GATA transcription, translation and regulation in Haemaphysalis longicornis tick: Analysis of the cDNA and an essential role for vitellogenesis

Blood feeding tightly regulates the reproductive cycles of ticks. Vitellogenesis and nutritional signaling are key events in the tick reproductive cycle. Here we report the identification of a GATA factor that is synthesized after a blood meal and acts as a transcriptional activator of vitellogenin (Vg), and the identification of an S6 kinase that is a transcription regulator of the amino acid signaling pathway. Tick GATA mRNA accumulated in the midgut prior to blood feeding. However, translation of GATA was activated by blood feeding because the GATA protein dramatically increased in the fat body of engorged females. RNA interference-mediated knockdown of S6 kinase and GATA factor revealed the involvements of S6 kinase in GATA activation and resulted in a significant inhibition of the major yolk protein vitellogenin in engorged ticks and effectively disrupting egg development after a blood meal. These results indicate that the GATA factor, a specific transcriptional activator of Vg gene, represents an important molecule for the regulation of tick vitellogenesis and reproduction.