Obesity, which is associated with hypertrophy and hyperplasia of adipocytes, is associated with many chronic diseases including insulin resistance and diabetes, heart disease, hypertension, and cancer. Chronic inflammation and activation of the innate immune system may lie at the heart of many of these diseases; overnutrition is known to cause inflammation in adipocytes and adipose tissue. However, the molecular mechanisms that initiate these inflammatory events in adipocytes are largely unknown, particularly at the transcriptional level. Previous work has shown that the transcription factor Early B-Cell Factor-1 (Ebf1) regulates numerous signaling pathways and promotes inflammation in adipocytes; however, the precise molecular mechanisms through which Ebf1 regulates expression of inflammatory loci remains unknown. We have recently discovered that Ebf1 can physically interact with multiple subunits of the well-known inflammatory transcription factor NF-?B, and many of the same inflammatory loci that are decreased in expression in Ebf1- deficient 3T3-L1 adipocytes are also known NF-?B target genes, suggesting that Ebf1 and NF-?B may work together to induce expression of inflammatory chemokines and other proteins in adipocytes. To determine the role of Ebf1 in vivo, and to investigate Ebf1 regulation of inflammatory pathways independent of its role in differentiation, we have developed Fat-Specific Ebf1 Knockout (FEBKO) mice. This model provides us a unique opportunity to examine the functional consequences of Ebf1 deficiency in the context of adipose tissue.
The specific aims are to 1) fully characterize the Ebf1-NF-?B interaction, including mapping the interaction domains, determining if the interactions are direct, and whether the two proteins can synergistically activate NF-?B reporter models; 2) determine if NF-?B DNA binding and/or transactivation are impaired in Ebf1-deficient adipocytes; and 3) perform metabolic characterization of the FEBKO animals. These studies will provide insight into the molecular mechanisms governing expression of inflammatory chemokines and other proteins in adipocytes, and may uncover novel ?druggable? targets in obesity and diabetes. Development of compounds that specifically disrupt the Ebf1-NF-?B protein-protein interactions could potentially abate inflammation in adipocytes, with minimal side effects, since Ebf1 expression is relatively adipose-specific. Finally, the proposed research will provide abundant opportunities for Midwestern University (MWU) students to become involved in obesity/diabetes-related research, from in vitro bench work to in vivo physiological work to analysis and interpretation of data. This includes students from the Master?s in Biomedical Sciences (MBS) program, the Arizona College of Osteopathic Medicine (AZCOM) program, and possibly others (e.g., the new Veterinary Medicine program). This project will fill a much-needed niche for MWU students who are interested in participating in obesity/diabetes research, hopefully incite them to incorporate research into their careers, and will serve to strengthen the research environment at our institution at multiple levels.
Obesity is associated with multiple metabolic diseases including insulin resistance, diabetes, hypertension, heart disease, atherosclerosis, some forms of arthritis, and even cancer. Nearly two decades? worth of evidence has indicated that chronic inflammation in adipose tissue (fat cells)?which often accompanies prolonged overnutrition?may represent a major underlying cause of many of these diseases. We have identified a key gene that controls adipocyte inflammation; thoroughly understanding how this gene works may pave the way for development of novel therapeutics aimed at treating metabolic disease.
