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HCF-dependent nuclear import of VP16
S La Boissière1, T Hughes, P O'Hare
1Marie Curie Research Institute, The Chart, Oxted, Surrey RH8 OTL, UK.
The EMBO Journal
|January 16, 1999
Summary
Herpes simplex virus transactivator VP16 requires cellular protein HCF for nuclear import. HCF acts as a nuclear import factor, facilitating VP16
Area of Science:
- Molecular Biology
- Cell Biology
- Virology
Background:
- VP16 (Herpes Simplex Virus transcriptional activator) forms a complex (TRF.C) with cellular proteins Oct-1 and HCF for gene transactivation.
- HCF binds VP16, facilitating complex formation with Oct-1 at target DNA sites.
Purpose of the Study:
- To investigate the role of HCF in the intracellular localization of VP16.
- To determine if HCF influences VP16's entry into the cell nucleus.
Main Methods:
- Co-expression experiments of VP16 and HCF (wild-type and mutants) in cells.
- Identification and functional testing of a Nuclear Localization Signal (NLS) in HCF.
- Utilizing Green Fluorescent Protein (GFP) as a reporter for NLS activity.
Main Results:
- VP16, lacking a canonical NLS, is primarily cytoplasmic.
- Co-expression with HCF promotes VP16 nuclear accumulation.
- A C-terminal motif in HCF functions as an NLS, mediating VP16 nuclear import.
- HCF mutants lacking the NLS or VP16 mutants lacking HCF-binding ability fail to achieve VP16 nuclear enrichment.
Conclusions:
- HCF functions as a nuclear import factor for VP16, in addition to its role in TRF.C complex stabilization.
- HCF's NLS is critical for directing VP16 into the nucleus.