Gi Protein Modulation of the Potassium Channel TASK-2 Mediates Vesicle Osmotic Swelling to Facilitate the Fusion of Aquaporin-2 Water Channel Containing Vesicles.
Cells
; 7(12)2018 Dec 19.
Article
em En
| MEDLINE
| ID: mdl-30572630
Vesicle fusion is a fundamental cell biological process similar from yeasts to humans. For secretory vesicles, swelling is considered a step required for the expulsion of intravesicular content. Here this concept is revisited providing evidence that it may instead represent a general mechanism. We report the first example that non-secretory vesicles, committed to insert the Aquaporin-2 water channel into the plasma membrane, swell and this phenomenon is required for fusion to plasma membrane. Through an interdisciplinary approach, using atomic force microscope (AFM), a fluorescence-based assay of vesicle volume changes and NMR spectroscopy to measure water self-diffusion coefficient, we provide evidence that Gi protein modulation of potassium channel TASK-2 localized in AQP2 vesicles, is required for vesicle swelling. Estimated intravesicular K⺠concentration in AQP2 vesicles, as measured by inductively coupled plasma mass spectrometry, was 5.3 mM, demonstrating the existence of an inwardly K⺠chemical gradient likely generating an osmotic gradient causing vesicle swelling upon TASK-2 gating. Of note, abrogation of K⺠gradient significantly impaired fusion between vesicles and plasma membrane. We conclude that vesicle swelling is a potentially important prerequisite for vesicle fusion to the plasma membrane and may be required also for other non-secretory vesicles, depicting a general mechanism for vesicle fusion.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Idioma:
En
Revista:
Cells
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Itália
País de publicação:
Suíça