D-TACC: a novel centrosomal protein required for normal spindle function in the early Drosophila embryo

We identify Drosophila TACC (D-TACC) as a novel protein that is concentrate d at centrosomes and interacts with microtubules. We show that D-TACC is es sential for normal spindle function in the early embryo; if D-TACC function is perturbed by mutation or antibody injection, the microtubules emanating from centrosomes in embryos are short and chromosomes often fail to segreg ate properly. The C-terminal region of D-TACC interacts, possibly indirectl y, with microtubules, and can target a heterologous fusion protein to centr osomes and microtubules in embryos. This C-terminal region is related to th e mammalian transforming, acidic, coiled-coil-containing (TACC) family of p roteins. The function of the TACC proteins is unknown, but the genes encodi ng the known TACC proteins are all associated with genomic regions that are rearranged in certain cancers. We show that at least one of the mammalian TACC proteins appears to be associated with centrosomes and microtubules in human cells. We propose that this conserved C-terminal 'TACC domain' defin es a new family of microtubule-interacting proteins.