Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721, USA.
Proc Natl Acad Sci U S A. 2011 Jun 14;108(24):E211-7. doi: 10.1073/pnas.1102637108. Epub 2011 May 31.
Blood feeding by vector mosquitoes provides the entry point for disease pathogens and presents an acute metabolic challenge that must be overcome to complete the gonotrophic cycle. Based on recent data showing that coatomer protein I (COPI) vesicle transport is involved in cellular processes beyond Golgi-endoplasmic reticulum retrograde protein trafficking, we disrupted COPI functions in the Yellow Fever mosquito Aedes aegypti to interfere with blood meal digestion. Surprisingly, we found that decreased expression of the γCOPI coatomer protein led to 89% mortality in blood-fed mosquitoes by 72 h postfeeding compared with 0% mortality in control dsRNA-injected blood-fed mosquitoes and 3% mortality in γCOPI dsRNA-injected sugar-fed mosquitoes. Similar results were obtained using dsRNA directed against five other COPI coatomer subunits (α, β, β', δ, and ζ). We also examined midgut tissues by EM, quantitated heme in fecal samples, and characterized feeding-induced protein expression in midgut, fat body, and ovary tissues of COPI-deficient mosquitoes. We found that COPI defects disrupt epithelial cell membrane integrity, stimulate premature blood meal excretion, and block induced expression of several midgut protease genes. To study the role of COPI transport in ovarian development, we injected γCOPI dsRNA after blood feeding and found that, although blood digestion was normal, follicles in these mosquitoes were significantly smaller by 48 h postinjection and lacked eggshell proteins. Together, these data show that COPI functions are critical to mosquito blood digestion and egg maturation, a finding that could also apply to other blood-feeding arthropod vectors.
吸血的病媒蚊为病原体提供了进入点，并带来了急性代谢挑战，必须克服这些挑战才能完成生殖周期。基于最近的数据表明，衣壳蛋白 I (COPI) 囊泡运输参与了高尔基体-内质网逆行蛋白运输以外的细胞过程，我们干扰了黄热病蚊埃及伊蚊中的 COPI 功能，以干扰血餐消化。令人惊讶的是，我们发现与对照 dsRNA 注射的吸血蚊子相比，γCOPI 衣壳蛋白表达降低导致 72 小时后 89%的吸血蚊子死亡，而对照 dsRNA 注射的吸血蚊子为 0%，γCOPI dsRNA 注射的吃糖蚊子为 3%。使用针对其他五个 COPI 衣壳蛋白亚基（α、β、β'、δ 和 ζ）的 dsRNA 也获得了类似的结果。我们还通过 EM 检查了中肠组织，定量了粪便中的血红素，并对 COPI 缺陷蚊子的中肠、脂肪体和卵巢组织中的进食诱导蛋白表达进行了特征分析。我们发现 COPI 缺陷破坏了上皮细胞膜的完整性，刺激了过早的血餐排泄，并阻断了几种中肠蛋白酶基因的诱导表达。为了研究 COPI 运输在卵巢发育中的作用，我们在吸血后注射了 γCOPI dsRNA，发现尽管血液消化正常，但这些蚊子的卵泡在注射后 48 小时明显变小，并且缺乏卵壳蛋白。这些数据表明，COPI 功能对于蚊子的血液消化和卵成熟至关重要，这一发现也可能适用于其他吸血节肢动物媒介。
