Cell polarity and tissue patterning in plants

Development ◽  
1991 ◽  
Vol 113 (Supplement_1) ◽  
pp. 83-93 ◽  
Author(s):  
Tsvi Sachs
Keyword(s):  
Cell Polarity ◽  
Cell Shape ◽  
Auxin Transport ◽  
Developmental Stages ◽  
Important Determinant ◽  
Genetic System ◽  
Cell Patterning ◽  
Cell Polarization ◽  
Sources And Sinks ◽  
Tissue Patterning

Cell polarization is the specialization of developmental events along one orientation or one direction. Such polarization must be an early, essential stage of tissue patterning. The specification of orientation could not occur only at the level of the genetic system and it must express a coordination of events in many cells. There is a positive feedback relation between cell polarization and the transport of the known hormone auxin: polarity determines oriented auxin transport while transport itself induces both new and continued polarization. Since cell polarization increases gradually, this feedback leads to the canalization of transport – and of the associated cell differentiation – along defined strands of specialized cells. Recent work has shown that the same canalized flow can also be an important determinant of cell shape. In primordial, embryonic regions cell growth is oriented along the flow of auxin from the shoot towards the root. In later developmental stages the cells respond to the same flow by growing in girth, presumably adjusting the capacity of the tissues to the flow of signals. Finally, disrupted flow near wounds results in the development of relatively unorganized callus. Continued callus development appears to require the participation of the cells, as sources and sinks of auxin and other signals. The overall picture to emerge suggests that cell patterning can result from competition between cells acting as preferred channels, sources and sinks for developmental signals.

scholarly journals Cdc42 Is Not Essential for Filopodium Formation, Directed Migration, Cell Polarization, and Mitosis in Fibroblastoid Cells

2005 ◽  
Vol 16 (10) ◽  
pp. 4473-4484 ◽  
Author(s):  
Aleksandra Czuchra ◽  
Xunwei Wu ◽  
Hannelore Meyer ◽  
Jolanda van Hengel ◽  
Timm Schroeder ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Cell Shape ◽  
Cell Polarization ◽  
Small Gtpase ◽  
Dominant Negative ◽  
Directed Migration ◽  
Membrane Blebbing ◽  
Directed Cell Migration ◽  
Rho Family ◽  
Filopodium Formation

Cdc42 is a small GTPase involved in the regulation of the cytoskeleton and cell polarity. To test whether Cdc42 has an essential role in the formation of filopodia or directed cell migration, we generated Cdc42-deficient fibroblastoid cells by conditional gene inactivation. We report here that loss of Cdc42 did not affect filopodium or lamellipodium formation and had no significant influence on the speed of directed migration nor on mitosis. Cdc42-deficient cells displayed a more elongated cell shape and had a reduced area. Furthermore, directionality during migration and reorientation of the Golgi apparatus into the direction of migration was decreased. However, expression of dominant negative Cdc42 in Cdc42-null cells resulted in strongly reduced directed migration, severely reduced single cell directionality, and complete loss of Golgi polarization and of directionality of protrusion formation toward the wound, as well as membrane blebbing. Thus, our data show that besides Cdc42 additional GTPases of the Rho-family, which share GEFs with Cdc42, are involved in the establishment and maintenance of cell polarity during directed migration.

scholarly journals Coordination of Tissue Cell Polarity by Auxin Transport and Signaling

2019 ◽  
Author(s):  
Carla Verna ◽  
Sree Janani Ravichandran ◽  
Megan G. Sawchuk ◽  
Nguyen Manh Linh ◽  
Enrico Scarpella
Keyword(s):  
Cell Polarity ◽  
Auxin Transport ◽  
Molecular Genetic Analysis ◽  
Cell Polarization ◽  
Tissue Cell ◽  
Auxin Signaling ◽  
Plant Signaling ◽  
Chemical Induction ◽  
Vein Formation ◽  
Vein Patterning

AbstractCoordination of polarity between cells in tissues is key to multicellular organism development. In animals, coordination of this tissue cell polarity often requires direct cell-cell interactions and cell movements, which are precluded in plants by a wall that separates cells and holds them in place; yet plants coordinate the polarity of hundreds of cells during the formation of the veins in their leaves. Overwhelming experimental evidence suggests that the plant signaling molecule auxin coordinates tissue cell polarity to induce vein formation, but how auxin does so is unclear. The prevailing hypothesis proposes that GNOM, a regulator of vesicle formation during protein trafficking, positions auxin transporters of the PIN-FORMED family to the correct side of the plasma membrane. The resulting cell-to-cell, polar transport of auxin would coordinate tissue cell polarity and would induce vein formation. Here we tested this hypothesis by means of a combination of cellular imaging, molecular genetic analysis, and chemical induction and inhibition. Contrary to predictions of the hypothesis, we find that auxin-induced vein formation occurs in the absence of PIN-FORMED proteins or any known intercellular auxin transporter, that the residual auxin-transport-independent vein-patterning activity relies on auxin signaling, and that a GNOM-dependent signal that coordinates tissue cell polarity to induce vein formation acts upstream of both auxin transport and signaling. Our results reveal synergism between auxin transport and signaling, and their unsuspected control by GNOM, in the coordination of tissue cell polarity during vein patterning, one of the most spectacular and informative expressions of tissue cell polarization in plants.

scholarly journals Coordination of tissue cell polarity by auxin transport and signaling

eLife ◽  
2019 ◽  
Vol 8 ◽  
Author(s):  
Carla Verna ◽  
Sree Janani Ravichandran ◽  
Megan G Sawchuk ◽  
Nguyen Manh Linh ◽  
Enrico Scarpella
Keyword(s):  
Cell Polarity ◽  
Membrane Trafficking ◽  
Auxin Transport ◽  
Cell Polarization ◽  
Tissue Cell ◽  
Auxin Signaling ◽  
Vein Formation ◽  
Dependent Signal ◽  
Vein Patterning ◽  
Auxin Transporter

Plants coordinate the polarity of hundreds of cells during vein formation, but how they do so is unclear. The prevailing hypothesis proposes that GNOM, a regulator of membrane trafficking, positions PIN-FORMED auxin transporters to the correct side of the plasma membrane; the resulting cell-to-cell, polar transport of auxin would coordinate tissue cell polarity and induce vein formation. Contrary to predictions of the hypothesis, we find that vein formation occurs in the absence of PIN-FORMED or any other intercellular auxin-transporter; that the residual auxin-transport-independent vein-patterning activity relies on auxin signaling; and that a GNOM-dependent signal acts upstream of both auxin transport and signaling to coordinate tissue cell polarity and induce vein formation. Our results reveal synergism between auxin transport and signaling, and their unsuspected control by GNOM in the coordination of tissue cell polarity during vein patterning, one of the most informative expressions of tissue cell polarization in plants.

scholarly journals EpCAM promotes endosomal modulation of the cortical RhoA zone for epithelial organization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cécile Gaston ◽  
Simon De Beco ◽  
Bryant Doss ◽  
Meng Pan ◽  
Estelle Gauquelin ◽  
...  
Keyword(s):  
Cell Shape ◽  
Specific Protein ◽  
Cell Polarization ◽  
Stress Fiber ◽  
Fiber Formation ◽  
Endosomal Trafficking ◽  
Transient Zone ◽  
And Behavior ◽  
Fine Tune

AbstractAt the basis of cell shape and behavior, the organization of actomyosin and its ability to generate forces are widely studied. However, the precise regulation of this contractile network in space and time is unclear. Here, we study the role of the epithelial-specific protein EpCAM, a contractility modulator, in cell shape and motility. We show that EpCAM is required for stress fiber generation and front-rear polarity acquisition at the single cell level. In fact, EpCAM participates in the remodeling of a transient zone of active RhoA at the cortex of spreading epithelial cells. EpCAM and RhoA route together through the Rab35/EHD1 fast recycling pathway. This endosomal pathway spatially organizes GTP-RhoA to fine tune the activity of actomyosin resulting in polarized cell shape and development of intracellular stiffness and traction forces. Impairment of GTP-RhoA endosomal trafficking either by silencing EpCAM or by expressing Rab35/EHD1 mutants prevents proper myosin-II activity, stress fiber formation and ultimately cell polarization. Collectively, this work shows that the coupling between co-trafficking of EpCAM and RhoA, and actomyosin rearrangement is pivotal for cell spreading, and advances our understanding of how biochemical and mechanical properties promote cell plasticity.

scholarly journals Characterization of the Drosophila protein arginine methyltransferases DART1 and DART4

2004 ◽  
Vol 379 (2) ◽  
pp. 283-289 ◽  
Author(s):  
Marie-Chloé BOULANGER ◽  
Tina Branscombe MIRANDA ◽  
Steven CLARKE ◽  
Marco di FRUSCIO ◽  
Beat SUTER ◽  
...  
Keyword(s):  
Rna Binding ◽  
Developmental Stages ◽  
Rna Binding Proteins ◽  
Genetic System ◽  
Arginine Methylation ◽  
Type I ◽  
Protein Arginine Methyltransferases ◽  
Arginine Residues ◽  
Drosophila Protein

The role of arginine methylation in Drosophila melanogaster is unknown. We identified a family of nine PRMTs (protein arginine methyltransferases) by sequence homology with mammalian arginine methyltransferases, which we have named DART1 to DART9 (Drosophilaarginine methyltransferases 1–9). In keeping with the mammalian PRMT nomenclature, DART1, DART4, DART5 and DART7 are the putative homologues of PRMT1, PRMT4, PRMT5 and PRMT7. Other DART family members have a closer resemblance to PRMT1, but do not have identifiable homologues. All nine genes are expressed in Drosophila at various developmental stages. DART1 and DART4 have arginine methyltransferase activity towards substrates, including histones and RNA-binding proteins. Amino acid analysis of the methylated arginine residues confirmed that both DART1 and DART4 catalyse the formation of asymmetrical dimethylated arginine residues and they are type I arginine methyltransferases. The presence of PRMTs in D. melanogaster suggest that flies are a suitable genetic system to study arginine methylation.

scholarly journals The CDC42 Homolog of the Dimorphic FungusPenicillium marneffei Is Required for Correct Cell Polarization during Growth but Not Development

2001 ◽  
Vol 183 (11) ◽  
pp. 3447-3457 ◽  
Author(s):  
Kylie J. Boyce ◽  
Michael J. Hynes ◽  
Alex Andrianopoulos
Keyword(s):  
Cell Shape ◽  
Pathogenic Fungus ◽  
Cell Polarization ◽  
Dominant Negative ◽  
Yeast Cells ◽  
Polarized Growth ◽  
Temperature Dependent ◽  
Human Pathogenic Fungus ◽  
Rho Family

ABSTRACT The opportunistic human pathogenic fungus Penicillium marneffei is dimorphic and is thereby capable of growth either as filamentous multinucleate hyphae or as uninucleate yeast cells which divide by fission. The dimorphic switch is temperature dependent and requires regulated changes in morphology and cell shape. Cdc42p is a Rho family GTPase which in Saccharomyces cerevisiae is required for changes in polarized growth during mating and pseudohyphal development. Cdc42p homologs in higher organisms are also associated with changes in cell shape and polarity. We have cloned a highly conserved CDC42 homolog from P. marneffeinamed cflA. By the generation of dominant-negative and dominant-activated cflA transformants, we have shown that CflA initiates polarized growth and extension of the germ tube and subsequently maintains polarized growth in the vegetative mycelium. CflA is also required for polarization and determination of correct cell shape during yeast-like growth, and active CflA is required for the separation of yeast cells. However, correct cflAfunction is not required for dimorphic switching and does not appear to play a role during the generation of specialized structures during asexual development. In contrast, heterologous expression ofcflA alleles in Aspergillus nidulansprevented conidiation.

scholarly journals Actin and microtubules drive differential aspects of planar cell polarity in multiciliated cells

2011 ◽  
Vol 195 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Michael E. Werner ◽  
Peter Hwang ◽  
Fawn Huisman ◽  
Peter Taborek ◽  
Clare C. Yu ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Planar Cell Polarity ◽  
Cell Polarization ◽  
Actin Dynamics ◽  
Cellular Organization ◽  
Cytoplasmic Microtubule ◽  
Local Coordination ◽  
Multiciliated Cells ◽  
Global Coordination ◽  
Microtubule Networks

Planar cell polarization represents the ability of cells to orient within the plane of a tissue orthogonal to the apical basal axis. The proper polarized function of multiciliated cells requires the coordination of cilia spacing and cilia polarity as well as the timing of cilia beating during metachronal synchrony. The planar cell polarity pathway and hydrodynamic forces have been shown to instruct cilia polarity. In this paper, we show how intracellular effectors interpret polarity to organize cellular morphology in accordance with asymmetric cellular function. We observe that both cellular actin and microtubule networks undergo drastic reorganization, providing differential roles during the polarized organization of cilia. Using computational angular correlation analysis of cilia orientation, we report a graded cellular organization downstream of cell polarity cues. Actin dynamics are required for proper cilia spacing, global coordination of cilia polarity, and coordination of metachronic cilia beating, whereas cytoplasmic microtubule dynamics are required for local coordination of polarity between neighboring cilia.

scholarly journals A bidirectional antagonism between aPKC and Yurt regulates epithelial cell polarity

2014 ◽  
Vol 204 (4) ◽  
pp. 487-495 ◽  
Author(s):  
Clémence L. Gamblin ◽  
Émilie J.-L. Hardy ◽  
François J.-M. Chartier ◽  
Nicolas Bisson ◽  
Patrick Laprise
Keyword(s):  
Epithelial Cell ◽  
Cell Polarity ◽  
Cell Polarization ◽  
Membrane Domains ◽  
Epithelial Cell Polarity ◽  
Kinase C ◽  
The Stability ◽  
Regulatory Loop ◽  
Late Stages ◽  
Apical Localization

During epithelial cell polarization, Yurt (Yrt) is initially confined to the lateral membrane and supports the stability of this membrane domain by repressing the Crumbs-containing apical machinery. At late stages of embryogenesis, the apical recruitment of Yrt restricts the size of the apical membrane. However, the molecular basis sustaining the spatiotemporal dynamics of Yrt remains undefined. In this paper, we report that atypical protein kinase C (aPKC) phosphorylates Yrt to prevent its premature apical localization. A nonphosphorylatable version of Yrt dominantly dismantles the apical domain, showing that its aPKC-mediated exclusion is crucial for epithelial cell polarity. In return, Yrt counteracts aPKC functions to prevent apicalization of the plasma membrane. The ability of Yrt to bind and restrain aPKC signaling is central for its role in polarity, as removal of the aPKC binding site neutralizes Yrt activity. Thus, Yrt and aPKC are involved in a reciprocal antagonistic regulatory loop that contributes to segregation of distinct and mutually exclusive membrane domains in epithelial cells.

scholarly journals Cell shape and substrate stiffness drive actin-based cell polarity

2019 ◽  
Vol 99 (1) ◽  
Author(s):  
Mukund Gupta ◽  
Bryant L. Doss ◽  
Leyla Kocgozlu ◽  
Meng Pan ◽  
René-Marc Mège ◽  
...  
Keyword(s):  
Cell Polarity ◽  
Cell Shape ◽  
Substrate Stiffness
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