Microtubules (MTs) are polymers composed of α- and β-tubulin heterodimers, which are generally encoded by multiple gene loci. Despite implications of distinct properties of isotypes, how they contribute to diverse MT dynamics in vivo remains unclear. Here, using genome editing and RNAi depletion of tubulin isotypes, we demonstrate that four tubulin isotypes (hereafter α1, α2, β1 and β2) cooperatively confer distinct MT properties in Caenorhabditis elegans 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, β1-composed MTs have higher switching frequency between growth and shrinkage than β2-composed MTs. Lower concentration of β-tubulins results in slower growth rates, and the two α-tubulins distinctively affect growth rates of β1-composed MTs. 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 is modulated by composition (ratio and concentration) of tubulin isotypes with distinct properties, which contributes to create diverse MT behaviors in vivo.
- Received December 22, 2016.
- Accepted March 13, 2017.
- © 2017. Published by The Company of Biologists Ltd