Poster: Rhythms

Abs # 381: Circadian Control of mRNA Stability: Impact of dst1, a Sequence-Specific mRNA Decay Mutant

Presenter:	Accerbi, Monica , accerbi@udel.edu
Authors	Lidder, Preetmoninder  (A)   Gutierrez, Rodrigo A. (B)   Accerbi, Monica  (A)   Green, Pamela J. (A)
Affiliations:	(A): University of Delaware (B): New York University

Microarray expression data for unstable mRNAs in Arabidopsis showed that mRNA instability is associated with a group of genes controlled by the circadian clock. To investigate the relationship between mRNA stability and circadian gene expression, the stability of selected clock controlled genes (CCGs) was analyzed in Arabidopsis plants at different times of the day. Two CCGs (Ccr-like and SEN1) were found to exhibit circadian regulation of mRNA stability. In separate microarray experiments, we observed a bias among a high proportion of genes with altered expression in dst1 towards CCGs. Our data indicate that Ccr-like and SEN1, which are regulated at the level of mRNA stability by the clock, are also direct targets of the DST-mediated decay pathway. Not only were Ccr-like and SEN1 transcripts altered in their half-lives in dst1, but their stabilities were also altered in the mutant relative to the parental at different times during the day. This leads to aberrant circadian oscillation of these transcripts in the mutant demonstrating that the DST1 locus is associated with circadian control. Previous experiments (e.g. with the per gene in Drosophila) have implicated differential mRNA stability in the control of CCGs and our observations in Arabidopsis are among the first to provide direct evidence for this.