A role for Cajal bodies in the final steps of U2 snRNP biogenesis

Article Article scientifique Article A role for Cajal bodies in the final steps of U2 snRNP biogenesis eng 2004 author Nesic Dobrila 0000-0003-1609-9255 30119 author Tanackovic Goranka 520443 author Kraemer Angela 22808 4423-4433 10.1242/jcs.01308 15316075 0021-9533 http://jcs.biologists.org/content/117/19/4423.abstract The biogenesis of Sm-type small nuclear ribonucleoproteins (snRNPs) involves the export of newly transcribed small nuclear RNAs (snRNAs) to the cytoplasm, assembly with seven common proteins and modification at the 5' and 3' termini. Binding of snRNP-specific proteins and snRNA modification complete the maturation process. This is thought to occur after reimport of the core snRNPs into the nucleus. The heterotrimeric splicing factor SF3a converts a pre-mature 15S U2 snRNP into the functional 17S particle. To analyze cellular aspects of this process, we studied domains in SF3a60 and SF3a66 that are required for their localization to nuclear speckles. Regions in SF3a60 and SF3a66 that mediate the binding to SF3a120 are necessary for nuclear import of the proteins, suggesting that the SF3a heterotrimer forms in the cytoplasm. SF3a60 and SF3a66 deleted for zinc finger domains required for the incorporation of SF3a into the U2 snRNP are nuclear, indicating that the 17S U2 snRNP is assembled in the nucleus. However, these proteins show an aberrant nuclear distribution. Endogenous SF3a subunits colocalize with U2 snRNP in nuclear speckles, but cannot be detected in Cajal bodies, unlike core U2 snRNP components. By contrast, SF3a60 and SF3a66 lacking the zinc finger domains accumulate in Cajal bodies and are diffusely distributed in the cytoplasm, suggesting a function for Cajal bodies in the final maturation of the U2 snRNP. Active Transport, Cell Nucleus/physiology Cell Nucleus/metabolism Coiled Bodies/metabolism Cytoplasm/metabolism Hela Cells Humans Protein Subunits/metabolism RNA, Small Nuclear/metabolism Ribonucleoprotein, U2 Small Nuclear/metabolism Ribonucleoproteins, Small Nuclear/metabolism Zinc Fingers/physiology Dewey 570 46 Département de biologie cellulaire 165 false Journal of cell science 117 Pt 19 045e2d8c-b1a9-4f48-ba0f-53d3fdaec379 Article (Published version) Public 2004_Nesic_JCS.pdf 544374 application/pdf openAccess Faculté des sciences / Section de biologie / Département de biologie cellulaire

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A role for Cajal bodies in the final steps of U2 snRNP biogenesis	Journal of cell science			2004	655	645

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Tanackovic, Goranka