Transposable elements (TEs) are DNA sequences that can change their position within a genome. In the germline of arthropods, post-transcriptional regulation of TE expression is mainly mediated by the Piwi-interacting RNA (piRNA) pathway. piRNAs are small RNAs of 24-30 nucleotides (nt) in length produced from genomic precursor transcripts as well as through a ‘ping-pong' amplification cycle. In somatic tissues, certain insects, such as Drosophila, instead rely on the small interfering RNA (siRNA) pathway as a key regulator of TE expression. siRNAs are 21-nt small RNAs produced from double-stranded RNA by the endonuclease Dicer2, which guides an RNA-induced silencing complex to degrade a target RNA. However, whether the siRNA pathway also regulates TE expression in the mosquito Aedes aegypti, a medically important vector species with abundant somatic piRNAs, is unknown.
To address this question, we investigated the expression of TEs and small RNAs in both somatic and gonadal tissues of a Dicer2 mutant line of Ae. aegypti and its wild-type counterpart. Our results show a modified pattern of TE expression and a decrease in TE-derived 21-nt small RNAs in the Dicer2 mutant line. Despite that, no major shift of TE transcript abundance is observed, nor any compensation by increased piRNA pathway activity. Interestingly, the lack of a functional siRNA pathway also causes perturbations in ping-pong activity and the expression of certain piRNA-associated genes.
In conclusion, the mosquito Ae. aegypti produces siRNAs targeting TEs but these lack a critical role in the regulation of TE expression both in somatic and in gonadal tissues. Whether the lack of Dicer2 affects TE activity remains to be studied.
| Subject : | : | poster |
| Topics | : | Transposable Element Control and Epigenetics |
| Keywords | : | yellow fever ; mosquito ; small RNA ; RNAseq ; pingpong cycle ; piRNA ; Dicer2 |
| PDF version | : |  PDF version |
