title: GTPase domain driven dimerization of SEPT7 is dispensable for the critical role of septins in fibroblast cytokinesis.
abstract: Septin 7 (SEPT7) has been described to be essential for successful completion of cytokinesis in mouse fibroblasts, and Sept7-deficiency in fibroblasts constitutively results in multinucleated cells which stop proliferation. Using Sept7(flox/flox)fibroblasts we generated a cellular system, where the cytokinetic defects of Cre-mediated deletion of the Sept7 gene can be rescued by ectopically expressed doxycycline-inducible wild type SEPT7. Using this system, we analyzed the ability of SEPT7-mutants with alterations in their GTPase domain-dependent dimerization to prevent multinucleation and rescue proliferation. Although biochemical analysis of the mutants demonstrates differences in homo- and/or hetero-polymerization, in GTP-binding and/or GTPase activities, all analyzed mutants were able to rescue the cytokinesis phenotype of Sept7(flox/flox)fibroblasts associated with Cre-mediated deletion of endogenous Sept7. These findings indicate that the ability of septins to assemble into well-defined SEPT7-dimerization dependent native filaments is dispensable for cytokinesis in fibroblasts and opens the way to search for other mechanisms of the involvement of SEPT7 in cytokinesis.
authors.affiliation: Institute of Physiological Chemistry, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Megha
authors.initials: M
authors.lastname: Abbey
authors.affiliation: Institute of Physiological Chemistry, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Cosima
authors.initials: C
authors.lastname: Hakim
authors.affiliation: Institute of Biophysical Chemistry, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Roopsee
authors.initials: R
authors.lastname: Anand
authors.affiliation: Institute of Physiological Chemistry, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Juri
authors.initials: J
authors.lastname: Lafera
authors.affiliation: Institute of Experimental Hematology, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Axel
authors.initials: A
authors.lastname: Schambach
authors.affiliation: Institute of Molecular Biology, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Kispert
authors.affiliation: Institute of Biophysical Chemistry, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Manuel H
authors.initials: MH
authors.lastname: Taft
authors.affiliation: Institute of Pharmacology, Hannover Medical School, Hannover- 30625, Germany.|Research Core Unit Metabolomics, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Volkhard
authors.initials: V
authors.lastname: Kaever
authors.affiliation: Institute of Physiological Chemistry, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Alexey
authors.initials: A
authors.lastname: Kotlyarov
authors.affiliation: Institute of Physiological Chemistry, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Gaestel
authors.affiliation: Institute of Physiological Chemistry, Hannover Medical School, Hannover- 30625, Germany.
authors.forename: Manoj B
authors.initials: MB
authors.lastname: Menon
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D048749:Cytokinesis; D005347:Fibroblasts / Q000378:metabolism*; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D055786:Gene Knockout Techniques; D006868:Hydrolysis; D051379:Mice; D008958:Models, Molecular; D009154:Mutation; D009711:Nucleotides / Q000378:metabolism; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs / Q000235:genetics; D055503:Protein Multimerization; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D058112:Septins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D009711:Nucleotides; D011993:Recombinant Fusion Proteins; D020558:GTP Phosphohydrolases; C512895:Sept7 protein, mouse; D058112:Septins; C574402:septin 9, mouse
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