Dynamic interactions between splicing snRNPs, coiled bodies and nucleoli revealed using snRNP protein fusions to the green fluorescent protein

Judith Sleeman, Carol E. Lyon, Melpomeni Platani, Jan Peter Kreivi, Angus I. Lamond

    Research output: Contribution to journalArticlepeer-review

    97 Citations (Scopus)

    Abstract

    The U1, U2, U4/U6, and U5 small nuclear ribonucleoproteins (snRNPs) are subunits of splicing complexes that remove introns from mRNA precursors. snRNPs show a complex, transcription-dependent localization pattern in the nucleoplasm of mammalian cells that results from their association with several distinct subnuclear structures, including interchromatin granule clusters, perichromatin fibrils, and coiled bodies. Here we report the analysis of snRNP localization and interaction with the coiled body in live human cells using fusions of snRNP proteins and p80 coilin to the Green Fluorescent Protein (GFP). Despite the large size of the GFP tag, GFP fusions to both the core snRNP SInE and U1 specific U1A proteins assemble into snRNP particles and give an identical nuclear localization pattern to their endogenous counterparts. GFP-coilin localizes specifically to coiled bodies in a transcription-dependent fashion and provides an accurate marker for coiled bodies in a variety of human cell lines. Treatment of cells with the selective ser/thrprotein phosphatase inhibitor, okadaic acid, causes both GFP-snRNP and GFP-coilin proteins to accumulate within nucleoli, but does not result in nucleolar accumulation of the GFP-fused non-snRNP protein splicing factor ASF/SF2. In all four human cell lines tested, expression of a GFP- fused p80 coilin mutant with a single serine to aspartate substitution also caused nucleolar accumulation of splicing snRNPs and coilin, but not ASF/SF2, in structures resembling coiled bodies when viewed by electron microscopy. This work establishes an experimental system for analyzing snRNP trafficking in living cells and provides evidence that a reversible protein phosphorylation mechanism is involved in regulating interaction of snRNPs and coiled bodies with the nucleolus.

    Original languageEnglish
    Pages (from-to)290-304
    Number of pages15
    JournalExperimental Cell Research
    Volume243
    Issue number2
    DOIs
    Publication statusPublished - 15 Sept 1998

    ASJC Scopus subject areas

    • Cell Biology

    Fingerprint

    Dive into the research topics of 'Dynamic interactions between splicing snRNPs, coiled bodies and nucleoli revealed using snRNP protein fusions to the green fluorescent protein'. Together they form a unique fingerprint.

    Cite this