(P04-004-24) Quantitative Proteomics and Functional Enrichment Analyses of Changes in Renal Tubular Cell Proteome Induced by Ellagic Acid: Implications for Its Renoprotective Effects

Objectives: Ellagic acid (EA) is a bioactive polyphenol naturally found in many vegetables and fruits. Increasing evidence has documented its renoprotective effects but with still unclear mechanisms. This study thus employed a quantitative proteomics approach followed by functional enrichment analyses to unravel the molecular mechanisms underlying its beneficial effects in renal cells.

Methods: MDCK cells were treated with physiologic concentrations of EA (at 25-400 ng/ml) for 24 h to screen for its maximum concentration that caused no serious cytotoxicity. This optimal concentration was then used for label-free quantitative proteomics by nanoLC-ESI-Qq-TOF MS/MS. Prediction of protein-protein interactions was done via STRING version 11.5 (https://string-db.org). Functional enrichment analyses were performed via g:GOSt on g:Profiler (https://biit.cs.ut.ee/gprofiler/gost).

Results: Cell death analysis using flow cytometry showed that 400 ng/ml was the optimal concentration of EA in this study. Quantitative proteomics revealed 21 significantly altered (13 upregulated and 8 downregulated) proteins in the EA-treated cells as compared with the control cells. Among them, the increased levels of heat shock protein 90 and vinculin were successfully confirmed by Western blotting. Prediction of protein-protein interactions by K-means clustering algorithm revealed two clusters of the upregulated proteins and one cluster of the downregulated proteins. Functional enrichment analyses revealed that only the upregulated proteins showed functional relevance in positive regulation of cellular metabolic process, regulation of protein stability, cadherin binding, unfolded protein binding, cell adhesion molecule binding, ubiquitin protein ligase binding, ubiquitin-like protein ligase binding, protein folding chaperone, heat shock protein binding, enzyme binding, and MHC protein complex binding.

Conclusions: We report herein that EA induces changes in the levels of several proteins in renal cells. These significantly altered proteins, particularly the upregulated ones, play important roles in various biological processes and molecular functions, all of which are essential for maintaining cellular homeostasis. These data may, at least in part, explain the molecular mechanisms underlying the renoprotective effects of EA.

Funding Sources: N?A