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Updated: Jul 4, 2026
07:35
Analysis of Spliceosomal snRNA Localization in Human Hela Cells Using Microinjection
Published on: August 6, 2019
Minor spliceosome components are predominantly localized in the nucleus
Heli K J Pessa1, Cindy L Will, Xiaojuan Meng
1Institute of Biotechnology, PL 56 (Viikinkaari 9), and Institute of Biomedicine, Biomedicum Helsinki, PL 63 (Haartmaninkatu 8), University of Helsinki, FIN-00014, Helsinki, Finland.
Summary
This study investigated the cellular location of spliceosome components. Contrary to recent reports, both major and minor spliceosomes, including U11 and U12 small nuclear RNAs, are found predominantly in the nucleus.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Recent reports suggested a differential subcellular distribution of major (U2-dependent) and minor (U12-dependent) spliceosome components.
- These reports proposed that the minor spliceosome might function in the cytoplasm.
Purpose of the Study:
- To investigate the subcellular localization of small nuclear RNA (snRNA) components of both major and minor spliceosomes.
- To clarify the cellular distribution of spliceosome machinery.
Main Methods:
- In situ hybridization was performed on mouse tissues and human cells to detect snRNA localization.
- Nuclear and cytoplasmic fractions from human cells were analyzed for spliceosomal snRNAs and proteins.
Main Results:
- All spliceosomal snRNAs, including U11 and U12, were found to be almost exclusively localized within the nucleus in both mouse tissues and human cells.
- U11 and U12 snRNAs were observed to colocalize with U4 and U2 snRNAs, respectively, in human cells.
- Analysis of cellular fractions showed identical subcellular distributions for components of both U12- and U2-dependent spliceosomes.
Conclusions:
- The findings establish that components of the U12-dependent spliceosome are predominantly nuclear, similar to the major spliceosome.
- This contradicts previous suggestions of cytoplasmic localization for minor spliceosome components.
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