Induction of an intronic enhancer of the human ciliary neurotrophic factor receptor (CNTFRalpha) gene by the TR3 orphan receptor.

A hormone response element, CNTFRalpha-NBRE (5'-AAAGGTCA-3') has been identified in the fifth intron of the alpha component of ciliary neurotrophic factor receptor gene (CNTFR-15) for the human TR3 orphan receptor (TR3). A specific binding between in vitro expressed TR3 and CNTFRalpha-NBRE was demonstrated by using electrophoretic mobility shift assay. A reporter gene assay using chloramphenicol acetyl-transferase (CAT) showed that CNTFR-15 has an enhancer activity that could be induced by TR3 in a dose-dependent manner. This induction was significantly reduced in the absence of CNTFRalpha-NBRE. Together, these results indicate CNTFRalpha-NBRE is sufficient to mediate TR3 action in inducing the enhancer activity of CNTFR-15. Our finding may, therefore, suggest CNTFRalpha is a target gene regulated by TR3 and expand the role of TR3 in the nervous system.