EXPRESSION CLONING OF A HUMAN CORTICOTROPIN-RELEASING-FACTOR RECEPTOR

Corticotropin-releasing factor (CRF) is the principal neuroregulator of the hypothalamic-pituitary-adrenocortical axis and plays an important role in coordinating the endocrine, autonomic, and behavioral responses to stress and immune challenge. We report here the cloning of a cDNA coding for a CRF receptor from a human corticotropic tumor library. The cloned cDNA encodes a 415-amino add protein comprising seven putative membrane-spanning domains and is structurally related to the calcitonin/vasoactive in peptide/growth hormone-releasing hormone subfamily of G protein-coupled receptors. The receptor expressed in COS cells binds rat/human CRF with high affinity (K(d) = 3.3 +/- 0.45 nM and specificity and is functionally coupled to adenylate cyclase. The CRF antagonist alpha-helCRF-(9-41) inhibits the CRF-stimulated increase in intracellular cAMP. Northern blot analysis reveals that the CRF receptor is expressed in the rat pituitary and brain as well as in the mouse AtT20 corticotropic cells. We also describe an alternatively spliced form of the receptor which includes an insert of 29 amino acids in the first intracellular loop.