Tubulin Polymerization-Promoting Protein (TPPP/p25) is Critical for Oligodendrocyte Differentiation

TPPP/p25, a recently identified tubulin polyinerization-promoting protein (TPPP), is expressed mainly in myelinating oligodendrocytes of the CNS. Here, we show that TPPP/p25 is strongly upregulated during the differentiation of primary oligodendrocyte cells as well as the CG-4 cell line. The microRNA expression profile of CG-4 cells before and after induction of differentiation was established and revealed differential regulation of a limited subset of microRNAs. miR-206, a microRNA predicted to target TPPP/p25 was not detected in oligodendrocytes. Overexpression of miR-206 led to downreg-ulation of TPPP/p25 resulting in inhibition of differentiation. Transfection of siRNAs against TPPP/p25 also inhibited cell differentiation and promoted cell proliferation, providing evidence for an important role of TPPP/p25 during oligodendrogenesis. These results support an essential role for TPPP/p25 in oligodendrocyte differentiation likely via rearrangement of the microtubule system during the process elongation prior to the onset of myelination. (C) 2009 Wiley-Liss, Inc.