Mechanisms of Gene Regulation
Goeres, David C. , Sieburth, Leslie E. .
RNA decay: are mRNAs specifically targeted to 5’ vs. 3’ decay pathways?
The steady-state level of each mRNA results from a fine balance between transcription and decay. Much research on mRNA decay has focused on the role of small RNAs in regulating transcript levels. However, decay of most mRNAs does not involve small RNAs, but is instead conducted by bulk RNA decay pathways, which in plants are poorly characterized. The two major bulk mRNA decay pathways are initiated by deadenylation. Decay of the deadenylated transcripts may then proceed by exosomal degradation from the 3’ to the 5’ end of the mRNA. Alternatively, deadenylated mRNAs can be decapped, and then further decayed from the 5’ end by the XRN4 exoribonuclease. Mutant analysis indicates that both pathways are required for normal development. However, the substrate specificity of each pathway is largely unexplored. Our goal is to determine whether these two pathways are functionally redundant, or whether they are responsible for decay of separate pools of mRNAs. To address this question, we are comparing RNA decay kinetics in wild type and mRNA decapping mutants of Arabidopsis. The trident (tdt) and varicose (vcs) mutants show defects in early seedling development, and disrupt mRNA decapping. TDT encodes the mRNA decapping enzyme (DCP2); VCS encodes a scaffold required for functional assembly of the decapping complex. To assay mRNA decay rates, we treated tdt, vcs, and wild type with the transcription inhibitor cordycepin and isolated RNA at timed intervals. We then followed decay of specific mRNAs by qPCR. We have found several different patterns of mRNA decay kinetics. The loss of decapping resulted in the stabilization of some RNAs, whereas decay of other RNAs appeared to be unaffected. These data suggest that individual mRNAs may be actively targeted to specific decay pathways.
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1 - University of Utah, Department of Biology, 257 South 1400 East, Salt Lake City, UT, 84112, USA
2 - University of Utah, Department of Biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM