Peptide-Based PROTAC Degrader of CDA1 Suppresses Diabetic Kidney Disease

Background: Diabetic kidney disease (DKD) is a leading cause of mortality and morbidity in diabetes, representing a predominant cause of renal failure worldwide. The expression of cell division autoantigen 1 (CDA1) is elevated in the kidneys of diabetic animal models, which can promote renal fibrosis through the TGF-β signaling pathway. PROTAC is a protein depletion approach that utilizes small molecules or peptides to artificially bridge a protein of interest with E3 ligase for subsequent proteasomal degradation. We hypothesize that targeting CDA1 with peptide based PROTAC may be a promising approach for attenuation of renal fibrosis and DKD. Methods: To test the effect of a pharmacological approach of peptide-based PROTAC on the degradation of CDA1 and DKD progression, streptozotocin (STZ)-induced and db/db DKD mouse models were treated with different doses of the peptide-based PROTAC molecule CPV. The treated kidneys were collected and analyzed with H&E staining, immunofluorescence, immunohistochemistry staining and TUNEL assay. The expression of key factors in DKD were analyzed by WB and qRT-PCR analysis in DKD cells and kidneys. Results: We generated a new peptide-based PROTAC degrader, CPV, and demonstrated that treatment with the CPV induced ubiquitin-mediated degradation of CDA1 protein in DKD cells and kidneys, indicating by that the degradation of CDA1 could be reversed by co-treatment with proteasome inhibitor MG132. Among three doses tested, treatment with a dose of 5 ug/kg of CPV already could delay disease progression in two DKD mouse models as seen by a decrease of blood urea nitrogen (BUN) levels and urinary proteins, and an increase of serum albumin. In addition, treatment with CPV mitigated interstitial fibrosis and renal inflammation as seen by a decrease of the expression of profibrotic markers, including TGF-β, a-SMA and collagen 1, and proinflammatory factors, including TNF-a, MCP-1 and IL-1. It also reduced renal extracellular matrix (ECM) accumulation and glomerular injury index. Notably, no deleterious effects were observed in other organs. Conclusion: This study indicates that the peptide-based PROTAC degrader, CPV, can induce ubiquitin-mediated degradation of CDA1 protein in cells and kidneys from DKD mouse models, and suggest that peptide-based PROTAC therapy a safe and novel therapeutic strategy for the treatment of diabetic kidney disease. Funding: NIDDK Support, Other U.S. Government Support