Rab11a redistributes to apical secretory canaliculus during stimulation of gastric parietal cells

• Published in: American Journal of Physiology: Cell Physiology 1998-07, Vol.275 (1), p.C163-C170
• Main Authors: Calhoun, Benjamin C, Lapierre, Lynne A, Chew, Catherine S, Goldenring, James R
• Format: Article
• Language: English
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.1998.275.1.c163

Institute for Molecular Medicine and Genetics, Departments of Medicine, Surgery, and Cellular Biology and Anatomy, Medical College of Georgia, and Augusta Veterans Affairs Medical Center, Augusta, Georgia 30912 Previous investigations in several systems have demonstrated that Rab3 family members redistribute to soluble fractions on fusion of secretory granules with target plasma membranes. Rab proteins are then recycled back onto mature secretory vesicles after reinternalization of the membrane. Although this cycle is well established for Rab3, far less is known about redistribution of other Rab proteins during vesicle fusion and recycling. In the gastric parietal cell, Rab11a is associated with H-K-ATPase-containing tubulovesicles, which fuse with the apical plasma membrane (secretory canaliculus) in response to agonists such as histamine. We have analyzed distribution of Rab11a and other tubulovesicle proteins in resting and histamine-stimulated rabbit parietal cells. Stimulation of isolated gastric glands in the presence of 100 µM histamine and 100 µM 3-isobutyl-1-methylxanthine did not cause a significant increase in soluble Rab11a. H-K-ATPase, Rab11a, Rab25, syntaxin 3, and SCAMPs increased immunoreactivity in stimulus-associated vesicles prepared from rabbits treated with histamine compared with those from ranitidine-treated animals. The large GTPase dynamin was found in both vesicle preparations, but there was no change in amount of immunoreactivity. Immunofluorescence staining of resting and histamine-stimulated primary cultures of parietal cells demonstrated redistribution of H-K-ATPase and Rab11a to F-actin-rich canalicular membranes. Dynamin was present on canalicular membranes in resting and stimulated cells. These results indicate that Rab11a does not cycle off the membrane during the process of tubulovesicle fusion with the secretory canaliculus. Thus Rab11a may remain associated with recycling apical membrane vesicle populations. tubulovesicle proteins; rabbit; dynamin; syntaxin; SNARE proteins