title: Type I platelet-activating factor acetylhydrolase catalytic subunits over-expression induces pleiomorphic nuclei and centrosome amplification.
abstract: LIS1, a causative gene product for type I lissencephaly, binds to and regulates the dynein motor and the centrosome. LIS1 also forms a complex with the catalytic subunits alpha1 and alpha2 of type I platelet-activating factor acetylhydrolase [PAF-AH (I)]. However, the cellular function of the catalytic subunits remains unknown. In this study, we showed that over-expression of the catalytic subunits, especially alpha2, in cultured cells induced dramatic phenotypical changes including nuclear shape change, centrosomal amplification and microtubule disorganization. We examined if these effects were due to the catalytic activity and/or binding of alpha2 to LIS1. Substitution of a single amino acid Glu39 of murine alpha1 and alpha2 by Asp (alpha2-E39D) did not affect catalytic activity but completely abolished LIS1 binding. Over-expression of either alpha2-E39D or the catalytically inactive alpha2-S48C revealed that alpha2-E39D, but not alpha2-S48C, lost its ability to induce above-mentioned phenotypic changes. Biochemical analyses showed that LIS1 present in the precipitate fraction of murine brain homogenates could be translocated to the soluble fraction by alpha2, but not by alpha2-E39D. These results suggest that over-expression of the PAF-AH (I) catalytic subunits induces centrosomal amplification and microtubule disorganization by disturbing intracellular localization of LIS1.
authors: Department of Health Chemistry, Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors: Noritaka
authors: N
authors: Yamaguchi
authors: Hiroyuki
authors: H
authors: Koizumi
authors: Junken
authors: J
authors: Aoki
authors: Yumiko
authors: Y
authors: Natori
authors: Kiyotaka
authors: K
authors: Nishikawa
authors: Yasuhiro
authors: Y
authors: Natori
authors: Yasukazu
authors: Y
authors: Takanezawa
authors: Hiroyuki
authors: H
authors: Arai
mesh_terms: D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase / Q000737:chemistry*; D000818:Animals; D001921:Brain / Q000196:embryology / Q000378:metabolism; D016466:CHO Cells; D020134:Catalytic Domain; D002467:Cell Nucleus / Q000378:metabolism*; D018385:Centrosome / Q000378:metabolism / Q000648:ultrastructure*; D006224:Cricetinae; D003412:Cricetulus; D004330:Drosophila; D005786:Gene Expression Regulation; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000737:chemistry; D008954:Models, Biological; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D008869:Microtubule-Associated Proteins; D011994:Recombinant Proteins; D043203:1-Alkyl-2-acetylglycerophosphocholine Esterase; C513190:Pafah1b1 protein, mouse