Neurofilament function and dysfunction: involvement in axonal growth and neuronal disease.

Neurofilaments make up the major intermediate filament system in mature neurons. Recent studies demonstrate that neurofilaments in vivo are obligate heteropolymers and are required for proper radial growth of axons. Furthermore, forced over-expression of neurofilament subunits in transgenic mice shows that abnormal accumulation and assembly of neurofilaments, similar to that commonly found in human motor neuron disease can directly cause motor neuron dysfunction.