scholarly journals Self-organization of Tissue Growth by Interfacial Mechanical Interactions in Multi-layered Systems

2021 ◽  
Author(s):  
Tailin Chen ◽  
Yan Zhao ◽  
Xinbin Zhao ◽  
Shukai Li ◽  
Jialing Cao ◽  
...  
Keyword(s):  
Asymmetric Cell Division ◽  
Size Control ◽  
Tissue Growth ◽  
Cell Junction ◽  
Adhesion Forces ◽  
Layered Systems ◽  
Differential Growth ◽  
Cell Sheets ◽  
Self Organized ◽  
3D Deformation

Morphogenesis is a spatially and temporally regulated process involved in various physiological and pathological transformations. In addition to the associated biochemical factors, the physical regulation of morphogenesis has attracted increasing attention. However, the driving force of morphogenesis initiation remains elusive. Here, we show that during the growth of multi-layered tissues, morphogenetic process can be self-organized by the progression of compression gradient stemmed from the interfacial mechanical interactions between layers. In tissues with low fluidity, the compression gradient is progressively strengthened during differential growth between layers and induces stratification through triggering symmetric-to-asymmetric cell division reorientation at the critical tissue size. In tissues with higher fluidity, compression gradient is dynamic and induces 2D in-plane morphogenesis instead of 3D deformation accompanied with cell junction remodeling regulated cell rearrangement. Morphogenesis can be tuned by manipulating tissue fluidity, cell adhesion forces and mechanical properties to influence the progression of compression gradient during the development of cultured cell sheets and chicken embryos. Together, the progression of compression gradient regulated by interfacial mechanical interaction provides a conserved mechanism underlying morphogenesis initiation and size control during tissue growth.

scholarly journals Xyloglucan Remodeling Defines Auxin-Dependent Differential Tissue Expansion in Plants

2021 ◽  
Vol 22 (17) ◽  
pp. 9222 ◽  
Author(s):  
Silvia Melina Velasquez ◽  
Xiaoyuan Guo ◽  
Marçal Gallemi ◽  
Bibek Aryal ◽  
Peter Venhuizen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Growth Control ◽  
Size Control ◽  
Tissue Expansion ◽  
Major Type ◽  
Hypocotyl Growth ◽  
Differential Growth ◽  
Rigid Cell Wall ◽  
Molecular Complexity ◽  
Genetic Interference

Size control is a fundamental question in biology, showing incremental complexity in plants, whose cells possess a rigid cell wall. The phytohormone auxin is a vital growth regulator with central importance for differential growth control. Our results indicate that auxin-reliant growth programs affect the molecular complexity of xyloglucans, the major type of cell wall hemicellulose in eudicots. Auxin-dependent induction and repression of growth coincide with reduced and enhanced molecular complexity of xyloglucans, respectively. In agreement with a proposed function in growth control, genetic interference with xyloglucan side decorations distinctly modulates auxin-dependent differential growth rates. Our work proposes that auxin-dependent growth programs have a spatially defined effect on xyloglucan’s molecular structure, which in turn affects cell wall mechanics and specifies differential, gravitropic hypocotyl growth.

scholarly journals Fabrication of TiO2 Nanotube by Electrochemical Anodization: Toward Photocatalytic Application

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
O. Zakir ◽  
R. Idouhli ◽  
M. Elyaagoubi ◽  
M. Khadiri ◽  
A. Aityoub ◽  
...  
Keyword(s):  
Tio2 Nanotubes ◽  
Pure Titanium ◽  
Size Control ◽  
Ammonium Fluoride ◽  
Electrode System ◽  
Electrochemical Anodization ◽  
Voltage Range ◽  
X Ray ◽  
Self Organized ◽  
Type Semiconductor

In this study, a self-organized nanotubular titanium dioxide (TiO2) array was successfully produced by anodizing pure titanium in a mixture of glycerol, distilled water (8% vol.), and ammonium fluoride using a dual electrode system. The size control and distribution of the nanopores were performed in a DC voltage range varying from 30 V to 60 V. The diameter of TiO2 nanopores varies from 59 to 128 nm depending on the anodizing voltage. Energy-dispersive X-ray spectroscopy (EDX) analysis reveals that the as-prepared films are essentially composed of TiO2. According to the X-ray diffraction (XRD) and Raman spectroscopy analysis, the nanotubular arrays of TiO2 annealed at 600°C for 2 hours are composed of a phase mixture of anatase and rutile. Mott-Schottky analysis showed that the TiO2 nanotubes are consistent with an n-type semiconductor with a donor density of about 1017 cm-3. Preliminary results on the photocatalytic degradation of a pharmaceutical pollutant showed that the TiO2 nanotubes can be used as a promising material for application in wastewater treatment.

scholarly journals Theory of branching morphogenesis by local interactions and global guidance

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Mehmet Can Uçar ◽  
Dmitrii Kamenev ◽  
Kazunori Sunadome ◽  
Dominik Fachet ◽  
Francois Lallemend ◽  
...  
Keyword(s):  
Scaling Law ◽  
Domain Size ◽  
Branching Morphogenesis ◽  
Tissue Growth ◽  
Regulatory Mechanisms ◽  
Local Interactions ◽  
Self Organized ◽  
Global Guidance ◽  
Different Types

AbstractBranching morphogenesis governs the formation of many organs such as lung, kidney, and the neurovascular system. Many studies have explored system-specific molecular and cellular regulatory mechanisms, as well as self-organizing rules underlying branching morphogenesis. However, in addition to local cues, branched tissue growth can also be influenced by global guidance. Here, we develop a theoretical framework for a stochastic self-organized branching process in the presence of external cues. Combining analytical theory with numerical simulations, we predict differential signatures of global vs. local regulatory mechanisms on the branching pattern, such as angle distributions, domain size, and space-filling efficiency. We find that branch alignment follows a generic scaling law determined by the strength of global guidance, while local interactions influence the tissue density but not its overall territory. Finally, using zebrafish innervation as a model system, we test these key features of the model experimentally. Our work thus provides quantitative predictions to disentangle the role of different types of cues in shaping branched structures across scales.

scholarly journals The Hippo Pathway: Biology and Pathophysiology

2019 ◽  
Vol 88 (1) ◽  
pp. 577-604 ◽  
Author(s):  
Shenghong Ma ◽  
Zhipeng Meng ◽  
Rui Chen ◽  
Kun-Liang Guan
Keyword(s):  
Molecular Mechanisms ◽  
Hippo Pathway ◽  
Size Control ◽  
Tissue Growth ◽  
Cell Contact ◽  
Energy Status ◽  
Downstream Effectors ◽  
Kinase Cascade ◽  
Fate Decision ◽  
The Hippo Pathway

The Hippo pathway was initially discovered in Drosophila melanogaster as a key regulator of tissue growth. It is an evolutionarily conserved signaling cascade regulating numerous biological processes, including cell growth and fate decision, organ size control, and regeneration. The core of the Hippo pathway in mammals consists of a kinase cascade, MST1/2 and LATS1/2, as well as downstream effectors, transcriptional coactivators YAP and TAZ. These core components of the Hippo pathway control transcriptional programs involved in cell proliferation, survival, mobility, stemness, and differentiation. The Hippo pathway is tightly regulated by both intrinsic and extrinsic signals, such as mechanical force, cell–cell contact, polarity, energy status, stress, and many diffusible hormonal factors, the majority of which act through G protein–coupled receptors. Here, we review the current understanding of molecular mechanisms by which signals regulate the Hippo pathway with an emphasis on mechanotransduction and the effects of this pathway on basic biology and human diseases.

scholarly journals Stress generation, relaxation and size control in confined tumor growth

2019 ◽  
Author(s):  
H. Yan ◽  
D. Ramirez-Guerrero ◽  
J. Lowengrub ◽  
M. Wu
Keyword(s):  
Stress Relaxation ◽  
Malignant Tumors ◽  
Size Control ◽  
Maxwell Model ◽  
Stress Generation ◽  
Current Position ◽  
Volumetric Growth ◽  
Differential Growth ◽  
Elastic Stresses ◽  
Mechanical Feedback

Experiments on tumor spheroids have shown that compressive stress from their environment can reversibly decrease tumor expansion rates and final sizes. Stress release experiments show that nonuniform anisotropic elastic stresses can be distributed throughout. The elastic stresses are maintained by structural proteins and adhesive molecules, and can be actively relaxed by a variety of biophysical processes. In this letter, we present a new continuum model to investigate how the instantaneous elastic moduli and active stress relaxation, in conjunction with mechanical feedback machinery within cells, regulate the sizes of and stress distributions within growing tumors in the presence of external physical confinement and gradients of growth-promoting chemical fields. We introduce an adaptive reference map that relates the current position with the reference position but adapts to the current position in the Eulerian frame (lab coordinates) via relaxation. This type of stress relaxation is similar to but simpler than the classical Maxwell model of viscoelasticity. By fitting the model to experimental data from two independent studies of tumor spheroid growth, treating the tumors as incompressible, neo-Hookean elastic materials, we find that the rates of stress relaxation of tumor tissues can be comparable to volumetric growth rates. Our study provides insight on how the biophysical properties of the tumor and host microenvironment, mechanical feedback control and diffusion-limited differential growth act in concert to regulate spatial patterns of stress and growth. When the tumor is stiffer than the host, our model predicts tumors are more able to change their size and mechanical state autonomously, which may help to explain why increased tumor stiffness is an established hallmark of malignant tumors.PACS numbers: 46.15.Cc,62.20.mt,68.55.at,87.19.1x,87.19.R-

scholarly journals Xyloglucan remodelling defines differential tissue expansion in plants

2019 ◽  
Author(s):  
Silvia Melina Velasquez ◽  
Xiaoyuan Guo ◽  
Marçal Gallemi ◽  
Bibek Aryal ◽  
Peter Venhuizen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Growth Control ◽  
Size Control ◽  
Tissue Expansion ◽  
Central Importance ◽  
Hypocotyl Growth ◽  
Differential Growth ◽  
Rigid Cell Wall ◽  
Genetic Interference ◽  
Cell Wall Mechanics

Size control is a fundamental question in biology, showing incremental complexity in case of plants whose cells possess a rigid cell wall. The phytohormone auxin is a vital growth regulator with central importance for differential growth control. Here we show that growth inducing and repressing auxin conditions correlate with reduced and enhanced complexity of extracellular xyloglucans, respectively. In agreement, genetic interference with xyloglucan complexity distinctly modulates auxin-dependent differential growth rates. Our work proposes that an auxin-dependent, spatially defined effect on xyloglucan structure and its effect on cell wall mechanics specify differential, gravitropic hypocotyl growth.

scholarly journals Theory of branching morphogenesis by local interactions and global guidance

2021 ◽  
Author(s):  
Mehmet Can Uçar ◽  
Dmitrii Kamenev ◽  
Kazunori Sunadome ◽  
Dominik Fachet ◽  
François Lallemend ◽  
...  
Keyword(s):  
Scaling Law ◽  
Domain Size ◽  
Branching Morphogenesis ◽  
Tissue Growth ◽  
Regulatory Mechanisms ◽  
Local Interactions ◽  
Self Organized ◽  
Global Guidance ◽  
Different Types

Branching morphogenesis governs the formation of many organs such as lung, kidney, and the neurovascular system. Many studies have explored system-specific molecular and cellular regulatory mechanisms, as well as self-organizing rules underlying branching morphogenesis. However, in addition to local cues, branched tissue growth can also be influenced by global guidance. Here, we develop a theoretical framework for a stochastic self-organized branching process in the presence of external cues. Combining analytical theory with numerical simulations, we predict differential signatures of global vs. local regulatory mechanisms on the branching pattern, such as angle distributions, domain size, and space-filling efficiency. We find that branch alignment follows a generic scaling law determined by the strength of global guidance, while local interactions influence the tissue density but not its overall territory. Finally, using zebrafish innervation as a model system, we test these key features of the model experimentally. Our work thus provides quantitative predictions to disentangle the role of different types of cues in shaping branched structures across scales.

scholarly journals Amotl2a interacts with the Hippo effector Yap1 and the Wnt/β-catenin effector Lef1 to control tissue size in zebrafish

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Sobhika Agarwala ◽  
Sandra Duquesne ◽  
Kun Liu ◽  
Anton Boehm ◽  
Lin Grimm ◽  
...  
Keyword(s):  
Hippo Pathway ◽  
Growth Control ◽  
Tissue Growth ◽  
Cell Junction ◽  
Hippo Signaling ◽  
Sensory Organs ◽  
Hippo Signaling Pathway ◽  
Tissue Size ◽  
The Hippo Pathway ◽  
First Time

During development, proliferation must be tightly controlled for organs to reach their appropriate size. While the Hippo signaling pathway plays a major role in organ growth control, how it senses and responds to increased cell density is still unclear. In this study, we use the zebrafish lateral line primordium (LLP), a group of migrating epithelial cells that form sensory organs, to understand how tissue growth is controlled during organ formation. Loss of the cell junction-associated Motin protein Amotl2a leads to overproliferation and bigger LLP, affecting the final pattern of sensory organs. Amotl2a function in the LLP is mediated together by the Hippo pathway effector Yap1 and the Wnt/β-catenin effector Lef1. Our results implicate for the first time the Hippo pathway in size regulation in the LL system. We further provide evidence that the Hippo/Motin interaction is essential to limit tissue size during development.

Sign in / Sign up

Export Citation Format

Share Document