Scientists at HHMI’s Janelia Research Campus have discovered a new kind of synapse in the tiny hairs on the surface of neurons.
The commonly overlooked protrusions called primary cilia contain special junctions that act as a shortcut for sending signals quickly and directly to the cell’s nucleus, inducing changes to the cell’s chromatin that forms chromosomes.
“This special synapse represents a way to change what is being transcribed or made in the nucleus, and that changes whole programs,” says Janelia Senior Group Leader David Clapham, whose team led the new research published September 1 in Cell. The effects in the cell are not just short-term, he adds — some can be long-term. “It is like a new dock on a cell that gives express access to chromatin changes, and that is very important because chromatin changes so many aspects of the cell.”
Synapses are well-known to occur between the axon of one neuron and the dendrites of other neurons, but had never been observed between the neuron’s axon and the primary cilium. Janelia’s high-resolution microscopes and innovative tools enabled the researchers to peer deep into the cell and cilia to observe the synapse, the signaling cascade inside the cell, and the changes in the nucleus.
The discovery of the ciliary synapse could help scientists better understand how long-term changes in cells are communicated. The cilia, which extend from the cell’s interior, near the nucleus, to the exterior, could provide a faster and more selective way for cells to carry out these long-term changes, Clapham says.
“This was all about seeing — and Janelia enables us to see like we couldn’t see before,” Clapham says. “It opens up a lot of possibilities we hadn’t thought of.”
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