Proteomics Studies of Type 2 Diabetes Using Knockout Mouse Models

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DESCRIPTION (provided by applicant): The long term objective of this application is to gain fundamental knowledge of mechanisms and factors that promote pancreatic ¿-cell regeneration to enable improved therapeutic strategies for either preserving or regenerating of endogenous ¿-cells or for generating ¿-cells in vitro for transplantation, which are essential for the prevention and cure of diabetes. The specific goals of this five-year project are to apply global quantitative proteomic and genomic technologies to study unique insulin-resistant knockout mouse models in order to identify novel islet proteins and circulating factors that regulate ¿-cell replication and survival, and to perform functional studies on key novel protein players to gain better understanding of the mechanisms and factors that regulate islet growth. Increased ¿-cell mass/islet growth in response to insulin resistance has been observed in rodent models of diabetes and insulin resistance, human patients with obesity and/or type 2 diabetes, and other common disorders associated with insulin resistance; however, the factors contributing to ¿-cell hyperplasia in insulin-resistant states remain to be characterized. Proteomic and genomic technologies applied to unique insulin-resistant knockout models, including the liver specific insulin receptor knockout (LIRKO) and insulin receptor substrate-1 (IRS-1) knockout (IRS1KO) models, will provide unique opportunity for the identification of novel proteins and factors that are involved in this important feedback mechanism. The planned Specific Aims are: (1) to identify novel regulatory islet proteins involved in islet growth, (2) to discover new blood circulatory factors that stimulate ¿-cell regeneration, and (3) to perform functional studies for selected novel regulatory proteins and factors. The overall approach incorporates proteome-wide stable isotope 16O/18O labeling, the accurate mass and time (AMT) tag strategy, and high resolution LC separations coupled with high sensitivity Fourier transform ion cyclotron resonance (FTICR) mass spectrometry to provide broad and high throughput quantitative measurements of differential protein abundances. The tissue mRNA levels will be measured using quantitative RT-PCR technology to complement the protein abundance data. The large scale of data generated from this study is anticipated to be a valuable resource for the diabetes research community and this work will form a basis for more extensive mechanistic studies. PUBLIC HEALTH RELEVANCE: Increased pancreatic islet growth in response to insulin resistance has been commonly observed in human patients with obesity and/or type 2 diabetes; however, the factors contributing to islets hyperplasia are poorly understood. The objective of this application is to gain fundamental knowledge of mechanisms and factors that promote pancreatic islets regeneration to enable improved therapeutic strategies for the prevention and cure of diabetes by applying advanced proteomic technologies.