Gene expression profiling reveals corticotropin-releasing hormone (CRH) dependent signaling pathways

The biological actions of CRH-like neuropeptides are mediated by G protein-coupled heptahelical receptors, CRH receptor 1 (CRHR1) and CRHR2. Ligand binding transforms the conformation of respective receptor into an active state thereby increasing its affinity for G proteins. Binding of a G_s protein will lead to stimulation of adenylate cyclase and acitvation of protein kinase A (PKA) and other cAMP dependent pathways. The reported coupling of additional G proteins to CRHR1 suggests that also other second messengers (e.g. inositol phosphates or Ca²⁺) might be involved in CRH receptor signaling.In order to elucidate CRH-dependent signaling pathways we applied cDNA microarray technology. Our custom-made MPIP 24k mouse cDNA array contains approximately 24.000 GenBank clones which in turn represent 18.000 unique UniGene clusters. Optimized standard procedures for template generation, labeling, hybridization, data acquisition and analysis ensure reproducible results and allow meaningful comparisons of expression levels, a prerequisite for the subsequent selection of candidate genes for further analysis. Array experiments were performed using corticotroph AtT–20 cells and primary hippocampal cultures. The biostatistic evaluation of acquired data identified numerous regulated genes of which several candidates were confirmed. The function of individual candidate genes is currently under investigation and will reveal novel insights into CRH dependent signal transduction pathways.