title: Hepatoma up-regulated protein is required for chromatin-induced microtubule assembly independently of TPX2.
abstract: The production of RanGTP around chromosomes is crucial for spindle microtubule assembly in mitosis. Previous work has shown that hepatoma up-regulated protein (HURP) is a Ran target, required for microtubule stabilization and spindle organization. Here we report a detailed analysis of HURP function in Xenopus laevis mitotic egg extracts. HURP depletion severely impairs bipolar spindle assembly around chromosomes: the few spindles that do form show a significant decrease in microtubule density at the spindle midzone. HURP depletion does not interfere with microtubule growth from purified centrosomes, but completely abolishes microtubule assembly induced by chromatin beads or RanGTP. Simultaneous depletion of the microtubule destabilizer MCAK with HURP does not rescue the phenotype, demonstrating that the effect of HURP is not to antagonize the destabilization activity of MCAK. Although the phenotype of HURP depletion closely resembles that reported for TPX2 depletion, we find no evidence that TPX2 and HURP physically interact or that they influence each other in their effects on spindle microtubules. Our data indicate that HURP and TPX2 have nonredundant functions essential for chromatin-induced microtubule assembly.
authors.affiliation: European Molecular Biology Laboratory, 69117 Heidelberg, Germany.
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Casanova
authors.forename: Sofia
authors.initials: S
authors.lastname: Rybina
authors.forename: Hideki
authors.initials: H
authors.lastname: Yokoyama
authors.forename: Eric
authors.initials: E
authors.lastname: Karsenti
authors.forename: Iain W
authors.initials: IW
authors.lastname: Mattaj
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism; D002457:Cell Extracts; D016764:Cell Polarity; D018385:Centrosome / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D010063:Ovum / Q000166:cytology; D010750:Phosphoproteins / Q000378:metabolism; D021381:Protein Transport; D008941:Spindle Apparatus / Q000378:metabolism; D014981:Xenopus; D029867:Xenopus Proteins / Q000378:metabolism*; D020931:ran GTP-Binding Protein / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D002457:Cell Extracts; D002843:Chromatin; D008869:Microtubule-Associated Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; C486551:TPX2 protein, Xenopus; D029867:Xenopus Proteins; D020931:ran GTP-Binding Protein
references.citation: Science. 1999 May 21;284(5418):1356-8
references.pmid: 10334990
references.citation: Biochemistry. 1996 Feb 20;35(7):2365-73
references.pmid: 8652578
references.citation: Curr Biol. 1999 May 6;9(9):481-4
references.pmid: 10322113
references.citation: J Cell Biol. 2005 Sep 26;170(7):1057-66
references.pmid: 16172207
references.citation: Methods Cell Biol. 1999;61:385-412
references.pmid: 9891325
references.citation: J Mol Biol. 2007 Feb 2;365(5):1587-95
references.pmid: 17118403
references.citation: J Cell Biol. 2000 Jun 26;149(7):1405-18
references.pmid: 10871281
references.citation: Nat Cell Biol. 2001 Mar;3(3):228-34
references.pmid: 11231571
references.citation: Science. 2002 Mar 29;295(5564):2452-6
references.pmid: 11923538
references.citation: J Cell Sci. 2007 Nov 1;120(Pt 21):3748-61
references.pmid: 17940066
references.citation: Cell. 2001 Jan 12;104(1):83-93
references.pmid: 11163242
references.citation: J Biol Chem. 1997 Aug 1;272(31):19418-24
references.pmid: 9235942
references.citation: Curr Biol. 2006 Apr 18;16(8):743-54
references.pmid: 16631581
references.citation: Proc Natl Acad Sci U S A. 1995 May 9;92(10):4289-93
references.pmid: 7753799
references.citation: Science. 1999 May 21;284(5418):1359-62
references.pmid: 10334991
references.citation: Protein Expr Purif. 2003 Nov;32(1):83-8
references.pmid: 14680943
references.citation: Nat Protoc. 2006;1(5):2305-14
references.pmid: 17406472
references.citation: Curr Biol. 2006 Apr 18;16(8):731-42
references.pmid: 16631580
references.citation: EMBO J. 2003 May 1;22(9):2060-70
references.pmid: 12727873
references.citation: Nature. 2006 Mar 30;440(7084):697-701
references.pmid: 16572176
references.citation: J Cell Biol. 2008 Mar 10;180(5):867-75
references.pmid: 18316407
references.citation: Science. 2005 Aug 26;309(5739):1373-6
references.pmid: 16123300
references.citation: Mol Biol Cell. 2004 Dec;15(12):5318-28
references.pmid: 15385625
references.citation: J Cell Biol. 2006 Jun 19;173(6):879-91
references.pmid: 16769820
references.citation: Nature. 1999 Jul 8;400(6740):178-81
references.pmid: 10408446
references.citation: J Cell Biol. 2004 Sep 27;166(7):949-55
references.pmid: 15452138
references.citation: Nat Cell Biol. 2002 Nov;4(11):871-9
references.pmid: 12389033
references.citation: Mol Biol Cell. 2008 May;19(5):2083-91
references.pmid: 18321990
references.citation: Proc Natl Acad Sci U S A. 1994 Mar 29;91(7):2587-91
references.pmid: 8146159
references.citation: Cell Motil Cytoskeleton. 1987;8(3):238-49
references.pmid: 3690689
references.citation: J Cell Biol. 1989 Oct;109(4 Pt 1):1389-97
references.pmid: 2677018
references.citation: PLoS Biol. 2007 Feb;5(2):e29
references.pmid: 17227146
references.citation: Cell. 1996 Jan 12;84(1):37-47
references.pmid: 8548824
references.citation: Oncogene. 2003 Jan 16;22(2):298-307
references.pmid: 12527899
references.citation: Methods Enzymol. 1991;196:478-85
references.pmid: 2034137
references.citation: Int Rev Cytol. 2008;265:111-58
references.pmid: 18275887