scholarly journals Dynamics of adherens junctions in epithelial establishment, maintenance, and remodeling

2011 ◽  
Vol 192 (6) ◽  
pp. 907-917 ◽  
Author(s):  
Buzz Baum ◽  
Marios Georgiou
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Adherens Junction ◽  
Dynamic Structure ◽  
Rho Family Gtpases ◽  
Junction Formation ◽  
Rho Family ◽  
And Function ◽  
Adhesive Contacts ◽  
E Cadherin

The epithelial cadherin (E-cadherin)–catenin complex binds to cytoskeletal components and regulatory and signaling molecules to form a mature adherens junction (AJ). This dynamic structure physically connects neighboring epithelial cells, couples intercellular adhesive contacts to the cytoskeleton, and helps define each cell’s apical–basal axis. Together these activities coordinate the form, polarity, and function of all cells in an epithelium. Several molecules regulate AJ formation and integrity, including Rho family GTPases and Par polarity proteins. However, only recently, with the development of live-cell imaging, has the extent to which E-cadherin is actively turned over at junctions begun to be appreciated. This turnover contributes to junction formation and to the maintenance of epithelial integrity during tissue homeostasis and remodeling.

scholarly journals Biochemical and structural analysis of α-catenin in cell–cell contacts

2008 ◽  
Vol 36 (2) ◽  
pp. 141-147 ◽  
Author(s):  
Sabine Pokutta ◽  
Frauke Drees ◽  
Soichiro Yamada ◽  
W. James Nelson ◽  
William I. Weis
Keyword(s):  
Live Cell Imaging ◽  
Cell Imaging ◽  
Adherens Junction ◽  
Structural Data ◽  
Cell Contact ◽  
Related Protein ◽  
Imaging Studies ◽  
Actin Networks ◽  
Junction Formation ◽  
Cell Cell

Cadherins are transmembrane adhesion molecules that mediate homotypic cell–cell contact. In adherens junctions, the cytoplasmic domain of cadherins is functionally linked to the actin cytoskeleton through a series of proteins known as catenins. E-cadherin binds to β-catenin, which in turn binds to α-catenin to form a ternary complex. α-Catenin also binds to actin, and it was assumed previously that α-catenin links the cadherin–catenin complex to actin. However, biochemical, structural and live-cell imaging studies of the cadherin–catenin complex and its interaction with actin show that binding of β-catenin to α-catenin prevents the latter from binding to actin. Biochemical and structural data indicate that α-catenin acts as an allosteric protein whose conformation and activity changes depending on whether or not it is bound to β-catenin. Initial contacts between cells occur on dynamic lamellipodia formed by polymerization of branched actin networks, a process controlled by the Arp2/3 (actin-related protein 2/3) complex. α-Catenin can suppress the activity of Arp2/3 by competing for actin filaments. These findings lead to a model for adherens junction formation in which clustering of the cadherin–β-catenin complex recruits high levels of α-catenin that can suppress the Arp2/3 complex, leading to cessation of lamellipodial movement and formation of a stable contact. Thus α-catenin appears to play a central role in cell–cell contact formation.

scholarly journals The formation of ordered nanoclusters controls cadherin anchoring to actin and cell–cell contact fluidity

2015 ◽  
Vol 210 (2) ◽  
pp. 333-346 ◽  
Author(s):  
Pierre-Olivier Strale ◽  
Laurence Duchesne ◽  
Grégoire Peyret ◽  
Lorraine Montel ◽  
Thao Nguyen ◽  
...  
Keyword(s):  
Adherens Junction ◽  
Intercellular Junctions ◽  
Cell Contact ◽  
Collective Cell Migration ◽  
Contact Stability ◽  
Junction Formation ◽  
Mediate Cell ◽  
The Stability ◽  
E Cadherin ◽  
Cell Cell

Oligomerization of cadherins could provide the stability to ensure tissue cohesion. Cadherins mediate cell–cell adhesion by forming trans-interactions. They form cis-interactions whose role could be essential to stabilize intercellular junctions by shifting cadherin clusters from a fluid to an ordered phase. However, no evidence has been provided so far for cadherin oligomerization in cellulo and for its impact on cell–cell contact stability. Visualizing single cadherins within cell membrane at a nanometric resolution, we show that E-cadherins arrange in ordered clusters, providing the first demonstration of the existence of oligomeric cadherins at cell–cell contacts. Studying the consequences of the disruption of the cis-interface, we show that it is not essential for adherens junction formation. Its disruption, however, increased the mobility of junctional E-cadherin. This destabilization strongly affected E-cadherin anchoring to actin and cell–cell rearrangement during collective cell migration, indicating that the formation of oligomeric clusters controls the anchoring of cadherin to actin and cell–cell contact fluidity.

Protein Zero Is Necessary for E-Cadherin-Mediated Adherens Junction Formation in Schwann Cells

2001 ◽  
Vol 18 (6) ◽  
pp. 606-618 ◽  
Author(s):  
Daniela Maria Menichella ◽  
Edgardo J. Arroyo ◽  
Rajeshwar Awatramani ◽  
Theodore Xu ◽  
Pierluigi Baron ◽  
...  
Keyword(s):  
Schwann Cells ◽  
Adherens Junction ◽  
Junction Formation ◽  
Protein Zero ◽  
E Cadherin

Rac is a dominant regulator of cadherin-directed actin assembly that is activated by adhesive ligation independently of Tiam1

2007 ◽  
Vol 292 (3) ◽  
pp. C1061-C1069 ◽  
Author(s):  
Astrid Kraemer ◽  
Marita Goodwin ◽  
Suzie Verma ◽  
Alpha S. Yap ◽  
Radiya G. Ali
Keyword(s):  
Signaling Pathway ◽  
Dominant Negative ◽  
Signaling Cascades ◽  
Potential Contribution ◽  
Actin Assembly ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
Signaling Receptors ◽  
The Impact ◽  
E Cadherin

Classic cadherins function as adhesion-activated cell signaling receptors. On adhesive ligation, cadherins induce signaling cascades leading to actin cytoskeletal reorganization that is imperative for cadherin function. In particular, cadherin ligation activates actin assembly by the actin-related protein (Arp)2/3 complex, a process that critically affects the ability of cells to form and extend cadherin-based contacts. However, the signaling pathway(s) that activate Arp2/3 downstream of cadherin adhesion remain poorly understood. In this report we focused on the Rho family GTPases Rac and Cdc42, which can signal to Arp2/3. We found that homophilic engagement of E-cadherin simultaneously activates both Rac1 and Cdc42. However, by comparing the impact of dominant-negative Rac1 and Cdc42 mutants, we show that Rac1 is the dominant regulator of cadherin-directed actin assembly and homophilic contact formation. To pursue upstream elements of the Rac1 signaling pathway, we focused on the potential contribution of Tiam1 to cadherin-activated Rac signaling. We found that Tiam1 or the closely-related Tiam2/STEF1 was recruited to cell-cell contacts in an E-cadherin-dependent fashion. Moreover, a dominant-negative Tiam1 mutant perturbed cell spreading on cadherin-coated substrata. However, disruption of Tiam1 activity with dominant-negative mutants or RNA interference did not affect the ability of E-cadherin ligation to activate Rac1. We conclude that Rac1 critically influences cadherin-directed actin assembly as part of a signaling pathway independent of Tiam1.

scholarly journals Differential activation and function of Rho GTPases during Salmonella–host cell interactions

2006 ◽  
Vol 175 (3) ◽  
pp. 453-463 ◽  
Author(s):  
Jayesh C. Patel ◽  
Jorge E. Galán
Keyword(s):  
Rho Gtpases ◽  
Food Poisoning ◽  
Bacterial Pathogen ◽  
Cellular Responses ◽  
Host Cells ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
And Function

Salmonella enterica, the cause of food poisoning and typhoid fever, has evolved sophisticated mechanisms to modulate Rho family guanosine triphosphatases (GTPases) to mediate specific cellular responses such as actin remodeling, macropinocytosis, and nuclear responses. These responses are largely the result of the activity of a set of bacterial proteins (SopE, SopE2, and SopB) that, upon delivery into host cells via a type III secretion system, activate specific Rho family GTPases either directly (SopE and SopE2) or indirectly (SopB) through the stimulation of an endogenous exchange factor. We show that different Rho family GTPases play a distinct role in Salmonella-induced cellular responses. In addition, we report that SopB stimulates cellular responses by activating SH3-containing guanine nucleotide exchange factor (SGEF), an exchange factor for RhoG, which we found plays a central role in the actin cytoskeleton remodeling stimulated by Salmonella. These results reveal a remarkable level of complexity in the manipulation of Rho family GTPases by a bacterial pathogen.

scholarly journals Cdc42 GTPase regulates ESCRTs in nuclear envelope sealing and ER remodeling

2020 ◽  
Vol 219 (8) ◽  
Author(s):  
Michelle Seiko Lu ◽  
David G. Drubin
Keyword(s):  
Cell Migration ◽  
Genetic Analysis ◽  
Nuclear Envelope ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Molecular Switches ◽  
Small Gtpases ◽  
Cytoskeletal Remodeling ◽  
Cell Divisions ◽  
Rho Family

Small GTPases of the Rho family are binary molecular switches that regulate a variety of processes including cell migration and oriented cell divisions. Known Cdc42 effectors include proteins involved in cytoskeletal remodeling and kinase-dependent transcription induction, but none are involved in the maintenance of nuclear envelope integrity or ER morphology. Maintenance of nuclear envelope integrity requires the EndoSomal Complexes Required for Transport (ESCRT) proteins, but how they are regulated in this process remains unknown. Here, we show by live-cell imaging a novel Cdc42 localization with ESCRT proteins at sites of nuclear envelope and ER fission and, by genetic analysis of cdc42 mutant yeast, uncover a unique Cdc42 function in regulation of ESCRT proteins at the nuclear envelope and sites of ER tubule fission. Our findings implicate Cdc42 in nuclear envelope sealing and ER remodeling, where it regulates ESCRT disassembly to maintain nuclear envelope integrity and proper ER architecture.

scholarly journals Rear-polarized Wnt5a-receptor-actin-myosin-polarity (WRAMP) structures promote the speed and persistence of directional cell migration

2017 ◽  
Vol 28 (14) ◽  
pp. 1924-1936 ◽  
Author(s):  
Mary Katherine Connacher ◽  
Jian Wei Tay ◽  
Natalie G. Ahn
Keyword(s):  
Cell Migration ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Cell Movement ◽  
Leading Edge ◽  
Cellular Mechanism ◽  
Directional Movement ◽  
New Directions ◽  
And Function ◽  
Directional Cell Migration

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.

scholarly journals RNA-Selective, Live Cell Imaging Probes for Studying Nuclear Structure and Function

2006 ◽  
Vol 13 (6) ◽  
pp. 615-623 ◽  
Author(s):  
Qian Li ◽  
Yunkyung Kim ◽  
Joshua Namm ◽  
Amita Kulkarni ◽  
Gus R. Rosania ◽  
...  
Keyword(s):  
Nuclear Structure ◽  
Live Cell Imaging ◽  
Cell Imaging ◽  
Structure And Function ◽  
Live Cell ◽  
Imaging Probes ◽  
And Function

scholarly journals DLG-1 Is a MAGUK Similar to SAP97 and Is Required for Adherens Junction Formation

2001 ◽  
Vol 12 (11) ◽  
pp. 3465-3475 ◽  
Author(s):  
Bonnie L. Firestein ◽  
Christopher Rongo
Keyword(s):  
Cell Polarity ◽  
Adherens Junctions ◽  
Adherens Junction ◽  
Cell Junctions ◽  
Permeability Barrier ◽  
Cortical Actin ◽  
Interaction Domain ◽  
Amino Terminal ◽  
Junction Formation ◽  
And Function

Cellular junctions are critical for intercellular communication and for the assembly of cells into tissues. Cell junctions often consist of tight junctions, which form a permeability barrier and prevent the diffusion of lipids and proteins between cell compartments, and adherens junctions, which control the adhesion of cells and link cortical actin filaments to attachment sites on the plasma membrane. Proper tight junction formation and cell polarity require the function of membrane-associated guanylate kinases (MAGUKs) that contain the PDZ protein-protein interaction domain. In contrast, less is known about how adherens junctions are assembled. Here we describe how the PDZ-containing protein DLG-1 is required for the proper formation and function of adherens junctions in Caenorhabditis elegans. DLG-1 is a MAGUK protein that is most similar in sequence to mammalian SAP97, which is found at both synapses of the CNS, as well as at cell junctions of epithelia. DLG-1 is localized to adherens junctions, and DLG-1 localization is mediated by an amino-terminal domain shared with SAP97 but not found in other MAGUK family members. DLG-1 recruits other proteins and signaling molecules to adherens junctions, while embryos that lack DLG-1 fail to recruit the proteins AJM-1 and CPI-1 to adherens junctions. DLG-1 is required for the proper organization of the actin cytoskeleton and for the morphological elongation of embryos. In contrast to other proteins that have been observed to affect adherens junction assembly and function, DLG-1 is not required to maintain cell polarity. Our results suggest a new function for MAGUK proteins distinct from their role in cell polarity.

Sign in / Sign up

Export Citation Format

Share Document