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

Research output: Contribution to journalArticle (Academic Journal)peer-review

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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. A higher resolution version of the Graphical abstract is available as Supplementary information.

Original languageEnglish
Pages (from-to)2643-2656
Number of pages14
JournalPediatric Nephrology
Volume37
Issue number11
Early online date24 Feb 2022
DOIs
Publication statusE-pub ahead of print - 24 Feb 2022

Bibliographical note

Funding Information:
The UK Renal Rare Disease Registry (RaDaR) is funded by Kidney Research UK and British Kidney Patients’ Association. Drosophila work supported by Kidney Research UK and British Heart Foundation.

Funding Information:
We thank NIHR BioResource volunteers for their participation, and gratefully acknowledge NIHR BioResource centres, NHS Trusts and staff for their contribution. We thank the National Institute for Health Research, NHS Blood and Transplant, and Health Data Research UK as part of the Digital Innovation Hub Programme. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. The research was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London. Funding sources are Kids Kidney Research; Nephrotic Syndrome Trust; Kidney Research UK; National Institute for Health Research (NIHR, grant number RG65966) and Guys and St Thomas’ Hospital Charity.

Funding Information:
We thank Pauline Jones for her help with data and sample collection. We thank NIHR BioResource volunteers for their participation, and gratefully acknowledge NIHR BioResource centres, NHS Trusts and staff for their contribution. We thank the National Institute for Health Research, NHS Blood and Transplant, and Health Data Research UK as part of the Digital Innovation Hub Programme. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care. The research was supported by the National Institute for Health Research (NIHR) Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust and King's College London. Funding sources are Kids Kidney Research; Nephrotic Syndrome Trust; Kidney Research UK; National Institute for Health Research (NIHR, grant number RG65966) and Guys and St Thomas’ Hospital Charity. The UK Renal Rare Disease Registry (RaDaR) is funded by Kidney Research UK and British Kidney Patients’ Association. Drosophila work supported by Kidney Research UK and British Heart Foundation. A.B. is funded by Kidney Research UK (Non-clinical Post-doctoral Fellowship). This study was carried out on behalf of all the investigators in the UK National Study of Nephrotic Syndrome (NephroS). Additional funding was from MRC Precision Medicine grant number MR/RO13942/1, and from Nephrotic Syndrome Trust (NeST).

Funding Information:
Additional funding was from MRC Precision Medicine grant number MR/RO13942/1, and from Nephrotic Syndrome Trust (NeST).

Publisher Copyright:
© 2022, The Author(s).

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