The PDZ-domain binding protein PDZK1/CAP70 is involved in the regulation of murine intestinal NHE3 and CFTR function

Background: The molecular mechanisms of secretory diarrhea are stimulation of intestinal anion secretion – predominantly via CFTR Cl- channel activation–and an inhibition of salt absorption – predominantly via Na+/H+ exchanger isoform NHE3 inhibition. Recent investigations revealed a regulatory function of each of three PDZ-binding proteins, namely NHERF1, 2 and PDZK1, in transport rate regulation and trafficking of CFTR and NHE3 in heterologous expression systems. Their functions in native intestine, which expresses all three adapter proteins, are unknown. Methods: We bred PDZK1 -/- and +/+ mice, and measured b…