摘要
Objectives: The mosquito Anopheles gambiae is the major vector of human malaria in sub-Saharan Africa. Malaria is spread to humans through the bite of a female mosquito that has been infected by the Plasmodium parasite. While some mosquito proteins limit development of the Plasmodium parasites inside mosquitoes, the parasites have evolved to exploit mosquito proteins for successful infection. To identify those key factors, contemporary studies focus primarily on transcriptional change triggered by invasion of the mosquito midgut by Plasmodium parasites. Methods: My lab has developed different approaches to identifying genes that are regulated by post-transcriptional mechanisms in the Plasmodium-infected mosquitoes. We used sucrose density gradient centrifugation to isolate actively translating An. gambiae mRNAs on the basis of their association with polysomes. This approach led to the identification of 1,017 mosquito transcripts that were primarily regulated at the translational level 24 h after ingestion of P. falciparum-infected blood, the time at which ookinetes invade the epithelium, when compared to the uninfected controls. Results: Twenty-five immune-related genes displayed significantly increased mRNA association with polysomes in the P. falciparum-infected mosquitoes compared to uninfected controls. Transcripts of Dcr1, Dcr2, and Drosha, which are involved in small RNA biosynthesis, were found to be markedly associated with more ribosomes in the infected mosquitoes. This observation suggests that mosquito miRNAs may play important roles in the mosquito's physiological response to Plasmodium invasion. We then used CLASH(crosslinking, ligation, and sequencing of hybrids) to investigate the miRNA:mRNA interactions in the P. falciparum-infected mosquitoes. We have identified 846 miRNA-m RNA interactions in P. falciparum-infected mosquitoes and 1,845 interactions in mosquitoes fed on uninfected blood, with 432 interactions detected in both samples. These interactions involved 75 different mature miRNAs and 1,223 different protein-coding genes, including 19 putative mosquito immune genes. The identified immune genes belonged to several functional classes, including pattern recognition, signal transduction pathways, antimicrobial effectors, cell death regulators, and other effector systems, all of which are relevant to anti-Plasmodium defenses. This experiment provided a list of miRNAs that we can test immediately in the anti-Plasmodium defense. A preliminary study in our collaborator's lab has confirmed that aga-miR-305 in An.gambiae negatively regulates the anti-Plasmodium response. Injection of specific antagomir reduced aga-miR-305 abundance in vivo by over 97%, leading to a significant reduction in oocyst intensity and parasite prevalence(p<0.05). Conversely, treatment of mosquitoes with artificial aga-miR-305 mimic increased the susceptibility to P.?falciparum infection.
Objectives: The mosquito Anopheles gambiae is the major vector of human malaria in sub-Saharan Africa. Malaria is spread to humans through the bite of a female mosquito that has been infected by the Plasmodium parasite. While some mosquito proteins limit development of the Plasmodium parasites inside mosquitoes, the parasites have evolved to exploit mosquito proteins for successful infection. To identify those key factors, contemporary studies focus primarily on transcriptional change triggered by invasion of the mosquito midgut by Plasmodium parasites. Methods: My lab has developed different approaches to identifying genes that are regulated by post-transcriptional mechanisms in the Plasmodium-infected mosquitoes. We used sucrose density gradient centrifugation to isolate actively translating An. gambiae mR NAs on the basis of their association with polysomes. This approach led to the identification of 1,017 mosquito transcripts that were primarily regulated at the translational level 24 h after ingestion of P. falciparum-infected blood, the time at which ookinetes invade the epithelium, when compared to the uninfected controls. Results: Twenty-five immune-related genes displayed significantly increased mR NA association with polysomes in the P. falciparum-infected mosquitoes compared to uninfected controls. Transcripts of Dcr1, Dcr2, and Drosha, which are involved in small RNA biosynthesis, were found to be markedly associated with more ribosomes in the infected mosquitoes. This observation suggests that mosquito miRNAs may play important roles in the mosquito's physiological response to Plasmodium invasion. We then used CLASH(crosslinking, ligation, and sequencing of hybrids) to investigate the miRNA:mR NA interactions in the P. falciparum-infected mosquitoes. We have identified 846 miRNA-m RNA interactions in P. falciparum-infected mosquitoes and 1,845 interactions in mosquitoes fed on uninfected blood, with 432 interactions detected in both samples. These interactions involved 75 different mature miRNAs and 1,223 different protein-coding genes, including 19 putative mosquito immune genes. The identified immune genes belonged to several functional classes, including pattern recognition, signal transduction pathways, antimicrobial effectors, cell death regulators, and other effector systems, all of which are relevant to anti-Plasmodium defenses. This experiment provided a list of miRNAs that we can test immediately in the anti-Plasmodium defense. A preliminary study in our collaborator's lab has confirmed that aga-miR-305 in An.gambiae negatively regulates the anti-Plasmodium response. Injection of specific antagomir reduced aga-miR-305 abundance in vivo by over 97%, leading to a significant reduction in oocyst intensity and parasite prevalence(p<0.05). Conversely, treatment of mosquitoes with artificial aga-miR-305 mimic increased the susceptibility to P.?falciparum infection.
引文