Background: Scattered tubular-like cells (STCs) are dedifferentiated renal tubular cells endowed with progenitor-like characteristics to repair injured parenchymal cells. STCs may be damaged and rendered ineffective by renal artery stenosis (RAS), but the underlying processes remain unclear. We hypothesized that RAS alters the epigenetic landscape on DNA and the ensuing gene transcriptional profile of swine STCs.
Methods: CD24+/CD133+ STCs were isolated from pig kidneys after 10 weeks of RAS or sham (n = 3 each) and their whole 5-methylcytosine (5mC) and 5-hydroxymethylcytosine (5hmC) profiles were examined by 5mC and 5hmC immunoprecipitation sequencing (MeDIP-/hMeDIP-seq, respectively). A subsequent integrated (MeDIP/hMeDIP-seq/mRNA-seq) analysis was performed by comparing all online available gene sets using Gene Set Enrichment Analysis. Apoptosis, proteolysis, and mitochondrial structure and function were subsequently evaluated in vitro.
Results: Differential expression (DE) analysis revealed 239 genes with higher and 236 with lower 5mC levels and 275 genes with higher and 315 with lower 5hmC levels in RAS-STCs compared to Normal-STCs (fold change ≥1.4 or ≤0.7, p ≤ 0.05). Integrated MeDIP-/hMeDIP-seq/mRNA-seq analysis identified several overlapping (DE-5mC/mRNA and DE-5hmC/mRNA levels) genes primarily implicated in apoptosis, proteolysis, and mitochondrial functions. Furthermore, RAS-STCs exhibited decreased apoptosis, mitochondrial matrix density, and ATP production, and increased intracellular amino acid concentration and ubiquitin expression.
Conclusions: Renal ischemia induces epigenetic changes in apoptosis-, proteolysis-, and mitochondria-related genes, which correlate with alterations in the transcriptomic profile and corresponding function of swine STCs. These observations may contribute to developing novel targeted interventions to preserve the reparative potency of STCs in renal disease.
Keywords: epigenetics; mitochondria; renal artery stenosis; renal ischemia; scattered tubular-like cells.