Distinct function of Aedes aegypti MMP1 in the regulation of vitellogenesis and development

• Main Authors: Chia-Yu Lai, 賴佳妤
• Other Authors: Shin-Hong Shiao 蕭信宏
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/55216227014761792156

碩士 === 國立臺灣大學 === 微生物學研究所 === 99 === Matrix Metalloproteinases (MMPs) are a family of enzymes that play major roles in tissue remodeling, such as embryonic growth, development, reproductive process and wound healing in mammals. In addition, deregulation production of these endopeptidases is associated with a number of pathological conditions resulting in the activation of innate immune responses. To date, more than 20 human MMPs have been identified and characterized and only two homologues are identified in the fruit fly Drosophila melanogaster. In spite of the intensive investigation in mammals and fruit fly, functional roles of MMP family in the mosquito are largely unknown. Recently, we identified six MMPs in the mosquito Aedes aegypti, the major vector of dengue virus. All of these MMPs contain a highly conserved catalytic domain and show signal peptide at the N-terminal part. The transcriptional and translational expression pattern of Ae. aegypti MMP1 (AaMMP1) were examined by quantitative Real-Time PCR and Western blot analysis, respectively. AaMMP1 mRNA is highly expressed at white pupal stage and 3 days post eclosion, whereas AaMMP1 protein is only expressed at 6 and 12 hours after a blood meal. In addition, AaMMP1 is highly expressed at fatbody and midgut after a blood meal. Next, we applied the well established reverse genetic approach by silencing specific MMPs in the mosquitoes to characterize the functions of MMPs. Silence of AaMMP1 by intrathoracically introduced the double-stranded RNA targeted to AaMMP1 revealed that oviposition rate is reduced in the absence of AaMMP1. Surprisingly, silence of Frizzled (Fz), a component of Wnt signaling, prior to blood meal resulted in the complete inhibition of AaMMP1. In addition, we showed that silence of AaTOR and AaFz completely inhibit the expression of AaMMP1 in the in vitro fat body culture. RNAi-mediated silence of the key component in the IMD pathway resulted in the depletion of AaMMP1 in vivo. Taken together, our results demonstrated the crucial role of AaMMP1 in the mosquito vitellogenesis and development, and the multiple regulatory machinery by different signal transduction pathways.