Dynamin-2 in nervous system disorders

Abstract

Dynamin-2 is a pleiotropic GTPase whose best-known function is related to membrane scission during vesicle budding from the plasma or Golgi membranes. In the nervous system, dynamin-2 participates in synaptic vesicle recycling, post-synaptic receptor internalization, neurosecretion, and neuronal process extension. Some of these functions are shared with the other two dynamin isoforms. However, the involvement of dynamin-2 in neurological illnesses points to a critical function of this isoform in the nervous system. In this regard, mutations in the dynamin-2 gene results in two congenital neuromuscular disorders. One of them, Charcot-Marie-Tooth disease, affects myelination and peripheral nerve conduction, whereas the other, Centronuclear Myopathy, is characterized by a progressive and generalized atrophy of skeletal muscles, yet it is also associated with abnormalities in the nervous system. Furthermore, single nucleotide polymorphisms located in the dynamin-2 gene have been associated with sporadic Alzheimer's disease. In the present review, we discuss the pathogenic mechanisms implicated in these neurological disorders. Disease-linked dynamin-2 mutations are mainly located in the middle and pleckstrin homology (PH) domains. (a) Dynamin is a multimodular enzyme comprising five highly conserved structural domains: a N-terminal GTPase domain (G-domain) required for binding and hydrolysis of GTP, a middle domain, a PH domain that mediates lipid interaction, a GTPase effector domain (GED) that regulates GTPase activity, which together with the middle domain is involved in dynamin oligomerization. Finally, a C-terminal proline rich domain (PRD) is present, which is required for interaction with SH3-domain-containing proteins. (b) A 'T-shape' dimer appears to be the structural unit of dynamin oligomers (Chappie et al. 2011). In this configuration, the PH domains (yellow) of neighboring monomers act as the 'legs' that insert dynamin into lipid membranes. Each 'stalk' region formed by the middle (green) and GED (red) domains interacts with the other in a crossed fashion, orienting the respective G-domains (blue) in opposite directions. Most of the mutations identified in CNM-patients (at the left) localize at the middle and C-terminal α-helix PH domains, both of which are implicated in dynamin oligomerization. Most of the CMT-linked mutations (at the right) clustering at the N-terminal region of the PH domain are involved in the insertion of dynamin into lipid membranes. Color code for structural domains and letters indicating the mutations are the same as those shown in A. In this diagram, PRD is omitted. © 2013 International Society for Neurochemistry.