Identification of thyroid hormone response element of atrial natriuretic factor

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Atrial natriuretic factor(ANF) is a hormone that dilates vasculature and induces natriuresis, and is synthesized and secreted from atrial myocytes. We have demonstrated for the first time that thyroid hormone(T_3)stimulates synthesis and release of ANF from atrial myocytes, and that its stimulatory effect is mediated through gene transcription. To characterize the T_3 response element(TRE)of ANF promoter, we deletion-mutated 2.4Kb of the 5' flanking region toward the downstream and fucked 5' end of chrolamphenicol acetyltransferase(CAT)gene. These deletion-mutated CAT constructs were transfected into the atrial myocytes. We identified the TRE in the region located in -108 to -68bp. The gel shift assay demonstrates that this region binds to the nuclear factor induced by the addition of T_3 and no retarded band was observed in the nuclear extract in the absence of T_3. No consensus TRE motif previously recognized was detected in -108 to -68. Thus, we characterized the TRE specific for ANF gene in -108 to -68 from the transcription site, the sequence of which conferred the T_3 responsiveness to the ANF gene.