Lu Kai, Zhou Jinming, Chen Xia, Li Wenru, Li Yue, Cheng Yibei, Yan Jing, You Keke, Yuan Zhineng, Zhou Qiang
State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.
College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China.
Front Physiol. 2018 Oct 30;9:1535. doi: 10.3389/fphys.2018.01535. eCollection 2018.
Provisioning of sufficient lipids and vitellogenin to the oocytes is an indispensable process for fecundity of oviparous insects. Acute mobilization of lipid reserves in insects is controlled by the Brummer (Bmm), an orthologous of human adipose triglyceride lipase (ATGL). To investigate the functional roles of brummer-mediated lipolysis in the fecundity of the brown planthopper, , RNA interference (RNAi) analyses were performed with double-stranded RNA (dsRNA) against in adult females. Knockdown of expression resulted in obesity and blocked lipid mobilization in the fat body. In addition, silencing led to retarded ovarian development with immature eggs and less ovarioles, decreased number of laid eggs, prolonged preoviposition period and egg duration. Furthermore, severe reductions of vitellogenin and its receptor abundance were observed upon knockdown. The transcript levels of (juvenile hormone esterase) which degrades JH were up-regulated, whereas the expression levels of JH receptors (Methoprene-tolerant) and (Taiman) and their downstream transcription factors (Krüppel-homolog 1) and (Broad-Complex) were down-regulated after suppression of . JH-deficient females exhibited impaired vitellogenin expression, whereas JH exposure stimulated vitellogenin biosynthesis. Moreover, JH topical application partially rescued the decrease in vitellogenin expression in the -deficient females. These results demonstrate that brummer-mediated lipolytic system is essential for lipid mobilization and energy homeostasis during reproduction in . In addition to the classical view of brummer as a direct lipase with lipolysis activity, we propose here that brummer-mediated lipolysis works through JH signaling pathway to activate vitellogenesis and oocyte maturation that in turn regulates female fecundity.
为卵母细胞提供足够的脂质和卵黄原蛋白是卵生昆虫繁殖力不可或缺的过程。昆虫脂质储备的急性动员由Brummer（Bmm）控制，它是人类脂肪甘油三酯脂肪酶（ATGL）的直系同源物。为了研究brummer介导的脂肪分解在褐飞虱繁殖力中的功能作用，对成年雌性褐飞虱进行了针对的双链RNA（dsRNA）的RNA干扰（RNAi）分析。基因表达的敲低导致肥胖并阻断了脂肪体中的脂质动员。此外，基因沉默导致卵巢发育迟缓，卵不成熟且卵巢小管减少，产卵数量减少，产卵前期和卵期延长。此外，在基因敲低后观察到卵黄原蛋白及其受体丰度严重降低。降解保幼激素（JH）的保幼激素酯酶（juvenile hormone esterase）的转录水平上调，而在抑制后，JH受体耐甲氧普烯（Methoprene-tolerant）和泰曼（Taiman）及其下游转录因子Krüppel同源物1（Krüppel-homolog 1）和广谱复合体（Broad-Complex）的表达水平下调。缺乏JH的雌性表现出卵黄原蛋白表达受损，而JH暴露刺激卵黄原蛋白的生物合成。此外，局部应用JH部分挽救了基因缺陷型雌性中卵黄原蛋白表达的下降。这些结果表明，brummer介导的脂肪分解系统对于褐飞虱繁殖过程中的脂质动员和能量稳态至关重要。除了将brummer视为具有脂肪分解活性的直接脂肪酶的经典观点外，我们在此提出，brummer介导的脂肪分解通过JH信号通路起作用，以激活卵黄发生和卵母细胞成熟，进而调节雌性繁殖力。
