PROJECT DESCRIPTION This project will chart with high-resolution the genetic pathways that give rise to defined clinical phenotypes related to cocaine addiction. We will utilize the power of the hybrid mouse diversity panel (HMDP), combined with high quality behavioral phenotyping and massive-scale RNA sequencing, to trace the interconnections from DNA to RNA to clinical trait and provide layered information on the mechanisms of cocaine abuse. The HMDP consists of 100 inbred and recombinant inbred strains and has a wide array of meiotic breakpoints. The panel has been densely genotyped with more than 200,000 single nucleotide polymorphisms (SNPs), allowing very fine mapping of quantitative trait loci (QTLs). Further, the HMDP is genetically stable and renewable and can be assayed for multiple phenotypes, yielding cumulative biological information. We will expand our previous HMDP-based studies of cocaine abuse-related traits by adding massive-scale RNA sequencing (RNA-Seq), in order to detail the genetic control of the pathways to addiction. Our approach offers the distinct advantage of mapping loci for known pathways as well as those involving variant and exotic RNA species. The following aims are proposed: (1) We will quantitate intravenous self-administration of cocaine in HMDP mice. This phenotype is regarded as being one of the most faithful models of cocaine abuse in animals and will allow evaluation of QTLs that regulate addiction-related phenotypes. (2) We will perform RNA-Seq on two key areas of the brain that play a role in the control of drug abuse, the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) shell region. (3) We will analyze the combined datasets with powerful statistical tools to understand the genetic regulation of drug abuse-related phenotypes. These studies will map genetic networks and inter-tissue regulatory pathways for cocaine addiction and suggest new, highly specific therapeutic strategies.