title: PABP is not essential for microRNA-mediated translational repression and deadenylation in vitro.
abstract: MicroRNAs silence their complementary target genes via formation of the RNA-induced silencing complex (RISC) that contains an Argonaute (Ago) protein at its core. It was previously proposed that GW182, an Ago-associating protein, directly binds to poly(A)-binding protein (PABP) and interferes with its function, leading to silencing of the target mRNAs. Here we show that Drosophila Ago1-RISC induces silencing via two independent pathways: shortening of the poly(A) tail and pure repression of translation. Our data suggest that although PABP generally modulates poly(A) length and translation efficiency, neither PABP function nor GW182-PABP interaction is a prerequisite for these two silencing pathways. Instead, we propose that each of the multiple functional domains within GW182 has a potential for silencing, and yet they need to act together in the context of full-length GW182 to exert maximal silencing.
authors: Institute of Molecular and Cellular Biosciences, University of Tokyo, Bunkyo-ku, Tokyo, Japan.
authors: Takashi
authors: T
authors: Fukaya
authors: Yukihide
authors: Y
authors: Tomari
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000378:metabolism*; D002460:Cell Line; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000378:metabolism*; D020868:Gene Silencing; D035683:MicroRNAs / Q000378:metabolism*; D039102:Poly(A)-Binding Proteins / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000235:genetics*; D034743:RNA-Induced Silencing Complex / Q000378:metabolism*
chemical_list: C489654:AGO1 protein, Drosophila; D060565:Argonaute Proteins; D029721:Drosophila Proteins; C513405:Gw protein, Drosophila; D035683:MicroRNAs; D039102:Poly(A)-Binding Proteins; D034743:RNA-Induced Silencing Complex