Abstract
Gastric acid secretion by parietal cells requires trafficking and exocytosis of H/K-ATPase-rich tubulovesicles (TVs) toward apical membranes in response to histamine stimulation via cyclic AMP elevation. Here, we found that TRPML1 (ML1), a protein that is mutated in type IV mucolipidosis (ML-IV), is a tubulovesicular channel essential for TV exocytosis and acid secretion. Whereas ML-IV patients are reportedly achlorhydric, transgenic overexpression of ML1 in mouse parietal cells induced constitutive acid secretion. Gastric acid secretion was blocked and stimulated by ML1 inhibitors and agonists, respectively. Organelle-targeted Ca2+ imaging and direct patch-clamping of apical vacuolar membranes revealed that ML1 mediates a PKA-activated conductance on TV membranes that is required for histamine-induced Ca2+ release from TV stores. Hence, we demonstrated that ML1, acting as a Ca2+ channel in TVs, links transmitter-initiated cyclic nucleotide signaling with Ca2+-dependent TV exocytosis in parietal cells, providing a regulatory mechanism that could be targeted to manage acid-related gastric diseases.
Original language | English (US) |
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Pages (from-to) | 262-273.e6 |
Journal | Developmental Cell |
Volume | 41 |
Issue number | 3 |
DOIs | |
State | Published - May 8 2017 |
Externally published | Yes |
Keywords
- Ca release
- TRPML1
- cAMP
- exocytosis
- membrane trafficking
- tubulovesicle
ASJC Scopus subject areas
- Molecular Biology
- General Biochemistry, Genetics and Molecular Biology
- Developmental Biology
- Cell Biology