scholarly journals Epithelial invagination by vertical telescoping

2019 ◽  
Author(s):  
Jingjing Li ◽  
Andrew D. Economou ◽  
Jeremy B.A. Green

AbstractEpithelial bending is a fundamental process that shapes organs during development. All currently known mechanisms involve cells locally changing shape from columnar to wedge-shaped. Often this shape change occurs by cytoskeletal contraction at cell apices (“apical constriction”) but mechanisms such as basal nuclear positioning (“basal wedging”) or extrinsic compression are also known. Here we demonstrate a completely different mechanism which occurs without cell wedging. In mammalian salivary glands and teeth, we show that initial invagination occurs through coordinated vertical cell movement. Specifically, we show that cells towards the periphery of the placode move vertically upwards while their more central neighbours move downwards to create the invagination. We further show that this occurs by active cell-on-cell migration: outer cells migrate with an apical leading edge protrusion, depressing the central cells to “telescope” the epithelium downwards into the underlaying mesenchyme. Cells remain basally attached to the underlying lamina while their apical protrusions are dynamic and planar polarised centripetally. These protrusions depend on the actin cytoskeleton, and inhibition of the branching molecule Arp2/3 inhibits them and the invagination. FGF and Hedgehog morphogen signals are also required, with FGF providing a directional cue. These findings show that epithelial bending can be achieved by novel morphogenetic mechanism of coordinated cell rearrangement quite distinct from previously recognised invagination processes.

2006 ◽  
Vol 176 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Erik Sahai ◽  
Raquel Garcia-Medina ◽  
Jacques Pouysségur ◽  
Emmanuel Vial

Rho GTPases participate in various cellular processes, including normal and tumor cell migration. It has been reported that RhoA is targeted for degradation at the leading edge of migrating cells by the E3 ubiquitin ligase Smurf1, and that this is required for the formation of protrusions. We report that Smurf1-dependent RhoA degradation in tumor cells results in the down-regulation of Rho kinase (ROCK) activity and myosin light chain 2 (MLC2) phosphorylation at the cell periphery. The localized inhibition of contractile forces is necessary for the formation of lamellipodia and for tumor cell motility in 2D tissue culture assays. In 3D invasion assays, and in in vivo tumor cell migration, the inhibition of Smurf1 induces a mesenchymal–amoeboid–like transition that is associated with a more invasive phenotype. Our results suggest that Smurf1 is a pivotal regulator of tumor cell movement through its regulation of RhoA signaling.


2009 ◽  
Vol 296 (3) ◽  
pp. C414-C421 ◽  
Author(s):  
Shannon M. Gallagher ◽  
John J. Castorino ◽  
Nancy J. Philp

Monocarboxylate transporter (MCT) 4 is a heteromeric proton-coupled lactate transporter that is noncovalently linked to the extracellular matrix metalloproteinase inducer CD147 and is typically expressed in glycolytic tissues. There is increasing evidence to suggest that ion transporters are part of macromolecular complexes involved in regulating β1-integrin adhesion and cell movement. In the present study we examined whether MCTs play a role in cell migration through their interaction with β1-integrin. Using reciprocal coimmunoprecipitation assays, we found that β1-integrin selectively associated with MCT4 in ARPE-19 and MDCK cells, two epithelial cell lines that express both MCT1 and MCT4. In polarized monolayers of ARPE-19 cells, MCT4 and β1-integrin colocalized to the basolateral membrane, while both proteins were found in the leading edge lamellapodia of migrating cells. In scratch-wound assays, MCT4 knockdown slowed migration and increased focal adhesion size. In contrast, silencing MCT1 did not alter the rate of cell migration or focal adhesion size. Taken together, our findings suggest that the specific interaction of MCT4 with β1-integrin may regulate cell migration through modulation of focal adhesions.


2017 ◽  
Vol 28 (14) ◽  
pp. 1924-1936 ◽  
Author(s):  
Mary Katherine Connacher ◽  
Jian Wei Tay ◽  
Natalie G. Ahn

In contrast to events at the cell leading edge, rear-polarized mechanisms that control directional cell migration are poorly defined. Previous work described a new intracellular complex, the Wnt5a-receptor-actomyosin polarity (WRAMP) structure, which coordinates the polarized localization of MCAM, actin, and myosin IIB in a Wnt5a-induced manner. However, the polarity and function for the WRAMP structure during cell movement were not determined. Here we characterize WRAMP structures during extended cell migration using live-cell imaging. The results demonstrate that cells undergoing prolonged migration show WRAMP structures stably polarized at the rear, where they are strongly associated with enhanced speed and persistence of directional movement. Strikingly, WRAMP structures form transiently, with cells displaying directional persistence during periods when they are present and cells changing directions randomly when they are absent. Cells appear to pause locomotion when WRAMP structures disassemble and then migrate in new directions after reassembly at a different location, which forms the new rear. We conclude that WRAMP structures represent a rear-directed cellular mechanism to control directional migration and that their ability to form dynamically within cells may control changes in direction during extended migration.


2016 ◽  
Vol 7 (1) ◽  
Author(s):  
Thibault Courtheoux ◽  
Radoslav I. Enchev ◽  
Fabienne Lampert ◽  
Juan Gerez ◽  
Jochen Beck ◽  
...  

Abstract Directed cell movement involves spatial and temporal regulation of the cortical microtubule (Mt) and actin networks to allow focal adhesions (FAs) to assemble at the cell front and disassemble at the rear. Mts are known to associate with FAs, but the mechanisms coordinating their dynamic interactions remain unknown. Here we show that the CRL3KLHL21 E3 ubiquitin ligase promotes cell migration by controlling Mt and FA dynamics at the cell cortex. Indeed, KLHL21 localizes to FA structures preferentially at the leading edge, and in complex with Cul3, ubiquitylates EB1 within its microtubule-interacting CH-domain. Cells lacking CRL3KLHL21 activity or expressing a non-ubiquitylatable EB1 mutant protein are unable to migrate and exhibit strong defects in FA dynamics, lamellipodia formation and cortical plasticity. Our study thus reveals an important mechanism to regulate cortical dynamics during cell migration that involves ubiquitylation of EB1 at focal adhesions.


2005 ◽  
Vol 280 (23) ◽  
pp. 21748-21755 ◽  
Author(s):  
Khalid Sossey-Alaoui ◽  
Xiurong Li ◽  
Tamara A. Ranalli ◽  
John K. Cowell

WAVE3 is a member of the WASP/WAVE family of protein effectors of actin reorganization and cell movement. The precise role of WAVE3 in cell migration and its regulation, however, have not been elucidated. Here we show that endogenous WAVE3 was found to be concentrated in the lamellipodia at the leading edge of migrating MDA-MB-231 cells. Platelet-derived growth factor (PDGF) treatment induced lamellipodia formation as well as two-dimensional migration of cells in the wound-closure assay and chemotactic migration toward PDGF in three-dimensional migration chambers. Knockdown of WAVE3 expression by RNA interference prevented the PDGF-induced lamellipodia formation and cell migration. Treatment of cells with LY294002, an inhibitor of phosphatidylinositol 3-kinase (PI3K), also abrogated the PDGF-induced lamellipodia formation and cell migration, suggesting that PI3K may be required for WAVE3 activity. WAVE3 and the PI3K regulatory subunit, p85, were found to interact in a yeast two-hybrid screen, which was confirmed through co-immunoprecipitation. The WAVE3-p85 interaction was mediated by the N-terminal region of WAVE3 and the C-terminal SH2 domain of p85. These results imply that the WAVE3-mediated migration in MDA-MB-231 cells via lamellipodia formation is activated downstream of PI3K and induced by PDGF. The findings of the WAVE3-p85 partnership also suggest a potential regulatory role for p85 in WAVE3-dependent actin-cytoskeleton reorganization and cell migration.


2005 ◽  
Vol 171 (2) ◽  
pp. 349-359 ◽  
Author(s):  
Michiru Nishita ◽  
Chinatsu Tomizawa ◽  
Masahiro Yamamoto ◽  
Yuji Horita ◽  
Kazumasa Ohashi ◽  
...  

Cofilin mediates lamellipodium extension and polarized cell migration by accelerating actin filament dynamics at the leading edge of migrating cells. Cofilin is inactivated by LIM kinase (LIMK)–1-mediated phosphorylation and is reactivated by cofilin phosphatase Slingshot (SSH)-1L. In this study, we show that cofilin activity is temporally and spatially regulated by LIMK1 and SSH1L in chemokine-stimulated Jurkat T cells. The knockdown of LIMK1 suppressed chemokine-induced lamellipodium formation and cell migration, whereas SSH1L knockdown produced and retained multiple lamellipodial protrusions around the cell after cell stimulation and impaired directional cell migration. Our results indicate that LIMK1 is required for cell migration by stimulating lamellipodium formation in the initial stages of cell response and that SSH1L is crucially involved in directional cell migration by restricting the membrane protrusion to one direction and locally stimulating cofilin activity in the lamellipodium in the front of the migrating cell. We propose that LIMK1- and SSH1L-mediated spatiotemporal regulation of cofilin activity is critical for chemokine-induced polarized lamellipodium formation and directional cell movement.


2020 ◽  
Author(s):  
Joseph H.R. Hetmanski ◽  
Matt Jones ◽  
Fatima Chunara ◽  
Jean-Marc Schwartz ◽  
Patrick T. Caswell

AbstractCell migration in 3D micro-environments is a complex process which depends on the coordinated activity of leading edge protrusive force and rear retraction in a push-pull mechanism. While the potentiation of protrusions has been widely studied, the precise signalling and mechanical events that lead to forward movement of the cell rear are much less well understood, particularly in physiological 3D extra-cellular matrix (ECM). We previously discovered that rear retraction in fast moving cells is a highly dynamic process involving the precise spatiotemporal interplay of mechanosensing by caveolae and signalling through RhoA. To further interrogate the dynamics of rear retraction, we have adopted three distinct mathematical modelling approaches here based on (i) Boolean logic, (ii) deterministic kinetic ordinary differential equations (ODEs) and (iii) stochastic simulations. The aims of this multi-faceted approach are twofold: firstly to derive new biological insight into cell rear dynamics via generation of testable hypotheses and predictions; and secondly to compare and contrast the distinct modelling approaches when used to describe the same, relatively under-studied system. Whilst Boolean logic was not able to fully recapitulate the complexity of rear retraction signalling completely, our ODE model could make plausible population level predictions. Stochastic simulations added a further level of complexity by accurately mimicking previous experimental findings and acting as a single cell simulator. Our approach has also highlighted the unanticipated potential of targeting CDK1 to abrogate cell movement, a prediction we confirmed experimentally. Moreover, we have made a novel prediction regarding the potential existence of a ‘set point’ in local stiffness gradients that promotes polarisation and rapid rear retraction. Overall, our modelling approaches complement each other, suggesting that such a multi-faceted approach is more informative than methods based on a single modelling technique to interrogate biological systems.


2019 ◽  
Vol 63 (5) ◽  
pp. 579-594 ◽  
Author(s):  
Guillem Lambies ◽  
Antonio García de Herreros ◽  
Víctor M. Díaz

Abstract Cell migration is a multifactorial/multistep process that requires the concerted action of growth and transcriptional factors, motor proteins, extracellular matrix remodeling and proteases. In this review, we focus on the role of transcription factors modulating Epithelial-to-Mesenchymal Transition (EMT-TFs), a fundamental process supporting both physiological and pathological cell migration. These EMT-TFs (Snail1/2, Twist1/2 and Zeb1/2) are labile proteins which should be stabilized to initiate EMT and provide full migratory and invasive properties. We present here a family of enzymes, the deubiquitinases (DUBs) which have a crucial role in counteracting polyubiquitination and proteasomal degradation of EMT-TFs after their induction by TGFβ, inflammatory cytokines and hypoxia. We also describe the DUBs promoting the stabilization of Smads, TGFβ receptors and other key proteins involved in transduction pathways controlling EMT.


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