Leukocyte Locomotion and Accumulation: The Contributions of Cell Polarity and Cell Growth

2015 ◽  
pp. 1-13
Author(s):  
P. C. Wilkinson
Keyword(s):  
Cell Growth ◽  
Cell Polarity

Plant Cell Polarity: Creating Diversity from Inside the Box

2019 ◽  
Vol 35 (1) ◽  
pp. 309-336 ◽  
Author(s):  
Andrew Muroyama ◽  
Dominique Bergmann
Keyword(s):  
Cell Wall ◽  
Cell Growth ◽  
Cell Polarity ◽  
Intracellular Trafficking ◽  
Protein Complexes ◽  
Posttranslational Regulation ◽  
Environmental Signals ◽  
Spatial And Temporal Scales ◽  
Specific Proteins ◽  
Made In

Cell polarity in plants operates across a broad range of spatial and temporal scales to control processes from acute cell growth to systemic hormone distribution. Similar to other eukaryotes, plants generate polarity at both the subcellular and tissue levels, often through polarization of membrane-associated protein complexes. However, likely due to the constraints imposed by the cell wall and their extremely plastic development, plants possess novel polarity molecules and mechanisms highly tuned to environmental inputs. Considerable progress has been made in identifying key plant polarity regulators, but detailed molecular understanding of polarity mechanisms remains incomplete in plants. Here, we emphasize the striking similarities in the conceptual frameworks that generate polarity in both animals and plants. To this end, we highlight how novel, plant-specific proteins engage in common themes of positive feedback, dynamic intracellular trafficking, and posttranslational regulation to establish polarity axes in development. We end with a discussion of how environmental signals control intrinsic polarity to impact postembryonic organogenesis and growth.

scholarly journals Compartmentalized nodes control mitotic entry signaling in fission yeast

2013 ◽  
Vol 24 (12) ◽  
pp. 1872-1881 ◽  
Author(s):  
Lin Deng ◽  
James B. Moseley
Keyword(s):  
Cell Cycle ◽  
Cell Growth ◽  
Fission Yeast ◽  
Cell Polarity ◽  
Cell Cycle Progression ◽  
Interaction Network ◽  
Yeast Cells ◽  
Cell Cortex ◽  
Cycle Progression ◽  
Mitotic Entry

Cell cycle progression is coupled to cell growth, but the mechanisms that generate growth-dependent cell cycle progression remain unclear. Fission yeast cells enter into mitosis at a defined size due to the conserved cell cycle kinases Cdr1 and Cdr2, which localize to a set of cortical nodes in the cell middle. Cdr2 is regulated by the cell polarity kinase Pom1, suggesting that interactions between cell polarity proteins and the Cdr1-Cdr2 module might underlie the coordination of cell growth and division. To identify the molecular connections between Cdr1/2 and cell polarity, we performed a comprehensive pairwise yeast two-hybrid screen. From the resulting interaction network, we found that the protein Skb1 interacted with both Cdr1 and the Cdr1 inhibitory target Wee1. Skb1 inhibited mitotic entry through negative regulation of Cdr1 and localized to both the cytoplasm and a novel set of cortical nodes. Skb1 nodes were distinct structures from Cdr1/2 nodes, and artificial targeting of Skb1 to Cdr1/2 nodes delayed entry into mitosis. We propose that the formation of distinct node structures in the cell cortex controls signaling pathways to link cell growth and division.

scholarly journals Yeast src homology region 3 domain-binding proteins involved in bud formation.

1996 ◽  
Vol 133 (4) ◽  
pp. 865-878 ◽  
Author(s):  
Y Matsui ◽  
R Matsui ◽  
R Akada ◽  
A Toh-e
Keyword(s):  
Cell Growth ◽  
Cell Polarity ◽  
Cell Polarization ◽  
Pleckstrin Homology Domain ◽  
Pleckstrin Homology ◽  
Bud Formation ◽  
Homology Region ◽  
Large Round ◽  
Src Homology ◽  
Two Hybrid

The yeast protein Bem1p, which bears two src homology region 3 (SH3) domains, is involved in cell polarization. A Rho-type GTPase, Rho3p, is involved in the maintenance of cell polarity for bud formation, and the rho3 defect is suppressed by a high dose of BEM1. Mutational analysis revealed that the second SH3 domain from the NH2 terminus (SH3-2) of Bem1p is important for the functions of Bem1p in bud formation and in the suppression of the rho3 defect. Boi2p, which bound to SH3-2 Bem1p, was identified using the two-hybrid system. Boi2p has a proline-rich sequence that is critical for displaying the Boi2p-Bem1p two-hybrid interaction, an SH3 domain in its NH2-terminal half, and a pleckstrin homology domain in its COOH-terminal half. A BOI2 homologue, BOI1, was identified as a gene whose overexpression inhibited cell growth. Cells overexpressing either BOI1 or BOI2 were arrested as large, round, and unbudded cells, indicating that the Boi proteins affect cell polarization. Genetic analysis revealed that BOI1 and BOI2 are functionally redundant and important for cell growth. delta boi1 delta boi2 cells became large round cells or lysed with buds, displaying defects in bud formation and in the maintenance of cell polarity. Analysis using several truncated versions of BOI2 revealed that the COOH-terminal half, which contains the pleckstrin homology domain is essential for the function of Boi2p in cell growth, while the NH2-terminal half is not, and the NH2-terminal half might be required for modulating the function of Bem1p. Overproduction of either Rho3p or the Rho3p-related GTPase Rho4p suppressed the boi defect. These results demonstrate that Rho3p GTPases and Boi proteins function in the maintenance of cell polarity for bud formation.

Vesicle transport during cell growth and in the maintenance of cell polarity

1995 ◽  
Vol 23 (3) ◽  
pp. 530-534 ◽  
Author(s):  
A. H. Futerman ◽  
K. Hirschberg ◽  
I. Meivar-Levy ◽  
E. Rapaport ◽  
A. Schwarz ◽  
...  
Keyword(s):  
Cell Growth ◽  
Cell Polarity ◽  
Vesicle Transport

scholarly journals Cyclical Regulation of the Exocyst and Cell Polarity Determinants for Polarized Cell Growth

2005 ◽  
Vol 16 (3) ◽  
pp. 1500-1512 ◽  
Author(s):  
Allison Zajac ◽  
Xiaoli Sun ◽  
Jian Zhang ◽  
Wei Guo
Keyword(s):  
Cell Growth ◽  
Cell Polarity ◽  
Rab Protein ◽  
Daughter Cells ◽  
Downstream Effector ◽  
Actin Cable ◽  
Exocyst Complex ◽  
Bud Emergence ◽  
Polarized Cell Growth ◽  
Surface Expansion

Polarized exocytosis is important for morphogenesis and cell growth. The exocyst is a multiprotein complex implicated in tethering secretory vesicles at specific sites of the plasma membrane for exocytosis. In the budding yeast, the exocyst is localized to sites of bud emergence or the tips of small daughter cells, where it mediates secretion and cell surface expansion. To understand how exocytosis is spatially controlled, we systematically analyzed the localization of Sec15p, a member of the exocyst complex and downstream effector of the rab protein Sec4p, in various mutants. We found that the polarized localization of Sec15p relies on functional upstream membrane traffic, activated rab protein Sec4p, and its guanine exchange factor Sec2p. The initial targeting of both Sec4p and Sec15p to the bud tip depends on polarized actin cable. However, different recycling mechanisms for rab and Sec15p may account for the different kinetics of polarization for these two proteins. We also found that Sec3p and Sec15p, though both members of the exocyst complex, rely on distinctive targeting mechanisms for their localization. The assembly of the exocyst may integrate various cellular signals to ensure that exocytosis is tightly controlled. Key regulators of cell polarity such as Cdc42p are important for the recruitment of the exocyst to the budding site. Conversely, we found that the proper localization of these cell polarity regulators themselves also requires a functional exocytosis pathway. We further report that Bem1p, a protein essential for the recruitment of signaling molecules for the establishment of cell polarity, interacts with the exocyst complex. We propose that a cyclical regulatory network contributes to the establishment and maintenance of polarized cell growth in yeast.

scholarly journals Cell Polarity and Hyphal Morphogenesis Are Controlled by Multiple Rho-Protein Modules in the Filamentous Ascomycete Ashbya gossypii

Genetics ◽  
2001 ◽  
Vol 157 (2) ◽  
pp. 601-610
Author(s):  
J Wendland ◽  
P Philippsen
Keyword(s):  
Cell Growth ◽  
Filamentous Fungi ◽  
Cell Polarity ◽  
Hyphal Growth ◽  
Ashbya Gossypii ◽  
Rho Proteins ◽  
Filamentous Ascomycete ◽  
Polarized Cell Growth ◽  
Rho Protein ◽  
Protein Modules

Abstract Polarized cell growth requires a polarized organization of the actin cytoskeleton. Small GTP-binding proteins of the Rho-family have been shown to be involved in the regulation of actin polarization as well as other processes. Hyphal growth in filamentous fungi represents an ideal model to investigate mechanisms involved in generating cell polarity and establishing polarized cell growth. Since a potential role of Rho-proteins has not been studied so far in filamentous fungi we isolated and characterized the Ashbya gossypii homologs of the Saccharomyces cerevisiae CDC42, CDC24, RHO1, and RHO3 genes. The AgCDC42 and AgCDC24 genes can both complement conditional mutations in the S. cerevisiae CDC42 and CDC24 genes and both proteins are required for the establishment of actin polarization in A. gossypii germ cells. Agrho1 mutants show a cell lysis phenotype. Null mutant strains of Agrho3 show periodic swelling of hyphal tips that is overcome by repolarization and polar hyphal growth in a manner resembling the germination pattern of spores. Thus different Rho-protein modules are required for distinct steps during polarized hyphal growth of A. gossypii.

scholarly journals The concerted actions of Tip1/CLIP-170, Klp5/Kinesin-8, and Alp14/XMAP215 regulate microtubule catastrophe at the cell end

2019 ◽  
Vol 11 (11) ◽  
pp. 956-966 ◽  
Author(s):  
Xiaojia Niu ◽  
Fan Zheng ◽  
Chuanhai Fu
Keyword(s):  
Cell Growth ◽  
Schizosaccharomyces Pombe ◽  
Fission Yeast ◽  
Cell Polarity ◽  
Residence Time ◽  
Dependent Manner ◽  
Spatial Regulation ◽  
Live Cell Microscopy ◽  
Stabilizing Factors ◽  
Cell Microscopy

Abstract Spatial regulation of microtubule catastrophe is important for controlling microtubule length and consequently contributes to the proper establishment of cell polarity and cell growth. The +TIP proteins including Tip1/CLIP-170, Klp5/Kinesin-8, and Alp14/XMAP215 reside at microtubule plus ends to regulate microtubule dynamics. In the fission yeast Schizosaccharomyces pombe, Tip1 and Alp14 serve as microtubule-stabilizing factors, while Klp5 functions oppositely as a catastrophe-promoting factor. Despite that Tip1 has been shown to play a key role in restricting microtubule catastrophe to the cell end, how Tip1 fulfills the role remains to be determined. Employing live-cell microscopy, we showed that the absence of Tip1 impairs the localization of both Klp5 and Alp14 at microtubule plus ends, but the absence of Klp5 prolongs the residence time of Tip1 at microtubule plus ends. We further revealed that Klp5 accumulates behind Tip1 at microtubule plus ends in a Tip1-dependent manner. In addition, artificially tethering Klp5 to microtubule plus ends promotes premature microtubule catastrophe, while tethering Alp14 to microtubule plus ends in the cells lacking Tip1 rescues the phenotype of short microtubules. These findings establish that Tip1 restricts microtubule catastrophe to the cell end likely by spatially restricting the microtubule catastrophe activity of Klp5 and stabilizing Alp14 at microtubule plus ends. Thus, the work demonstrates the orchestration of Tip1, Alp14, and Klp5 in ensuring microtubule catastrophe at the cell end.

scholarly journals Disruption of PKB signaling restores polarity to cells lacking tumor suppressor PTEN

2011 ◽  
Vol 22 (4) ◽  
pp. 437-447 ◽  
Author(s):  
Ming Tang ◽  
Miho Iijima ◽  
Yoichiro Kamimura ◽  
Lingfeng Chen ◽  
Yu Long ◽  
...  
Keyword(s):  
Cell Growth ◽  
Tumor Suppressor ◽  
Cell Polarity ◽  
Binding Proteins ◽  
Large Fraction ◽  
Normal Behavior ◽  
A Subunit

By limiting phosphotidylinositol 3,4,5-triphosphate (PIP3) levels, tumor suppressor PTEN not only controls cell growth but also maintains cell polarity required for cytokinesis and chemotaxis. To identify the critical targets of PIP3 that link it to the cytoskeleton, we deleted secondary genes to reverse the deficiencies of pten- cells in Dictyostelium. The polarity defects in pten- cells correlate with elevated phosphorylations of PKB substrates. Deletion of AKT orthologue, PkbA, or a subunit of its activator TORC2, reduced the phosphorylations and suppressed the cytokinesis and chemotaxis defects in pten- cells. In these double mutants, the excessive PIP3 levels and, presumably, activation of other PIP3-binding proteins had little or no effect on the cytoskeleton. In bands with increased phosphorylation in pten- cells, we found PKB substrates, PI5K, GefS, GacG, and PakA. Disruption of PakA in pten- cells restored a large fraction of the cells to normal behavior. Consistently, expression of phosphomimetic PakA in pten- cells exacerbated the defects but nonphosphorylatable PakA had no effect. Thus, among many putative PTEN- and PIP3-dependent events, phosphorylation of PKB substrates is the key downstream regulator of cell polarity.

scholarly journals Structure of the 14-3-3ζ–LKB1 fusion protein provides insight into a novel ligand-binding mode of 14-3-3

2015 ◽  
Vol 71 (9) ◽  
pp. 1114-1119 ◽  
Author(s):  
Sheng Ding ◽  
Ruiqing Zhou ◽  
Yaqin Zhu
Keyword(s):  
Crystal Structure ◽  
Energy Metabolism ◽  
Cell Growth ◽  
Fusion Protein ◽  
Ligand Binding ◽  
Cell Polarity ◽  
Binding Mode ◽  
Cellular Processes ◽  
Potential Binding ◽  
Insight Into

The 14-3-3 proteins are a family of highly conserved proteins that play key roles in many cellular processes. The tumour suppressor LKB1 regulates cell polarity, cell growth and energy metabolism. 14-3-3 proteins bind to LKB1 and suppress its functions. Previously, preliminary crystallographic data for the 14-3-3ζ–LKB1 fusion protein have been reported. Here, the crystal structure of this fusion protein was solved and a novel potential binding mode of 14-3-3 to its ligands was found.

scholarly journals Activation of polarized cell growth by inhibition of cell polarity

2018 ◽  
Author(s):  
Marco Geymonat ◽  
Anatole Chessel ◽  
James Dodgson ◽  
Hannah Punter ◽  
Felix Horns ◽  
...  
Keyword(s):  
Cell Growth ◽  
Fission Yeast ◽  
Cell Polarity ◽  
Rho Gtpase ◽  
Dependent Manner ◽  
Polarized Cell Growth ◽  
And Control ◽  
Polarity Factor ◽  
Pak Kinase

AbstractA key feature of cells is the capacity to activate new functional polarized domains contemporaneously to pre-existing ones. How cells accomplish this is not clear. Here, we show that in fission yeast inhibition of cell polarity at pre-existing domains of polarized cell growth is required to activate new growth. This inhibition is mediated by the ERM-related polarity factor Tea3, which antagonizes the activation of the Rho-GTPase Cdc42 by its co-factor Scd2. We demonstrate that Tea3 acts in a phosphorylation-dependent manner controlled by the PAK kinase Shk1 and that, like Scd2, Tea3 is direct substrate of Shk1. Importantly, we show that Tea3 and Scd2 compete for their binding to Shk1, indicating that their biochemical competition for Shk1 underpins their antagonistic roles in controlling polarity. Thus, by preventing pre-existing growth domains from becoming overpowering, Tea3 allows cells to redistribute their polarity-activating machinery to prospective sites and control their timing of activation.

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