Investigating Transport Mechanisms of Mitotic Spindle Localized Transcripts

• Anastasia Pashukov, Biological Sciences, Worcester Polytechnic Institute

• Jia Song, Department of Biological Sciences, University of Delaware
• Karen Hoober, Center for Bioinformatics and Computational Biology, University of Delaware

Mitosis is a fundamental and highly regulated cellular process in which a cell divides into two identical daughter cells following the replication of its DNA. A possible evolutionarily conserved mechanism to ensure that mitosis occurs in a timely manner is the transport of gene transcripts involved in mitosis to the mitotic spindle. The mitotic spindle is composed of microtubules and acts to segregate the chromosomes into the two daughter cells during mitosis. Microtubules, as well as actin filaments, are part of the cytoskeleton. A common mechanism of RNA transport is RNA-binding proteins (RBPs) binding to an RNA, allowing it to travel along the cytoskeleton with the help of motor proteins. Other RNA transport mechanisms include the involvement of lysosomes or other vesicles. I investigated the transport and spindle localization mechanisms of the transcripts Fascin, Rab35, and Gelsolin using the sea urchin as a model organism. In order to determine the exact transport mechanism for these transcripts, I incorporated both experimental and bioinformatics methods. These transcripts encode proteins which are important for the cytoskeleton and mitosis. Fascin is a protein that bundles actin filaments; Rab35 plays a crucial role in cytokinesis, the final stage of mitosis; and Gelsolin depolymerizes microtubules during mitosis. Disrupting motor proteins kinesin-1 or dynein, microtubule or actin polymerization, or global translation results in the lack of spindle localization of these transcripts, indicating that motor proteins and the cytoskeleton are necessary for the transport of these transcripts. Bioinformatics results also suggest that RBPs such as CPEB proteins could be involved in spindle localization by binding to the 3’UTR (3’ untranslated region) of these transcripts.