Our world is the same size it’s always been, but so many advances in technology have made the world seem a lot smaller. We can call our brother across the country and video chat with our sister on the other side of the world, all while searching the internet for the lyrics to Snow’s “Informer” (side note…knowing the lyrics won’t help you understand the song AT ALL). Similarly, a neuron’s axons make the nervous system seem a lot smaller too, with their amazing ability to grow very long. Today’s image is from a paper showing how microtubule sliding is involved.
Neurons can transmit signals to far away neurons, thanks to the ability of their axons to grow insanely long. Both actin filaments and microtubules participate in axon growth, with microtubules pushing the growing axon out and actin filaments working directly at the tip of the growing axon, called the growth cone. A recent paper shows the role of microtubule sliding in the initial growth of neurites in fruit fly neurons. Lu and colleagues found that the microtubule motor kinesin-1 drives the sliding of microtubules past one other in order to push out the neuron’s growing projection. This mechanism does not require actin filaments, and is suppressed during maturation of neurons. In the images above, microtubules (green) can be seen pushing against the tip of a growing neurite in a young neuron (membrane of neuron in red and bottom right series). The whole neuron is on the left, and the neurite in the boxed region is shown in the time-lapse images on the right.
Lu, W., Fox, P., Lakonishok, M., Davidson, M., & Gelfand, V. (2013). Initial Neurite Outgrowth in Drosophila Neurons Is Driven by Kinesin-Powered Microtubule Sliding Current Biology, 23 (11), 1018-1023 DOI: 10.1016/j.cub.2013.04.050 Copyright ©2013 Elsevier Ltd. All rights reserved.
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