PUBLICATION

Translational inhibition by deadenylation-independent mechanisms is central to microRNA-mediated silencing in zebrafish

Authors

Mishima, Y., Fukao, A., Kishimoto, T., Sakamoto, H., Fujiwara, T., and Inoue, K.

ID

ZDB-PUB-120111-40

Date

2012

Source

Proceedings of the National Academy of Sciences of the United States of America 109(4): 1104-1109 (Journal)

Registered Authors

Inoue, Kunio, Kishimoto, Tomoyoshi, Mishima, Yuichiro

Keywords

none

MeSH Terms

MicroRNAs/metabolism
MicroRNAs/physiology*
Zebrafish Proteins/genetics*
Zebrafish Proteins/metabolism
RNA Stability/physiology*
Luciferases
Blotting, Western
Amino Acid Motifs/genetics
Mutagenesis, Site-Directed
Autoantigens/genetics*
Autoantigens/metabolism
Gene Expression Regulation, Developmental/physiology*
Gene Silencing/physiology*
Models, Biological*
Real-Time Polymerase Chain Reaction
In Situ Hybridization
Animals
Zebrafish/embryology*
Zebrafish/metabolism
Green Fluorescent Proteins/metabolism

PubMed

22232654 Full text @ Proc. Natl. Acad. Sci. USA

Abstract

MicroRNA (miRNA) is a class of small noncoding RNA approximately 22 nt in length. Animal miRNA silences complementary mRNAs via translational inhibition, deadenylation, and mRNA degradation. However, the underlying molecular mechanisms remain unclear. A key question is whether these three outputs are independently induced by miRNA through distinct mechanisms or sequentially induced within a single molecular pathway. Here, we successfully dissected these intricate outputs of miRNA-mediated repression using zebrafish embryos as a model system. Our results indicate that translational inhibition and deadenylation are independent outputs mediated by distinct domains of TNRC6A, which is an effector protein in the miRNA pathway. Translational inhibition by TNRC6A is divided into two mechanisms: PAM2 motif-mediated interference of poly(A)-binding protein (PABP), and inhibition of 52 cap- and poly(A) tail-independent step(s) by a previously undescribed P-GL motif. Consistent with these observations, we show that, in zebrafish embryos, miRNA inhibits translation of the target mRNA in a deadenylation- and PABP-independent manner at early time points. These results indicate that miRNA exerts multiple posttranscriptional outputs via physically and functionally independent mechanisms and that direct translational inhibition is central to miRNA-mediated repression.

Genes / Markers

Figures