γ-tubulin 2 nucleates microtubules and is downregulated in mouse early embryogenesisγ-tubulin 2成核微管和小鼠早期胚胎中表达下调.pdfVIP

c-Tubulin 2 Nucleates Microtubules and Is Downregulated in Mouse Early Embryogenesis 1 ´ ˇ ´ 1 1 1 ˇ ´ 1 Stanislav Vinopal , Marketa Cernohorska , Vadym Sulimenko , Tetyana Sulimenko , Vera Vosecka , ´ ˇ 2 ´ ´ 1 ´ 1 Matyas Flemr , Eduarda Draberova , Pavel Draber * 1 Department of Biology of Cytoskeleton, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic, 2 Department of Epigenetic Regulations, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic Abstract c-Tubulin is the key protein for microtubule nucleation. Duplication of the c-tubulin gene occurred several times during evolution, and in mammals c-tubulin genes encode proteins which share ,97% sequence identity. Previous analysis of Tubg1 and Tubg2 knock-out mice has suggested that c-tubulins are not functionally equivalent. Tubg1 knock-out mice died at the blastocyst stage, whereas Tubg2 knock-out mice developed normally and were fertile. It was proposed that c-tubulin 1 represents ubiquitous c-tubulin, while c-tubulin 2 may have some specific functions and cannot substitute for c-tubulin 1 deficiency in blastocysts. The molecular basis of the suggested functional difference between c-tubulins remains unknown. Here we show that exogenous c-tubulin 2 is targeted to centrosomes and interacts with c-tubulin complex proteins 2 and 4. Depletion of c-tubulin 1 by RNAi in U2OS cells causes impaired microtubule nucleation and metaphase arrest. Wild-type phenotype in c-tubulin 1-depleted cells is restored by expression of exogenous mouse or human c-tubu