Regulation of Digestion in Blood-Sucking Insects

描述（由申请方提供）：在蚊子中，将血粉中的蛋白质转化为卵母细胞发育所需的卵黄蛋白和脂质是生殖周期的重要组成部分。雌性埃及伊蚊的吸血在中肠、脂肪体和卵巢中引发了一系列事件。雌蚊在短时间内摄入超过自身体重的血液，然后在接下来的36小时内将血液蛋白中的氨基酸转化为卵的成分，这一过程称为卵黄生成。这一过程始于中肠，伴随着血粉蛋白的消化，中肠消化酶合成的调节分两个阶段进行。早期阶段在进食后立即开始，并涉及翻译的激活。早期胰蛋白酶的合成可作为这一阶段的模型。晚期阶段开始于餐后6-8小时，涉及转录的激活。晚期胰蛋白酶的合成作为该阶段的模型。在这项提案中，我们寻求资金，继续研究雌蚊中肠消化酶合成的调节机制。我们提出以下两个具体目标：1。研究蛋白餐后早期胰蛋白酶mRNA翻译激活的机制。在血餐后的前30分钟内，肽或小分子存在于全身提取物中，这使得体外中肠制剂能够进行早期胰蛋白酶翻译。30分钟后，在中肠中启动磷酸化级联反应，导致早期胰蛋白酶翻译的激活。我们建议分离和表征的因素，诱导中肠的翻译能力，并表征的信号传导过程，导致激活早期胰蛋白酶翻译。我们还建议研究内质网涡在调节中肠分泌蛋白质合成的作用。2.探讨晚期胰蛋白酶基因的转录调控机制。进食后约6小时，中肠中的晚期胰蛋白酶转录开始。我们最近发现，蜕皮激素，和一个未知的因素，目前在提取物制备的脂肪体喂养蚊子，参与晚期胰蛋白酶基因诱导。我们建议的特征蜕皮激素调节晚期胰蛋白酶的表达的机制，并确定脂肪体因子和磷脂酰肌醇3-激酶（PI-3 K）信号在调制晚期胰蛋白酶转录的作用。

DESCRIPTION (provided by applicant): In mosquitoes, the conversion of protein from a blood meal into yolk proteins and lipids for the developing oocytes is an essential part of the reproductive cycle. Blood feeding by a female Aedes aegypti mosquito initiates a series of events in the midgut, the fat body and the ovaries. Female mosquitoes ingest more than their own weight in blood in a short time and then spend the next 36 hours converting the amino acids from the blood proteins into the constituents of their eggs, a process termed vitellogenesis. The process begins in the midgut with the digestions of blood meal proteins and the regulation of digestive enzyme synthesis in the midgut occurs in two phases. The early phase begins immediately after ingestion of the meal and involves activation of translation. The synthesis of early trypsin serves as a model for this phase. The late phase begins 6-8 hours after the meal and involves activation of transcription. The synthesis of late trypsin serves as a model for this phase. In this proposal we seek funds to continue work on the mechanism of regulation of digestive enzyme synthesis in the female mosquito midgut following a blood meal. We propose the following two specific aims: 1. Investigate the mechanism of activation of translation of the early trypsin mRNA following a protein meal. During the first 30 minutes following a blood meal, a peptide or small molecule is present in whole body extracts, which makes an in vitro midgut preparation competent for early trypsin translation. After 30 minutes, a phosphorylation cascade is initiated in the midgut which leads to activation of translation of early trypsin. We propose to isolate and characterize the factor that induces translational competency in the midgut, and to characterize the signaling processes that lead to activation of early trypsin translation. We also propose to investigate the role of the endoplasmic reticulum whorls in regulating secretory protein synthesis in the midgut. 2. Investigate the mechanism of transcriptional regulation of the late trypsin gene. About 6 hours after feeding, late trypsin transcription in the midgut is initiated. We have recently found that ecdysone, and an uncharacterized factor present in extracts prepared from fat bodies of fed mosquitoes, are involved in late trypsin gene induction. We propose to characterize the mechanism of ecdysone regulation of late trypsin expression, and to identify the fat body factor and the role of phosphoinositide 3-kinase (PI-3K) signaling in modulating late trypsin transcription.