Kidney Week

Abstract: SA-PO615

Dysregulated Glomerular Proteins in 1-Day-Old Col4a3 Knockout Mice

Session Information

• Genetic Kidney Diseases: Models, Mechanisms, and Therapies
  October 26, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Genetic Diseases of the Kidneys

• 1202 Genetic Diseases of the Kidneys: Non-Cystic

Authors

• De Gregorio, Vanessa Sara, Toronto General Hospital Research Institute, Toronto, Ontario, Canada

Vanessa Sara De Gregorio, MS

• Rana, Akanchaya, Princess Margaret Hospital Cancer Centre, Toronto, Ontario, Canada

Akanchaya Rana, MSc

• Caparali, Emine Bilge, Toronto General Hospital Research Institute, Toronto, Ontario, Canada

Emine Bilge Caparali, MD

• Ricardo, Samantha, Toronto General Hospital Research Institute, Toronto, Ontario, Canada

Samantha Ricardo

• Konvalinka, Ana, Toronto General Hospital Research Institute, Toronto, Ontario, Canada

Ana Konvalinka, MD, PhD

• Barua, Moumita, Toronto General Hospital Research Institute, Toronto, Ontario, Canada

Moumita Barua, MD

Background

Alport syndrome (AS) is a hereditary disorder caused by pathogenic variants in COL4A3, COL4A4 and/or COL4A5, encoding the α3α4α5 chains of type IV collagen typically expressed in the mature glomerular basement membrane (GBM) of the kidney. In AS due to truncating variants, podocytes do not form the α3α4α5(IV) basement membrane and instead, there is persistence of the flexible α1α1α2(IV) trimer normally present during development. To understand the earliest mechanisms of disease in AS, we elected to study glomerular changes in Col4a3 ^-/- (knockout; KO) mice at postnatal-day 1 (P1), when trimer switching is occurring.

Methods

P1 Col4a3 KO and wildtype mouse glomeruli were isolated using Dynabeads. Protein extracts from glomerular samples were subjected to mass spectrometry. Pathway analysis was performed using Gene Ontology and protein interactors were identified using STRING.

Results

More than 1,000 proteins from glomerular extracts were significantly dysregulated in P1 female KO compared to wildtype. In assessing protein-protein interactions between significantly dysregulated proteins, those with the greatest number of interactors included ACTB, GAPDH, ATP5B, EEF2, and SDHA. Over 70 pathways were identified as significantly different in female P1 KO compared to wildtype. Notably, these pathways were related to K63-linked deubiquitinase activity, alternative mRNA splicing, via the spliceosome, establishment or maintenance of transmembrane electrochemical gradient, actin filament binding, and NF-κB binding. In P1 male KO compared to wildtype, 17 proteins from glomerular extracts were identified as significantly dysregulated but no significantly different pathways were identified.

Conclusion

Pathways related to alternative splicing, cell maintenance, actin binding, and inflammation are dysregulated in the glomerulus at the earliest stage of disease in Col4a3 KO mice. These dysregulated pathways will be further explored to understand biological mechanisms in disease and to inform therapeutic development in the future.

Funding

• Private Foundation Support