RNA-Mediated Gene Regulation in Drosophila
Harsh H. Kavi, Harvey R. Fernandez, Weiwu Xie and James A. Birchler
from: RNA and the Regulation of Gene Expression: A Hidden Layer of Complexity (Edited by: Kevin V. Morris). Caister Academic Press, U.K. (2008)
Short RNAs are increasingly recognized to play multiple roles in affecting gene expression at many levels as illustrated by work in Drosophila. Here we review the biochemical parameters of RNA interference, the technique that uses double stranded RNA, which is cleaved by Dicer to produce small interfering RNAs (siRNAs), as guides to cleave homologous mRNAs. This process is believed to occur in the cytoplasm and is used in the endogenous process of viral resistance. In addition, many of the same gene products are also involved in transcriptional gene silencing processes. This was first documented for cosuppression of white-Alcohol dehydrogenase transgenes, which is associated with the Polycomb repressive complex of chromatin proteins. Genetic studies of RNA silencing genes also implicate a role in heterochromatin silencing. Some gene products involved in RNAi are also involved in the formation of repeat associated small RNAs (rasiRNAs), whose formation appears to be Dicer independent and critical for repressing transposon expression particularly in the germline. Roles for small RNAs are also implicated in chromatin insulator activity, the integrity of the nucleolus and long-range associations of homeotic genes read more ...