Synaptotagmin-Mediated Bending of the Target Membrane Is a Critical Step in Ca2+-Regulated Fusion

SummaryDecades ago it was proposed that exocytosis involves invagination of the target membrane, resulting in a highly localized site of contact between the bilayers destined to fuse. The vesicle protein synaptotagmin-I (syt) bends membranes in response to Ca2+, but whether this drives localized invagination of the target membrane to accelerate fusion has not been determined. Previous studies relied on reconstituted vesicles that were already highly curved and used mutations in syt that were not selective for membrane-bending activity. Here, we directly address this question by utilizing vesicles with different degrees of curvature. A tubulation-defective syt mutant was able to promote fusion between highly curved SNARE-bearing liposomes but exhibited a marked loss of activity when the membranes were relatively flat. Moreover, bending of flat membranes by adding an N-BAR domain rescued the function of the tubulation-deficient syt mutant. Hence, syt-mediated membrane bending is a critical step in membrane fusion

Computational Relativistic Astrophysics With Adaptive Mesh Refinement: Testbeds

We have carried out numerical simulations of strongly gravitating systems based on the Einstein equations coupled to the relativistic hydrodynamic equations using adaptive mesh refinement (AMR) techniques. We show AMR simulations of NS binary inspiral and coalescence carried out on a workstation having an accuracy equivalent to that of a $1025^3$ regular unigrid simulation, which is, to the best of our knowledge, larger than all previous simulations of similar NS systems on supercomputers. We believe the capability opens new possibilities in general relativistic simulations.Comment: 7 pages, 16 figure

Frequency of Peripheral CD8+ T Cells Expressing Chemo-Attractant Receptors CCR1, 4 and 5 Increases in NPC Patients with EBV Clearance upon Radiotherapy

Radiotherapy (RT) is the standard-of-care for Epstein–Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC), where the post-RT clearance of plasma EBV DNA is prognostic. Currently, it is not known whether the post-RT clearance of plasma EBV DNA is related to the presence of circulating T-cell subsets. Blood samples from NPC patients were used to assess the frequency of T-cell subsets relating to differentiation, co-signaling and chemotaxis. Patients with undetectable versus detectable plasma EBV DNA levels post-RT were categorized as clearers vs. non-clearers. Clearers had a lower frequency of PD1+CD8+ T cells as well as CXCR3+CD8+ T cells during RT compared to non-clearers. Clearers exclusively showed a temporal increase in chemo-attractant receptors CCR1, 4 and/or 5, expressing CD8+ T cells upon RT. The increase in CCR-expressing CD8+ T cells was accompanied by a drop in naïve CD8+ T cells and an increase in OX40+CD8+ T cells. Upon stratifying these patients based on clinical outcome, the dynamics of CCR-expressing CD8+ T cells were in concordance with the non-recurrence of NPC. In a second cohort, non-recurrence associated with higher quantities of circulating CCL14 and CCL15. Collectively, our findings relate plasma EBV DNA clearance post-RT to T-cell chemotaxis, which requires validation in larger cohorts.</p

Maintenance treatment with quetiapine versus discontinuation after one year of treatment in patients with remitted first episode psychosis: randomised controlled trial

Objective To study rates of relapse in remitted patients with first episode psychosis who either continued or discontinued antipsychotic drugs after at least one year of maintenance treatment

Human Leukocyte Antigen (HLA) A*1101-restricted Epstein-Barr virus-specific T-cell receptor gene transfer to target Nasopharyngeal carcinoma

Infusing virus-specific T-cells is effective treatment for rare Epstein-Barr virus (EBV)-associated post-transplant lymphomas and more limited success has been reported using this approach to treat a far more common EBV-associated malignancy, Nasopharyngeal carcinoma (NPC). However, current approaches using EBV-transformed lymphoblastoid cell lines to reactivate EBV-specific T-cells for infusion take 2-3 months of in vitro culture and favour outgrowth of T-cells targeting viral antigens expressed within EBV+ lymphomas but not NPC. Here we explore T-cell receptor (TCR) gene transfer to rapidly and reliably generate T-cells specific for the NPC-associated viral protein LMP2. We cloned a HLA A*1101-restricted TCR, which would be widely applicable since 40% of NPC patients carry this HLA allele. Studying both wild-type and modified forms we have optimised expression of the TCR and demonstrated high avidity antigen-specific function (proliferation, cytotoxicity, cytokine release) in both CD8+ and CD4+ T-cells. The engineered T-cells also inhibited LMP2+ epithelial tumour growth in a mouse model. Furthermore, transduced T-cells from patients with advanced NPC lysed LMP2-expressing NPC cell lines. Therefore, using this approach, within a few days large numbers of high avidity LMP2-specific T-cells can be reliably generated to treat NPC, providing an ideal clinical setting to test TCR gene transfer without the risk of autoimmunity through targeting self-antigens

Otoferlin is a calcium sensor that directly regulates SNARE-mediated membrane fusion

Mutations in otoferlin are linked to human hearing loss. New research defines a function for this C2 domain–containing protein in synaptic vesicle exocytosis in cochlear hair cells

A recombinant modified vaccinia Ankara vaccine encoding Epstein-Barr virus (EBV) target antigens:a phase I trial in UK patients with EBV-positive cancer

Purpose: Epstein–Barr virus (EBV) is associated with several cancers in which the tumor cells express EBV antigens EBNA1 and LMP2. A therapeutic vaccine comprising a recombinant vaccinia virus, MVA-EL, was designed to boost immunity to these tumor antigens. A phase I trial was conducted to demonstrate the safety and immunogenicity of MVA-EL across a range of doses. Experimental Design: Sixteen patients in the United Kingdom (UK) with EBV-positive nasopharyngeal carcinoma (NPC) received three intradermal vaccinations of MVA-EL at 3-weekly intervals at dose levels between 5 × 107 and 5 × 108 plaque-forming units (pfu). Blood samples were taken at screening, after each vaccine cycle, and during the post-vaccination period. T-cell responses were measured using IFNγ ELISpot assays with overlapping EBNA1/LMP2 peptide mixes or HLA-matched epitope peptides. Polychromatic flow cytometry was used to characterize functionally responsive T-cell populations. Results: Vaccination was generally well tolerated. Immunity increased after vaccination to at least one antigen in 8 of 14 patients (7/14, EBNA1; 6/14, LMP2), including recognition of epitopes that vary between EBV strains associated with different ethnic groups. Immunophenotypic analysis revealed that vaccination induced differentiation and functional diversification of responsive T-cell populations specific for EBNA1 and LMP2 within the CD4 and CD8 compartments, respectively. Conclusions: MVA-EL is safe and immunogenic across diverse ethnicities and thus suitable for use in trials against different EBV-positive cancers globally as well as in South-East Asia where NPC is most common. The highest dose (5 × 108 pfu) is recommended for investigation in current phase IB and II trials. Clin Cancer Res; 20(19); 5009–22. ©2014 AACR

Genome Sequences of Mycobacteriophages Amgine, Amohnition, Bella96, Cain, DarthP, Hammy, Krueger, LastHope, Peanam, PhelpsODU, Phrank, SirPhilip, Slimphazie, and Unicorn

We report the genome sequences of 14 cluster K mycobacteriophages isolated using Mycobacterium smegmatis mc2155 as host. Four are closely related to subcluster K1 phages, and 10 are members of subcluster K6. The phage genomes span considerable sequence diversity, including multiple types of integrases and integration sites

The Future of the Correlated Electron Problem

The understanding of material systems with strong electron-electron interactions is the central problem in modern condensed matter physics. Despite this, the essential physics of many of these materials is still not understood and we have no overall perspective on their properties. Moreover, we have very little ability to make predictions in this class of systems. In this manuscript we share our personal views of what the major open problems are in correlated electron systems and we discuss some possible routes to make progress in this rich and fascinating field. This manuscript is the result of the vigorous discussions and deliberations that took place at Johns Hopkins University during a three-day workshop January 27, 28, and 29, 2020 that brought together six senior scientists and 46 more junior scientists. Our hope, is that the topics we have presented will provide inspiration for others working in this field and motivation for the idea that significant progress can be made on very hard problems if we focus our collective energies.Comment: 55 pages, 19 figure