Activation of calcium channels by cAMP in STC-1 cells is dependent upon Ca2+ calmodulin-dependent protein kinase II.
Activation of L-type calcium channels in the neuroendocrine, cholecytstokinin-secreting cell line, STC-1, is vital for secretion of CCK. In the present study, the regulation of L-type Ca2+ channels by cAMP and Ca2+ calmodulin dependent protein kinase II (CaM-KII) in STC-1 cells was investigated. Exposure to 3-isobutyl-1-methylxanthine (IBMX) increased intracellular cAMP levels, whole cell Ca2+ currents and activated Ca2+ channels in cell-attached membrane patches. Furthermore, in Fura-2AM loaded cells, cytosolic Ca2+ levels increased upon exposure to IBMX. By contrast, pretreatment of cells with the CaM-KII inhibitor KN-62, prevented IBMX activation of Ca2+ channels in cell-attached patches or increases in cytosolic Ca2+ levels. Inclusion of the synthetic peptide fragment 290-309 of CaM-KII, a CaM-KII antagonist, in the pipette solution, blocked the activation of whole cell Ca2+ currents upon addition of IBMX. These results indicate a unique mechanism of L-type Ca2+ channel activation involving two phosphorylation events.
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Related Subject Headings
- Patch-Clamp Techniques
- Membrane Potentials
- Cyclic AMP
- Cell Line
- Calcium-Calmodulin-Dependent Protein Kinases
- Calcium-Calmodulin-Dependent Protein Kinase Type 2
- Calcium Channels, L-Type
- Calcium Channels
- Calcium
- Biochemistry & Molecular Biology
Citation
Published In
DOI
ISSN
Publication Date
Volume
Issue
Start / End Page
Location
Related Subject Headings
- Patch-Clamp Techniques
- Membrane Potentials
- Cyclic AMP
- Cell Line
- Calcium-Calmodulin-Dependent Protein Kinases
- Calcium-Calmodulin-Dependent Protein Kinase Type 2
- Calcium Channels, L-Type
- Calcium Channels
- Calcium
- Biochemistry & Molecular Biology