title: Role of DNA topoisomerase IIbeta in neurite outgrowth.
abstract: Failure to establish neuromuscular junctions is a major phenotype of top2beta knockout mice. However, the precise mechanism for this defect is not known. In the current study, we have investigated the role of TopIIbeta in cultured neurons. We showed that the TopII inhibitor ICRF-193 significantly blocked neurite outgrowth and growth cone formation in cultured cerebellar granule neurons (CGNs), dorsal root ganglions (DRGs) and cortical neurons (CNs). In addition, ICRF-193 also blocked neurite outgrowth and growth cone formation of PC12 cells undergoing NGF-induced differentiation. Isolated cortical neurons from top2beta knockout embryos elaborated shorter neurites than did those from their wild type counterparts, confirming the role of TopIIbeta in neurite outgrowth. Together, these results demonstrate a critical role of TopIIbeta in neurite outgrowth in cultured neurons. Furthermore, we demonstrated that neurons derived from top2beta knockout mice failed to form contacts with muscle cells in co-cultures. These results suggest that the defect in establishing neuromuscular junctions in top2beta knockout mice could be due to the lack of TopIIbeta-mediated neurite outgrowth.
authors.affiliation: Department of Biology, MEC-CUNY, 1150 Carroll Street, Brooklyn, NY 11225, USA. alam@mec.cuny.edu
authors.forename: Alam
authors.initials: A
authors.lastname: Nur-E-Kamal
authors.forename: Sally
authors.initials: S
authors.lastname: Meiners
authors.forename: Ijaz
authors.initials: I
authors.lastname: Ahmed
authors.forename: Anna
authors.initials: A
authors.lastname: Azarova
authors.forename: Chao-po
authors.initials: CP
authors.lastname: Lin
authors.forename: Yi Lisa
authors.initials: YL
authors.lastname: Lyu
authors.forename: Leroy F
authors.initials: LF
authors.lastname: Liu
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D002540:Cerebral Cortex / Q000166:cytology; D018920:Coculture Techniques / Q000379:methods; D004250:DNA Topoisomerases, Type II / Q000172:deficiency / Q000502:physiology*; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000502:physiology*; D054659:Diketopiperazines; D004622:Embryo, Mammalian; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005727:Ganglia, Spinal / Q000166:cytology; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000235:genetics; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D032446:Myoblasts / Q000502:physiology; D016501:Neurites / Q000187:drug effects / Q000502:physiology*; D009474:Neurons / Q000166:cytology* / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology; D051381:Rats
chemical_list: D004268:DNA-Binding Proteins; D054659:Diketopiperazines; D004791:Enzyme Inhibitors; D010879:Piperazines; C070899:4,4'-(1,2-dimethyl-1,2-ethanediyl)bis-2,6-piperazinedione; D004250:DNA Topoisomerases, Type II