scholarly journals A synthetic morphogenic membrane system that responds with self-organized shape changes to local light cues

2018 ◽  
Author(s):  
Konstantin Gavriljuk ◽  
Bruno Scocozza ◽  
Farid Ghasemalizadeh ◽  
Akhilesh P. Nandan ◽  
Manuel Campos Medina ◽  
...  
Keyword(s):  
Chemical Potential ◽  
Rho Gtpase ◽  
Membrane System ◽  
Signaling System ◽  
Extracellular Signals ◽  
Self Organized ◽  
Cellular Morphogenesis ◽  
Membrane Deformations ◽  
Shape Changes ◽  
Dynamic Microtubule

SUMMARYReconstitution of artificial cells capable of transducing extracellular signals into cytoskeletal changes is a challenge in synthetic biology that will reveal fundamental principles of non-equilibrium phenomena of cellular morphogenesis and information processing. Here, we generated a ‘life-like’ Synthetic Morphogenic Membrane System (SynMMS) by encapsulating a dynamic microtubule (MT) aster and a light-inducible signaling system driven by GTP/ATP chemical potential into cell-sized vesicles. The biomimetic design of the light-induced signaling system embodies the operational principle of morphogen induced Rho-GTPase signal transduction in cells. Activation of synthetic signaling promotes membrane-deforming growth of MT-filaments by dynamically elevating the membrane-proximal concentration of tubulin. The resulting membrane deformations enable the recursive coupling of the MT-aster with the signaling system, creating global self-organized morphologies that reorganize towards external light cues in dependence on prior sensory experience that is stored in the dynamically maintained morphology. SynMMS thereby signifies a step towards bio-inspired engineering of self-organized cellular morphogenesis.

scholarly journals A self-organized synthetic morphogenic liposome responds with shape changes to local light cues

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Konstantin Gavriljuk ◽  
Bruno Scocozza ◽  
Farid Ghasemalizadeh ◽  
Hans Seidel ◽  
Akhilesh P. Nandan ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Chemical Potential ◽  
Rho Gtpase ◽  
Membrane System ◽  
Signaling System ◽  
Basic Principles ◽  
Extracellular Signals ◽  
Self Organized ◽  
Cellular Signal ◽  
Membrane Deformations

AbstractReconstituting artificial proto-cells capable of transducing extracellular signals into cytoskeletal changes can reveal fundamental principles of how non-equilibrium phenomena in cellular signal transduction affect morphogenesis. Here, we generated a Synthetic Morphogenic Membrane System (SynMMS) by encapsulating a dynamic microtubule (MT) aster and a light-inducible signaling system driven by GTP/ATP chemical potential into cell-sized liposomes. Responding to light cues in analogy to morphogens, this biomimetic design embodies basic principles of localized Rho-GTPase signal transduction that generate an intracellular MT-regulator signaling gradient. Light-induced signaling promotes membrane-deforming growth of MT-filaments by dynamically elevating the membrane-proximal tubulin concentration. The resulting membrane deformations enable recursive coupling of the MT-aster with the signaling system, which generates global self-organized morphologies that reorganize towards local external cues in dependence on prior shape. SynMMS thereby signifies a step towards bio-inspired engineering of self-organized cellular morphogenesis.

scholarly journals Self-organized cytoskeletal alignment during Drosophila mesoderm invagination

2020 ◽  
Vol 375 (1809) ◽  
pp. 20190551 ◽  
Author(s):  
Adam C. Martin
Keyword(s):  
Self Organization ◽  
Mechanical Forces ◽  
Feedback Process ◽  
Wild Type ◽  
Tissue Morphogenesis ◽  
Cell Behaviour ◽  
Feedback Mechanisms ◽  
Self Organized ◽  
Actomyosin Cytoskeleton ◽  
Shape Changes

During tissue morphogenesis, mechanical forces are propagated across tissues, resulting in tissue shape changes. These forces in turn can influence cell behaviour, leading to a feedback process that can be described as self-organizing. Here, I discuss cytoskeletal self-organization and point to evidence that suggests its role in directing force during morphogenesis. During Drosophila mesoderm invagination, the shape of the region of cells that initiates constriction creates a mechanical pattern that in turn aligns the cytoskeleton with the axis of greatest resistance to contraction. The wild-type direction of the force controls the shape and orientation of the invaginating mesoderm. Given the ability of the actomyosin cytoskeleton to self-organize, these types of feedback mechanisms are likely to play important roles in a range of different morphogenetic events. This article is part of the discussion meeting issue ‘Contemporary morphogenesis'.

Shape Transition in Self-Organized InAs/InP Nanostructures

2001 ◽  
Vol 707 ◽  
Author(s):  
H.R. Gutiérrez ◽  
M.A. Cotta ◽  
M.M.G. de Carvalho
Keyword(s):  
Quantum Dots ◽  
Driving Force ◽  
Anisotropic Diffusion ◽  
Chemical Potential ◽  
Quantum Wires ◽  
Shape Transition ◽  
Self Organized ◽  
Self Assembled ◽  
Inp Substrates ◽  
Stable Shape

ABSTRACTIn this letter we report the transition from self-assembled InAs quantum-wires to quantum-dots grown on (100) InP substrates. This transition is obtained when the wires are annealed at the growth temperature. Our results suggest that the quantum-wires are a metastable shape originated from the anisotropic diffusion over the InP buffer layer during the formation of the first InAs monolayer. The wires evolve to a more stable shape (dot) during the annealing. The driving force for the transition is associated with variations in the elastic energy and hence in the chemical potential produced by height fluctuations along the wire. The regions along the wires with no height variations are more stable allowing the formation of complex, self-assembled nanostructures such as dots interconnected by wires.

scholarly journals Self-organized shape dynamics of active surfaces

2018 ◽  
Vol 116 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Alexander Mietke ◽  
Frank Jülicher ◽  
Ivo F. Sbalzarini
Keyword(s):  
Numerical Approach ◽  
Spontaneous Generation ◽  
Advective Transport ◽  
Shape Dynamics ◽  
Active Surfaces ◽  
Self Organized ◽  
Integral Element ◽  
Epithelial Sheets ◽  
Shape Changes

Mechanochemical processes in thin biological structures, such as the cellular cortex or epithelial sheets, play a key role during the morphogenesis of cells and tissues. In particular, they are responsible for the dynamical organization of active stresses that lead to flows and deformations of the material. Consequently, advective transport redistributes force-generating molecules and thereby contributes to a complex mechanochemical feedback loop. It has been shown in fixed geometries that this mechanism enables patterning, but the interplay of these processes with shape changes of the material remains to be explored. In this work, we study the fully self-organized shape dynamics using the theory of active fluids on deforming surfaces and develop a numerical approach to solve the corresponding force and torque balance equations. We describe the spontaneous generation of nontrivial surface shapes, shape oscillations, and directed surface flows that resemble peristaltic waves from self-organized, mechanochemical processes on the deforming surface. Our approach provides opportunities to explore the dynamics of self-organized active surfaces and can help to understand the role of shape as an integral element of the mechanochemical organization of morphogenetic processes.

scholarly journals Two Pathways through Cdc42 Couple the N-Formyl Receptor to Actin Nucleation in Permeabilized Human Neutrophils

2000 ◽  
Vol 150 (4) ◽  
pp. 785-796 ◽  
Author(s):  
M. Glogauer ◽  
J. Hartwig ◽  
T. Stossel
Keyword(s):  
Rho Gtpase ◽  
Human Neutrophils ◽  
Actin Nucleation ◽  
Maximal Inhibition ◽  
Receptor Stimulation ◽  
Binding Peptide ◽  
Inhibitory Peptides ◽  
Alternate Pathway ◽  
Fmlp Receptor ◽  
Shape Changes

We developed a permeabilization method that retains coupling between N-formyl-methionyl-leucyl-phenylalanine tripeptide (FMLP) receptor stimulation, shape changes, and barbed-end actin nucleation in human neutrophils. Using GTP analogues, phosphoinositides, a phosphoinositide-binding peptide, constitutively active or inactive Rho GTPase mutants, and activating or inhibitory peptides derived from neural Wiskott-Aldrich syndrome family proteins (N-WASP), we identified signaling pathways leading from the FMLP receptor to actin nucleation that require Cdc42, but then diverge. One branch traverses the actin nucleation pathway involving N-WASP and the Arp2/3 complex, whereas the other operates through active Rac to promote actin nucleation. Both pathways depend on phosphoinositide expression. Since maximal inhibition of the Arp2/3 pathway leaves an N17Rac inhibitable alternate pathway intact, we conclude that this alternate involves phosphoinositide-mediated uncapping of actin filament barbed ends.

A self-organized biomechanical network drives shape changes during tissue morphogenesis

Nature ◽  
2015 ◽  
Vol 524 (7565) ◽  
pp. 351-355 ◽  
Author(s):  
Akankshi Munjal ◽  
Jean-Marc Philippe ◽  
Edwin Munro ◽  
Thomas Lecuit
Keyword(s):  
Tissue Morphogenesis ◽  
Self Organized ◽  
Shape Changes

scholarly journals MICAL1 activation by PAK1 mediates actin filament disassembly

2021 ◽  
Author(s):  
David J. McGarry ◽  
Giovanni Castino ◽  
Sergio Lilla ◽  
Sara Zanivan ◽  
Michael F. Olson
Keyword(s):  
Signaling Pathways ◽  
Rho Gtpase ◽  
Nervous System Development ◽  
Mass Spectrometry Analysis ◽  
Actin Binding ◽  
Genetic Syndrome ◽  
Temporal Epilepsy ◽  
Amino Terminal ◽  
Extracellular Signals ◽  
Carboxyl Terminal

SummaryThe MICAL1 monooxygenase has emerged as an important regulator of filamentous actin (F-actin) structures that contribute to numerous processes including nervous system development, cell morphology, motility, viability and cytokinesis [1–4]. Activating MICAL1 mutations have been linked with autosomal-dominant lateral temporal epilepsy, a genetic syndrome characterized by focal seizures with auditory symptoms [5], emphasizing the need for tight control of MICAL1 activity. F-actin binding to MICAL1 stimulates catalytic activity, resulting in the oxidation of actin methionine residues that promote F-actin disassembly [6, 7]. Although MICAL1 has been shown to be regulated via interactions of the autoinhibitory carboxyl-terminal coiled-coil region [8] with RAB8, RAB10 and RAB35 GTPases [9–12], or Plexin transmembrane receptors [13, 14], a mechanistic link between the RHO GTPase signaling pathways that control actin cytoskeleton dynamics and the regulation of MICAL1 activity had not been established. Here we show that the CDC42 GTPase effector PAK1 serine/threonine kinase associates with and phosphorylates MICAL1 on serine 817 (Ser817) and 960 (Ser960) residues, leading to accelerated F-actin disassembly. Deletion analysis mapped PAK1 binding to the amino-terminal catalytic monooxygenase and calponin domains, distinct from the carboxyl-terminal proteinprotein interaction domain. Stimulation of cells with extracellular ligands including basic fibroblast growth factor (FGF2) led to significant PAK-dependent Ser960 phosphorylation, thus linking extracellular signals to MICAL1 phosphorylation. Moreover, mass spectrometry analysis revealed that co-expression of MICAL1 with CDC42 and active PAK1 resulted in hundreds of proteins increasing their association with MICAL1, including the previously described MICAL1-interacting protein RAB10 [15]. These results provide the first insight into a redox-mediated actin disassembly pathway linking extracellular signals to cytoskeleton regulation via a RHO GTPase family member, and reveal a novel means of communication between RHO and RAB GTPase signaling pathways.

Shape Transition in Self-Organized InAs/InP Nanostructures

2001 ◽  
Vol 696 ◽  
Author(s):  
H.R. Gutiérrez ◽  
M.A. Cotta ◽  
M.M.G. de Carvalho
Keyword(s):  
Growth Temperature ◽  
Driving Force ◽  
Anisotropic Diffusion ◽  
Chemical Potential ◽  
Quantum Wires ◽  
Shape Transition ◽  
Self Organized ◽  
Self Assembled ◽  
Inp Substrates ◽  
Stable Shape

AbstractIn this letter we report the transition from self-assembled InAs quantum-wires to quantumdots grown on (100) InP substrates. This transition is obtained when the wires are annealed at the growth temperature. Our results suggest that the quantum-wires are a metastable shape originated from the anisotropic diffusion over the InP buffer layer during the formation of the first InAs monolayer. The wires evolve to a more stable shape (dot) during the annealing. The driving force for the transition is associated with variations in the elastic energy and hence in the chemical potential produced by height fluctuations along the wire. The regions along the wires with no height variations are more stable allowing the formation of complex, self-assembled nanostructures such as dots interconnected by wires.

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