Insect Mimetics Research Unit, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan.
Insect Biochem Mol Biol. 2012 Jul;42(7):474-81. doi: 10.1016/j.ibmb.2012.03.004. Epub 2012 Mar 29.
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.
Ets 家族蛋白 BmEts 被认为参与了家蚕胚胎发生中滞育的决定。在这项研究中，我们发现 BmEts 的表达在 5 龄幼虫的脂肪体和其他组织中因大肠杆菌注射而增加。使用家蚕细胞系的共转染实验表明，BmEts 的过表达显著提高了 lebocin 启动子的活性，但不提高 cecropin B1、cecropin D、attacin 和 moricin 启动子的活性。BmEts 对 lebocin 启动子的激活依赖于至少两个 κB 元件和位于 5'-上游区域的最近端 GGAA/T 基序。BmEts 还进一步协同增强了大肠杆菌或 BmRelish1-d2（活性形式）刺激的 lebocin 启动子激活。两个 κB 元件也被发现参与 BmRelish1-d2 启动子的激活以及 BmEts 和 BmRelish1-d2 在蚕细胞中的协同启动子激活。还观察到重组 BmEts 与近端 κB 元件和最近端 GGAA/T 基序的特异性结合以及 BmEts 和 BmRelish1 之间的相互作用。据我们所知，这是第一个报道 Ets 家族蛋白在家蚕中直接调节免疫相关基因的报告。
