Defining the Genomic Responses to G Protein Signals by Engineering Receptors and G Proteins in Transgenic Mice

Bruce Conklin
University of California at San Francisco

We are interested in how G protein coupled receptors (GPCRs) control electrically active tissues. In tissues such as the heart and the brain, GPCRs orchestrate the intracellular biochemical signals with the actions of ion channels at the cell surface. Prolonged signaling results in changes in gene expression, new levels of responsiveness and occasionally pathological states. To best understand this process we have devised several new methods to control G protein signals in vivo and use new techniques to monitor signaling events on a genomic level. Our four primary avenues of research are: A. New Receptors: using engineered receptors and G proteins. To take control of signaling at the receptor level, we have engineered versions of the kappa opioid receptor (KOR) to be unresponsive to the endogenous levels of natural hormones but still be activated by administration of synthetic small molecule drugs. These modified receptors are called a RASSLs (Receptor Activated Solely by a Synthetic Ligand). B. Constitutively Active G Proteins: We have expressed constitutively active versions of G proteins under the temporal-spatial control of the tetracycline transactivator system in mice. Several different G protein-specific phenotypes have resulted, providing an alternative strategy for identifying the principal responses to G protein signals in vivo. C. Signal Monitoring in Vivo: We are currently using DNA arrays that simultaneously monitor the gene expression levels for over 11,000 mouse genes. Preliminary studies suggests that each G protein pathway has a unique pattern of gene expression. D. GenMAPP: We are developing a software package called GenMAPP (Gene MicroArray Pathway Profiler) that allows for the rapid analysis of large amounts of gene expression data by mapping changes in specific genes onto known biochemical pathways and signaling pathways. The GenMAPP software consists of two components, an analyzer and a drafter that allows users to use predefined pathays or create their own pathways, then map expression data directly onto these pathways. For more information, please see our laboratory's website: http://gladstone.ucsf.edu/labs/conklin/ or: www.GenMAPP.org


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