We have recently shown that discrete foci are present in the nuclei of mammalian cells in which each of the U1, U2, U4/U6, and U5 snRNPs involved in pre-mRNA splicing, and the non-snRNP-splicing factor U2AF, are concentrated (Carmo-Fonseca, M., D. Tollervey, R. Pepperkok, S. Barabino, A. Merdes, C. Brunner, P. D. Zamore, M. R. Green, E. Hurt, and A. I. Lamond. 1991. EMBO (Eur. Mol. Biol. Organ.) J. 10:195-206; Carmo-Fonseca, M., R. Pepperkok, B. S. Sproat, W. Ansorge, M. S. Swanson, and A. I. Lamond. 1991 EMBO (Eur. Mol. Biol. Organ.) J. 10:1863-1873). Here, we identify these snRNP-rich organelles as coiled bodies. snRNPs no longer concentrate in coiled bodies after cells are treated with the transcription inhibitors alpha-amanitin or actinomycin D. snRNP association with coiled bodies is also disrupted by heat shock. This indicates that the association of snRNPs with coiled bodies may be connected with the metabolism of nascent transcripts. A novel labeling method is described which shows both the RNA and protein components of individual snRNPs colocalizing in situ. Using this procedure all spliceosomal snRNPs are seen distributed in a nonhomogeneous pattern throughout the nucleoplasm, excluding nucleoli. They are most concentrated in coiled bodies, but in addition are present in "speckled" structures which are distinct from coiled bodies and which contain the non-snRNP splicing factor SC-35. U1 snRNP shows a more widespread nucleoplasmic staining, outside of coiled bodies and "speckled" structures, relative to the other snRNPs. The association of snRNPs with "speckles" is disrupted by heat shock but enhanced when cells are treated with alpha-amanitin.
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1 April 1992
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April 01 1992
Transcription-dependent colocalization of the U1, U2, U4/U6, and U5 snRNPs in coiled bodies
In Special Collection:
JCB65: RNA
M Carmo-Fonseca,
M Carmo-Fonseca
European Molecular Biology Laboratory, Heidelberg, Germany.
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R Pepperkok,
R Pepperkok
European Molecular Biology Laboratory, Heidelberg, Germany.
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MT Carvalho,
MT Carvalho
European Molecular Biology Laboratory, Heidelberg, Germany.
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AI Lamond
AI Lamond
European Molecular Biology Laboratory, Heidelberg, Germany.
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M Carmo-Fonseca
European Molecular Biology Laboratory, Heidelberg, Germany.
R Pepperkok
European Molecular Biology Laboratory, Heidelberg, Germany.
MT Carvalho
European Molecular Biology Laboratory, Heidelberg, Germany.
AI Lamond
European Molecular Biology Laboratory, Heidelberg, Germany.
Online ISSN: 1540-8140
Print ISSN: 0021-9525
J Cell Biol (1992) 117 (1): 1–14.
Citation
M Carmo-Fonseca, R Pepperkok, MT Carvalho, AI Lamond; Transcription-dependent colocalization of the U1, U2, U4/U6, and U5 snRNPs in coiled bodies. J Cell Biol 1 April 1992; 117 (1): 1–14. doi: https://doi.org/10.1083/jcb.117.1.1
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