ASN's Mission

To create a world without kidney diseases, the ASN Alliance for Kidney Health elevates care by educating and informing, driving breakthroughs and innovation, and advocating for policies that create transformative changes in kidney medicine throughout the world.

learn more

Contact ASN

1401 H St, NW, Ste 900, Washington, DC 20005

email@asn-online.org

202-640-4660

The Latest on X

Kidney Week

Abstract: SA-PO0624

Impaired Autophagy in Human Kidney Organoids of Autosomal Dominant Tubulointerstitial Kidney Disease

Session Information

Category: Genetic Diseases of the Kidneys

  • 1201 Genetic Diseases of the Kidneys: Monogenic Kidney Diseases

Authors

  • Gu, Chenjian, Washington University in St Louis School of Medicine, St. Louis, Missouri, United States
  • Sun, Zhao, The University of Texas at Dallas Department of Biological Sciences, Richardson, Texas, United States
  • Kidd, Kendrah O., Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
  • Bleyer, Anthony J., Wake Forest University School of Medicine, Winston-Salem, North Carolina, United States
  • Chen, Ying Maggie, Washington University in St Louis School of Medicine, St. Louis, Missouri, United States
Background

UMOD encoding uromodulin is a well-established causal gene for chronic kidney disease (CKD). Mutations in UMOD cause autosomal dominant tubulointerstitial kidney disease (ADTKD), a leading hereditary kidney disease and monogenic CKD characterized by progressive renal fibrosis. UMOD is largely expressed in the thick ascending limb (TAL) tubular epithelial cells, and UMOD p.H177-R185 del is the most prevalent mutation in ADTKD patients. Currently, no therapies are available to treat or halt the disease progression.

Methods

We generated human induced pluripotent stem cells (hiPSCs) by reprogramming dermal fibroblasts obtained from an ADTKD patient carrying the UMOD p.H177-R185 del and an unaffected family member. The mutant / WT hiPSCs were further differentiated to kidney organoids for 25 days. For the first time, we isolated TAL cells from the kidney organoids by using the Dynabeads magnetic bead conjugation system, whereby biotinylated, anti-UMOD antibody and Dynabeads Biotin Binder were employed. WB, IF staining and confocal microscopy were also utilized.

Results

ADTKD and WT kidney organoids containing TALs are successfully generated. IF staining of the organoids shows that WT UMOD is enriched at the apical membrane of TAL tubules, whereas the mutant UMOD exhibits diffuse cytoplasmic expression in TALs. Furthermore, in the isolated TALs, WB reveals elevation of the under-glycosylated form of the mutant UMOD due to endoplasmic reticulum retention. Mechanistic investigation shows defective autophagic clearance of the mutant UMOD, as demonstrated by accumulation of autophagy receptor p62 and LC3B-II in the isolated mutant TALs. Moreover, expression of positive regulators of autophagy, p-AMPK and FOXO3, is markedly reduced in the mutant TALs, further elucidating the molecular regulation of the dysfunctional autophagy. Notably, these results are reminiscent of findings noted in our previously CRISPR-generated mouse model carrying the same Umod deletion mutation (Nat. Commun. 2023).

Conclusion

We have successfully established patient-derived ADTKD kidney organoids. For the first time, we have validated autophagy deficiency in ADTKD-UMOD patients. These complementary ADTKD mouse and kidney organoid models are very valuable platforms for disease modeling, mechanism investigation and discovery of autophagy activators for ADTKD patients.

Funding

  • NIDDK Support

Digital Object Identifier (DOI)