Tribolium castaneum Transformer-2 regulates sex determination and development in both males and females

Abstract

Tribolium castaneum Transformer (TcTra) is essential for female sex determination and maintenance through the regulation of sex-specific splicing of doublesex (dsx) pre-mRNA. In females, TcTra also regulates the sex-specific splicing of its own pre-mRNA to ensure continuous production of functional Tra protein. Transformer protein is absent in males and hence dsx pre-mRNA is spliced in a default mode. The mechanisms by which males inhibit the production of functional Tra protein are not known. Here, we report on functional characterization of transformer-2 (tra-2) gene (an ortholog of Drosophila transformer-2) in T. castaneum. RNA interference-mediated knockdown in the expression of gene coding for tra-2 in female pupae or adults resulted in the production of male-specific isoform of dsx and both female and male isoforms of tra suggesting that Tra-2 is essential for the female-specific splicing of tra and dsx pre-mRNAs. Interestingly, knockdown of tra-2 in males did not affect the splicing of dsx but resulted in the production of both female and male isoforms of tra suggesting that Tra-2 suppresses female-specific splicing of tra pre-mRNA in males. This dual regulation of sex-specific splicing of tra pre-mRNA ensures a tight regulation of sex determination and maintenance. These data suggest a critical role for Tra-2 in suppression of female sex determination cascade in males. In addition, RNAi studies showed that Tra-2 is also required for successful embryonic and larval development in both sexes.

Maternal provision of non‐sex‐specific transformer messenger RNA in sex determination of the wasp Asobara tabida

“…The structure of TRA2 is highly conserved and contains a RNA binding domain (RBD) flanked by two arginine/serine rich regions in all insects investigated thus far. Studies in various dipterans, the coleopteran Tribolium castaneum and the hymenopteran Apis mellifera have shown that TRA2 is necessary for female-specific tra splicing (Burghardt et al, 2005;Concha & Scott, 2009;Salvemini et al, 2009;Martín et al, 2011;Sarno et al, 2011;Nissen et al, 2012;Shukla & Palli, 2013). The activation/deactivation of tra and the tra-tra2-dsx signal-relaying pathway appears largely conserved in insects, but is governed by a large diversity in primary signals (Bopp et al, 2014).…”

The transformer2 gene of the pumpkin fruit fly, Bactrocera tau (Walker), functions in sex determination, male fertility and testis development

“…On the contrary, Btau‐tra2 was multi‐transcribed into three transcript variants instead of only one transcript as occurs with the tra2 genes of other tephritids and M. domestica (Salvemini et al, ; Sarno et al, ; Schetelig & Handler, ; Liu et al, ). To date, tra2 genes that are transcribed into multi‐transcripts have been found in other insect groups; for example, three transcripts were found to be produced in T. castaneum (Shukla & Palli, ), four in D. melanogaster , Aedes aegypti (Amrein et al, ; Liu et al, ) and N. vitripennis (Geuverink et al, ), six in Ap. mellifera and Bo.…”

Agricultural production: assessment of the potential use of Cas9-mediated gene drive systems for agricultural pest control

“…Remarkably, the genetic mechanisms that determine sex in the red flour beetle, T. casteneum, appear to be very similar to the L. cuprina regulatory hierarchy. Adapted from Scott, Pimsler, and Tarone (2014) and Shukla and Palli (2013).…”

“…Interestingly, the female-specific TcTRA protein is necessary to maintain its own production (Shukla and Palli 2012a). TcTRA-2 is necessary for the sex-specific versions of both Tcdsx and Tctra (Shukla and Palli 2013). Because of their important roles in regulating sex determination and reproduction, each of these genes could be targeted to control pest populations.…”