Kinesin-13 regulates the quantity and quality of tubulin inside cilia.
Bottom Line: Loss of both Kin13Bp and Kin13Cp resulted in slow cell multiplication and motility, overgrowth of cell body microtubules, shortening of cilia, and synthetic lethality with either paclitaxel or a deletion of MEC-17/ATAT1, the α-tubulin acetyltransferase.The mutant cilia beat slowly and axonemes showed reduced velocity of microtubule sliding.Thus kinesin-13 positively regulates the axoneme length, influences the properties of ciliary tubulin, and likely indirectly, through its effects on the axonemal microtubules, affects the ciliary dynein-dependent motility.
Affiliation: Department of Cellular Biology, University of Georgia, Athens, GA 30602;Show MeSH
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Mentions: We used Western blotting to quantify the levels of modified and total tubulin in the wild-type and 13BC-KO cilia. The 13BC-KO and wild-type cilia showed a nearly normal level of total α-tubulin in the axoneme but had reduced levels of soluble (membrane plus matrix [M+M]) α-tubulin (Figure 7, A and B). For quantification of the PTM levels, we averaged data obtained from three independent preparations of cilia and normalized the signals to the signal of total tubulin. Although there is some variability in the patterns of PTM signals between the experiments, on average, 13BC-KO cilia had increased levels of tubulin PTMs, especially monoglycylation. The average levels of PTMs on axonemes were also mildly elevated except for polyglycylation (Figure 7C). Surprisingly, the tubulin in the soluble fraction of 13BC-KO cilia, while less abundant, contained 2- to 2.5-fold increased levels of K-40 acetylated, polyglycylated, and polyglutamylated isoforms (Figures 7, A, right, and C). Thus kinesin-13 affects the levels of tubulin PTMs, particularly in the soluble compartment of cilia.
Affiliation: Department of Cellular Biology, University of Georgia, Athens, GA 30602;