The syndrome of drug addiction severely damages the lives of affected patients and their families, and exacts an enormous economic toll on the United States. Although scientific data has demonstrated a hereditary predisposition to drug abuse it has been difficult to correlate these findings with specific genomic loci, suggesting epigenetic mechanisms may underlie the addicted phenotype. Recent evidence has emerged that chronic cocaine exposure regulates expression of several histone-modifying enzymes and transcription factors, as well as induces global changes in chromatin structure. For example, the chromatin structure and expression of the fosB gene is regulated by chronic cocaine in specific brain reward regions in both rodent models and human patients. This proposal outlines the highly innovative use of engineered zinc-finger proteins (ZFPs) as novel molecular tools to study the epigenetic mechanisms underlying drug addiction. ZFPs are DNA-binding proteins that can direct transcriptional regulation to a single gene locus in the context of the whole genome. The first specific aim is to characterize the regulation of fosB gene expression by FosB-ZFPs in vitro and in vivo, using viral-mediated expression in the mouse ventral striatum followed by protein and mRNA expression analysis. The second specific aim is to determine the use of FosB-ZFPs as novel modulators of cocaine-mediated behavior by analyzing the behavior of mice expressing FosB-ZFPs in paradigms measuring cocaine sensitivity and preference. The third specific aim is to characterize the epigenetic modifications underlying fosB transcriptional regulation by FosB-ZFPs expressed in mouse ventral striatum, using chromatin-immunoprecipitation to identify histone modifications and transcription factor binding at the fosB gene. Through the innovative and comprehensive research strategy detailed in this proposal, the applicant, Dr. Elizabeth Heller, will gain extensive training in new behavioral and molecular biology techniques, which are vital to a career in drug abuse research at a top academic institution. The proposed site of research, the Mount Sinai School of Medicine, is a state-of-the-art institution, providing the technologically advanced resources necessary to carry out the proposed research. The sponsor, Dr. Eric Nestler, is a world-renowned drug abuse researcher, who will provide the ideal collaborative environment to train Dr. Heller in preparation for a caree in drug abuse research. The research proposed here will shed new light on the mechanisms of transcriptional regulation by drugs of abuse, as well as demonstrate the use of ZFPs as novel tools in the study of the neurobiology of drug addiction.