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The Rho exchange factor Net1 is regulated by nuclear sequestration
1Medical Research Council Laboratory for Molecular Cell Biology and Cancer Research Campaign Oncogene and Signal Transduction Group, University College London, Gower Street, London WC1E 6BT, United Kingdom.
The Journal of Biological Chemistry
|February 13, 2002
Summary
Net1 protein regulates Rho GTPase activity. Its N-terminus controls nuclear import, while the PH domain mediates nuclear export, revealing subcellular localization as key to Net1 activation.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Net1 is a guanine nucleotide exchange factor (GEF) specific for Rho GTPase.
- Oncogenic activation of Net1 involves truncation of its N-terminal negative regulatory domain.
Purpose of the Study:
- Investigate the mechanism of Net1 regulation by its N-terminus.
- Determine the role of subcellular localization in Net1 activity.
Main Methods:
- Subcellular localization studies using microscopy.
- Analysis of nuclear localization signals (NLS) and nuclear export signals (NES).
- Mutagenesis of the Net1 PH domain.
Main Results:
- Net1 localizes to the nucleus, while oncogenic Net1 is found in the cytoplasm.
- Nuclear import is mediated by NLS in the N-terminus.
- The PH domain functions as an NES, independent of GEF activity.
- Forced cytoplasmic localization activates Rho.
Conclusions:
- Net1 shuttles between the nucleus and cytoplasm.
- Subcellular localization dynamically regulates Net1's GEF activity.
- The PH domain has dual functions in nuclear export and GEF regulation.
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