Guanylin, uroguanylin, and heat-stable euterotoxin activate guanylate cyclase C and/or a pertussis toxin-sensitive G protein in human proximal tubule cells.
Membrane guanylate cyclase C (GC-C) is the receptor for guanylin, uroguanylin, and heat-stable enterotoxin (STa) in the intestine. GC-C-deficient mice show resistance to STa in intestine but saluretic and diuretic effects of uroguanylin and STa are not disturbed. Here we describe the cellular effects of these peptides using immortalized human kidney epithelial (IHKE-1) cells with properties of the proximal tubule, analyzed with the slow-whole-cell patch clamp technique. Uroguanylin (10 or 100 nm) either hyperpolarized or depolarized membrane voltages (V(m)). Guanylin and STa (both 10 or 100 nm), as well as 8-Br-cGMP (100 microm), depolarized V(m). All peptide effects were absent in the presence of 1 mm Ba(2+). Uroguanylin and guanylin changed V(m) pH dependently. Pertussis toxin (1 microg/ml, 24 h) inhibited hyperpolarizations caused by uroguanylin. Depolarizations caused by guanylin and uroguanylin were blocked by the tyrosine kinase inhibitor, genistein (10 microm). All three peptides increased cellular cGMP. mRNA for GC-C was detected in IHKE-1 cells and in isolated human proximal tubules. In IHKE-1 cells GC-C was also detected by immunostaining. These findings suggest that GC-C is probably the receptor for guanylin and STa. For uroguanylin two distinct signaling pathways exist in IHKE-1 cells, one involves GC-C and cGMP as second messenger, the other is cGMP-independent and connected to a pertussis toxin-sensitive G protein.
Sindiće
Aleksandra
A
Medizinische Klinik und Poliklinik D, Experimentelle Nephrologie, Universitätsklinikum Münster, Domagkstr. 3a, D-48149 Münster, Germany.
Başoglu
Candan
C
Cerçi
Ayhan
A
Hirsch
Jochen R
JR
Potthast
Regine
R
Kuhn
Michaela
M
Ghanekar
Yashoda
Y
Visweswariah
Sandhya S
SS
Schlatter
Eberhard
E
D001427:Bacterial Toxins / Q000494:pharmacology*; D001464:Barium / Q000494:pharmacology; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D004768:Enterotoxins / Q000494:pharmacology*; D029968:Escherichia coli Proteins; D005768:Gastrointestinal Hormones; D019833:Genistein / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007687:Kidney Tubules, Proximal / Q000187:drug effects / Q000378:metabolism*; D045265:Natriuretic Peptides; D010455:Peptides / Q000494:pharmacology*; D037342:Pertussis Toxin; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled; D018000:Receptors, Peptide / Q000378:metabolism*; D015398:Signal Transduction; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D005768:Gastrointestinal Hormones; D045265:Natriuretic Peptides; D010455:Peptides; D018000:Receptors, Peptide; D010566:Virulence Factors, Bordetella; C034151:heat stable toxin (E coli); C072685:guanylin; C084362:uroguanylin; D001464:Barium; C016276:8-bromocyclic GMP; D019833:Genistein; D037342:Pertussis Toxin; D006162:Guanylate Cyclase; C000613655:Gucy2c protein, mouse; D000074261:Receptors, Enterotoxin; D050705:Receptors, Guanylate Cyclase-Coupled; D006152:Cyclic GMP