JUVENILE-HORMONE REGULATION OF AN INSECT GENE - A SPECIFIC TRANSCRIPTION FACTOR AND A DNA RESPONSE ELEMENT

We have used locust fat body nuclear protein extracts and upstream DNA of the juvenile hormone (JH)-inducible locust gene, jhp21, to examine the regulation of specific transcription by JH. Promoter activity was assayed with G-free cassette reporter constructs. Nuclear extracts fr om adult female fat body, previously exposed to JH or an analog, activ ely transcribe from the jhp21 promoter and a control adenovirus major late (AdML) promoter, whereas extracts from JH-deprived female fat bod y, or other tissues, transcribe strongly from the AdML promoter but we akly or not at all from the jhp21 promoter. Transcription is enhanced by sequences between - 140 and - 211 nt from the jhp21 transcription s tart point (rsp), which include a CAAT box, and also by sequences betw een - 1056 and - 1200. A 15-nt partially palindromic sequence element found at - 1152, resembling known hormone response elements, was shown to stimulate transcription when restored to truncated jhp21 DNA. Two very similar sequences occur further upstream. In electrophoretic mobi lity shift assays (EMSA), the same sequence element was shown to speci fically bind a protein that was present in nuclear extracts from JH-ex posed, but not from JH-deprived, fat body. Several lines of evidence s uggest that the DNA element may be a JH response element (JHRE). The J H-induced protein that binds to it appears to be a transcription facto r that activates the initiation of JH target gene (jhp21) transcriptio n, and could be a JH receptor.