A coupled mechano-biochemical model for cell polarity guided anisotropic root growth

Plants develop new organs to adjust their bodies to dynamic changes in the environment. How independent organs achieve anisotropic shapes and polarities is poorly understood. To address this question, we constructed a mechano-biochemical model for Arabidopsis root meristem growth that integrates biologically plausible principles. Computer model simulations demonstrate how differential growth of neighboring tissues results in the initial symmetry-breaking leading to anisotropic root growth. Furthermore, the root growth feeds back on a polar transport network of the growth regulator auxin. Model, predictions are in close agreement with in vivo patterns of anisotropic growth, auxin distribution, and cell polarity, as well as several root phenotypes caused by chemical, mechanical, or genetic perturbations. Our study demonstrates that the combination of tissue mechanics and polar auxin transport organizes anisotropic root growth and cell polarities during organ outgrowth. Therefore, a mobile auxin signal transported through immobile cells drives polarity and growth mechanics to coordinate complex organ development.

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Design principles of plant root morphogenesis

10.1101/2021.01.27.428294 ◽

2021 ◽

Author(s):

Marco Marconi ◽

Marçal Gallemi ◽

Eva Benková ◽

Krzysztof Wabnik

Keyword(s):

Cell Polarity ◽

Plant Root ◽

Design Principles ◽

Tissue Mechanics ◽

Auxin Distribution ◽

Growth Mechanics ◽

Genetic Perturbations ◽

Root Morphogenesis ◽

Stem Cell Populations ◽

Advanced Computer

AbstractUnderstanding how an independent organ develops from the stem cell populations in the process called morphogenesis is a pressing challenge in developmental biology and medicine. Plants build up new organs such as roots to adjust their bodies to dynamic changes in the environment, thereby providing a tractable model to address this challenge. Here, we combined empirical data with advanced computer modeling techniques to build a mechanistic cell-based framework for the morphogenesis of the plant root. Our framework relies on experimentally supported design principles underlying the multi-layered feedback between tissue mechanics, cell growth, and directional cell-to-cell transport of growth regulator auxin. Model simulations reconstruct experimentally-observed patterns of anisotropic growth, auxin distribution, and cell polarity, as well as several root phenotypes caused by chemical, mechanical, or genetic perturbations. Furthermore, our model provides new insights into mechanisms of sustained root growth and cell polarity establishment. This work reveals that mobile auxin signal feeds back on cell polarity and growth mechanics to instruct the morphogenesis of an independent organ.

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Planar differential growth rates determine the position of folds in complex epithelia

10.1101/515528 ◽

2019 ◽

Cited By ~ 2

Author(s):

Melda Tozluo◻lu ◽

Maria Duda ◽

Natalie J. Kirkland ◽

Ricardo Barrientos ◽

Jemima J. Burden ◽

...

Keyword(s):

Growth Rates ◽

Tissue Mechanics ◽

Differential Growth ◽

Spatial And Temporal Heterogeneity ◽

Main Driver ◽

Fold Formation ◽

Epithelial Sheets ◽

Open Question ◽

Planar Growth

SummaryFolding is a fundamental process shaping epithelial sheets into 3D architectures of organs. Initial positioning of folds is the foundation for the emergence of correct tissue morphology. Mechanisms forming individual folds have been studied, yet the precise positioning of the folds in complex, multi-folded epithelia is an open question. We present a model of morphogenesis, encompassing local differential growth, and tissue mechanics to investigate tissue fold positioning. We use Drosophila melanogaster wing imaginal disc as our model system, and show that there is spatial and temporal heterogeneity in its planar growth rates. This planar differential growth is the main driver for positioning the folds. Increased stiffness of the apical layer and confinement by the basement membrane drive fold formation. These influence fold positions to a lesser degree. The model successfully predicts the emergent morphology of wingless spade mutant in vivo, via perturbations solely on planar differential growth rates in silico.

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The ectopic expression of Arabidopsis glucosyltransferase UGT74D1 affects leaf positioning through modulating indole-3-acetic acid homeostasis

Scientific Reports ◽

10.1038/s41598-021-81016-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Shanghui Jin ◽

Bingkai Hou ◽

Guizhi Zhang

Keyword(s):

Acetic Acid ◽

Ectopic Expression ◽

Leaf Angle ◽

Kinase Substrate ◽

Auxin Distribution ◽

Leaf Tissues ◽

Photosynthesis Efficiency ◽

Indole 3 Acetic Acid

AbstractLeaf angle is an important agronomic trait affecting photosynthesis efficiency and crop yield. Although the mechanisms involved in the leaf angle control are intensively studied in monocots, factors contribute to the leaf angle in dicots are largely unknown. In this article, we explored the physiological roles of an Arabidopsis glucosyltransferase, UGT74D1, which have been proved to be indole-3-acetic acid (IAA) glucosyltransferase in vitro. We found that UGT74D1 possessed the enzymatic activity toward IAA glucosylation in vivo and its expression was induced by auxins. The ectopically expressed UGT74D1 obviously reduced the leaf angle with an altered IAA level, auxin distribution and cell size in leaf tissues. The expression of several key genes involved in the leaf shaping and leaf positioning, including PHYTOCHROME KINASE SUBSTRATE (PKS) genes and TEOSINTE BRANCHED1, CYCLOIDEA, and PCF (TCP) genes, were dramatically changed by ectopic expression of UGT74D1. In addition, clear transcription changes of YUCCA genes and other auxin related genes can be observed in overexpression lines. Taken together, our data indicate that glucosyltransferase UGT74D1 could affect leaf positioning through modulating auxin homeostasis and regulating transcription of PKS and TCP genes, suggesting a potential new role of UGT74D1 in regulation of leaf angle in dicot Arabidopsis.

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LKB1 and AMPK maintain epithelial cell polarity under energetic stress

The Journal of Cell Biology ◽

10.1083/jcb.200702053 ◽

2007 ◽

Vol 177 (3) ◽

pp. 387-392 ◽

Cited By ~ 134

Author(s):

Vincent Mirouse ◽

Lance L. Swick ◽

Nevzat Kazgan ◽

Daniel St Johnston ◽

Jay E. Brenman

Keyword(s):

Tumor Suppressor ◽

Cell Polarity ◽

Growth Control ◽

Epithelial Polarity ◽

Energy Status ◽

Ampk Signaling ◽

Cellular Energy ◽

Energetic Stress ◽

Stress Dependent

LKB1 is mutated in both familial and spontaneous tumors, and acts as a master kinase that activates the PAR-1 polarity kinase and the adenosine 5′monophosphate–activated kinase (AMPK). This has led to the hypothesis that LKB1 acts as a tumor suppressor because it is required to maintain cell polarity and growth control through PAR-1 and AMPK, respectively. However, the genetic analysis of LKB1–AMPK signaling in vertebrates has been complicated by the existence of multiple redundant AMPK subunits. We describe the identification of mutations in the single Drosophila melanogaster AMPK catalytic subunit AMPKα. Surprisingly, ampkα mutant epithelial cells lose their polarity and overproliferate under energetic stress. LKB1 is required in vivo for AMPK activation, and lkb1 mutations cause similar energetic stress–dependent phenotypes to ampkα mutations. Furthermore, lkb1 phenotypes are rescued by a phosphomimetic version of AMPKα. Thus, LKB1 signals through AMPK to coordinate epithelial polarity and proliferation with cellular energy status, and this might underlie the tumor suppressor function of LKB1.

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Discs large 1 controls daughter-cell polarity after cytokinesis in vertebrate morphogenesis

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1713959115 ◽

2018 ◽

Vol 115 (46) ◽

pp. E10859-E10868 ◽

Cited By ~ 5

Author(s):

Yuwei Li ◽

Jason A. Junge ◽

Cosimo Arnesano ◽

Garrett G. Gross ◽

Jeffrey H. Miner ◽

...

Keyword(s):

Cell Polarity ◽

Protein Interactions ◽

Protein Function ◽

Resonance Energy Transfer ◽

Resonance Energy ◽

Explant Culture ◽

Scaffolding Protein ◽

Fluorescence Lifetime Imaging ◽

Discs Large

Vertebrate embryogenesis and organogenesis are driven by cell biological processes, ranging from mitosis and migration to changes in cell size and polarity, but their control and causal relationships are not fully defined. Here, we use the developing limb skeleton to better define the relationships between mitosis and cell polarity. We combine protein-tagging and -perturbation reagents with advanced in vivo imaging to assess the role of Discs large 1 (Dlg1), a membrane-associated scaffolding protein, in mediating the spatiotemporal relationship between cytokinesis and cell polarity. Our results reveal that Dlg1 is enriched at the midbody during cytokinesis and that its multimerization is essential for the normal polarity of daughter cells. Defects in this process alter tissue dimensions without impacting other cellular processes. Our results extend the conventional view that division orientation is established at metaphase and anaphase and suggest that multiple mechanisms act at distinct phases of the cell cycle to transmit cell polarity. The approach employed can be used in other systems, as it offers a robust means to follow and to eliminate protein function and extends the Phasor approach for studying in vivo protein interactions by frequency-domain fluorescence lifetime imaging microscopy of Förster resonance energy transfer (FLIM-FRET) to organotypic explant culture.

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A small proportion of Talin molecules transmit forces to achieve muscle attachment in vivo

10.1101/446336 ◽

2018 ◽

Cited By ~ 2

Author(s):

Sandra B. Lemke ◽

Thomas Weidemann ◽

Anna-Lena Cost ◽

Carsten Grashoff ◽

Frank Schnorrer

Keyword(s):

Tissue Mechanics ◽

Correlation Spectroscopy ◽

Mechanical Forces ◽

Muscle Attachment ◽

Cell Fate Decisions ◽

Mammalian Cell Lines ◽

Attachment Sites ◽

Molecular Forces ◽

Muscle Attachment Sites

Cells in a developing organism are subjected to particular mechanical forces, which shape tissues and instruct cell fate decisions. How these forces are sensed and transmitted at the molecular level is thus an important question, which has mainly been investigated in cultured cells in vitro. Here, we elucidate how mechanical forces are transmitted in an intact organism. We studied Drosophila muscle attachment sites, which experience high mechanical forces during development and require integrin-mediated adhesion for stable attachment to tendons. Hence, we quantified molecular forces across the essential integrin-binding protein Talin, which links integrin to the actin cytoskeleton. Generating flies expressing three FRET-based Talin tension sensors reporting different force levels between 1 and 11 pN enabled us to quantify physiologically-relevant, molecular forces. By measuring primary Drosophila muscle cells, we demonstrate that Drosophila Talin experiences mechanical forces in cell culture that are similar to those previously reported for Talin in mammalian cell lines. However, in vivo force measurements at developing flight muscle attachment sites revealed that average forces across Talin are comparatively low and decrease even further while attachments mature and tissue-level tension increases. Concomitantly, Talin concentration at attachment sites increases five-fold as quantified by fluorescence correlation spectroscopy, suggesting that only few Talin molecules are mechanically engaged at any given time. We therefore propose that high tissue forces are shared amongst a large excess of adhesion molecules of which less than 15% are experiencing detectable forces at the same time. Our findings define an important new concept of how cells can adapt to changes in tissue mechanics to prevent mechanical failure in vivo.

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Genetic engineering for in vivo optical interrogation of neuronal responses to cell type-specific silencing

10.1101/2021.01.13.426508 ◽

2021 ◽

Author(s):

Firat Terzi ◽

Johannes Knabbe ◽

Sidney B. Cambridge

Keyword(s):

High Resolution ◽

Genetic Engineering ◽

Transgene Expression ◽

Neuronal Morphology ◽

Dependent Manner ◽

Cell Type ◽

Fluorescent Marker ◽

Genetic Perturbations ◽

Cell Type Specific

SummaryGenetic engineering of quintuple transgenic brain tissue was used to establish a low background, Cre-dependent version of the inducible Tet-On system for fast, cell type-specific transgene expression in vivo. Co-expression of a constitutive, Cre-dependent fluorescent marker selectively allowed single cell analyses before and after inducible, tet-dependent transgene expression. Here, we used this method for acute, high-resolution manipulation of neuronal activity in the living brain. Single induction of the potassium channel Kir2.1 produced cell type-specific silencing within hours that lasted for at least three days. Longitudinal in vivo imaging of spontaneous calcium transients and neuronal morphology demonstrated that prolonged silencing did not alter spine densities or synaptic input strength. Furthermore, selective induction of Kir2.1 in parvalbumin interneurons increased the activity of surrounding neurons in a distance-dependent manner. This high-resolution, inducible interference and interval imaging of individual cells (high I5, ‘HighFive’) method thus allows visualizing temporally precise, genetic perturbations of defined cells.

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Progressive recruitment of distal MEC-4 channels determines touch response strength in C. elegans

10.1101/587014 ◽

2019 ◽

Cited By ~ 1

Author(s):

S. Katta ◽

A. Sanzeni ◽

A. Das ◽

M. Vergassola ◽

M.B. Goodman

Keyword(s):

Temporal Dynamics ◽

Mechanical Strain ◽

Tissue Mechanics ◽

Mechanical Stimuli ◽

Patch Clamp Recording ◽

Open Probability ◽

C Elegans ◽

Somatosensory Neurons ◽

Touch Response

AbstractTouch deforms, or strains, the skin beyond the immediate point of contact. The spatiotemporal nature of the touch-induced strain fields depend on the mechanical properties of the skin and the tissues below. Somatosensory neurons that sense touch branch out within the skin and rely on a set of mechano-electrical transduction channels distributed within their dendrites to detect mechanical stimuli. Here, we sought to understand how tissue mechanics shape touch-induced mechanical strain across the skin over time and how individual channels located in different regions of the strain field contribute to the overall touch response. We leveraged C. elegans’ touch receptor neurons (TRNs) as a simple model amenable to in vivo whole-cell patch clamp recording and an integrated experimental-computational approach to dissect the mechanisms underlying the spatial and temporal dynamics that we observed. Consistent with the idea that strain is produced at a distance, we show that delivering strong stimuli outside the anatomical extent of the neuron is sufficient to evoke MRCs. The amplitude and kinetics of the MRCs depended on both stimulus displacement and speed. Finally, we found that the main factor responsible for touch sensitivity is the recruitment of progressively more distant channels by stronger stimuli, rather than modulation of channel open probability. This principle may generalize to somatosensory neurons with more complex morphologies.SummaryThrough experiment and simulation, Katta et al. reveal that pushing faster and deeper recruits more and more distant mechano-electrical transduction channels during touch. The net result is a dynamic receptive field whose size and shape depends on tissue mechanics, stimulus parameters, and channel distribution within sensory neurons.

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The core planar cell polarity gene, Vangl2 , directs adult corneal epithelial cell alignment and migration

Royal Society Open Science ◽

10.1098/rsos.160658 ◽

2016 ◽

Vol 3 (10) ◽

pp. 160658 ◽

Cited By ~ 11

Author(s):

Amy S. Findlay ◽

D. Alessio Panzica ◽

Petr Walczysko ◽

Amy B. Holt ◽

Deborah J. Henderson ◽

...

Keyword(s):

Cell Migration ◽

Epithelial Cells ◽

Cell Polarity ◽

Corneal Epithelium ◽

Planar Cell Polarity ◽

Corneal Epithelial Cell ◽

Corneal Epithelial Cells ◽

Corneal Epithelial ◽

The Core

This study shows that the core planar cell polarity (PCP) genes direct the aligned cell migration in the adult corneal epithelium, a stratified squamous epithelium on the outer surface of the vertebrate eye. Expression of multiple core PCP genes was demonstrated in the adult corneal epithelium. PCP components were manipulated genetically and pharmacologically in human and mouse corneal epithelial cells in vivo and in vitro . Knockdown of VANGL2 reduced the directional component of migration of human corneal epithelial (HCE) cells without affecting speed. It was shown that signalling through PCP mediators, dishevelled, dishevelled-associated activator of morphogenesis and Rho-associated protein kinase directs the alignment of HCE cells by affecting cytoskeletal reorganization. Cells in which VANGL2 was disrupted tended to misalign on grooved surfaces and migrate across, rather than parallel to the grooves. Adult corneal epithelial cells in which Vangl2 had been conditionally deleted showed a reduced rate of wound-healing migration. Conditional deletion of Vangl2 in the mouse corneal epithelium ablated the normal highly stereotyped patterns of centripetal cell migration in vivo from the periphery (limbus) to the centre of the cornea. Corneal opacity owing to chronic wounding is a major cause of degenerative blindness across the world, and this study shows that Vangl2 activity is required for directional corneal epithelial migration.

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Auxin methylation is required for differential growth inArabidopsis

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1806565115 ◽

2018 ◽

Vol 115 (26) ◽

pp. 6864-6869 ◽

Cited By ~ 10

Author(s):

Mohamad Abbas ◽

Jorge Hernández-García ◽

Stephan Pollmann ◽

Sophia L. Samodelov ◽

Martina Kolb ◽

...

Keyword(s):

Gene Expression ◽

Auxin Transport ◽

Polar Auxin Transport ◽

Asymmetric Distribution ◽

Loss Of Function ◽

Differential Growth ◽

Specific Expression ◽

Auxin Homeostasis ◽

Auxin Distribution ◽

Gene Expression Levels

Asymmetric auxin distribution is instrumental for the differential growth that causes organ bending on tropic stimuli and curvatures during plant development. Local differences in auxin concentrations are achieved mainly by polarized cellular distribution of PIN auxin transporters, but whether other mechanisms involving auxin homeostasis are also relevant for the formation of auxin gradients is not clear. Here we show that auxin methylation is required for asymmetric auxin distribution across the hypocotyl, particularly during its response to gravity. We found that loss-of-function mutants inArabidopsis IAA CARBOXYL METHYLTRANSFERASE1(IAMT1) prematurely unfold the apical hook, and that their hypocotyls are impaired in gravitropic reorientation. This defect is linked to an auxin-dependent increase inPINgene expression, leading to an increased polar auxin transport and lack of asymmetric distribution of PIN3 in theiamt1mutant. Gravitropic reorientation in theiamt1mutant could be restored with either endodermis-specific expression ofIAMT1or partial inhibition of polar auxin transport, which also results in normalPINgene expression levels. We propose that IAA methylation is necessary in gravity-sensing cells to restrict polar auxin transport within the range of auxin levels that allow for differential responses.

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