title: Altered TFEB-mediated lysosomal biogenesis in Gaucher disease iPSC-derived neuronal cells.
abstract: Gaucher disease (GD) is caused by mutations in the GBA1 gene, which encodes the lysosomal enzyme glucocerebrosidase (GCase). The severe forms of GD are associated with neurodegeneration with either rapid (Type 2) or slow progression (Type 3). Although the neurodegenerative process in GD has been linked to lysosomal dysfunction, the mechanisms involved are largely unknown. To identify the lysosomal alterations in GD neurons and uncover the mechanisms involved, we used induced pluripotent stem cells (iPSCs) derived from patients with GD. In GD iPSC-derived neuronal cells (iPSC-NCs), GBA1 mutations caused widespread lysosomal depletion, and a block in autophagic flux due to defective lysosomal clearance of autophagosomes. Autophagy induction by rapamycin treatment in GD iPSC-NCs led to cell death. Further analysis showed that in GD iPSC-NCs, expression of the transcription factor EB (TFEB), the master regulator of lysosomal genes, and lysosomal gene expression, were significantly downregulated. There was also reduced stability of the TFEB protein and altered lysosomal protein biosynthesis. Treatment of mutant iPSC-NCs with recombinant GCase (rGCase) reverted the lysosomal depletion and autophagy block. The effect of rGCase on restoring lysosomal numbers in mutant cells was enhanced in the presence of overexpressed TFEB, but TFEB overexpression alone did not reverse the lysosomal depletion phenotype. Our results suggest that GBA1 mutations interfere with TFEB-mediated lysosomal biogenesis, and that the action of GCase in maintaining a functioning pool of lysosomes is exerted in part through TFEB. The lysosomal alterations described here are likely to be a major determinant in GBA1-associated neurodegeneration.
authors.affiliation: Department of Microbiology and Immunology.
authors.forename: Ola
authors.initials: O
authors.lastname: Awad
authors.affiliation: Department of Anesthesiology.
authors.forename: Chinmoy
authors.initials: C
authors.lastname: Sarkar
authors.affiliation: Department of Microbiology and Immunology.
authors.forename: Leelamma M
authors.initials: LM
authors.lastname: Panicker
authors.affiliation: Department of Microbiology and Immunology.
authors.forename: Diana
authors.initials: D
authors.lastname: Miller
authors.affiliation: Buck Institute for Age Research, Novato, CA, USA.
authors.forename: Xianmin
authors.initials: X
authors.lastname: Zeng
authors.affiliation: Department of Microbiology and Immunology.
authors.forename: Judi A
authors.initials: JA
authors.lastname: Sgambato
authors.affiliation: Department of Anesthesiology, Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, USA and.
authors.forename: Marta M
authors.initials: MM
authors.lastname: Lipinski
authors.affiliation: Department of Microbiology and Immunology, rfeldman@som.umaryland.edu.
authors.forename: Ricardo A
authors.initials: RA
authors.lastname: Feldman
mesh_terms: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000378:metabolism*; D002454:Cell Differentiation; D005776:Gaucher Disease / Q000378:metabolism / Q000503:physiopathology*; D005962:Glucosylceramidase / Q000235:genetics*; D057026:Induced Pluripotent Stem Cells / Q000502:physiology; D008247:Lysosomes / Q000378:metabolism / Q000502:physiology*; D009154:Mutation; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D001678:Organelle Biogenesis
chemical_list: D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; C064972:TFEB protein, human; D005962:Glucosylceramidase