messenger rnas may be targeted by short 19-27 nt rnas generally called small none-coding rnas (snrnas), the role of mirnas among other snrnas has been more studied and is well known. many researches show that all compartments of risc, proteins and mirnas take part in this wide range of regulatory impacts. ago protein homologs plus mirnas and target mrnas form a silencing complex in p-bodies whi...

One of the most efficient mechanisms by which plants protect themselves from invading virusesis the specific RNA-dependent silencing pathway termed post-transcriptional gene silencing(PTGS). In this mechanism, resistance to a virus is engineered through the expression of asegment of the virus genomein transgenic plants. Potato VirusY (PVY) is one of the mostdamaging viruses of potato, infecting...

Gene silencing via non-coding RNA, such as siRNA and miRNA, can occur at the transcriptional, post-transcriptional, and translational stages of expression. Transcriptional gene silencing (TGS) involving the RNAi machinery generally occurs through DNA methylation, as well as histone post-translational modifications, and corresponding remodeling of chromatin around the target gene into a heteroch...

BACKGROUND In plants, post-transcriptional gene silencing results in RNA degradation after transcription. Among tobacco transformants carrying a nitrate reductase (Nia) construct under the control of the cauliflower mosaic virus 35S promoter (35S-Nia2), one class of transformants spontaneously triggers Nia post-transcriptional gene silencing (class II) whereas another class does not (class I). ...

MicroRNAs (miRNAs) are small noncoding RNAs that mediate post-transcriptional gene silencing by binding to complementary target mRNAs and recruiting the miRNA-containing ribonucleoprotein complexes to the mRNAs. However, the molecular basis of this silencing is unclear. Here, we show that human Ago2 associates with the cap-binding protein complex and this association is mediated by human eIF4GI...

Small RNAs targeted to gene promoters in human cells have been shown to modulate both transcriptional gene suppression and activation. However, the mechanism involved in transcriptional activation has remained poorly defined, and an endogenous RNA trigger for transcriptional gene silencing has yet to be identified. Described here is an explanation for siRNA-directed transcriptional gene activat...

Post-transcriptional gene silencing (cosuppression) results in the degradation of RNA after transcription. A transgenic Arabidopsis line showing post-transcriptional silencing of a 35S-uidA transgene and uidA-specific methylation was mutagenized using ethyl methanesulfonate. Six independent plants were isolated in which uidA mRNA accumulation and beta-glucuronidase activity were increased up to...

Double-stranded RNA can induce the degradation of homologous RNAs in organisms as diverse as protozoa, animals, plants and fungi, resulting in post-transcriptional gene silencing. But in some species, RNA-mediated processes can also lead to translational repression, DNA methylation, heterochromatin formation or DNA elimination. In some situations, amplification of the 'trigger' double-stranded ...

Across kingdoms, RNA interference (RNAi) has been shown to control gene expression at the transcriptional- or the post-transcriptional level. Here, we describe a mechanism which involves both aspects: truncated transgenes, which fail to produce intact mRNA, induce siRNA accumulation and silencing of homologous loci in trans in the ciliate Paramecium We show that silencing is achieved by co-tran...