Multi-ancestry study of blood lipid levels identifies four loci interacting with physical activity

Loss of 4E-BP1 expression has been linked to cancer progression and resistance to mTOR inhibitors, but the mechanism underlying 4E-BP1 downregulation in tumors remains unclear. Here we identify Snail as a strong transcriptional repressor of 4E-BP1. We find that 4E-BP1 expression inversely correlates with Snail level in cancer cell lines and clinical specimens. Snail binds to three E-boxes present in the human 4E-BP1 promoter to repress transcription of 4E-BP1. Ectopic expression of Snail in cancer cell lines lacking Snail profoundly represses 4E-BP1 expression, promotes cap-dependent translation in polysomes, and reduces the anti-proliferative effect of mTOR kinase inhibitors. Conversely, genetic and pharmacological inhibition of Snail function restores 4E-BP1 expression and sensitizes cancer cells to mTOR kinase inhibitors by enhancing 4E-BP1-mediated translation-repressive effect on cell proliferation and tumor growth. Our study reveals a critical Snail-4E-BP1 signaling axis in tumorigenesis, and provides a rationale for targeting Snail to improve mTOR-targeted therapies

Bioactive porcine matrices in heart valve tissue engineering

Background: Platelet-gel (PG) as a storage vehicle of growth factors, can be considered for the application of growth factors in combination with mesenchymal stem cells (MSCs) to accelerate tissue regeneration and repair. Moreover, the addition of bioactive factors to porcine aortic valves could result in a more rapid repopulation and matrix synthesis in vitro and, in turn, optimize scaffold incorporation in vivo. The aim of this study was to evaluate the influence of different PG concentrations on in vitro ovine mesenchymal stem cell (oMSC) proliferation, migration and invasion. Moreover, the effect of PG on the repopulation of porcine aortic matrices was investigated. Methods: oMSCs were isolated from bone marrow, expanded and differentiated to adipose tissue, cartilage and bone. oMSCs were exposed to different concentrations of supernatant (0-2x106 plt/mL). After a culture period of 72 hours, cellular proliferation was evaluated by an MTS assay. oMSC motility and invasiveness were assayed using a Boyden chamber. Decellularized porcine aortic valve matrices were incubated with the PG. Release of growth factors from the matrices was evaluated by ELISA. MSC repopulation in vitro was evaluated after 3 to 7 days by light microscopy. Results: oMSCs were shown to display the trilineage differentiation potential. The supernatant was able to stimulate cell proliferation already at a minimum concentration of 8x104plt/mL. Increasing platelet concentrations (<5x105 plt/mL) significantly increased oMSC proliferation, motility and invasiveness in a dose-dependent matter. Higher platelet concentrations (5x105 – 1x106 plt/mL) did not stimulate these processes any further since a plateau was reached. At the highest concentrations, there was a tendency to an inversion in the effect on proliferation, migration and invasion with values similar to those of untreated control cells. PG-incubated matrices showed a release of growth factors. oMSC density on these scaffolds increased significantly after 3-7 days compared to non-incubated control matrices. Conclusion: Incubating a decellularized porcine aortic valve with a PG concentrate creates a bioactive matrix. However, further fine-tuning of the PG concentration is necessary to take full advantage of platelet growth factor interaction within the aortic valve matrix in order to optimize cellular repopulation

Studies on the Essential Intramolecular Interaction Between the A1 and A2 Domains of von Willebrand Factor

Haemostasis depends on the balanced participation of von Willebrand factor (vWF), a large multimeric and multidomain glycoprotein with essential role during the initial steps of blood clotting. Mature vWF circulates in plasma with the form of multimers comprised of several domains with diverse functions. More specifically, the A1 domain of vWF plays crucial role in haemostasis, regulating the mechanism of platelet adhesion in sites of vascular injury while A2 domain regulates the normal turnover of vWF. Recent studies have implied that an intramolecular interaction between A1 and A2 domains exists, which prevents platelets adhesion and subsequently inhibits the initial step of the blood coagulation mechanism. In an effort to elucidate the essential nature of the interaction between these two domains, we produced and purified the corresponding recombinant unmodified polypeptides. The secondary structure of the two domains was studied individually and as a mixture using circular dichroism spectroscopy. The observed interaction was verified by ELISA competition assays using antibodies and their ability to form productive interactions was further characterized kinetically. In silico analysis (docking and molecular dynamics simulations) of the A1-A2 binding indicated three possible structural models highlighting the crucial, for this interaction, region