Abstract:The de novo formation of secretory lumens plays an important role during organogenesis. It involves the establishment of a cellular apical pole and the elongation of luminal cavities. The molecular parameters controlling cell polarization have been heavily scrutinized. In particular, signalling from the extracellular matrix (ECM) proved essential to the proper localization of the apical pole by directed protein transport. However, little is known about the regulation of the shape and the directional developmen… Show more
“…Thus, nature adopts an elegant way to establish radial or bilateral body symmetry: in the first step, the most perfect – spherical – symmetry is generated, and then it is “flawed” to create radial or bilateral symmetry. Interestingly, mechanical forces have recently been described as also guiding the first breaking of the spherical symmetry of cysts, a process which occurs in order to generate tubes, as observable during the development of biliary ducts in the liver [81, 82]. Fig.…”
Section: Mechanical Forces and Morphogenesismentioning
ᅟSymmetry is an eye-catching feature of animal body plans, yet its causes are not well enough understood. The evolution of animal form is mainly due to changes in gene regulatory networks (GRNs). Based on theoretical considerations regarding fundamental GRN properties, it has recently been proposed that the animal genome, on large time scales, should be regarded as a system which can construct both the main symmetries – radial and bilateral – simultaneously; and that the expression of any of these depends on functional constraints. Current theories explain biological symmetry as a pattern mostly determined by phylogenetic constraints, and more by chance than by necessity. In contrast to this conception, I suggest that physical effects, which in many cases act as proximate, direct, tissue-shaping factors during ontogenesis, are also the ultimate causes – i.e. the indirect factors which provide a selective advantage – of animal symmetry, from organs to body plan level patterns. In this respect, animal symmetry is a necessary product of evolution. This proposition offers a parsimonious view of symmetry as a basic feature of the animal body plan, suggesting that molecules and physical forces act in a beautiful harmony to create symmetrical structures, but that the concert itself is directed by the latter.ReviewersThis article was reviewed by Eugene Koonin, Zoltán Varga and Michaël Manuel.
“…Thus, nature adopts an elegant way to establish radial or bilateral body symmetry: in the first step, the most perfect – spherical – symmetry is generated, and then it is “flawed” to create radial or bilateral symmetry. Interestingly, mechanical forces have recently been described as also guiding the first breaking of the spherical symmetry of cysts, a process which occurs in order to generate tubes, as observable during the development of biliary ducts in the liver [81, 82]. Fig.…”
Section: Mechanical Forces and Morphogenesismentioning
ᅟSymmetry is an eye-catching feature of animal body plans, yet its causes are not well enough understood. The evolution of animal form is mainly due to changes in gene regulatory networks (GRNs). Based on theoretical considerations regarding fundamental GRN properties, it has recently been proposed that the animal genome, on large time scales, should be regarded as a system which can construct both the main symmetries – radial and bilateral – simultaneously; and that the expression of any of these depends on functional constraints. Current theories explain biological symmetry as a pattern mostly determined by phylogenetic constraints, and more by chance than by necessity. In contrast to this conception, I suggest that physical effects, which in many cases act as proximate, direct, tissue-shaping factors during ontogenesis, are also the ultimate causes – i.e. the indirect factors which provide a selective advantage – of animal symmetry, from organs to body plan level patterns. In this respect, animal symmetry is a necessary product of evolution. This proposition offers a parsimonious view of symmetry as a basic feature of the animal body plan, suggesting that molecules and physical forces act in a beautiful harmony to create symmetrical structures, but that the concert itself is directed by the latter.ReviewersThis article was reviewed by Eugene Koonin, Zoltán Varga and Michaël Manuel.
“…Coating pits with different proteins on their top, sides and bottom allows exquisite control over cell-cell interactions that are induced by matrix adhesion in 3D. This approach has been recently used to reveal how intercellular tension guides the luminogenesis in hepatocytes (Li et al, 2016). Embedding micromirrors in close vicinity to these micropits enables 3D super-resolution imaging of cells in their environment with a sectioning capability of up to tens of microns above the coverslip (Galland et al, 2015).…”
Section: Ecm Sensingmentioning
confidence: 99%
“…In this context, the mechanotransduction role of β1 and β3 integrins was singled out (Fourel et al, 2016;Schiller et al, 2013). In addition, 2D and 3D protein printing has demonstrated how the spatial structuration of the adhesive environment influences the localization (Rodríguez-Fraticelli et al, 2012) and shapes (Li et al, 2016) of apical lumens. Epithelial morphogenesis has also been found to depend on the biophysical properties of surrogate matrix gels (Enemchukwu et al, 2016).…”
Section: Ecm Sensingmentioning
confidence: 99%
“…Moreover, microwells can be used to structure the 3D spatial arrangement of cellular adhesion and to create bona fide cellular microniches ( Fig. 2A) (Charnley et al, 2012;Li et al, 2016). Substrates with gradients of adhesive properties (Fig.…”
Section: Brief Overview Over Bio-functionalized Substratesmentioning
Biomimetic materials have long been the (he)art of bioengineering. They usually aim at mimicking in vivo conditions to allow in vitro culture, differentiation and expansion of cells. The past decade has witnessed a considerable amount of progress in soft lithography, bioinspired micro-fabrication and biochemistry, allowing the design of sophisticated and physiologically relevant micro-and nanoenvironments. These systems now provide an exquisite toolbox with which we can control a large set of physicochemical environmental parameters that determine cell behavior. Biofunctionalized surfaces have evolved from simple protein-coated solid surfaces or cellular extracts into nano-textured 3D surfaces with controlled rheological and topographical properties. The mechanobiological molecular processes by which cells interact and sense their environment can now be unambiguously understood down to the single-molecule level. This Commentary highlights recent successful examples where bio-functionalized substrates have contributed in raising and answering new questions in the area of extracellular matrix sensing by cells, cell-cell adhesion and cell migration. The use, the availability, the impact and the challenges of such approaches in the field of biology are discussed.
“…Examples of these include secretory lumena in the liver [26], the tracheal lumen in Drosophila embryos [27], and lumena of blood vessels. In blood vessel tubulogenesis, cell-cell adhesions participate in establishing polarity and may also act as mechanosensors linking blood flow to vascular remodeling.…”
Section: Morphogenesis Of 3d Tissue Architecture In Vivomentioning
During tissue morphogenesis, cellular rearrangements give rise to a large variety of three-dimensional structures. Final tissue architecture varies greatly across organs, and many develop to include combinations of folds, tubes, and branched networks. To achieve these different tissue geometries, constituent cells must follow different programs that dictate changes in shape and/or migratory behavior. One essential component of these changes is the remodeling of cell-cell adhesions. Invasive migratory behavior and separation between tissues require localized breakdown of cadherin-mediated adhesions. Conversely, tissue folding and fusion require the formation and reinforcement of cell-cell adhesions. Cell-cell adhesion plays a critical role in tissue morphogenesis; its manipulation may therefore prove to be invaluable in generating complex topologies ex vivo. Recapitulating these shapes in engineered tissues would enable a better understanding of how these processes occur in vivo, and may lead to improved design of organs for clinical applications. In this review, we discuss work investigating the formation of folds, tubes, and branched networks with an emphasis on known or possible roles for cell-cell adhesion. We then examine recently developed tools that could be adapted to manipulate cell-cell adhesion in engineered tissues.
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