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- Title
Role of SNAREs and H<sup>+</sup>-ATPase in the targeting of proton pump-coated vesicles to collecting duct cell apical membrane.
- Authors
Schwartz, J. H.; Li, G.; Yang, Q.; Suri, V.; Ross, J. J.; Alexander, E. A.
- Abstract
Recycling of H+-ATPase to the apical plasma membrane, mediated by vesicular exocytosis and endocytosis, is an important mechanism for controlling H+ secretion by the collecting duct. We hypothesized that SNAREs (soluble N-ethylmaleimide-sensitive factor attachment proteins) may be involved in the targeting of H+-ATPase-coated vesicles. Using a tissue culture model of collecting duct H+ secretory cells (inner medullary collecting duct (IMCD) cells), we demonstrated that they express the proteins required for SNARE-mediated exocytosis and form SNARE-fusion complexes upon stimulation of H+-ATPase exocytosis. Furthermore, exocytic amplification of apical H+-ATPase is sensitive to clostridial toxins that cleave SNAREs and thereby inhibit secretion. Thus, SNAREs are critical for H+-ATPase cycling to the plasma membrane. The process in IMCD cells has a feature distinct from that of neuronal cells: the SNARE complex includes and requires the vesicular cargo (H+-ATPase) for targeting. Using chimeras and truncations of syntaxin 1, we demonstrated that there is a specific cassette within the syntaxin 1 H3 domain that mediates binding of the SNAREs and a second distinct H3 region that binds H+-ATPase. Utilizing point mutations of the B1 subunit of the H+-ATPase, we document that this subunit contains specific targeting information for the H+-ATPase itself. In addition, we found that Munc-18-2, a regulator of exocytosis, plays a multifunctional role in this system: it regulates SNARE complex formation and the affinity of syntaxin 1 for H+-ATPase.Kidney International (2007) 72, 1310–1315; doi:10.1038/sj.ki.5002500; published online 5 September 2007
- Subjects
CELLS; ADENOSINE triphosphatase; TISSUE culture; ABSORPTION (Physiology); CELL membranes
- Publication
Kidney International, 2007, Vol 72, Issue 11, p1310
- ISSN
0085-2538
- Publication type
Article
- DOI
10.1038/sj.ki.5002500