Sabo Shasta L, Gomes Raquel A, McAllister A Kimberley
Center for Neuroscience, University of California, Davis, Davis, California 95616, USA.
J Neurosci. 2006 Oct 18;26(42):10813-25. doi: 10.1523/JNEUROSCI.2052-06.2006.
What determines where synapses will form along an axon or how proteins are deposited at nascent synapses remains unknown. Here, we show that the initial formation of presynaptic terminals occurs preferentially at predefined sites within the axons of cortical neurons. Time-lapse imaging of synaptic vesicle protein transport vesicles (STVs) indicates that STVs pause repeatedly at these sites, even in the absence of neuronal or glial contact. Contact with a neuroligin-expressing non-neuronal cell induces formation of presynaptic terminals specifically at these STV pause sites. Remarkably, formation of stable contacts with dendritic filopodia also occurs selectively at STV pause sites. Although it is not yet known which molecules comprise the predefined sites, STV pausing is regulated by cues that affect synaptogenesis. Overall, these data are consistent with the hypothesis that regulation of STV pausing might be an important mechanism for accumulation of presynaptic proteins at nascent synapses and support a new model in which many en passant synapses form specifically at predefined sites in young axons.
是什么决定了突触会沿着轴突在何处形成，或者蛋白质是如何在新生突触处沉积的，目前尚不清楚。在这里，我们表明突触前终末的初始形成优先发生在皮质神经元轴突内的预定义位点。对突触小泡蛋白运输囊泡（STV）的延时成像表明，即使在没有神经元或神经胶质细胞接触的情况下，STV也会在这些位点反复暂停。与表达neuroligin的非神经元细胞接触会诱导突触前终末专门在这些STV暂停位点形成。值得注意的是，与树突状丝状伪足形成稳定接触也选择性地发生在STV暂停位点。虽然尚不清楚哪些分子构成了预定义位点，但STV的暂停受影响突触形成的线索调控。总体而言，这些数据与以下假设一致，即STV暂停的调控可能是突触前蛋白在新生突触处积累的重要机制，并支持一种新模型，即许多旁触突触专门在年轻轴突的预定义位点形成。
