scholarly journals Microtubules promote intercellular contractile force transmission during tissue folding

2019 ◽  
Vol 218 (8) ◽  
pp. 2726-2742 ◽  
Author(s):  
Clint S. Ko ◽  
Vardges Tserunyan ◽  
Adam C. Martin
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Shape ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Contractile Force ◽  
Force Transmission ◽  
Microtubule Network ◽  
Apical Constriction ◽  
Actomyosin Contractility ◽  
Actomyosin Contraction

During development, forces transmitted between cells are critical for sculpting epithelial tissues. Actomyosin contractility in the middle of the cell apex (medioapical) can change cell shape (e.g., apical constriction) but can also result in force transmission between cells via attachments to adherens junctions. How actomyosin networks maintain attachments to adherens junctions under tension is poorly understood. Here, we discovered that microtubules promote actomyosin intercellular attachments in epithelia during Drosophila melanogaster mesoderm invagination. First, we used live imaging to show a novel arrangement of the microtubule cytoskeleton during apical constriction: medioapical Patronin (CAMSAP) foci formed by actomyosin contraction organized an apical noncentrosomal microtubule network. Microtubules were required for mesoderm invagination but were not necessary for initiating apical contractility or adherens junction assembly. Instead, microtubules promoted connections between medioapical actomyosin and adherens junctions. These results delineate a role for coordination between actin and microtubule cytoskeletal systems in intercellular force transmission during tissue morphogenesis.

scholarly journals Microtubules stabilize intercellular contractile force transmission during tissue folding

2019 ◽  
Author(s):  
Clint S. Ko ◽  
Vardges Tserunyan ◽  
Adam C. Martin
Keyword(s):  
Cell Shape ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Contractile Force ◽  
Force Transmission ◽  
Microtubule Network ◽  
Apical Constriction ◽  
Actomyosin Contractility ◽  
Actomyosin Contraction ◽  
Stable Connection

AbstractDuring development, forces transmitted between cells are critical for sculpting epithelial tissues. Actomyosin contractility in the middle of the cell apex (medioapical) can change cell shape (e.g., apical constriction), but can also result in force transmission between cells via attachments to adherens junctions. How actomyosin networks maintain attachments to adherens junctions under tension is poorly understood. Here, we discovered that microtubules stabilize actomyosin intercellular attachments in epithelia during Drosophila mesoderm invagination. First, we used live imaging to show a novel arrangement of the microtubule cytoskeleton during apical constriction: medioapical, non-centrosomal Patronin (CAMSAP) foci formed by actomyosin contraction organizes an apical microtubule network. Microtubules were required for mesoderm invagination but were not necessary for apical contractility or adherens junction assembly. Instead, microtubules promoted the stable connection between medioapical actomyosin and adherens junctions. These results define a role for coordination between actin and microtubule cytoskeletal systems in intercellular force transmission and tissue morphogenesis.

scholarly journals The Drosophila afadin homologue Canoe regulates linkage of the actin cytoskeleton to adherens junctions during apical constriction

2009 ◽  
Vol 186 (1) ◽  
pp. 57-73 ◽  
Author(s):  
Jessica K. Sawyer ◽  
Nathan J. Harris ◽  
Kevin C. Slep ◽  
Ulrike Gaul ◽  
Mark Peifer
Keyword(s):  
Actin Cytoskeleton ◽  
Cell Shape ◽  
Shape Change ◽  
Adherens Junctions ◽  
Apical Constriction ◽  
Cell Shape Change ◽  
Mediate Cell Adhesion ◽  
Mediate Cell ◽  
Actomyosin Cytoskeleton ◽  
Core Part

Cadherin-based adherens junctions (AJs) mediate cell adhesion and regulate cell shape change. The nectin–afadin complex also localizes to AJs and links to the cytoskeleton. Mammalian afadin has been suggested to be essential for adhesion and polarity establishment, but its mechanism of action is unclear. In contrast, Drosophila melanogaster’s afadin homologue Canoe (Cno) has suggested roles in signal transduction during morphogenesis. We completely removed Cno from embryos, testing these hypotheses. Surprisingly, Cno is not essential for AJ assembly or for AJ maintenance in many tissues. However, morphogenesis is impaired from the start. Apical constriction of mesodermal cells initiates but is not completed. The actomyosin cytoskeleton disconnects from AJs, uncoupling actomyosin constriction and cell shape change. Cno has multiple direct interactions with AJ proteins, but is not a core part of the cadherin–catenin complex. Instead, Cno localizes to AJs by a Rap1- and actin-dependent mechanism. These data suggest that Cno regulates linkage between AJs and the actin cytoskeleton during morphogenesis.

scholarly journals Integration of contractile forces during tissue invagination

2010 ◽  
Vol 188 (5) ◽  
pp. 735-749 ◽  
Author(s):  
Adam C. Martin ◽  
Michael Gelbart ◽  
Rodrigo Fernandez-Gonzalez ◽  
Matthias Kaschube ◽  
Eric F. Wieschaus
Keyword(s):  
Cell Shape ◽  
Control Cell ◽  
Adherens Junction ◽  
Tissue Level ◽  
Epithelial Morphogenesis ◽  
Apical Constriction ◽  
Contractile Forces ◽  
Actomyosin Cytoskeleton ◽  
Cellular Forces ◽  
Anterior Posterior

Contractile forces generated by the actomyosin cytoskeleton within individual cells collectively generate tissue-level force during epithelial morphogenesis. During Drosophila mesoderm invagination, pulsed actomyosin meshwork contractions and a ratchet-like stabilization of cell shape drive apical constriction. Here, we investigate how contractile forces are integrated across the tissue. Reducing adherens junction (AJ) levels or ablating actomyosin meshworks causes tissue-wide epithelial tears, which release tension that is predominantly oriented along the anterior–posterior (a-p) embryonic axis. Epithelial tears allow cells normally elongated along the a-p axis to constrict isotropically, which suggests that apical constriction generates anisotropic epithelial tension that feeds back to control cell shape. Epithelial tension requires the transcription factor Twist, which stabilizes apical myosin II, promoting the formation of a supracellular actomyosin meshwork in which radial actomyosin fibers are joined end-to-end at spot AJs. Thus, pulsed actomyosin contractions require a supracellular, tensile meshwork to transmit cellular forces to the tissue level during morphogenesis.

scholarly journals The adherens junction–associated LIM domain protein Smallish regulates epithelial morphogenesis

2018 ◽  
Vol 217 (3) ◽  
pp. 1079-1095 ◽  
Author(s):  
Hamze Beati ◽  
Irina Peek ◽  
Paulina Hordowska ◽  
Mona Honemann-Capito ◽  
Jade Glashauser ◽  
...  
Keyword(s):  
Planar Cell Polarity ◽  
Adherens Junction ◽  
Epithelial Morphogenesis ◽  
Lim Domain ◽  
Core Component ◽  
Apical Constriction ◽  
Binding Partner ◽  
Actomyosin Contractility ◽  
Lim Domain Protein ◽  
Embryonic Morphogenesis

In epithelia, cells adhere to each other in a dynamic fashion, allowing the cells to change their shape and move along each other during morphogenesis. The regulation of adhesion occurs at the belt-shaped adherens junction, the zonula adherens (ZA). Formation of the ZA depends on components of the Par–atypical PKC (Par-aPKC) complex of polarity regulators. We have identified the Lin11, Isl-1, Mec-3 (LIM) protein Smallish (Smash), the orthologue of vertebrate LMO7, as a binding partner of Bazooka/Par-3 (Baz), a core component of the Par-aPKC complex. Smash also binds to Canoe/Afadin and the tyrosine kinase Src42A and localizes to the ZA in a planar polarized fashion. Animals lacking Smash show loss of planar cell polarity (PCP) in the embryonic epidermis and reduced cell bond tension, leading to severe defects during embryonic morphogenesis of epithelial tissues and organs. Overexpression of Smash causes apical constriction of epithelial cells. We propose that Smash is a key regulator of morphogenesis coordinating PCP and actomyosin contractility at the ZA.

scholarly journals Regulation of tensile stress in response to external forces coordinates epithelial cell shape transitions with organ growth and elongation

2018 ◽  
Author(s):  
Ramya Balaji ◽  
Vanessa Weichselberger ◽  
Anne-Kathrin Classen
Keyword(s):  
Epithelial Cell ◽  
Cell Shape ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Apical Surface ◽  
Nurse Cells ◽  
Cuboidal Cell ◽  
Cell Shapes ◽  
External Forces ◽  
Shape Transitions

AbstractThe role of actomyosin contractility at epithelial adherens junctions has been extensively studied. However, little is known about how external forces are integrated to establish epithelial cell and organ shape in vivo. We use the Drosophila follicle epithelium to investigate how tension at adherens junctions is regulated to integrate external forces arising from changes in germline size and shape. We find that overall tension in the epithelium decreases despite pronounced growth of enclosed germline cells, suggesting that the epithelium relaxes to accommodate growth. However, we find local differences in adherens junction tension correlate with apposition to germline nurse cells or the oocyte. We demonstrate that medial Myosin II coupled to corrugating adherens junctions resists nurse cell-derived forces and thus maintains apical surface areas and cuboidal cell shapes. Furthermore, medial reinforcement of the apical surface ensures cuboidal-to-columnar cell shape transitions and imposes circumferential constraints on nurse cells guiding organ elongation. Our study provides insight into how tension within an adherens junction network integrates growth of a neighbouring tissue, mediates cell shape transitions and channels growth into organ elongation.

Real-time imaging of cell-cell adherens junctions reveals that Drosophila mesoderm invagination begins with two phases of apical constriction of cells

2001 ◽  
Vol 114 (3) ◽  
pp. 493-501 ◽  
Author(s):  
H. Oda ◽  
S. Tsukita
Keyword(s):  
Real Time ◽  
Cell Shape ◽  
Adherens Junctions ◽  
Cell Sheet ◽  
Apical Surface ◽  
Apical Constriction ◽  
Real Time Imaging ◽  
Cell Shape Changes ◽  
Shape Changes ◽  
Cell Cell

Invagination of the epithelial cell sheet of the prospective mesoderm in Drosophila gastrulation is a well-studied, relatively simple morphogenetic event that results from dynamic cell shape changes and cell movements. However, these cell behaviors have not been followed at a sufficiently short time resolution. We examined mesoderm invagination in living wild-type embryos by real-time imaging of fluorescently labeled cell-cell adherens junctions, which are located at the apical zones of cell-cell contact. Low-light fluorescence video microscopy directly visualized the onset and progression of invagination. In an initial period of approximately 2 minutes, cells around the ventral midline reduced their apical surface areas slowly in a rather synchronous manner. Next, the central and more lateral cells stochastically accelerated or initiated their apical constriction, giving rise to random arrangements of cells with small and relatively large apices. Thus, we found that mesoderm invagination began with slow synchronous and subsequent fast stochastic phases of cell apex constriction. Furthermore, we showed that the mesoderm invagination of folded gastrulation mutant embryos lacked the normal two constriction phases, and instead began with asynchronous, feeble cell shape changes. Our observations suggested that Folded gastrulation-mediated signaling enabled synchronous activation of the contractile cortex, causing competition among the individual mesodermal cells for apical constriction. Movies available on-line: http://www.biologists.com/JCS/movies/jcs2073.html

scholarly journals Independent cadherin–catenin and Bazooka clusters interact to assemble adherens junctions

2009 ◽  
Vol 185 (5) ◽  
pp. 787-796 ◽  
Author(s):  
Melanie A. McGill ◽  
R.F. Andrew McKinley ◽  
Tony J.C. Harris
Keyword(s):  
Drosophila Melanogaster ◽  
Fluorescence Recovery After Photobleaching ◽  
Molecular Level ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Drosophila Embryo ◽  
Fluorescence Recovery ◽  
Early Drosophila Embryo ◽  
Epithelial Structure ◽  
Independent Protein

Proper epithelial structure requires adherens junction (AJ) assembly. In the early Drosophila embryo, AJ assembly depends on Bazooka (Baz; PAR-3), but it is unclear how Baz affects AJ assembly and what precursors are involved. To understand this process at the molecular level, we counted the number of core AJ proteins and Baz proteins at an average spot AJ (SAJ) and determined their dynamics with fluorescence recovery after photobleaching experiments. These data reveal that SAJs are subdivided into Baz clusters and cadherin–catenin clusters with independent protein numbers and dynamics. This independence suggests that precursory cadherin–catenin clusters might form before SAJ assembly. We identify cadherin–catenin clusters forming between apical microvilli. Further analyses show that they form independently of Baz and that Baz functions in repositioning them to apicolateral sites for full SAJ assembly. Our data implicate cell protrusions in initial cadherin–catenin clustering in the Drosophila melanogaster embryo. Then, independent Baz clusters appear to engage the cadherin–catenin clusters to assemble SAJs.

scholarly journals Abl suppresses cell extrusion and intercalation during epithelium folding

2016 ◽  
Vol 27 (18) ◽  
pp. 2822-2832 ◽  
Author(s):  
Jeanne N. Jodoin ◽  
Adam C. Martin
Keyword(s):  
Cell Shape ◽  
Epithelial To Mesenchymal Transition ◽  
Adherens Junction ◽  
Apical Constriction ◽  
Mesenchymal Transition ◽  
Abl Tyrosine Kinase ◽  
Cell Intercalation ◽  
Shape Changes ◽  
Insight Into ◽  
Cell Extrusion

Tissue morphogenesis requires control over cell shape changes and rearrangements. In the Drosophila mesoderm, linked epithelial cells apically constrict, without cell extrusion or intercalation, to fold the epithelium into a tube that will then undergo epithelial-to-mesenchymal transition (EMT). Apical constriction drives tissue folding or cell extrusion in different contexts, but the mechanisms that dictate the specific outcomes are poorly understood. Using live imaging, we found that Abelson (Abl) tyrosine kinase depletion causes apically constricting cells to undergo aberrant basal cell extrusion and cell intercalation. abl depletion disrupted apical–basal polarity and adherens junction organization in mesoderm cells, suggesting that extruding cells undergo premature EMT. The polarity loss was associated with abnormal basolateral contractile actomyosin and Enabled (Ena) accumulation. Depletion of the Abl effector Enabled (Ena) in abl-depleted embryos suppressed the abl phenotype, consistent with cell extrusion resulting from misregulated ena. Our work provides new insight into how Abl loss and Ena misregulation promote cell extrusion and EMT.

scholarly journals Plasma membrane phosphoinositide balance regulates cell shape during Drosophila embryo morphogenesis

2014 ◽  
Vol 205 (3) ◽  
pp. 395-408 ◽  
Author(s):  
Alessandra Reversi ◽  
Eva Loeser ◽  
Devaraj Subramanian ◽  
Carsten Schultz ◽  
Stefano De Renzis
Keyword(s):  
Plasma Membrane ◽  
Cell Shape ◽  
Membrane Lipid ◽  
Drosophila Embryo ◽  
Membrane Domains ◽  
Membrane Lipid Composition ◽  
Actomyosin Contractility ◽  
Plasma Membrane Lipid ◽  
Zygotic Gene ◽  
Actomyosin Contraction

Remodeling of cell shape during morphogenesis is driven by the coordinated expansion and contraction of specific plasma membrane domains. Loss of this coordination results in abnormal cell shape and embryonic lethality. Here, we show that plasma membrane lipid composition plays a key role in coordinating plasma membrane contraction during expansion. We found that an increase in PI(4,5)P2 levels caused premature actomyosin contraction, resulting in the formation of shortened cells. Conversely, acute depletion of PI(4,5)P2 blocked plasma membrane expansion and led to premature actomyosin disassembly. PI(4,5)P2-mediated contractility is counteracted by PI(3,4,5)P3 and the zygotic gene bottleneck, which acts by limiting myosin recruitment during plasma membrane expansion. Collectively, these data support a model in which the ratio of PI(4,5)P2/PI(3,4,5)P3 coordinates actomyosin contractility and plasma membrane expansion during tissue morphogenesis, thus ensuring proper cell shape.

Sign in / Sign up

Export Citation Format

Share Document