Researchers have identified the locking mechanism that allows some neurons to form synapses to pass along essential information. Mutations of genes that produce a critical cell-adhesion molecule involved in the work were previously linked to autism.
The discovery -- captured with fluorescent imaging of excitatory neurons harvested from rat pups shortly after birth and studied in culture as they continued to develop -- is described in a paper placed online May 18 ahead of formal publication in the open-access journal Neural Development.
"We've caught two neuronal cells in the act of forming a synapse," said principle investigator Philip Washbourne, professor of biology at the University of Oregon. He describes the cell-adhesion neuroligin proteins on the membranes of receptor neurons as "molecular Velcro."
The research team of six UO and University of California, Davis, scientists found one of many finger-like filopodia, or spines, that reach out from one neuron is nabbed by neuroligin molecules on the membrane of another neuron. In turn, neuroligins recruit at least two other key proteins (PSD-95 and NMDA receptors) to begin building a scaffold to hold the synapse components in place. The moment of locking is captured in a video (link below) that will appear with the paper's final version at the journal's Web site.
Two neuroligin family members (3 and 4) have been linked to autism in the last decade.
"Chemical synapses are the primary means for transmitting information from one neuron to the next," said Washbourne, who is a member of the UO's Institute of Neuroscience. "Synapses are initially formed during development of the nervous system, and formation of appropriate synapses is crucial for establishing neuronal circuits that underlie behavior and cognition. Minor irregularities can lead to developmental disorders such as autism and mental retardation, and they may contribute to psychological disorders."
|Contact: Jim Barlow|
University of Oregon