Molecular Basis of Ecdysteroid Action in the Mosquito

摘要： 嗜血的雌性蚊子在进食的同时传播许多毁灭性的疾病 人血。足够大的血量对于雌性卵子的发育是必不可少的 蚊子，从而将繁殖、采血和病原体传播联系在一起。因此， 对调控卵子发育的分子机制的清楚理解可以起到 在改进蚊子控制方法方面发挥关键作用。在埃及伊蚊中，登革热--寨卡-- 和传播黄热病的蚊子，两种主要的昆虫激素-保幼激素(JH) 和20-羟基蜕皮酮(20E)，控制两相雌性蚊子的繁殖周期。这个 羽化后(PE)或卵黄形成前成熟阶段受JH，a 倍半萜。然而，血餐后(Pbm)或卵黄形成阶段主要是 由蜕皮激素控制，20E。JH作用的分子基础的某些方面已经被 最近才破译出来的。然而，对中间因素在经济增长中的作用的研究 JH/Met的监管级联正在进行中。在大多数情况下，JH的基因激活是由 耐甲基丁二烯(Met)JH受体的直接DNA结合。然而，镇压 JH的作用机制是通过中间因素间接作用的。这项提议的目的是进一步 阐明JH介导的基因激活和抑制级联反应。对角色的调查 Krüppel同系物1(Kr-H1)，作为Met的下游因子，介导基因抑制，以及 它与远程抑制因子毛发的合作作用将是主要焦点之一。这个 建议对JH途径靶基因的染色质景观进行比较分析 确定蛋氨酸、毛发和Kr-H1等组分对染色质的贡献 目标基因的状态。大多数关于20E作用机制的研究都集中在 通过蜕皮激素受体(ECR)进行正基因调控。这项建议，主要是针对 破译20E和ECR在之前未被探索的基因负调控区域中的作用， 在卵黄形成时期。我们计划阐明直接否定和间接否定的机制 调控和鉴定20E/ECR介导基因的辅阻遏子(S)和中间因子(S) 抑制途径。这项研究可能会导致识别目标，这些目标可以是 被阻止或转化以实现雌性蚊子的生殖控制，从而控制 进食血液和传播病原体。

Abstract: Hematophagous female mosquitoes transmit numerous devastating diseases, while feeding on human blood. A large enough blood-meal is essential for the development of eggs in a female mosquito, thereby interlinking reproduction, blood-feeding and pathogen transmission. Therefore, a clear understanding of the molecular mechanisms regulating egg development can play a critical role in advancement of mosquito control methods. In Aedes aegypti, the Dengue-, Zika- and Yellow fever- transmitting mosquito, two major insect hormones - the juvenile hormone (JH) and the 20-hydroxyecdysone (20E), control the biphasic female mosquito reproductive cycle. The post eclosion (PE) or the pre-vitellogenic maturation phase is under the control of JH, a sesquiterpenoid. Whereas, the post blood meal (PBM) or the vitellogenic phase is mostly controlled by the ecdysteroid, 20E. Some aspects of the molecular basis of JH action has been deciphered in recent times. However, studies on the role of the intermediate factors within the JH/Met regulatory cascade, are ongoing. Gene activation by JH, in most cases, is mediated by direct DNA binding of the JH-receptor Methoprene-tolerant (Met). However, the repression mechanism by JH is indirect, through intermediate factors. This proposal is aimed towards further elucidation of the JH mediated gene activation and repression cascades. Investigation of the role of Krüppel homolog 1(Kr-h1), as a downstream factor of Met in mediating gene repression, and its cooperative action with the long-range repressor Hairy, will be one of the primary foci. The proposed comparative analysis of the chromatin landscapes of JH pathway target genes, should determine the contributions of the components such as Met, Hairy and Kr-h1, on the chromatin states of the target genes. Most studies, on the mechanism of 20E action, have focused on positive gene regulation through the Ecdysone Receptor (EcR). This proposal, is aimed mainly at deciphering the role of 20E and EcR in the previously unexplored area of negative gene regulation, during the vitellogenic period. We plan to elucidate the mechanism of direct and indirect negative regulation and identify co-repressor(s) and intermediate factor(s) of the 20E/EcR-mediated gene repression pathway. This study should potentially lead to identification of targets that can either be blocked or transformed to achieve reproductive control in female mosquitoes, thereby reining blood feeding and pathogen transmission.