Socorro Islas

Center for Research and Advanced Studies of the National Polytechnic Institute

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Lorenza González–Mariscal

Center for Research and Advanced Studies of the National Polytechnic Institute

AÁ

Antonia Ávila‐Flores

Centro Nacional de Biotecnología

Erika P. Rendón‐Huerta

Universidad Nacional Autónoma de México

Martha Robles‐Flores

Universidad Nacional Autónoma de México

Abigail Betanzos

Center for Research and Advanced Studies of the National Polytechnic Institute

José L. Reyes

University of Santo Tomas Hospital

Lissette Ponce

Center for Research and Advanced Studies of the National Polytechnic Institute

Lourdes Alarcón

Universitat Autònoma de Barcelona

Jesús Vega

Center for Research and Advanced Studies of the National Polytechnic Institute

J.A. Caminero Luna

Hospital Universitario de Gran Canaria Doctor Negrín

Cooperative Institutions

Center for Research and Advanced Studies of the National Polytechnic Institute

Instituto Politécnico Nacional

Universidad Nacional Autónoma de México

Centro de Investigación en Materiales Avanzados

Instituto de Estudios Avanzados

Université Côte d'Azur

Centre National de la Recherche Scientifique

Hospital Infantil de México Federico Gómez

Instituto Nacional de Cardiología

Tecnológico Nacional de México

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Tight-junction protein zonula occludens 2 is a target of phosphorylation by protein kinase C

Biochemical Journal (2001)

Antonia Ávila‐Flores Erika P. Rendón‐Huerta Jacqueline Moreno Socorro Islas Abigail Betanzos

Zonula occludens 2 (ZO-2) protein is a tight-junction phos phorylated protein that belongs to the membrane-associated guanylate kinase (‘MAGUK’) family. Here we study the interaction between ZO-2 and protein kinase C (PKC). We have constructed two ZO-2 fusion proteins of the middle (3PSG) and C-terminal (AP) regions of the molecule and demonstrate that they are phosphorylated by PKC isoenzymes β, ∊, λ and ∊. To understand the physiological significance of the interaction between ZO-2 and PKC, we analysed the phosphorylation state of ZO-2 immunoprecipitated from monolayers with mature tight junctions or from cells that either lack them or have them disassembled through Ca2+ chelation. We found that in the latter condition the phosphorylation level of ZO-2 is significantly higher and is due to the action of both PKC and cAMP-dependent protein kinase. These results therefore suggest that the phosphorylated state of ZO-2 restrains its capacity to operate at the junctional complex.

Immunoprecipitation

10.1042/bj3600295

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Citations (51)

Zona Occludens-2 Inhibits Cyclin D1 Expression and Cell Proliferation and Exhibits Changes in Localization along the Cell Cycle

Molecular Biology of the Cell (2008)

Rocío Tapia Miriam Huerta Socorro Islas Antonia Ávila‐Flores Esther López‐Bayghen

Here, we have studied the effect of the tight junction protein zona occludens (ZO)-2 on cyclin D1 (CD1) protein expression. CD1 is essential for cell progression through the G1 phase of the cell cycle. We have found that in cultures of synchronized Madin-Darby canine kidney cells, ZO-2 inhibits cell proliferation at G0/G1 and decreases CD1 protein level. These effects occur in response to a diminished CD1 translation and an augmented CD1 degradation at the proteosome triggered by ZO-2. ZO-2 overexpression decreases the amount of Glycogen synthase kinase-3beta phosphorylated at Ser9 and represses beta-catenin target gene expression. We have also explored the expression of ZO-2 through the cell cycle and demonstrate that ZO-2 enters the nucleus at the late G1 phase and leaves the nucleus when the cell is in mitosis. These results thus explain why in confluent quiescent epithelia ZO-2 is absent from the nucleus and localizes at the cellular borders, whereas in sparse proliferating cultures ZO-2 is conspicuously present at the nucleus.

Cyclin A

10.1091/mbc.e08-03-0277

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Citations (79)

Localization and Release of 5-Hydroxytryptamine in the Crayfish Eyestalk

Journal of Experimental Biology (1997)

Leonardo Rodrı́guez-Sosa Arturo Picones Gabina Calderón Rosete Socorro Islas Hugo Aréchigá

The content and regional distribution of 5-hydroxytryptamine (5-HT) in the crayfish eyestalk was determined by high-performance liquid chromatography. Levels of the 5-HT precursors l-tryptophan (L-TRP) and 5-hydroxytryptophan (5-OH-TRP), and of three metabolites, 5-hydroxytryptophol (5-HTPH), N-acetylserotonin (NA-5-HT) and 5-hydroxy-indole-3-acetic acid (5-HIAA), were also determined. The total content of 5-HT in the eyestalk was 95.4+/-49.3 pg mg-1 wet mass (mean +/- s.d., N=55) while the specific content was 9.6+/-4.9 fmol microg-1 protein (mean +/- s.d. N=5). 5-HT was present in all four ganglia of the eyestalk. The highest proportion was found in the medulla terminalis (40.2 %) and the lowest in the retina lamina ganglionaris (9.9 %), which also had the lowest specific content. Conversely, the highest specific content of L-TRP was in the retina lamina ganglionaris. 5-HT biosynthesis and metabolism were explored in isolated eyestalks. The monoamine oxidase blocker pargyline, at concentrations between 0.8 and 10 mmol l-1, elicited a dose-dependent increase in 5-HT content. The biosynthesis of 5-HT in the crayfish eyestalk is suggested by the presence of its immediate precursor (5-OH-TRP) and by the suppression of 5-HT synthesis induced by m-hydroxybenzyl-hydrazine (m-HBH), a blocker of 5-OH-TRP decarboxylase. The presence of immunopositive cell bodies and axons was demonstrated using an anti-5-HT antiserum. 5-HT-like immunopositivity was detected in various regions of the eyestalk. Efferent immunopositive axons were also identified in the optic nerve, and these may have originated in the protocerebral lobe of the supraoesophageal ganglion. The branchings of these axons were profusely distributed in the neuropile of the medulla terminalis. A basal level release of 5-HT was detected in isolated eyestalks. The amount recovered was increased two-to threefold after blocking 5-HT uptake with fluoxetine (1 micromol l-1). Incubation of eyestalks in solutions containing a high K+ concentration (80 mmol l-1) released 5-HT. Electrical stimulation of the optic nerve released 5-HT as a function of the intensity of stimulation. Both the basal and evoked release were suppressed by lowering the Ca2+ concentration in the medium. These observations support a role for 5-HT as a neurotransmitter or neuromodulator in the crayfish eyestalk.

Eyestalk

Pargyline

Tryptophan hydroxylase

10.1242/jeb.200.23.3067

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Citations (37)

Molecular Characterization of the Tight Junction Protein ZO-1 in MDCK Cells

Experimental Cell Research (1999)

Lorenza González–Mariscal Socorro Islas R. Contreras Refugio García‐Villegas Abigail Betanzos

10.1006/excr.1999.4392

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Citations (50)

CRTAM: A molecule involved in epithelial cell adhesion

Journal of Cellular Biochemistry (2010)

Erika Garay Genaro Patiño‐López Socorro Islas Lourdes Alarcón Elsy B. Canché-Pool

Abstract C lass I‐ r estricted T cell a ssociated m olecule (CRTAM) is a member of the immunoglobulin superfamily that complies with the structural characteristics of the JAM family of proteins and is phylogenetically more closely related to nectin‐like proteins. Here we demonstrate for the first time, that CRTAM is expressed in epithelial cells along the lateral membrane and is important for early cell–cell contacts and cell–substrate interactions. CRTAM is sensitive to intermediate filament disruption and treatment of monolayers with soluble CRTAM enhances cell–cell dissociation and lowers transepithelial electrical resistance. Incubation of newly plated cells with anti‐CRTAM antibody decreases the formation of cell aggregates and promotes cell detachment. Co‐cultures of epithelial cells and fibroblasts that lack CRTAM expression and in vitro binding assays, demonstrate the participation of CRTAM in homotypic and heterotypic trans ‐interactions. Hence we conclude that CRTAM is a molecule involved in epithelial cell adhesion. J. Cell. Biochem. 111: 111–122, 2010. © 2010 Wiley‐Liss, Inc.

Immunoglobulin superfamily

Cell–cell interaction

Cell membrane

Nectin

Cell type

10.1002/jcb.22673

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Citations (22)

Nuclear Localization of the Tight Junction Protein ZO-2 in Epithelial Cells

Experimental Cell Research (2002)

Socorro Islas Jesús Vega Lissette Ponce Lorenza González–Mariscal

Septate junctions

Nuclear pore

Nuclear export signal

Paracellular transport

10.1006/excr.2001.5457

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Citations (184)

p32 (gC1qBP) Is a General Protein Kinase C (PKC)-binding Protein

Journal of Biological Chemistry (2002)

Martha Robles‐Flores Erika P. Rendón‐Huerta Héctor González-Aguilar Guillermo Mendoza‐Hernández Socorro Islas

The aim of this study was to identify cellular proteins that bind protein kinase C (PKC) and may influence its activity and its localization. A 32-kDa PKC-binding protein was purified to homogeneity from the Triton X-100-insoluble fraction obtained from hepatocytes homogenates. The protein was identified by NH₂-terminal amino acid sequencing as the previously described mature form of p32 (gC1qR). Recombinant p32 was expressed as a glutathione S-transferase fusion protein, affinity-purified, and tested for an in vitro interaction with PKC using an overlay assay approach. All PKC isoforms expressed in rat hepatocytes interacted in vitro with p32, but the binding dependence on PKC activators was different for each one. Whereas PKCδ only binds to p32 in the presence of PKC activators, PKCζ and PKCα increase their binding when they are in the activated form. Other PKC isoforms such as β, ε, and θ bind equally well to p32 regardless of the presence of PKC activators, and PKCμ binds even better in their absence. It was also found that p32 is not a substrate for any of the PKC isoforms tested, but interestingly, its presence had a stimulatory effect (2-fold for PKCδ) on PKC activity. We also observed in vivo interaction between PKC and p32 by immunofluorescence and confocal microscopy. A time course of phorbol ester treatment of cultured rat hepatocytes (C9 cells) showed that PKCθ and p32 are constitutively associated in vivo, whereas PKCδ activation is required for its association with p32. Our data also showed that phorbol ester treatment induces a transient translocation of p32 from the cytoplasm to the cell nucleus. Together, these findings suggest that p32 may be a regulator of PKC location and function.

10.1074/jbc.m109333200

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Citations (69)

Vinculin but not α-actinin is a target of PKC phosphorylation during junctional assembly induced by calcium

Journal of Cell Science (1998)

Mirna Pérez‐Moreno Antonia Ávila‐Flores Socorro Islas Sandrine Sanchez Lorenza González–Mariscal

ABSTRACT The establishment of the junctional complex in epithelial cells requires the presence of extracellular calcium, and is controlled by a network of reactions involving G-proteins, phospholipase C and protein kinase C. Since potential candidates for phosphorylation are the tight junction associated proteins ZO1, ZO2 and ZO3, in a previous work we specifically explored these molecules but found no alteration in their phosphorylation pattern. To continue the search for the target of protein kinase C, in the present work we have studied the subcellular distribution and phosphorylation of vinculin and α-actinin, two actin binding proteins of the adherent junctions. We found that during the junctional sealing induced by Ca2+, both proteins move towards the cell periphery and, while there is a significant increase in the phosphorylation of vinculin, α-actinin remains unchanged. The increased phosphorylation of vinculin is due to changes in phosphoserine and phosphothreonine content and seems to be regulated by protein kinase C, since: (1) DiC8 (a kinase C stimulator) added to monolayers cultured without calcium significantly increases the vinculin phosphorylation level; (2) H7 and calphostin C (both protein kinase C inhibitors) completely abolish this increase during a calcium switch; (3) inhibition of phosphorylation during a calcium switch blocks the subcellular redistribution of vinculin and α-actinin. These results therefore suggest that vinculin phosphorylation by protein kinase C is a crucial step in the correct assembly of the epithelial junctional complex.

Vinculin

Phosphoserine

10.1242/jcs.111.23.3563

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Citations (56)

Tight-junction protein zonula occludens 2 is a target of phosphorylation by protein kinase C

Biochemical Journal (2001)

Antonia Ávila‐Flores Erika P. Rendón‐Huerta Jacqueline Moreno Socorro Islas Abigail Betanzos

Immunoprecipitation

10.1042/0264-6021:3600295

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Citations (73)