Elucidation of the separate roles of myosins IIA and IIB during neurite outgrowth, adhesion and retraction.

The functions of nonmuscle myosin isoforms are key to an understanding of process outgrowth from nerve cells during animal development. Despite considerable structural similarity, myosin IIA and myosin IIB play distinct and complementary roles during the actin-based mechanisms of nerve process extension. An overview is given of evidence that implicates myosin IIB as the motor essential for nerve process outgrowth and myosin IIA both as the motor required to maintain cell adhesion to the substrate as well as the motor required to power retraction of the nerve cell process. These actions are placed in context within a model for nerve process extension that is consistent with many observations in the literature and provides testable hypotheses regarding possible roles for these nonmuscle myosin motors. The relevance of a fundamental understanding of the mechanisms underpinning nerve cell process extension to the application of nanotechnology in this area is also discussed.