MARC U* STAR Program, University of California, Riverside, California, USA.
J Neurochem. 2011 Mar;116(5):909-15. doi: 10.1111/j.1471-4159.2010.07018.x. Epub 2011 Jan 7.
Astrocytes possess much of the same exocytotic protein machinery as neurons do and can release various gliotransmitters stored in their secretory vesicles. An essential component of this exocytotic machinery is the vesicle-associated membrane protein synaptobrevin 2 (Sb2). In order to assess whether vesicular age plays a role in determining the intracellular location of vesicles in astrocytes, we generated a fluorescent chimeric form of Sb2. We appended the Sb2 cytosolic N-terminus with the fluorescent 'timer' protein DsRedE5, which changes its fluorescence emission from green to red as it ages. We found that Sb2-containing vesicles in astrocytes segregate and localize intracellularly in an age dependent manner. Younger vesicles predominately localize at the periphery of cell somata and processes, while older vesicles predominately locate at the central portion of the cell body. These findings raise the notion that there might be differential astrocyte-neuron signaling at sites away or at the tripartite synapse that could be modulated by the age of vesicles and/or their cargo.
星形胶质细胞拥有与神经元相似的胞吐蛋白机制，并能释放储存在其分泌小泡中的各种神经胶质递质。这种胞吐机制的一个重要组成部分是囊泡相关膜蛋白突触融合蛋白 2（Sb2）。为了评估囊泡的年龄是否在决定星形胶质细胞中囊泡的细胞内位置方面发挥作用，我们生成了荧光嵌合形式的 Sb2。我们在 Sb2 的胞质 N 端添加了荧光“计时器”蛋白 DsRedE5，随着其年龄的增长，它的荧光发射从绿色变为红色。我们发现星形胶质细胞中的 Sb2 包含的囊泡以依赖年龄的方式进行分隔和定位。年轻的囊泡主要位于细胞体和突起的外周，而较老的囊泡主要位于细胞体的中央部分。这些发现提出了这样一种观点，即在远离三突触复合体或在三突触复合体处可能存在着不同的星形胶质细胞-神经元信号传递，而这种信号传递可能会被囊泡及其货物的年龄所调节。
