GATA factor translation is the final downstream step in the amino acid/target-of-rapamycin-mediated vitellogenin gene expression in the anautogenous mosquito Aedes aegypti.
Ingestion of blood is required for vector mosquitoes to initiate reproductive cycles determining their role as vectors of devastating human diseases. Nutritional signaling plays a pivotal role in regulating mosquito reproduction. Transcription of yolk protein precursor genes is repressed until mosquitoes take blood. Previously, we have shown that to signal the presence of blood in the gut, mosquitoes utilize the target-of-rapamycin (TOR) pathway. The TOR signaling pathway transduces the amino acid signal activating the major yolk protein precursor gene, vitellogenin (Vg). Here we report the identification of a GATA factor (AaGATAa) that is synthesized after a blood meal and acts as a transcriptional activator of Vg. We showed that AaGATAa bound specifically to GATA-binding sites present in the proximal promoter region of the Vg gene and positively regulated Vg expression in transfection assays. RNA interference-mediated knock down of AaGATAa transcript resulted in a significant inhibition of Vg expression in both fat-body tissue culture and blood-fed mosquitoes. AaGATAa mRNA accumulated in the fat body prior to blood feeding. However, translation of GATA was activated by blood feeding because the GATA protein increased dramatically in the fat body of blood-fed mosquitoes. This increase was also reproduced in the fat-body culture stimulated with amino acids. GATA translation was inhibited by rapamycin and cycloheximide as well as by RNA interference-mediated knock down of S6 kinase. These experiments have revealed that the TOR signaling pathway induced by nutritional signaling regulates the translation of a GATA factor, which is the specific transcriptional activator of the Vg gene.
Park
Jong-Hwa
JH
Center for Disease-Vector Research, Department of Entomology and Institute for Integrative Genome Biology, University of California, Riverside, California 92521, USA.
Attardo
Geoffrey M
GM
Hansen
Immo A
IA
Raikhel
Alexander S
AS
D000330:Aedes; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D015153:Blotting, Western; D002460:Cell Line; D002875:Chromosomes / Q000378:metabolism; D003001:Cloning, Molecular; D003513:Cycloheximide / Q000494:pharmacology; D053938:DNA Fragmentation; D004330:Drosophila / Q000378:metabolism; D050980:GATA Transcription Factors / Q000096:biosynthesis / Q000737:chemistry*; D005786:Gene Expression Regulation; D006801:Humans; D007150:Immunohistochemistry; D007763:Lac Operon; D018613:Microscopy, Confocal; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010743:Phospholipids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000378:metabolism; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012313:RNA / Q000378:metabolism; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019893:Ribosomal Protein S6 Kinases / Q000378:metabolism; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D058570:TOR Serine-Threonine Kinases; D013997:Time Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014162:Transfection; D014819:Vitellogenins / Q000096:biosynthesis*
D050980:GATA Transcription Factors; D010743:Phospholipids; D011500:Protein Synthesis Inhibitors; D012333:RNA, Messenger; D014819:Vitellogenins; D012313:RNA; D003513:Cycloheximide; D011494:Protein Kinases; C546842:MTOR protein, human; D019893:Ribosomal Protein S6 Kinases; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus