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

Abstract 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 β IV ‐tubulin from post‐natal ( p ) day P10 suggesting that p25α/TPPP plays an important role for tubulin‐related transport in developing, myelinating oligodendrocytes.