A locust DNA-binding protein involved in gene regulation by juvenile hormone

Although juvenile hormone (JH) has essential roles in insect development and reproduction, the molecular mechanisms of gene regulation by JH remain an enigma. In Locusta migratoria, the partially palindromic 15-nt sequence, GAGGTTCGAG(A)/(T)CCT(T)/(C), found upstream of a JH-induced gene, jhp21, was designated as a putative juvenile hormone response element (JHRE). When JH-deprived adult female locusts were treated with the active JH analog, methoprene, a fat body nuclear factor that bound specifically to JHRE appeared after 24 h. Binding exhibited a preference for an inverted repeat with GAGGTTC in the left half-site, a single nucleotide spacer, and a right half-site in which some variation is acceptable. Binding to JHRE was abolished by phosphorylation catalyzed by a C-type protein kinase present in the nuclear extracts. The DNA-binding protein is thus believed to be a transcription factor, which is brought to an active state through the action of JH and then participates in the regulation of certain JH-dependent genes.