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Cell cycle-dependent subcellular localization of exchange factor directly activated by cAMP
Jingbo Qiao1, Fang C Mei, Vsevolod L Popov
1Department of Pharmacology and Toxicology, Sealy Center for Structural Biology, The University of Texas Medical Branch, Galveston, Texas 77555, USA.
The Journal of Biological Chemistry
|May 10, 2002
Summary
Epac protein localization changes during cell division, moving from the nuclear membrane to the mitotic spindle and contractile ring. This dynamic Epac/Rap1 pathway suggests a key role in regulating mitosis.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Epac is a novel protein mediating cyclic AMP (cAMP) signaling by activating the Rap1 GTPase.
- The Epac/Rap1 pathway is a cAMP-signaling cascade independent of protein kinase A (PKA).
Purpose of the Study:
- To investigate the intracellular localization of Epac throughout the cell division cycle.
- To identify structural elements governing Epac's subcellular localization.
Main Methods:
- Fluorescence microscopy was used to observe Epac localization in COS-7 cells.
- Deletion mutagenesis was employed to map Epac's functional domains.
Main Results:
- Epac localizes to the nuclear membrane and mitochondria during interphase.
- The DEP domain mediates membrane association, and the N-terminus contains a mitochondrial-targeting sequence.
- Epac dynamically relocates to the mitotic spindle and centrosomes during metaphase and the contractile ring at the end of the cell cycle.
- Overexpression of Epac resulted in multinucleated cells.
Conclusions:
- Epac exhibits cell cycle-dependent subcellular localization.
- Epac's dynamic localization suggests a significant role in regulating mitosis and cytokinesis.