| Abstract No.: | B-A2008 |
| Country: | Canada |
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| Title: | SIGNALING MECHANISMS THAT REGULATE OLIGODENDROCYTE PRECURSOR MIGRATION |
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| Authors/Affiliations: | 1 Sathyanath Rajasekharan*; 1 James Correia; 1 Jack Antel; 1 Timothy Kennedy;
1 McGill University, Montreal, QC, Canada
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| Content: | Objective: During development oligodendrocyte precursors (OPCs) migrate to target regions of the CNS where they eventually differentiate into mature, myelinating oligodendrocytes. The secreted guidance cue Netrin-1, expressed by the floor plate cells of the embryonic spinal cord, acts as a chemorepellent for OPCs, promoting their dispersal to dorsal regions of the spinal cord. We investigated the intracellular mechanisms by which netrin-1 induces OPC repulsion, and examined the interaction between the netrin-1 receptor deleted in colorectal cancer (DCC) with components of the actin cytoskeletal machinery. In particular, we focussed on the Rho family of small GTPases, RhoA, Rac1 and Cdc42.
Methods: OPCs were purified from newborn rat cortices using a mixed glial culture shake-off method. OPC migration was investigated using a Boyden chamber assay. Pharmacological inhibitors of ROCK (Y27632 and H1152), an effector of RhoA, were used to test the requirement for RhoA activity in netrin-1-mediated repulsion of OPCs. Biochemical pulldown methods were used to investigate changes in GTPase activity in OPCs stimulated with netrin-1.
Results: Inhibition of ROCK disrupted netrin-1-induced chemorepulsion of OPCs. In addition, treatment of OPCs with these inhibitors also disrupted netrin-1 induced process retraction, a characteristic morphological change accompanying repulsion.
Conclusion: These findings provide evidence that RhoA is a critical downstream component of the signalling pathway activated by netrin-1 in OPCs. To obtain a more complete picture of the signals influencing OPC migration, we are currently investigating how Rac1 and Cdc42 activity complements the activation of RhoA. |
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