title: Modeling Monogenic Human Nephrotic Syndrome in theDrosophilaGarland Cell Nephrocyte.
abstract: Steroid-resistant nephrotic syndrome is characterized by podocyte dysfunction.Drosophilagarland cell nephrocytes are podocyte-like cells and thus provide a potentialin vivomodel in which to study the pathogenesis of nephrotic syndrome. However, relevant pathomechanisms of nephrotic syndrome have not been studied in nephrocytes. Here, we discovered that twoDrosophilaslit diaphragm proteins, orthologs of the human genes encoding nephrin and nephrin-like protein 1, colocalize within a fingerprint-like staining pattern that correlates with ultrastructural morphology. Using RNAi and conditional CRISPR/Cas9 in nephrocytes, we found this pattern depends on the expression of both orthologs. Tracer endocytosis by nephrocytes required Cubilin and reflected size selectivity analogous to that of glomerular function. Using RNAi and tracer endocytosis as a functional read-out, we screenedDrosophilaorthologs of human monogenic causes of nephrotic syndrome and observed conservation of the central pathogenetic alterations. We focused on the coenzyme Q10(CoQ10) biosynthesis geneCoq2, the silencing of which disrupted slit diaphragm morphology. Restoration of CoQ10synthesis by vanillic acid partially rescued the phenotypic and functional alterations induced byCoq2-RNAi. Notably,Coq2colocalized with mitochondria, andCoq2silencing increased the formation of reactive oxygen species (ROS). Silencing ofND75, a subunit of the mitochondrial respiratory chain that controls ROS formation independently of CoQ10, phenocopied the effect ofCoq2-RNAi. Moreover, the ROS scavenger glutathione partially rescued the effects ofCoq2-RNAi. In conclusion,Drosophilagarland cell nephrocytes provide a model with which to study the pathogenesis of nephrotic syndrome, and ROS formation may be a pathomechanism ofCOQ2-nephropathy.
authors.affiliation: Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; tobias.hermle@childrens.harvard.edu friedhelm.hildebrandt@childrens.harvard.edu.
authors.forename: Tobias
authors.initials: T
authors.lastname: Hermle
authors.affiliation: Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Daniela A
authors.initials: DA
authors.lastname: Braun
authors.affiliation: Renal Division, University Medical Center Freiburg, Freiburg, Germany, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and.
authors.forename: Martin
authors.initials: M
authors.lastname: Helmstädter
authors.affiliation: Renal Division, University Medical Center Freiburg, Freiburg, Germany, Faculty of Medicine, University of Freiburg, Freiburg, Germany; and.|BIOSS Center for Biological Signalling Studies, Albert-Ludwigs-University Freiburg, Freiburg, Germany.
authors.forename: Tobias B
authors.initials: TB
authors.lastname: Huber
authors.affiliation: Division of Nephrology, Department of Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts; tobias.hermle@childrens.harvard.edu friedhelm.hildebrandt@childrens.harvard.edu.
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Hildebrandt
mesh_terms: D000818:Animals; D004330:Drosophila / Q000166:cytology*; D029721:Drosophila Proteins / Q000502:physiology; D006801:Humans; D008954:Models, Biological; D009404:Nephrotic Syndrome / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000502:physiology
chemical_list: D029721:Drosophila Proteins; D009419:Nerve Tissue Proteins; C066819:sli protein, Drosophila
keywords: COQ2; Drosophila; SRNS; garland cell; nephrocyte; nephrotic syndrome