title: Identification of a novel microtubule-destabilizing motif in CPAP that binds to tubulin heterodimers and inhibits microtubule assembly.
abstract: We have previously identified a new centrosomal protein, centrosomal protein 4.1-associated protein (CPAP), which is associated with the gamma-tubulin complex. Here, we report that CPAP carries a novel microtubule-destabilizing motif that not only inhibits microtubule nucleation from the centrosome but also depolymerizes taxol-stabilized microtubules. Deletion mapping and functional analyses have defined a 112-residue CPAP that is necessary and sufficient for microtubule destabilization. This 112-residue CPAP directly recognizes the plus end of a microtubule and inhibits microtubule nucleation from the centrosome. Biochemical and functional analyses revealed that this 112-residue CPAP also binds to tubulin dimers, resulting in the destabilization of microtubules. Using the tetracycline-controlled system (tet-off), we observed that overexpression of this 112-residue CPAP inhibits cell proliferation and induces apoptosis after G2/M arrest. The possible mechanisms of how this 112-residue motif in CPAP that inhibits microtubule nucleation from the centrosome and disassembles preformed microtubules are discussed.
authors.affiliation: Institute of Biomedical Sciences, Academia Sinica, Taipei 115, Taiwan.
authors.forename: Liang-Yi
authors.initials: LY
authors.lastname: Hung
authors.forename: Hua-Ling
authors.initials: HL
authors.lastname: Chen
authors.forename: Ching-Wen
authors.initials: CW
authors.lastname: Chang
authors.forename: Bor-Ran
authors.initials: BR
authors.lastname: Li
authors.forename: Tang K
authors.initials: TK
authors.lastname: Tang
mesh_terms: D020816:Amino Acid Motifs; D017209:Apoptosis; D002455:Cell Division; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D018385:Centrosome / Q000378:metabolism; D019281:Dimerization; D016195:G2 Phase; D006367:HeLa Cells; D006801:Humans; D008869:Microtubule-Associated Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*
chemical_list: C414735:CENPJ protein, human; D008869:Microtubule-Associated Proteins; D014404:Tubulin; D017239:Paclitaxel