scholarly journals Ouabain Enhances Cell-Cell Adhesion Mediated by β1 Subunits of the Na+,K+-ATPase in CHO Fibroblasts

2019 ◽  
Vol 20 (9) ◽  
pp. 2111 ◽  
Author(s):  
Claudia Andrea Vilchis-Nestor ◽  
María Luisa Roldán ◽  
Angelina Leonardi ◽  
Juan G. Navea ◽  
Teresita Padilla-Benavides ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Epithelial Cells ◽  
Signaling Pathways ◽  
Chinese Hamster ◽  
Intercellular Junctions ◽  
Toxic Substances ◽  
Adhesive Properties ◽  
Α Subunit ◽  
Subsequent Effect ◽  
Crucial Characteristic

Adhesion is a crucial characteristic of epithelial cells to form barriers to pathogens and toxic substances from the environment. Epithelial cells attach to each other using intercellular junctions on the lateral membrane, including tight and adherent junctions, as well as the Na+,K+-ATPase. Our group has shown that non-adherent chinese hamster ovary (CHO) cells transfected with the canine β1 subunit become adhesive, and those homotypic interactions amongst β1 subunits of the Na+,K+-ATPase occur between neighboring epithelial cells. Ouabain, a cardiotonic steroid, binds to the α subunit of the Na+,K+-ATPase, inhibits the pump activity and induces the detachment of epithelial cells when used at concentrations above 300 nM. At nanomolar non-inhibiting concentrations, ouabain affects the adhesive properties of epithelial cells by inducing the expression of cell adhesion molecules through the activation of signaling pathways associated with the α subunit. In this study, we investigated whether the adhesion between β1 subunits was also affected by ouabain. We used CHO fibroblasts stably expressing the β1 subunit of the Na+,K+-ATPase (CHO β1), and studied the effect of ouabain on cell adhesion. Aggregation assays showed that ouabain increased the adhesion between CHO β1 cells. Immunofluorescence and biotinylation assays showed that ouabain (50 nM) increases the expression of the β1 subunit of the Na+,K+-ATPase at the cell membrane. We also examined the effect of ouabain on the activation of signaling pathways in CHO β1 cells, and their subsequent effect on cell adhesion. We found that cSrc is activated by ouabain and, therefore, that it likely regulates the adhesive properties of CHO β1 cells. Collectively, our findings suggest that the β1 subunit adhesion is modulated by the expression levels of the Na+,K+-ATPase at the plasma membrane, which is regulated by ouabain.

scholarly journals Ouabain enhances cell-cell adhesion mediated by β1-subunits of the Na+,K+-ATPase in CHO fibroblasts

2019 ◽  
Author(s):  
Claudia Andrea Vilchis-Nestor ◽  
María Luisa Roldán ◽  
Teresita Padilla-Benavides ◽  
Liora Shoshani
Keyword(s):  
Plasma Membrane ◽  
Cell Adhesion ◽  
Epithelial Cells ◽  
Signaling Pathways ◽  
Cell Adhesion Molecules ◽  
Basolateral Membrane ◽  
Adhesive Properties ◽  
Α Subunit ◽  
Cardiotonic Steroid ◽  
Pump Activity

AbstractAdhesion is an important characteristic of epithelial cells to provide a crucial barrier to pathogens and substances. In polarized epithelial cells, cell-adhesion depends on tight junctions, adherent junctions and the Na+,K+-ATPase. All these are located in the basolateral membrane of the cells. The hormone ouabain, a cardiotonic steroid, binds to the α subunit of the Na+,K+-ATPase, and inhibits the pump activity when used at above μM concentrations. At physiological nM concentrations, ouabain affects the adhesive properties of epithelial cells by inducing the expression of cell adhesion molecules through activation of signaling pathways associated to the α subunit. Our group showed that non-adherent CHO cells transfected with the canine β1subunit become adhesive, and that homotypic interactions between β1subunits of the Na+,K+-ATPase occur between neighboring epithelial cells. Therefore, in this study we investigated whether the adhesion between β1subunits was also affected by ouabain. We used CHO fibroblasts stably expressing the β1subunit of the Na+,K+-ATPase (CHO-β1) and studied the effect of ouabain on cell adhesion. Aggregation assays showed that ouabain increased the adhesion between CHO-β1cells. Immunofluorescence and biotinylation assays showed that ouabain (50 nM) increases the expression of the β1 subunit of the Na+,K+-ATPase at the cell membrane. We also screened the effect of ouabain on activation of signaling pathways in CHO-β1cells, and their effect on cell adhesion. We found that c-Src, is activated by ouabain and is therefore likely to regulate the adhesive properties of CHO-β1cells. Collectively, our findings suggest that the β1subunits adhesion is modulated by the levels of expression and activation of the Na+,K+-ATPase at the plasma membrane, which is regulated by ouabain.

scholarly journals RAGE ligands stimulate angiotensin II type I receptor (AT1) via RAGE/AT1 complex on the cell membrane

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Serina Yokoyama ◽  
Tatsuo Kawai ◽  
Koichi Yamamoto ◽  
Huang Yibin ◽  
Hiroko Yamamoto ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Cardiovascular Diseases ◽  
Epithelial Cells ◽  
G Protein ◽  
Rat Kidney ◽  
Chinese Hamster ◽  
Cellular Responses ◽  
Type I ◽  
Α Subunit ◽  
Mesenchymal Transition

AbstractThe receptor for advanced glycation end-products (RAGE) and the G protein-coupled angiotensin II (AngII) type I receptor (AT1) play a central role in cardiovascular diseases. It was recently reported that RAGE modifies AngII-mediated AT1 activation via the membrane oligomeric complex of the two receptors. In this study, we investigated the presence of the different directional crosstalk in this phenomenon, that is, the RAGE/AT1 complex plays a role in the signal transduction pathway of RAGE ligands. We generated Chinese hamster ovary (CHO) cells stably expressing RAGE and AT1, mutated AT1, or AT2 receptor. The activation of two types of G protein α-subunit, Gq and Gi, was estimated through the accumulation of inositol monophosphate and the inhibition of forskolin-induced cAMP production, respectively. Rat kidney epithelial cells were used to assess RAGE ligand-induced cellular responses. We determined that RAGE ligands activated Gi, but not Gq, only in cells expressing RAGE and wildtype AT1. The activation was inhibited by an AT1 blocker (ARB) as well as a RAGE inhibitor. ARBs inhibited RAGE ligand-induced ERK phosphorylation, NF-κB activation, and epithelial–mesenchymal transition of rat renal epithelial cells. Our findings suggest that the activation of AT1 plays a central role in RAGE-mediated cellular responses and elucidate the role of a novel molecular mechanism in the development of cardiovascular diseases.

scholarly journals The Small GTPase Rap1b: A Bidirectional Regulator of Platelet Adhesion Receptors

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Gianni Francesco Guidetti ◽  
Mauro Torti
Keyword(s):  
Cell Adhesion ◽  
Signaling Pathways ◽  
Platelet Adhesion ◽  
Thrombus Formation ◽  
Small Gtpases ◽  
Small Gtpase ◽  
Complex Pattern ◽  
Adhesive Properties ◽  
Adhesion Receptors ◽  
Inside Out

Integrins and other families of cell adhesion receptors are responsible for platelet adhesion and aggregation, which are essential steps for physiological haemostasis, as well as for the development of thrombosis. The modulation of platelet adhesive properties is the result of a complex pattern of inside-out and outside-in signaling pathways, in which the members of the Rap family of small GTPases are bidirectionally involved. This paper focuses on the regulation of the main Rap GTPase expressed in circulating platelets, Rap1b, downstream of adhesion receptors, and summarizes the most recent achievements in the investigation of the function of this protein as regulator of platelet adhesion and thrombus formation.

Analysis of the cell adhesion mechanism using somatic cell hybrids. I. Aggregation of hybrid cells between adhesive V79 and non-adhesive Ehrlich's ascites tumour cells

1980 ◽  
Vol 43 (1) ◽  
pp. 391-406
Author(s):  
H. Aoyama ◽  
T.S. Okada ◽  
M. Takeichi
Keyword(s):  
Cell Adhesion ◽  
Chinese Hamster ◽  
Hybrid Cells ◽  
Adhesive Properties ◽  
V79 Cells ◽  
Ascites Tumour ◽  
Independent Mechanism ◽  
Eat Cells ◽  
Hybrid Clones ◽  
Dependent Mechanism

V79 Chinese hamster cells dissociated with 1 nm EDTA retain 2 kinds of cell adhesion mechanisms, one dependent on Ca2+ and the other independent of Ca2+. Ehrlich's ascites tumour (EAT) cells are provided with neither Ca2+-dependent nor CA2+-independent mechanisms. Studies on the aggregation of cells of 25 different hybrid clones obtained by fusing these 2 lined cells revealed the following points with regard to adhesive properties of hybrid cells. (1) The activity of the Ca2+-independent mechanism was lower in most hybrid clones than in parental V79 cells. (2) There were a few hybrid clones whose Ca2+-dependent mechanism activity was lower than in V79 cells. In these clones, the Ca2+-independent mechanism was also less active than the parental cells. (3) A hybrid clone with reduced Ca2+-dependent mechanism activity only was not found. (4) All the hybrid clones have at least one set of chromosomes derived from V79. (5) The number of chromosomes derived from EAT cells tended to be less in hybrid clones with lower aggregative ability. These results can be explained by assuming that the activity of the Ca2+-independent and Ca2+-dependent mechanisms of V79 cells may be differently inhibited by genes contained in EAT cells.

scholarly journals R-Ras Signals through Specific Integrin α Cytoplasmic Domains to Promote Migration and Invasion of Breast Epithelial Cells

1999 ◽  
Vol 145 (5) ◽  
pp. 1077-1088 ◽  
Author(s):  
Patricia J. Keely ◽  
Elena V. Rusyn ◽  
Adrienne D. Cox ◽  
Leslie V. Parise
Keyword(s):  
Epithelial Cells ◽  
Signaling Pathways ◽  
Cytoplasmic Domain ◽  
Cellular Adhesion ◽  
Limiting Factors ◽  
Migration And Invasion ◽  
Cytoplasmic Domains ◽  
Α Subunit ◽  
Breast Epithelial Cells ◽  
Breast Epithelial

Specificity and modulation of integrin function have important consequences for cellular responses to the extracellular matrix, including differentiation and transformation. The Ras-related GTPase, R-Ras, modulates integrin affinity, but little is known of the signaling pathways and biological functions downstream of R-Ras. Here we show that stable expression of activated R-Ras or the closely related TC21 (R-Ras 2) induced integrin-mediated migration and invasion of breast epithelial cells through collagen and disrupted differentiation into tubule structures, whereas dominant negative R-Ras had opposite effects. These results imply novel roles for R-Ras and TC21 in promoting a transformed phenotype and in the basal migration and polarization of these cells. Importantly, R-Ras induced an increase in cellular adhesion and migration on collagen but not fibronectin, suggesting that R-Ras signals to specific integrins. This was further supported by experiments in which R-Ras enhanced the migration of cells expressing integrin chimeras containing the α2, but not the α5, cytoplasmic domain. In addition, a transdominant inhibition previously noted only between integrin β cytoplasmic domains was observed for the α2 cytoplasmic domain; α2β1-mediated migration was inhibited by the expression of excess α2 but not α5 cytoplasmic domain-containing chimeras, suggesting the existence of limiting factors that bind the integrin α subunit. Using pharmacological inhibitors, we found that R-Ras induced migration on collagen through a combination of phosphatidylinositol 3-kinase and protein kinase C, but not MAPK, which is distinct from the other Ras family members, Rac, Cdc42, and N- and K-Ras. Thus, R-Ras communicates with specific integrin α cytoplasmic domains through a unique combination of signaling pathways to promote cell migration and invasion.

scholarly journals The Small GTPases Rho and Rac Are Required for the Establishment of Cadherin-dependent Cell–Cell Contacts

1997 ◽  
Vol 137 (6) ◽  
pp. 1421-1431 ◽  
Author(s):  
Vania M.M. Braga ◽  
Laura M. Machesky ◽  
Alan Hall ◽  
Neil A. Hotchin
Keyword(s):  
Cell Adhesion ◽  
Epithelial Cells ◽  
Active Form ◽  
Intercellular Junctions ◽  
Small Gtpases ◽  
Cell Contacts ◽  
Calcium Dependent ◽  
Dependent Cell ◽  
Rho Family ◽  
Cell Cell

Cadherins are calcium-dependent cell–cell adhesion molecules that require the interaction of the cytoplasmic tail with the actin cytoskeleton for adhesive activity. Because of the functional relationship between cadherin receptors and actin filament organization, we investigated whether members of the Rho family of small GTPases are necessary for cadherin adhesion. In fibroblasts, the Rho family members Rho and Rac regulate actin polymerization to produce stress fibers and lamellipodia, respectively. In epithelial cells, we demonstrate that Rho and Rac are required for the establishment of cadherin-mediated cell–cell adhesion and the actin reorganization necessary to stabilize the receptors at sites of intercellular junctions. Blocking endogenous Rho or Rac selectively removed cadherin complexes from junctions induced for up to 3 h, while desmosomes were not perturbed. In addition, withdrawal of cadherins from intercellular junctions temporally precedes the removal of CD44 and integrins, other microfilament-associated receptors. Our data showed that the concerted action of Rho and Rac modulate the establishment of cadherin adhesion: a constitutively active form of Rac was not sufficient to stabilize cadherindependent cell–cell contacts when endogenous Rho was inhibited. Upon induction of calcium-dependent intercellular adhesion, there was a rapid accumulation of actin at sites of cell–cell contacts, which was prevented by blocking cadherin function, Rho or Rac activity. However, if cadherin complexes are clustered by specific antibodies attached to beads, actin recruitment to the receptors was perturbed by inhibiting Rac but not Rho. Our results provide new insights into the role of the small GTPases in the cadherin-dependent cell– cell contact formation and the remodelling of actin filaments in epithelial cells.

scholarly journals AG and UAG induce β-casein expression via activation of ERK1/2 and AKT pathways

2016 ◽  
Vol 56 (3) ◽  
pp. 213-225 ◽  
Author(s):  
Sunan Li ◽  
Juxiong Liu ◽  
Qingkang Lv ◽  
Chuan Zhang ◽  
Shiyao Xu ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Signaling Pathways ◽  
Mammary Epithelial Cells ◽  
Akt Signaling ◽  
Mammary Epithelial ◽  
Control Group ◽  
Dependent Manner ◽  
Α Subunit ◽  
Bovine Mammary Epithelial Cells ◽  
Gene And Protein Expression

Abstract The ghrelin peptides were found to circulate in two major forms: acylated ghrelin (AG) and unacylated ghrelin (UAG). Previous studies showed that AG regulates β-casein (CSN2) expression in mammary epithelial cells. However, little is known about the mechanisms by which AG regulates CSN2 gene and protein expression. Evidence suggests that UAG has biological activity through GHSR1a-independent mechanisms. Here, we investigated the possible GHSR1a-mediated effect of UAG on the expression of CSN2 in primary bovine mammary epithelial cells (pbMECs) isolated from lactating cow. We found that both AG and UAG increase the expression of CSN2 in a dose-dependent manner in pbMECs in comparison with the control group. Increased expression of CSN2 was blocked by [D-Lys3]-GHRP-6 (an antagonist of the GHSR1a) and NF449 (a Gs-α subunit inhibitor) in pbMECs. In addition, both AG and UAG activated AKT/protein kinase B (AKT) and extracellular signal-regulated kinase 1/2 (ERK1/2) pathways, whereas [D-Lys3]-GHRP-6 and NF449 inhibited the phosphorylation of AKT and ERK1/2 in pbMECs respectively. Blockade of ERK1/2 and AKT signaling pathways prevented the expression of CSN2 induced by AG or UAG. Finally, we found that both AG and UAG cause cell proliferation through identical signaling pathways. Taken together, these results demonstrate that both AG and UAG act on ERK1/2 and AKT signaling pathways to facilitate the expression of CSN2 in a GHSR1a-dependent manner.

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