Rescuing desmoplakin function in extra-embryonic ectoderm reveals the importance of this protein in embryonic heart, neuroepithelium, skin and vasculature

Development ◽  
2001 ◽  
Vol 128 (6) ◽  
pp. 929-941
Author(s):  
G.I. Gallicano ◽  
C. Bauer ◽  
E. Fuchs
Keyword(s):  
Heart Muscle ◽  
Intercellular Junctions ◽  
Beta Catenin ◽  
Epithelial Polarity ◽  
Wild Type ◽  
Desmosomal Cadherins ◽  
Embryonic Tissues ◽  
Tissue Integrity ◽  
Development Proceeds ◽  
Embryonic Ectoderm

Desmosomes mediate intercellular adhesion through desmosomal cadherins, which interface with plakoglobin (PG) and desmoplakin (DP) to associate with the intermediate filament (IF) cytoskeleton. Desmosomes first assemble in the E3.5 mouse trophectoderm, concomitant with establishment of epithelial polarity and appearance of a blastocoel cavity. Increasing in size and number, desmosomes continue their prominence in extra-embryonic tissues, but as development proceeds, they also become abundant in a number of embryonic tissues, including heart muscle, epidermis and neuroepithelium. Previously, we explored the functional importance of desmosomes by ablating the Dsp gene. Homozygous Dsp mutant embryos progressed through implantation, but did not survive beyond E6.5, owing to a loss or instability of desmosomes and tissue integrity. We have now rescued the extra-embryonic tissues by aggregation of tetraploid (wild-type) and diploid (Dsp mutant) morulae. These animals survive several days longer, but die shortly after gastrulation, with major defects in the heart muscle, neuroepithelium and skin epithelium, all of which possess desmosomes, as well as the microvasculature, which does not. Interestingly, although wild-type endothelial cells of capillaries do not form desmosomes, they possess unusual intercellular junctions composed of DP, PG and VE-cadherin. The severity in phenotype and the breadth of defects in the Dsp mutant embryo is greater than PG mutant embryos, substantiating redundancy between PG and other armadillo proteins (e.g. beta-catenin). The timing of lethality is similar to that of the VE-cadherin null embryo, suggesting that a participating cause of death may be a defect in vasculature, not reported for PG null embryos.

scholarly journals Desmoplakin Is Required Early in Development for Assembly of Desmosomes and Cytoskeletal Linkage

1998 ◽  
Vol 143 (7) ◽  
pp. 2009-2022 ◽  
Author(s):  
G. Ian Gallicano ◽  
Panos Kouklis ◽  
Christoph Bauer ◽  
Mei Yin ◽  
Valeri Vasioukhin ◽  
...  
Keyword(s):  
Critical Role ◽  
Early Embryo ◽  
Cell Junctions ◽  
Epithelial Polarity ◽  
Tissue Architecture ◽  
Desmosomal Cadherins ◽  
Tissue Integrity ◽  
Classical Cadherins ◽  
Mediate Cell ◽  
Cell Cell

Desmosomes first assemble in the E3.5 mouse trophectoderm, concomitant with establishment of epithelial polarity and appearance of a blastocoel cavity. Throughout development, they increase in size and number and are especially abundant in epidermis and heart muscle. Desmosomes mediate cell–cell adhesion through desmosomal cadherins, which differ from classical cadherins in their attachments to intermediate filaments (IFs), rather than actin filaments. Of the proteins implicated in making this IF connection, only desmoplakin (DP) is both exclusive to and ubiquitous among desmosomes. To explore its function and importance to tissue integrity, we ablated the desmoplakin gene. Homozygous −/− mutant embryos proceeded through implantation, but did not survive beyond E6.5. Mutant embryos proceeded through implantation, but did not survive beyond E6.5. Surprisingly, analysis of these embryos revealed a critical role for desmoplakin not only in anchoring IFs to desmosomes, but also in desmosome assembly and/or stabilization. This finding not only unveiled a new function for desmoplakin, but also provided the first opportunity to explore desmosome function during embryogenesis. While a blastocoel cavity formed and epithelial cell polarity was at least partially established in the DP (−/−) embryos, the paucity of desmosomal cell–cell junctions severely affected the modeling of tissue architecture and shaping of the early embryo.

scholarly journals Desmosomal cadherins utilize distinct kinesins for assembly into desmosomes

2011 ◽  
Vol 195 (7) ◽  
pp. 1185-1203 ◽  
Author(s):  
Oxana E. Nekrasova ◽  
Evangeline V. Amargo ◽  
William O. Smith ◽  
Jing Chen ◽  
Geri E. Kreitzer ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Epithelial Cells ◽  
Adhesion Molecules ◽  
Intercellular Junctions ◽  
Differential Regulation ◽  
Minimal Impact ◽  
Desmosomal Cadherins ◽  
Tissue Integrity ◽  
Functional Interference ◽  
Dependent Transport

The desmosomal cadherins, desmogleins (Dsgs) and desmocollins (Dscs), comprise the adhesive core of intercellular junctions known as desmosomes. Although these adhesion molecules are known to be critical for tissue integrity, mechanisms that coordinate their trafficking into intercellular junctions to regulate their proper ratio and distribution are unknown. We demonstrate that Dsg2 and Dsc2 both exhibit microtubule-dependent transport in epithelial cells but use distinct motors to traffic to the plasma membrane. Functional interference with kinesin-1 blocked Dsg2 transport, resulting in the assembly of Dsg2-deficient junctions with minimal impact on distribution of Dsc2 or desmosomal plaque components. In contrast, inhibiting kinesin-2 prevented Dsc2 movement and decreased its plasma membrane accumulation without affecting Dsg2 trafficking. Either kinesin-1 or -2 deficiency weakened intercellular adhesion, despite the maintenance of adherens junctions and other desmosome components at the plasma membrane. Differential regulation of desmosomal cadherin transport could provide a mechanism to tailor adhesion strength during tissue morphogenesis and remodeling.

scholarly journals The estrogen-dependent c-JunER protein causes a reversible loss of mammary epithelial cell polarity involving a destabilization of adherens junctions.

1996 ◽  
Vol 132 (6) ◽  
pp. 1115-1132 ◽  
Author(s):  
I Fialka ◽  
H Schwarz ◽  
E Reichmann ◽  
M Oft ◽  
M Busslinger ◽  
...  
Keyword(s):  
Growth Factor ◽  
Epithelial Cells ◽  
Target Genes ◽  
Egf Receptor ◽  
Mammary Epithelial ◽  
Breast Development ◽  
Beta Catenin ◽  
Epithelial Polarity ◽  
Tubular Structures ◽  
Tissue Organization

Members of the epidermal growth factor (EGF) receptor family are known to be specifically involved in mammary carcinogenesis. As a nuclear target of activated receptors, we examined c-Jun in mammary epithelial cells. For this, we used a c-JunER fusion protein which was tightly controlled by estrogen. Activation of the JunER by hormone resulted in the transcriptional regulation of a variety of AP-1 target genes. Hormone-activated JunER induced the loss of epithelial polarity, a disruption of intercellular junctions and normal barrier function and the formation of irregular multilayers. These changes were completely reversible upon hormone withdrawal. Loss of epithelial polarity involved redistribution of both apical and basolateral proteins to the entire plasma membrane. The redistribution of E-cadherin and beta-catenin was accompanied by a destabilization of complexes formed between these two proteins, leading to an enrichment of beta-catenin in the detergent-soluble fraction. Uninduced cells were able to form three-dimensional tubular structures in collagen I gels which were disrupted upon JunER activation, leading to irregular cell aggregates. The JunER-induced disruption of tubular structures was dependent on active signaling by growth factors. Moreover, the effects of JunER could be mimicked in normal cells by the addition of acidic fibroblast growth factor (aFGF). These data suggest that a possible function of c-Jun in epithelial cells is to modulate epithelial polarity and regulate tissue organization, processes which may be equally important for both normal breast development and as initiating steps in carcinogenesis.

Abstract 361: Creg1 Interacts With Sec8 to Promote Cell-cell Adhesion During Cardiomyogenesis

2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Jie Liu ◽  
Yanmei Qi ◽  
Shu-Chan Hsu ◽  
Siavash Saadat ◽  
Saum Rahimi ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Es Cells ◽  
Embryonic Stem ◽  
Intercellular Junctions ◽  
Amino Acid Residues ◽  
Loss Of Function ◽  
Wild Type ◽  
Adhesion Sites ◽  
Cell Cell

Cellular repressor of E1A-stimulated genes 1 (CREG1) is a 24 kD glycoprotein essential for early embryonic development. Our immunofluorescence studies revealed that CREG1 is highly expressed at myocyte junctions in both embryonic and adult hearts. To explore it role in cardiomyogenesis, we employed gain- and loss-of-function analyses demonstrating that CREG1 is required for the differentiation of mouse embryonic stem (ES) cell into cohesive myocardium-like structures. Chimeric cultures of wild-type and CREG1 knockout ES cells expressing cardiac-specific reporters showed that the cardiomyogenic effect of CREG1 is cell autonomous. Furthermore, we identified a novel interaction between CREG1 and Sec8 of the exocyst complex, which tethers vesicles to the plasma membrane. Mutations of the amino acid residues D141 and P142 to alanine in CREG1 abolished its binding to Sec8. To address the role of the CREG1-Sec8 interaction in cardiomyogenesis, we rescued CREG1 knockout ES cells with wild-type and Sec8-binding mutant CREG1 and showed that CREG1 binding to Sec8 promotes cardiomyocyte differentiation and cohesion. Mechanistically, CREG1, Sec8 and N-cadherin all localize at cell-cell adhesion sites. CREG1 overexpression enhances the assembly of adherens and gap junctions. By contrast, its knockout inhibits the Sec8-N-cadherin interaction and induces their degradation. Finally, shRNA-mediated knockdown of Sec8 leads to cardiomyogenic defects similar to CREG1 knockout. These results suggest that the CREG1 binding to Sec8 enhances the assembly of intercellular junctions and promotes cardiomyogenesis.

C. elegans POP-1/TCF functions in a canonical Wnt pathway that controls cell migration and in a noncanonical Wnt pathway that controls cell polarity

Development ◽  
2001 ◽  
Vol 128 (4) ◽  
pp. 581-590 ◽  
Author(s):  
M. Herman
Keyword(s):  
T Cells ◽  
T Cell ◽  
Cell Polarity ◽  
Wnt Pathway ◽  
Beta Catenin ◽  
Wild Type ◽  
C Elegans ◽  
Cell Divisions ◽  
Canonical Wnt Pathway ◽  
Canonical Wnt

In Caenorhabditis elegans, Wnt signaling pathways are important in controlling cell polarity and cell migrations. In the embryo, a novel Wnt pathway functions through a (beta)-catenin homolog, WRM-1, to downregulate the levels of POP-1/Tcf in the posterior daughter of the EMS blastomere. The level of POP-1 is also lower in the posterior daughters of many anteroposterior asymmetric cell divisions during development. I have found that this is the case for of a pair of postembryonic blast cells in the tail. In wild-type animals, the level of POP-1 is lower in the posterior daughters of the two T cells, TL and TR. Furthermore, in lin-44/Wnt mutants, in which the polarities of the T cell divisions are frequently reversed, the level of POP-1 is frequently lower in the anterior daughters of the T cells. I have used a novel RNA-mediated interference technique to interfere specifically with pop-1 zygotic function and have determined that pop-1 is required for wild-type T cell polarity. Surprisingly, none of the three C. elegans (beta)-catenin homologs appeared to function with POP-1 to control T cell polarity. Wnt signaling by EGL-20/Wnt controls the migration of the descendants of the QL neuroblast by regulating the expression the Hox gene mab-5. Interfering with pop-1 zygotic function caused defects in the migration of the QL descendants that mimicked the defects in egl-20/Wnt mutants and blocked the expression of mab-5. This suggests that POP-1 functions in the canonical Wnt pathway to control QL descendant migration and in novel Wnt pathways to control EMS and T cell polarities.

Targeting of the myosin-I myr 3 to intercellular adherens type junctions induced by dominant active Cdc42 in HeLa cells

1998 ◽  
Vol 111 (18) ◽  
pp. 2779-2788 ◽  
Author(s):  
H.E. Stoffler ◽  
U. Honnert ◽  
C.A. Bauer ◽  
D. Hofer ◽  
H. Schwarz ◽  
...  
Keyword(s):  
Hela Cells ◽  
Adherens Junction ◽  
Intercellular Junctions ◽  
Distinct Type ◽  
Beta Catenin ◽  
Tail Domain ◽  
Filamentous Actin ◽  
Myosin I ◽  
Myosin Motor Domain ◽  
Constitutively Active

Myr 3, a member of the myosin-I family from rat, is shown in this study to be localized at adherens-type intercellular junctions in epithelial and nonepithelial tissues. Formation of intercellular junctions and the accompanying recruitment of myr 3 to these junctions involves signaling by the Rho subfamily of small GTP-binding proteins. This conclusion is based on studies with HtTA-1 HeLa cells that were induced by overexpression of constitutively active Cdc42Hs to form typical adherens-type intercellular junctions enriched in cadherins (N-cadherin), beta-catenin, filamentous actin and myr 3. Recruitement of myr 3 to Cdc42-induced adherens junctions in HeLa cells was dependent on a short region of the tail domain and a functional myosin motor domain, but was independent of its myosin-I tail homology and SH3 regions. Overexpression of constitutively active Rac1 induced a distinct type of adherens junction in HeLa cells that was characterized by elaborate intercellular interdigitations enriched in N-cadherin, beta-catenin and F-actin. Myr 3 was often present, but not specifically enriched in the intercellular junctions induced by constitutively active Rac1.

Differential expression of cell-cell and cell-substratum adhesion proteins along the kidney nephron

1995 ◽  
Vol 269 (6) ◽  
pp. C1433-C1449 ◽  
Author(s):  
P. A. Piepenhagen ◽  
W. J. Nelson
Keyword(s):  
Cell Adhesion ◽  
Immunofluorescence Microscopy ◽  
The Other ◽  
Beta Catenin ◽  
Desmosomal Cadherins ◽  
Functional Differences ◽  
Associated Proteins ◽  
Capillary Endothelial Cells ◽  
Mediate Cell ◽  
Cell Cell

Structural and functional differences among epithelial cells of kidney nephrons may be regulated by variations in cell-to-cell (cell-cell) and cell-to-substratum (cell-substratum) junctions. Using immunofluorescence microscopy, we demonstrate that the cadherin-associated proteins alpha- and beta-catenin are localized to basolateral membranes of cells in all nephron segments, whereas plakoglobin, a protein associated with both classical and desmosomal cadherins, is localized to noninterdigitated lateral membranes in the distal half of the nephron where it colocalizes with desmoplakin and cytokeratin K8. Plakoglobin is also present in capillary endothelial cells where staining for the other catenins and desmosomal proteins is not observed. Immunofluorescence for laminin A and alpha 6-integrin, proteins that mediate cell-substratum contacts, reveal no correlations with the other staining patterns observed. These data indicate that plakoglobin and beta-catenin subserve distinct functions in cell-cell adhesion and suggest that E-cadherin-mediated contacts generate a basal level of cell-cell adhesion, whereas desmosomal junctions provide additional strength to cell-cell contacts in the distal nephron.

scholarly journals Downregulation of integrins by von Hippel-Lindau (VHL) tumor suppressor protein is independent of VHL-directed hypoxia-inducible factor alpha degradation

2008 ◽  
Vol 86 (3) ◽  
pp. 227-234 ◽  
Author(s):  
Qingzhou Ji ◽  
Robert D. Burk
Keyword(s):  
Tumor Suppressor ◽  
Clear Cell ◽  
Hypoxia Inducible Factor ◽  
Intercellular Junctions ◽  
Suppressor Gene ◽  
Wild Type ◽  
Von Hippel Lindau ◽  
Degradation Activity ◽  
Factor Alpha ◽  
Vhl Tumor Suppressor Protein

Inactivation of the von Hippel-Lindau (VHL) tumor suppressor gene occurs in the majority of clear-cell renal cell carcinomas (RCCs). It was previously shown that VHL decreased the abundance of integrins α2, α5, and β1, which is consistent with VHL-associated changes in cell–cell and cell – extracellular matrix adhesions. We investigated the mechanism by which VHL downregulates integrins. Although VHL can target hypoxia-inducible factor alpha (HIFα) subunits for degradation, VHL-dependent reduction of integrins was independent of O2 concentration and HIFα levels. VHL reduced the half-lives of integrins, and this activity was blocked by proteasomal inhibition. Although ectopically expressed FLAG-VHL retained HIFα degradation activity, it neither downregulated integrins nor promoted adherens and tight intercellular junctions, in contrast to expressed wild-type VHL. Moreover, integrins co-immunoprecipitated with wild-type VHL, but not FLAG-VHL. These data indicate that the downregulation of integrins by VHL is distinct from the regulation of HIFα subunits by VHL, and suggests that the loss of this activity contributes to VHL-associated RCC development through disruption of adherens and tight junctions.

Placental vascularisation requires the AP-1 component fra1

Development ◽  
2000 ◽  
Vol 127 (22) ◽  
pp. 4937-4948 ◽  
Author(s):  
M. Schreiber ◽  
Z.Q. Wang ◽  
W. Jochum ◽  
I. Fetka ◽  
C. Elliott ◽  
...  
Keyword(s):  
Marked Decrease ◽  
Vascular Endothelial Cells ◽  
Es Cells ◽  
Early Gene ◽  
Marker Genes ◽  
Vascular Endothelial ◽  
Wild Type ◽  
Mouse Development ◽  
Gene Encoding ◽  
Embryonic Tissues

Fra1 is an immediate-early gene encoding a member of the AP-1 transcription factor family, which has diverse roles in development and oncogenesis. To determine the function of Fra1 in mouse development, the gene was inactivated by gene targeting. Foetuses lacking Fra1 were severely growth retarded and died between E10.0 and E10.5, owing to defects in extra-embryonic tissues. The placental labyrinth layer, where X-gal staining revealed expression of Fra1, was reduced in size and largely avascular, owing to a marked decrease in the number of vascular endothelial cells, as shown by the lack of Flk1 expression. In contrast, the spongiotrophoblast layer was unaffected and expressed the marker genes 4311 (Tpbp) and Flt1. Furthermore, mutant foetuses exhibited yolk-sac defects that may contribute to their growth retardation and lethality. Importantly, when the placental defect was rescued by injection of Fra1(−)(/)(−) ES cells into tetraploid wild-type blastocysts, Fra1(−)(/)(−) pups were obtained that were no longer growth retarded and survived up to 2 days after birth without apparent phenotypic defects. These data indicate that a defect in the extra-embryonic compartment is causal to the observed lethality, and suggest that Fra1 plays a crucial role in establishing normal vascularisation of the placenta.

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