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Gupta I, Gaykalova DA. Unveiling the role of PIK3R1 in cancer: A comprehensive review of regulatory signaling and therapeutic implications. Semin Cancer Biol 2024; 106-107:58-86. [PMID: 39197810 DOI: 10.1016/j.semcancer.2024.08.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 07/11/2024] [Accepted: 08/20/2024] [Indexed: 09/01/2024]
Abstract
Phosphoinositide 3-kinase (PI3K) is responsible for phosphorylating phosphoinositides to generate secondary signaling molecules crucial for regulating various cellular processes, including cell growth, survival, and metabolism. The PI3K is a heterodimeric enzyme complex comprising of a catalytic subunit (p110α, p110β, or p110δ) and a regulatory subunit (p85). The binding of the regulatory subunit, p85, with the catalytic subunit, p110, forms an integral component of the PI3K enzyme. PIK3R1 (phosphoinositide-3-kinase regulatory subunit 1) belongs to class IA of the PI3K family. PIK3R1 exhibits structural complexity due to alternative splicing, giving rise to distinct isoforms, prominently p85α and p55α. While the primary p85α isoform comprises multiple domains, including Src homology 3 (SH3) domains, a Breakpoint Cluster Region Homology (BH) domain, and Src homology 2 (SH2) domains (iSH2 and nSH2), the shorter isoform, p55α, lacks certain domains present in p85α. In this review, we will highlight the intricate regulatory mechanisms governing PI3K signaling along with the impact of PIK3R1 alterations on cellular processes. We will further delve into the clinical significance of PIK3R1 mutations in various cancer types and their implications for prognosis and treatment outcomes. Additionally, we will discuss the evolving landscape of targeted therapies aimed at modulating PI3K-associated pathways. Overall, this review will provide insights into the dynamic interplay of PIK3R1 in cancer, fostering advancements in precision medicine and the development of targeted interventions.
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Affiliation(s)
- Ishita Gupta
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Otorhinolaryngology-Head and Neck Surgery, Marlene & Stewart Greenebaum Comprehensive Cancer Center, University of Maryland Medical Center, Baltimore, MD, USA
| | - Daria A Gaykalova
- Institute for Genome Sciences, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Otorhinolaryngology-Head and Neck Surgery, Marlene & Stewart Greenebaum Comprehensive Cancer Center, University of Maryland Medical Center, Baltimore, MD, USA; Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, USA.
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2
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Li H, Wen X, Ren Y, Fan Z, Zhang J, He G, Fu L. Targeting PI3K family with small-molecule inhibitors in cancer therapy: current clinical status and future directions. Mol Cancer 2024; 23:164. [PMID: 39127670 DOI: 10.1186/s12943-024-02072-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2024] [Accepted: 07/25/2024] [Indexed: 08/12/2024] Open
Abstract
The Phosphatidylinositol-3-kinase (PI3K) family is well-known to comprise three classes of intracellular enzymes. Class I PI3Ks primarily function in signaling by responding to cell surface receptor stimulation, while class II and III are more involved in membrane transport. Under normal physiological conditions, the PI3K signaling network orchestrates cell growth, division, migration and survival. Aberrant activation of the PI3K signaling pathway disrupts cellular activity and metabolism, often marking the onset of cancer. Currently, the Food and Drug Administration (FDA) has approved the clinical use of five class I PI3K inhibitors. These small-molecule inhibitors, which exhibit varying selectivity for different class I PI3K family members, are primarily used in the treatment of breast cancer and hematologic malignancies. Therefore, the development of novel class I PI3K inhibitors has been a prominent research focus in the field of oncology, aiming to enhance potential therapeutic selectivity and effectiveness. In this review, we summarize the specific structures of PI3Ks and their functional roles in cancer progression. Additionally, we critically evaluate small molecule inhibitors that target class I PI3K, with a particular focus on their clinical applications in cancer treatment. Moreover, we aim to analyze therapeutic approaches for different types of cancers marked by aberrant PI3K activation and to identify potential molecular targets amenable to intervention with small-molecule inhibitors. Ultimately, we propose future directions for the development of therapeutic strategies that optimize cancer treatment outcomes by modulating the PI3K family.
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Affiliation(s)
- Hongyao Li
- Institute of Precision Drug Innovation and Cancer Center, the Second Hospital of Dalian Medical University, Dalian, 116023, China
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
- Department of Dermatology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Sichuan University, Chengdu, 610041, China
| | - Xiang Wen
- Department of Dermatology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Sichuan University, Chengdu, 610041, China
| | - Yueting Ren
- Department of Dermatology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Sichuan University, Chengdu, 610041, China
- Department of Brain Science, Faculty of Medicine, Imperial College, London, SW72AZ, UK
| | - Zhichao Fan
- Institute of Precision Drug Innovation and Cancer Center, the Second Hospital of Dalian Medical University, Dalian, 116023, China
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China
- Department of Dermatology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Sichuan University, Chengdu, 610041, China
| | - Jin Zhang
- School of Pharmaceutical Sciences of Medical School, Shenzhen University, Shenzhen, 518000, China.
| | - Gu He
- Department of Dermatology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Sichuan University, Chengdu, 610041, China.
| | - Leilei Fu
- Institute of Precision Drug Innovation and Cancer Center, the Second Hospital of Dalian Medical University, Dalian, 116023, China.
- Sichuan Engineering Research Center for Biomimetic Synthesis of Natural Drugs, School of Life Science and Engineering, Southwest Jiaotong University, Chengdu, 610031, China.
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3
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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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4
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Thapa N, Chen M, Cryns VL, Anderson R. A p85 isoform switch enhances PI3K activation on endosomes by a MAP4- and PI3P-dependent mechanism. Cell Rep 2024; 43:114119. [PMID: 38630589 PMCID: PMC11380499 DOI: 10.1016/j.celrep.2024.114119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Revised: 02/21/2024] [Accepted: 03/29/2024] [Indexed: 04/19/2024] Open
Abstract
Phosphatidylinositol 3-kinase α (PI3Kα) is a heterodimer of p110α catalytic and p85 adaptor subunits that is activated by agonist-stimulated receptor tyrosine kinases. Although p85α recruits p110α to activated receptors on membranes, p85α loss, which occurs commonly in cancer, paradoxically promotes agonist-stimulated PI3K/Akt signaling. p110α localizes to microtubules via microtubule-associated protein 4 (MAP4), facilitating its interaction with activated receptor kinases on endosomes to initiate PI3K/Akt signaling. Here, we demonstrate that in response to agonist stimulation and p85α knockdown, the residual p110α, coupled predominantly to p85β, exhibits enhanced recruitment with receptor tyrosine kinases to endosomes. Moreover, the p110α C2 domain binds PI3-phosphate, and this interaction is also required to recruit p110α to endosomes and for PI3K/Akt signaling. Stable knockdown of p85α, which mimics the reduced p85α levels observed in cancer, enhances cell growth and tumorsphere formation, and these effects are abrogated by MAP4 or p85β knockdown, underscoring their role in the tumor-promoting activity of p85α loss.
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Affiliation(s)
- Narendra Thapa
- School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA
| | - Mo Chen
- School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA
| | - Vincent L Cryns
- Department of Medicine, School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA
| | - Richard Anderson
- School of Medicine and Public Health, University of Wisconsin-Madison, 1111 Highland Avenue, Madison, WI 53705, USA.
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5
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Correa Pinto Junior D, Canal Delgado I, Yang H, Clemenceau A, Corvelo A, Narzisi G, Musunuri R, Meyer Berger J, Hendricks LE, Tokumura K, Luo N, Li H, Oury F, Ducy P, Yadav VK, Li X, Karsenty G. Osteocalcin of maternal and embryonic origins synergize to establish homeostasis in offspring. EMBO Rep 2024; 25:593-615. [PMID: 38228788 PMCID: PMC10897216 DOI: 10.1038/s44319-023-00031-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 11/24/2023] [Accepted: 12/01/2023] [Indexed: 01/18/2024] Open
Abstract
Many physiological osteocalcin-regulated functions are affected in adult offspring of mothers experiencing unhealthy pregnancy. Furthermore, osteocalcin signaling during gestation influences cognition and adrenal steroidogenesis in adult mice. Together these observations suggest that osteocalcin may broadly function during pregnancy to determine organismal homeostasis in adult mammals. To test this hypothesis, we analyzed in unchallenged wildtype and Osteocalcin-deficient, newborn and adult mice of various genotypes and origin maintained on different genetic backgrounds, the functions of osteocalcin in the pancreas, liver and testes and their molecular underpinnings. This analysis revealed that providing mothers are Osteocalcin-deficient, Osteocalcin haploinsufficiency in embryos hampers insulin secretion, liver gluconeogenesis, glucose homeostasis, testes steroidogenesis in adult offspring; inhibits cell proliferation in developing pancreatic islets and testes; and disrupts distinct programs of gene expression in these organs and in the brain. This study indicates that osteocalcin exerts dominant functions in most organs it influences. Furthermore, through their synergistic regulation of multiple physiological functions, osteocalcin of maternal and embryonic origins contributes to the establishment and maintenance of organismal homeostasis in newborn and adult offspring.
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Affiliation(s)
- Danilo Correa Pinto Junior
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Isabella Canal Delgado
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Haiyang Yang
- Guangdong Provincial Key Laboratory of Brain Connectome, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China
| | - Alisson Clemenceau
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | | | | | | | - Julian Meyer Berger
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Lauren E Hendricks
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Kazuya Tokumura
- Department of Bioactive Molecules, Pharmacology, Gifu Pharmaceutical University, Gifu, Japan
| | - Na Luo
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA
| | - Hongchao Li
- Guangdong Provincial Key Laboratory of Brain Connectome, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China
| | - Franck Oury
- INSERM U1151, Institut Necker Enfants-Malades (INEM), Université Paris Descartes-Sorbonne, Paris Cité, Paris, France.
| | - Patricia Ducy
- Department of Pathology and Cell Biology, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
| | - Vijay K Yadav
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
| | - Xiang Li
- Guangdong Provincial Key Laboratory of Brain Connectome, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen Institute of Advanced Technology, Chinese Academy of Sciences, 518055, Shenzhen, China.
| | - Gerard Karsenty
- Department of Genetics and Development, Vagelos College of Physicians and Surgeons, Columbia University, New York, NY, USA.
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6
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Kim CW, Lee JM, Park SW. Divergent roles of the regulatory subunits of class IA PI3K. Front Endocrinol (Lausanne) 2024; 14:1152579. [PMID: 38317714 PMCID: PMC10839044 DOI: 10.3389/fendo.2023.1152579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Accepted: 12/11/2023] [Indexed: 02/07/2024] Open
Abstract
The regulatory subunit of phosphatidylinositol 3-kinase (PI3K), known as p85, is a critical component in the insulin signaling pathway. Extensive research has shed light on the diverse roles played by the two isoforms of p85, namely p85α and p85β. The gene pik3r1 encodes p85α and its variants, p55α and p50α, while pik3r2 encodes p85β. These isoforms exhibit various activities depending on tissue types, nutrient availability, and cellular stoichiometry. Whole-body or liver-specific deletion of pik3r1 have shown to display increased insulin sensitivity and improved glucose homeostasis; however, skeletal muscle-specific deletion of p85α does not exhibit any significant effects on glucose homeostasis. On the other hand, whole-body deletion of pik3r2 shows improved insulin sensitivity with no significant impact on glucose tolerance. Meanwhile, liver-specific double knockout of pik3r1 and pik3r2 leads to reduced insulin sensitivity and glucose tolerance. In the context of obesity, upregulation of hepatic p85α or p85β has been shown to improve glucose homeostasis. However, hepatic overexpression of p85α in the absence of p50α and p55α results in increased insulin resistance in obese mice. p85α and p85β have distinctive roles in cancer development. p85α acts as a tumor suppressor, but p85β promotes tumor progression. In the immune system, p85α facilitates B cell development, while p85β regulates T cell differentiation and maturation. This review provides a comprehensive overview of the distinct functions attributed to p85α and p85β, highlighting their significance in various physiological processes, including insulin signaling, cancer development, and immune system regulation.
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Affiliation(s)
- Cho-Won Kim
- Division of Endocrinology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
| | - Junsik M. Lee
- Division of Endocrinology, Boston Children’s Hospital, Boston, MA, United States
| | - Sang Won Park
- Division of Endocrinology, Boston Children’s Hospital, Boston, MA, United States
- Department of Pediatrics, Harvard Medical School, Boston, MA, United States
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7
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Oh J, Riek AE, Bauerle KT, Dusso A, McNerney KP, Barve RA, Darwech I, Sprague JE, Moynihan C, Zhang RM, Kutz G, Wang T, Xing X, Li D, Mrad M, Wigge NM, Castelblanco E, Collin A, Bambouskova M, Head RD, Sands MS, Bernal-Mizrachi C. Embryonic vitamin D deficiency programs hematopoietic stem cells to induce type 2 diabetes. Nat Commun 2023; 14:3278. [PMID: 37311757 PMCID: PMC10264405 DOI: 10.1038/s41467-023-38849-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 05/19/2023] [Indexed: 06/15/2023] Open
Abstract
Environmental factors may alter the fetal genome to cause metabolic diseases. It is unknown whether embryonic immune cell programming impacts the risk of type 2 diabetes in later life. We demonstrate that transplantation of fetal hematopoietic stem cells (HSCs) made vitamin D deficient in utero induce diabetes in vitamin D-sufficient mice. Vitamin D deficiency epigenetically suppresses Jarid2 expression and activates the Mef2/PGC1a pathway in HSCs, which persists in recipient bone marrow, resulting in adipose macrophage infiltration. These macrophages secrete miR106-5p, which promotes adipose insulin resistance by repressing PIK3 catalytic and regulatory subunits and down-regulating AKT signaling. Vitamin D-deficient monocytes from human cord blood have comparable Jarid2/Mef2/PGC1a expression changes and secrete miR-106b-5p, causing adipocyte insulin resistance. These findings suggest that vitamin D deficiency during development has epigenetic consequences impacting the systemic metabolic milieu.
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Affiliation(s)
- Jisu Oh
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Amy E Riek
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Kevin T Bauerle
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Medicine, VA Medical Center, St. Louis, MO, USA
| | - Adriana Dusso
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Kyle P McNerney
- Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, USA
| | - Ruteja A Barve
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Isra Darwech
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Clare Moynihan
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Rong M Zhang
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Greta Kutz
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Ting Wang
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Xiaoyun Xing
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Daofeng Li
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Marguerite Mrad
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Nicholas M Wigge
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | | | - Alejandro Collin
- Instituto de Investigaciones en Ciencias de la Salud (INICSA), CONICET, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Monika Bambouskova
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
| | - Richard D Head
- Department of Genetics, Washington University School of Medicine, St. Louis, MO, USA
| | - Mark S Sands
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA
| | - Carlos Bernal-Mizrachi
- Department of Medicine, Washington University School of Medicine, St. Louis, MO, USA.
- Department of Medicine, VA Medical Center, St. Louis, MO, USA.
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO, USA.
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8
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Guilherme A, Rowland LA, Wang H, Czech MP. The adipocyte supersystem of insulin and cAMP signaling. Trends Cell Biol 2023; 33:340-354. [PMID: 35989245 PMCID: PMC10339226 DOI: 10.1016/j.tcb.2022.07.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/27/2022] [Accepted: 07/28/2022] [Indexed: 01/28/2023]
Abstract
Adipose tissue signals to brain, liver, and muscles to control whole body metabolism through secreted lipid and protein factors as well as neurotransmission, but the mechanisms involved are incompletely understood. Adipocytes sequester triglyceride (TG) in fed conditions stimulated by insulin, while in fasting catecholamines trigger TG hydrolysis, releasing glycerol and fatty acids (FAs). These antagonistic hormone actions result in part from insulin's ability to inhibit cAMP levels generated through such G-protein-coupled receptors as catecholamine-activated β-adrenergic receptors. Consistent with these antagonistic signaling modes, acute actions of catecholamines cause insulin resistance. Yet, paradoxically, chronically activating adipocytes by catecholamines cause increased glucose tolerance, as does insulin. Recent results have helped to unravel this conundrum by revealing enhanced complexities of these hormones' signaling networks, including identification of unexpected common signaling nodes between these canonically antagonistic hormones.
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Affiliation(s)
- Adilson Guilherme
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA.
| | - Leslie A Rowland
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Hui Wang
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA
| | - Michael P Czech
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA 01605, USA.
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9
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Chakraborty G, Nandakumar S, Hirani R, Nguyen B, Stopsack KH, Kreitzer C, Rajanala SH, Ghale R, Mazzu YZ, Pillarsetty NVK, Mary Lee GS, Scher HI, Morris MJ, Traina T, Razavi P, Abida W, Durack JC, Solomon SB, Vander Heiden MG, Mucci LA, Wibmer AG, Schultz N, Kantoff PW. The Impact of PIK3R1 Mutations and Insulin-PI3K-Glycolytic Pathway Regulation in Prostate Cancer. Clin Cancer Res 2022; 28:3603-3617. [PMID: 35670774 PMCID: PMC9438279 DOI: 10.1158/1078-0432.ccr-21-4272] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 03/07/2022] [Accepted: 06/03/2022] [Indexed: 11/16/2022]
Abstract
PURPOSE Oncogenic alterations of the PI3K/AKT pathway occur in >40% of patients with metastatic castration-resistant prostate cancer, predominantly via PTEN loss. The significance of other PI3K pathway components in prostate cancer is largely unknown. EXPERIMENTAL DESIGN Patients in this study underwent tumor sequencing using the MSK-IMPACT clinical assay to capture single-nucleotide variants, insertions, and deletions; copy-number alterations; and structural rearrangements, or were profiled through The Cancer Genome Atlas. The association between PIK3R1 alteration/expression and survival was evaluated using univariable and multivariable Cox proportional-hazards regression models. We used the siRNA-based knockdown of PIK3R1 for functional studies. FDG-PET/CT examinations were performed with a hybrid positron emission tomography (PET)/CT scanner for some prostate cancer patients in the MSK-IMPACT cohort. RESULTS Analyzing 1,417 human prostate cancers, we found a significant enrichment of PIK3R1 alterations in metastatic cancers compared with primary cancers. PIK3R1 alterations or reduced mRNA expression tended to be associated with worse clinical outcomes in prostate cancer, particularly in primary disease, as well as in breast, gastric, and several other cancers. In prostate cancer cell lines, PIK3R1 knockdown resulted in increased cell proliferation and AKT activity, including insulin-stimulated AKT activity. In cell lines and organoids, PIK3R1 loss/mutation was associated with increased sensitivity to AKT inhibitors. PIK3R1-altered patient prostate tumors had increased uptake of the glucose analogue 18F-fluorodeoxyglucose in PET imaging, suggesting increased glycolysis. CONCLUSIONS Our findings describe a novel genomic feature in metastatic prostate cancer and suggest that PIK3R1 alteration may be a key event for insulin-PI3K-glycolytic pathway regulation in prostate cancer.
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Affiliation(s)
- Goutam Chakraborty
- Department of Urology, Icahn School of Medicine at Mount Sinai, New York, NY
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Subhiksha Nandakumar
- Center for Molecular Oncology, Memorial Sloan Kettering Cancer Center, New York, NY
- Human Oncology & Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Rahim Hirani
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Bastien Nguyen
- Center for Molecular Oncology, Memorial Sloan Kettering Cancer Center, New York, NY
- Human Oncology & Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Konrad H. Stopsack
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Christoph Kreitzer
- Center for Molecular Oncology, Memorial Sloan Kettering Cancer Center, New York, NY
- Human Oncology & Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | | | - Romina Ghale
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Ying Z. Mazzu
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
| | | | - Gwo-Shu Mary Lee
- Department of Medicine, Dana-Farber Cancer Institute, Boston, MA
| | - Howard I. Scher
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
- Biomarker Development Program, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Michael J. Morris
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Tiffany Traina
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Pedram Razavi
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Wassim Abida
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Jeremy C. Durack
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Stephen B. Solomon
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Matthew G. Vander Heiden
- Koch Institute for Integrative Cancer Research and the Department of Biology at Massachusetts Institute of Technology, Cambridge, MA
| | - Lorelei A. Mucci
- Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA
| | - Andreas G. Wibmer
- Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Nikolaus Schultz
- Center for Molecular Oncology, Memorial Sloan Kettering Cancer Center, New York, NY
- Human Oncology & Pathogenesis Program, Memorial Sloan Kettering Cancer Center, New York, NY
- Department of Epidemiology & Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Philip W. Kantoff
- Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, NY
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10
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Yoshida K, Matsuoka T, Kobatake Y, Takashima S, Nishii N. Quantitative assessment of muscle mass and gene expression analysis in dogs with glucocorticoid-induced muscle atrophy. J Vet Med Sci 2022; 84:275-281. [PMID: 34980764 PMCID: PMC8920714 DOI: 10.1292/jvms.21-0325] [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] [Indexed: 11/22/2022] Open
Abstract
The present study aimed to quantitatively evaluate muscle mass and gene expression in
dogs with glucocorticoid-induced muscle atrophy. Five healthy beagles received oral
prednisolone for 4 weeks (1 mg/kg/day), and muscle mass was then evaluated via computed
tomography. Histological and gene expression analyses were performed using biopsy samples
from the biceps femoris before and after prednisolone administration. The cross-sectional
area of the third lumbar paraspinal and mid-femoral muscles significantly decreased after
glucocorticoid administration (from 27.5 ± 1.9 to 22.6 ± 2.0 cm2 and from 55.1
± 4.7 to 50.7 ± 4.1 cm2, respectively; P<0.01). The fast-
and slow-twitch muscle fibers were both atrophied (from 2,779 ± 369 to 1,581 ± 207
μm2 and from 2,871 ± 211 to 1,971 ± 169 μm2, respectively;
P<0.05). The expression of the growth factor receptor-bound protein
10 (GRB10) significantly increased after prednisolone administration
(P<0.05). Because GRB10 suppresses insulin
signaling and the subsequent mammalian target of rapamycin complex 1 activity, increased
expression of GRB10 may have resulted in a decrease in protein anabolism.
Taken together, 1 mg/kg/day oral prednisolone for 4 weeks induced significant muscle
atrophy in dogs, and GRB10 might participate in the pathology of
glucocorticoid-induced muscle atrophy in canines.
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Affiliation(s)
- Kei Yoshida
- Joint Department of Veterinary Medicine, The United Graduate School of Veterinary Science, Gifu University
| | - Toshio Matsuoka
- Joint Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University.,Blanco Animal Hospital
| | - Yui Kobatake
- Joint Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University
| | - Satoshi Takashima
- Joint Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University
| | - Naohito Nishii
- Joint Department of Veterinary Medicine, The United Graduate School of Veterinary Science, Gifu University.,Joint Department of Veterinary Medicine, Faculty of Applied Biological Science, Gifu University
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11
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Pei J, Wang B, Wang D. Current Studies on Molecular Mechanisms of Insulin Resistance. J Diabetes Res 2022; 2022:1863429. [PMID: 36589630 PMCID: PMC9803571 DOI: 10.1155/2022/1863429] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 06/06/2022] [Accepted: 12/12/2022] [Indexed: 12/24/2022] Open
Abstract
Diabetes is a metabolic disease that raises the risk of microvascular and neurological disorders. Insensitivity to insulin is a characteristic of type II diabetes, which accounts for 85-90 percent of all diabetic patients. The fundamental molecular factor of insulin resistance may be impaired cell signal transduction mediated by the insulin receptor (IR). Several cell-signaling proteins, including IR, insulin receptor substrate (IRS), and phosphatidylinositol 3-kinase (PI3K), have been recognized as being important in the impaired insulin signaling pathway since they are associated with a large number of proteins that are strictly regulated and interact with other signaling pathways. Many studies have found a correlation between IR alternative splicing, IRS gene polymorphism, the complicated regulatory function of IRS serine/threonine phosphorylation, and the negative regulatory role of p85 in insulin resistance and diabetes mellitus. This review brings up-to-date knowledge of the roles of signaling proteins in insulin resistance in order to aid in the discovery of prospective targets for insulin resistance treatment.
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Affiliation(s)
- Jinli Pei
- Shandong Cancer Hospital and Institute, Shandong First Medical University and Shandong Academy of Medical Sciences, Jinan, Shandong, China
| | - Baochun Wang
- The First Department of Gastrointestinal Surgery, Hainan General Hospital, Haikou, Hainan 570228, China
| | - Dayong Wang
- Laboratory of Biopharmaceuticals and Molecular Pharmacology, School of Pharmaceutical Sciences, Hainan University, Hainan 570228, China
- State Key Laboratory of Tropical Biological Resources of the Ministry of Education of China, Hainan University, Hainan 570228, China
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12
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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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13
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Lee JM, Liu R, Park SW. The regulatory subunits of PI3K, p85α and p85β, differentially affect BRD7-mediated regulation of insulin signaling. J Mol Cell Biol 2021; 13:889-901. [PMID: 34751372 PMCID: PMC8800525 DOI: 10.1093/jmcb/mjab073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 09/15/2021] [Accepted: 09/24/2021] [Indexed: 11/12/2022] Open
Abstract
Bromodomain-containing protein 7 (BRD7) has been shown to interact with the regulatory subunit of phosphatidylinositol 3-kinase (PI3K), p85, in the insulin signaling pathway. Here, we show that upregulation of hepatic BRD7 improves glucose homeostasis even in the absence of either p85 isoform, p85α or p85β. However, BRD7 leads to differential activation of downstream effector proteins in the insulin signaling pathway depending on which isoform of p85 is present. In the presence of only p85α, BRD7 overexpression increases phosphorylation of insulin receptor (IR) upon insulin stimulation, without increasing the recruitment of p85 to IR substrate. Overexpression of BRD7 also increases activation of Akt in response to insulin, but does not affect basal phosphorylation levels of Akt. Meanwhile, the phosphorylation of glycogen synthase kinase 3β (GSK3β) is increased by overexpression of BRD7. On the other hand, in the presence of only p85β, BRD7 overexpression does not affect phosphorylation levels of IR, and Akt phosphorylation is not affected by insulin stimulation following BRD7 upregulation. However, BRD7 overexpression leads to increased basal phosphorylation levels of Akt and GSK3β. These data demonstrate that BRD7’s action on glucose homeostasis does not require the presence of both p85 isoforms, and p85α and p85β have unique roles in insulin signaling in the liver.
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Affiliation(s)
- Junsik M Lee
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115 USA
| | - Renyan Liu
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115 USA
| | - Sang Won Park
- Division of Endocrinology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115 USA
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14
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Nguyen T, Deenick EK, Tangye SG. Phosphatidylinositol 3-kinase signaling and immune regulation: insights into disease pathogenesis and clinical implications. Expert Rev Clin Immunol 2021; 17:905-914. [PMID: 34157234 DOI: 10.1080/1744666x.2021.1945443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
INTRODUCTION Phosphatidylinositol 3-kinase (PI3K) is a lipid kinase that plays a fundamental role in cell survival, metabolism, proliferation and differentiation. Thus, balanced PI3K signalling is critical for multiple aspects of human health. The discovery that germline variants in genes in the PI3K pathway caused inborn errors of immunity highlighted the non-redundant role of these signalling proteins in the human immune system. The subsequent identification and characterisation of >300 individuals with a novel immune dysregulatory disorder, termed activated PI3K-delta syndrome (APDS), has reinforced the status of PI3K as a key pathway regulating immune function. Studies of APDS have demonstrated that dysregulated PI3K function is disruptive for immune cell development, activation, differentiation, effector function and self-tolerance, which are all important in supporting effective, long-term immune responses. AREAS COVERED In this review, we recount recent findings regarding humans with germline variants in PI3K genes and discuss the underlying cellular and molecular pathologies, with a focus on implications for therapy in APDS patients. EXPERT OPINION Modulating PI3K immune cell signalling by offers opportunities for therapeutic interventions in settings of immunodeficiency, autoimmunity and malignancy, but also highlights potential adverse events that may result from overt pharmacological or intrinsic inhibition of PI3K function.
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Affiliation(s)
- Tina Nguyen
- Immunity & Inflammation Theme, Garvan Institute of Medical Research, Darlinghurst, Australia.,St Vincent's Clinical Clinical School, University of NSW, Kensington, NSW, Australia
| | - Elissa K Deenick
- Immunity & Inflammation Theme, Garvan Institute of Medical Research, Darlinghurst, Australia.,St Vincent's Clinical Clinical School, University of NSW, Kensington, NSW, Australia
| | - Stuart G Tangye
- Immunity & Inflammation Theme, Garvan Institute of Medical Research, Darlinghurst, Australia.,St Vincent's Clinical Clinical School, University of NSW, Kensington, NSW, Australia
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15
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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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16
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Research on saponin active compounds of Tuchao Baibiandouren for the treatment of type-2 diabetes based on UHPLC-Q-Exactive Orbitrap MS and network pharmacology. DIGITAL CHINESE MEDICINE 2021. [DOI: 10.1016/j.dcmed.2021.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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17
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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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18
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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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19
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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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20
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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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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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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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Gao L, Tang H, Zeng Q, Tang T, Chen M, Pu P. The anti-insulin resistance effect of scutellarin may be related to antioxidant stress and AMPKα activation in diabetic mice. Obes Res Clin Pract 2020; 14:368-374. [PMID: 32631803 DOI: 10.1016/j.orcp.2020.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2020] [Revised: 06/10/2020] [Accepted: 06/23/2020] [Indexed: 12/25/2022]
Abstract
AIMS Scutellarein (Sc), a natural compound and an active ingredient of Erigeronbrevis-capus (Vant.), shows anti-obesity, anti-inflammation and lipid-lowering properties in our previous study. However, no previous in vivo and vitro has been conducted to assess the effects of Sc in insulin resistance (IR). This study investigated the effects of Sc on IR and oxidative stress and explored the underlying mechanisms of action in vivo and vitro. MATERIAL AND METHOD A well-established mouse model of IR, induced by high-fat diet (HFD) feeding, was applied in this study. The effects of Sc were evaluated on obesity, glycometabolism disorder and oxidative stress. The anti-IR effect was assessed using blood glucose, serum insulin, HOMA index, intraperitoneal glucose tolerance tests (IPGTT), intraperitoneal insulin tolerance tests (IPITT), and glucose-regulating enzyme activity. The insulin signaling pathways and AMPKα expressions were tested by Western blot. The primary culture of hepatocytes was prepared and used for confirming the above signaling pathways. RESULTS Obesity, IR and oxidative stress developed in HFD mice. Administration of Sc at a dose of 50mg/kg for 16 weeks effectively attenuated these changes. Further studies revealed the antagonistic effect of Sc on IR was a result of the activation of the insulin signaling pathway and AMPKα. The primary hepatocyte test, stimulated by high glucose, further confirmed that SC exerts anti-IR through the above signaling pathway and key protein. CONCLUSION These results suggested that Sc possesses not only an important novel anti-IR effect but also an anti-oxidative stress effect. These favorable effects were causally associated with weight loss and the improved glycometabolism. The underlying mechanisms might associated with the activation of the insulin signaling pathway and AMPKα. Our study promotes the understanding of the pharmacological actions of Sc, and plays a role for Sc in the effective treatment of diabetes mellitus.
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Affiliation(s)
- Lingyun Gao
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Heng Tang
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Qingfu Zeng
- Department of Vascular Surgery, The Second Affiliated Hospital of Nanchang University, People's Republic of China
| | - Ting Tang
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Ming Chen
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China
| | - Peng Pu
- Department of Cardiology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, People's Republic of China.
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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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25
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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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26
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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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27
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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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28
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Giacco A, Delli Paoli G, Senese R, Cioffi F, Silvestri E, Moreno M, Ruoppolo M, Caterino M, Costanzo M, Lombardi A, Goglia F, Lanni A, de Lange P. The saturation degree of fatty acids and their derived acylcarnitines determines the direct effect of metabolically active thyroid hormones on insulin sensitivity in skeletal muscle cells. FASEB J 2018; 33:1811-1823. [PMID: 30204501 DOI: 10.1096/fj.201800724r] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Using differentiated rat L6 cells, we studied the direct effect of 3,5,3'-triiodo-l-thyronine (T3) and 3,5-diiodo-l-thyronine (T2) on the response to insulin in presence of fatty acids with a varying degree of saturation. We found that T3 and T2 both invert the response to insulin by modulating Akt Ser473 phosphorylation in the presence of palmitate and oleate. Both hormones prevented palmitate-induced insulin resistance, whereas increased insulin sensitivity in the presence of oleate was reduced, with normalization to (or, in the case of T3, even below) control levels. Both hormones effectively reduced intracellular acylcarnitine concentrations. Interestingly, insulin sensitization was lowered by incubation of the myotubes with relevant concentrations of palmitoylcarnitines (C16) and increased by oleylcarnitines and linoleylcarnitines (C18:1 and C18:2, respectively). The efficiency of mitochondrial respiration decreased in the order palmitate-oleate-linoleate; in the presence of palmitate, only T3 increased ATP synthesis-independent cellular respiration and mitochondrial respiratory complex activities. Both hormones modulated gene expression and enzyme activities related to insulin sensitivity, glucose metabolism, and lipid handling. Although T2 and T3 differentially regulated the expression of relevant genes involved in glucose metabolism, they equally stimulated related metabolic activities. T2 and T3 differentially modulated mitochondrial fatty acid uptake and oxidation in the presence of each fatty acid. The results show that T2 and T3 both invert the fatty acid-induced response to insulin but through different mechanisms, and that the outcome depends on the degree of saturation of the fatty acids and their derived acylcarnitines.-Giacco, A., delli Paoli, G., Senese, R., Cioffi, F., Silvestri, E., Moreno, M., Ruoppolo, M., Caterino, M., Costanzo, M., Lombardi, A., Goglia, F., Lanni, A., de Lange, P. The saturation degree of fatty acids and their derived acylcarnitines determines the direct effect of metabolically active thyroid hormones on insulin sensitivity in skeletal muscle cells.
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Affiliation(s)
- Antonia Giacco
- Dipartimento di Scienze e Tecnologie, Università degli Studi del Sannio, Benevento, Italy
| | - Giuseppe Delli Paoli
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania Luigi Vanvitelli, Caserta, Italy
| | - Rosalba Senese
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania Luigi Vanvitelli, Caserta, Italy
| | - Federica Cioffi
- Dipartimento di Scienze e Tecnologie, Università degli Studi del Sannio, Benevento, Italy
| | - Elena Silvestri
- Dipartimento di Scienze e Tecnologie, Università degli Studi del Sannio, Benevento, Italy
| | - Maria Moreno
- Dipartimento di Scienze e Tecnologie, Università degli Studi del Sannio, Benevento, Italy
| | - Margherita Ruoppolo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Naples, Italy.,Ceinge-Biotecnologie Avanzate, Naples, Italy.,Divulgazione Scientifica Multidisciplinare per la Sostenibilità Ricerca, Formazione, Cultura (DiSciMuS RCF), Naples, Italy
| | - Marianna Caterino
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Naples, Italy.,Ceinge-Biotecnologie Avanzate, Naples, Italy.,Divulgazione Scientifica Multidisciplinare per la Sostenibilità Ricerca, Formazione, Cultura (DiSciMuS RCF), Naples, Italy
| | - Michele Costanzo
- Dipartimento di Medicina Molecolare e Biotecnologie Mediche, Università degli Studi di Napoli Federico II, Naples, Italy.,Ceinge-Biotecnologie Avanzate, Naples, Italy.,Divulgazione Scientifica Multidisciplinare per la Sostenibilità Ricerca, Formazione, Cultura (DiSciMuS RCF), Naples, Italy
| | - Assunta Lombardi
- Dipartimento di Biologia, Università degli Studi di Napoli Federico II, Naples, Italy
| | - Fernando Goglia
- Dipartimento di Scienze e Tecnologie, Università degli Studi del Sannio, Benevento, Italy
| | - Antonia Lanni
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania Luigi Vanvitelli, Caserta, Italy
| | - Pieter de Lange
- Dipartimento di Scienze e Tecnologie Ambientali, Biologiche e Farmaceutiche, Università degli Studi della Campania Luigi Vanvitelli, Caserta, Italy
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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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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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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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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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34
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Tups A, Benzler J, Sergi D, Ladyman SR, Williams LM. Central Regulation of Glucose Homeostasis. Compr Physiol 2017; 7:741-764. [DOI: 10.1002/cphy.c160015] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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35
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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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36
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TOUSKOVA V, KLOUCKOVA J, DUROVCOVA V, LACINOVA Z, KAVALKOVA P, TRACHTA P, KOSAK M, MRAZ M, HALUZIKOVA D, HANA V, MAREK J, KRSEK M, HALUZIK M. The Possible Role of mRNA Expression Changes of GH/IGF-1/Insulin Axis Components in Subcutaneous Adipose Tissue in Metabolic Disturbances of Patients With Acromegaly. Physiol Res 2016; 65:493-503. [DOI: 10.33549/physiolres.933244] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
We explored the effect of chronically elevated circulating levels of growth hormone (GH)/insulin-like-growth-factor-1 (IGF-1) on mRNA expression of GH/IGF-1/insulin axis components and p85alpha subunit of phosphoinositide-3-kinase (p85alpha) in subcutaneous adipose tissue (SCAT) of patients with active acromegaly and compared these findings with healthy control subjects in order to find its possible relationships with insulin resistance and body composition changes. Acromegaly group had significantly decreased percentage of truncal and whole body fat and increased homeostasis model assessment-insulin resistance (HOMA-IR). In SCAT, patients with acromegaly had significantly increased IGF-1 and IGF-binding protein-3 (IGFBP-3) expression that both positively correlated with serum GH. P85alpha expression in SCAT did not differ from control group. IGF-1 and IGFBP-3 expression in SCAT were not independently associated with percentage of truncal and whole body fat or with HOMA-IR while IGFBP-3 expression in SCAT was an independent predictor of insulin receptor as well as of p85alpha expression in SCAT. Our data suggest that GH overproduction in acromegaly group increases IGF-1 and IGFBP-3 expression in SCAT while it does not affect SCAT p85alpha expression. Increased IGF-1 or IGFBP-3 in SCAT of acromegaly group do not appear to contribute to systemic differences in insulin sensitivity but may have local regulatory effects in SCAT of patients with acromegaly.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | | | - M. HALUZIK
- Institute of Endocrinology, Prague, Czech Republic
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37
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Kruse M, Keyhani-Nejad F, Isken F, Nitz B, Kretschmer A, Reischl E, de las Heras Gala T, Osterhoff MA, Grallert H, Pfeiffer AFH. High-Fat Diet During Mouse Pregnancy and Lactation Targets GIP-Regulated Metabolic Pathways in Adult Male Offspring. Diabetes 2016; 65:574-84. [PMID: 26631738 DOI: 10.2337/db15-0478] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Accepted: 11/20/2015] [Indexed: 11/13/2022]
Abstract
Maternal obesity is a worldwide problem associated with increased risk of metabolic diseases in the offspring. Genetic deletion of the gastric inhibitory polypeptide (GIP) receptor (GIPR) prevents high-fat diet (HFD)-induced obesity in mice due to specific changes in energy and fat cell metabolism. We investigated whether GIP-associated pathways may be targeted by fetal programming and mimicked the situation by exposing pregnant mice to control or HFD during pregnancy (intrauterine [IU]) and lactation (L). Male wild-type (WT) and Gipr(-/-) offspring received control chow until 25 weeks of age followed by 20 weeks of HFD. Gipr(-/-) offspring of mice exposed to HFD during IU/L became insulin resistant and obese and exhibited increased adipose tissue inflammation and decreased peripheral tissue substrate utilization after being reintroduced to HFD, similar to WT mice on regular chow during IU/L. They showed decreased hypothalamic insulin sensitivity compared with Gipr(-/-) mice on control diet during IU/L. DNA methylation analysis revealed increased methylation of CpG dinucleotides and differential transcription factor binding of promoter regions of genes involved in lipid oxidation in the muscle of Gipr(-/-) offspring on HFD during IU/L, which were inversely correlated with gene expression levels. Our data identify GIP-regulated metabolic pathways that are targeted by fetal programming.
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Affiliation(s)
- Michael Kruse
- Department of Clinical Nutrition, German Institute of Human Nutrition, Nuthetal, Germany Department of Endocrinology and Metabolic Diseases, Charité-University of Medicine, Berlin, Germany German Center for Diabetes Research, Neuherberg, Germany
| | - Farnaz Keyhani-Nejad
- Department of Clinical Nutrition, German Institute of Human Nutrition, Nuthetal, Germany Department of Endocrinology and Metabolic Diseases, Charité-University of Medicine, Berlin, Germany German Center for Diabetes Research, Neuherberg, Germany
| | - Frank Isken
- Department of Clinical Nutrition, German Institute of Human Nutrition, Nuthetal, Germany Department of Endocrinology and Metabolic Diseases, Charité-University of Medicine, Berlin, Germany German Center for Diabetes Research, Neuherberg, Germany
| | - Barbara Nitz
- German Center for Diabetes Research, Neuherberg, Germany Research Unit of Molecular Epidemiology, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany Institute of Epidemiology II, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany
| | - Anja Kretschmer
- Research Unit of Molecular Epidemiology, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany Institute of Epidemiology II, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany
| | - Eva Reischl
- Research Unit of Molecular Epidemiology, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany Institute of Epidemiology II, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany
| | - Tonia de las Heras Gala
- Institute of Epidemiology II, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany
| | - Martin A Osterhoff
- Department of Clinical Nutrition, German Institute of Human Nutrition, Nuthetal, Germany Department of Endocrinology and Metabolic Diseases, Charité-University of Medicine, Berlin, Germany German Center for Diabetes Research, Neuherberg, Germany
| | - Harald Grallert
- German Center for Diabetes Research, Neuherberg, Germany Research Unit of Molecular Epidemiology, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany Institute of Epidemiology II, German Research Center for Environmental Health, Helmholtz Zentrum München, Neuherberg, Germany
| | - Andreas F H Pfeiffer
- Department of Clinical Nutrition, German Institute of Human Nutrition, Nuthetal, Germany Department of Endocrinology and Metabolic Diseases, Charité-University of Medicine, Berlin, Germany German Center for Diabetes Research, Neuherberg, Germany
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38
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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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39
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Abstract
A continuous supply of glucose is necessary to ensure proper function and survival of all organs. Plasma glucose levels are thus maintained in a narrow range around 5 mM, which is considered the physiological set point. Glucose homeostasis is controlled primarily by the liver, fat, and skeletal muscle. Following a meal, most glucose disposals occur in the skeletal muscle, whereas fasting plasma glucose levels are determined primarily by glucose output from the liver. The balance between the utilization and production of glucose is primarily maintained at equilibrium by two opposing hormones, insulin and glucagon. In response to an elevation in plasma glucose and amino acids (after consumption of a meal), insulin is released from the beta cells of the islets of Langerhans in the pancreas. When plasma glucose falls (during fasting or exercise), glucagon is secreted by α cells, which surround the beta cells in the pancreas. Both cell types are extremely sensitive to glucose concentrations, can regulate hormone synthesis, and are released in response to small changes in plasma glucose levels. At the same time, insulin serves as the major physiological anabolic agent, promoting the synthesis and storage of glucose, lipids, and proteins and inhibiting their degradation and release back into the circulation. This chapter will focus mainly on signal transduction mechanisms by which insulin exerts its plethora of effects in liver, muscle, and fat cells, focusing on those pathways that are crucial in the control of glucose and lipid homeostasis.
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Affiliation(s)
- Alan R Saltiel
- Life Sciences Institute, University of Michigan, AnnArbor, MI, USA.
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40
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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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41
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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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42
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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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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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Roberts CK, Hevener AL, Barnard RJ. Metabolic syndrome and insulin resistance: underlying causes and modification by exercise training. Compr Physiol 2013; 3:1-58. [PMID: 23720280 DOI: 10.1002/cphy.c110062] [Citation(s) in RCA: 270] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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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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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46
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Nicholas LM, Rattanatray L, MacLaughlin SM, Ozanne SE, Kleemann DO, Walker SK, Morrison JL, Zhang S, Muhlhäusler BS, Martin-Gronert MS, McMillen IC. Differential effects of maternal obesity and weight loss in the periconceptional period on the epigenetic regulation of hepatic insulin-signaling pathways in the offspring. FASEB J 2013; 27:3786-96. [PMID: 23729590 DOI: 10.1096/fj.13-227918] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Our aim was to determine the effect of exposure to maternal obesity or to maternal weight loss around conception on the programming of hepatic insulin signaling in the offspring. We used an embryo transfer model in sheep to investigate the effects of exposure to either maternal obesity or to weight loss in normal and obese mothers preceding and for 1 wk after conception on the expression of hepatic insulin-signaling and gluconeogenic factors and key miRNAs involved in insulin signaling in the offspring. We found that exposure to maternal obesity resulted in increased hepatic miR-29b (P<0.05), miR-103 (P<0.01), and miR-107 (P<0.05) expression, a decrease in IR (P<0.05), phopsho-Akt (P<0.01), and phospho-FoxO1 (P<0.01) abundance, and a paradoxical decrease in 11βHSD1 (P<0.05), PEPCK-C (P<0.01), and PEPCK-M (P<0.05) expression in lambs. These changes were ablated by a period of moderate dietary restriction imposed during the periconceptional period. Maternal dietary restriction alone also resulted in decreased abundance of a separate subset of hepatic insulin-signaling molecules, namely, IRS1 (P<0.05), PDK1 (P<0.01), phospho-PDK1 (P<0.05), and aPKCζ (P<0.05) and in decreased PEPCK-C (P<0.01) and G6Pase (P<0.01) expression in the lamb. Our findings highlight the sensitivity of the epigenome to maternal nutrition around conception and the need for dietary interventions that maximize metabolic benefits and minimize 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
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Yoo YM. Melatonin-mediated insulin synthesis during endoplasmic reticulum stress involves HuD expression in rat insulinoma INS-1E cells. J Pineal Res 2013; 55:207-20. [PMID: 23711134 DOI: 10.1111/jpi.12064] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 04/26/2013] [Indexed: 01/12/2023]
Abstract
In this study, we investigated how melatonin mediates insulin synthesis through endoplasmic reticulum (ER) via HuD expression in rat insulinoma INS-1E cells. Under ER stress condition (thapsigargin with/without melatonin, tunicamycin with/without melatonin), phosphorylation of AMP-activated protein kinase (p-AMPK) was significantly increased when compared with only with/without melatonin (control/melatonin). Insulin receptor substrate (IRS) two protein was significantly reduced under conditions of ER stress when compared with control/melatonin, but no expression of IRS1 protein was observed. In thapsigargin treatment, melatonin (10, 50 μm) increased IRS2 protein expression in a dose-dependent manner. p-Akt (Ser473) expression significantly decreased under ER stress condition prior to control/melatonin. Melatonin (10, 50 μm) significantly reduced nuclear and cellular p85α expressions in a dose-dependent manner when compared with only thapsigargin or tunicamycin. These results indicate the activation of the aforementioned expressions under regulation of the pathway, AMPK → IRS2 → Akt/PKB → PI3K (p85α). However, mammalian target of rapamycin and raptor protein, mTORC1, was found to be independent of the ER stress response. In thapsigargin treatment, melatonin increased nuclear mammalian RNA-binding protein (HuD) expression and reduced cellular HuD expression and subsequently resulted in a decrease in cellular insulin level and rise in insulin secretion in a dose-dependent manner. In tunicamycin treatment, HuD and insulin proteins showed similar expression tendencies. These results indicate that ER stress/melatonin, especially thapsigargin/melatonin, increased nuclear HuD expression and subsequently resulted in a decrease in intracellular biosynthesis; it is hypothesized that extracellular secretion of insulin may be regulated by melatonin.
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Affiliation(s)
- Yeong-Min Yoo
- Department of Biomedical Engineering, College of Health Science, Yonsei University, Wonju, Gangwon-do 220-710, Korea.
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48
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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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Kopál M, Muchová J, Ďuračková Z. Modulation of insulin resistance by PUFA in metabolic tissues. EUR J LIPID SCI TECH 2013. [DOI: 10.1002/ejlt.201200229] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Martin Kopál
- Institute of Medical ChemistryBiochemistry and Clinical BiochemistryFaculty of MedicineComenius University, BratislavaSlovakia
| | - Jana Muchová
- Institute of Medical ChemistryBiochemistry and Clinical BiochemistryFaculty of MedicineComenius University, BratislavaSlovakia
| | - Zdeňka Ďuračková
- Institute of Medical ChemistryBiochemistry and Clinical BiochemistryFaculty of MedicineComenius University, BratislavaSlovakia
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50
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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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