Proximity proteomics provides a new resource for exploring the function of Afadin and the complexity of cell-cell adherens junctions.

The network of proteins at the interface between cell-cell adherens junctions and the actomyosin cytoskeleton provides robust yet dynamic connections that facilitate cell shape change and motility. While this was initially thought to be a simple linear connection via classic cadherins and their associated catenins, we now have come to appreciate that many more proteins are involved, providing robustness and mechanosensitivity. Defining the full network of proteins in this network remains a key objective in our field.

Scribble and Discs-large direct initial assembly and positioning of adherens junctions during the establishment of apical-basal polarity.

Apical-basal polarity is a fundamental property of animal tissues. embryos provide an outstanding model for defining mechanisms that initiate and maintain polarity. Polarity is initiated during cellularization, when cell-cell adherens junctions are positioned at the future boundary of apical and basolateral domains.

Intracellular MLCK1 diversion reverses barrier loss to restore mucosal homeostasis.

Epithelial barrier loss is a driver of intestinal and systemic diseases. Myosin light chain kinase (MLCK) is a key effector of barrier dysfunction and a potential therapeutic target, but enzymatic inhibition has unacceptable toxicity. Here, we show that a unique domain within the MLCK splice variant MLCK1 directs perijunctional actomyosin ring (PAMR) recruitment.

The scaffolding protein ZO-1 coordinates actomyosin and epithelial apical specializations and .

Polarized epithelia assemble into sheets that compartmentalize organs and generate tissue barriers by integrating apical surfaces into a single, unified structure. This tissue organization is shared across organs, species, and developmental stages. The processes that regulate development and maintenance of apical epithelial surfaces are, however, undefined.

Contributions of intestinal epithelial barriers to health and disease.

A core function of epithelia is to form barriers that separate tissue compartments within complex organisms. These barriers also separate the internal milieu from the external environment and are, therefore, an essential component of host defense. However, in many cases, a perfect barrier would be improbable with life itself.

Remodeling the zonula adherens in response to tension and the role of afadin in this response.

Morphogenesis requires dynamic coordination between cell-cell adhesion and the cytoskeleton to allow cells to change shape and move without losing tissue integrity. We used genetic tools and superresolution microscopy in a simple model epithelial cell line to define how the molecular architecture of cell-cell zonula adherens (ZA) is modified in response to elevated contractility, and how these cells maintain tissue integrity. We previously found that depleting zonula occludens 1 (ZO-1) family proteins in MDCK cells induces a highly organized contractile actomyosin array at the ZA.

Rap1 and Canoe/afadin are essential for establishment of apical-basal polarity in the Drosophila embryo.

The establishment and maintenance of apical-basal cell polarity is critical for assembling epithelia and maintaining organ architecture. Drosophila embryos provide a superb model. In the current view, apically positioned Bazooka/Par3 is the initial polarity cue as cells form during cellularization.

A contractile actomyosin network linked to adherens junctions by Canoe/afadin helps drive convergent extension.

Integrating individual cell movements to create tissue-level shape change is essential to building an animal. We explored mechanisms of adherens junction (AJ):cytoskeleton linkage and roles of the linkage regulator Canoe/afadin during Drosophila germband extension (GBE), a convergent-extension process elongating the body axis. We found surprising parallels between GBE and a quite different morphogenetic movement, mesoderm apical constriction.

The single Drosophila ZO-1 protein Polychaetoid regulates embryonic morphogenesis in coordination with Canoe/afadin and Enabled.

Adherens and tight junctions play key roles in assembling epithelia and maintaining barriers. In cell culture zonula occludens (ZO)-family proteins are important for assembly/maturation of both tight and adherens junctions (AJs). Genetic studies suggest that ZO proteins are important during normal development, but interpretation of mouse and fly studies is limited by genetic redundancy and/or a lack of null alleles.

Protein expression in platelets from six species that differ in their open canalicular system.

Platelets contain an invaginated, tubular membranous structure called the surface-connected open canalicular system (SCCS or OCS), which is contiguous with the plasma membrane and serves as a site for granule fusion and as a reservoir of membrane for platelet spreading. According to ultrastructural studies, platelets from some species lack OCS. In an attempt to correlate biochemical and functional attributes with the presence of an OCS, platelets from human, mouse and dog (OCS(+)), and from cow, camel and horse (OCS(-)) were analysed for differential protein expression and aggregation in response to thrombin.

Primary platelet signaling cascades and integrin-mediated signaling control ADP-ribosylation factor (Arf) 6-GTP levels during platelet activation and aggregation.

Previous studies showed that ADP-ribosylation factor 6 (Arf6) is important for platelet function; however, little is known about which signaling events regulate this small GTP-binding protein. Arf6-GTP was monitored in platelets stimulated with a number of agonists (TRAP, thrombin, convulxin, collagen, PMA, thapsigargin, or A23187) and all led to a time-dependent decrease in Arf6-GTP. ADP and U46619 were without effect.

Endobrevin/VAMP-8 is the primary v-SNARE for the platelet release reaction.

Platelet secretion is critical to hemostasis. Release of granular cargo is mediated by soluble NSF attachment protein receptors (SNAREs), but despite consensus on t-SNAREs usage, it is unclear which Vesicle Associated Membrane Protein (VAMPs: synaptobrevin/VAMP-2, cellubrevin/VAMP-3, TI-VAMP/VAMP-7, and endobrevin/VAMP-8) is required. We demonstrate that VAMP-8 is required for release from dense core granules, alpha granules, and lysosomes.

Arf6 plays an early role in platelet activation by collagen and convulxin.

Small GTPases play critical roles in hemostasis, though the roster of such molecules in platelets is not complete. In this study, we report the presence of Ras-related GTPases of the ADP-ribosylation factor (Arf) family. Platelets contain Arf1 or 3 and Arf6, with the latter being predominantly membrane associated.

Platelets from Munc18c heterozygous mice exhibit normal stimulus-induced release.

A critical aspect of hemostasis is the release of clot-forming components from the three intra-platelet stores: dense core granules, alpha-granules and lysosomes. Exocytosis from these granules is mediated by soluble (SNAPs and NSF) and integralmembrane proteins (v- and t-SNAREs). Three SM (Sec1/Munc18) proteins are present in mouse platelets (Munc18a, 18b and 18c) and each potentially regulates exocytosis via modulation of their cognate syntaxin binding partner.

PCB 104-induced proinflammatory reactions in human vascular endothelial cells: relationship to cancer metastasis and atherogenesis.

Polychlorinated biphenyls (PCBs) are widespread environmental contaminants that are known to induce carcinogenic and possibly atherogenic events. Recent evidence suggests that selected PCBs may be potent developmental agents of vascular inflammatory responses by inducing cellular oxidative stress and activating redox-responsive transcription factors. Therefore, the aim of this paper is to investigate PCB-induced proinflammatory reactions in human vascular endothelial cells.