The Ets family protein BmEts is assumed to be implicated in determination of diapause in the embryogenesis of . Bombyx mori. In this study, we found that expression of . BmEts was increased in the fat body and other tissues of the 5th instar larvae in response to . Escherichia coli injection. Cotransfection experiments using a silkworm cell line revealed that overexpression of BmEts significantly elevated the activity of . lebocin promoter but not of . cecropin B1, . cecropin D, . attacin, and . moricin promoters. Activation of the . lebocin promoter by BmEts was dependent on at least two κB elements and the most proximal GGAA/T motif located on the 5'-upstream region. BmEts further synergistically enhanced . E. coli or BmRelish1-d2 (active form)-stimulated . lebocin promoter activation. Two κB elements were also found to be involved in promoter activation by BmRelish1-d2 and in synergistic promoter activation by BmEts and BmRelish1-d2 in the silkworm cells. Specific binding of recombinant BmEts to the proximal κB element and the most proximal GGAA/T motif and interaction between BmEts and BmRelish1 were also observed. To our knowledge, this is the first report of an Ets family protein directly regulating immune-related genes in invertebrates.
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