First published online February 22, 2006
Journal of Cell Science 119, 503e (2006)
© The Company of Biologists Limited
Exocyst implicated in myelin wrap
The myelin sheath that insulates neurons is essential for efficient neurotransmission. In the CNS, it is synthesised by neighbouring oligodendrocyte cells. Quite how these sort and assemble the various lipids and proteins that make up the membranous sheath is unclear. On p. 807, Steven Pfeiffer and co-workers implicate components of an octomeric complex termed the exocyst in the process. The exocyst helps recruit transport vesicles to areas of polarised membrane growth in various cells. Pfeiffer and co-workers observe that the exocyst components Sec8 and Sec6 are present in oligodendrocytes. Moreover, they find that Sec8 colocalises with the major myelin protein OSP (also known as claudin 11) and CASK, a scaffold protein that recruits proteins to synaptic junctions. The authors go on to show that overexpression of Sec8 promotes formation of myelin-like membrane and oligodendrocyte differentiation but that, conversely, knocking down Sec8 by RNAi inhibits this. They conclude that the exocyst is required for polarised delivery of vesicles carrying myelin components to the oligodendrocyte surface, suggesting that Sec8-CASK interactions promote their transport along microtubules.
Related articles in JCS:
- A role for Sec8 in oligodendrocyte morphological differentiation
- Mihaela Anitei, Marius Ifrim, Marie-Ann Ewart, Ann E. Cowan, John H. Carson, Rashmi Bansal, and Steven E. Pfeiffer
JCS 2006 119: 807-818.
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