Published in: Cell, vol. 121, no. 2, pp. 223-234 (22 April 2005) http://www.cell.com/content/article/abstract?uid=PIIS0092867405001613 _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ "A Rae1-Containing Ribonucleoprotein Complex Is Required for Mitotic Spindle Assembly". Michael D. Blower 1, 2, Maxence Nachury 1, 2, 3, Rebecca Heald^ 1, *, and Karsten Weis 1, * 1 Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California 94720 * Correspondence: Rebecca Heald Ph: 510-643-5493; F: 510-642-8620 [R.H.] heald@socrates.berkeley.edu * Correspondence: Karsten Weis Ph: 510-643-0407; F: 510-643-6791 [K.W.] kweis@berkeley.edu 2 These authors contributed equally to this work. 3 Present address: Department of Pathology, Stanford University School of Medicine, Palo Alto, California 94305. _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Abstract: Centrosome-independent microtubule polymerization around chromosomes has been shown to require a local gradient of RanGTP, which discharges mitotic cargoes from the nuclear import receptor importin b. Here, we have used an activity-based assay in Xenopus egg extracts to purify the mRNA export protein Rae1 as a spindle assembly factor regulated by this pathway. Rae1 is a microtubule-associated protein that binds directly to importin b. Depletion of Rae1 from extracts or cells severely inhibits mitotic spindle assembly. A purified Rae1 complex stabilizes microtubules in egg extracts in a RanGTP/importin b-regulated manner. Interestingly, Rae1 exists in a large ribonucleoprotein complex, which requires RNA for its activity to control microtubule dynamics in vitro. Furthermore, we provide evidence that RNA associates with the mitotic spindle and that it plays a direct, translation-independent role in spindle assembly. Our studies reveal an unexpected function for RNA in spindle morphogenesis. Supplementary data: http://www.cell.com/cgi/content/full/121/2/223/DC1/ _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Additional References: 1. Chang P, Jacobson MK, and Mitchison TJ, "Poly(ADP-ribose) is required for spindle assembly and structure", Nature vol. 432, no. 7017, pp. 645 - 649 (02 December 2004). 2. Karsenti E, "Cytoskeleton: Spindle saga", Nature, vol. 432, no. 7017, pp. 563 - 564 (02 December 2004), 3. Frenster JH, "Nuclear polyanions as de-repressors of synthesis of Ribonucleic Acid", Nature, volume 206, number 4985, pp. 680 - 683 (15 May 1965). _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Links to RNA and Biological Causality: A Brief History of Activator RNA: _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Further Topics in: Euchromatin, active DNA, and RNA ribo-regulators: Links to Euchromatin Activator RNA Reviews: Links to Euchromatin Activator RNA Research: Links to Ultrastructural Probes of DNase I-Sensitive Sites: Links to RNA as a Therapeutic Agent: Links to Hodgkin Lymphoma Immuno-Pathology: Links to Activated T-Lymphocyte Immunotherapy: Links to Medical Systems Biology: Links to Selective Gene Transcription: Links to RNA-Induced Epigenetics: Links to RNA-Induced Embryogenesis: Links to RNA and Biological Causality: Links to Reprogramming and Neoplasia: A Brief History of Activator RNA: "Ultrastructural Probes of Active DNA Sites, and the RNA Activators of DNA". (PowerPoint Presentation). _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ Top of Page - Euchromatin Network - Current Research - Forums - Other Sites - Future Events - _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ For Further Information and Feedback: E-mail: frenster@euchromatin.net Phone: +1 650 367 6483 Fax: +1 650 364 1773 _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________ euchromatin: "the most active portion of the genome within the cell nucleus".