SNARE complex proteins, including the cognate pair VAMP-2 and syntaxin-4, are expressed in cultured oligodendrocytes

Myelin membrane synthesis in the CNS by oligodendrocytes (OLs) involves dir ected intracellular transport and targeting of copious amounts of specializ ed lipids and proteins over a relatively short time span. As in other plasm a membrane-directed fusion, this process is expected to use specific traffi cking and vesicle fusion proteins characteristic of the SNARE model. We hav e investigated the developmental expression of SNARE proteins in highly enr iched primary cultures of OLs at discrete stages of differentiation. VAMP-2 /synaptobrevin-2, syntaxin-2 and -4, nsec-1/munc-1 8-1, Rab3a, synaptophysi n, and synapsin were expressed. During differentiation, expression of the v esicular SNARE VAMP-2, the small GTP-binding protein Rab3a, and the target SNARE syntaxin-4 were up-regulated. VAMP-2 and Rab3 proteins detected immun ocytochemically in cultured OLs were localized within the developing proces s network; in situ anti-VAMP-2 antibody stained the perikarya of rows of ce lls with the distribution and appearance of OLs. We discuss the potential i nvolvement of SNARE complex proteins in a plasma membrane-directed transpor t mechanism targeting nascent myelin vesicles to the forming myelin sheath.