Honda Yu, Tsuchiya Kenta, Sumiyoshi Eisuke, Haruta Nami, Sugimoto Asako
Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan.
Laboratory of Developmental Dynamics, Graduate School of Life Sciences, Tohoku University, Sendai 980-8577, Japan
J Cell Sci. 2017 May 1;130(9):1652-1661. doi: 10.1242/jcs.200923. Epub 2017 Mar 16.
Microtubules (MTs) are polymers composed of α- and β-tubulin heterodimers that are generally encoded by genes at multiple loci. Despite implications of distinct properties depending on the isotype, how these heterodimers contribute to the diverse MT dynamics remains unclear. Here, by using genome editing and depletion of tubulin isotypes following RNAi, we demonstrate that four tubulin isotypes (hereafter referred to as α1, α2, β1 and β2) cooperatively confer distinct MT properties in early embryos GFP insertion into each isotype locus reveals their distinct expression levels and MT incorporation rates. Substitution of isotype coding regions demonstrates that, under the same isotype concentration, MTs composed of β1 have higher switching frequency between growth and shrinkage compared with MTs composed of β2. Lower concentration of β-tubulins results in slower growth rates, and the two α-tubulins distinctively affect growth rates of MTs composed of β1. Alteration of ratio and concentration of isotypes distinctively modulates both growth rate and switching frequency, and affects the amplitude of mitotic spindle oscillation. Collectively, our findings demonstrate that MT dynamics are modulated by the combination (ratio and concentration) of tubulin isotypes with distinct properties, which contributes to create diverse MT behaviors .
微管（MTs）是由α-和β-微管蛋白异二聚体组成的聚合物，这些异二聚体通常由多个基因座上的基因编码。尽管根据同种型不同会有不同的特性，但这些异二聚体如何促成微管的多种动力学仍不清楚。在这里，通过使用基因组编辑和RNA干扰后微管蛋白同种型的缺失，我们证明了四种微管蛋白同种型（以下称为α1、α2、β1和β2）在早期胚胎中协同赋予微管不同的特性。将绿色荧光蛋白插入每个同种型基因座可揭示它们不同的表达水平和微管掺入率。同种型编码区的替换表明，在相同的同种型浓度下，与由β2组成的微管相比，由β1组成的微管在生长和收缩之间的转换频率更高。较低浓度的β-微管蛋白导致生长速度较慢，并且两种α-微管蛋白对由β1组成的微管的生长速度有不同的影响。同种型比例和浓度的改变对生长速度和转换频率都有独特的调节作用，并影响有丝分裂纺锤体振荡的幅度。总的来说，我们的研究结果表明，微管动力学是由具有不同特性的微管蛋白同种型的组合（比例和浓度）调节的，这有助于产生多种微管行为。
