scholarly journals Bimodal Spindle Orientation Drives Tissue Regularity in a Proliferating Epithelium

2017 ◽  
Author(s):  
Tara M. Finegan ◽  
Daxiang Na ◽  
Austin V. Skeeters ◽  
Nicole S. Dawney ◽  
Patrick W. Oakes ◽  
...  
Keyword(s):  
Cell Shape ◽  
Tissue Expansion ◽  
Follicular Epithelium ◽  
Spindle Orientation ◽  
Epithelial Tissue ◽  
Interphase Cell ◽  
Cortical Tension ◽  
Geometric Packing ◽  
Summary Statement ◽  
The Relationship

AbstractWe investigated the relationship between proliferation and tissue topology in an epithelial tissue undergoing elongation. We found that cell division is not required for elongation of the early Drosophila follicular epithelium, but does drive the tissue towards optimal geometric packing. To increase tissue regularity, cell divisions are oriented in the planar axis, along the direction of tissue expansion. Planar division orientation is governed by apico-cortical tension, which aligns with tissue expansion but not with interphase cell shape elongation. Hertwig’s Rule, which holds that cell elongation determines division orientation, is therefore broken in this tissue. We tested whether this observation could be explained by anisotropic activity of the conserved Pins/Mud spindle-orienting machinery, which controls division orientation in the apical-basal axis. We found that Pins/Mud does not participate in planar division orientation. Rather, tension translates into planar division orientation in a manner dependent on Canoe/Afadin, which links actomyosin to adherens junctions. These findings demonstrate that division orientation in different axes - apical-basal and planar - is controlled by distinct, independent mechanisms in a proliferating epithelium.Summary StatementRegularity in a proliferating epithelium requires cells to divorce division orientation from interphase shape, which they accomplish by using distinct mechanisms to orient divisions in the apical-basal and planar axes.

scholarly journals Tissue tension and not interphase cell shape determines cell division orientation in the Drosophila follicular epithelium

2018 ◽  
Vol 38 (3) ◽  
Author(s):  
Tara M Finegan ◽  
Daxiang Na ◽  
Christian Cammarota ◽  
Austin V Skeeters ◽  
Tamás J Nádasi ◽  
...  
Keyword(s):  
Cell Division ◽  
Cell Shape ◽  
Follicular Epithelium ◽  
Interphase Cell ◽  
Tissue Tension

On the 3D Correlation between Myofibroblast Shape and Contraction

2021 ◽  
Author(s):  
Alex Khang ◽  
Emma Lejeune ◽  
Ali Abbaspour ◽  
Daniel Howsmon ◽  
Michael Sacks
Keyword(s):  
Cell Shape ◽  
Interstitial Cell ◽  
Stable State ◽  
Stress Fiber ◽  
Poly Ethylene Glycol ◽  
Critical Feature ◽  
Peg Hydrogels ◽  
Poly Ethylene ◽  
And Function ◽  
The Relationship

Abstract Cell shape is known to correlate closely with stress-fiber geometry and function, and is thus a critical feature of cell biophysical state. However, the relationship between myofibroblast shape and contraction is complex, even as well in regards to steady-state contractile level (basal tonus). At present, the relationship between myofibroblast shape and basal tonus in 3D is poorly understood. Herein, we utilize the aortic valve interstitial cell (AVICs) as a representative myofibroblast to investigate the relationship between basal tonus and overall cell shape. AVICs were embedded within 3D poly (ethylene glycol) (PEG) hydrogels containing degradable peptide crosslinkers, adhesive peptide sequences, and sub-micron fluorescent micro-spheres to track the local displacement field. We then developed a methodology to evaluate the correlation between overall AVIC shape and basal tonus induced contraction. We computed a volume averaged stretch tensor <U> for the volume occupied by the AVIC, which had three distinct eigenvalues (1.08, 0.99, and 0.89), suggesting that AVIC shape is a result of anisotropic contraction. Furthermore, the direction of maximum contraction correlated closely with the longest axis of a bounding ellipsoid enclosing the AVIC. As gel--imbedded AVIC are known to be in a stable state by three days of incubation used herein, this finding suggests that the overall quiescent AVIC shape is driven by the underlying stress-fiber directional structure and possibly contraction level.

The relationship between emerging neural crest cells and basement membranes in the trunk of the mouse embryo: a TEM and immunocytochemical study

Development ◽  
1986 ◽  
Vol 98 (1) ◽  
pp. 251-268
Author(s):  
J. Sternberg ◽  
S. J. Kimber
Keyword(s):  
Neural Crest ◽  
Neural Tube ◽  
Cell Shape ◽  
Type Iv Collagen ◽  
Neural Crest Cell ◽  
Basement Membranes ◽  
Type Iv ◽  
Transmission Electron ◽  
The Relationship ◽  
Crest Cell

The earliest stage of neural crest cell (NCC) migration is characterized by an epitheliomesenchymal transformation, as the cells leave the neural tube. There is evidence that in a number of cell systems this transformation is accompanied by alteration or depletion of associated basement membranes. This study examines the ultrastructural relationship between mouse NCCs and adjacent basement membranes during the earliest stages of migration from the neural tube. Basement membranes were identified by transmission electron microscopy (TEM) and immunofluorescence using antibodies to type-IV collagen. The ultrastructural features of NCCs and their relationship with surrounding tissues were also examined using TEM. In the dorsal region of the neural tube, from which NCCs originate, the basement membrane was depleted or absent, and with the immunofluorescence technique it was shown that this pattern was reflected in a deficit of type-IV collagen. TEM observations indicated that ultrastructurally NCCs differ from their neuroepithelial neighbours only in overall cell shape and their relationship to other cells and the extracellular matrix.

scholarly journals Cell shape and intercellular adhesion regulate mitotic spindle orientation

2019 ◽  
Vol 30 (19) ◽  
pp. 2458-2468 ◽  
Author(s):  
Jingchen Li ◽  
Longcan Cheng ◽  
Hongyuan Jiang
Keyword(s):  
Cell Division ◽  
Epithelial Cells ◽  
Cell Fate ◽  
Cell Shape ◽  
Intercellular Adhesion ◽  
Shape Anisotropy ◽  
Spindle Orientation ◽  
Mitotic Spindles ◽  
Strong Adhesion ◽  
Fate Decision

Cell division orientation plays an essential role in tissue morphogenesis and cell fate decision. Recent studies showed that either cell shape or adhesion geometry can regulate the orientation of mitotic spindles and thereby the cell division orientation. However, how they together regulate the spindle orientation remains largely unclear. In this work, we use a general computational model to investigate the competitive mechanism of determining the spindle orientation between cell shape and intercellular adhesion in epithelial cells. We find the spindle orientation is dominated by the intercellular adhesion when the cell shape anisotropy is small, but dominated by the cell shape when the shape anisotropy is large. A strong adhesion and moderate adhesive size can ensure the planar division of epithelial cells with large apico-basal elongation. We also find the spindle orientation could be perpendicular to the adhesive region when only one side of the cell is adhered to an E-cadherin–coated matrix. But after the cell is compressed, the spindle orientation is governed by the cell shape and the spindle will be parallel to the adhesive region when the cell shape anisotropy is large. Finally, we demonstrate the competition between cell shape and tricellular junctions can also effectively regulate the spindle orientation.

scholarly journals Cell shape impacts on the positioning of the mitotic spindle with respect to the substratum

2015 ◽  
Vol 26 (7) ◽  
pp. 1286-1295 ◽  
Author(s):  
Francisco Lázaro-Diéguez ◽  
Iaroslav Ispolatov ◽  
Anne Müsch
Keyword(s):  
Mitotic Spindle ◽  
Cell Shape ◽  
Spindle Assembly Checkpoint ◽  
Mdck Cells ◽  
Spindle Pole ◽  
Spindle Orientation ◽  
Cell Cortex ◽  
Spindle Positioning ◽  
Spindle Poles ◽  
Spindle Position

All known mechanisms of mitotic spindle orientation rely on astral microtubules. We report that even in the absence of astral microtubules, metaphase spindles in MDCK and HeLa cells are not randomly positioned along their x-z dimension, but preferentially adopt shallow β angles between spindle pole axis and substratum. The nonrandom spindle positioning is due to constraints imposed by the cell cortex in flat cells that drive spindles that are longer and/or wider than the cell's height into a tilted, quasidiagonal x-z position. In rounder cells, which are taller, fewer cortical constraints make the x-z spindle position more random. Reestablishment of astral microtubule–mediated forces align the spindle poles with cortical cues parallel to the substratum in all cells. However, in flat cells, they frequently cause spindle deformations. Similar deformations are apparent when confined spindles rotate from tilted to parallel positions while MDCK cells progress from prometaphase to metaphase. The spindle disruptions cause the engagement of the spindle assembly checkpoint. We propose that cell rounding serves to maintain spindle integrity during its positioning.

Shrinkage of Tracheid Cells With Desorption Visualized by Confocal Laser Scanning Microscopy

IAWA Journal ◽  
2007 ◽  
Vol 28 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Hiroki Sakagami ◽  
Junji Matsumura ◽  
Kazuyuki Oda
Keyword(s):  
Confocal Laser Scanning Microscopy ◽  
Cell Shape ◽  
Laser Scanning ◽  
Pinus Densiflora ◽  
Laser Scanning Microscopy ◽  
Confocal Laser Scanning ◽  
Scanning Microscopy ◽  
Confocal Laser ◽  
Environment Chamber ◽  
The Relationship

Confocal laser scanning microscopy (CLSM) was applied as a new method of visualizing the shrinkage of wood and its anisotropy. Control of relative humidity and temperature in a specialized environment chamber made it possible to acquire transverse images of tracheids of Akamatsu (Pinus densiflora) from the saturated condition to the dried condition. The shrinkage of tracheid cells was also determined by measuring the tangential diameter of tracheid and lumen, the radial diameter of tracheid and lumen, and the thickness of tangential and radial walls. Moreover, this technique makes it possible to discuss the relationship between moisture content and tracheid cell shape. We found the CLSM technique to be an effective method for visualizing shrinkage of tracheid cells with desorption.

scholarly journals Cdk1-dependent destabilization of long astral microtubules is required for spindle orientation

2020 ◽  
Author(s):  
Divya Singh ◽  
Nadine Schmidt ◽  
Franziska Müller ◽  
Tanja Bange ◽  
Alexander W. Bird
Keyword(s):  
Mitotic Spindle ◽  
Cell Shape ◽  
Microtubule Dynamics ◽  
Spindle Orientation ◽  
Cell Cortex ◽  
Spindle Positioning ◽  
Tissue Organization ◽  
Microtubule Stability ◽  
Astral Microtubule ◽  
Early Mitosis

AbstractThe precise execution of mitotic spindle orientation in response to cell shape cues is important for tissue organization and development. The presence of astral microtubules extending from the centrosome towards the cell cortex is essential for this process, but little is understood about the contribution of astral microtubule dynamics to spindle positioning, or how astral microtubule dynamics are regulated spatiotemporally. The mitotic regulator Cdk1-CyclinB promotes destabilization of centrosomal microtubules and increased microtubule dynamics as cells transition from interphase to mitosis, but how Cdk1 activity specifically modulates astral microtubule stability, and whether it impacts spindle positioning, is unknown. Here we uncover a mechanism revealing that Cdk1 destabilizes astral microtubules to ensure spindle reorientation in response to cell shape. Phosphorylation of the EB1-dependent microtubule plus-end tracking protein GTSE1 by Cdk1 in early mitosis abolishes its interaction with EB1 and recruitment to microtubule plus-ends. Loss of Cdk1 activity, or mutation of phosphorylation sites in GTSE1, induces recruitment of GTSE1 to growing microtubule plus-ends in mitosis. This decreases the catastrophe frequency of astral microtubules, and causes an increase in the number of long astral microtubules reaching the cell cortex, which restrains the ability of cells to reorient spindles along the long cellular axis in early mitosis. Astral microtubules must thus not only be present, but also dynamic to allow the spindle to reorient in response to cell shape, a state achieved by selective destabilization of long astral microtubules via Cdk1.

scholarly journals Adaptation of the Relationship in the "Parasite–Host" System with Parasitism Paramphistomum сervi in the Small Intestine of Sheeps

2020 ◽  
Vol 14 (1) ◽  
pp. 46-52
Author(s):  
Oksana I. Bibik ◽  
Ivan A. Arkhipov ◽  
Lyubov V. Nacheva ◽  
Miсhail S. Boborykin
Keyword(s):  
Small Intestine ◽  
Mucous Membrane ◽  
Microstructural Analysis ◽  
Epithelial Tissue ◽  
Host System ◽  
Mutual Relations ◽  
The Relationship ◽  
Histological Procedure ◽  
Histological Staining

The purpose of the research is studying microstructural changes in the process of adaptation of components during the formation of the “parasite–host” system by the example of Paramphistomum cervi (Zeder, 1790) parasitizing in the small intestine of spontaneously infected sheep. Materials and methods. Peculiarities of changes in the microstructure of the small intestine in the “parasite–host” system were studied using parasitization of P. cervi in the intestines of sheep using well-known histological methods. Pieces of tissue of the small intestine of sheep with P. cervi, after being preserved in 70% alcohol, were processed according to the generally accepted histological procedure and embedded in paraffin. Sections 5–7 μm in thickness were stained with histological stains and examined under a light microscope. Results and discussion. Microstructural analysis of the characteristics of the relationship in the "parasite–host" system showed that the mucous membrane of the small intestine of sheep in the presence of P. cervi looks sharply thickened. Swelling of the epithelium of villi and crypts, its vacuolization and albuminoid degeneration were found. In some places, proliferation of the epithelial layer of the mucous membrane was detected, due to which epithelial hyperplasia is observed, in some cases turning into metaplasia. Proliferation and hyperplasia (metaplasia) in the endostation of the host in the presence of the parasite contribute to: 1. stability of the parasite-host system and the participation of trematodes in trophism; 2. determination of the clinical and morphological picture of trematodose; 3. predicting the effects of this pathology on the host. Adhesion in the microstructural complex “trematode tegument – epithelial tissue of the villi of the small intestine” in ovine paramphistomosis at the contact level of two glycocalyx layers – the tegument of P. cervi and the surface of the epithelial cells of the villi of the host’s intestine, as well as single histological staining of the sites of contact between the parasite and the host as a result of mixing the components of the trematode tegument and the tissue of the host’s small intestine with deep adhesion indicate the established mutual relations between the components of a single system "parasite–host".

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