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 receptors have been restricted by available techniques for gene transfer into mammalian cells. We have created a highly efficient adenovirus-based expression vector for the thyrotropin-releasing hormone (TRH) receptor (TRH-R), AdCMVmTRHR, 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 can be expressed in a broad range of mammalian cell types, including those resistant to conventional transient transfection. TRH-Rs can be expressed 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 TRH-Rs not only facilitates in vitro studies of TRH-R biology but also provides a valuable in vivo expression vector capable of extending TRH-R studies to animal model systems.