Activation of the cystic fibrosis transmembrane conductance regulator by cGMP in the human colonic cancer cell line, Caco-2.
Year: 1994
Type: article
Abstract: Intestinal chloride (Cl-) secretion can be induced by the heat-stable enterotoxin (STa) from Escherichia coli via generation of cGMP. We investigated the regulatory pathway responsible for cGMP-mediated Cl- secretion in the human colonic carcinoma cell line Caco-2 using whole-cell voltage clamp techniques. Cyclic GMP or cAMP induced a 5-fold increase in Cl- conductance (gCl) in the presence of intracellular ATP and 3-isobutyl-1-methylxanthine. Current activation by cGMP persisted in the presence of the type I cGMP-dependent protein kinase (PKG) inhibitor, KT5823, but was inhibited by the specific peptide inhibitor of the cAMP-dependent protein kinase A (PKA), PKI5-24. The stimulatory effects of cGMP and cAMP on gCl were not additive. The cystic fibrosis transmembrane conductance regulator (CFTR) is a Cl- channel that is regulated by intracellular ATP and by cAMP-dependent phosphorylation. In order to determine whether CFTR was involved in the cGMP-dependent increase in gCl, we tested the effect of intracellularly injected anti-CFTR505-511 antibodies previously shown to inhibit CFTR function. Antibodies introduced into individual cells via the patch pipette completely inhibited cGMP-dependent current activation. Cyclic GMP also failed to activate gCl in cystic fibrosis cells. Taken together, these studies demonstrate that activation of the CFTR via PKA-dependent phosphorylation accounts for the cGMP-mediated increase in Cl- secretion in Caco-2 cells.
Source: Journal of Biological Chemistry
Institution: University of Chicago
Language: English
Subfield: Pulmonary and Respiratory Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W1588537646