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Corticotropin-releasing factor increases protein kinase C activity by elevating membrane-bound alpha and beta
J G Kiang1, X Wang, D E McClain
1Department of Clinical Physiology, Walter Reed Army Institute of Research, Washington, DC 20307-5100.
The Chinese Journal of Physiology
|January 1, 1994
Summary
Corticotropin-releasing factor (CRF) reduces vascular leakage. CRF increases intracellular calcium, which mediates protein kinase C (PKC) activity and isoform translocation in human A-431 cells.
Area of Science:
- Cell Biology
- Biochemistry
- Physiology
Background:
- Corticotropin-releasing factor (CRF) attenuates vascular leakage across various tissues.
- Previous studies show CRF elevates cytosolic free calcium ([Ca2+]i), cAMP, and inositol trisphosphates in A-431 cells.
Purpose of the Study:
- Identify protein kinase C (PKC) isoforms in A-431 cells.
- Investigate CRF's effect on PKC activity and isoform translocation.
- Determine the role of intracellular calcium in CRF-mediated PKC activation.
Main Methods:
- Protein kinase C isoform identification in cytosolic and membrane fractions of A-431 cells.
- Assessment of CRF's impact on PKC activity and isoform translocation.
- Evaluation of calcium's role using BAPTA-am, an intracellular calcium chelator.
Main Results:
- PKC alpha, beta, gamma, delta, and zeta isoforms were found in both cytosolic and membrane fractions.
- CRF exposure increased PKC activity and induced translocation of PKC alpha and beta isoforms from cytosol to membrane.
- Inhibition of intracellular calcium increase with BAPTA-am abolished CRF-induced PKC activity and translocation.
Conclusions:
- CRF activates protein kinase C signaling pathway in A-431 cells.
- CRF-induced increase in intracellular calcium is essential for activating PKC and mediating isoform translocation.
- This calcium-dependent PKC activation may contribute to CRF's vascular protective effects.