Most female mosquitoes need to feed on vertebrate blood and use the nutrients for their own egg production. During the blood feeding, mosquitoes transmit many devastating diseases, such as malaria, dengue fever, filariasis and West Nile encephalitis. It is of great importance to study regulation of gene expression in mosquito development and reproduction to identify accessible targets that can be exploited to prevent mosquito-vectored disease transmission.
My research interest lies in elucidating the juvenile hormone signaling pathway in mosquitoes. This insect hormone affects a remarkably diverse array of processes in mosquito development and life history, including metamorphosis, reproduction, behavior, diapause, stress resistance and longevity. However, neither the receptor nor the target genes of this hormone are well characterized in the mosquito. We are currently dissecting genomic response to this hormone by means of microarray analysis in order to identify stage-specific hormone-responsive genes. We are then going to screen for transcriptional regulatory proteins that control activation of the juvenile hormone target genes. Functions of those proteins will be determined by transient RNAi assays and stable germ-line transformation of mosquitoes. This study is expected to provide a framework for understanding the juvenile hormone actions in the mosquito, which in turn may lead to development of new strategies for mosquito control.
My laboratory is also interested in signal transduction and gene regulation in mosquitoes in general, aiming at bridging genomics and proteomics. Rapid progress in mosquito genomics has allowed us to study genome-wide alteration of gene transcription in many biological events. At the same time, accumulating evidences demonstrate that expression of many mosquito genes, including the early trypsin gene and the competence factor βFTZ-F1 gene, is regulated at post-transcriptional level. We are working together with colleagues in this department to find an efficient way to assess the translational status of mosquito transcripts. This method, once established, can be adopted to identify post-transcriptionally controlled genes in mosquito development and in mosquito-parasite interactions.

Sun, G., J. Zhu, L. Chen, & A.S. Raikhel (2005) Synergistic action of E74B and ecdysteroid receptor in activating a 20-hydroxyecdysone effector gene. Proc. Natl. Acad. Sci. USA. 102:15506-11.

Chen, L., J. Zhu, G. Sun, & A.S. Raikhel (2004) The early gene Broad is involved in the ecdysteroid hierarchy governing vitellogenesis of the mosquito Aedes aegypti. J. Mol. Endocrinol. 33:743-61.

Sun, G., J. Zhu, & A.S. Raikhel (2004) The early gene E74B isoform is a transcriptional activator of the ecdysteroid regulatory hierarchy in mosquito vitellogenesis. Mol. Cell. Endocrinol. 218:95-105.

Zhu, J., L. Chen, G. Sun, & A.S. Raikhel (2006) The competence factor betaFtz-F1 potentiates ecdysone receptor activity via recruiting a p160/SRC coactivator. Mol. Cell. Biol. 26:9402-12.

Zhu, J., L. Chen, & A.S. Raikhel (2003) Posttranscriptional control of the competence factor betaFTZ-F1 by juvenile hormone in the mosquito Aedes aegypti. Proc. Natl. Acad. Sci. USA. 100:13338-43.

Zhu, J., K. Miura, L. Chen, & A.S. Raikhel (2003). Cyclicity of mosquito vitellogenic ecdysteroid-mediated signaling is modulated by alternative dimerization of the RXR homologue Ultraspiracle. Proc. Natl. Acad. Sci. USA. 100:544-9.