The mechanisms of translational silence in the C. elegans germ line. — University of Technology
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  2. The mechanisms of translational silence in the C. elegans germ line.

The mechanisms of translational silence in the C. elegans germ line.

The mechanisms of translational silence in the C. elegans germ line.

Peter R. Boag*, Paul F. Harrison?, Adele Barugahare, Gregory Davis, Angavai Swaminathan, Ava Heinz, David R. Powell?, Traude H. Beilharz*,

Deartment of Biochemistry & Molecular Biology, Monash University, Clayton, Australia, VIC 3800.

?Victorian Bioinformatics Consortium, Monash University, Clayton, Australia, VIC 3800.

* Equal author contribution

BACKGROUND: The program of embryonic development in C. elegans is launched by activation of maternally deposited mRNA. The maternal germline is thus responsible for the transcription of at least two separate gene-expression programs: one that sustains and builds the germ cells and developing oocytes, and another that is selected and partitioned (translationally silent) for later use in the early zygote. A failure to maintain this separation of expression programs results in premature translation of regulatory factors that activate zygotic gene expression during the meiotic phase. This leads to ectopic expression of normally developmentally regulated genes and a cancerous germline. Shortening of the poly(A) tail of mRNAs is a common feature of translational repression. For stored mRNA, there-extension of the poly(A)-tail of such RNA by the cytoplasmic poly(A) RNA polymerase GLD-2, is required to activate translation. Albeit, how target mRNA are differentiated and selected for this pathway is currently unknown.

AIMS: We hypothesized that direct measure of the adenylation state of the C. elegans transcriptome in genetic mutant/knock-down strains could establish how translational silence is first achieved, and could be a useful tool to elucidate how the block to translation is released.

METHODS: We used custom RNA Sequencing to measure gene expression, poly(A)-site usage and poly(A)-tail length of the transcriptome. Our study includes transcriptomic comparison of wild-type and gld-2 mutant worms. We also examined the contribution of the 5 different worm deadenylases to initial poly(A)-tail shortening in order to understand the trigger to translational silence in this pathway.

RESUTS: More than1,000 genes show a statistically significant poly(A)-shortening in the absence of GLD-2 activity. And while no single motif appears to direct this change in adenylation state, there are overall changes to the 3’UTR sequence landscape that are strongly associated with cytoplasmic adenylation. We also unambiguously identify the silencing deadenylase in the pathway.

 

CONCLUSION: We will discuss our data in progress in terms of switches between translational silence and its activation.