Centro Of Diagnostica Genetica E Biochimica Delle Malattie Metaboliche

Genova, Italy

Centro Of Diagnostica Genetica E Biochimica Delle Malattie Metaboliche

Genova, Italy

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PubMed | Hebrew University of Jerusalem, Tel Aviv University and Centro Of Diagnostica Genetica E Biochimica Delle Malattie Metaboliche
Type: | Journal: Blood cells, molecules & diseases | Year: 2016

Chronic presence of mutant, misfolded proteins in the endoplasmic reticulum (ER) initiates ER stress and induces the Unfolded Protein Response (UPR). In Gaucher disease (GD), resulting from mutations in the GBA1 gene, encoding lysosomal acid -glucocerebrosidase (GCase), a certain fraction of the mutant variants is retained in the ER and activates the UPR. We have previously shown UPR activation in GD derived fibroblasts, in fibroblasts that derived from carriers of GD mutations and in Drosophila models of carriers of GD mutations. In the present work we extended our studies to include a large collection of fibroblasts, EBV-transformed B-cells and white blood cells (WBCs) that derived from GD patients. The results showed UPR activation in all tested cells. They also indicated that transcription of the GBA1 gene is upregulated through activation of the UPR-induced CHOP transcription factor. Transcription of the MAN2B gene, encoding alpha-mannosidase and of the ACP gene, encoding acid phosphatase was also elevated presumably through CHOP activation. Our results highlight the existence of chronic stress in GD derived cells due to the presence of ER-retained mutant GCase, which leads to upregulation of GBA1 expression.


Maor G.,Tel Aviv University | Rencus-Lazar S.,Tel Aviv University | Filocamo M.,Centro Of Diagnostica Genetica E Biochimica Delle Malattie Metaboliche | Steller H.,Howard Hughes Medical Institute | And 2 more authors.
Orphanet Journal of Rare Diseases | Year: 2013

Background: In Gaucher disease (GD), resulting from mutations in the GBA gene, mutant β-glucocerebrosidase (GCase) molecules are recognized as misfolded in the endoplasmic reticulum (ER). They are retrotranslocated to the cytoplasm, where they are ubiquitinated and undergo proteasomal degradation in a process known as the ER Associated Degradation (ERAD). We have shown in the past that the degree of ERAD of mutant GCase correlates with GD severity.Persistent presence of mutant, misfolded protein molecules in the ER leads to ER stress and evokes the unfolded protein response (UPR). Methods. We investigated the presence of UPR in several GD models, using molecular and behavioral assays. Results: Our results show the existence of UPR in skin fibroblasts from GD patients and carriers of GD mutations. We could recapitulate UPR in two different Drosophila models for carriers of GD mutations: flies heterozygous for the endogenous mutant GBA orthologs and flies expressing the human N370S or L444P mutant GCase variants. We encountered early death in both fly models, indicating the deleterious effect of mutant GCase during development. The double heterozygous flies, and the transgenic flies, expressing mutant GCase in dopaminergic/serotonergic cells developed locomotion deficit. Conclusion: Our results strongly suggest that mutant GCase induces the UPR in GD patients as well as in carriers of GD mutations and leads to development of locomotion deficit in flies heterozygous for GD mutations. © 2013 Maor et al.; licensee BioMed Central Ltd.


Maor G.,Tel Aviv University | Filocamo M.,Centro Of Diagnostica Genetica E Biochimica Delle Malattie Metaboliche | Horowitz M.,Tel Aviv University
Human Molecular Genetics | Year: 2013

Inability to properly degrade unfolded or misfolded proteins in the endoplasmic reticulum (ER) leads to ER stress and unfolded protein response. This is particularly important in cases of diseases in which the mutant proteins undergo ER-associated degradation (ERAD), as in Gaucher disease (GD). GD is a genetic, autosomal recessive disease that results from mutations in the GBA1 gene, encoding the lysosomal enzyme acid β-glucocerebrosidase (GCase). We have shown that mutant GCase variants undergo ERAD, the degree of which is a major determinant of disease severity. Most ERAD substrates undergo polyubiquitination and proteasomal degradation. Therefore, one expects that mutant GCase variants are substrates for several E3 ubiquitin ligases in different cells. We tested the possibility that ITCH, a known E3 ubiquitin ligase, with a pivotal role in proliferation and differentiation of the skin, recognizes mutant GCase variants and mediates their polyubiquitination and degradation. Our results strongly suggest that ITCH interacts with mutant GCase variants and mediates their lysine 48 polyubiquitination and degradation. © The Author 2012. Published by Oxford University Press. All rights reserved.


Bendikov-Bar I.,Tel Aviv University | Maor G.,Tel Aviv University | Filocamo M.,Centro Of Diagnostica Genetica E Biochimica Delle Malattie Metaboliche | Horowitz M.,Tel Aviv University
Blood Cells, Molecules, and Diseases | Year: 2013

Gaucher disease (GD) is characterized by accumulation of glucosylceramide in lysosomes due to mutations in the GBA1 gene encoding the lysosomal hydrolase β-glucocerebrosidase (GCase). The disease has a broad spectrum of phenotypes, which were divided into three different Types; Type 1 GD is not associated with primary neurological disease while Types 2 and 3 are associated with central nervous system disease. GCase molecules are synthesized on endoplasmic reticulum (ER)-bound polyribosomes, translocated into the ER and following modifications and correct folding, shuttle to the lysosomes. Mutant GCase molecules, which fail to fold correctly, undergo ER associated degradation (ERAD) in the proteasomes, the degree of which is one of the factors that determine GD severity.Several pharmacological chaperones have already been shown to assist correct folding of mutant GCase molecules in the ER, thus facilitating their trafficking to the lysosomes. Ambroxol, a known expectorant, is one such chaperone. Here we show that ambroxol increases both the lysosomal fraction and the enzymatic activity of several mutant GCase variants in skin fibroblasts derived from Type 1 and Type 2 GD patients. © 2012 Elsevier Inc..

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