scholarly journals Accumulation of a microtubule-binding protein, pp170, at desmosomal plaques

1992 ◽  
Vol 117 (4) ◽  
pp. 813-824 ◽  
Author(s):  
IU Wacker ◽  
JE Rickard ◽  
JR De Mey ◽  
TE Kreis
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Polarity ◽  
Mdck Cells ◽  
Binding Protein ◽  
Cell Junction ◽  
Microtubule Binding ◽  
Epithelial Cell Polarity ◽  
Junction Formation ◽  
Cell Cell

The establishment of epithelial cell polarity correlates with the formation of specialized cell-cell junctions and striking changes in the organization of microtubules. A significant fraction of the microtubules in MDCK cells become stabilized, noncentrosomally organized, and arranged in longitudinal bundles in the apical-basal axis. This correlation suggests a functional link between cell-cell junction formation and control of microtubule organization. We have followed the distribution of pp170, a recently described microtubule-binding protein, during establishment of epithelial cell polarity. This protein shows the typical patchy distribution along microtubules in subconfluent fibroblasts and epithelial cells, often associated with the peripheral ends of a subpopulation of microtubules. In contrast to its localization in confluent fibroblasts (A72) and HeLa cells, however, pp170 accumulates in patches delineating the regions of cell-cell contacts in confluent polarizing epithelial cells (MDCK and Caco-2). Double immunolocalization with antibodies specific for cell-cell junction proteins, confocal microscopy, and immunoelectron microscopy on polarized MDCK cells suggest that pp170 accumulates at desmosomal plaques. Furthermore, microtubules and desmosomes are found in close contact. Maintenance of the desmosomal association of pp170 is dependent on intact microtubules in 3-d-old, but not in 1-d-old MDCK cell cultures. This suggests a regulated interaction between microtubules and desmosomes and a role for pp170 in the control of changes in the properties of microtubules induced by epithelial cell-cell junction formation.

Epithelial cell polarity and hypoxia influence heme oxygenase-1 expression by heme in renal epithelial cells

2006 ◽  
Vol 291 (4) ◽  
pp. F790-F795 ◽  
Author(s):  
Mahesh Basireddy ◽  
Jason T. Lindsay ◽  
Anupam Agarwal ◽  
Daniel F. Balkovetz
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Surface ◽  
Cell Polarity ◽  
Heme Oxygenase ◽  
Mdck Cells ◽  
Heme Oxygenase 1 ◽  
Renal Tubules ◽  
Epithelial Cell Polarity ◽  
Surface Sensitivity

Induction of heme oxygenase-1 (HO-1) in renal tubules occurs as an adaptive and beneficial response in acute renal failure (ARF) following ischemia and nephrotoxins. Using an in vitro model of polarized Madin-Darby canine kidney (MDCK) epithelial cells, we examined apical and basolateral cell surface sensitivity to HO-1 induction by heme. Basolateral exposure to 5 μM hemin (heme chloride) resulted in higher HO-1 induction than did apical exposure. The peak induction of HO-1 by basolateral application of hemin occurred between 12 and 18 h of exposure and was dose dependent. Similar cell surface sensitivity to hemin-induced HO-1 expression was observed using a mouse cortical collecting duct cell line (94D cells). Hepatocyte growth factor (HGF) is known to decrease cell polarity of MDCK cells. Following pretreatment with HGF, apically applied hemin gave greater stimulation of HO-1 expression, whereas HGF alone did not induce HO-1. We also examined the effect of hypoxia on hemin-mediated HO-1 induction. MDCK cells were subjected to hypoxia (1% O2) for 24 h to simulate the effects of ischemic ARF. Under hypoxic conditions, both apical as well as basolateral surfaces of MDCK were more sensitive to HO-1 induction by hemin. Hypoxia alone did not induce HO-1 but appeared to potentiate both apical and basolateral sensitivity to hemin-mediated induction. These data demonstrate that the induction of HO-1 expression in polarized renal epithelia by heme is achieved primarily via basolateral exposure. However, under conditions of altered renal epithelial cell polarity and hypoxia, increased HO-1 induction occurs following apical exposure to heme.

scholarly journals Shank2 Binds to aPKC and Controls Tight Junction Formation with Rap1 Signaling during Establishment of Epithelial Cell Polarity

Cell Reports ◽  
2020 ◽  
Vol 31 (1) ◽  
pp. 107407
Author(s):  
Kazunori Sasaki ◽  
Noriko Kojitani ◽  
Hiroko Hirose ◽  
Yohei Yoshihama ◽  
Hidefumi Suzuki ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Tight Junction ◽  
Cell Polarity ◽  
Epithelial Cell Polarity ◽  
Tight Junction Formation ◽  
Junction Formation

scholarly journals Move your microvilli

2014 ◽  
Vol 207 (1) ◽  
pp. 9-11 ◽  
Author(s):  
Robert S. Fischer
Keyword(s):  
Wound Healing ◽  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Polarity ◽  
Apical Membrane ◽  
Apical Surface ◽  
Epithelial Cell Polarity ◽  
Cell Biol ◽  
Polarized Epithelial Cells

Polarized epithelial cells create tightly packed arrays of microvilli in their apical membrane, but the fate of these microvilli is relatively unknown when epithelial cell polarity is lost during wound healing. In this issue, Klingner et al. (2014. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201402037) show that, when epithelial cells become subconfluent, actomyosin contractions locally within the apical cortex cause their microvilli to become motile over the dorsal/apical surface. Their unexpected observations may have implications for epithelial responses in wound healing and disease.

scholarly journals Hydrolysis of Epithelial Junctional Proteins by Porphyromonas gingivalis Gingipains

2002 ◽  
Vol 70 (5) ◽  
pp. 2512-2518 ◽  
Author(s):  
Jannet Katz ◽  
Qiu-Bo Yang ◽  
Ping Zhang ◽  
Jan Potempa ◽  
James Travis ◽  
...  
Keyword(s):  
Epithelial Cell ◽  
Porphyromonas Gingivalis ◽  
Catalytic Domain ◽  
Mdck Cells ◽  
Adherens Junction ◽  
Cell Junction ◽  
Critical Threshold ◽  
Hydrolysis Of ◽  
E Cadherin ◽  
Cell Cell

ABSTRACT Porphyromonas gingivalis has been implicated as an etiologic agent of adult periodontitis. We have previously shown that P. gingivalis can degrade the epithelial cell-cell junction complexes, thus suggesting that this bacterium can invade the underlying connective tissues via a paracellular pathway. However, the precise mechanism(s) involved in this process has not been elucidated. The purpose of this study was to determine if the arginine- and lysine-specific gingipains of P. gingivalis (i.e., HRgpA and RgpB, and Kgp, respectively) were responsible for the degradation of E-cadherin, the cell-cell adhesion protein in the adherens junctions. In addition, we compared the degradative abilities of the whole gingipains HRgpA and Kgp to those of their catalytic domains alone. In these studies, immunoprecipitated E-cadherin as well as monolayers of polarized Madin-Darby canine kidney (MDCK) epithelial cell cultures were incubated with the gingipains and hydrolysis of E-cadherin was assessed by Western blot analysis. Incubation of P. gingivalis cells with immunoprecipitated E-cadherin resulted in degradation, whereas prior exposure of P. gingivalis cells to leupeptin and especially acetyl-Leu-Val-Lys-aldehyde (which are arginine- and lysine-specific inhibitors, respectively) reduced this activity. Furthermore, incubation of E-cadherin immunoprecipitates with the different gingipains resulted in an effective and similar hydrolysis of the protein. However, when monolayers of MDCK cells were exposed to the gingipains, Kgp was most effective in hydrolyzing the E-cadherin molecules in the adherens junction. Kgp was more effective than its catalytic domain in degrading E-cadherin at 500 nM but not at a lower concentration (250 nM). These results suggest that the hemagglutinin domain of Kgp plays a role in degradation and that there is a critical threshold concentration for this activity. Taken together, these results provide evidence that the gingipains, especially Kgp, are involved in the degradation of the adherens junction of epithelial cells, which may be important in the invasion of periodontal connective tissue by P. gingivalis.

scholarly journals PLEKHG4B enables actin cytoskeletal remodeling during epithelial cell-cell junction formation

2020 ◽  
pp. jcs.249078
Author(s):  
Komaki Ninomiya ◽  
Kai Ohta ◽  
Kazunari Yamashita ◽  
Kensaku Mizuno ◽  
Kazumasa Ohashi
Keyword(s):  
Epithelial Cell ◽  
A549 Cells ◽  
Cell Junctions ◽  
Cell Junction ◽  
Nucleotide Exchange ◽  
Actin Bundles ◽  
Rhoa Activity ◽  
Cytoskeletal Remodeling ◽  
Junction Formation ◽  
Cell Cell

Cell-cell junction formation requires actin cytoskeletal remodeling. Here we show that PLEKHG4B, a Rho-guanine nucleotide exchange factor (Rho-GEF), plays a crucial role in epithelial cell-cell junction formation. Knockdown of PLEKHG4B decreased Cdc42 activity and tended to increase RhoA activity in A549 cells. A549 monolayer cells showed 'closed junctions' with closely packed actin bundles along the cell-cell contacts, but PLEKHG4B knockdown suppressed closed junction formation and exhibited 'open junctions' with split actin bundles located away from the cell-cell boundary. In calcium-switch assays, PLEKHG4B knockdown delayed the conversion of open junctions to closed junctions and β-catenin accumulation at cell-cell junctions. Further, PLEKHG4B knockdown abrogated the reduction in myosin activity normally seen in the later stage of junction formation. The aberrant myosin activation and impairments in closed junction formation in PLEKHG4B-knockdown cells were reverted by ROCK inhibition or LARG/PDZ-RhoGEF knockdown. These results suggest that PLEKHG4B enables actin remodeling during epithelial cell-cell junction maturation, probably by reducing myosin activity in the later stage of junction formation, through suppressing LARG/PDZ-RhoGEF and RhoA-ROCK activities. We also showed that annexin-A2 participates in PLEKHG4B localization to cell-cell junctions.

Epithelial cell polarity: what flies can teach us about cancer

2012 ◽  
Vol 53 ◽  
pp. 129-140 ◽  
Author(s):  
Daniel T. Bergstralh ◽  
Daniel St Johnston
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Polarity ◽  
Human Cancer ◽  
Fruit Fly ◽  
Model Organisms ◽  
Epithelial Cell Polarity ◽  
Energetic Stress ◽  
Evolutionarily Conserved ◽  
Cellular Machinery

Epithelial cells are polarized along their apical–basal axis. Much of the cellular machinery that goes into establishing and maintaining epithelial cell polarity is evolutionarily conserved. Model organisms, including the fruit fly, Drosophila melanogaster, are thus particularly useful for the study of cell polarity. Work in Drosophila has identified several important components of the polarity machinery and has also established the surprising existence of a secondary cell polarity pathway required only under conditions of energetic stress. This work has important implications for the understanding of human cancer. Most cancers are epithelial in origin, and the loss of cell polarity is a critical step towards malignancy. Thus a better understanding of how polarity is established and maintained in epithelial cells will help us to understand the process of malignant transformation and may lead to improved therapies. In the present chapter we discuss the current understanding of how epithelial cell polarity is regulated and the known associations between polarity factors and cancer.

scholarly journals Nectin proteins are expressed at early stages of nephrogenesis and play a role in renal epithelial cell morphogenesis

2009 ◽  
Vol 296 (3) ◽  
pp. F564-F574 ◽  
Author(s):  
Paul R. Brakeman ◽  
Kathleen D. Liu ◽  
Kazuya Shimizu ◽  
Yoshimi Takai ◽  
Keith E. Mostov
Keyword(s):  
Epithelial Cell ◽  
Epithelial Cells ◽  
Cell Polarity ◽  
Mdck Cells ◽  
Three Dimensional ◽  
Dominant Negative ◽  
Cell Morphogenesis ◽  
Renal Epithelial Cell ◽  
Normal Epithelial Cell ◽  
Three Dimensional Culture

Development of the nephron requires conversion of the metanephric mesenchyme into tubular epithelial structures with specifically organized intercellular junctions. The nectin proteins are a family of transmembrane proteins that dimerize to form intercellular junctional complexes between epithelial cells. In this study, we demonstrate that nectin junctions appear during the earliest stages of epithelial cell morphogenesis in the murine nephron concurrently with the transition of mesenchymal cells into epithelial cells. We have defined the role of nectin during epithelial cell morphogenesis by studying nectin in a three-dimensional culture of Madin-Darby canine kidney (MDCK) cells. In a three-dimensional culture of MDCK cells grown in purified type 1 collagen, expression of a dominant negative form of nectin causes disruption of the formation of cell polarity and disruption of tight junction (TJ) formation, as measured by zonula occludens-1 (ZO-1) localization. In MDCK cells cultured in Matrigel, exogenous expression of nectin-1 causes disruption of normal epithelial cell cyst formation and decreased apoptosis. These data demonstrate that nectins play an important role in normal epithelial cell morphogenesis and may play a role in mesenchymal-to-epithelial transition during nephrogenesis by providing an antiapoptotic signal and promoting the formation of TJs and cell polarity.

scholarly journals The MAGUK Protein MPP7 Binds to the Polarity Protein hDlg1 and Facilitates Epithelial Tight Junction Formation

2007 ◽  
Vol 18 (5) ◽  
pp. 1744-1755 ◽  
Author(s):  
Volker M. Stucke ◽  
Evy Timmerman ◽  
Joel Vandekerckhove ◽  
Kris Gevaert ◽  
Alan Hall
Keyword(s):  
Epithelial Cell ◽  
Tight Junction ◽  
Tight Junctions ◽  
Cell Polarity ◽  
Functional Organization ◽  
Epithelial Cell Polarity ◽  
Tight Junction Formation ◽  
Evolutionarily Conserved ◽  
Junction Formation ◽  
Epithelial Tight Junction

Three groups of evolutionarily conserved proteins have been implicated in the establishment of epithelial cell polarity: the apically-localized proteins of the Par (Par3-Par6-aPKC-Cdc42) and Crumbs groups (Crb3-PALS1-PATJ) and the basolaterally localized proteins of the Dlg group (Dlg1-Scribble-Lgl). During epithelial morphogenesis, these proteins participate in a complex network of interdependent interactions that define the position and functional organization of adherens junctions and tight junctions. However, the biochemical pathways through which they control polarity are poorly understood. In this study, we identify an interaction between endogenous hDlg1 and MPP7, a previously uncharacterized MAGUK-p55 subfamily member. We find that MPP7 targets to the lateral surface of epithelial cells via its L27N domain, through an interaction with hDlg1. Loss of either hDlg1 or MPP7 from epithelial Caco-2 cells results in a significant defect in the assembly and maintenance of functional tight junctions. We conclude that the formation of a complex between hDlg1 and MPP7 promotes epithelial cell polarity and tight junction formation.

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