Specificity and mechanism of microRNAs in the regulation of gene expression

Originally thought of as a molecular inferior to its nucleic acid cousin DNA, RNA has more recently been appreciated as an equal partner in biology, a molecule at the heart of many crucial cellular reactions and perhaps the first molecule of life itself. The discovery of RNA interference (RNAi) has further emphasized the importance of RNA-based processes in the regulation of gene expression. One arm of the RNAi response uses a large class of endogenous, small RNA species termed microRNAs (miRNAs). The establishment of a mammalian tissue culture system has allowed for investigation of both the mechanism and specificity of miRNA-directed translational repression. The term RNAi can be used to encompass a wide variety of gene silencing phenomena. The canonical RNAi pathway, as first described by Fire and colleagues in C. elegans and studied biochemically in Drosophila by Tuschl, Zamore, and colleagues, is a post-transcriptional mechanism of gene silencing, in which short, interfering RNAs (siRNAs) guide the cleavage of complementary mRNAs. Endogenous miRNAs are similar to siRNAs, and the two pathways, siRNA-directed mRNA cleavage and miRNA-directed translational repression, share common protein components yet lead to different outcomes. Our results indicate that the distinct outcome of these pathways is largely determined by the interaction of the small RNA species with its mRNA target. Additionally, variation in the number of miRNA binding sites shows that miRNAs can act synergistically to enhance repression activity.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Biology.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2005

Author dc:creator

• Doench, John Gerard

Advisor dc:contributor.advisor

• Phillip A. Sharp.

• Biology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/31185

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/31185