A truncated form of a transcription factor Mamo activates vasa in Drosophila embryos

Abstract

Expression of the vasa gene is associated with germline establishment. Therefore, identification of vasa activator(s) should provide insights into germline development. However, the genes sufficient for vasa activation remain unknown. Previously, we showed that the BTB/POZ-Zn-finger protein Mamo is necessary for vasa expression in Drosophila. Here, we show that the truncated Mamo lacking the BTB/POZ domain (MamoAF) is a potent vasa activator. Overexpression of MamoAF was sufficient to induce vasa expression in both primordial germ cells and brain. Indeed, Mamo mRNA encoding a truncated Mamo isoform, which is similar to MamoAF, was predominantly expressed in primordial germ cells. The results of our genetic and biochemical studies showed that MamoAF, together with CBP, epigenetically activates vasa expression. Furthermore, MamoAF and the germline transcriptional activator OvoB exhibited synergy in activating vasa transcription. We propose that a Mamo-mediated network of epigenetic and transcriptional regulators activates vasa expression.

Expression of the core promoter factors TATA box binding protein and TATA box binding protein‐related factor 2 in Drosophila germ cells and their distinct functions in germline development

“…OvoB overexpression alone resulted in a severe rough eye phenotype, whereas the overexpression of both MamoAF and OvoB resulted in a lethal phenotype of flies raised at 30℃ (Figure 1e). This lethal phenotype suggests that MamoAF interacts genetically with OvoB, which is consistent with previous results showing physical interactions between them (Nakamura et al, 2019).…”

“…We previously reported that MamoAF collaborates with CBP to activate vas expression (Nakamura et al, 2019). Therefore, we further examined the genetic interaction between MamoAF and CBP using the MamoAF-induced rough eye phenotype.…”

“…Dcr-2 nos-Gal4 (BL25751), and UAS-HDAC1 (BL32241) were obtained from the Bloomington Stock Center. UASp-MamoAF has been described previously (Nakamura et al, 2019). nos-Gal4 was a gift from Dr. (Nakamura et al, 2019) was used to generate UASt-MamoAF flies by standard injection protocols.…”

“…UASp-MamoAF has been described previously (Nakamura et al, 2019). nos-Gal4 was a gift from Dr. (Nakamura et al, 2019) was used to generate UASt-MamoAF flies by standard injection protocols. All stocks were maintained at 25°C or at room temperature in standard Drosophila medium unless otherwise noted.…”

“…Overexpression of N‐terminal truncated Mamo (MamoAF) lacking the BTB/POZ domain, but having the C 2 H 2 Zn‐finger domains, strongly promotes vas expression. Furthermore, we identified that Mamo mRNA encoding a truncated Mamo isoform, which is similar to MamoAF, is predominantly expressed in PGCs (Nakamura et al., 2019). Therefore, these results suggest that the short Mamo lacking the BTB/POZ domain is a potent vas activator.…”