Functions of Myosin Motor Proteins in the Nervous System

Abstract

The myosin superfamily consists of 24 classes of actin-based molecular motors that carry out a diverse array of cellular functions ranging from cell motility and morphology to cytokinesis, signal transduction, membrane trafficking, RNA and protein localization. The development and functioning of the nervous system strongly depends on the proper establishment of complex networks of neurons with highly specialized morphologies and molecular composition. Thus, it is not at all surprising that multiple classes of myosin motors are expressed in the nervous system, including classes I, II, III, V, VI, VII, IX, X, XV, and XVI. This review discusses the current knowledge on myosin functions in both neurons and specific sensory neurons, the hair cells of the inner ear, and the photoreceptors in the eye. The role of myosin II in growth cone motility and neurite outgrowth is the best characterized myosin function in neurons. However, there is increasing evidence that different myosin motors are also involved in protein and organelle trafficking underlying synaptic function. Multiple myosin motors have been localized to hair cells and photoreceptors and associated with genetic diseases; however, a future challenge will be a better characterization of the cellular functions of these various motor proteins.