Chemokine Transfer by Liver Sinusoidal Endothelial Cells Contributes to the Recruitment of CD4+ T Cells into the Murine Liver

Leukocyte adhesion and transmigration are central features governing immune surveillance and inflammatory reactions in body tissues. Within the liver sinusoids, chemokines initiate the first crucial step of T-cell migration into the hepatic tissue. We studied molecular mechanisms involved in endothelial chemokine supply during hepatic immune surveillance and liver inflammation and their impact on the recruitment of CD4+ T cells into the liver. In the murine model of Concanavalin A-induced T cell-mediated hepatitis, we showed that hepatic expression of the inflammatory CXC chemokine ligands (CXCL)9 and CXCL10 strongly increased whereas homeostatic CXCL12 significantly decreased. Consistently, CD4+ T cells expressing the CXC chemokine receptor (CXCR)3 accumulated within the inflamed liver tissue. In histology, CXCL9 was associated with liver sinusoidal endothelial cells (LSEC) which represent the first contact site for T-cell immigration into the liver. LSEC actively transferred basolaterally internalized CXCL12, CXCL9 and CXCL10 via clathrin- coated vesicles to CD4+ T cells leading to enhanced transmigration of CXCR4+ total CD4+ T cells and CXCR3+ effector/memory CD4+ T cells, respectively in vitro. LSEC-expressed CXCR4 mediated CXCL12 transport and blockage of endothelial CXCR4 inhibited CXCL12-dependent CD4+ T-cell transmigration. In contrast, CXCR3 was not involved in the endothelial transport of its ligands CXCL9 and CXCL10. The clathrin-specific inhibitor chlorpromazine blocked endothelial chemokine internalization and CD4+ T-cell transmigration in vitro as well as migration of CD4+ T cells into the inflamed liver in vivo. Moreover, hepatic accumulation of CXCR3+ CD4+ T cells during T cell-mediated hepatitis was strongly reduced after administration of chlorpromazine. These data demonstrate that LSEC actively provide perivascularly expressed homeostatic and inflammatory chemokines by CXCR4- and clathrin-dependent intracellular transport mechanisms thereby contributing to the hepatic recruitment of CD4+ T-cell populations during immune surveillance and liver inflammation

The disruption of proteostasis in neurodegenerative diseases

Cells count on surveillance systems to monitor and protect the cellular proteome which, besides being highly heterogeneous, is constantly being challenged by intrinsic and environmental factors. In this context, the proteostasis network (PN) is essential to achieve a stable and functional proteome. Disruption of the PN is associated with aging and can lead to and/or potentiate the occurrence of many neurodegenerative diseases (ND). This not only emphasizes the importance of the PN in health span and aging but also how its modulation can be a potential target for intervention and treatment of human diseases.info:eu-repo/semantics/publishedVersio

Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference

Interaction of two complementary fragments of the bovine spinal cord myelin basic protein with phosphatidylglycerol bilayers, studied by 2H and 31P NMR spectroscopy.

The interaction of two complementary fragments of myelin basic protein from bovine spinal cord with bilayers of dimyristoylphosphatidylglycerol has been studied by broad line 2H and 31P NMR. The fragments, produced by cleavage at the single tryptophan, consist of an N-terminal portion of molecular mass 12.6 kDa and a C-terminal portion of molecular mass 5.8 kDa. The phosphatidylglycerol lipid was deuterated at all three segments of the glycerol headgroup. The approximately linear dependence of the 2H quadrupole splittings and 31P chemical shift anisotropy on protein/lipid ratio in the complexes indicates that the lipids interacting with the protein fragments were in fast exchange on the NMR time scale (approximately 10(-4)-10(-5) s). The relative gradients of the dependence on protein/lipid ratio of both these parameters decrease with the size of the protein fragment and correlate reasonably well with both the net charge on the protein and the lipid binding stoichiometries in the absence of salt. The results are therefore consistent with a model in which the perturbation of the quadrupole splittings either is determined by the net surface potential or is constant for the different protein fragments. Either possibility is consistent with the reduced activity of the fragments relative to the whole protein

Terminal exon characterization with TECtool reveals an abundance of cell-specific isoforms

Sequencing of RNA 3' ends has uncovered numerous sites that do not correspond to the termination sites of known transcripts. Through their 3' untranslated regions, protein-coding RNAs interact with RNA-binding proteins and microRNAs, which regulate many properties, including RNA stability and subcellular localization. We developed the terminal exon characterization (TEC) tool ( http://tectool.unibas.ch ), which can be used with RNA-sequencing data from any species for which a genome annotation that includes sites of RNA cleavage and polyadenylation is available. We discovered hundreds of previously unknown isoforms and cell-type-specific terminal exons in human cells. Ribosome profiling data revealed that many of these isoforms were translated. By applying TECtool to single-cell sequencing data, we found that the newly identified isoforms were expressed in subpopulations of cells. Thus, TECtool enables the identification of previously unknown isoforms in well-studied cell systems and in rare cell types