title: A link between mitotic entry and membrane growth suggests a novel model for cell size control.
abstract: Addition of new membrane to the cell surface by membrane trafficking is necessary for cell growth. In this paper, we report that blocking membrane traffic causes a mitotic checkpoint arrest via Wee1-dependent inhibitory phosphorylation of Cdk1. Checkpoint signals are relayed by the Rho1 GTPase, protein kinase C (Pkc1), and a specific form of protein phosphatase 2A (PP2A(Cdc55)). Signaling via this pathway is dependent on membrane traffic and appears to increase gradually during polar bud growth. We hypothesize that delivery of vesicles to the site of bud growth generates a signal that is proportional to the extent of polarized membrane growth and that the strength of the signal is read by downstream components to determine when sufficient growth has occurred for initiation of mitosis. Growth-dependent signaling could explain how membrane growth is integrated with cell cycle progression. It could also control both cell size and morphogenesis, thereby reconciling divergent models for mitotic checkpoint function.
authors.affiliation: Department of Molecular, Cell, and Developmental Biology, University of California, Santa Cruz, Santa Cruz, CA 95064, USA.
authors.forename: Steph D
authors.initials: SD
authors.lastname: Anastasia
authors.forename: Duy Linh
authors.initials: DL
authors.lastname: Nguyen
authors.forename: Vu
authors.initials: V
authors.lastname: Thai
authors.forename: Melissa
authors.initials: M
authors.lastname: Meloy
authors.forename: Tracy
authors.initials: T
authors.lastname: MacDonough
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Kellogg
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000096:biosynthesis / Q000378:metabolism; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism*; D048429:Cell Size; D008938:Mitosis; D008954:Models, Biological; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000378:metabolism*; D015398:Signal Transduction; D020666:ras-GRF1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C542351:CDC25 protein, S cerevisiae; D018797:Cell Cycle Proteins; D029701:Saccharomyces cerevisiae Proteins; C101740:ZDS1 protein, S cerevisiae; C101741:ZDS2 protein, S cerevisiae; D020666:ras-GRF1; C099685:SWE1 protein, S cerevisiae; D011505:Protein-Tyrosine Kinases; C490702:PKC1 protein, S cerevisiae; D011493:Protein Kinase C; D017027:Protein Tyrosine Phosphatases