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DIFFERENTIATED NEURONS RETAIN THE CAPACITY TO GENERATE AXONS FROM DENTRITES. Bradke, F., Dotti*, C., *Cell Biology Program, EMBL, Heidelberg, Germany, and Departments of Anatomy and biochemistry and Biophysics University of California, San Francisco, Current Biology, 10, 1467-1470, (2000)

Abstract:
Cutting the axon of a morphologically polarized neuron (stage 3) close to the cell body causes another neurite to grow as an axon. Stage 3 neurons still lack molecular segregation of axonal and dendritic proteins, however. Axonal and dendritic compartments acquire their distinct composition at stage 4 (4–5 days in culture), when proteins such as the microtubule-associated protein 2 (MAP-2) and the glutamate receptor subunit GluR1 localize to the dendrites and disappear from the axon. We investigated whether cultured hippocampal neurons retained axon/dendrite plasticity after axons and dendrites have created their distinct cytoskeletal architecture and acquired their specific membrane composition. We found that axotomy of stage 4 neurons transformed a dendrite into an axon. Using axonal and dendritic markers, we tested whether cytoskeletal changes could cause similar transformations, and found that actin depolymerization induced multiple axons in unpolarized neurons. Moreover, depletion of actin filaments from both morphologically and molecularly polarized cells also resulted in the growth of multiple axons from pre-existing dendrites. These results imply that dendrites retain the potential to become axons even after molecular segregation has occurred and that the dendritic fate depends on the integrity of the actin cytoskeleton. © 2000 Elsevier Science Ltd. All rights reserved.

Link to Paper

Materials & Methods:
"For interval recordings, cells grown on cellocate coverslips were put into a petri dish with coverslip glass bottom (MatTek Corporation) filled with medium equilibrated to atmospheric concentrations of gases."

Microscopic Technique:
low intensity microscopy

Cell Type(s):
primary hippocampal neurons