scholarly journals Noncentrosomal microtubules and type II myosins potentiate epidermal cell adhesion and barrier formation

2012 ◽  
Vol 199 (3) ◽  
pp. 513-525 ◽  
Author(s):  
Kaelyn D. Sumigray ◽  
Henry P. Foote ◽  
Terry Lechler
Keyword(s):  
Cell Adhesion ◽  
Tight Junction ◽  
Adherens Junctions ◽  
Myosin Ii ◽  
Cell Types ◽  
Cell Junctions ◽  
Cell Cortex ◽  
Dependent Manner ◽  
Cortical Microtubules

During differentiation, many cells reorganize their microtubule cytoskeleton into noncentrosomal arrays. Although these microtubules are likely organized to meet the physiological roles of their tissues, their functions in most cell types remain unexplored. In the epidermis, differentiation induces the reorganization of microtubules to cell–cell junctions in a desmosome-dependent manner. Here, we recapitulate the reorganization of microtubules in cultured epidermal cells. Using this reorganization assay, we show that cortical microtubules recruit myosin II to the cell cortex in order to engage adherens junctions, resulting in an increase in mechanical integrity of the cell sheets. Cortical microtubules and engaged adherens junctions, in turn, increase tight junction function. In vivo, disruption of microtubules or loss of myosin IIA and B resulted in loss of tight junction–mediated barrier activity. We propose that noncentrosomal microtubules act through myosin II recruitment to potentiate cell adhesion in the differentiating epidermis, thus forming a robust mechanical and chemical barrier against the external environment.

scholarly journals Myosin-dependent remodeling of adherens junctions protects junctions from Snail-dependent disassembly

2016 ◽  
Vol 212 (2) ◽  
pp. 219-229 ◽  
Author(s):  
Mo Weng ◽  
Eric Wieschaus
Keyword(s):  
Cell Shape ◽  
Adherens Junctions ◽  
Myosin Ii ◽  
Cell Junctions ◽  
Snail Expression ◽  
Quantitative Image ◽  
Early Expression ◽  
Temporally Correlated ◽  
Shape Changes

Although Snail is essential for disassembly of adherens junctions during epithelial–mesenchymal transitions (EMTs), loss of adherens junctions in Drosophila melanogaster gastrula is delayed until mesoderm is internalized, despite the early expression of Snail in that primordium. By combining live imaging and quantitative image analysis, we track the behavior of E-cadherin–rich junction clusters, demonstrating that in the early stages of gastrulation most subapical clusters in mesoderm not only persist, but move apically and enhance in density and total intensity. All three phenomena depend on myosin II and are temporally correlated with the pulses of actomyosin accumulation that drive initial cell shape changes during gastrulation. When contractile myosin is absent, the normal Snail expression in mesoderm, or ectopic Snail expression in ectoderm, is sufficient to drive early disassembly of junctions. In both cases, junctional disassembly can be blocked by simultaneous induction of myosin contractility. Our findings provide in vivo evidence for mechanosensitivity of cell–cell junctions and imply that myosin-mediated tension can prevent Snail-driven EMT.

scholarly journals Protocadherin 7 localizes to the plasma membrane during mitosis and promotes cytokinesis by a palmitoylation-dependent mechanism

2020 ◽  
Author(s):  
Nazlı Ezgi Özkan-Küçük ◽  
Mohammad Haroon Qureshi ◽  
Berfu Nur Yiğit ◽  
Altuğ Kamacıoğlu ◽  
Nima Bavili ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Membrane Trafficking ◽  
Myosin Ii ◽  
Cell Types ◽  
Mitotic Cell ◽  
Cortical Reorganization ◽  
Cell Cortex ◽  
Cleavage Furrow ◽  
Cytoskeleton Organization ◽  
Dependent Mechanism

ABSTRACTSuccessful cell division requires dramatic reorganization of the cell cortex in coordination with actomyosin cytoskeleton organization, membrane trafficking and cell adhesion. Although the contractile actomyosin ring is considered as hallmark of cytokinesis, in some cell types cell adhesion systems have been shown to drive cytokinesis independently from actomyosin function. We previously reported that Protocadherin 7 (PCDH7) localizes to the mitotic cortex which is required for building up the full mitotic rounding pressure. Here, we show that PCDH7 localizes to the mitotic cell cortex and to the cleavage furrow by a palmitoylation-dependent mechanism. At the cleavage furrow, PCDH7 facilitates the activation of myosin II and successful cytokinesis. Strikingly, PCDH7 promotes cytokinesis even when the myosin II contractility and integrin mediated adhesion are blocked. This work describes a palmitoylation-dependent cortical reorganization which promotes cytokinesis under different conditions.

scholarly journals Paracingulin Regulates the Activity of Rac1 and RhoA GTPases by Recruiting Tiam1 and GEF-H1 to Epithelial Junctions

2008 ◽  
Vol 19 (10) ◽  
pp. 4442-4453 ◽  
Author(s):  
Laurent Guillemot ◽  
Serge Paschoud ◽  
Lionel Jond ◽  
Andrea Foglia ◽  
Sandra Citi
Keyword(s):  
Tight Junction ◽  
Small Gtpases ◽  
Cell Junctions ◽  
Dependent Manner ◽  
Junction Protein ◽  
Junction Formation ◽  
Epithelial Junctions ◽  
Junctional Protein

Small GTPases control key cellular events, including formation of cell–cell junctions and gene expression, and are regulated by activating and inhibiting factors. Here, we characterize the junctional protein paracingulin as a novel regulator of the activity of two small GTPases, Rac1 and RhoA, through the functional interaction with their respective activators, Tiam1 and GEF-H1. In confluent epithelial monolayers, paracingulin depletion leads to increased RhoA activity and increased expression of mRNA for the tight junction protein claudin-2. During tight junction assembly by the calcium-switch, Rac1 shows two transient peaks of activity, at earlier (10–20 min) and later (3–8 h) time points. Paracingulin depletion reduces such peaks of Rac1 activation in a Tiam1-dependent manner, resulting in a delay in junction formation. Paracingulin physically interacts with GEF-H1 and Tiam1 in vivo and in vitro, and it is required for their efficient recruitment to junctions, based on immunofluorescence and biochemical experiments. Our results provide the first description of a junctional protein that interacts with GEFs for both Rac1 and RhoA, and identify a novel molecular mechanism whereby Rac1 is activated during junction formation.

scholarly journals Eap1p, an Adhesin That Mediates Candida albicans Biofilm Formation In Vitro and In Vivo

2007 ◽  
Vol 6 (6) ◽  
pp. 931-939 ◽  
Author(s):  
Fang Li ◽  
Michael J. Svarovsky ◽  
Amy J. Karlsson ◽  
Joel P. Wagner ◽  
Karen Marchillo ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Cell Adhesion ◽  
Biofilm Formation ◽  
Fungal Infections ◽  
Gene Dosage ◽  
Venous Catheter ◽  
Flow Chamber ◽  
Dependent Manner

ABSTRACT Candida albicans is the leading cause of systemic fungal infections in immunocompromised humans. The ability to form biofilms on surfaces in the host or on implanted medical devices enhances C. albicans virulence, leading to antimicrobial resistance and providing a reservoir for infection. Biofilm formation is a complex multicellular process consisting of cell adhesion, cell growth, morphogenic switching between yeast form and filamentous states, and quorum sensing. Here we describe the role of the C. albicans EAP1 gene, which encodes a glycosylphosphatidylinositol-anchored, glucan-cross-linked cell wall protein, in adhesion and biofilm formation in vitro and in vivo. Deleting EAP1 reduced cell adhesion to polystyrene and epithelial cells in a gene dosage-dependent manner. Furthermore, EAP1 expression was required for C. albicans biofilm formation in an in vitro parallel plate flow chamber model and in an in vivo rat central venous catheter model. EAP1 expression was upregulated in biofilm-associated cells in vitro and in vivo. Our results illustrate an association between Eap1p-mediated adhesion and biofilm formation in vitro and in vivo.

scholarly journals Tenovin-6 impairs autophagy by inhibiting autophagic flux

2017 ◽  
Vol 8 (2) ◽  
pp. e2608-e2608 ◽  
Author(s):  
Hongfeng Yuan ◽  
Brandon Tan ◽  
Shou-Jiang Gao
Keyword(s):  
Cell Types ◽  
Inhibitory Effect ◽  
Lymphocytic Leukemia ◽  
Autophagic Flux ◽  
Dependent Manner ◽  
Autophagy Pathway ◽  
Sarcoma Cells ◽  
Regulatory Functions

Abstract Tenovin-6 has attracted significant interest because it activates p53 and inhibits sirtuins. It has anti-neoplastic effects on multiple hematopoietic malignancies and solid tumors in both in vitro and in vivo studies. Tenovin-6 was recently shown to impair the autophagy pathway in chronic lymphocytic leukemia cells and pediatric soft tissue sarcoma cells. However, whether tenovin-6 has a general inhibitory effect on autophagy and whether there is any involvement with SIRT1 and p53, both of which are regulators of the autophagy pathway, remain unclear. In this study, we have demonstrated that tenovin-6 increases microtubule-associated protein 1 light chain 3 (LC3-II) level in diverse cell types in a time- and dose-dependent manner. Mechanistically, the increase of LC3-II by tenovin-6 is caused by inhibition of the classical autophagy pathway via impairing lysosomal function without affecting the fusion between autophagosomes and lysosomes. Furthermore, we have revealed that tenovin-6 activation of p53 is cell type dependent, and tenovin-6 inhibition of autophagy is not dependent on its regulatory functions on p53 and SIRT1. Our results have shown that tenovin-6 is a potent autophagy inhibitor, and raised the precaution in interpreting results where tenovin-6 is used as an inhibitor of SIRT1.

scholarly journals Mitochondrial Calcium Uptake Capacity Modulates Neocortical Excitability

2013 ◽  
Vol 33 (7) ◽  
pp. 1115-1126 ◽  
Author(s):  
Basavaraju G Sanganahalli ◽  
Peter Herman ◽  
Fahmeed Hyder ◽  
Sridhar S Kannurpatti
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Cell Types ◽  
Dependent Manner ◽  
Evoked Responses ◽  
Blood Oxygen Level ◽  
Calcium Uniporter ◽  
Sensory Evoked

Local calcium (Ca2 +) changes regulate central nervous system metabolism and communication integrated by subcellular processes including mitochondrial Ca2 + uptake. Mitochondria take up Ca2 + through the calcium uniporter (mCU) aided by cytoplasmic microdomains of high Ca2 +. Known only in vitro, the in vivo impact of mCU activity may reveal Ca2 + -mediated roles of mitochondria in brain signaling and metabolism. From in vitro studies of mitochondrial Ca2 + sequestration and cycling in various cell types of the central nervous system, we evaluated ranges of spontaneous and activity-induced Ca2 + distributions in multiple subcellular compartments in vivo. We hypothesized that inhibiting (or enhancing) mCU activity would attenuate (or augment) cortical neuronal activity as well as activity-induced hemodynamic responses in an overall cytoplasmic and mitochondrial Ca2 + -dependent manner. Spontaneous and sensory-evoked cortical activities were measured by extracellular electrophysiology complemented with dynamic mapping of blood oxygen level dependence and cerebral blood flow. Calcium uniporter activity was inhibited and enhanced pharmacologically, and its impact on the multimodal measures were analyzed in an integrated manner. Ru360, an mCU inhibitor, reduced all stimulus-evoked responses, whereas Kaempferol, an mCU enhancer, augmented all evoked responses. Collectively, the results confirm aforementioned hypotheses and support the Ca2 + uptake-mediated integrative role of in vivo mitochondria on neocortical activity.

SM22α inhibits lamellipodium formation and migration via Ras-Arp2/3 signaling in synthetic VSMCs

2016 ◽  
Vol 311 (5) ◽  
pp. C758-C767 ◽  
Author(s):  
Pin Lv ◽  
Fan Zhang ◽  
Ya-Juan Yin ◽  
Yu-Can Wang ◽  
Min Gao ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Vascular Lesion ◽  
Flavonoid Compound ◽  
Cell Cortex ◽  
Dependent Manner ◽  
Nucleotide Exchange ◽  
Migration Activity ◽  
And Migration

We previously demonstrated that smooth muscle (SM) 22α promotes the migration activity in contractile vascular smooth muscle cells (VSMCs). Based on the varied functions exhibited by SM22α in different VSMC phenotypes, we investigated the effect of SM22α on VSMC migration under pathological conditions. The results demonstrated that SM22α overexpression in synthetic VSMCs inhibited platelet-derived growth factor (PDGF)-BB-induced cell lamellipodium formation and migration, which was different from its action in contractile cells. The results indicated two distinct mechanisms underlying inhibition of lamellipodium formation by SM22α, increased actin dynamic stability and decreased Ras activity via interference with interactions between Ras and guanine nucleotide exchange factor. The former inhibited actin cytoskeleton rearrangement in the cell cortex, while the latter significantly disrupted actin nucleation activation of the Arp2/3 complex. Baicalin, a herb-derived flavonoid compound, inhibited VSMC migration via upregulation of SM22α expression in vitro and in vivo. These data suggest that SM22α regulates lamellipodium formation and cell migration in a phenotype-dependent manner in VSMCs, which may be a new therapeutic target for vascular lesion formation.

scholarly journals A mechanism of Rap1-induced stabilization of endothelial cell–cell junctions

2011 ◽  
Vol 22 (14) ◽  
pp. 2509-2519 ◽  
Author(s):  
Jian J. Liu ◽  
Rebecca A. Stockton ◽  
Alexandre R. Gingras ◽  
Ararat J. Ablooglu ◽  
Jaewon Han ◽  
...  
Keyword(s):  
Endothelial Cell ◽  
Small Gtpases ◽  
Cell Junctions ◽  
Physical Interaction ◽  
Dependent Manner ◽  
Cardiovascular Development ◽  
Cavernous Malformations ◽  
Cell Cell

Activation of Rap1 small GTPases stabilizes cell–cell junctions, and this activity requires Krev Interaction Trapped gene 1 (KRIT1). Loss of KRIT1 disrupts cardiovascular development and causes autosomal dominant familial cerebral cavernous malformations. Here we report that native KRIT1 protein binds the effector loop of Rap1A but not H-Ras in a GTP-dependent manner, establishing that it is an authentic Rap1-specific effector. By modeling the KRIT1–Rap1 interface we designed a well-folded KRIT1 mutant that exhibited a ∼40-fold-reduced affinity for Rap1A and maintained other KRIT1-binding functions. Direct binding of KRIT1 to Rap1 stabilized endothelial cell–cell junctions in vitro and was required for cardiovascular development in vivo. Mechanistically, Rap1 binding released KRIT1 from microtubules, enabling it to locate to cell–cell junctions, where it suppressed Rho kinase signaling and stabilized the junctions. These studies establish that the direct physical interaction of Rap1 with KRIT1 enables the translocation of microtubule-sequestered KRIT1 to junctions, thereby supporting junctional integrity and cardiovascular development.

scholarly journals Scribble, Lgl1, and myosin II form a complex in vivo to promote directed cell migration

2020 ◽  
Vol 31 (20) ◽  
pp. 2234-2248
Author(s):  
Maha Abedrabbo ◽  
Shoshana Ravid
Keyword(s):  
Cell Migration ◽  
Cell Adhesion ◽  
Myosin Ii ◽  
Leading Edge ◽  
Directed Cell Migration ◽  
Lethal Giant Larvae ◽  
And Migration ◽  
Migrating Cells

Here we show that Scribble (Scrib), Lethal giant larvae 1 (Lgl1), and myosin II form a complex in vivo and colocalize at the cell leading edge of migrating cells, and this colocalization is interdependent. Scrib and Lgl1 are required for proper cell adhesion, polarity, and migration.

scholarly journals Inhibition of Orbivirus Replication by Aurintricarboxylic Acid

2020 ◽  
Vol 21 (19) ◽  
pp. 7294
Author(s):  
Celia Alonso ◽  
Sergio Utrilla-Trigo ◽  
Eva Calvo-Pinilla ◽  
Luis Jiménez-Cabello ◽  
Javier Ortego ◽  
...  
Keyword(s):  
Cell Types ◽  
Dependent Manner ◽  
Biting Midges ◽  
Lethal Challenge ◽  
Concentration Dependent Manner ◽  
Antiviral Compound ◽  
Aurintricarboxylic Acid ◽  
And Control

Bluetongue virus (BTV) and African horse sickness virus (AHSV) are vector-borne viruses belonging to the Orbivirus genus, which are transmitted between hosts primarily by biting midges of the genus Culicoides. With recent BTV and AHSV outbreaks causing epidemics and important economy losses, there is a pressing need for efficacious drugs to treat and control the spread of these infections. The polyanionic aromatic compound aurintricarboxylic acid (ATA) has been shown to have a broad-spectrum antiviral activity. Here, we evaluated ATA as a potential antiviral compound against Orbivirus infections in both mammalian and insect cells. Notably, ATA was able to prevent the replication of BTV and AHSV in both cell types in a time- and concentration-dependent manner. In addition, we evaluated the effect of ATA in vivo using a mouse model of infection. ATA did not protect mice against a lethal challenge with BTV or AHSV, most probably due to the in vivo effect of ATA on immune system regulation. Overall, these results demonstrate that ATA has inhibitory activity against Orbivirus replication in vitro, but further in vivo analysis will be required before considering it as a potential therapy for future clinical evaluation.

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