title: Regulation of exit from mitosis in multinucleate Ashbya gossypii cells relies on a minimal network of genes.
abstract: In Saccharomyces cerevisiae, mitosis is coupled to cell division by the action of the Cdc fourteen early anaphase release (FEAR) and mitotic exit network (MEN) regulatory networks, which mediate exit from mitosis by activation of the phosphatase Cdc14. The closely related filamentous ascomycete Ashbya gossypii provides a unique cellular setting to study the evolution of these networks. Within its multinucleate hyphae, nuclei are free to divide without the spatial and temporal constraints described for budding yeast. To investigate how this highly conserved system has adapted to these circumstances, we constructed a series of mutants lacking homologues of core components of MEN and FEAR and monitored phenomena such as progression through mitosis and Cdc14 activation. MEN homologues in A. gossypii were shown to have diverged from their anticipated role in Cdc14 release and exit from mitosis. We observed defects in septation, as well as a partial metaphase arrest, in Agtem1Δ, Agcdc15Δ, Agdbf2/dbf20Δ, and Agmob1Δ. A. gossypii homologues of the FEAR network, on the other hand, have a conserved and more pronounced role in regulation of the M/G1 transition. Agcdc55Δ mutants are unable to sequester AgCdc14 throughout interphase. We propose a reduced model of the networks described in yeast, with a low degree of functional redundancy, convenient for further investigations into these networks.
authors: Department of Molecular Microbiology, Biozentrum, University of Basel, 4056 Basel, Switzerland.
authors: Mark R
authors: MR
authors: Finlayson
authors: A Katrin
authors: AK
authors: Helfer-Hungerbühler
authors: Peter
authors: P
authors: Philippsen
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D020090:Chromosome Segregation; D055169:Eremothecium / Q000166:cytology / Q000235:genetics*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D055786:Gene Knockout Techniques; D049452:Green Fluorescent Proteins / Q000378:metabolism; D025301:Hyphae / Q000166:cytology / Q000235:genetics*; D008938:Mitosis / Q000235:genetics*; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D059008:Time-Lapse Imaging
chemical_list: D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D010749:Phosphoprotein Phosphatases