Abstract 19664: Molecular Mechanisms of Gα12 Regulated E-cadherin Shedding in Epithelial Cells

Circulation ◽  
2014 ◽  
Vol 130 (suppl_2) ◽  
Author(s):  
Jen Xu ◽  
Yong Wu ◽  
Suyang Li ◽  
Kenneth Lim ◽  
Tianqing Kong ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Molecular Mechanisms ◽  
Mdck Cells ◽  
Active Form ◽  
Cell Junctions ◽  
Mice Model ◽  
Polycystic Kidneys ◽  
Cystic Fluid ◽  
Kidney Cysts ◽  
E Cadherin

Introduction and hypothesis: E-cadherin plays an important role in maintaining the integrity of cell polarity and cell junctions. It is one of the major proteins that forms part of the polycystin-1 (PC1) complex in renal epithelial cells. We previously showed that deletion of the PC1-regulated protein, Gα12, protected kidneys from development of kidney cysts induced by Pkd1 inactivation and activation of Gα12 increased the shedding of E-cadherin in autosomal dominant polycystic kidney disease (ADPKD). The objective of this study was to determine the molecular mechanisms by which Gα12 regulates E-cadherin shedding. Methods: We analyzed polycystic kidneys from human and from Pkd1 knock-out mice. Using Madin-Darby canine kidney (MDCK) cells, we developed a Pkd1 deletion in vitro model using Pkd1 siRNA. Results: Our data shows that Pkd1 deletion caused accumulation of cleaved E-cadherin fragment in renal cystic fluid in both human polycystic kidneys and in our mice model. In addition, we found that activation of Gα12 increased the active form of ADAM10, the cleavage protein for E-cadherin in both human and mice polycystic kidneys, in vivo. In our MDCK cellular three-dimensional culture system, Gα12 activation promoted cyst formation and this phenomenon was inhibited by ADAM10 knockdown. Furthermore, knockdown of ADAM10 abolished the shedding of E-cadherin caused by Gα12 activation. These data indicate that ADAM10 is the major sheddase for cleavage of E-cadherin caused by Gα12 activation. Conclusion: Our results demonstrate that Gα12 activation increases ADAM10 activity and promotes the ectodomain shedding of E-cadherin, which is an important mechanism in the development of kidney cysts induced by Pkd1 deletion in ADPKD.

scholarly journals Differential regulation of junctional complex assembly in renal epithelial cell lines

2003 ◽  
Vol 285 (1) ◽  
pp. C102-C111 ◽  
Author(s):  
Shobha Gopalakrishnan ◽  
Mark A. Hallett ◽  
Simon J. Atkinson ◽  
James. A. Marrs
Keyword(s):  
Epithelial Cells ◽  
Tight Junction ◽  
Rho Gtpase ◽  
Mdck Cells ◽  
Adherens Junction ◽  
Stress Fiber ◽  
Cell Junctions ◽  
Junctional Complex ◽  
Complex Assembly ◽  
E Cadherin

Several signaling pathways that regulate tight junction and adherens junction assembly are being characterized. Calpeptin activates stress fiber assembly in fibroblasts by inhibiting SH2-containing phosphatase-2 (SHP-2), thereby activating Rho-GTPase signaling. Here, we have examined the effects of calpeptin on stress fiber and junctional complex assembly in Madin-Darby canine kidney (MDCK) and LLC-PK epithelial cells. Calpeptin induced disassembly of stress fibers and inhibition of Rho GTPase activity in MDCK cells. Interestingly, calpeptin augmented stress fiber formation in LLC-PK epithelial cells. Calpeptin treatment of MDCK cells resulted in a displacement of zonula occludens-1 (ZO-1) and occludin from cell-cell junctions and a loss of phosphotyrosine on ZO-1 and ZO-2, without any detectable effect on tight junction permeability. Surprisingly, calpeptin increased paracellular permeability in LLC-PK cells even though it did not affect tight junction assembly. Calpeptin also modulated adherens junction assembly in MDCK cells but not in LLC-PK cells. Calpeptin treatment of MDCK cells induced redistribution of E-cadherin and β-catenin from intercellular junctions and reduced the association of p120ctn with the E-cadherin/catenin complex. Together, our studies demonstrate that calpeptin differentially regulates stress fiber and junctional complex assembly in MDCK and LLC-PK epithelial cells, indicating that these pathways may be regulated in a cell line-specific manner.

scholarly journals Depletion of E-Cadherin Disrupts Establishment but Not Maintenance of Cell Junctions in Madin-Darby Canine Kidney Epithelial Cells

2007 ◽  
Vol 18 (1) ◽  
pp. 189-200 ◽  
Author(s):  
Christopher T. Capaldo ◽  
Ian G. Macara
Keyword(s):  
Epithelial Cells ◽  
Mdck Cells ◽  
Morphological Changes ◽  
Cell Junctions ◽  
Cell Cortex ◽  
Apical Surface ◽  
Madin Darby Canine Kidney ◽  
Darby Canine Kidney ◽  
Canine Kidney ◽  
E Cadherin

E-cadherin forms calcium-dependent homophilic intercellular adhesions between epithelial cells. These contacts regulate multiple aspects of cell behavior, including the organization of intercellular tight junctions (TJs). To distinguish between the roles of E-cadherin in formation versus maintenance of junctions, Madin-Darby canine kidney (MDCK) cells were depleted of E-cadherin by RNA interference. Surprisingly, reducing E-cadherin expression had little effect on the protein levels or localization of adherens junction (AJ) or TJ markers. The cells underwent morphological changes, as the normally flat apical surface swelled into a dome. However, apical–basal polarity was not compromised, transmembrane resistance was normal, and zonula occludin protein 1 dynamics at the TJs were unchanged. Additionally, an E-cadherin/Cadherin-6 double knockdown also failed to disrupt established TJs, although β-catenin was lost from the cell cortex. Nevertheless, cells depleted of E-cadherin failed to properly reestablish cell polarity after junction disassembly. Recovery of cell–cell adhesion, transepithelial resistance, and the localization of TJ and AJ markers were all delayed. In contrast, depletion of α-catenin caused long-term disruption of junctions. These results indicate that E-cadherin and Cadherin-6 function as a scaffold for the construction of polarized structures, and they become largely dispensable in mature junctions, whereas α-catenin is essential for the maintenance of functional junctions.

scholarly journals Polycystin-1 and Gα12 regulate the cleavage of E-cadherin in kidney epithelial cells

2015 ◽  
Vol 47 (2) ◽  
pp. 24-32 ◽  
Author(s):  
Jen X. Xu ◽  
Tzong-Shi Lu ◽  
Suyan Li ◽  
Yong Wu ◽  
Lai Ding ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Signaling Pathway ◽  
Cell Polarity ◽  
Mdck Cells ◽  
Adherens Junction ◽  
Renal Epithelial Cells ◽  
Extracellular Milieu ◽  
Kidney Epithelial Cells ◽  
Autosomal Dominant Polycystic Kidney ◽  
E Cadherin

Interaction of polycystin-1 (PC1) and Gα12 is important for development of kidney cysts in autosomal dominant polycystic kidney disease (ADPKD). The integrity of cell polarity and cell-cell adhesions (mainly E-cadherin-mediated adherens junction) is altered in the renal epithelial cells of ADPKD. However, the key signaling pathway for this alteration is not fully understood. Madin-Darby canine kidney (MDCK) cells maintain the normal integrity of epithelial cell polarity and adherens junctions. Here, we found that deletion of Pkd1 increased activation of Gα12, which then promoted the cystogenesis of MDCK cells. The morphology of these cells was altered after the activation of Gα12. By using liquid chromatography-mass spectrometry, we found several proteins that could be related this change in the extracellular milieu. E-cadherin was one of the most abundant peptides after active Gα12 was induced. Gα12 activation or Pkd1 deletion increased the shedding of E-cadherin, which was mediated via increased ADAM10 activity. The increased shedding of E-cadherin was blocked by knockdown of ADAM10 or specific ADAM10 inhibitor GI254023X. Pkd1 deletion or Gα12 activation also changed the distribution of E-cadherin in kidney epithelial cells and caused β-catenin to shift from cell membrane to nucleus. Finally, ADAM10 inhibitor, GI254023 X, blocked the cystogenesis induced by PC1 knockdown or Gα12 activation in renal epithelial cells. Our results demonstrate that the E-cadherin/β-catenin signaling pathway is regulated by PC1 and Gα12 via ADAM10. Specific inhibition of this pathway, especially ADAM10 activity, could be a novel therapeutic regimen for ADPKD.

scholarly journals Deciliation Is Associated with Dramatic Remodeling of Epithelial Cell Junctions and Surface Domains

2009 ◽  
Vol 20 (1) ◽  
pp. 102-113 ◽  
Author(s):  
Christian E. Overgaard ◽  
Kaitlin M. Sanzone ◽  
Krystle S. Spiczka ◽  
David R. Sheff ◽  
Alexander Sandra ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Primary Cilia ◽  
Mdck Cells ◽  
Cell Junctions ◽  
Apical Trafficking ◽  
Epithelial Remodeling ◽  
Surface Domains ◽  
And Function ◽  
Mediated Reduction ◽  
Junction Proteins

Stress-induced shedding of motile cilia (autotomy) has been documented in diverse organisms and likely represents a conserved cellular reaction. However, little is known about whether primary cilia are shed from mammalian epithelial cells and what impact deciliation has on polarized cellular organization. We show that several chemically distinct agents trigger autotomy in epithelial cells. Surprisingly, deciliation is associated with a significant, but reversible increase in transepithelial resistance. This reflects substantial reductions in tight junction proteins associated with “leaky” nephron segments (e.g., claudin-2). At the same time, apical trafficking of gp80/clusterin and gp114/CEACAM becomes randomized, basal-lateral delivery of Na,K-ATPase is reduced, and expression of the nonciliary apical protein gp135/podocalyxin is greatly decreased. However, ciliogenesis-impaired MDCK cells do not undergo continual junction remodeling, and mature cilia are not required for autotomy-associated remodeling events. Deciliation and epithelial remodeling may be mechanistically linked processes, because RNAi-mediated reduction of Exocyst subunit Sec6 inhibits ciliary shedding and specifically blocks deciliation-associated down-regulation of claudin-2 and gp135. We propose that ciliary autotomy represents a signaling pathway that impacts the organization and function of polarized epithelial cells.

scholarly journals Oncogenic K-Ras Regulates Proliferation and Cell Junctions in Lung Epithelial Cells through Induction of Cyclooxygenase-2 and Activation of Metalloproteinase-9

2009 ◽  
Vol 20 (3) ◽  
pp. 791-800 ◽  
Author(s):  
Xue-Qing Wang ◽  
Howard Li ◽  
Vicki Van Putten ◽  
Robert A. Winn ◽  
Lynn E. Heasley ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Biological Effects ◽  
Three Dimensional ◽  
Lung Epithelial Cells ◽  
Cell Junctions ◽  
Prostaglandin E ◽  
Erk Activation ◽  
Lung Epithelial ◽  
Cox 2 ◽  
E Cadherin

Expression of oncogenic K-Ras is frequently observed in non–small-cell lung cancer. However, oncogenic K-Ras is not sufficient to transform lung epithelial cells and requires collaborating signals that have not been defined. To examine the biological effects of K-Ras in nontransformed lung epithelial cells, stable transfectants were generated in RL-65 cells, a spontaneously immortalized lung epithelial cell line. Expression of K-Ras resulted in extracellular signal-regulated kinase (ERK) activation, which mediated induction of cyclooxygenase (COX)-2 and increased prostaglandin E2 production. Epithelial cells expressing oncogenic K-Ras showed increased proliferation in two- and three-dimensional tissue culture and delayed formation of hollow acinar structures in three-dimensional matrigel cultures. These affects were mediated through COX-2–dependent activation of β-catenin signaling and inhibition of apoptosis. ERK activation also led to induction of metalloproteinase (MMP)-9 and cleavage of E-cadherin at two specific sites. This resulted in partial disruption of adherens junctions as determined by decreased transepithelial resistance (TER), and disruption of E-cadherin/β-catenin interactions. An MMP-9 inhibitor reversed the decrease in TER and inhibited β-catenin signaling. These data indicate that although expression of oncogenic K-Ras does not transform lung epithelial cells, it alters the phenotype of the cells by increasing proliferation and decreasing cell–cell contacts characteristic of epithelial cells.

scholarly journals Actin protrusions push on E-cadherin to maintain epithelial cell-cell adhesion

2019 ◽  
Author(s):  
John Xiao He Li ◽  
Vivian W. Tang ◽  
William M. Brieher
Keyword(s):  
Cell Adhesion ◽  
Actin Polymerization ◽  
Mdck Cells ◽  
Myosin Ii ◽  
Cell Junctions ◽  
Apical Junctions ◽  
Actin Protrusions ◽  
Adhesive Contacts ◽  
E Cadherin ◽  
Cell Cell

AbstractCadherin mediated cell-cell adhesion is actin dependent, but the precise role of actin in maintaining cell-cell adhesion is not fully understood. Actin polymerization-dependent protrusive activity is required to push distally separated cells close enough together to initiate contact. Whether protrusive activity is required to maintain adhesion in confluent sheets of epithelial cells is not known. By electron microscopy as well as live cell imaging, we have identified a population of protruding actin microspikes that operate continuously near apical junctions of polarized MDCK cells. Live imaging shows that microspikes containing E-cadherin extend into gaps between E-cadherin clusters on neighboring cells while reformation of cadherin clusters across the cell-cell boundary triggers microspike withdrawal. We identify Arp2/3, EVL, and CRMP-1 as three actin assembly factors necessary for microspike formation. Depleting these factors from cells using RNAi results in myosin II-dependent unzipping of cadherin adhesive bonds. Therefore, actin polymerization-dependent protrusive activity operates continuously at cadherin cell-cell junctions to keep them shut and to prevent myosin II-dependent contractility from tearing cadherin adhesive contacts apart.

Selective degradation of E-cadherin and dissolution of E-cadherin-catenin complexes in epithelial ischemia

2000 ◽  
Vol 278 (5) ◽  
pp. F847-F852 ◽  
Author(s):  
Kevin T. Bush ◽  
Tatsuo Tsukamoto ◽  
Sanjay K. Nigam
Keyword(s):  
Epithelial Cells ◽  
Mdck Cells ◽  
Transmembrane Protein ◽  
Adherens Junction ◽  
Intercellular Junctions ◽  
Atp Depletion ◽  
Cell Phenotype ◽  
Western Blots ◽  
Selective Degradation ◽  
E Cadherin

Ischemic epithelial cells are characterized by disruption of intercellular junctions and loss of apical-basolateral protein polarity, which are normally dependent on the integrity of the adherens junction (AJ). Biochemical analysis of both whole ischemic kidneys and ATP-depleted Madin-Darby canine kidney (MDCK) cells demonstrated a striking loss of E-cadherin (the transmembrane protein of the AJ) with the appearance and accumulation of an ∼80-kDa fragment reactive with anti-E-cadherin antibodies on Western blots of ATP-depleted MDCK cells. This apparent ischemia-induced degradation of E-cadherin was not blocked by either inhibitors of the major proteolytic pathways (i.e., proteasome, lysosome, or calpain), or by chelation of intracellular calcium, suggesting the involvement of a protease capable of functioning at low ATP and low calcium levels. Immunocytochemistry revealed the movement of several proteins normally comprising the AJ, including E-cadherin and β-catenin, away from lateral portions of the plasma membrane to intracellular sites. Moreover, rate-zonal centrifugation and immunoprecipitation with anti-E-cadherin and anti-β-catenin antibodies indicated that ATP depletion disrupted normal E-cadherin-catenin interactions, resulting in the dissociation of α- and γ-catenin from E-cadherin and β-catenin-containing complexes. Because the generation and maintenance of polarized epithelial cells are dependent upon E-cadherin-mediated cell-cell adhesion and normal AJ function, we propose that the rapid degradation of E-cadherin and dissolution of the AJ is a key step in the development of the ischemic epithelial cell phenotype. Furthermore, we hypothesize that the reassembly of the AJ after ischemia/ATP depletion may require a novel bioassembly mechanism involving recombination of newly synthesized and sorted E-cadherin with preexisting pools of catenins that have (temporally) redistributed intracellularly.

scholarly journals The unique trimeric assembly of the virulence factor HtrA from Helicobacter pylori occurs via N-terminal domain swapping

2019 ◽  
Vol 294 (20) ◽  
pp. 7990-8000 ◽  
Author(s):  
Zhemin Zhang ◽  
Qi Huang ◽  
Xuan Tao ◽  
Guobing Song ◽  
Peng Zheng ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Epithelial Cell ◽  
Virulence Factors ◽  
Molecular Mechanisms ◽  
Domain Swapping ◽  
Cell Junctions ◽  
Antibacterial Drug ◽  
Terminal Domain ◽  
H Pylori ◽  
E Cadherin

Knowledge of the molecular mechanisms of specific bacterial virulence factors can significantly contribute to antibacterial drug discovery. Helicobacter pylori is a Gram-negative microaerophilic bacterium that infects almost half of the world's population, leading to gastric disorders and even gastric cancer. H. pylori expresses a series of virulence factors in the host, among which high-temperature requirement A (HpHtrA) is a newly identified serine protease secreted by H. pylori. HpHtrA cleaves the extracellular domain of the epithelial cell surface adhesion protein E-cadherin and disrupts gastric epithelial cell junctions, allowing H. pylori to access the intercellular space. Here we report the first crystal structure of HpHtrA at 3.0 Å resolution. The structure revealed a new type of HtrA protease trimer stabilized by unique N-terminal domain swapping distinct from other known HtrA homologs. We further observed that truncation of the N terminus completely abrogates HpHtrA trimer formation as well as protease activity. In the presence of unfolded substrate, HpHtrA assembled into cage-like 12-mers or 24-mers. Combining crystallographic, biochemical, and mutagenic data, we propose a mechanistic model of how HpHtrA recognizes and cleaves the well-folded E-cadherin substrate. Our study provides a fundamental basis for the development of anti-H. pylori agents by using a previously uncharacterized HtrA protease as a target.

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