Transgenic Ectopic Overexpression of Broad Complex (BrC-Z2) in the Silk Gland Inhibits the Expression of Silk Fibroin Genes ofBombyx mori
Transgenic Ectopic Overexpression of Broad Complex (BrC-Z2) in the Silk Gland Inhibits the Expression of Silk Fibroin Genes ofBombyx mori
复制标题
丝腺中转基因异位表达Broad复合物(BrC-Z2)抑制家蚕丝素蛋白基因的表达
DOI：
10.3390/insects11060374
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发表时间：
2020-06-01
期刊：
影响因子：
3
通讯作者：
Liu, Chun
中科院分区：
文献类型：
--
作者：
Cong, Jiangshan;Tao, Cuicui;Liu, Chun
家蚕丝蛋白基因在不同发育阶段受激素周期性变化的影响而严格开启和关闭。广泛复合体（Broad Complex，BrC）是介导20-羟基蜕皮激素作用的转录因子，在变态过程中发挥重要作用。在此，我们观察到BmBrC的两种异构体（BmBrC-Z2和BmBrC-Z4）在后部丝腺（PSG）中表现出与丝素基因（FibH、FibL和P25）相反的表达模式，表明BmBrC可能负调控丝素基因。构建转基因系以在PSG中异位过表达BmBrC-Z2。转基因株系中的丝蛋白基因减少到野生型的近一半。产丝量显著下降。此外，对保幼激素（JH）信号应答的调节因子BmKr-h1和BmDimm的表达水平也受到显著抑制。在BmBrC-Z2过表达系中外源JH可抑制BmBrC-Z2的表达，激活丝蛋白基因的表达，使产丝量恢复到野生型水平。这些结果表明，BmBrC可能通过抑制JH信号通路来抑制丝素蛋白基因的表达，这将有助于揭示丝素蛋白基因的综合调控机制。
Bombyx mori silk protein genes are strictly turned on and off in different developmental stages under the hormone periodically change. The broad complex (BrC) is a transcription factor mediating 20-hydroxyecdysone action, which plays important roles during metamorphosis. Here, we observed that two isoforms of BmBrC (BmBrC-Z2 and BmBrC-Z4) exhibited contrasting expression patterns with fibroin genes (FibH, FibL and P25) in the posterior silk gland (PSG), suggesting that BmBrC may negatively regulate fibroin genes. Transgenic lines were constructed to ectopically overexpress BmBrC-Z2 in the PSG. The silk protein genes in the transgenic line were decreased to almost half of that in the wild type. The silk yield was decreased significantly. In addition, the expression levels of regulatory factors (BmKr-h1 and BmDimm) response to juvenile hormone (JH) signal were inhibited significantly. Then exogenous JH in the BmBrC-Z2 overexpressed lines can inhibit the expression of BmBrC-Z2 and activate the expression of silk protein genes and restore the silk yield to the level of the wild type. These results indicated that BmBrC may inhibit fibroin genes by repressing the JH signal pathway, which would assist in deciphering the comprehensive regulation mechanism of silk protein genes.