Spatiotemporal analysis of exocytosis in mouse parotid acinar cells
Spatiotemporal analysis of exocytosis in mouse parotid acinar cells
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DOI：
10.1152/ajpcell.00159.2005
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发表时间：
2005-11-01
影响因子：
5.5
通讯作者：
Giovannucci, DR
中科院分区：
文献类型：
--
作者：
Chen, Y;Warner, JD;Giovannucci, DR
消化系统的外分泌细胞专门响应于神经元和/或激素输入而分泌蛋白质和流体。虽然形态相似，腮腺和胰腺腺泡细胞表现出重要的功能分歧Ca 2+信号转导特性。为了解决是否有消化酶从唾液腺与胰腺的外分泌细胞的胞吐释放的根本差异，我们采用电生理和光学方法，调查的空间和时间特性的酶原含有分泌颗粒融合在单腺泡细胞水平的直接或激动剂诱导的Ca 2+和cAMP的升高。时间分辨的膜电容测量结果表明，两个明显的阶段的胞吐诱导的Ca 2+升高：一个快速激活的初始阶段，不能解决作为个人的融合事件和第二阶段，这是激活后的延迟，增加了阶梯状的方式，增加了cAMP的升高，并可能反映了连续的化合物和多泡融合的酶原含有颗粒。光学测量的胞吐与时间差分成像分析显示，酶原颗粒融合诱导后，类似于200毫秒的最小延迟，最初发生在顶端和基底侧边缘的腺泡细胞，并在强烈的刺激下进行从顶端极更深的区域的细胞内部。酶原颗粒融合似乎协调随后的融合，并产生持久的结构，通常持续几分钟。此外，腮腺切片被用来评估分泌动力学在一个更生理的背景。腮腺腺泡细胞表现出相似和不同的属性相比，更好地研究胰腺腺泡细胞的空间组织和动力学的酶原颗粒的胞吐融合。
Exocrine cells of the digestive system are specialized to secrete protein and fluid in response to neuronal and/or hormonal input. Although morphologically similar, parotid and pancreatic acinar cells exhibit important functional divergence in Ca2+ signaling properties. To address whether there are fundamental differences in exocytotic release of digestive enzyme from exocrine cells of salivary gland versus pancreas, we applied electrophysiological and optical methods to investigate spatial and temporal characteristics of zymogen-containing secretory granule fusion at the single-acinar cell level by direct or agonist-induced Ca2+ and cAMP elevation. Temporally resolved membrane capacitance measurements revealed that two apparent phases of exocytosis were induced by Ca2+ elevation: a rapidly activated initial phase that could not be resolved as individual fusion events and a second phase that was activated after a delay, increased in a staircaselike fashion, was augmented by cAMP elevation, and likely reflected both sequential compound and multivesicular fusion of zymogen-containing granules. Optical measurements of exocytosis with time-differential imaging analysis revealed that zymogen granule fusion was induced after a minimum delay of similar to 200 ms, occurred initially at apical and basolateral borders of acinar cells, and under strong stimulation proceeded from apical pole to deeper regions of the cell interior. Zymogen granule fusions appeared to coordinate subsequent fusions and produced persistent structures that generally lasted several minutes. In addition, parotid gland slices were used to assess secretory dynamics in a more physiological context. Parotid acinar cells were shown to exhibit both similar and divergent properties compared with the better-studied pancreatic acinar cell regarding spatial organization and kinetics of exocytotic fusion of zymogen granules.