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Membrane trafficking of NBCe1 but not NBCn1 in rat parotid acinar ParC5 cells
Author(s) -
Grichtchenko irina I,
Reyland Mary,
Perry Clint J
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.800.1
Subject(s) - internalization , microbiology and biotechnology , endocytosis , endosome , chemistry , protein kinase c , exocytosis , biology , intracellular , secretion , endocrinology , medicine , cell , biochemistry , kinase
We examined membrane trafficking of "renal" NBCe1‐A and "pancreas" NBCe1‐B, and NBCn1 in ParC5 cells by biotinylation and confocal microscopy using fluorescent tags and endosomal markers. We localized NBCe1 and NBCn1 at the basolateral membrane (BLM) in polarized cells. We blocked constitutive recycling with monensin and detected that both NBCe1‐A/B accumulated in endosomes with a parallel loss from the BLM. We observed that both NBCe1‐A/B undergo a massive carbachol‐stimulated redistribution from the BLM into early and recycling endosomes. We inhibited internalization of NBCe1‐A by transfecting cells with the kinase‐dead (Lys376Arg) PKCd mutant, and inhibited internalization of both NBCe1‐A/B by total PKC inhibitor GF109203X, PKCaβγ inhibitor GÖ6976, and PKCδ inhibitor rottlerin. Our data suggest that "renal" and "pancreas" variants of NBCe1 undergo constitutive and stimulated PKC‐regulated endocytosis in acinar cells. In contrast, NBCn1 remained stably present at the BLM after treatment with monensin, carbachol, or PMA. We speculate that endocytosis of NBCe1, which coincides with the sustained phase of stimulated fluid secretion, could be a part of cell adjustment to a steady state characteristic of a continuous secretory response. At the same time, stable NBCn1 could constantly participate in maintaining acid‐base homeostasis in stimulated saliva‐secreted parotid acinar cells.