A Novel GATA Factor Transcriptionally Represses Yolk Protein Precursor Genes in the Mosquito Aedes aegypti via Interaction with the CtBP Corepressor

Abstract

In anautogenous mosquitoes, vitellogenesis, the key event in egg maturation, requires a blood meal. Consequently, mosquitoes are vectors of many devastating human diseases. An important adaptation for anautogenicity is the previtellogenic arrest (the state of arrest) preventing the activation of the yolk protein precursor (YPP) genes Vg and VCP prior to blood feeding. A novel GATA factor (AaGATAr) that recognizes GATA binding motifs (WGATAR) in the upstream region of the YPPgenes serves as a transcriptional repressor at the state of arrest. Importantly, AaGATAr can override the 20-hydroxyecdysone transactivation of YPP genes, and its transcriptional repression involves the recruitment of CtBP, one of the universal corepressors. AaGATAr transcript is present only in the adult female fat body. Furthermore, in nuclear extracts of previtellogenic fat bodies with transcriptionally repressed YPP genes, there is a GATA binding protein forming a band with mobility similar to that of AaGATAr. The specific repression of YPP genes by AaGATAr in the fat body of the female mosquito during the state of arrest represents an important molecular adaptation for anautogenicity.

ACKNOWLEDGMENTS

We thank T. Abel for the kind gift of (BoxA)6/CAT plasmid and pPac-ABF clones, S. Parkhurst for the GST-dCtBP clone, and K. Iatrou for antibodies to B. mori GATA. We also thank A. Hays for his invaluable help in maintaining mosquitoes, M. Trail for editing the manuscript, and D. Arnosti for helpful discussions of the manuscript.

This work was supported by grant AI-24716 from the National Institutes of Health to A. S. Raikhel. D. Martı́n was a recipient of a postdoctoral research grant from the Spanish Ministry of Education and Culture. M.-D. Piulachs was supported in part by a travel grant from the Spanish Ministry of Education and Culture.