Involvement of protein kinase C in the mechanism of action of Escherichia coli heat-stable enterotoxin (STa) in a human colonic carcinoma cell line, COLO-205
- Division of Pathophysiology, National Institute of Cholera and Enteric Diseases, P-33, C. I. T. Road, Scheme-XM, Beliaghata, Kolkata-700 010 (India)
The present study was undertaken to determine the involvement of calcium-protein kinase C pathway in the mechanism of action of Escherichia coli heat stable enterotoxin (STa) apart from STa-induced activation of guanylate cyclase in human colonic carcinoma cell line COLO-205, which was used as a model cultured cell line to study the mechanism of action of E. coli STa. In response to E. coli STa, protein kinase C (PKC) activity was increased in a time-dependent manner with its physical translocation from cytosol to membrane. Inhibition of the PKC activity in membrane fraction and inhibition of its physical translocation in response to IP{sub 3}-mediated calcium release inhibitor dantrolene suggested the involvement of intracellular store depletion in the regulation of PKC activity. Among different PKC isoforms, predominant involvement of calcium-dependent protein kinase C (PKC{alpha}) was specified using isotype-specific pseudosubstrate, which showed pronounce enzyme activity. Inhibition of enzyme activity by PKC{alpha}-specific inhibitor Goe6976 and immunoblott study employing isotype-specific antibody further demonstrated the involvement of calcium-dependent isoform of PKC in the mechanism of action of E. coli STa. Moreover, inhibition of guanylate cyclase activity by PKC{alpha}-specific inhibitor Goe6976 suggested the involvement of PKC{alpha} in the regulation of guanylate cyclase activity.
- OSTI ID:
- 20721830
- Journal Information:
- Toxicology and Applied Pharmacology, Vol. 206, Issue 1; Other Information: DOI: 10.1016/j.taap.2004.11.001; PII: S0041-008X(04)00499-5; Copyright (c) 2004 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0041-008X
- Country of Publication:
- United States
- Language:
- English
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