Excessive hepatic glucose production is a hallmark of Type II diabetes. An important function of insulin in the liver is the suppression of hepatic glucose production. This is partly mediated via reducing the transcription of two key gluconeogenic enzymes, phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6- phosphatase (G-6-Pase). Adipocyte-specific secreted molecules, termed adipokines, have highlighted the role of adipose tissue as an active endocrine organ that regulates metabolism and maintains energy homeostasis. Adiponectin has gained significant attention recently as a mediator of hepatic insulin sensitivity. In contrast, resistin has been shown to have a potent negative impact on hepatic insulin sensitivity. The ability of both of these proteins to form higher order complex structures is an essential aspect of their bioactivity that results in the modulation of the insulin-induced transcriptional changes of PEPCK and G-6-Pase, resulting in changes in hepatic glucose output. Under the auspices of this R24 application, we propose to integrate independent efforts of the four participating laboratories towards the characterization of the underlying mechanisms by which adipokines influence hepatic glucose fluxes in vivo. A detailed structure/function analysis will be performed on adiponectin and resistin to identify the critical determinants that enable these complexes to exert their effects on the downstream targets. The bioactivity of both key mediators of this process, adiponectin and resistin, is critically dependent on the formation and disruption of essential disulfide bonds, yet how the reduction of these disulfide bonds affects conformation is not clear. Metabolic clamp studies will be performed in models of impaired or increased hepatic insulin sensitivity, obtained through perfusion of adiponectin or resistin, in combination with gain- and loss-of-function mutations of potentially critical downstream targets, AMPK and Foxo1. These experiments will be complemented with similar studies in tissue culture cells. The short-term goal of this proposal is to gain a better molecular understanding of the adipo-hepatic signaling axis and how it affects glucose fluxes within the liver. The longer-term goal consists of forging closer collaborative ties between investigators in two leading Diabetes Centers in the New York City area with a vision towards much closer inter-institutional efforts in the area of obesity and diabetes research in the future.
| Rutkowski, Joseph M; Davis, Kathryn E; Scherer, Philipp E (2009) Mechanisms of obesity and related pathologies: the macro- and microcirculation of adipose tissue. FEBS J 276:5738-46 |
| Khan, Tayeba; Hamilton, Mark P; Mundy, Dorothy I et al. (2009) Impact of simvastatin on adipose tissue: pleiotropic effects in vivo. Endocrinology 150:5262-72 |
| Nagajyothi, Fnu; Desruisseaux, Mahalia S; Thiruvur, Niranjan et al. (2008) Trypanosoma cruzi infection of cultured adipocytes results in an inflammatory phenotype. Obesity (Silver Spring) 16:1992-7 |
| Nagajyothi, Fnu; Desruisseaux, Mahalia S; Thiruvur, Niranjan et al. (2008) Trypanosoma cruzi Infection of Cultured Adipocytes Results in an Inflammatory Phenotype. Obesity (Silver Spring) : |
| Halberg, Nils; Wernstedt-Asterholm, Ingrid; Scherer, Philipp E (2008) The adipocyte as an endocrine cell. Endocrinol Metab Clin North Am 37:753-68, x-xi |
| Schraw, Todd; Wang, Zhao V; Halberg, Nils et al. (2008) Plasma adiponectin complexes have distinct biochemical characteristics. Endocrinology 149:2270-82 |
| Wang, Zhao V; Scherer, Philipp E (2008) Adiponectin, cardiovascular function, and hypertension. Hypertension 51:8-14 |
| Asterholm, Ingrid Wernstedt; Halberg, Nils; Scherer, Philipp E (2007) Mouse Models of Lipodystrophy Key reagents for the understanding of the metabolic syndrome. Drug Discov Today Dis Models 4:17-24 |
| Lin, Hua V; Kim, Ja-Young; Pocai, Alessandro et al. (2007) Adiponectin resistance exacerbates insulin resistance in insulin receptor transgenic/knockout mice. Diabetes 56:1969-76 |
| Kim, Ja-Young; van de Wall, Esther; Laplante, Mathieu et al. (2007) Obesity-associated improvements in metabolic profile through expansion of adipose tissue. J Clin Invest 117:2621-37 |
Showing the most recent 10 out of 16 publications
