIK3CA product p110α and p-Akt was performed on tissue microarrays from 522 independent serous ovarian cancers. Overexpression of either of these two proteins was found to be associated with decreased survival. Multivariant analysis from these samples further showed that overexpression of p-AKT and/or p110α is an independent prognostic factor for these tumors. siRNAs targeting altered PI3K/AKT pathway genes inhibited proliferation and induced apoptosis in ovarian cancer cell lines. In addition, the effect of the siRNAs in different cell lines seemed to correlate with the particular genetic alterations that the cell line carries. These results strongly support the utilization of PI3K pathway inhibitors in ovarian cancer. They also suggest identifying the specific component in the PI3K pathway that is genetically altered has the potential to help select the most effective therapy. Both mutation as well as copy number changes can be used as predictive markers for this purpose.
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Affiliation(s)
- Jia Huang
- Department of Biology, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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