scholarly journals Phosphoinositide-mediated ring anchoring resists perpendicular forces to promote medial cytokinesis

2017 ◽  
Vol 216 (10) ◽  
pp. 3041-3050 ◽  
Author(s):  
Chloe E. Snider ◽  
Alaina H. Willet ◽  
Jun-Song Chen ◽  
Göker Arpağ ◽  
Marija Zanic ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Lipid Composition ◽  
Eukaryotic Cells ◽  
Central Position ◽  
Dependent Manner ◽  
Myosin V ◽  
Contractile Ring ◽  
Phosphatidylinositol 4

Many eukaryotic cells divide by assembling and constricting an actin- and myosin-based contractile ring (CR) that is physically linked to the plasma membrane (PM). In this study, we report that Schizosaccharomyces pombe cells lacking efr3, which encodes a conserved PM scaffold for the phosphatidylinositol-4 kinase Stt4, build CRs that can slide away from the cell middle during anaphase in a myosin V–dependent manner. The Efr3-dependent CR-anchoring mechanism is distinct from previously reported pathways dependent on the Fes/CIP4 homology Bin-Amphiphysin-Rvs167 (F-BAR) protein Cdc15 and paxillin Pxl1. In efr3Δ, the concentrations of several membrane-binding proteins were reduced in the CR and/or on the PM. Our results suggest that proper PM lipid composition is important to stabilize the central position of the CR and resist myosin V–based forces to promote the fidelity of cell division.

scholarly journals A Link between Aurora Kinase and Clp1/Cdc14 Regulation Uncovered by the Identification of a Fission Yeast Borealin-Like Protein

2009 ◽  
Vol 20 (16) ◽  
pp. 3646-3659 ◽  
Author(s):  
K. Adam Bohnert ◽  
Jun-Song Chen ◽  
Dawn M. Clifford ◽  
Craig W. Vander Kooi ◽  
Kathleen L. Gould
Keyword(s):  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Kinase Activity ◽  
Sequence Similarity ◽  
Aurora Kinase ◽  
Genetic Interactions ◽  
Aurora B ◽  
Contractile Ring ◽  
Chromosomal Passenger

The chromosomal passenger complex (CPC) regulates various events in cell division. This complex is composed of a catalytic subunit, Aurora B kinase, and three nonenzymatic subunits, INCENP, Survivin, and Borealin. Together, these four subunits interdependently regulate CPC function, and they are highly conserved among eukaryotes. However, a Borealin homologue has never been characterized in the fission yeast, Schizosaccharomyces pombe . Here, we isolate a previously uncharacterized S. pombe protein through association with the Cdc14 phosphatase homologue, Clp1/Flp1, and identify it as a Borealin-like member of the CPC. Nbl1 (novel Borealin-like 1) physically associates with known CPC components, affects the kinase activity and stability of the S. pombe Aurora B homologue, Ark1, colocalizes with known CPC subunits during mitosis, and shows sequence similarity to human Borealin. Further analysis of the Clp1–Nbl1 interaction indicates that Clp1 requires CPC activity for proper accumulation at the contractile ring (CR). Consistent with this, we describe negative genetic interactions between mutant alleles of CPC and CR components. Thus, this study characterizes a fission yeast Borealin homologue and reveals a previously unrecognized connection between the CPC and the process of cytokinesis in S. pombe .

scholarly journals Copper transport and regulation in Schizosaccharomyces pombe

2013 ◽  
Vol 41 (6) ◽  
pp. 1679-1686 ◽  
Author(s):  
Jude Beaudoin ◽  
Seda Ekici ◽  
Fevzi Daldal ◽  
Samia Ait-Mohand ◽  
Brigitte Guérin ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Plasma Membrane ◽  
Schizosaccharomyces Pombe ◽  
Copper Metabolism ◽  
Eukaryotic Cells ◽  
Stepping Stones ◽  
Copper Transporter ◽  
Fundamental Knowledge ◽  
Membrane Complex ◽  
Related Proteins

The fission yeast Schizosaccharomyces pombe has been successfully used as a model to gain fundamental knowledge in understanding how eukaryotic cells acquire copper during vegetative growth. These studies have revealed the existence of a heteromeric Ctr4–Ctr5 plasma membrane complex that mediates uptake of copper within the cells. Furthermore, additional studies have led to the identification of one of the first vacuolar copper transporters, Ctr6, as well as the copper-responsive Cuf1 transcription factor. Recent investigations have extended the use of S. pombe to elucidate new roles for copper metabolism in meiotic differentiation. For example, these studies have led to the discovery of Mfc1, which turned out to be the first example of a meiosis-specific copper transporter. Whereas copper-dependent transcriptional regulation of the Ctr family members is under the control of Cuf1 during mitosis or meiosis, meiosis-specific copper transporter Mfc1 is regulated by the recently discovered transactivator Mca1. It is foreseeable that identification of novel meiotic copper-related proteins will serve as stepping stones to unravel fundamental aspects of copper homoeostasis.

scholarly journals A novel coordinated function of Myosin II with GOLPH3 controls centralspindlin localization during cytokinesis in Drosophila

2020 ◽  
Vol 133 (21) ◽  
pp. jcs252965
Author(s):  
Stefano Sechi ◽  
Anna Frappaolo ◽  
Angela Karimpour-Ghahnavieh ◽  
Roberta Fraschini ◽  
Maria Grazia Giansanti
Keyword(s):  
Plasma Membrane ◽  
Heavy Chain ◽  
Light Chain ◽  
Animal Cell ◽  
Myosin Ii ◽  
Contractile Ring ◽  
Ring Assembly ◽  
Missense Allele ◽  
Phosphatidylinositol 4 ◽  
Muscle Myosin

ABSTRACTIn animal cell cytokinesis, interaction of non-muscle myosin II (NMII) with F-actin provides the dominant force for pinching the mother cell into two daughters. Here we demonstrate that celibe (cbe) is a missense allele of zipper, which encodes the Drosophila Myosin heavy chain. Mutation of cbe impairs binding of Zipper protein to the regulatory light chain Spaghetti squash (Sqh). In dividing spermatocytes from cbe males, Sqh fails to concentrate at the equatorial cortex, resulting in thin actomyosin rings that are unable to constrict. We show that cbe mutation impairs localization of the phosphatidylinositol 4-phosphate [PI(4)P]-binding protein Golgi phosphoprotein 3 (GOLPH3, also known as Sauron) and maintenance of centralspindlin at the cell equator of telophase cells. Our results further demonstrate that GOLPH3 protein associates with Sqh and directly binds the centralspindlin subunit Pavarotti. We propose that during cytokinesis, the reciprocal dependence between Myosin and PI(4)P–GOLPH3 regulates centralspindlin stabilization at the invaginating plasma membrane and contractile ring assembly.

scholarly journals Analysis of the contribution of phosphoinositides to medial septation in fission yeast highlights the importance of PI(4,5)P2 for medial contractile ring anchoring

2018 ◽  
Vol 29 (18) ◽  
pp. 2148-2155 ◽  
Author(s):  
Chloe E. Snider ◽  
Alaina H. Willet ◽  
HannahSofia T. Brown ◽  
Kathleen L. Gould
Keyword(s):  
Plasma Membrane ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Specific Role ◽  
Elevated Plasma ◽  
Contractile Ring ◽  
Nuclear Position

In Schizosaccharomyces pombe, loss of the plasma membrane PI4-kinase scaffold Efr3 leads to sliding of the cytokinetic ring (CR) away from the cell center during anaphase, implicating phosphoinositides (PIPs) in CR anchoring. However, whether other PIP regulators contribute to CR anchoring has not been investigated. Here we report that mutants of other PIP kinases and their regulators divide with off-center septa, similar to efr3∆. Using new biosensors for S. pombe PIPs, we confirm that these mutants have disrupted PIP composition. We extend a previous finding that a mutant known to decrease PI(3,5)P2 levels indirectly affects CR positioning by increasing vacuole size which disrupts nuclear position at the onset of mitosis. Indeed, we found that other mutants with increased vacuole size also disrupt medial division via this mechanism. Although elevated plasma membrane PI(4,5)P2 levels do not affect medial cytokinesis, mutants with decreased levels display CR sliding events indicating a specific role for PI(4,5)P2 in CR anchoring.

Microfilaments and cytoplasmic microtubules in cell division cycle mutants of Schizosaccharomyces pombe

1980 ◽  
Vol 26 (2) ◽  
pp. 250-254 ◽  
Author(s):  
E. Streiblová ◽  
M. Girbardt
Keyword(s):  
Plasma Membrane ◽  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Cell Division Cycle ◽  
Restrictive Temperature ◽  
Septum Formation ◽  
Cytoplasmic Microtubules

The occurrence of axial cytoplasmic microtubules (25 nm in diameter) and of microfilaments (7 nm in diameter) associated in bundles just below the plasma membrane of the yeast Schizosaccharomyces pombe is described. Both types of cytoplasmic filamentous structures were present in the cell division cycle mutant cdc 12–112 of this fungus incubated for 6 h at the restrictive temperature of 35 °C. Microtubules and microfilaments probably function in septum formation and (or) in the volume-related control of the terminal phenotype of the mutant.

Caveolae: Structure, Function, and Relationship to Disease

2018 ◽  
Vol 34 (1) ◽  
pp. 111-136 ◽  
Author(s):  
Robert G. Parton
Keyword(s):  
Signal Transduction ◽  
Plasma Membrane ◽  
Structure Function ◽  
Lipid Composition ◽  
Mammalian Cells ◽  
Eukaryotic Cells ◽  
Interacting Proteins ◽  
Endocytic Vesicle ◽  
Cellular Functions

The plasma membrane of eukaryotic cells is not a simple sheet of lipids and proteins but is differentiated into subdomains with crucial functions. Caveolae, small pits in the plasma membrane, are the most abundant surface subdomains of many mammalian cells. The cellular functions of caveolae have long remained obscure, but a new molecular understanding of caveola formation has led to insights into their workings. Caveolae are formed by the coordinated action of a number of lipid-interacting proteins to produce a microdomain with a specific structure and lipid composition. Caveolae can bud from the plasma membrane to form an endocytic vesicle or can flatten into the membrane to help cells withstand mechanical stress. The role of caveolae as mechanoprotective and signal transduction elements is reviewed in the context of disease conditions associated with caveola dysfunction.

scholarly journals The PI(4)P phosphatase Sac2 controls insulin granule docking and release

2019 ◽  
Vol 218 (11) ◽  
pp. 3714-3729 ◽  
Author(s):  
Phuoc My Nguyen ◽  
Nikhil R. Gandasi ◽  
Beichen Xie ◽  
Sari Sugahara ◽  
Yingke Xu ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Plasma Membrane ◽  
Insulin Secretion ◽  
Dependent Manner ◽  
Impaired Insulin Secretion ◽  
Insulin Granules ◽  
Impaired Insulin ◽  
Insulin Granule ◽  
Phosphatidylinositol 4

Insulin granule biogenesis involves transport to, and stable docking at, the plasma membrane before priming and fusion. Defects in this pathway result in impaired insulin secretion and are a hallmark of type 2 diabetes. We now show that the phosphatidylinositol 4-phosphate phosphatase Sac2 localizes to insulin granules in a substrate-dependent manner and that loss of Sac2 results in impaired insulin secretion. Sac2 operates upstream of granule docking, since loss of Sac2 prevented granule tethering to the plasma membrane and resulted in both reduced granule density and number of exocytic events. Sac2 levels correlated positively with the number of docked granules and exocytic events in clonal β cells and with insulin secretion in human pancreatic islets, and Sac2 expression was reduced in islets from type 2 diabetic subjects. Taken together, we identified a phosphoinositide switch on the surface on insulin granules that is required for stable granule docking at the plasma membrane and impaired in human type 2 diabetes.

scholarly journals The Forkhead Transcription Factor Fkh2 Regulates the Cell Division Cycle of Schizosaccharomyces pombe

2004 ◽  
Vol 3 (4) ◽  
pp. 944-954 ◽  
Author(s):  
Richard Bulmer ◽  
Aline Pic-Taylor ◽  
Simon K. Whitehall ◽  
Kate A. Martin ◽  
Jonathan B. A. Millar ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Transcription Factor ◽  
Cell Division ◽  
Schizosaccharomyces Pombe ◽  
Regulation Of Gene Expression ◽  
Cell Division Cycle ◽  
Specific Gene ◽  
Dependent Manner ◽  
Forkhead Transcription Factor

ABSTRACT In eukaryotes the regulation of gene expression plays a key role in controlling cell cycle progression. Here, we demonstrate that a forkhead transcription factor, Fkh2, regulates the periodic expression of cdc15 + and spo12 + in the M and G1 phases of the cell division cycle in the fission yeast Schizosaccharomyces pombe. We also show that Fkh2 is important for several cell cycle processes, including cell morphology and cell separation, nuclear structure and migration, and mitotic spindle function. We find that the expression of fkh2 + is itself regulated in a cell cycle-dependent manner in G1 coincident with the expression of cdc18 +, a Cdc10-regulated gene. However, fkh2 + expression is independent of Cdc10 function. Fkh2 was found to be phosphorylated during the cell division cycle, with a timing that suggests that this posttranslational modification is important for cdc15 + and spo12 + expression. Related forkhead proteins regulate G2 and M phase-specific gene expression in the evolutionarily distant Saccharomyces cerevisiae, suggesting that these proteins play conserved roles in regulating cell cycle processes in eukaryotes.

scholarly journals A single-headed fission yeast myosin V transports actin in a tropomyosin-dependent manner

2016 ◽  
Vol 214 (2) ◽  
pp. 167-179 ◽  
Author(s):  
Qing Tang ◽  
Neil Billington ◽  
Elena B. Krementsova ◽  
Carol S. Bookwalter ◽  
Matthew Lord ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Cellular Localization ◽  
Dependent Manner ◽  
Myosin V ◽  
Contractile Ring ◽  
Class V ◽  
Ring Assembly ◽  
Attachment Sites ◽  
And Function

Myo51, a class V myosin in fission yeast, localizes to and assists in the assembly of the contractile ring, a conserved eukaryotic actomyosin structure that facilitates cytokinesis. Rng8 and Rng9 are binding partners that dictate the cellular localization and function of Myo51. Myo51 was expressed in insect cells in the presence or absence of Rng8/9. Surprisingly, electron microscopy of negatively stained images and hydrodynamic measurements showed that Myo51 is single headed, unlike most class V myosins. When Myo51–Rng8/9 was bound to actin-tropomyosin, two attachment sites were observed: the typical ATP-dependent motor domain attachment and a novel ATP-independent binding of the tail mediated by Rng8/9. A modified motility assay showed that this additional binding site anchors Myo51–Rng8/9 so that it can cross-link and slide actin-tropomyosin filaments relative to one another, functions that may explain the role of this motor in contractile ring assembly.

scholarly journals Making the Final Cut — Mechanisms Mediating the Abscission Step of Cytokinesis

2010 ◽  
Vol 10 ◽  
pp. 1424-1434 ◽  
Author(s):  
John A. Schiel ◽  
Rytis Prekeris
Keyword(s):  
Plasma Membrane ◽  
Cell Division ◽  
Cleavage Plane ◽  
Mitotic Cell ◽  
Dense Region ◽  
Contractile Ring ◽  
Physical Separation ◽  
Daughter Cells ◽  
Considerable Controversy ◽  
The Subject

Cytokinesis is the final stage of mitotic cell division that results in a physical separation of two daughter cells. Cytokinesis begins in the early stages of anaphase after the positioning of the cleavage plane and after the chromosomes segregate. This involves the recruitment and assembly of an actomyosin contractile ring, which constricts the plasma membrane and compacts midzone microtubules to form an electron-dense region, termed the midbody, located within an intracellular bridge. The resolution of this intracellular bridge, known as abscission, is the last step in cytokinesis that separates the two daughter cells. While much research has been done to delineate the mechanisms mediating actomyosin ring formation and contraction, the machinery that is responsible for abscission remains largely unclear. Recent work from several laboratories has demonstrated that dramatic changes occur in cytoskeleton and endosome dynamics, and are a prerequisite for abscission. However, the mechanistic details that regulate the final plasma membrane fusion during abscission are only beginning to emerge and are the subject of considerable controversy. Here we review recent studies within this field and discuss the proposed models of cell abscission.

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