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Structural and functional heterogeneity of nuclear bodies
D B Bloch1, J D Chiche, D Orth
1Department of Medicine, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts. bloch@helix.mgh.harvard
Molecular and Cellular Biology
|May 18, 1999
Summary
The Sp140 protein associates with nuclear bodies containing PML and Sp100, particularly after gamma interferon (IFN-gamma) treatment. Sp140 may play a role in activating gene transcription, suggesting nuclear bodies have diverse functions.
Area of Science:
- Cellular Biology
- Molecular Biology
- Gene Regulation
Background:
- Nuclear bodies are implicated in acute promyelocytic leukemia and viral infections.
- Nuclear bodies are targets of autoantibodies in primary biliary cirrhosis.
- The precise function of nuclear bodies in normal cellular biology remains unknown, but they may regulate gene transcription.
Purpose of the Study:
- To investigate the cellular localization of Sp140 in relation to nuclear body components PML and Sp100.
- To examine the potential role of Sp140 in the regulation of gene transcription.
Main Methods:
- Adenovirus-mediated gene transfer to express Sp140 in human cells.
- Immunofluorescence microscopy to observe Sp140 colocalization with PML and Sp100.
- Reporter gene assays (GAL4-Sp140 fusion protein and CAT reporter gene) to assess transcriptional activity.
Main Results:
- Sp140 colocalized with PML and Sp100 in resting cells and associated with PML during mitosis.
- IFN-gamma treatment increased the number of PML-Sp100 nuclear bodies, with Sp140 associating with a subset.
- GAL4-Sp140 fusion protein enhanced reporter gene expression, indicating transcriptional activation, while GAL4-Sp100 inhibited it.
Conclusions:
- Sp140 associates with a subset of PML-Sp100 nuclear bodies in IFN-gamma-treated cells.
- Sp140 demonstrates potential to activate gene transcription.
- These findings suggest heterogeneity in nuclear body composition and function.