Poster: Posttranscriptional Regulation

Abs # 1074: Towards understanding the mechanisms for RNA localization in the giant unicell Acetabularia acetabulum

Presenter:	Henry, Isabelle M., henryi@u.washington.edu
Authors	Henry, Isabelle M. (A)   Wilkinson, Mark D. (B)   Grotewold, Erich  (C)   Mandoli, Dina F. (D)
Affiliations:	(A): Biology Department, University of Washington, Seattle 98195 (B): Founder, Illuminae Media, Saskatoon, Sk, Canada (C): Department of Plant Biology and Plant Biotechnology Center, OHIO State University, Columbus, 43210 (D): Department of Biology and Center for Developmental Biology, University of Washington, Seattle 98195

Messenger RNA molecules localized to the cytoplasm were first identified 20 years ago. Since then, about 100 localized transcripts have been described in a variety of animal cells and in yeast, suggesting that this process might be common to all eukaryotes. Basic features of mRNA localization that may be conserved across eukaryotes include cis-acting elements (“zipcodes”) that targets an mRNA to a subcellular region, a protein-RNA complex as the “vehicle”, and the cytoskeleton that acts as a “road” for RNA movement. Messenger RNA localization is also essential in plant and algae but less than 20 localized transcripts have been documented to date (2 in two plant species and 10 in two algal species). Evidence suggests that intracellular transport uses different cytoskeletal elements in plant and animal cells. Acetabularia acetabulum is an outstanding model for elucidating mRNA localization in photosynthetic organisms. This giant green alga is a highly polarized unicell: growth occurs almost exclusively at the apex yet the single diploid nucleus resides in the rhizoid, centimeters away. We believe that Acetabularia relies on mRNA localization to regulate gene expression, establish and maintain polarity and perform morphogenesis. More than half (9 of the 16) mRNAs examined to date are localized to one or the other end of the unicell, giving credence to this hypothesis. We have created two subtracted EST libraries from Acetabularia and randomly sequenced 1,000 clones. We are currently using a combination of micro-array analysis and bioinformatics to identify localized transcripts in this unicell and search for zipcodes, directing their localization. We will present our latest findings at this meeting.