Quantification of skeletal muscle functional contraction is essential to assess the outcomes of therapeutic pro-cedures for neuromuscular disorders. Muscle three-dimensional "Organ-on-chip" models usually require a sub-stantial amount of biological material, which rarely can be obtained from patient biopsies. Here, we developed a miniaturized 3D myotube culture chip with contraction monitoring capacity at the single cell level. Optimized micropatterned substrate design enabled to obtain high culture yields in tightly controlled microenvironments, with myotubes derived from primary human myoblasts displaying spontaneous contractions. Analysis of nuclear morphology confirmed similar myonuclei structure between obtained myotubes and in vivo myofibers, as compared to 2D monolayers. LMNA-related Congenital Muscular Dystrophy (L-CMD) was modeled with suc-cessful development of diseased 3D myotubes displaying reduced contraction. The miniaturized myotube tech-nology can thus be used to study contraction characteristics and evaluate how diseases affect muscle organization and force generation. Importantly, it requires significantly fewer starting materials than current systems, which should substantially improve drug screening capability.
Cells, the "Little Thumbs" of living tissue
Joseph d'Alessandro,
Alex Barbier-Chebbah,
Raphael Voituriez,
Benoit Ladoux
M S-Medecine Sciences
38
(11)
861-863
(2022)
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Mechanical stress driven by rigidity sensing governs epithelial stability
Surabhi Sonam,
Lakshmi Balasubramaniam,
Shao-Zhen Lin,
Ying Ming Yow Ivan,
Irina Pi-Jauma,
Cecile Jebane,
Marc Karnat,
Yusuke Toyama,
Philippe Marcq, et al.
Epithelia act as barriers against environmental stresses. They are continuously exposed to various mechanical stress and abrasion, which impact epithelial integrity. The impact of the environment on epithelial integrity remains elusive. By culturing epithelial cells on two-dimensional hydrogels, we observe a loss of epithelial monolayer integrity on soft substrates through spontaneous hole formation. These monolayer ruptures are associated with local cellular stretching and cell-division events. Substrate stiffness triggers an unanticipated mechanical switch of epithelial monolayers from compressive stress on stiff substrates to highly tensile on soft, favouring hole formation. In agreement with an active nematic model, hole-opening events occur preferentially near spontaneous half-integer topological defects, which underpin large isotropic stress fluctuations triggering stochastic mechanical failure. Our results thus show that substrate stiffness provides feedback on the mechanical state of epithelial monolayers with potential application towards a mechanistic understanding of compromised epithelial integrity during normal and pathological human ontogenesis.<br> On soft substrates, epithelial tissues are under high tension and form holes that spontaneously heal. Thus, mechanical stress directly impacts the integrity of epithelia.
Tissue mechanics
Alexandre Kabla,
Benoit Ladoux,
Jean-Marc Di Meglio
European Physical Journal E
45
(11)
90
(2022)
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Optineurin links Hace1-dependent Rac ubiquitylation to integrin-mediated mechanotransduction to control bacterial invasion and cell division
Serena Petracchini,
Daniel Hamaoui,
Anne Doye,
Atef Asnacios,
Florian Fage,
Elisa Vitiello,
Martial Balland,
Sebastien Janel,
Frank Lafont, et al.
Nature Communications
13
(1)
6059
(2022)
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Extracellular matrix (ECM) elasticity is perceived by cells via focal adhesion structures, which transduce mechanical cues into chemical signalling to conform cell behavior. Although the contribution of ECM compliance to the control of cell migration or division is extensively studied, little is reported regarding infectious processes. We study this phenomenon with the extraintestinal Escherichia coli pathogen UTI89. We show that UTI89 takes advantage, via its CNF1 toxin, of integrin mechanoactivation to trigger its invasion into cells. We identify the HACE1 E3 ligase-interacting protein Optineurin (OPTN) as a protein regulated by ECM stiffness. Functional analysis establishes a role of OPTN in bacterial invasion and integrin mechanical coupling and for stimulation of HACE1 E3 ligase activity towards the Rac1 GTPase. Consistent with a role of OPTN in cell mechanics, OPTN knockdown cells display defective integrin-mediated traction force buildup, associated with limited cellular invasion by UTI89. Nevertheless, OPTN knockdown cells display strong mechanochemical adhesion signalling, enhanced Rac1 activation and increased cyclin D1 translation, together with enhanced cell proliferation independent of ECM stiffness. Together, our data ascribe a new function to OPTN in mechanobiology.<br> Uropathogenic strains of Escherichia coli (UPEC) are a leading cause of urinary tract infections (UTIs) and invasion involves Rho GTPase members, notably Rac1, to drive actin cytoskeleton rearrangement leading to engulfment. Here, Petracchini et al. provide evidence of an ECM stiffnessmodulated role of Optineurin (OPTN), which regulates HACE1-dependant Rac1 activity and thus controls integrinmediated mechanotransduction and bacterial invasion.
The emergence of spontaneous coordinated epithelial rotation on cylindrical curved surfaces
Alexandros Glentis,
Carles Blanch-Mercader,
Lakshmi Balasubramaniam,
Thuan Beng Saw,
Joseph d'Alessandro,
Sebastien Janel,
Audrey Douanier,
Benedicte Delaval,
Frank Lafont, et al.
Science Advances
8
(37)
eabn5406
(2022)
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Three-dimensional collective epithelial rotation around a given axis represents a coordinated cellular movement driving tissue morphogenesis and transformation. Questions regarding these behaviors and their relationship with substrate curvatures are intimately linked to spontaneous active matter processes and to vital morpho-genetic and embryonic processes. Here, using interdisciplinary approaches, we study the dynamics of epithelial layers lining different cylindrical surfaces. We observe large-scale, persistent, and circumferential rotation in both concavely and convexly curved cylindrical tissues. While epithelia of inverse curvature show an orthogonal switch in actomyosin network orientation and opposite apicobasal polarities, their rotational movements emerge and vary similarly within a common curvature window. We further reveal that this persisting rotation requires stable cell-cell adhesion and Rac-1-dependent cell polarity. Using an active polar gel model, we unveil the different relationships of collective cell polarity and actin alignment with curvatures, which lead to coordinated rotational behavior despite the inverted curvature and cytoskeleton order. Commons NonCommercial License
Local contractions regulate E-cadherin rigidity sensing
Yi-An Yang,
Emmanuelle Nguyen,
Gautham Hari Narayana Sankara Narayana,
Melina Heuze,
Chaoyu Fu,
Hanry Yu,
Rene-Marc Mege,
Benoit Ladoux,
Michael P. Sheetz
E-cadherin is a major cell-cell adhesion molecule involved in mechanotransduction at cell-cell contacts in tissues. Because epithelial cells respond to rigidity and tension in tissue through E-cadherin, there must be active processes that test and respond to the mechanical properties of these adhesive contacts. Using submicrometer, E-cadherincoated polydimethylsiloxane pillars, we find that cells generate local contractions between E-cadherin adhesions and pull to a constant distance for a constant duration, irrespective of pillar rigidity. These cadherin contractions require nonmuscle myosin IIB, tropomyosin 2.1, alpha-catenin, and binding of vinculin to.-catenin. Cells spread to different areas on soft and rigid surfaces with contractions, but spread equally on soft and rigid without. We further observe that cadherin contractions enable cells to test myosin IIA-mediated tension of neighboring cells and sort out myosin IIA-depleted cells. Thus, we suggest that epithelial cells test and respond to the mechanical characteristics of neighboring cells through cadherin contractions.
Active nematics across scales from cytoskeleton organization to tissue morphogenesis
Current Opinion in Genetics & Development
73
101897
(2022)
| Journal
Biological tissues are composed of various cell types working cooperatively to perform their respective function within organs and the whole body. During development, embryogenesis followed by histogenesis relies on orchestrated division, death, differentiation and collective movements of cellular constituents. These cells are anchored to each other and/or the underlying substrate through adhesion complexes and they regulate force generation by active cytoskeleton remodelling. The resulting contractility related changes at the level of each single cell impact tissue architecture by triggering changes in cell shape, cell movement and remodelling of the surrounding environment. These out of equilibrium processes occur through the consumption of energy, allowing biological systems to be described by active matter physics. 'Active nematics' a subclass of active matter encompasses cytoskeleton filaments, bacterial and eukaryotic cells allowing them to be modelled as rod-like elements to which nematic liquid crystal theories can be applied. In this review, we will discuss the concept of active nematics to understand biological processes across subcellular and multicellular scales, from single cell organization to cell extrusion, collective cell movements, differentiation and morphogenesis.
Contact
Tissue Mechanobiology Division Prof. Benoît Ladoux Principal Investigator
Max-Planck-Zentrum für Physik und Medizin Kussmaulallee 2 91054 Erlangen, Germany
