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.

Abstract

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 IP3-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 Gö6976 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 Gö6976 suggested the involvement of PKC(alpha) in the regulation of guanylate cyclase activity.

• Authors: Dyuti Datta Gupta, Subhrajit Saha, Manoj K Chakrabarti
• Journal: Toxicology and applied pharmacology (Toxicol Appl Pharmacol) Vol. 206 Issue 1 Pg. 9-16 (Aug 01 2005) ISSN: 0041-008X [Print] United States
• PMID: 15963340 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Bacterial Toxins
• Carbazoles
• Enterotoxins
• Enzyme Inhibitors
• Escherichia coli Proteins
• Indoles
• Isoenzymes
• heat stable toxin (E coli)
• Go 6976
• Protein Kinase C
• Guanylate Cyclase
• Calcium

Topics

• Bacterial Toxins (pharmacology)
• Calcium (physiology)
• Carbazoles (pharmacology)
• Cell Line, Tumor
• Cell Membrane (drug effects, enzymology)
• Enterotoxins (pharmacology)
• Enzyme Activation (drug effects)
• Enzyme Inhibitors (pharmacology)
• Escherichia coli Proteins
• Guanylate Cyclase (metabolism)
• Humans
• Indoles (pharmacology)
• Isoenzymes (metabolism)
• Protein Kinase C (antagonists & inhibitors, metabolism)