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Drosophila melanogaster Mutated in its GBA1b Ortholog Recapitulates Neuronopathic Gaucher Disease

ABSTRACT: Gaucher disease (GD) results from mutations in the GBA1 gene, which encodes lysosomal glucocerebrosidase (GCase). The large number of mutations known to date in the gene lead to a heterogeneous disorder, which is divided into a non-neuronopathic, type 1 GD, and two neurological, type 2 and type 3, forms. We studied the two fly GBA1 orthologs, GBA1a and GBA1b. Each contains a Minos element insertion, which truncates its coding sequence. In the GBA1am/m flies, which express a mutant protein, missing 33 C-terminal amino acids, there was no decrease in GCase activity or substrate accumulation. However, GBA1bm/m mutant flies presented a significant decrease in GCase activity with concomitant substrate accumulation, which included C14:1 glucosylceramide and C14:0 glucosylsphingosine. GBA1bm/m mutant flies showed activation of the Unfolded Protein Response (UPR) and presented inflammation and neuroinflammation that culminated in development of a neuronopathic disease. Treatment with ambroxol did not rescue GCase activity or reduce substrate accumulation; however, it ameliorated UPR, inflammation and neuroinflammation, and increased life span. Our results highlight the resemblance between the phenotype of the GBA1bm/m mutant fly and neuronopathic GD and underlie its relevance in further GD studies as well as a model to test possible therapeutic modalities.

ORGANISM(S): Drosophila melanogaster

PROVIDER: GSE142144 | GEO | 2021/03/31

REPOSITORIES: GEO

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Project description:In non-neuronopathic type 1 Gaucher disease (GD1) mutations in GBA1 gene results in deficiency of glucocerebrosidase and the accumulation of glucocerebroside in lysosomes of mononuclear phagocytes. The metabolic defect leads to a complex phenotype involving the viscera, the bone marrow and the skeleton. However the prevailing macrophage-centric view of the disease does not explain emerging aspects of the disease such as hematological malignancies, autoimmune diathesis, ParkinsonM-bM-^@M-^Ys disease and osteoporosis poorly responsive to macrophage targeted enzyme therapy or anti-resorptive therapies. We developed a conditional KO mouse model of GD1 to delineate cells and pathways in GD1. By targeting the cells of the hematopoetic and mesenchymal cell lineages through an Mx1 promoter, we recapitulated human GD1. We show that, in addition to significant visceral and hematologic disease, GD1 mice show profound osteopenia due to a bone formation defect. Cytokine measurements, microarray analysis and cellular immunophenotyping together point to widespread dysfunction of macrophages and other immune cells together with a striking abnormality in thymic T-cell development. Our study provides the first direct evidence for the involvement of cell lineages other than mononuclear phagocytes, most notably osteoblasts and T cells, in the pathophysiology of the clinical spectrum of type 1 GD. These findings have important implications for treatment of GD1. We hypothesize that regulation of gene expression is different in Gaucher disease compared with the normal controls. This difference may even be evident in the different stages of this disease. In order to gain insight to the genes that are potentially involved in the development of Gaucher disease in its different clinical stages, exon-array is chosen for this genome-wide association studies. Mouse liver and spleen samples from normal control, GD with moderate to severe splenomegaly/hepatomegaly, together nine samples were chosen. The goal is to find out genes of which the expression may relate to the GD or the severity of GD and thus help identify genetic modifier genes that may contribute to the onset and development of Gaucher disease.