RNAi-mediated gene silencing to assess the role of synaptobrevin and cystatin in tick blood feeding
RNAi-mediated gene silencing to assess the role of synaptobrevin and cystatin in tick blood feeding
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DOI：
10.1016/j.bbrc.2005.07.036
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发表时间：
2005-09-09
影响因子：
3.1
通讯作者：
Mather, TN
中科院分区：
文献类型：
--
作者：
Karim, S;Miller, NJ;Mather, TN
除了作为病原体进入宿主的管道外，蜱唾液还含有广泛的分泌产物，有助于延长蜱的附着和吸血。蜱唾液中发现的蛋白质调节宿主止血和免疫反应。然而，目前尚不清楚蜱是否通过破坏宿主的抗原加工途径来操纵宿主的免疫反应。从唾液腺分泌到蜱唾液中的蛋白质是由于受SNARE复合物蛋白调节的囊泡膜结合颗粒物质的胞吐作用。与囊泡相关的蛋白质（v-SNARES）是胞吐过程的重要组成部分。在这项研究中，我们评估了synaptobrevin，陷阱蛋白，和半胱氨酸蛋白酶抑制剂，血液喂养成功的功能意义，在孤独的星星蜱，Amblyomma americanum，使用体内RNA干扰。在单独的实验中，通过给成年蜱注射500 ng互补每个基因序列的dsRNA来沉默蜱唾液半胱氨酸蛋白酶抑制剂和synpatobrevin基因。沉默表现为中肠和唾液腺中转录物的减少。此外，通过RNAi破坏半胱氨酸蛋白酶抑制剂和小突触泡蛋白的表达降低了蜱成功进食的能力，如进食抑制和减少的饱食重量所证明的。此外，暴露于先前暴露于半胱氨酸蛋白酶抑制剂沉默的蜱的兔的正常蜱表现出对蜱摄食的显著抗性。基于这些发现，蜱似乎通过分泌半胱氨酸蛋白酶抑制剂巧妙地逃避宿主免疫系统，半胱氨酸蛋白酶抑制剂破坏宿主抗原呈递细胞中的正常抗原加工。(c)2005年爱思唯尔公司All rights reserved.
In addition to being the conduit for pathogens into hosts, tick saliva contains a broad array of secretory products that facilitate prolonged tick attachment and blood feeding. Proteins found in tick saliva modulate host hemostasis and immune responses. However, it is not clear whether ticks manipulate the immune responses of their hosts by disrupting the antigen-processing pathways of the hosts. Protein secretion into tick saliva from the salivary glands is due to exocytosis of vesicular membrane-bound granular material regulated by SNARE complex proteins. Proteins associated with vesicles (v-SNARES) are essential components of the exocytotic process. In this study, we assessed the functional significance of synaptobrevin, a SNARE protein, and cystatin, a cysteine protease inhibitor to blood feeding success, in the lone star tick, Amblyomma americanum, using in vivo RNA interference. In separate experiments, tick salivary cystatin and synpatobrevin genes were silenced by injecting adult ticks with 500 ng of dsRNA complementing each gene sequence. Silencing was demonstrated by reduced transcript in midguts and salivary glands. Additionally, disrupting expression of cystatin and synaptobrevin by RNAi reduced the ability of ticks to feed successfully, as demonstrated by feeding inhibition and reduced engorgement weights. Moreover, normal ticks exposed to a rabbit previously exposed to cystatin-silenced ticks exhibited significant resistance to tick feeding. Based on these findings, ticks appear to skillfully evade the host immune system by secreting cystatin, which disrupts normal antigen processing in antigen-presenting cells of hosts. (c) 2005 Elsevier Inc. All rights reserved.