James D Jontes | PubMed Health

PubMed2006

Selective stabilization and synaptic specificity: a new cell-biological model.

How are appropriate connections between neurons sorted from the overwhelming surplus of potential, yet inappropriate, connections? Despite the apparently improbable nature of the process, brains wire themselves with a high degree of reproducibility that has been conserved across evolutionary history. Here, we outline a viable cell-biological model for generating synaptic specificity that features selection of nascent synapses based on adhesion and recognition. This process uses the highly dynamic and stochastic nature of intracellular trafficking to generate reproducible patterns of synaptic connectivity.

Animals↗

PubMed2004

In vivo trafficking and targeting of N-cadherin to nascent presynaptic terminals.

N-cadherin is a prominent component of developing and mature synapses, yet very little is known about its trafficking within neurons. To investigate N-cadherin dynamics in developing axons, we used in vivo two-photon time-lapse microscopy of N-cadherin--green fluorescent protein (Ncad-GFP), which was expressed in Rohon-Beard neurons of the embryonic zebrafish spinal cord. Ncad-GFP was present as either stable accumulations or highly mobile transport packets. The mobile transport packets were of two types: tubulovesicular structures that moved preferentially in the anterograde direction and discrete-punctate structures that exhibited bidirectional movement. Stable puncta of Ncad-GFP accumulated in the wake of the growth cone with a time course. Colocalization of Ncad-GFP puncta with synaptic markers suggests that N-cadherin is a very early component of nascent synapses. Expression of deletion mutants revealed a potential role of the extracellular domain in appropriate N-cadherin trafficking and targeting. These results are the first to characterize the trafficking of a synaptic cell-adhesion molecule in developing axons in vivo. In addition, we have begun to investigate the cell biology of N-cadherin trafficking and targeting in the context of an intact vertebrate embryo.

Animals↗