This is a competitive renewal of NIH grant DK31036. This grant is now completing 28 years and a 10-year cycle since receiving a merit extension by NIDDK. Since its inception, the grant has been focused on the insulin receptor, and to a lesser extent IGF-1 receptor, and their signaling capabilities and their alterations in physiologic and pathologic states. Since the last renewal, we have made very substantial progress in understanding the signaling and biological roles of these receptors through both in vitro and in vivo studies. The largest body of studies derived from the use of homologous recombination gene targeting to study the role of the insulin receptor in insulin action in vivo. This has included the use of single gene knockouts of the insulin and IGF-1 receptors;combinatorial homozygous and heterozygous knockouts as polygenic models of Type 2 diabetes;and tissue-specific knockouts using the Cre-lox approach to determine the role of the insulin and IGF-1 receptors in individual tissues in the physiology of glucose and lipid homeostasis and the pathophysiology of diabetes and metabolic syndrome. In addition, we have performed a series of in vitro studies focusing on differential signaling by the insulin and IGF-1 receptors in the actions of insulin and IGF-1. As a result, since the last competitive renewal, this grant has provided support for a total of 90 published papers (including 48 original articles, 26 collaborative articles and 16 reviews). This work has led to development of new hypotheses about the nature of the insulin/IGF-1 signaling network, the contribution of insulin resistance in different organs to diabetes and the metabolic syndrome, as well as new evidence on how tissues communicate with one another in insulin resistant states, a role for insulin signaling in fat in longevity and a role for insulin signaling in the brain in neurodegeneration. In unpublished studies, we have also developed data on the role of the insulin receptor in brain in the control of CNS cholesterol metabolism and a novel role of signaling from the unoccupied insulin and IGF-1 receptors in control of apoptosis which appears to be kinase independent.
The specific aims for the next grant period are: 1) Explore the role of insulin and IGF-1 signaling in increased longevity, stress resistance and mitochondrial metabolism in mice with selective insulin resistance in fat or brain. 2) Study the role of insulin signaling in the brain on regulation of brain cholesterol metabolism and the relationship of CNS insulin resistance and altered cholesterol metabolism to neurodegeneration. 3) Determine the nature of tyrosine kinase independent signaling by the unoccupied insulin and IGF-1 receptors involved in control of apoptosis. 4) Define the differential nature of insulin and IGF-1 receptor signaling in vivo by creation of a new generation of mouse models in which the insulin receptor is replaced by knocking of the IGF1 receptor or a chimeric insulin/IGF-1 receptor to produce mice and cell lines that express each receptor or chimeric receptor in the tissue and temporal pattern of the other receptor.
This grant, now completing 28 years and a merit extension, is focused on the insulin receptor, and to a lesser extent the highly related IGF-1 receptor, their signaling capabilities and their alterations in physiologic and pathologic states such as diabetes and metabolic syndrome. Since the last renewal, we have made very substantial progress in understanding the roles of these receptors through creation and characterization of a large number of mice genetically engineered to have insulin or IGF-1 resistance in only one tissue at a time. This work has led an integrated view of the role of insulin resistance in diabetes and metabolic syndrome, as well as a number of new insights into previously unrecognized aspects of insulin signaling, which form the basis of the proposed experiments going forward.
|Emanuelli, Brice; Vienberg, Sara G; Smyth, Graham et al. (2014) Interplay between FGF21 and insulin action in the liver regulates metabolism. J Clin Invest 124:515-27|
|Boucher, Jeremie; Charalambous, Marika; Zarse, Kim et al. (2014) Insulin and insulin-like growth factor 1 receptors are required for normal expression of imprinted genes. Proc Natl Acad Sci U S A 111:14512-7|
|Kleinridders, André; Ferris, Heather A; Cai, Weikang et al. (2014) Insulin action in brain regulates systemic metabolism and brain function. Diabetes 63:2232-43|
|Boucher, Jérémie; Kleinridders, André; Kahn, C Ronald (2014) Insulin receptor signaling in normal and insulin-resistant states. Cold Spring Harb Perspect Biol 6:|
|Bezy, Olivier; Tran, Thien T; Pihlajamaki, Jussi et al. (2011) PKCýý regulates hepatic insulin sensitivity and hepatosteatosis in mice and humans. J Clin Invest 121:2504-17|
|Sanchez-Alavez, Manuel; Osborn, Olivia; Tabarean, Iustin V et al. (2011) Insulin-like growth factor 1-mediated hyperthermia involves anterior hypothalamic insulin receptors. J Biol Chem 286:14983-90|
|Boucher, Jeremie; Macotela, Yazmin; Bezy, Olivier et al. (2010) A kinase-independent role for unoccupied insulin and IGF-1 receptors in the control of apoptosis. Sci Signal 3:ra87|
|Suzuki, Ryo; Lee, Kevin; Jing, Enxuan et al. (2010) Diabetes and insulin in regulation of brain cholesterol metabolism. Cell Metab 12:567-79|
|Boucher, Jeremie; Tseng, Yu-Hua; Kahn, C Ronald (2010) Insulin and insulin-like growth factor-1 receptors act as ligand-specific amplitude modulators of a common pathway regulating gene transcription. J Biol Chem 285:17235-45|
|Mauer, Jan; Chaurasia, Bhagirath; Plum, Leona et al. (2010) Myeloid cell-restricted insulin receptor deficiency protects against obesity-induced inflammation and systemic insulin resistance. PLoS Genet 6:e1000938|
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