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Phosphatidylinositol‐4,5‐bisphosphate‐dependent Facilitation of the ATP‐dependent Secretory Activity in Mouse Pituitary Cells
Author(s) -
Sedej Simon,
Gurung Iman Singh,
Binz Thomas,
Rupnik Marjan
Publication year - 2009
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.2008.04002.x
Subject(s) - exocytosis , secretory vesicle , vesicle , phosphatidylinositol , microbiology and biotechnology , phosphatidylinositol 4,5 bisphosphate , priming (agriculture) , cytosol , chemistry , intracellular , pi , lipid bilayer fusion , vesicle fusion , biology , endocrinology , medicine , biochemistry , synaptic vesicle , secretion , signal transduction , membrane , enzyme , germination , botany
Phosphatidylinositol‐4, 5‐bisphosphate [PI(4,5)P 2 ] has been implicated in the priming of large dense‐core vesicles in many secretory cells; however, its role in the Ca 2+ ‐dependent secretory activity in pituitary cells remains elusive. We assessed the effect of elevated intracellular PI(4,5)P 2 on the kinetics of Ca 2+ ‐dependent exocytosis, using a whole‐cell patch‐clamp technique in wild‐type mouse melanotrophs from fresh pituitary tissue slices. We found that 1 μmol/L PI(4,5)P 2 significantly increased Ca 2+ ‐dependent exocytosis of vesicles that need to go through ATP‐dependent reactions; however, the exocytosis of release‐ready vesicles (ATP‐independent release) and voltage‐activated Ca 2+ currents remained unaffected. We suggest that PI(4,5)P 2 increases the size of the readily releasable vesicle pool by regulating the effectiveness of vesicular mobilization and fusion in an ATP‐dependent manner.