Control of isotubulin expression during neuronal differentiation of mouse neuroblastoma and teratocarcinoma cell lines

Abstract Mouse neuroblastoma and teratocarcinoma constitute adequate cellular systems to study the expression of tubulin isoforms during early as well as later steps of neuronal differentiation. Tubulin heterogeneity is extensively analyzed using both isoelectric focusing and two-dimensional electrophoresis. Multipotential embryonal carcinoma cells express mainly one α-tubulin isoform ( α 1 ) and three β-tubulin isoforms: of major one ( β 3 ) and two minor ones ( β 4 and β 5 ). Early events of neuronal differentiation are shown to induce the expression of an additional β-tubulin isoform, β ′ 1 , which is encoded by a specific mRNA. Neurite extension further increases tubulin heterogeneity and leads to the appearance of post-translationally modified isoforms: β ′ 2 in neuroblastoma and α 2 in teratocarcinoma cells. β ′ 2 is shown to derive from the above mentioned β ′ 1 by phosphorylation, while α 2 is probably an acetylated form of the common α 1 -tubulin. These results show that specific changes in tubulin heterogeneity are induced at different steps of neuronal differentiation and are controlled both at the transcriptional (or post-transcriptional) and post-translational levels.