This proposal describes a 5 year project for training the applicant to achieve his goal to become an independent investigator in diabetes research. The training and career development plan include a compelling research project with potential clinical applications, training in laboratory techniques, and didactic scientific and career development seminars and courses. Dr. Barbara Kahn, a well-recognized leader in the field of insulin resistance and obesity, will mentor the applicant's scientific development. She has trained numerous postdoctoral fellows who now have faculty positions in academic institutions. The applicant chooses Dr. Robert Gerszten as a co-mentor. Dr. Gerszten is an Associate Professor of Medicine at Massachusetts General Hospital. Both Drs. Gerszten and Kahn are Associate members of the Broad Institute. Dr. Gerszten has been a pioneer in metabolomic analysis of cardiovascular and metabolic diseases. In addition, an advisory committee of highly-recognized experts will provide scientific and career advice. The overall goal of the project is to determine the role of Nicotinamide N-methyltransferase (NNMT) in regulating body weight and insulin sensitivity. NNMT is an enzyme that converts nicotinamide to N-methylnicotinamide. NNMT is expressed at high levels in adipocytes and liver. However its role in obesity and diabetes is not clear. The applicant's preliminary data show that NNMT expression is increased in adipose tissue and liver of obese mouse models. Knockdown of NNMT with antisense oligonucleotides (ASO) in adipose tissue and liver of mice fed a high fat diet induces expression of spermine/spermidine acetyltransferase (SSAT), a key enzyme regulating polyamine flux in adipose tissue, and causes leanness. Overexpression of NNMT in hepatocytes results in increased glucose production.
Aim #1 is to determine whether altered polyamine flux mediates the leanness caused by knockdown of NNMT.
Aim #2 is to determine whether overexpression of NNMT in adipose tissue causes obesity and whether this results from inhibition of polyamine flux. This will be achieved by establishing new adipose NNMT transgenic mice.
Aim #3 is to identify novel NNMT-regulated metabolites in adipoctyes that may contribute to obesity and insulin resistance using metabolomics analysis.
Aim #4 is to determine whether NNMT enhances hepatic gluconeogenesis by activating Sirt1, PGC-1a and FOXO1. This project will elucidate the role of a novel molecule and novel pathways in obesity and type 2 diabetes. The Department of Medicine and Division of Endocrinology at Beth Israel Deaconess Medical Center provide an ideal setting for training physician-scientists. The applicant will also have access to the resources of the Broad Institute including the metabolomics platform and bioinformatics. These outstanding resources will maximize the potential for the applicant to successfully transition to an independent investigator.
Obesity and type 2 diabetes have become public health problems. The applicant discovered that an enzyme called nicotinamide N-methyltransferase (NNMT) is increased in fat and liver of animal models with obesity and type 2 diabetes. The project will determine the critical role of NNMT in the development of obesity and type 2 diabetes. Potentially NNMT could be a new therapeutic target to prevent and treat obesity and type 2 diabetes.
|Kraus, Daniel; Yang, Qin; Kong, Dong et al. (2014) Nicotinamide N-methyltransferase knockdown protects against diet-induced obesity. Nature 508:258-62|
|Yang, Qin; Eskurza, Iratxe; Kiernan, Urban A et al. (2012) Quantitative measurement of full-length and C-terminal proteolyzed RBP4 in serum of normal and insulin-resistant humans using a novel mass spectrometry immunoassay. Endocrinology 153:1519-27|