![]() ![]() This is a previously unknown step in the RNAi-directed heterochromatin. The multiple roles of Argonautes in the RNAi effector phase and miRNA biogenesis and maturation suggest coordinate regulation of microRNA expression and function. describe a new Argonaute siRNA chaperone (ARC) that converts duplex RNA to single-stranded RNA. Two recently described Argonaute protein subfamilies mediate distinct functions in RNAi. In the classical RNAi pathway Argonaute functions as the Slicer enzyme that cleaves an mRNA target directed by a complementary siRNA. ![]() By analogy to siRNA processing, Ago2 cleavage may facilitate removal of the nicked passenger strand from RISC after maturation. In the classical RNAi pathway Argonaute functions as the Slicer enzyme that cleaves an mRNA target directed by a complementary siRNA. Argonaute is at the heart of all effector complexes in RNA interference. This endogenous, on-pathway intermediate results from cleavage of the pre-miRNA hairpin 12 nucleotides from its 3'-end. Also, we identify a role for the RISC slicer Argonaute2 (Ago2) in cleaving the pre-miRNA to an additional processing intermediate, termed Ago2-cleaved precursor miRNA or ac-pre-miRNA. Here, we show that all Argonautes elevate mature miRNA expression posttranscriptionally, independent of RNase activity. The miRNA is incorporated into the RNA-Induced Silencing Complex (RISC) with Argonaute proteins, the effector molecules in RNA interference (RNAi). In humans, Argonaute-encoding genes are phylogenetically grouped into two different clades called the Argonaute-like and the Piwi-like proteins that are, respectively, required for the miRNA and PIWI-interacting RNA (piRNA) pathways (reviewed in ( 2 )). During microRNA biogenesis, Drosha and Dicer process the primary transcript (pri-miRNA) through a precursor hairpin (pre-miRNA) to the mature miRNA. Two recently described Argonaute protein subfamilies mediate distinct functions in RNAi. The Argonautes RNA interference (RNAi) has been greatly exploited in recent years as an increasingly effective tool to study gene function by gene silencing. MicroRNAs are small endogenous noncoding RNAs involved in posttranscriptional gene regulation. Argonaute is at the heart of all effector complexes in RNA interference. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |