Wolbachia-induced transcription factor GATA4 suppresses ovary-specific genes blastoderm-specific protein 25D and imaginal disc growth factor S. Osei-Amo*, M. Hussein*¶, S. Asad*, L. Hugo† and S. Asgari* *Australian Infectious Disease Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, Queensland, Australia; and †QIMR Berghofer Medical Research Institute, Royal Brisbane Hospital, Brisbane, Queensland, Australia Abstract The endosymbiotic bacterium Wolbachia infects a wide array of insect hosts and has been implicated in a range of biological modifications as a consequence of its infection. Previously, it was shown that the tran- scription factor GATA4 was significantly induced in Wolbachia wMelPop-CLA strain infected Aedes aegypti whole mosquitoes and cells. Here, we provide evidence that this induction also occurs in mosquito ovaries where the ovary-specific genes blastoderm- specific protein 25D (Bsg25D) and imaginal disc growth factor (Disc) are suppressed by Wolbachia. We further demonstrate that transcriptional depletion of GATA4 results in upregulation of both genes and conversely its overexpression leads to downregula- tion of the genes, suggesting that Wolbachia-induced GATA4 plays a suppressive regulatory role with regards to Bsg25D and Disc expression in mosquito ovaries. When the Disc gene was silenced in mosqui- toes, we did not observe any difference in the number of mature ovarian follicles developed between treat- ment groups. However, we did find a significant delay in the hatching of eggs that had been laid by Disc knockdown mosquitoes. Keywords: Aedes aegypti, GATA4, Wolbachia, ovary. Introduction Wolbachia pipientis is an endosymbiotic bacterium that is estimated to have infected as many as two thirds of all insect species (Jiggins et al., 2001; Hilgenboecker et al., 2008). Wolbachia is most commonly associated with manipulating host reproductive strategies through means such as feminization, male killing and cytoplasmic incom- patibility (Bourtzis & O’Neill, 1998; Werren et al., 2008), although some strains of the Gram-negative bacterium have been known to have mutualistic interactions with their hosts (Fry et al., 2004; Alexandrov et al., 2007). These phenotypic changes in particular are likely to be related to Wolbachia’s propensity for colonization of the gonads (Cheng et al., 2000; Beckmann et al., 2013; Jiang et al., 2014), where it supposedly can make changes to these organs in order to augment its ability to be trans- mitted vertically and persist in host populations. Despite being crucial for Wolbachia’s establishment in host popu- lations, relatively little is known about the precise tran- scriptional changes that facilitate these physiological modulations. Given Wolbachia’s unique ability to inhibit replication of several pathogens, including dengue virus (DENV) (Moreira et al., 2009; Glaser & Meola, 2010; Hughes et al., 2011), it represents an exciting, novel bio- logical vector control avenue for implementation in areas in which DENV and other arboviruses are endemic. Despite showing some recent success, establishment of some non-native Wolbachia strains in clinically significant vector hosts have met with challenges associated with the reduced fitness associated with Wolbachia infection (Nguyen et al., 2015). One important factor in this regard may be the reduced fecundity that results from infection with Wolbachia (McMeniman et al., 2011; Caragata et al., 2014). Little is known about which aspects of Wolbachia- Correspondence: Sassan Asgari, Australian Infectious Disease Research Centre, School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia. Tel./fax: 1617-33652043; e-mail: s.asgari@uq.edu.au ¶Present address: Mazhar Hussein, School of Biomedical Sciences, Institute of Health and Biomedical Innovation, Queensland University of Technology, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia V C 2018 The Royal Entomological Society 1 Insect Molecular Biology (2018) 00(00), 00–00 doi: 10.1111/imb.12371