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Abstract: FR-PO1032

TRPC6 Overexpression Mice Produced Proteinuria with Downregulated Podocyte Genes

Session Information

Category: Genetic Diseases of the Kidney

  • 1002 Genetic Diseases of the Kidney: Non-Cystic

Authors

  • Sun, Zi Jin, National University of Singapore , Singapore, Singapore
  • Zhang, Yaochun, National University of Singapore , Singapore, Singapore
  • Ng, Jun li, National University of Singapore , Singapore, Singapore
  • Liao, Ping, National Neuroscience Institute, Singapore, Singapore
  • Soong, Tuck wah, National University of Singapore , Singapore, Singapore
  • Chong, Siong-Chuan, National University of Singapore , Singapore, Singapore
  • Chan, Yiong Huak, National University of Singapore , Singapore, Singapore
  • Yap, Hui Kim, National University Hospital, Singapore, Singapore
  • Ng, Kar Hui, National University of Singapore , Singapore, Singapore
Background

Mutations in transient receptor potential channel-6 (TRPC6) can cause autosomal dominant FSGS. We have previously identified novel p.R68W TRPC6 gain-of-function mutation. We aim to study the disease-causing mechanism of p.R68W mutation.

Methods

Wild type (OEwt) and p.R68W (OEmut) TRPC6 were overexpressed in FVB/N mice by pronuclear microinjection. The albumin:creatinine ratios were obtained. Podocyte gene expressions were measured by reverse-transcription PCR and western blot analysis. Podocyte ultrastructural changes were assesssed by transmission electron microscopy and transgene localization was performed by immunogold staining. Statistical analysis was performed using Mann-Whitney U test.

Results

Over one third of both groups of overexpression mice had albuminuria, and lower body weights compared with control mice from 6 month. Interestingly, OEwt were significantly lighter compared with OEmut since 6.5 month. Kidney electron microscopy slices demonstrated extensive podocyte foot process effacement in both OE mice. Immunogold staining revealed TRPC6 in OEwt mice localized predominantly in the central cytoplasmic areas, whereas in OEmut, TRPC6 occurred predominantly at the peripheral and central parts of the foot processes. Quantitative PCR data showed that nephrin and podocin expressions were decreased in OE mice compared to wild-type, and to a greater degree in the OEwt compared to OEmut.

Conclusion

Our work suggests p.R68W mutation may affect TRPC6 intracellular trafficking and its interactions with the slit diaphragm proteins in the podocytes.

Funding

  • Government Support - Non-U.S.