EXPRESSION OF THYROTROPIN-RELEASING-HORMONE RECEPTORS BY ADENOVIRUS-MEDIATED GENE-TRANSFER REVEALS THAT THYROTROPIN-RELEASING-HORMONE DESENSITIZATION IS CELL-SPECIFIC

Biological studies of seven-transmembrane region G protein-coupled rec eptors have been restricted by available techniques for gene transfer into mammalian cells. We have created a highly efficient adenovirus-ba sed expression vector for the thyrotropin-releasing hormone (TRH) rece ptor (TRH-R), AdCMVrnTRHR, to circumvent difficulties encountered when transient or stable plasmid expression systems are used. We show that infection with AdCMVmTRHR results in fully functional TRH-Rs, which c an be expressed in a broad range of mammalian cell types, including th ose resistant to conventional transient transfection. TRH-Rs can be ex pressed at high levels, up to 2 x 10(6) receptors/cell. Expression in several cell lines in culture reveals that rapid TRH-R desensitization by TRH and phorbol 12-myristate 13-acetate is cell type specific. The versatility of adenovirus-mediated gene transfer and expression of TR H-Rs not only facilitates in vitro studies of TRH-R biology but also p rovides a valuable in vivo expression vector capable of extending TRH- R studies to animal model systems.