Regulatory mechanisms of chitin biosynthesis and roles of chitin in peritrophic matrix formation in the midgut of adult Aedes aegypti
Regulatory mechanisms of chitin biosynthesis and roles of chitin in peritrophic matrix formation in the midgut of adult Aedes aegypti
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DOI：
10.1016/j.ibmb.2005.09.003
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发表时间：
2006-01-01
影响因子：
3.8
通讯作者：
Christensen, BM
中科院分区：
文献类型：
--
作者：
Kato, N;Mueller, CR;Christensen, BM
在蚊子中，围食基质是响应于血液喂养而形成的，并且当与血粉一起摄入的病原体试图到达并穿过中肠上皮时，围食基质可以是物理屏障。围食基质的主要成分是含有几丁质结合结构域的蛋白质、糖基化蛋白质和几丁质原纤维。甲壳素是由果糖-6-磷酸通过一系列的五个酶促反应合成的。我们以前发现，血液喂养诱导转录上调谷氨酰胺：果糖-6-磷酸酰胺转移酶-I（AeGfat-I）和几丁质合成酶（AeCs），生物合成途径的第一个和最后一个酶，分别在埃及伊蚊中肠。在这项研究中，我们证明了围食基质的形成被破坏时，任何一个基因的转录丰度敲低使用RNAi方法。我们还表明，重组AeGFAT-1的酶活性对UDP-N-乙酰葡糖胺（几丁质合成酶的底物）的反馈抑制敏感。这些结果表明，在中肠的Ae。（1）几丁质响应于血液进食而从头合成，并且是围食基质的必需组分，和（2）几丁质生物合成部分地通过AeGFAT-1对UDP-N-乙酰葡糖胺的抑制敏感性而负调节。(C)2005爱思唯尔有限公司保留所有权利。
In mosquitoes, the peritrophic matrix is formed in response to blood feeding and can be a physical barrier when pathogens ingested with blood meal attempt to reach and transverse the midgut epithelium. The main components of the peritrophic matrix are chitin-biding-domain containing proteins, glycosylated proteins, and chitin fibrils. Chitin is synthesized from fructose-6-phosphate by a series of five enzymatic reactions. We previously found that blood feeding induces transcriptional up-regulation of glutamine: fructose-6-phosphate amidotransferase-I (AeGfat-I) and chitin synthase (AeCs), the first and last enzymes of the biosynthetic pathway, respectively, in the midgut of Aedes aegypti. In this study, we demonstrated that formation of the peritrophic matrix is disrupted when the transcript abundance of either gene is knocked-down using RNAi methodologies. We also have shown that enzymatic activity of recombinant AeGFAT-1 is sensitive to feedback inhibition by UDP-N-acetylglucosamine, a Substrate of chitin synthase. These findings demonstrate that in the midgut of adult Ae. aegypti, (1) chitin is synthesized de novo in response to blood feeding and is an essential component of the peritrophic matrix, and (2) chitin biosynthesis is negatively regulated, in part, by inhibitory sensitivity of AeGFAT-1 to UDP-N-acetylglucosamine. (C) 2005 Elsevier Ltd. All rights reserved.