P25α/Tubulin polymerization promoting protein expression by myelinating oligodendrocytes of the developing rat brain

P25α/tubulin polymerization promoting protein (TPPP) is a brain specific phosphoprotein that displays microtubule bundling activity. In the mature brain, p25α/TPPP distributes to oligodendrocytes and choroid plexus epithelium. We mapped the spatial and temporal distribution of p25α/TPPP in the developing rat brain. Having localized its expression to neuronal tissue by Western blot analyses, the distribution of p25α/TPPP to developing oligodendrocytes was confirmed using a specific antibody. In the pre-natal and post-natal brain, p25α/TPPP was localized to the perinuclear cytoplasm of myelinating oligodendrocytes from embryonic (E) day E20 as verified from cellular co-localization with 2′,3′-cyclic nucleotide 3′-phosphodiesterase (CNP). Oligodendrocyte progenitor cells and pre-myelinating oligodendrocytes identified by the expression of NG2 proteoglycan and CD9, respectively, both failed to contain p25α/TPPP. In contrast, P25α/TPPP co-localized with βIV-tubulin from post-natal (p) day P10 suggesting that p25α/TPPP plays an important role for tubulin-related transport in developing, myelinating oligodendrocytes.