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Binding of 14-3-3 proteins and nuclear export control the intracellular localization of the mitotic inducer Cdc25
1Division of Biology 216-76, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125, USA.
Abstract:
Binding of 14-3-3 proteins near the nuclear localization sequence of Xenopus Cdc25 suppresses its ability to induce entry into mitosis. We have examined the intracellular localization of green fluorescent protein (GFP)-tagged wild-type Cdc25 or a mutant (S287A) that cannot bind 14-3-3 proteins. Upon coexpression with Myc-14-3-3epsilon, GFP-Cdc25-WT was predominantly cytoplasmic, whereas GFP-Cdc25-S287A was exclusively nuclear. Leptomycin B, an inhibitor of nuclear export, elicited a prompt redistribution of GFP-Cdc25-WT to the nucleus. Mutagenesis experiments demonstrated that Cdc25 contains multiple nuclear export sequences. These studies indicate that the binding of 14-3-3 proteins and nuclear export regulate the intracellular localization of Cdc25.
Insights
14-3-3 proteins binding to Xenopus Cdc25 regulates its cell cycle function. This study shows 14-3-3 binding and nuclear export control Cdc25
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- 14-3-3 proteins are key regulators of cell signaling.
- Cdc25 is a crucial regulator of cell cycle progression.
- The subcellular localization of Cdc25 impacts its function.
Purpose of the Study:
- To investigate how 14-3-3 proteins and nuclear export influence Cdc25 localization.
- To determine the role of Cdc25's nuclear localization in mitosis entry.
Main Methods:
- Utilized green fluorescent protein (GFP)-tagged wild-type and mutant Cdc25.
- Coexpressed Cdc25 constructs with Myc-14-3-3epsilon.
- Employed Leptomycin B, a nuclear export inhibitor.
- Performed mutagenesis experiments to identify nuclear export sequences.
Main Results:
- GFP-Cdc25-WT localized predominantly in the cytoplasm upon coexpression with Myc-14-3-3epsilon.
- GFP-Cdc25-S287A, unable to bind 14-3-3, was exclusively nuclear.
- Leptomycin B treatment caused GFP-Cdc25-WT to redistribute to the nucleus.
- Mutagenesis revealed multiple nuclear export sequences within Cdc25.
Conclusions:
- 14-3-3 protein binding suppresses Cdc25's ability to induce mitosis entry.
- Nuclear export and 14-3-3 binding are critical regulators of Cdc25 intracellular localization.
- Cdc25's localization is a key determinant of its cell cycle control function.