Increased drug and pesticide resistance has rendered many control programs for mosquito-borne diseases useless, resulting in an urgent need for new control strategies. Since malaria parasites must develop for up to two weeks in the mosquito there is opportunity to disrupt this development by enhancing mosquito innate immunity or shortening the mosquito's lifespan. The insulin/IGF-1 signaling cascade (ISC) has been shown to regulate both innate immunity and lifespan in invertebrates, and could be manipulated to reduce vector competence of mosquitoes. Based on our preliminary data, exogenous insulin and IGF-1 in the bloodmeal may also play major roles in the midgut and other tissues. To test these hypotheses, we will first determine whether exogenous human insulin and IGF-1 can stimulate the ISC in the midgut and other tissues, such as the fat body, in the mosquito Anopheles stephensi. We will also test the impact of these factors on oxidative stress and NO production, key components of aging, innate immunity, and signaling. Next we will engineer An. stephensi mosquitoes to express active forms of two ISC proteins, Akt and PTEN, in the midgut after a bloodmeal. Because AKT activates the midgut ISC and PTEN has the opposite effect, we will be able to answer three questions. 1) Does the midgut ISC regulate oxidative stress and in turn aging? 2) Does the midgut ISC affect signaling in other tissues? 3) Do changes to the ISC affect Plasmodium falciparum development? Finally, we will examine the impact of physiological levels of exogenous human insulin and IGF- 1 on the transgenic mosquitoes described above. Insulin levels in human blood can vary by as much as 10-fold after a meal and during malaria parasite infection. By understanding and taking into account the effects of this naturally occurring variation in human bloodmeals we can better predict the efficacy of Akt and PTEN overexpression on critical variables (e.g., lifespan and immunity) of vector competence. In summary, our proposed work will test both basic and applied hypotheses regarding the ISC and its impacts on mosquito physiology and vector competence that were conceptualized for Caenorhabditis elegans, Drosophila melanogaster and mammals. In addition, our work offers a different approach to the transgenic modification of mosquitoes to limit their vectorial capacity. Relevance: Many mosquito-borne disease agents, including malaria parasites, dengue virus, and West Nile virus, must develop in mosquitoes for extended periods before being transmitted to humans. We hope to enhance innate immunity and/or reduce average lifespan of a model mosquito below this development period so that transmission of malaria parasites is reduced or eliminated.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
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Special Emphasis Panel (ZRG1-IDM-M (02))
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Costero, Adriana
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University of Arizona
Schools of Earth Sciences/Natur
United States
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Drexler, Anna L; Pietri, Jose E; Pakpour, Nazzy et al. (2014) Human IGF1 regulates midgut oxidative stress and epithelial homeostasis to balance lifespan and Plasmodium falciparum resistance in Anopheles stephensi. PLoS Pathog 10:e1004231
Pietri, J E; Cheung, K W; Luckhart, S (2014) Knockdown of mitogen-activated protein kinase (MAPK) signalling in the midgut of Anopheles stephensi mosquitoes using antisense morpholinos. Insect Mol Biol 23:558-65
Luckhart, Shirley; Giulivi, Cecilia; Drexler, Anna L et al. (2013) Sustained activation of Akt elicits mitochondrial dysfunction to block Plasmodium falciparum infection in the mosquito host. PLoS Pathog 9:e1003180
Drexler, Anna; Nuss, Andrew; Hauck, Eric et al. (2013) Human IGF1 extends lifespan and enhances resistance to Plasmodium falciparum infection in the malaria vector Anopheles stephensi. J Exp Biol 216:208-17
Hauck, Eric S; Antonova-Koch, Yevgeniya; Drexler, Anna et al. (2013) Overexpression of phosphatase and tensin homolog improves fitness and decreases Plasmodium falciparum development in Anopheles stephensi. Microbes Infect 15:775-87
Pakpour, Nazzy; Corby-Harris, Vanessa; Green, Gabriel P et al. (2012) Ingested human insulin inhibits the mosquito NF-?B-dependent immune response to Plasmodium falciparum. Infect Immun 80:2141-9
Surachetpong, Win; Pakpour, Nazzy; Cheung, Kong Wai et al. (2011) Reactive oxygen species-dependent cell signaling regulates the mosquito immune response to Plasmodium falciparum. Antioxid Redox Signal 14:943-55
Pon, Jennifer; Napoli, Eleonora; Luckhart, Shirley et al. (2011) Mitochondrial NAD+-dependent malic enzyme from Anopheles stephensi: a possible novel target for malaria mosquito control. Malar J 10:318
Marquez, Alexander G; Pietri, Jose E; Smithers, Hannah M et al. (2011) Insulin-like peptides in the mosquito Anopheles stephensi: identification and expression in response to diet and infection with Plasmodium falciparum. Gen Comp Endocrinol 173:303-12
Pakpour, Nazzy; Cheung, Kong Wai; Souvannaseng, Lattha et al. (2010) Transfection and mutagenesis of target genes in mosquito cells by locked nucleic acid-modified oligonucleotides. J Vis Exp :