類補體蛋白TEP1對埃及斑蚊生殖調控之決定性影響

瘧疾、登革熱、西尼羅等病媒傳染病，至今仍對人類造成重大的危害。這些疾病每年造成全球超過三億人感染，以及至少一百萬人死亡，而臺灣在2014年也爆發嚴重的登革熱疫情，病例數總計超過15000例，對我國經濟及國民健康影響甚鉅。而多數病媒蚊傳染病並無有效藥物及疫苗，因此控制病媒蚊數量將是可行的替代策略之一，欲達到此目標，詳細探討病媒蚊生殖調控機制是第一要務。含硫脂蛋白 (thioester-containing protein, TEP) 為人類補體 C3 的同源蛋白，過去的研究發現其參與果蠅體內對抗細菌的吞噬作用 (phagocytosis)，在甘比亞瘧蚊 (Anopheles gambiae) 腸道中也扮演毒殺瘧原蟲的重要角色。此外，近期的研究也發現抑制兩個營養運輸蛋白 Lipophorin和Vitellogenin後會影響Anopheles gambiae TEP1之免疫功能，但 TEP1如何參與臺灣的重要登革病媒蚊─埃及斑蚊的生殖調控還未被深入探討。本研究利用 RNAi 的方式抑制埃及斑蚊 (Aedes aegypti) 體內TEP1的表現，發現TEP1被抑制的母蚊平均產卵量有明顯的減少，若以另一組dsRNA進行實驗結果亦然；此外，我們再利用回補實驗表現TEP1蛋白質，也發現其產卵量上升，証明此一產卵減少現象為TEP1 的專一作用。我們利用 qPCR 以及 Western blot觀察埃及斑蚊各組織中 TEP1 於吸血後的表現趨勢，結果顯示 TEP1 不論是 mRNA 或 protein 都在吸血後48-72小時的ovary 有最高表現量。有趣的是，TEP1被抑制後會影響Vitellogenin蛋白質的表現，我們發現TEP1可藉由調控Akt的磷酸化來影響Vitellogenin蛋白質的表現，另外，我們也發現TEP1的抑制會影響Vitellogenin receptor的表現。因此，綜合我們的研究結果，我們認為TEP1會藉由調控Akt來影響埃及斑蚊的產卵能力。

關鍵字

埃及斑蚊；含硫脂蛋白；生殖； RNA干擾；卵黃蛋白

並列摘要

Mosquito-borne diseases are the most devastating agents for human beings, such as malaria, dengue fever, West Nile fever…etc. The WHO reported that some 2.5 billion people are now at risk and more than a million people are killed by mosquito-borne diseases annually. More than 15,000 dengue cases were reported in Taiwan at 2014. Therefore, any possible avenue for developing novel control strategies against mosquito-borne diseases is urgently needed. Detailed investigation of mosquito reproduction should benefit the development of novel vector control strategies. TEP1 is a human complement-like protein. It plays a decisive role in fighting against invading pathogens in the mosquito. This well-defined macroglobulin-family protein has been reported to be participated in the regulation of mosquito reproduction. However, the mechanism of TEP1 in the regulation of mosquito reproduction remains unknown. In this study, silencing of TEP1 through RNA interference revealed a significant reduction of egg production in the mosquito Aedes aegypti. We conducted a rescue experiment to elucidate the effect of TEP1 in the egg production. RNA expression profile showed abundant mRNA expression of TEP1 in the ovary post blood meal. Interestingly, silencing of TEP1 leads to a reduction of vitellogenin production and this is independent of S6K phosphorylation. In addition, our data showed that silencing of TEP1 inhibited the phosphorylation of AKT, indicating that TEP1 may regulate vitellogenin production through a TOR signaling-independent pathway. Therefore, our results shed light on the essential role of TEP1 in the regulation of reproduction in the mosquito Aedes aegypti.

並列關鍵字

Aedes aegypti ； thioester-containg protein ； reproduction ； RNA interference ； Vitellogenin

參考文獻

Anders, R.F., Adda, C.G., Foley, M., and Norton, R.S. (2010). Recombinant protein vaccines against the asexual blood stages of Plasmodium falciparum. Human vaccines 6, 39-53.

Attardo, G.M., Higgs, S., Klingler, K.A., Vanlandingham, D.L., and Raikhel, A.S. (2003). RNA interference-mediated knockdown of a GATA factor reveals a link to anautogeny in the mosquito Aedes aegypti. Proceedings of the National Academy of Sciences of the United States of America 100, 13374-13379.

Bale, J.F., Jr. (2012). Emerging viral infections. Seminars in pediatric neurology 19, 152-157.

Bashan, N., Kovsan, J., Kachko, I., Ovadia, H., and Rudich, A. (2009). Positive and negative regulation of insulin signaling by reactive oxygen and nitrogen species. Physiological reviews 89, 27-71.

Blandin, S., and Levashina, E.A. (2004). Thioester-containing proteins and insect immunity. Molecular immunology 40, 903-908.

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類補體蛋白TEP1對埃及斑蚊生殖調控之決定性影響

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