Exploring the relevance of NUP93 variants in steroid-resistant nephrotic syndrome using next generation sequencing and a fly kidney model

Agnieszka Bierzynska, Katherine Bull, Sara Miellet, Philip Dean, Chris Neal, Elizabeth Colby, Hugh J. McCarthy, Shivaram Hegde, Manish D. Sinha, Carmen Bugarin Diz, Kathleen Stirrups, Karyn Megy, Rutendo Mapeta, Chris Penkett, Sarah Marsh, Natalie Forrester, Maryam Afzal, Hannah Stark, Nihr BioResource, Maggie WilliamsGavin I. Welsh, Ania B. Koziell, Paul S. Hartley, Moin A. Saleem*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)
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Abstract

Background: Variants in genes encoding nuclear pore complex (NPC) proteins are a newly identified cause of paediatric steroid-resistant nephrotic syndrome (SRNS). Recent reports describing NUP93 variants suggest these could be a significant cause of paediatric onset SRNS. We report NUP93 cases in the UK and demonstrate in vivo functional effects of Nup93 depletion in a fly (Drosophila melanogaster) nephrocyte model. Methods: Three hundred thirty-seven paediatric SRNS patients from the National cohort of patients with Nephrotic Syndrome (NephroS) were whole exome and/or whole genome sequenced. Patients were screened for over 70 genes known to be associated with Nephrotic Syndrome (NS). D. melanogaster Nup93 knockdown was achieved by RNA interference using nephrocyte-restricted drivers. Results: Six novel homozygous and compound heterozygous NUP93 variants were detected in 3 sporadic and 2 familial paediatric onset SRNS characterised histologically by focal segmental glomerulosclerosis (FSGS) and progressing to kidney failure by 12 months from clinical diagnosis. Silencing of the two orthologs of human NUP93 expressed in D. melanogaster, Nup93-1, and Nup93-2 resulted in significant signal reduction of up to 82% in adult pericardial nephrocytes with concomitant disruption of NPC protein expression. Additionally, nephrocyte morphology was highly abnormal in Nup93-1 and Nup93-2 silenced flies surviving to adulthood. Conclusion: We expand the spectrum of NUP93 variants detected in paediatric onset SRNS and demonstrate its incidence within a national cohort. Silencing of either D. melanogaster Nup93 ortholog caused a severe nephrocyte phenotype, signaling an important role for the nucleoporin complex in podocyte biology. Graphical Abstract: A higher resolution version of the Graphical abstract is available as Supplementary information[Figure not available: see fulltext.]

Original languageEnglish
Pages (from-to)2643-2656
Number of pages14
JournalPediatric Nephrology
Volume37
Issue number11
Early online date24 Feb 2022
DOIs
Publication statusPublished - Nov 2022

Keywords

  • FSGS
  • Nephrocyte
  • NUP93
  • Podocyte
  • SRNS

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