Guček Alenka, Jorgačevski Jernej, Górska Urszula, Rituper Boštjan, Kreft Marko, Zorec Robert
a Laboratory of Neuroendocrinology-Molecular Cell Physiology ; Institute of Pathophysiology ; Faculty of Medicine ; University of Ljubljana ; Ljubljana , Slovenia.
Channels (Austin). 2015;9(2):96-101. doi: 10.1080/19336950.2015.1007825.
In regulated exocytosis vesicular and plasma membranes merge to form a fusion pore in response to stimulation. The nonselective cation HCN channels are involved in the regulation of unitary exocytotic events by at least 2 mechanisms. They can affect SNARE-dependent exocytotic activity indirectly, via the modulation of free intracellular calcium; and/or directly, by altering local cation concentration, which affects fusion pore geometry likely via electrostatic interactions. By monitoring membrane capacitance, we investigated how extracellular cation concentration affects fusion pore diameter in pituitary cells and astrocytes. At low extracellular divalent cation levels predominantly transient fusion events with widely open fusion pores were detected. However, fusion events with predominately narrow fusion pores were present at elevated levels of extracellular trivalent cations. These results show that electrostatic interactions likely help determine the stability of discrete fusion pore states by affecting fusion pore membrane composition.
在调节性胞吐作用中，囊泡膜和质膜响应刺激而融合形成融合孔。非选择性阳离子HCN通道至少通过两种机制参与单一胞吐事件的调节。它们可以通过调节细胞内游离钙间接影响依赖SNARE的胞吐活性；和/或直接通过改变局部阳离子浓度来影响，这可能通过静电相互作用影响融合孔的几何形状。通过监测膜电容，我们研究了细胞外阳离子浓度如何影响垂体细胞和星形胶质细胞中的融合孔直径。在低细胞外二价阳离子水平下，主要检测到具有广泛开放融合孔的短暂融合事件。然而，在细胞外三价阳离子水平升高时，存在主要具有狭窄融合孔的融合事件。这些结果表明，静电相互作用可能通过影响融合孔膜组成来帮助确定离散融合孔状态的稳定性。
