Helicobacter pylori CagA Disrupts Epithelial Patterning by Activating Myosin Light Chain

Helicobacter pylori infection is a leading cause of ulcers and gastric cancer. We show that expression of the H. pylori virulence factor CagA in a model Drosophila melanogaster epithelium induces morphological disruptions including ectopic furrowing. We find that CagA alters the distribution and increases the levels of activated myosin regulatory light chain (MLC), a key regulator of epithelial integrity. Reducing MLC activity suppresses CagA-induced disruptions. A CagA mutant lacking EPIYA motifs (CagAEPISA) induces less epithelial disruption and is not targeted to apical foci like wild-type CagA. In a cell culture model in which CagAEPISA and CagA have equivalent subcellular localization, CagAEPISA is equally potent in activating MLC. Therefore, in our transgenic system, CagA is targeted by EPIYA motifs to a specific apical region of the epithelium where it efficiently activates MLC to disrupt epithelial integrity

The Role of Anorexia in Resistance and Tolerance to Infections in Drosophila

Infections initiate a signaling loop in which sick animals become anorexic, and the resulting change in diet alters the body's ability to fight infections in good and bad ways

Fast Gaussian Process Posterior Mean Prediction via Local Cross Validation and Precomputation

Gaussian processes (GPs) are Bayesian non-parametric models useful in a myriad of applications. Despite their popularity, the cost of GP predictions (quadratic storage and cubic complexity with respect to the number of training points) remains a hurdle in applying GPs to large data. We present a fast posterior mean prediction algorithm called FastMuyGPs to address this shortcoming. FastMuyGPs is based upon the MuyGPs hyperparameter estimation algorithm and utilizes a combination of leave-one-out cross-validation, batching, nearest neighbors sparsification, and precomputation to provide scalable, fast GP prediction. We demonstrate several benchmarks wherein FastMuyGPs prediction attains superior accuracy and competitive or superior runtime to both deep neural networks and state-of-the-art scalable GP algorithms.Comment: 9 pages content, 4 figures, 3 table

Identification of Genetic Modifiers of CagA-Induced Epithelial Disruption in Drosophila

Helicobacter pylori strains containing the CagA protein are associated with high risk of gastric diseases including atrophic gastritis, peptic ulcers, and gastric cancer. CagA is injected into host cells via a Type IV secretion system where it activates growth factor-like signaling, disrupts cell-cell junctions, and perturbs host cell polarity. Using a transgenic Drosophila model, we have shown that CagA expression disrupts the morphogenesis of epithelial tissues such as the adult eye. Here we describe a genetic screen to identify modifiers of CagA-induced eye defects. We determined that reducing the copy number of genes encoding components of signaling pathways known to be targeted by CagA, such as the epidermal growth factor receptor, modified the CagA-induced eye phenotypes. In our screen of just over half the Drosophila genome, we discovered 12 genes that either suppressed or enhanced CagA’s disruption of the eye epithelium. Included in this list are genes involved in epithelial integrity, intracellular trafficking, and signal transduction. We investigated the mechanism of one suppressor, encoding the epithelial polarity determinant and junction protein Coracle, which is homologous to the mammalian Protein 4.1. We found that loss of a single copy of coracle improved the organization and integrity of larval retinal epithelia expressing CagA, but did not alter CagA’s localization to cell junctions. Loss of a single copy of the coracle antagonist crumbs enhanced CagA-associated disruption of the larval retinal epithelium, whereas overexpression of crumbs suppressed this phenotype. Collectively, these results point to new cellular pathways whose disruption by CagA are likely to contribute to H. pylori-associated disease pathology

MUSCLE CELL REGENERATIVE POTENTIAL FOLLOWING AMINO ACID SUPPLEMENTATION IN TOTAL KNEE ARTHROPLASTY PATIENTS

N. Bigot1, E. Owen2, T. Kirkpartick2, A. Poluso2, M. Bremer2, L. Strycker3, K. Smolkowski3, B. Lantz4, S. Shah4, C. Mohler4, B. Jewett4, J. Muyskens1, H. Dreyer1 1University of Oregon; 2Slocum Research and Education Foundation; 3Oregon Research Institute;4Slocum Center for Orthopedics and Sports Center, Eugene, OR PURPOSE: More than 600,000 Americans receive total knee arthroplasty (TKA) annually. Our goal is to improve functional outcomes following TKA by mitigating the extensive muscle loss that occurs during the first two weeks post surgery. Previously, we showed that essential amino acid supplementation (EAAs) improves function and reduces muscle atrophy as measured by MRI. This study aimed to determine muscle cell-level changes related to regenerative potential in TKA patients receiving EAAs compared to Placebo. METHODS Using a double-blind Placebo-controlled randomized clinical trial, 39 older adults (age 50-80 y) having TKA were randomized to ingest either 20 g of EAA (n = 19) or Placebo (n = 20) 2x/d between meals for 1 wk before, and 6 wk after TKA. Bilateral muscle biopsies (vastus lateralis (VL)) were obtained prior to surgery and at 1 or 2 weeks post TKA. Histological analysis determined cross-sectional area (CSA) of VL cells (anti-laminin), number of myonuclei per muscle cell (DAPI), fiber type composition (anti-MHC1), and satellite cell number (anti-Pax7). In addition, we assayed for shifts in inflammatory (M1) vs regenerative (M2) macrophage populations. RESULTS: Our preliminary results reveal satellite cell numbers are elevated in the EAA group vs Placebo for Type I cells (0.127±.02 vs, 0.073±.01, respectively, p=.054) and Type II cells (0.084±.02 vs. 0.039±.01, p=.64) after just 7 days of twice-daily EAA prior to surgery. After surgery in the EAA group, satellite cell numbers were reduced relative to baseline for both Type I (-37%) and II (-27%) fibers (p\u3c0.05). No changes in the satellite cell populations were measured in either leg for the Placebo group. Muscle CSA was reduced (-12%) in the Placebo group in the operative leg (p =.017). The treatment group did not display the corresponding decrease in CSA (p =.098). M1 macrophage populations were reduced in the operative leg of the treatment group at 1-week post surgery (p =.017). No changes in macrophage populations were measured for the Placebo group. CONCLUSIONS: Our data suggest that amino acid supplementation may attenuate muscle atrophy through preservation of satellite cells and a reduction in inflammatory macrophage numbers. NIA:R01AG04640