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Evidence of an essential role of NHERF1 and NHEF2 in G‐protein coupled receptor regulation of CFTR‐mediated intestinal anion secretion in vivo
Author(s) -
Singh Anurag Kumar,
Riederer Brigitte,
Jonge Hugo R.,
Donowitz Mark,
Weinman Edward J.,
Kocher Olivier,
Hogema Boris M.,
Seidler Ursula
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.796.41
Subject(s) - pdz domain , secretion , microbiology and biotechnology , receptor , chemistry , stimulation , cystic fibrosis transmembrane conductance regulator , forskolin , agonist , medicine , biology , endocrinology , biochemistry , gene
Heterologous expression studies have demonstrated that the PDZ‐proteins NHERF1 and NHERF2 modulate CFTR interaction with other proteins. To study their biological roles in vivo in an epithelium that highly expresses CFTR as well as NHERF1 and 2, we investigated the effect of NHERF1 and 2 ablation on CFTR‐dependent duodenal HCO 3 − secretion. Proximal duodenum of anesthetized mice was perfused in situ, and HCO 3 − secretion was determined by back‐titration. Co‐localization of CFTR, β2‐adrenergic receptor and LPA2 receptors, as well as PDZ proteins in the luminal membrane of crypt duodenocytes were established by Western analysis of isolated brush border membranes, immunohistochemistry and laser micro‐dissection followed by q‐PCR (quantitative‐PCR). NHERF1 ablation strongly reduced basal as well as forskolin (FSK)‐stimulated HCO 3 − secretory rates, and completely prevented β2‐adrenergic stimulation. NHERF2 deletion significantly augmented FSK‐stimulated HCO 3 − secretion, and completely prevented the inhibitory effect of LPA. We conclude that NHERF1 and 2 differentially modulate basal and agonist‐mediated duodenal HCO 3 − secretion in vivo in a CFTR‐dependent fashion. NHERF1 is an obligatory linker for β2‐adrenergic stimulation of CFTR, and strongly augments cAMP‐mediated stimulation. NHERF2 confers inhibitory signals, i.e. as a coupling factor between inhibitory LPA receptor signalling and CFTR.