title: TPX2 is required for postmitotic nuclear assembly in cell-free Xenopus laevis egg extracts.
abstract: Cell division in many metazoa is accompanied by the disassembly of the nuclear envelope and the assembly of the mitotic spindle. These dramatic structural rearrangements are reversed after mitosis, when the mitotic spindle is dismantled and the nuclear envelope reassembles. The targeting protein for XKlp2 (TPX2) plays important roles in mitotic spindle assembly. We report that TPX2 depletion from nuclear assembly extracts prepared from Xenopus laevis eggs results in the formation of nuclei that are only about one fifth the size of control nuclei. TPX2-depleted nuclei assemble nuclear envelopes, nuclear pore complexes, and a lamina, and they perform nuclear-specific functions, including DNA replication. We show that TPX2 interacts with lamina-associated polypeptide 2 (LAP2), a protein known to be required for nuclear assembly in interphase extracts and in vitro. LAP2 localization is disrupted in TPX2-depleted nuclei, suggesting that the interaction between TPX2 and LAP2 is required for postmitotic nuclear reformation.
authors.affiliation: Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706, USA.
authors.forename: Lori L
authors.initials: LL
authors.lastname: O'Brien
authors.forename: Christiane
authors.initials: C
authors.lastname: Wiese
mesh_terms: D000818:Animals; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism*; D002474:Cell-Free System / Q000737:chemistry / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D066298:In Vitro Techniques; D008565:Membrane Proteins / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008938:Mitosis; D009363:Neoplasm Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism*; D010063:Ovum / Q000737:chemistry*; D010750:Phosphoproteins / Q000378:metabolism*; D011485:Protein Binding; D014020:Tissue Extracts / Q000737:chemistry / Q000378:metabolism; D029867:Xenopus Proteins / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D008565:Membrane Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; C486551:TPX2 protein, Xenopus; D014020:Tissue Extracts; D029867:Xenopus Proteins; C093413:lamina-associated polypeptide 2