The small GTPase RhoA causes growth cone collapse and halts axon growth, therebyinhibitingregeneration of injured nerves. In contrast, RhoA has also been shown to promote growth cone advanceunder specific circumstances, and is important for guidance in growth cone motility. The broad objective ofthis proposal is to deduce how,through precise control of RhoA activation kinetics and localization, thisprotein can stimulate opposite cell behaviors. To resolve this conflict, we will utilize a biosensor to directlyvisualize the activation of RhoA in growing and retracting neurons, and manipulate microtubules to probeunderlying mechanisms in RhoA signaling.
Specific Aim 1 will determine the spatiotemporal dynamics ofRhoA activation in growth cones during both extension and collapse, using novel image processing tools togenerate a dynamic map of RhoA activation with subsecond and submicron resolution. The microtubulecytoskeleton is a master regulator of growth cone motility and guidance; it is both a major downstream targetand upstream activator of RhoA.
Specific Aim 2 will determine the relationship between RhoA activation andmicrotubule distribution and dynamics in growth cones.RelevanceIn addition to nervous system regenerationfailure, there are a host of severe and debilitating developmentaldiseases in which axon growth fails. Understanding the basic mechanism behind growth cone motility andaxon extension can lead to the development of new treatments for nervous system injury and disease.
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| Berginski, Mathew E; Vitriol, Eric A; Hahn, Klaus M et al. (2011) High-resolution quantification of focal adhesion spatiotemporal dynamics in living cells. PLoS One 6:e22025 |
