ZO-1 Regulates Hippo-Independent YAP Activity and Cell Proliferation via a GEF-H1- and TBK1-Regulated Signalling Network.

Tight junctions are a barrier-forming cell-cell adhesion complex and have been proposed to regulate cell proliferation. However, the underlying mechanisms are not well understood. Here, we used cells deficient in the junction scaffold ZO-1 alone or together with its paralog ZO-2, which disrupts the junctional barrier.

Tight junctions.

Various functions within our bodies require the generation and maintenance of compartments with distinct compositions, which in turn necessitate the formation of semipermeable cellular diffusion barriers. For example, the blood-brain barrier protects the brain by allowing only specific molecules to pass through. Another instance is the intestinal barrier, which allows the uptake of essential nutrients, while restricting the passage of pathogenic molecules and bacteria.

Bottom-Up Synthesis of De-Functionalized and Dispersible Carbon Spheres as Colloidal Adsorbent.

Recent innovative adsorption technologies for water purification rely on micrometer-sized activated carbon (AC) for ultrafast adsorption or in situ remediation. In this study, the bottom-up synthesis of tailored activated carbon spheres (aCS) from sucrose as renewable feedstock is demonstrated. The synthesis is based on a hydrothermal carbonization step followed by a targeted thermal activation of the raw material.

ZO-1 Guides Tight Junction Assembly and Epithelial Morphogenesis via Cytoskeletal Tension-Dependent and -Independent Functions.

Formation and maintenance of tissue barriers require the coordination of cell mechanics and cell-cell junction assembly. Here, we combined methods to modulate ECM stiffness and to measure mechanical forces on adhesion complexes to investigate how tight junctions regulate cell mechanics and epithelial morphogenesis. We found that depletion of the tight junction adaptor ZO-1 disrupted junction assembly and morphogenesis in an ECM stiffness-dependent manner and led to a stiffness-dependant reorganisation of active myosin.

Spatiotemporal control of actomyosin contractility by MRCKβ signaling drives phagocytosis.

Phagocytosis requires actin dynamics, but whether actomyosin contractility plays a role in this morphodynamic process is unclear. Here, we show that in the retinal pigment epithelium (RPE), particle binding to Mer Tyrosine Kinase (MerTK), a widely expressed phagocytic receptor, stimulates phosphorylation of the Cdc42 GEF Dbl3, triggering activation of MRCKβ/myosin-II and its coeffector N-WASP, membrane deformation, and cup formation. Continued MRCKβ/myosin-II activity then drives recruitment of a mechanosensing bridge, enabling cytoskeletal force transmission, cup closure, and particle internalization.

Uniform and dispersible carbonaceous microspheres as quasi-liquid sorbent.

Functional colloidal carbon materials find various applications, including the remediation of contaminated water and soil in so-called particle-based in-situ remediation processes. In this study, uniform and highly dispersible micro-sized carbonaceous spheres (CS) were generated by hydrothermal carbonization (HTC) of sucrose in the presence of carboxymethyl cellulose (CMC) as environmentally friendly polyelectrolyte stabilizer. In order to ensure their optimal subsurface delivery and formation of a self-contained treatment zone, a narrow size distribution and low agglomeration tendency of the particles is desired.

Therapeutic Validation of GEF-H1 Using a De Novo Designed Inhibitor in Models of Retinal Disease.

Inflammation and fibrosis are important components of diseases that contribute to the malfunction of epithelia and endothelia. The Rho guanine nucleotide exchange factor (GEF) GEF-H1/ARHGEF-2 is induced in disease and stimulates inflammatory and fibrotic processes, cell migration, and metastasis. Here, we have generated peptide inhibitors to block the function of GEF-H1.

Spatio-temporal expression pattern and role of the tight junction protein MarvelD3 in pancreas development and function.

Tight junction complexes are involved in the establishment and maintenance of cell polarity and the regulation of signalling pathways, controlling biological processes such as cell differentiation and cell proliferation. MarvelD3 is a tight junction protein expressed in adult epithelial and endothelial cells. In Xenopus laevis, MarvelD3 morphants present differentiation defects of several ectodermal derivatives.

ARHGEF18/p114RhoGEF Coordinates PKA/CREB Signaling and Actomyosin Remodeling to Promote Trophoblast Cell-Cell Fusion During Placenta Morphogenesis.

Coordination of cell-cell adhesion, actomyosin dynamics and gene expression is crucial for morphogenetic processes underlying tissue and organ development. Rho GTPases are main regulators of the cytoskeleton and adhesion. They are activated by guanine nucleotide exchange factors in a spatially and temporally controlled manner.

Proper E-cadherin membrane location in colon requires Dab2 and it modifies by inflammation and cancer.

We reported that Disabled-2 (Dab2) is located at the apical membrane in suckling rat intestine. Here, we discovered that, in colon of suckling and adult mouse and of adult human, Dab2 is only at lateral crypt cell membrane and colocalized with E-cadherin. Dab2 depletion in Caco-2 cells led to E-cadherin internalization indicating that its membrane location requires Dab2.

Mechanosensation of Tight Junctions Depends on ZO-1 Phase Separation and Flow.

Cell-cell junctions respond to mechanical forces by changing their organization and function. To gain insight into the mechanochemical basis underlying junction mechanosensitivity, we analyzed tight junction (TJ) formation between the enveloping cell layer (EVL) and the yolk syncytial layer (YSL) in the gastrulating zebrafish embryo. We found that the accumulation of Zonula Occludens-1 (ZO-1) at TJs closely scales with tension of the adjacent actomyosin network, revealing that these junctions are mechanosensitive.

Small and large intestine express a truncated Dab1 isoform that assembles in cell-cell junctions and co-localizes with proteins involved in endocytosis.

Disabled-1 (Dab1) is an essential intracellular adaptor protein in the reelin pathway. Our previous studies in mice intestine showed that Dab1 transmits the reelin signal to cytosolic signalling pathways. Here, we determine the Dab1 isoform expressed in rodent small and large intestine, its subcellular location and co-localization with clathrin, caveolin-1 and N-Wasp.

Control of neural crest induction by MarvelD3-mediated attenuation of JNK signalling.

Tight junctions are required for the formation of tissue barriers and function as suppressors of signalling mechanisms that control gene expression and cell behaviour; however, little is known about the physiological and developmental importance of such signalling functions. Here, we demonstrate that depletion of MarvelD3, a transmembrane protein of tight junctions, disrupts neural crest formation and, consequently, development of neural crest-derived tissues during Xenopus embryogenesis. Using embryos and explant cultures combined with a small molecule inhibitor or mutant mRNAs, we show that MarvelD3 is required to attenuate JNK signalling during neural crest induction and that inhibition of JNK pathway activation is sufficient to rescue the phenotype induced by MarvelD3 depletion.

An apical MRCK-driven morphogenetic pathway controls epithelial polarity.

Polarized epithelia develop distinct cell surface domains, with the apical membrane acquiring characteristic morphological features such as microvilli. Cell polarization is driven by polarity determinants including the evolutionarily conserved partitioning-defective (PAR) proteins that are separated into distinct cortical domains. PAR protein segregation is thought to be a consequence of asymmetric actomyosin contractions.

Biallelic Mutation of ARHGEF18, Involved in the Determination of Epithelial Apicobasal Polarity, Causes Adult-Onset Retinal Degeneration.

Mutations in more than 250 genes are implicated in inherited retinal dystrophy; the encoded proteins are involved in a broad spectrum of pathways. The presence of unsolved families after highly parallel sequencing strategies suggests that further genes remain to be identified. Whole-exome and -genome sequencing studies employed here in large cohorts of affected individuals revealed biallelic mutations in ARHGEF18 in three such individuals.

Parkinsonian motor impairment predicts personality domains related to genetic risk and treatment outcomes in schizophrenia.

Identifying endophenotypes of schizophrenia is of critical importance and has profound implications on clinical practice. Here we propose an innovative approach to clarify the mechanims through which temperament and character deviance relates to risk for schizophrenia and predict long-term treatment outcomes. We recruited 61 antipsychotic naïve subjects with chronic schizophrenia, 99 unaffected relatives, and 68 healthy controls from rural communities in the Central Andes.

MarvelD3 regulates the c-Jun N-terminal kinase pathway during eye development in Xenopus.

Ocular morphogenesis requires several signalling pathways controlling the expression of transcription factors and cell-cycle regulators. However, despite a well-known mechanism, the dialogue between those signals and factors remains to be unveiled. Here, we identify a requirement for MarvelD3, a tight junction transmembrane protein, in eye morphogenesis in Xenopus MarvelD3 depletion led to an abnormally pigmented eye or even an eye-less phenotype, which was rescued by ectopic MarvelD3 expression.

Organ culture storage of pre-prepared corneal donor material for Descemet's membrane endothelial keratoplasty.

Purpose: To evaluate the effect of media composition and storage method on pre-prepared Descemet's membrane endothelial keratoplasty (DMEK) grafts.

Methods: 50 corneas were used. Endothelial wound healing and proliferation in different media were assessed using a standard injury model.

Tight junctions: from simple barriers to multifunctional molecular gates.

Epithelia and endothelia separate different tissue compartments and protect multicellular organisms from the outside world. This requires the formation of tight junctions, selective gates that control paracellular diffusion of ions and solutes. Tight junctions also form the border between the apical and basolateral plasma-membrane domains and are linked to the machinery that controls apicobasal polarization.

Tight junctions as regulators of tissue remodelling.

Formation of tissue barriers by epithelial and endothelial cells requires neighbouring cells to interact via intercellular junctions, which includes tight junctions. Tight junctions form a semipermeable paracellular diffusion barrier and act as signalling hubs that guide cell behaviour and differentiation. Components of tight junctions are also expressed in cell types not forming tight junctions, such as cardiomyocytes, where they associate with facia adherens and/or gap junctions.

Clozapine Rechallenge After Neutropenia or Leucopenia.

To rechallenge with clozapine for a patient who previously has experienced neutropenia or leucopenia or during clozapine treatment is a difficult clinical decision. Herein, we analyzed the results of such a rechallenge in 19 patients. We analyzed all the reports, from the database of the pharmacovigilance department of the Argentine National Administration of Drugs, Foods, and Medical Devices, of patients who were rechallenged with clozapine after a leucopenia or a neutropenia.

Global cell-by-cell evaluation of endothelial viability after two methods of graft preparation in Descemet membrane endothelial keratoplasty.

Purpose: To describe a novel method of global cell viability assessment for Descemet membrane endothelial keratoplasty (DMEK) and the comparison of two contemporary methods of donor tissue preparation.

Methods: DMEK transplants were prepared using two different methods: liquid bubble separation and manual peeling (n=8 each group). Samples were incubated with Hoechst, calcein-AM and ethidium homodimer prior to mounting on a curved imaging chamber.