The Cajal body a meeting place for spliceosomal s

Authors: David Staněk Karla M Neugebauer

Publish Date: 2006/03/31

Volume: 115, Issue: 5, Pages: 343-354

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Abstract

Spliceosomal small nuclear ribonucleoprotein particles snRNPs are essential premRNA splicing factors that consist of small nuclear RNAs snRNAs complexed with specific sets of proteins A considerable body of evidence has established that snRNP assembly is accomplished after snRNA synthesis in the nucleus through a series of steps involving cytoplasmic and nuclear phases Recent work indicates that snRNPs transiently localize to the Cajal body CB a nonmembranebound inclusion present in the nuclei of most cells for the final steps in snRNP maturation including snRNA base modification U4/U6 snRNA annealing and snRNAprotein assembly Here we review these findings that suggest a crucial role for CBs in the spliceosome cycle in which production of new snRNPs—and perhaps regenerated snRNPs after splicing—is promoted by the concentration of substrates in this previously mysterious subnuclear organelle These insights allow us to speculate on the role of nuclear bodies in regulating the dynamics of RNP assembly to maintain a functional pool of factors available for key steps in gene expressionWork in our laboratories is supported by the Max Planck Society a grant to KMN from the Deutsche Forschung Gemeinschaft NE909/11 and grants to DS from Granting Agency of the Czech Republic 301/05/0601 and the Czech Ministry of Education 1K05009 MSM0021620806 AV0Z50110509 and LC535 We thank Christine Panagiotidis for help with graphics and Mirko Klingauf Magda Strzelecka and Arnold Kiss for helpful discussions and comments on the manuscript

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