Nephrotic syndrome (NS) is one of the most frequent causes of End-Stage Renal Disease (ESRD) in children and young adults, but effective treatment is lacking, particularly for Steroid-Resistant Nephrotic Syndrome (SRNS). Rapid advances in DNA sequencing technology have led to the identification of large numbers of genetic variants that are potential causal factors for SRNS. However, lack of in vivo functional data for these candidate SRNS genes and their variants make it difficult to validate their roles in causing the disease. An animal model that carry the exact mutation found in patients for disease mechanism studies and testing of potential targeted therapies is in great demand. We have established a low-cost, high-efficiency Drosophila model system to generate essential functional data for candidate NS genes and variants, and to expedite the identification of novel NS genes. This novel kidney disease model system exploits the remarkable molecular, structural and functional equivalencies of Drosophila nephrocytes and human podocytes. We studied 40 known NS genes in nephrocytes and found that 85% of these genes play conserved roles in kidney cells from flies to humans. We also discovered underlying disease mechanisms by generating personalized fly NS models in which endogenous fly genes were functionally replaced by human homologs carrying patient-derived mutations. We also developed drug testing platform using these fly NS models, and successfully reversed the renal phenotype using targeted therapy informed by disease mechanism. In this renew proposal, we will use the powerful genetic tools in Drosophila to identify new renal genes involved in autophagy and cytoskeleton regulation. We will identify new nephrocyte cytoskeleton markers and components. We will also develop new personalized Drosophila models for candidate NS genes and novel genetic variants for known NS genes, as well as using the fly models to test potential targeted therapies. Our studies will provide the kidney disease research community with a low-cost high-efficiency model system to functionally validate NS associated genes and genetic variants, to identify novel NS genes, and to develop mechanism-based targeted therapies.

Public Health Relevance

Steroid-resistant nephrotic syndrome is a severe and significant form of kidney disease for which effective treatment options are lacking. Mutations in numerous genes involved in diverse processes are associated with the disease. The ability to identify causal genetic mutations in order to develop targeted therapies based on disease mechanism is essential. We developed a highly efficient Drosophila model system that enables identification and validation of genes and mutations causing steroid-resistant nephrotic syndrome, facilitates study of disease mechanisms, and provides a platform to test potential targeted therapies.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
7R01DK098410-07
Application #
9792376
Study Section
Pathobiology of Kidney Disease Study Section (PBKD)
Program Officer
Maric-Bilkan, Christine
Project Start
2014-04-10
Project End
2023-07-31
Budget Start
2019-09-17
Budget End
2020-07-31
Support Year
7
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of Maryland Baltimore
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Okamoto, Koji; Rausch, Jason W; Wakashin, Hidefumi et al. (2018) APOL1 risk allele RNA contributes to renal toxicity by activating protein kinase R. Commun Biol 1:188
Zhu, Jun-Yi; Fu, Yulong; Richman, Adam et al. (2017) A Personalized Model of COQ2 Nephropathy Rescued by the Wild-Type COQ2 Allele or Dietary Coenzyme Q10 Supplementation. J Am Soc Nephrol 28:2607-2617
Li, Jinliang; Das, Jharna R; Tang, Pingtao et al. (2017) Transmembrane TNF-?Facilitates HIV-1 Infection of Podocytes Cultured from Children with HIV-Associated Nephropathy. J Am Soc Nephrol 28:862-875
Zhu, Jun-Yi; Fu, Yulong; Richman, Adam et al. (2017) Validating Candidate Congenital Heart Disease Genes in Drosophila. Bio Protoc 7:
Zhu, Jun-Yi; Heidersbach, Amy; Kathiriya, Irfan S et al. (2017) The E3 ubiquitin ligase Nedd4/Nedd4L is directly regulated by microRNA 1. Development 144:866-875
Fu, Yulong; Zhu, Jun-Yi; Richman, Adam et al. (2017) A Drosophila model system to assess the function of human monogenic podocyte mutations that cause nephrotic syndrome. Hum Mol Genet 26:768-780
Fu, Yulong; Zhu, Jun-Yi; Zhang, Fujian et al. (2017) Comprehensive functional analysis of Rab GTPases in Drosophila nephrocytes. Cell Tissue Res 368:615-627
Zhu, Shasha; Han, Zhe; Luo, Yan et al. (2017) Molecular mechanisms of heart failure: insights from Drosophila. Heart Fail Rev 22:91-98
Fu, Yulong; Zhu, Jun-Yi; Richman, Adam et al. (2017) APOL1-G1 in Nephrocytes Induces Hypertrophy and Accelerates Cell Death. J Am Soc Nephrol 28:1106-1116
Zhu, Jun-Yi; Fu, Yulong; Nettleton, Margaret et al. (2017) High throughput in vivo functional validation of candidate congenital heart disease genes in Drosophila. Elife 6:

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