It has become clear that the products of several of the earliest identified myelin protein genes perform functions that extend beyond the myelin sheath. Interestingly, these myelin proteins, which comprise proteolipid protein, 2′,3′-cyclic nucleotide 3′-phosphodiesterase and the classic and golli MBPs (myelin basic proteins), play important roles during different stages of oligodendroglial development. These non-myelin-related functions are varied and include roles in the regulation of process outgrowth, migration, RNA transport, oligodendrocyte survival and ion channel modulation. However, despite the wide variety of cellular functions performed by the different myelin genes, the route by which they achieve these many functions seems to converge upon a common mechanism involving Ca2+ regulation, cytoskeletal rearrangements and signal transduction. In the present review, the newly emerging functions of these myelin proteins will be described, and these will then be discussed in the context of their contribution to oligodendroglial development.
Keywords: amyloid β-peptide (Aβ), calmodulin (CaM), central nervous system (CNS), extracellular matrix (ECM), oligodendrocyte (OL), proteolipid protein (PLP)
Abbreviations: Aβ, amyloid β-peptide, AMPA, α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid, CaM, calmodulin, CNP, 2′,3′-cyclic nucleotide 3′-phosphodiesterase, CNS, central nervous system, ECM, extracellular matrix, ER, endoplasmic reticulum, GIP, golli-interacting protein, KO, knockout, MAG, myelin-associated glycoprotein, MARCKS, myristoylated alanine-rich C-kinase substrate, MBP, myelin basic protein, MS, multiple sclerosis, OL, oligodendrocyte, OPC, OL precursor cell, PDGF, platelet-derived growth factor, PLP, proteolipid protein, PNS, peripheral nervous system, RNAi, RNA interference, SH3 domain, Src homology 3 domain, SOCC, store-operated Ca2+ channel, VOCC, voltage-operated Ca2+ channel