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Published online: 25 November 2009 | doi:10.1038/nchina.2009.226

Developmental neuroscience: Full speed ahead

Felix Cheung

Introduction

© (2009) Nature Neuroscience

The formation of synapses, or synaptogenesis, is an incredibly important process — especially in early development because it directly affects brain performance later in life. Abnormalities in synaptogenesis can also lead to brain disorders, such as autism and mental retardation. Jun Xia and co-workers at the Hong Kong University of Science and Technology¹ have discovered a glycoprotein that can speed up synaptogenesis in the early stage of cultured rat hippocampal neurons.

Thrombospondin 1 (TSP1) is a protein secreted by various types of brain cells, including astrocytes. The researchers applied TSP1 to cultured hippocampal neurons for various periods up to 17 days in vitro (DIV). They then used the excitatory synapse marker PSD-95 and the presynaptic terminal marker synaptin-1 to highlight the formation of full synapses (see image).

The researchers found that incubation of TSP1 at 5–8 DIV led to a 36% increase in the density of full synapses. Surprisingly, however, treating cultured neurons with TSP1 for longer periods — 5–10 DIV, 5–14 DIV and 14–17 DIV — had little effect on synapse density. The result suggests that TSP1 accelerates the speed of synaptogenesis, but does not increase the final density of synapses in mature neurons.

The underlying mechanism by which TSP1 induces synaptogenesis has yet to be determined, but the researchers suspect that TSP1 may share a common mechanism with neurexin 1 — another protein that has similar effects on synapse formation.

The authors of this work are from:
Department of Biochemistry, Hong Kong University of Science and Technology, Hong Kong, China.

Reference

1. Xu, J, Xiao, N. & Xia, J. Thrombospondin 1 accelerates synaptogenesis in hippocampal neurons through neuroligin 1. Nature Neurosci. doi:10.1038/nn.2459 (2009). | Article | OpenURL