U4 snRNA nucleolar localization requires the NHPX/15.5-kD protein binding site but not Sm protein or U6 snRNA association
Open Access
- 25 August 2003
- journal article
- Published by Rockefeller University Press in The Journal of cell biology
- Vol. 162 (5), 821-832
- https://doi.org/10.1083/jcb.200301071
Abstract
All small nuclear RNAs (snRNAs) of the [U4/U6.U5] tri-snRNP localize transiently to nucleoli, as visualized by microscopy after injection of fluorescein-labeled transcripts into Xenopus laevis oocyte nuclei. Here, we demonstrate that these RNAs traffic to nucleoli independently of one another, because U4 snRNA deleted in the U6 base-pairing region still localizes to nucleoli. Furthermore, depletion of endogenous U6 snRNA does not affect nucleolar localization of injected U4 or U5. The wild-type U4 transcripts used here are functional: they exhibit normal nucleocytoplasmic traffic, associate with Sm proteins, form the [U4/U6] di-snRNP, and localize to nucleoli and Cajal bodies. The nucleolar localization element (NoLE) of U4 snRNA was mapped by mutagenesis. Neither the 5′-cap nor the 3′-region of U4, which includes the Sm protein binding site, are essential for nucleolar localization. The only region in U4 snRNA required for nucleolar localization is the 5′-proximal stem loop, which contains the binding site for the NHPX/15.5-kD protein. Even mutation of just five nucleotides, essential for binding this protein, impaired U4 nucleolar localization. Intriguingly, the NHPX/15.5-kD protein also binds the nucleolar localization element of box C/D small nucleolar RNAs, suggesting that this protein might mediate nucleolar localization of several small RNAs.Keywords
This publication has 49 references indexed in Scilit:
- The nucleolus: a site of ribonucleoprotein maturationCurrent Opinion in Cell Biology, 2003
- Targeting of U4/U6 small nuclear RNP assembly factor SART3/p110 to Cajal bodiesThe Journal of cell biology, 2003
- All Small Nuclear RNAs (snRNAs) of the [U4/U6.U5] Tri-snRNP Localize to Nucleoli; Identification of the Nucleolar Localization Element of U6 snRNAMolecular Biology of the Cell, 2002
- p110, a novel human U6 snRNP protein and U4/U6 snRNP recycling factorThe EMBO Journal, 2002
- In vivo analysis of NHPX reveals a novel nucleolar localization pathway involving a transient accumulation in splicing specklesThe Journal of cell biology, 2002
- Hypermethylation of the Cap Structure of Both Yeast snRNAs and snoRNAs Requires a Conserved Methyltransferase that Is Localized to the NucleolusMolecular Cell, 2002
- Nuclear transport of U1 snRNP in somatic cells: differences in signal requirement compared with Xenopus laevis oocytes.The Journal of cell biology, 1994
- Transcription-dependent colocalization of the U1, U2, U4/U6, and U5 snRNPs in coiled bodiesThe Journal of cell biology, 1992
- Immunoaffinity purification of a [U4/U6.U5] tri-snRNP from human cells.Genes & Development, 1991
- Diversity in the signals required for nuclear accumulation of U snRNPs and variety in the pathways of nuclear transport.The Journal of cell biology, 1991