Elevated Dkk1 Mediates Downregulation of the Canonical Wnt Pathway and Lysosomal Loss in an iPSC Model of Neuronopathic Gaucher Disease
Gaucher Disease (GD), which is the most common lysosomal storage disorder, is caused by bi-allelic mutations in <i>GBA1</i>—a gene that encodes the lysosomal hydrolase β-glucocerebrosidase (GCase). The neuronopathic forms of GD (nGD) are characterized by severe neurological abnormalities...
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doaj-fe5afce2d5414e198f3d190ef227faa82020-12-04T00:02:36ZengMDPI AGBiomolecules2218-273X2020-12-01101630163010.3390/biom10121630Elevated Dkk1 Mediates Downregulation of the Canonical Wnt Pathway and Lysosomal Loss in an iPSC Model of Neuronopathic Gaucher DiseaseManasa P. Srikanth0Ricardo A. Feldman1Department of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, MD 21201, USADepartment of Microbiology and Immunology, School of Medicine, University of Maryland, Baltimore, MD 21201, USAGaucher Disease (GD), which is the most common lysosomal storage disorder, is caused by bi-allelic mutations in <i>GBA1</i>—a gene that encodes the lysosomal hydrolase β-glucocerebrosidase (GCase). The neuronopathic forms of GD (nGD) are characterized by severe neurological abnormalities that arise during gestation or early in infancy. Using GD-induced pluripotent stem cell (iPSC)-derived neuronal progenitor cells (NPCs), we have previously reported that neuronal cells have neurodevelopmental defects associated with the downregulation of canonical Wnt signaling. In this study, we report that GD NPCs display elevated levels of Dkk1, which is a secreted Wnt antagonist that prevents receptor activation. Dkk1 upregulation in mutant NPCs resulted in an increased degradation of β-catenin, and there was a concomitant reduction in lysosomal numbers. Consistent with these results, incubation of the mutant NPCs with recombinant Wnt3a (rWnt3a) was able to outcompete the excess Dkk1, increasing β-catenin levels and rescuing lysosomal numbers. Furthermore, the incubation of WT NPCs with recombinant Dkk1 (rDkk1) phenocopied the mutant phenotype, recapitulating the decrease in β-catenin levels and lysosomal depletion seen in nGD NPCs. This study provides evidence that downregulation of the Wnt/β-catenin pathway in nGD neuronal cells involves the upregulation of Dkk1. As Dkk1 is an extracellular Wnt antagonist, our results suggest that the deleterious effects of Wnt/β-catenin downregulation in nGD may be ameliorated by the prevention of Dkk1 binding to the Wnt co-receptor LRP6, pointing to Dkk1 as a potential therapeutic target for <i>GBA1</i>-associated neurodegeneration.https://www.mdpi.com/2218-273X/10/12/1630Gaucher DiseaseWnt/β-cateninDkk1Wnt3alysosomesiPSC |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Manasa P. Srikanth Ricardo A. Feldman |
spellingShingle |
Manasa P. Srikanth Ricardo A. Feldman Elevated Dkk1 Mediates Downregulation of the Canonical Wnt Pathway and Lysosomal Loss in an iPSC Model of Neuronopathic Gaucher Disease Biomolecules Gaucher Disease Wnt/β-catenin Dkk1 Wnt3a lysosomes iPSC |
author_facet |
Manasa P. Srikanth Ricardo A. Feldman |
author_sort |
Manasa P. Srikanth |
title |
Elevated Dkk1 Mediates Downregulation of the Canonical Wnt Pathway and Lysosomal Loss in an iPSC Model of Neuronopathic Gaucher Disease |
title_short |
Elevated Dkk1 Mediates Downregulation of the Canonical Wnt Pathway and Lysosomal Loss in an iPSC Model of Neuronopathic Gaucher Disease |
title_full |
Elevated Dkk1 Mediates Downregulation of the Canonical Wnt Pathway and Lysosomal Loss in an iPSC Model of Neuronopathic Gaucher Disease |
title_fullStr |
Elevated Dkk1 Mediates Downregulation of the Canonical Wnt Pathway and Lysosomal Loss in an iPSC Model of Neuronopathic Gaucher Disease |
title_full_unstemmed |
Elevated Dkk1 Mediates Downregulation of the Canonical Wnt Pathway and Lysosomal Loss in an iPSC Model of Neuronopathic Gaucher Disease |
title_sort |
elevated dkk1 mediates downregulation of the canonical wnt pathway and lysosomal loss in an ipsc model of neuronopathic gaucher disease |
publisher |
MDPI AG |
series |
Biomolecules |
issn |
2218-273X |
publishDate |
2020-12-01 |
description |
Gaucher Disease (GD), which is the most common lysosomal storage disorder, is caused by bi-allelic mutations in <i>GBA1</i>—a gene that encodes the lysosomal hydrolase β-glucocerebrosidase (GCase). The neuronopathic forms of GD (nGD) are characterized by severe neurological abnormalities that arise during gestation or early in infancy. Using GD-induced pluripotent stem cell (iPSC)-derived neuronal progenitor cells (NPCs), we have previously reported that neuronal cells have neurodevelopmental defects associated with the downregulation of canonical Wnt signaling. In this study, we report that GD NPCs display elevated levels of Dkk1, which is a secreted Wnt antagonist that prevents receptor activation. Dkk1 upregulation in mutant NPCs resulted in an increased degradation of β-catenin, and there was a concomitant reduction in lysosomal numbers. Consistent with these results, incubation of the mutant NPCs with recombinant Wnt3a (rWnt3a) was able to outcompete the excess Dkk1, increasing β-catenin levels and rescuing lysosomal numbers. Furthermore, the incubation of WT NPCs with recombinant Dkk1 (rDkk1) phenocopied the mutant phenotype, recapitulating the decrease in β-catenin levels and lysosomal depletion seen in nGD NPCs. This study provides evidence that downregulation of the Wnt/β-catenin pathway in nGD neuronal cells involves the upregulation of Dkk1. As Dkk1 is an extracellular Wnt antagonist, our results suggest that the deleterious effects of Wnt/β-catenin downregulation in nGD may be ameliorated by the prevention of Dkk1 binding to the Wnt co-receptor LRP6, pointing to Dkk1 as a potential therapeutic target for <i>GBA1</i>-associated neurodegeneration. |
topic |
Gaucher Disease Wnt/β-catenin Dkk1 Wnt3a lysosomes iPSC |
url |
https://www.mdpi.com/2218-273X/10/12/1630 |
work_keys_str_mv |
AT manasapsrikanth elevateddkk1mediatesdownregulationofthecanonicalwntpathwayandlysosomallossinanipscmodelofneuronopathicgaucherdisease AT ricardoafeldman elevateddkk1mediatesdownregulationofthecanonicalwntpathwayandlysosomallossinanipscmodelofneuronopathicgaucherdisease |
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1724401064836333568 |