Von Willebrand Factor multimerization and the polarity of secretory pathways in endothelial cells

The Von Willebrand factor (VWF) synthesised and secreted by endothelial cells is central to haemostasis and thrombosis, providing a multifunctional adhesive platform that brings together components needed for these processes. VWF secretion can occur from both apical and basolateral sides of endothelial cells, and from constitutive, basal and regulated secretory pathways, the latter two via Weibel-Palade bodies (WPB). Although the amount and structure of VWF is crucial to its function, the extent of VWF release, multimerization and polarity of the three secretory pathways have only been addressed separately and with conflicting results. We set out to clarify these relationships using polarized Human Umbilical Vein Endothelial Cells (HUVECs) grown on Transwell membranes. We found that regulated secretion of Ultra large (UL) molecular weight VWF predominantly occurred apically, consistent with a role in localised platelet capture in the vessel lumen. We found that constitutive secretion of low molecular weight (LMW) VWF is targeted basolaterally, toward the subendothelial matrix, using the adaptor protein complex 1 (AP-1), where it may provide the bulk of collagen bound subendothelial VWF. We also found that basally-secreted VWF is composed of UL-VWF, released continuously from WPBs in the absence of stimuli, and occurs predominantly apically, suggesting this could be the main source of circulating plasma VWF. Together, we provide a unified dataset reporting the amount and multimeric state of VWF secreted from the constitutive, basal and regulated pathways in polarized HUVECs, and have established a new role for AP-1 in the basolateral constitutive secretion of VWF

Valorização do trabalho humano: uma diretriz constitucional esquecida em meio à crise econômica e às consequentes propostas flexibilizantes

RESUMO: A flexibilização dos direitos trabalhistas é assunto em evidência na realidade econômica de nosso país, mormente em meio ao cenário de crise econômica que vivenciamos. O objetivo deste trabalho é refletir sobre a compatibilidade entre o raciocínio econômico, que entoa as atuais propostas de relativização da legislação trabalhista, e as balizas jurídicas conformadoras da Ordem Econômica constitucional, em especial o valor social do trabalho humano.  Por meio de pesquisa bibliográfica e análise normativa constitucional e infraconstitucional, será realizada, primeiramente, uma digressão sobre a evolução do ordenamento jurídico protetivo trabalhista e das propostas flexibilizantes que o acompanham na história.  Uma vez observado o histórico atrito entre os interesses empresariais e a proteção social trabalhista, o trabalho se ocupará em aprofundar as principais características que notabilizam esse antagonismo entre racionalidades econômica e laboral-protetiva. A partir daí, aclaradas as premissas atinentes aos diferentes pontos de vista que envolvem o tema e partindo para a apreciação em um plano constitucional mais abstrato, axiológico, o texto seguirá no sentido de perquirir, à luz de uma leitura moral (dworkiniana) do problema constitucional, o modo como o ponto de vista patrimonialista típico das categorias econômicas deverá se compatibilizar com a realização dos fins sociais atinentes à valorização do trabalho humano.  Ao final, proporemos que, no atual contexto democrático de direito, os interesses empresariais de flexibilização da tutela trabalhista, apesar de atuarem legitimamente mediante uma racionalidade econômica no sentido de minimizar custos e maximizar riquezas, devem ser limitados pelas diretrizes constitucionais que, a partir de um robusto aparato normativo de proteção da pessoa humana, evidenciam a predileção pela tutela do trabalhador frente aos interesses mercantis, sob pena de nos distanciarmos a passos largos do ideal de justiça e equidade.PALAVRAS-CHAVE: Direito Constitucional do Trabalho. Flexibilização. Racionalidade econômica. Valor social do trabalho. ABSTRACT: The flexibilization of labor rights is an issue in the economic reality of our country, especially in the context of the economic crisis we are experiencing. The objective of this work is to reflect on the compatibility between the economic reasoning, linked with the current proposals for relativization of labor legislation, and the legal frameworks from Constitutional Economic Order, especially the social value of human labor. Through a bibliographical research and constitutional and infraconstitutional normative analysis, a digression will be made first on the evolution of the labor protection legal system and the flexibilizing proposals in history. Once the historical friction between corporate interests and labor social protection is observed, this work will focus on deepening the main characteristics that distinguish this antagonism between economic and labor-protection rationalities. Clarifying the premises concerning the different points of view that involve the theme and starting for the appreciation in a more abstract, axiological constitutional plan, the text will follow in order to investigate how the patrimonialist viewpoint of the economic categories should be compatible with the social purposes related to the valorization of human work, based on a moral (Dworkinian) interpretation of the constitutional problem. In the end, we will propose that, in the current democratic context of law, the business interests in flexibilization of labor protection, although acting legitimately through economic rationality to minimize costs and maximize wealth, should be limited by the constitutional guidelines that, from a robust normative apparatus of human protection, evidences the predilection for the protection of the worker against the mercantile interests, otherwise we would distance ourselves from the ideal of justice and equity.KEYWORDS: Constitutional Labor Law. Flexibilization. Economic rationality. Social value of labor. Submetido em: 31-03-2017Aprovado em: 14-07-201

Propriétés psychométriques de l’échelle de satisfaction des cours académiques (ESCA) chez les étudiants universitaires brésiliens

Academic satisfaction has been studied from different perspectives that considerate distinct ways of measurement. However, the plurality of evaluated facets prevents a more parsimonious assessment of the general students’ academic satisfaction. In the article, we aimed to provide psychometric evidence of the validity and reliability for the AMSS in Brazil in two studies (N = 893). In Study 1, an exploratory factor analysis and item parameters (Item Response Theory) support the one-factor solution and the suitability of the six items. Moreover, evidence for factorial invariance across gender and convergent validity with the PANAS and with the SWLS was also presented in Study 2. In conclusion, the present paper provides evidence of the adequacy of the AMSS to evaluate global satisfaction with the academics course in Brazil.Propiedades psicométricas de la Escala de Satisfacción del Curso Académico (ESCA) en estudiantes universitarios brasileños La satisfacción académica ha sido estudiada bajo diferentes perspectivas, produciendo dife- rentes formas de medición. Sin embargo, la pluralidad de facetas evaluadas impide una evaluación más parsimoniosa de la satisfacción académica de los estudiantes en general. En este artículo, objetivamos proporcionar evidencias psicométricas de la validez y con- fiabilidad para el ESCA en Brasil en dos estudios (N = 893). En el Estudio 1, un análisis factorial exploratorio y los parámetros de los ítems (Teoría de Respuesta al Item) soportan la solución unifatorial y la adecuación de los seis ítems. Además, se presentaron evidencias de invariancia factorial entre género y validez convergente con el PANAS y con el ESV en el Estudio 2. En conclusión, este estudio proporciona evidencias de la adecuación de la ESCA para evaluar la satisfacción global con el curso académico en Brasil.A satisfação acadêmica tem sido estudada sob diferentes perspectivas que contemplam formas distintas de mensuração. Entretanto, a pluralidade de facetas avaliadas impede uma avaliação mais parcimoniosa da satisfação acadêmica dos estudantes em geral. O presente estudo tem por objetivo fornecer evidências psicométricas da validade e confiabilidade para o ESCA no Brasil em dois estudos (N = 893). No Estudo 1, uma análise fatorial exploratória e os parâmetros dos itens (Teoria de Resposta ao Item) suportam a solução unifatorial e a adequação dos seis itens. Além disso, foram apresentadas evidências de invariância fatorial entre gênero e validade convergente com o PANAS e com o ESV no Estudo 2. Em con- clusão, este estudo fornece evidências da adequação da ESCA para avaliar a satisfação global com o curso acadêmico na versão em português.La satisfaction académique a été étudiée sous différentes perspectives qui envisagent différentes formes de mesure. Cependant, la pluralité des facettes évaluées empêche une évaluation plus parcimonieuse de la satisfaction académique des étudiants en général. La pré- sente étude vise à fournir des preuves psychométriques de validité et de fiabilité pour ESCA au Brésil dans deux études (N = 893). Dans l’étude 1, une analyse factorielle exploratoire et les paramètres d’item (Théorie de la réponse à l’item) corroborent la solution à un facteur et l’adéquation des six items. En outre, nous avons présenté des preuves d’invariance factorielle entre le sexe et la validité convergentes avec PANAS et ESV dans l’étude 2. En conclusion, cette étude fournit des preuves de l’aptitude de l’ESCA à évaluer la satisfaction générale à l’égard du cours universitaire dans la version portugaise

Weibel-Palade bodies at a glance

The vascular environment can rapidly alter, and the speed with which responses to both physiological and pathological changes are required necessitates the existence of a highly responsive system. The endothelium can quickly deliver bioactive molecules by regulated exocytosis of its secretory granules, the Weibel−Palade bodies (WPBs). WPBs include proteins that initiate both haemostasis and inflammation, as well those that modulate blood pressure and angiogenesis. WPB formation is driven by von Willebrand factor, their most abundant protein, which controls both shape and size of WPBs. WPB are generated in a range of sizes, with the largest granules over ten times the size of the smallest. In this Cell Science at a Glance and the accompanying poster, we discuss the emerging mechanisms by which WPB size is controlled and how this affects the ability of this organelle to modulate haemostasis. We will also outline the different modes of exocytosis and their polarity that are currently being explored, and illustrate that these large secretory organelles provide a model for how elements of secretory granule biogenesis and exocytosis cooperate to support a complex and diverse set of functions

Dark spinor models in gravitation and cosmology

We introduce and carefully define an entire class of field theories based on non-standard spinors. Their dominant interaction is via the gravitational field which makes them naturally dark; we refer to them as Dark Spinors. We provide a critical analysis of previous proposals for dark spinors noting that they violate Lorentz invariance. As a working assumption we restrict our analysis to non-standard spinors which preserve Lorentz invariance, whilst being non-local and explicitly construct such a theory. We construct the complete energy-momentum tensor and derive its components explicitly by assuming a specific projection operator. It is natural to next consider dark spinors in a cosmological setting. We find various interesting solutions where the spinor field leads to slow roll and fast roll de Sitter solutions. We also analyse models where the spinor is coupled conformally to gravity, and consider the perturbations and stability of the spinor.Comment: 43 pages. Several new sections and details added. JHEP in prin

A GBF1-Dependent Mechanism for Environmentally Responsive Regulation of ER-Golgi Transport

How can anterograde membrane trafficking be modulated by physiological cues? A screen of Golgi-associated proteins revealed that the ARF-GEF GBF1 can selectively modulate the ER-Golgi trafficking of prohaemostatic von Willebrand factor (VWF) and extracellular matrix (ECM) proteins in human endothelial cells and in mouse fibroblasts. The relationship between levels of GBF1 and the trafficking of VWF into forming secretory granules confirmed GBF1 is a limiting factor in this process. Further, GBF1 activation by AMPK couples its control of anterograde trafficking to physiological cues; levels of glucose control GBF1 activation in turn modulating VWF trafficking into secretory granules. GBF1 modulates both ER and TGN exit, the latter dramatically affecting the size of the VWF storage organelles, thereby influencing the hemostatic capacity of the endothelium. The role of AMPK as a central integrating element of cellular pathways with intra- and extra-cellular cues can now be extended to modulation of the anterograde secretory pathway

Tuning the endothelial response: differential release of exocytic cargos from Weibel-Palade bodies.

Essentials Endothelial activation initiates multiple processes, including hemostasis and inflammation. The molecules that contribute to these processes are co-stored in secretory granules. How can the cells control release of granule content to allow differentiated responses? Selected agonists recruit an exocytosis-linked actin ring to boost release of a subset of cargo. SUMMARY: Background Endothelial cells harbor specialized storage organelles, Weibel-Palade bodies (WPBs). Exocytosis of WPB content into the vascular lumen initiates primary hemostasis, mediated by von Willebrand factor (VWF), and inflammation, mediated by several proteins including P-selectin. During full fusion, secretion of this large hemostatic protein and smaller pro-inflammatory proteins are thought to be inextricably linked. Objective To determine if secretagogue-dependent differential release of WPB cargo occurs, and whether this is mediated by the formation of an actomyosin ring during exocytosis. Methods We used VWF string analysis, leukocyte rolling assays, ELISA, spinning disk confocal microscopy, high-throughput confocal microscopy and inhibitor and siRNA treatments to demonstrate the existence of cellular machinery that allows differential release of WPB cargo proteins. Results Inhibition of the actomyosin ring differentially effects two processes regulated by WPB exocytosis; it perturbs VWF string formation but has no effect on leukocyte rolling. The efficiency of ring recruitment correlates with VWF release; the ratio of release of VWF to small cargoes decreases when ring recruitment is inhibited. The recruitment of the actin ring is time dependent (fusion events occurring directly after stimulation are less likely to initiate hemostasis than later events) and is activated by protein kinase C (PKC) isoforms. Conclusions Secretagogues differentially recruit the actomyosin ring, thus demonstrating one mechanism by which the prothrombotic effect of endothelial activation can be modulated. This potentially limits thrombosis whilst permitting a normal inflammatory response. These results have implications for the assessment of WPB fusion, cargo-content release and the treatment of patients with von Willebrand disease.British Heart Foundation. Grant Number: PG/15/72/31732. Medical Research Council. Grant Numbers: MC_UU_12018/2, MR/M019179/1

Left-handed color-sextet diquark in Kaon system

We investigate whether a color-sextet scalar diquark (${\bf H}_6$) coupling to the left-handed quarks contributes to the $\Delta S=2$ process. It is found that the box diagrams mediated by $W$ and ${\bf H}_6$ bosons have no contributions to $\Delta S=2$ when the limit of $m_t=0$ is used, and the flavor mixing matrices for diagonalizing quark mass matrices are introduced at the same time. When the heavy top-quark mass effects are taken into account, it is found that in addition to the $W-{\bf H}_6$ box diagrams significantly contributing to $\Delta S=2$, their effects can be as large as those from the ${\bf H}_6-{\bf H}_6$ box diagrams. Using the parameters that are constrained by the $K^0-\bar K^0$ mixing parameter $\Delta M_K$ and the Kaon indirect CP violation $\epsilon_K$, we find that the left-handed color-sextet diquark can lead to the Kaon direct CP violation being $Re(\epsilon'/\epsilon) \sim 0.4 \times 10^{-3}$. In the chosen scheme, although the diquark contribution to $K_L\to \pi^0 \nu \bar\nu$ is small, the branching ratio of $K^+ \to \pi^+ \nu \bar\nu$ can reach the current experimental upper bound.Comment: 22 pages, 6 figure