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Updated: Jul 27, 2026
11:32
Analysis of mRNA Nuclear Export Kinetics in Mammalian Cells by Microinjection
Published on: December 4, 2010
Compartmentalization of RNA processing factors within nuclear speckles.
1Department of Molecular Genetics and Microbiology, S.U.N.Y. Stony Brook, Stony Brook, New York, 11794, USA.
Journal of Structural Biology
|May 12, 2000
Summary
Mammalian cell nucleus speckles contain smaller spherical structures called subspeckles. These subspeckles, containing pre-mRNA splicing factors, are dynamic and linked to active transcription sites.
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Pre-mRNA splicing factors in mammalian cell nuclei are organized in a speckled pattern.
- Previous fluorescence microscopy showed homogeneous signals within these nuclear speckles.
Purpose of the Study:
- To re-examine the structural organization of nuclear speckles using advanced microscopy techniques.
- To investigate the substructure of speckles and their relationship with transcription.
Main Methods:
- Immunofluorescence and confocal laser scanning microscopy with serial antibody dilutions.
- Inhibition of RNA polymerase II transcription.
- Fluorescence in situ hybridization (FISH).
Main Results:
- Nuclear speckles revealed numerous spherical subdomains, termed "subspeckles" (0.2-0.5 micrometer).
- Subspeckles formed dynamic strings and loops extending from speckles during active transcription, disappearing upon transcription inhibition.
- Subspeckles colocalized with beta-tropomyosin RNA transcripts.
Conclusions:
- Nuclear speckles possess a complex substructure composed of subspeckles.
- Subspeckle organization is dynamic and linked to active RNA polymerase II transcription.
- Compartmentalization into subspeckles may facilitate the organization and transport of splicing factors to RNA processing sites.
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