title: Downregulation of alpha-galactosidase A upregulates CD77: functional impact for Fabry nephropathy.
abstract: Anderson-Fabry disease, an inherited deficiency in the lysosomal enzyme alpha-galactosidase A, is characterized by the progressive accumulation of globotriaosylceramide (Gb3), also known as CD77. We sought to clarify the pathogenesis of Fabry disease by establishing a cell model of this disorder. The expression of alpha-galactosidase A was transiently silenced by RNA interference in HK2 and primary human renal epithelial cells and stably silenced in HK2 cells by retroviral transfection with small hairpin RNA. All of the silenced cells had histological similarities to cells of patients with Fabry disease. The cells had reduced viability, significant accumulation of intracellular Gb3, and a modest but significant increase in membranous Gb3 expression compared to nonsilenced cells. When silenced HK2 cells were reconstituted with agalsidase-alpha, a protein used for enzyme replacement therapy, they decreased their membranous CD77 expression to levels indistinguishable from those of nonsilenced cells. Because plasma and urinary Gb3 levels are not reliable biomarkers for Fabry disease, our study suggests that membranous CD77 levels mirror Gb3 tissue load and that CD77 expression levels may be used to monitor the efficacy of enzyme replacement therapy.
authors.affiliation: First Department of Medicine, Johannes-Gutenberg University Mainz, Mainz, RLP, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Thomaidis
authors.forename: Manfred
authors.initials: M
authors.lastname: Relle
authors.forename: Mitra
authors.initials: M
authors.lastname: Golbas
authors.forename: Christoph
authors.initials: C
authors.lastname: Brochhausen
authors.forename: Peter R
authors.initials: PR
authors.lastname: Galle
authors.forename: Michael
authors.initials: M
authors.lastname: Beck
authors.forename: Andreas
authors.initials: A
authors.lastname: Schwarting
mesh_terms: D002460:Cell Line; D004847:Epithelial Cells / Q000473:pathology*; D000795:Fabry Disease / Q000209:etiology / Q000235:genetics* / Q000473:pathology; D005786:Gene Expression Regulation / Q000187:drug effects; D020868:Gene Silencing; D005915:Globosides / Q000096:biosynthesis*; D006801:Humans; D034741:RNA, Small Interfering / Q000494:pharmacology; D014281:Trihexosylceramides / Q000096:biosynthesis*; D000519:alpha-Galactosidase / Q000235:genetics*
chemical_list: D005915:Globosides; D034741:RNA, Small Interfering; D014281:Trihexosylceramides; C514780:globotrihexosylceramide; D000519:alpha-Galactosidase