Dataset Information

GAPVD1 and ANKFY1 Mutations Implicate RAB5 Regulation in Nephrotic Syndrome.

ABSTRACT: BACKGROUND:Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of CKD. The discovery of monogenic causes of SRNS has revealed specific pathogenetic pathways, but these monogenic causes do not explain all cases of SRNS. METHODS:To identify novel monogenic causes of SRNS, we screened 665 patients by whole-exome sequencing. We then evaluated the in vitro functional significance of two genes and the mutations therein that we discovered through this sequencing and conducted complementary studies in podocyte-like Drosophila nephrocytes. RESULTS:We identified conserved, homozygous missense mutations of GAPVD1 in two families with early-onset NS and a homozygous missense mutation of ANKFY1 in two siblings with SRNS. GAPVD1 and ANKFY1 interact with the endosomal regulator RAB5. Coimmunoprecipitation assays indicated interaction between GAPVD1 and ANKFY1 proteins, which also colocalized when expressed in HEK293T cells. Silencing either protein diminished the podocyte migration rate. Compared with wild-type GAPVD1 and ANKFY1, the mutated proteins produced upon ectopic expression of GAPVD1 or ANKFY1 bearing the patient-derived mutations exhibited altered binding affinity for active RAB5 and reduced ability to rescue the knockout-induced defect in podocyte migration. Coimmunoprecipitation assays further demonstrated a physical interaction between nephrin and GAPVD1, and immunofluorescence revealed partial colocalization of these proteins in rat glomeruli. The patient-derived GAPVD1 mutations reduced nephrin-GAPVD1 binding affinity. In Drosophila, silencing Gapvd1 impaired endocytosis and caused mistrafficking of the nephrin ortholog. CONCLUSIONS:Mutations in GAPVD1 and probably in ANKFY1 are novel monogenic causes of NS. The discovery of these genes implicates RAB5 regulation in the pathogenesis of human NS.

SUBMITTER: Hermle T

PROVIDER: S-EPMC6065084 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

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Publications

<i>GAPVD1</i> and <i>ANKFY1</i> Mutations Implicate RAB5 Regulation in Nephrotic Syndrome.

Hermle Tobias T Schneider Ronen R Schapiro David D Braun Daniela A DA van der Ven Amelie T AT Warejko Jillian K JK Daga Ankana A Widmeier Eugen E Nakayama Makiko M Jobst-Schwan Tilman T Majmundar Amar J AJ Ashraf Shazia S Rao Jia J Finn Laura S LS Tasic Velibor V Hernandez Joel D JD Bagga Arvind A Jalalah Sawsan M SM El Desoky Sherif S Kari Jameela A JA Laricchia Kristen M KM Lek Monkol M Rehm Heidi L HL MacArthur Daniel G DG Mane Shrikant S Lifton Richard P RP Shril Shirlee S Hildebrandt Friedhelm F

Journal of the American Society of Nephrology : JASN 20180629 8

<h4>Background</h4>Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of CKD. The discovery of monogenic causes of SRNS has revealed specific pathogenetic pathways, but these monogenic causes do not explain all cases of SRNS.<h4>Methods</h4>To identify novel monogenic causes of SRNS, we screened 665 patients by whole-exome sequencing. We then evaluated the <i>in vitro</i> functional significance of two genes and the mutations therein that we discovered through this sequencing and co ...[more]

PMID: 29959197

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Project description:BACKGROUND: Nephrotic syndrome is traditionally classified on the basis of the response to standard steroid treatment. Mutations in more than 24 genes have been associated with nephrotic syndrome in children, although the great majority of steroid-resistant cases have been attributed to mutations in three main genes: NPHS1, NPHS2 and WT1. The aims of this study were to identify mutations in these genes more frequently reported as mutated and to characterize each variation using different in silico prediction algorithms in order to understand their biological functions. METHODS: We performed direct sequence analysis of exons 8 and 9 of WT1, 8 exons of NPHS2 and 29 exons of NPHS1, including NPHS2 and NPHS1 intron-exon boundary sequences, as well as 700 bp of the 5' UTR from both genes in 27 steroid-resistant patients aged between 3 months and 18 years. RESULTS: Analysis of the NPHS2 gene revealed four missense mutations, one frameshift mutation and three variations in the 5' UTR. Four patients presented compound heterozygosis, and four other patients presented one heterozygous alteration only. WT1 and NPHS1 gene analysis did not reveal any mutations. DISCUSSION: This is the first study focusing on genetics of SRNS in Brazilian children. Identification of mutations is important because it could influence physicians' decision on patient treatment, as patients carrying mutations can be spared the side effects of immunosuppressive therapy and ultimately could be considered for kidney transplantation from a living donor. CONCLUSIONS: After molecular analysis of the genes more frequently reported as mutated in 27 steroid-resistant nephrotic syndrome patients, we identified NPHS2 mutations confirming the hereditary character of the kidney disease in only 14.8% of patients. Therefore, the next step is to perform a next generation sequencing based analysis of glomeluropathy-related panel of genes for the remaining patients in order to search for mutations in other genes related to steroid-resistant nephrotic syndrome.

Dataset Information

GAPVD1 and ANKFY1 Mutations Implicate RAB5 Regulation in Nephrotic Syndrome.

Publications

<i>GAPVD1</i> and <i>ANKFY1</i> Mutations Implicate RAB5 Regulation in Nephrotic Syndrome.

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