Expression of Human Gaucher Disease Gene GBA Generates Neurodevelopmental Defects and ER Stress in Drosophila Eye Takahiro Suzuki 1,2. , Masami Shimoda 3. , Kumpei Ito 1,2 , Shuji Hanai 1 , Hidenobu Aizawa 1 , Tomoki Kato 1 , Kazunori Kawasaki 1 , Terumi Yamaguchi 3 , Hyung Don Ryoo 4 , Naoko Goto-Inoue 5 , Mitsutoshi Setou 6 , Shoji Tsuji 7 , Norio Ishida 1,2 * 1 National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki, Japan, 2 Graduate School of Life and Environmental Sciences, University of Tsukuba, Ibaraki, Japan, 3 National Institute of Agrobiological Sciences, Tsukuba, Ibaraki, Japan, 4 Department of Cell Biology, New York University School of Medicine, New York, New York, United States of America, 5 Graduate School of Health Promotion Sciences, Tokyo Metropolitan University, Tokyo, Japan, 6 Department of Cell Biology and Anatomy, Hamamatsu University School of Medicine, Shizuoka, Japan, 7 Department of Neurology, The University of Tokyo, Graduate School of Medicine, Tokyo, Japan Abstract Gaucher disease (GD) is the most common of the lysosomal storage disorders and is caused by defects in the GBA gene encoding glucocerebrosidase (GlcCerase). The accumulation of its substrate, glucocylceramide (GlcCer) is considered the main cause of GD. We found here that the expression of human mutated GlcCerase gene (hGBA) that is associated with neuronopathy in GD patients causes neurodevelopmental defects in Drosophila eyes. The data indicate that endoplasmic reticulum (ER) stress was elevated in Drosophila eye carrying mutated hGBAs by using of the ER stress markers dXBP1 and dBiP. We also found that Ambroxol, a potential pharmacological chaperone for mutated hGBAs, can alleviate the neuronopathic phenotype through reducing ER stress. We demonstrate a novel mechanism of neurodevelopmental defects mediated by ER stress through expression of mutants of human GBA gene in the eye of Drosophila. Citation: Suzuki T, Shimoda M, Ito K, Hanai S, Aizawa H, et al. (2013) Expression of Human Gaucher Disease Gene GBA Generates Neurodevelopmental Defects and ER Stress in Drosophila Eye. PLoS ONE 8(8): e69147. doi:10.1371/journal.pone.0069147 Editor: Andrea Dardis, University Hospital S. Maria della Misericordia, Udine, Italy Received February 14, 2013; Accepted June 12, 2013; Published August 2, 2013 Copyright: ß 2013 Suzuki et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by an internal grant from National Institute of Advanced Industrial Science and Technology (http://www.aist.go.jp/) and by a grant from Nihon Advanced Agri Corporation (http://www.adv-agri.co.jp/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: This work was funded in part by a grant from Nihon Advanced Agri Corporation. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials. * E-mail: n.ishida@aist.go.jp . These authors contributed equally to this work. Introduction Individuals with Gaucher disease (GD) are deficient in the membrane-associated lysosomal enzyme, glucocerebrosidase (GlcCerase). This reticuloendothelial storage disorder is clinically classified as types 1 (chronic, nonneuronopathic), 2 (acute, neuronopathic) and 3 (chronic, neuronopathic) [1]. Almost 300 mutations have been identified in the human GlcCerase gene (hGBA) [2]. The R120W mutation results in mild disease [3], whereas the L444P mutation is associated with neurological abnormalities [4–9] and the complex allele RecNciI (L444P + A456P + V460V) is involved in acute neurological abnormalities [7,9]. The general treatment of GD is to reduce the accumulation of stored glucocylceramide (GlcCer) substrate either by enhancing substrate degradation or by reducing its production. The main treatment strategy is intravenous enzyme replacement, which might partly restore a deficient enzymatic capacity [10]. However this strategy cannot prevent or treat neurological abnormalities, perhaps because GlcCerase cannot cross the blood–brain barrier [11] and therefore no strategies are currently available to treat the neurological abnormalities associated with GD. Mouse models of GD were generated [12] by creating a GBA null allele [13], a point mutated GBA allele [14] or a GBA conditional knockout [15]. These models based the study on the notion that GD phenotypes are caused by accumulated stored GlcCer. Therefore, mutations or deletions were constructed from the endogenous homologous genes of mouse genome. In some cases, GlcCerase variants are retained to various degrees in the endoplasmic reticulum (ER) as seen in cells of patients with GD [16]. These findings indicated that mutated GlcCerase itself is toxic, but this is yet to be confirmed at molecular level. Drosophila provides a flexible and powerful model with which to study neurodegenerative diseases [17–21] because most of the genetic pathways involved in normal development and diseases are conserved between Drosophila and mammals. Thus, understanding the molecular mechanisms of neurodegeneration in Drosophila might help to clarify human neurodegenerative processes [22]. Although several models for various neurodegenerative diseases such as Parkinson’s disease have been created [23], a Drosophila model of GD is not available. Here, we express mutated hGBA in the Drosophila eye using GMR-Gal4. We show that mutated hGBAs in particular, the RecNciI mutation that is associated with acute neurological PLOS ONE | www.plosone.org 1 August 2013 | Volume 8 | Issue 8 | e69147