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Bicarbonate-responsive "soluble" adenylyl cyclase defines a nuclear cAMP microdomain
Jonathan H Zippin1, Jeanne Farrell, David Huron
1Department of Pharmacology, Joan and Sanford I. Weill Medical College and Graduate School of Medical Sciences of Cornell University, 1300 York Ave., New York, NY 10021, USA.
The Journal of Cell Biology
|February 11, 2004
Summary
A novel nuclear cyclic adenosine monophosphate (cAMP) pathway was discovered. This pathway activates the cAMP response element binding protein (CREB) through nuclear protein kinase A, revealing intracellular cAMP signaling microdomains.
Area of Science:
- Cellular Biology
- Molecular Biology
- Biochemistry
Background:
- Cyclic adenosine monophosphate (cAMP) is a crucial second messenger involved in various cellular processes.
- The localization and function of adenylyl cyclase, particularly in the nucleus, remain areas of active investigation.
- Activation of the cAMP response element binding protein (CREB) is critical for gene expression and neuronal plasticity.
Purpose of the Study:
- To investigate the subcellular localization and function of bicarbonate-responsive soluble adenylyl cyclase.
- To elucidate the role of nuclear adenylyl cyclase in cAMP signaling.
- To determine the impact of nuclear cAMP signaling on CREB phosphorylation.
Main Methods:
- Cellular fractionation to isolate nuclear components.
- Biochemical assays to measure adenylyl cyclase activity.
- Western blotting to detect phosphorylated CREB.
Main Results:
- Bicarbonate-responsive soluble adenylyl cyclase was found to be present in the mammalian cell nucleus.
- Nuclear adenylyl cyclase activity stimulated nuclear protein kinase A.
- This led to the phosphorylation of the cAMP response element binding protein (CREB) within the nucleus.
Conclusions:
- A complete and functional cAMP signaling pathway exists within the mammalian cell nucleus.
- This nuclear pathway activates CREB, suggesting localized cAMP signaling in intracellular microdomains.
- Identifies an alternative pathway for CREB activation distinct from previously known cytoplasmic pathways.