Process outgrowth in oligodendrocytes is mediated by CNP, a novel microtubule assembly myelin protein.
Oligodendrocytes (OLs) extend arborized processes that are supported by microtubules (MTs) and microfilaments. Little is known about proteins that modulate and interact with the cytoskeleton during myelination. Several lines of evidence suggest a role for 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) in mediating process formation in OLs. In this study, we report that tubulin is a major CNP-interacting protein. In vitro, CNP binds preferentially to tubulin heterodimers compared with MTs and induces MT assembly by copolymerizing with tubulin. CNP overexpression induces dramatic morphology changes in both glial and nonglial cells, resulting in MT and F-actin reorganization and formation of branched processes. These morphological effects are attributed to CNP MT assembly activity; branched process formation is either substantially reduced or abolished with the expression of loss-of-function mutants. Accordingly, cultured OLs from CNP-deficient mice extend smaller outgrowths with less arborized processes. We propose that CNP is an important component of the cytoskeletal machinery that directs process outgrowth in OLs.
Lee
John
J
Department of Biochemistry, McGill University, Montreal, Quebec, Canada. johnlee@gene.com
Gravel
Michel
M
Zhang
Rulin
R
Thibault
Pierre
P
Braun
Peter E
PE
D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases / Q000737:chemistry / Q000378:metabolism*; D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D022081:Cell Surface Extensions / Q000201:enzymology*; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003599:Cytoskeleton / Q000201:enzymology; D019281:Dimerization; D005998:Glycine / Q000378:metabolism; D008239:Lysine / Q000378:metabolism; D051379:Mice; D008870:Microtubules / Q000201:enzymology*; D008969:Molecular Sequence Data; D009185:Myelin Proteins / Q000737:chemistry / Q000378:metabolism*; D009836:Oligodendroglia / Q000166:cytology / Q000201:enzymology*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D051381:Rats; D014404:Tubulin / Q000378:metabolism
D000199:Actins; D009185:Myelin Proteins; D014404:Tubulin; D015087:2',3'-Cyclic-Nucleotide Phosphodiesterases; D008239:Lysine; D005998:Glycine