Notch and Regulators of Notch Signaling Impact Both Glucose and Lipid Metabolism

点击翻译按钮获取中文摘要

DESCRIPTION (provided by applicant): This proposal describes a five year plan for Utpal Pajvani to transition to an independently-funded investigator, a clinician/scientist with a focus on translational research. Dr. Pajvani received MD and PhD degrees from the Albert Einstein College of Medicine in 2005, the latter degree earned in defining the biochemistry of the adipocyte-secreted hormone, adiponectin, and subsequently performed medical training in Internal Medicine and Endocrinology at Columbia University. Dr. Pajvani's clinical training cemented his intent to translate research to benefit patients, whether it be through the discovery of a novel pathway in the development of insulin resistance, or application of a known therapeutic agent from cancer biology to the metabolic syndrome. The goals of the proposed training are to provide training and mentoring to prepare Dr. Pajvani for an independent research career, and additionally, to answer fundamental, lingering questions on the pathogenesis of insulin resistance and its treatment. Type 2 diabetes is associated with obesity and generalized insulin resistance; currently available insulin sensitizers are only partially effective at improving glucose disposal in skeletal muscle and suppressing glucose production in liver. A more detailed knowledge of pathways that influence insulin resistance is necessary to identify new targets for the development of drugs that will assist in the management of diabetic patients. In this application, Dr. Pajvani describes preliminary data that reveal the novel role of the Notch family of transmembrane receptors, traditionally thought only to mediate normal development and thereafter remain quiescent unless inappropriately activated in cancer, in regulation of hepatic metabolism through its interaction with FoxO1, a transcription factor known to modulate insulin sensitivity. Through detailed metabolic analyses in compound haploinsufficient (FoxO1:Notch1) mice, Dr. Pajvani and one of his mentors, Domenico Accili, determined that genetic inhibition of hepatic Notch action demonstrated beneficial effects in both glucose and lipid homeostasis. These effects were recapitulated by pharmacologic inhibitors of Notch action, which were able to markedly improve glucose tolerance in diet- induced and genetic models of obesity. Dr. Pajvani proposes in this application (i) to characterize the Notch pathway in states of insulin resistance, (ii) to determine the mechanism of the differential effects of Notch and its pharmacological inhibitors on glucose and lipid metabolism, and (iii) to study the effects of inhibition of Notch signaling with pharmacologic tools (small molecule inhibitors or monoclonal antibodies) or other genetic mouse models of Notch hypofunction. Additionally, Dr. Pajvani proposes an observational clinical study to determine if hepatic expression of Notch pathway components correlates with measures of insulin resistance, hyperlipidemia and/or hepatic steatosis in obese and diabetic patients. The goal of these studies is to demonstrate whether inhibition of Notch signaling is a viable therapeutic target in the correction of hyperglycemia and dyslipidemia characteristic of obesity-induced insulin resistance and the metabolic syndrome. Dr. Pajvani's overall career objective is to be able to translate the seminal discoveries made at the bench into therapeutic application in patients he sees at the Naomi Berrie Diabetes Center and inpatient Endocrinology and Metabolism service at Columbia University Medical Center. His patient care responsibilities, beyond providing personal satisfaction, allow Dr. Pajvani to approach scientific questions with pragmatism and with a sense of urgency. These same responsibilities encourage continued research training, as outlined in this application. The training he still needs to understand and fruitfully apply epidemiology and statistical methods in the design and analysis of clinical research studies, can best be addressed through continued study at Columbia University. Furthermore, the scientific knowledge required to integrate hepatic insulin signaling on glucose and lipid metabolism, as well as the multifaceted aspects of FoxO1 and Notch biology, can best be addressed through his choice of mentors (Drs. Domenico Accili and Jan Kitajewski) and advisors (Drs. Henry Ginsberg, Ira Goldberg and Robin Goland), all respected investigators who value mentoring young and aspiring faculty members. Finally, the Columbia University Medical Center environment brings together access to a diverse patient population and all the facilities and faculty developmental tools that Dr. Pajvani will need in order to become an independent translational medical researcher and a productive member of the academic medical community.