scholarly journals A novel interplay between GEFs orchestrates Cdc42 activity during cell polarity and cytokinesis

2018 ◽  
Author(s):  
Brian S. Hercyk ◽  
Julie T. Rich-Robinson ◽  
Ahmad S. Mitoubsi ◽  
Marcus A. Harrell ◽  
Maitreyi E. Das
Keyword(s):  
Fission Yeast ◽  
Cell Polarity ◽  
Cell Separation ◽  
Cell Shape ◽  
Functional Sites ◽  
Cellular Processes ◽  
Division Site ◽  
Summary Statement ◽  
Fine Tune ◽  
Do So

ABSTRACTCdc42, a conserved regulator of cell polarity, is activated by two GEFs, Gef1 and Scd1, in fission yeast. Whilegef1andscd1mutants exhibit distinct phenotypes, how they do so is unclear given that they activate the same GTPase. Using the GEF localization pattern during cytokinesis as a paradigm, we report a novel interplay between Gef1 and Scd1 that spatially modulates Cdc42. We find that Gef1 promotes Scd1 localization to the division site during cytokinesis and to the new end during polarized growth through the recruitment of the scaffold Scd2 via a Cdc42 feedforward pathway. Gef1-mediated Scd1 recruitment at the new end enables the transition from monopolar to bipolar growth. Reciprocally, Scd1 restricts Gef1 localization to prevent ectopic Cdc42 activation during cytokinesis to promote cell separation and during interphase to maintain cell shape. Our findings reveal an elegant regulatory pattern in which Gef1 establishes new sites of Scd1-mediated Cdc42 activity, while Scd1 restricts Gef1 to functional sites. We propose that crosstalk between GEFs is a conserved mechanism that orchestrates Cdc42 activation during complex cellular processes.Summary StatementCdc42 GEFs Gef1 and Scd1 crosstalk to fine-tune Cdc42 activity. This crosstalk promotes bipolar growth and maintains cell shape in fission yeast.

Microtubule Architectural Dynamics Determine Cell Shape and Cell Division Site in Fission Yeast

2004 ◽  
Vol 10 (S02) ◽  
pp. 162-163
Author(s):  
Isabelle Loiodice ◽  
Marcel E. Janson ◽  
Jamye Staub ◽  
Thanuja Gangi-Setty ◽  
Nam P. Nguyen ◽  
...  
Keyword(s):  
Cell Division ◽  
Fission Yeast ◽  
Cell Shape ◽  
Division Site

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

scholarly journals Physical Mechanisms Redirecting Cell Polarity and Cell Shape in Fission Yeast

2008 ◽  
Vol 18 (22) ◽  
pp. 1748-1753 ◽  
Author(s):  
Courtney R. Terenna ◽  
Tatyana Makushok ◽  
Guilhem Velve-Casquillas ◽  
Damien Baigl ◽  
Yong Chen ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Cell Polarity ◽  
Cell Shape ◽  
Physical Mechanisms

scholarly journals Cdc42 promotes Bgs1 recruitment for septum synthesis and glucanase localization for cell separation during cytokinesis in fission yeast

2019 ◽  
Author(s):  
Udo N. Onwubiko ◽  
Julie Robinson ◽  
Rose Albu Mustaf ◽  
Maitreyi E. Das
Keyword(s):  
Fission Yeast ◽  
Membrane Trafficking ◽  
Cell Separation ◽  
Nucleotide Exchange ◽  
Timely Initiation ◽  
Division Site ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Primary Septum ◽  
Ring Constriction

AbstractCytokinesis in fission yeast involves actomyosin ring constriction concurrent to septum synthesis followed by septum digestion resulting in cell separation. A recent report indicates that endocytosis is required for septum synthesis and cell separation. The conserved GTPase Cdc42 is required for membrane trafficking and promotes endocytosis. Cdc42 is activated by Guanine nucleotide exchange factors (GEFs). Cdc42 GEFs have been shown to promote timely initiation of septum synthesis and proper septum morphology. Here we show that Cdc42 promotes the recruitment of the major primary septum synthesizing enzyme Bgs1 and consequent ring constriction. Cdc42 is also required for proper localization of the septum digesting glucanases at the division site. Thus, Cdc42 is required to promote multiple steps during cytokinesis.

scholarly journals Profilin-mediated Competition between Capping Protein and Formin Cdc12p during Cytokinesis in Fission Yeast

2005 ◽  
Vol 16 (5) ◽  
pp. 2313-2324 ◽  
Author(s):  
David R. Kovar ◽  
Jian-Qiu Wu ◽  
Thomas D. Pollard
Keyword(s):  
Fission Yeast ◽  
Actin Filament ◽  
Actin Filaments ◽  
Cell Separation ◽  
The Other ◽  
Temperature Sensitive ◽  
Contractile Ring ◽  
Capping Protein ◽  
Division Site ◽  
Ring Constriction

Fission yeast capping protein SpCP is a heterodimer of two subunits (Acp1p and Acp2p) that binds actin filament barbed ends. Neither acp1 nor acp2 is required for viability, but cells lacking either or both subunits have cytokinesis defects under stressful conditions, including elevated temperature, osmotic stress, or in combination with numerous mild mutations in genes important for cytokinesis. Defects arise as the contractile ring constricts and disassembles, resulting in delays in cell separation. Genetic and biochemical interactions show that the cytokinesis formin Cdc12p competes with capping protein for actin filament barbed ends in cells. Deletion of acp2 partly suppresses cytokinesis defects in temperature-sensitive cdc12-112 cells and mild overexpression of capping protein kills cdc12-112 cells. Biochemically, profilin has opposite effects on filaments capped with Cdc12p and capping protein. Profilin depolymerizes actin filaments capped by capping protein but allows filaments capped by Cdc12p to grow at their barbed ends. Once associated with a barbed end, either Cdc12p or capping protein prevents the other from influencing polymerization at that end. Given that capping protein arrives at the division site 20 min later than Cdc12p, capping protein may slowly replace Cdc12p on filament barbed ends in preparation for filament disassembly during ring constriction.

scholarly journals Fission yeast Pak1 phosphorylates anillin-like Mid1 for spatial control of cytokinesis

2019 ◽  
Author(s):  
Joseph O. Magliozzi ◽  
Jack Sears ◽  
Lauren Cressey ◽  
Marielle Brady ◽  
Hannah E. Opalko ◽  
...  
Keyword(s):  
Cell Division ◽  
Fission Yeast ◽  
Cell Polarity ◽  
Genetic Interactions ◽  
Polarized Growth ◽  
Signaling Mechanism ◽  
Spatial Control ◽  
Division Site ◽  
N Terminus ◽  
A Cell

AbstractProtein kinases direct polarized growth by regulating the cytoskeleton in time and space, and could play similar roles in cell division. We found that the Cdc42-activated polarity kinase Pak1 colocalizes with the assembling contractile actomyosin ring (CAR) and remains at the division site during septation. Mutations in pak1 led to defects in CAR assembly and genetic interactions with cytokinesis mutants. Through a phosphoproteomic screen, we identified novel Pak1 substrates that function in polarized growth and cytokinesis. For cytokinesis, we found that Pak1 regulates the localization of its substrates Mid1 and Cdc15 to the CAR. Mechanistically, Pak1 phosphorylates the Mid1 N-terminus to promote its association with cortical nodes that act as CAR precursors. Defects in Pak1-Mid1 signaling lead to misplaced and defective division planes, but these phenotypes can be rescued by synthetic tethering of Mid1 to cortical nodes. Our work defines a new signaling mechanism driven by a cell polarity kinase that promotes CAR assembly in the correct time and place.SummaryMagliozzi et al. show that fission yeast cell polarity kinase Pak1 regulates cytokinesis. Through a phosphoproteomic screen and subsequent mutant analysis, their work uncovers direct targets and mechanisms for Pak1 activity during cell division.

scholarly journals An anillin homologue, Mid2p, acts during fission yeast cytokinesis to organize the septin ring and promote cell separation

2003 ◽  
Vol 160 (7) ◽  
pp. 1093-1103 ◽  
Author(s):  
Joseph J. Tasto ◽  
Jennifer L. Morrell ◽  
Kathleen L. Gould
Keyword(s):  
Cell Cycle ◽  
Cell Division ◽  
Fission Yeast ◽  
Cell Separation ◽  
Cell Cycle Progression ◽  
Dependent Manner ◽  
Septin Ring ◽  
Protein Levels ◽  
Division Site ◽  
Cell Biol

Anillin is a conserved protein required for cell division (Field, C.M., and B.M. Alberts. 1995. J. Cell Biol. 131:165–178; Oegema, K., M.S. Savoian, T.J. Mitchison, and C.M. Field. 2000. J. Cell Biol. 150:539–552). One fission yeast homologue of anillin, Mid1p, is necessary for the proper placement of the division site within the cell (Chang, F., A. Woollard, and P. Nurse. 1996. J. Cell Sci. 109(Pt 1):131–142; Sohrmann, M., C. Fankhauser, C. Brodbeck, and V. Simanis. 1996. Genes Dev. 10:2707–2719). Here, we identify and characterize a second fission yeast anillin homologue, Mid2p, which is not orthologous with Mid1p. Mid2p localizes as a single ring in the middle of the cell after anaphase in a septin- and actin-dependent manner and splits into two rings during septation. Mid2p colocalizes with septins, and mid2Δ cells display disorganized, diffuse septin rings and a cell separation defect similar to septin deletion strains. mid2 gene expression and protein levels fluctuate during the cell cycle in a sep1- and Skp1/Cdc53/F-box (SCF)–dependent manner, respectively, implying that Mid2p activity must be carefully regulated. Overproduction of Mid2p depolarizes cell growth and affects the organization of both the septin and actin cytoskeletons. In the presence of a nondegradable Mid2p fragment, the septin ring is stabilized and cell cycle progression is delayed. These results suggest that Mid2p influences septin ring organization at the site of cell division and its turnover might normally be required to permit septin ring disassembly.

scholarly journals Forces that shape fission yeast cells

2017 ◽  
Vol 28 (14) ◽  
pp. 1819-1824 ◽  
Author(s):  
Fred Chang
Keyword(s):  
Fission Yeast ◽  
Cell Biology ◽  
Cell Shape ◽  
Turgor Pressure ◽  
Cell Types ◽  
Yeast Cells ◽  
Animal Cells ◽  
Cellular Mechanics ◽  
Cellular Processes ◽  
Micrometer Scale

One of the major challenges of modern cell biology is to understand how cells are assembled from nanoscale components into micrometer-scale entities with a specific size and shape. Here I describe how our quest to understand the morphogenesis of the fission yeast Schizosaccharomyces pombe drove us to investigate cellular mechanics. These studies build on the view that cell shape arises from the physical properties of an elastic cell wall inflated by internal turgor pressure. Consideration of cellular mechanics provides new insights into not only mechanisms responsible for cell-shape determination and growth, but also cellular processes such as cytokinesis and endocytosis. Studies in yeast can help to illuminate approaches and mechanisms to study the mechanobiology of the cell surface in other cell types, including animal cells.

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