Principal Investigators: |
|
| Dr. rer. nat. Antje Garten | Prof. Dr. med. Wieland Kiess |
| Child and Adolescent Medicine Clinic, Pediatric Research Center | Child and Adolescent Medicine Clinic |
| Universität Leipzig | Universität Leipzig |
| Liebigstraße 21 | Liebigstraße 20 a |
| 04103 Leipzig | 04103 Leipzig |
| Phone: +49 341 97 26504 | Phone: +49 341 97 26000 |
| Fax: +49 341 97 26069 | Fax: +49 341 97 26009 |
| antje.garten@medizin.uni-leipzig.de | wieland.kiess@medizin.uni-leipzig.de |
Summary of the Subproject:
Nampt is a key enzyme of the human NAD biosynthesis originating from nicotinamide. Intracellular Nampt affects the activity of NAD dependent enzymes (e.g. sirtuins), which influence cellular stress responses as well as cell metabolism. Nampt secreted from adipocytes produces nicotinamide mononucleotide (NMN) which causes an increase of insulin secretion in a heterozygous Nampt knock-out mouse model. Based on these results we want to 1) characterize the function of intracellular Nampt in the metabolism of human hepatocytes and 2) investigate the relevance of secreted Nampt in human glucose metabolism. The experiments will be carried out in HepG2 cells and – for verification – in human hepatocytes. 1) By means of an inducible Nampt overexpression model we will analyze the influence of Nampt activity on metabolic end points of the glucose and lipid metabolism. Additionally, we are going to investigate to what extent Nampt expression affects the resistance to cell stress. 2) The enzymatic activity of extracellular Nampt will be quantified by an enzyme assay and NMN and NAD will be measured by HPLC. Subsequently, the biological effects of NMN on glucose metabolism will analyzed in several cell models (measurement of relevant cell responses, e.g. glucose uptake, glucose synthesis).
Publications:
- Olesen UH, Petersen JG, Garten A, Kiess W, Yoshino J, Imai SI, Christensen MK, Fristrup P, Thougaard AV, Bjorkling F, Jensen PB, Nielsen SJ, Sehested M. Target enzyme mutations are the molecular basis for resistance towards pharmacological inhibition of nicotinamide phosphoribosyltransferase. BMC Cancer. 2010;10:677.
- Vogel R, Garten A, Klammt J, Barnikol-Oettler A, Kiess W. Activation of Erk1/2 phosphorylation but not of Akt/Pkb through an inducible CSF1R/IRR-receptor construct in INS-1E beta-cells. Arch Physiol Biochem. 2010;116:128-36.
- Garten A, Petzold S, Barnikol-Oettler A, Körner A, Thasler WE, Kratzsch J, Kiess W, Gebhardt R. Nicotinamide phosphoribosyltransferase (NAMPT/PBEF/visfatin) is constitutively released from human hepatocytes. Biochem Biophys Res Commun. 2010;391:376-81.
- Garten A, Petzold S, Körner A, Imai S, Kiess W. Nampt: linking NAD biology, metabolism and cancer. Trends Endocrinol Metab. 2009;20:130-8.
- Revollo JR, Körner A, Mills KF, Satoh A, Wang T, Garten A, Dasgupta B, Sasaki Y, Wolberger C, Townsend RR, Milbrandt J, Kiess W, Imai S. Nampt/PBEF/Visfatin regulates insulin secretion in beta cells as a systemic NAD biosynthetic enzyme. Cell Metab. 2007;6:363-75.