scholarly journals Rho/Rho-associated Kinase-II Signaling Mediates Disassembly of Epithelial Apical Junctions

2007 ◽  
Vol 18 (9) ◽  
pp. 3429-3439 ◽  
Author(s):  
Stanislav N. Samarin ◽  
Andrei I. Ivanov ◽  
Gilles Flatau ◽  
Charles A. Parkos ◽  
Asma Nusrat
Keyword(s):  
Epithelial Cells ◽  
Rho Gtpase ◽  
Critical Role ◽  
Junctional Complex ◽  
Nucleotide Exchange ◽  
Calcium Depletion ◽  
Pharmacological Inhibition ◽  
Apical Junctional Complex ◽  
Apical Junctions

Apical junctional complex (AJC) plays a vital role in regulation of epithelial barrier function. Disassembly of the AJC is observed in diverse physiological and pathological states; however, mechanisms governing this process are not well understood. We previously reported that the AJC disassembly is driven by the formation of apical contractile acto-myosin rings. In the present study, we analyzed the signaling pathways regulating acto-myosin–dependent disruption of AJC by using a model of extracellular calcium depletion. Pharmacological inhibition analysis revealed a critical role of Rho-associated kinase (ROCK) in AJC disassembly in calcium-depleted epithelial cells. Furthermore, small interfering RNA (siRNA)-mediated knockdown of ROCK-II, but not ROCK-I, attenuated the disruption of the AJC. Interestingly, AJC disassembly was not dependent on myosin light chain kinase and myosin phosphatase. Calcium depletion resulted in activation of Rho GTPase and transient colocalization of Rho with internalized AJC proteins. Pharmacological inhibition of Rho prevented AJC disassembly. Additionally, Rho guanine nucleotide exchange factor (GEF)-H1 translocated to contractile F-actin rings after calcium depletion, and siRNA-mediated depletion of GEF-H1 inhibited AJC disassembly. Thus, our findings demonstrate a central role of the GEF-H1/Rho/ROCK-II signaling pathway in the disassembly of AJC in epithelial cells.

scholarly journals Mammary gland adipocytes in lactation cycle, obesity and breast cancer

2021 ◽  
Author(s):  
Georgia Colleluori ◽  
Jessica Perugini ◽  
Giorgio Barbatelli ◽  
Saverio Cinti
Keyword(s):  
Breast Cancer ◽  
Mammary Gland ◽  
Epithelial Cells ◽  
Close Association ◽  
Critical Role ◽  
Exocrine Gland ◽  
Plastic Properties ◽  
Lactation Cycle ◽  
Gland Development

AbstractThe mammary gland (MG) is an exocrine gland present in female mammals responsible for the production and secretion of milk during the process of lactation. It is mainly composed by epithelial cells and adipocytes. Among the features that make the MG unique there are 1) its highly plastic properties displayed during pregnancy, lactation and involution (all steps belonging to the lactation cycle) and 2) its requirement to grow in close association with adipocytes which are absolutely necessary to ensure MG’s proper development at puberty and remodeling during the lactation cycle. Although MG adipocytes play such a critical role for the gland development, most of the studies have focused on its epithelial component only, leaving the role of the neighboring adipocytes largely unexplored. In this review we aim to describe evidences regarding MG’s adipocytes role and properties in physiologic conditions (gland development and lactation cycle), obesity and breast cancer, emphasizing the existing gaps in the literature which deserve further investigation.

scholarly journals Paracrine interactions between epithelial cells promote colon cancer growth

2020 ◽  
Author(s):  
Guillaume Jacquemin ◽  
Annabelle Wurmser ◽  
Mathilde Huyghe ◽  
Wenjie Sun ◽  
Meghan Perkins ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cancer Cells ◽  
Stromal Cells ◽  
Critical Role ◽  
Essential Factor ◽  
Transcriptional Responses ◽  
Tumour Formation ◽  
Different Types ◽  
The Impact

AbstractTumours are complex ecosystems composed of different types of cells that communicate and influence each other. While the critical role of stromal cells in affecting tumour growth is well established, the impact of mutant cancer cells on healthy surrounding tissues remains poorly defined. Here, we uncovered a paracrine mechanism by which intestinal cancer cells reactivate foetal and regenerative Yap-associated transcriptional programs in neighbouring wildtype epithelial cells, rendering them adapted to thrive in the tumour context. We identified the glycoprotein Thrombospondin-1 (Thbs1) as the essential factor that mediates non-cell autonomous morphological and transcriptional responses. Importantly, Thbs1 is associated with bad prognosis in several human cancers. This study reveals the Thbs1-YAP axis as the mechanistic link mediating paracrine interactions between epithelial cells, promoting tumour formation and progression.

Sodium coupled neutral amino acid transporter SNAT2 counteracts cardiogenic pulmonary edema by driving alveolar fluid clearance

2021 ◽  
Author(s):  
Sarah Weidenfeld ◽  
Cécile Chupin ◽  
Delia Isabel Langner ◽  
Tamador Zetoun ◽  
Simon Rozowsky ◽  
...  
Keyword(s):  
Amino Acid ◽  
Epithelial Cells ◽  
Pulmonary Edema ◽  
Hydrostatic Stress ◽  
Critical Role ◽  
Neutral Amino Acid ◽  
Lung Edema ◽  
Alveolar Fluid Clearance ◽  
Pharmacological Inhibition ◽  
Pulmonary Epithelial Cells

The constant transport of ions across the alveolar epithelial barrier regulates alveolar fluid homeostasis. Dysregulation or inhibition of Na+ transport causes fluid accumulation in the distal airspaces resulting in impaired gas exchange and respiratory failure. Previous studies have primarily focused on the critical role of amiloride-sensitive epithelial sodium channel (ENaC) in alveolar fluid clearance (AFC), yet activation of ENaC failed to attenuate pulmonary edema in clinical trials. Since 40% of AFC is amiloride-insensitive, Na+ channels/transporters other than ENaC such as Na+-coupled neutral amino acid transporters (SNATs) may provide novel therapeutic targets. Here, we identified a key role for SNAT2 (SLC38A2) in AFC and pulmonary edema resolution. In isolated perfused mouse and rat lungs, pharmacological inhibition of SNATs by HgCl2 and α-methylaminoisobutyric acid (MeAIB) impaired AFC. Quantitative RT-PCR identified SNAT2 as highest expressed System A transporter in pulmonary epithelial cells. Pharmacological inhibition or siRNA-mediated knockdown of SNAT2 reduced transport of L-alanine across pulmonary epithelial cells. Homozygous Slc38a2-/- mice were subviable and died shortly after birth with severe cyanosis. Isolated lungs of Slc38a2+/- mice developed higher wet-to-dry weight ratios (W/D) as compared to WT in response to hydrostatic stress. Similarly, W/D ratios were increased in Slc38a2+/- mice as compared to controls in an acid-induced lung injury model. Our results identify SNAT2 as functional transporter for Na+ and neutral amino acids in pulmonary epithelial cells with a relevant role in AFC and the resolution of lung edema. Activation of SNAT2 may provide a new therapeutic strategy to counteract and/or reverse pulmonary edema.

scholarly journals Transcriptional and Ultrastructural Analyses Suggest Novel Insights into Epithelial Barrier Impairment in Celiac Disease

Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 516
Author(s):  
Agnieszka Sowińska ◽  
Yasser Morsy ◽  
Elżbieta Czarnowska ◽  
Beata Oralewska ◽  
Ewa Konopka ◽  
...  
Keyword(s):  
Celiac Disease ◽  
Epithelial Cells ◽  
Intestinal Permeability ◽  
Transcriptional Analysis ◽  
Junctional Complex ◽  
Sequencing Data ◽  
Ultrastructural Studies ◽  
Extracellular Region ◽  
Significant Gene

Disruption of epithelial junctional complex (EJC), especially tight junctions (TJ), resulting in increased intestinal permeability, is supposed to activate the enhanced immune response to gluten and to induce the development of celiac disease (CD). This study is aimed to present the role of EJC in CD pathogenesis. To analyze differentially expressed genes the next-generation mRNA sequencing data from CD326+ epithelial cells isolated from non-celiac and celiac patients were involved. Ultrastructural studies with morphometry of EJC were done in potential CD, newly recognized active CD, and non-celiac controls. The transcriptional analysis suggested disturbances of epithelium and the most significant gene ontology enriched terms in epithelial cells from CD patients related to the plasma membrane, extracellular exome, extracellular region, and extracellular space. Ultrastructural analyses showed significantly tighter TJ, anomalies in desmosomes, dilatations of intercellular space, and shorter microvilli in potential and active CD compared to controls. Enterocytes of fetal-like type and significantly wider adherence junctions were observed only in active CD. In conclusion, the results do not support the hypothesis that an increased passage of gluten peptides by unsealing TJ precedes CD development. However, increased intestinal permeability due to abnormality of epithelium might play a role in CD onset.

scholarly journals P023 Identification of regulated mechanistic pathways and genes to protect intestinal barrier injury by larazotide acetate in an IBD microenvironment

2020 ◽  
Vol 14 (Supplement_1) ◽  
pp. S142-S143
Author(s):  
Y Jin ◽  
J Madan ◽  
K Radha B ◽  
B Anthony
Keyword(s):  
Rho Gtpase ◽  
Differentially Expressed ◽  
Mucosal Barrier ◽  
Signalling Pathways ◽  
Junctional Complex ◽  
Pathway Enrichment Analysis ◽  
Regulatory Pathways ◽  
Apical Junctional Complex ◽  
Anoxic Injury ◽  
In Cells

Abstract Background Inflammatory bowel disease (IBD) is due to a combination of factors, including genetics, mucosal barrier dysfunction and dysregulated immune responses. Recently, it has been appreciated that IBD is associated with profound tissue anoxia. Tight junctions (TJs) located at the apical lateral region of adjacent intestinal epithelial cells are largely responsible for regulating the intestinal mucosal barrier. Larazotide acetate (LA, Innovate Biopharmaceuticals, Inc., Raleigh, NC) is a synthetic, eight amino acid peptide that is known to act as a TJ regulator capable of closing ‘leaky’ interepithelial junctions. Presently, LA is being studied in Phase 3 clinical trials for the treatment of celiac disease. Based on prior work in our lab, we hypothesised that LA would protect the TJ barrier in an anoxic injury IBD model associated with upregulation of TJ-associated signalling pathways. Methods C2BBe1 (Caco-2 brush border expressing) monolayers were treated apically with LA and were subjected to anoxia for 2 h followed by reoxygenation with 21% O2. Barrier function was assessed by measuring transepithelial electrical resistance (TEER) during anoxic injury and recovery. TJ proteins and cytoskeleton protein F-actin were assessed by western blotting and immunofluorescence microscopy. Then, next-generation RNA sequencing was employed to assess cellular regulatory pathways. Results Pre-treatment of anoxic injured C2BBe1cells with 10 mM LA significantly increased TEER as compared with untreated anoxic injured cells. The TJ protein occludin and ZO-1 were disrupted in anoxia-injured monolayer. Alternatively, treatment with 10 mM LA prevented disruption of TJ proteins during anoxic injury. Gene ontology annotation revealed a number of critical signalling pathways that were differentially expressed in cells treated with LA, including biological processes involved in establishment of cell polarity, molecular functions that regulate junctional structures, and cellular components associated with epithelial repair (cell leading edge, ruffle and apical junctional complex). Furthermore, Ras/Rho GTPase binding and protein serine/threonine kinase activity were differentially expressed in cells treated with LA. Additionally, Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis revealed enrichment of target genes for ‘cell cycle,’ ‘adherens junction’ and ‘Wnt signalling pathways’. Conclusion The results of the present study provide novel insights into the molecular mechanism of action of LA on the protection of TJ integrity in anoxic injury, an IBD microenvironment and the potential for a more broad use in important digestive diseases such as IBD.

scholarly journals MicroRNA Regulation of the Small Rho GTPase Regulators—Complexities and Opportunities in Targeting Cancer Metastasis

Cancers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1092 ◽  
Author(s):  
Brock A. Humphries ◽  
Zhishan Wang ◽  
Chengfeng Yang
Keyword(s):  
Transcriptional Activation ◽  
Rho Gtpases ◽  
Cancer Metastasis ◽  
Rho Gtpase ◽  
Critical Role ◽  
Large Family ◽  
Actin Dynamics ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange

The small Rho GTPases regulate important cellular processes that affect cancer metastasis, such as cell survival and proliferation, actin dynamics, adhesion, migration, invasion and transcriptional activation. The Rho GTPases function as molecular switches cycling between an active GTP-bound and inactive guanosine diphosphate (GDP)-bound conformation. It is known that Rho GTPase activities are mainly regulated by guanine nucleotide exchange factors (RhoGEFs), GTPase-activating proteins (RhoGAPs), GDP dissociation inhibitors (RhoGDIs) and guanine nucleotide exchange modifiers (GEMs). These Rho GTPase regulators are often dysregulated in cancer; however, the underlying mechanisms are not well understood. MicroRNAs (miRNAs), a large family of small non-coding RNAs that negatively regulate protein-coding gene expression, have been shown to play important roles in cancer metastasis. Recent studies showed that miRNAs are capable of directly targeting RhoGAPs, RhoGEFs, and RhoGDIs, and regulate the activities of Rho GTPases. This not only provides new evidence for the critical role of miRNA dysregulation in cancer metastasis, it also reveals novel mechanisms for Rho GTPase regulation. This review summarizes recent exciting findings showing that miRNAs play important roles in regulating Rho GTPase regulators (RhoGEFs, RhoGAPs, RhoGDIs), thus affecting Rho GTPase activities and cancer metastasis. The potential opportunities and challenges for targeting miRNAs and Rho GTPase regulators in treating cancer metastasis are also discussed. A comprehensive list of the currently validated miRNA-targeting of small Rho GTPase regulators is presented as a reference resource.

TGF-β-induced EMT: mechanisms and implications for fibrotic lung disease

2007 ◽  
Vol 293 (3) ◽  
pp. L525-L534 ◽  
Author(s):  
Brigham C. Willis ◽  
Zea Borok
Keyword(s):  
Epithelial Cells ◽  
Lung Disease ◽  
Transforming Growth Factor ◽  
Epithelial Mesenchymal Transition ◽  
Critical Role ◽  
Alveolar Epithelial Cells ◽  
Mesenchymal Transition ◽  
Fibrotic Lung Disease

Epithelial-mesenchymal transition (EMT), a process whereby fully differentiated epithelial cells undergo transition to a mesenchymal phenotype giving rise to fibroblasts and myofibroblasts, is increasingly recognized as playing an important role in repair and scar formation following epithelial injury. The extent to which this process contributes to fibrosis following injury in the lung is a subject of active investigation. Recently, it was demonstrated that transforming growth factor (TGF)-β induces EMT in alveolar epithelial cells (AEC) in vitro and in vivo, and epithelial and mesenchymal markers have been colocalized to hyperplastic type II (AT2) cells in lung tissue from patients with idiopathic pulmonary fibrosis (IPF), suggesting that AEC may exhibit extreme plasticity and serve as a source of fibroblasts and/or myofibroblasts in lung fibrosis. In this review, we describe the characteristic features of EMT and its mechanistic underpinnings. We further describe the contribution of EMT to fibrosis in adult tissues following injury, focusing especially on the critical role of TGF-β and its downstream mediators in this process. Finally, we highlight recent descriptions of EMT in the lung and the potential implications of this process for the treatment of fibrotic lung disease. Treatment for fibrosis of the lung in diseases such as IPF has heretofore focused largely on amelioration of potential inciting processes such as inflammation. It is hoped that this review will stimulate further consideration of the cellular mechanisms of fibrogenesis in the lung and especially the role of the epithelium in this process, potentially leading to innovative avenues of investigation and treatment.

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