Fabrication of GaSb Microlenses by Photo and E-Beam Lithography and Dry Etching

score: 0collation: 83-8

Nano-ZnO leads to tubulin macrotube assembly and actin bundling triggering cytoskeletal catastrophe and cell necrosis

Zinc is a crucial element in biology that plays chief catalytic, structural and protein regulatory roles. Excess cytoplasmic Zinc is toxic to the cells so there are cell-entry and intracellular buffering mechanisms that control intracellular Zinc disponibility. Tubulin and actin are two Zinc-scavenging proteins that are essential components of the cellular cytoskeleton implicated in cell division, migration and cellular architecture maintenance. Here we demonstrate how exposure to different ZnO nanostructures, namely ZnO commercial nanoparticles and custom-made ZnO nanowires, produce acute cytotoxic effects in human keratinocytes (HaCat) and epithelial cells (HeLa) triggering a dose-dependent cell retraction and collapse. We show how engulfed ZnO nanoparticles dissolve intracellularly, triggering actin filament bundling and structural changes in microtubules, transforming these highly dynamic 24nm diameter polymers into rigid macrotubes of tubulin, severely affecting cell proliferation and survival. Our results demostrate that nano-ZnO causes an acute cytoskeletal collapse that triggers necrosis, followed by a late reactive oxygen species (ROS)-dependent apoptotic process.This work has been supported by the Spanish ISCIII-MINECO under Projects ref. PI13/01074, AES 2013; FONDOS FEDER; MAT2012-38664-C02-01. We especially thank the IDIVAL for their support to LGH and the IDIVAL-Microscopy Unit for all the microscopy imaging

Identification of an Actin Binding Surface on Vinculin that Mediates Mechanical Cell and Focal Adhesion Properties

SummaryVinculin, a cytoskeletal scaffold protein essential for embryogenesis and cardiovascular function, localizes to focal adhesions and adherens junctions, connecting cell surface receptors to the actin cytoskeleton. While vinculin interacts with many adhesion proteins, its interaction with filamentous actin regulates cell morphology, motility, and mechanotransduction. Disruption of this interaction lowers cell traction forces and enhances actin flow rates. Although a model for the vinculin:actin complex exists, we recently identified actin-binding deficient mutants of vinculin outside sites predicted to bind actin and developed an alternative model to better define this actin-binding surface, using negative-stain electron microscopy (EM), discrete molecular dynamics, and mutagenesis. Actin-binding deficient vinculin variants expressed in vinculin knockout fibroblasts fail to rescue cell-spreading defects and reduce cellular response to external force. These findings highlight the importance of this actin-binding surface and provide the molecular basis for elucidating additional roles of this interaction, including actin-induced conformational changes that promote actin bundling

Decrease of blood anti-alpha 1,3 Galactose Abs levels in multiple sclerosis (MS) and clinically isolated syndrome (CIS) patients

International audienceThe etiology of multiple sclerosis (MS) remains elusive. Among the possible causes, the increase of anti-Neu5Gc antibodies during EBV primo-infection of Infectious mononucleosis (IMN) may damage the integrity of the blood-brain barrier facilitating the transfer of EBV-infected B cells and anti-EBV T cell clones in the brain. We investigated the change in titers of anti-Neu5Gc and anti-α1,3 Galactose antibodies in 49 IMN, in 76 MS, and 73 clinically isolated syndrome (CIS) patients, as well as age/gender-matched healthy individuals. Anti-Gal and anti-Neu5Gc are significantly increased during IMN (p=0.02 and p<1.10 respectively), but not in acute CMV primo-infection. We show that, whereas there was no change in anti-Neu5Gc in MS/CIS, the two populations exhibit a significant decrease in anti-Gal (combined p=2.7.10), in contrast with patients with non-MS/CIS central nervous system pathologies. Since anti-Gal result from an immunization against α1,3 Gal, lacking in humans but produced in the gut, our data suggest that CIS and MS patients have an altered microbiota or an altered response to this microbiotic epitope