Renal ischemia alters expression of mitochondria-related genes and impairs mitochondrial structure and function in swine scattered tubular-like cells

Scattered tubular-like cells (STCs) are dedifferentiated surviving tubular epithelial cells that repair neighboring injured cells. Experimental renal artery stenosis (RAS) impairs STC reparative potency by inducing mitochondrial injury, but the exact mechanisms of mitochondrial damage remains unknown. We hypothesized that RAS alters expression of mitochondria-related genes, contributing to mitochondrial structural damage and dysfunction in swine STCs. CD24+/CD133+ STCs were isolated from pig kidneys after 10 weeks of RAS or sham (n=3 each). mRNA sequencing was performed and nuclear-DNA (nDNA) encoded mitochondrial genes and mitochondrial-DNA (mtDNA) encoded genes were identified. Mitochondrial structure, ATP generation, biogenesis, and expression of mitochondria-associated microRNAs (mitomiRs) were also assessed. There were 96 nDNA-encoded mitochondrial genes upregulated and 12 mtDNA-encoded genes downregulated in RAS-STCs versus Normal-STCs. Functional analysis revealed that nDNA-encoded and mtDNA-encoded differentially-expressed genes were primarily implicated in mitochondrial respiration and ATP synthesis. Mitochondria from RAS-STCs were swollen and showed cristae remodeling and loss, and decreased ATP production. Immunoreactivity of the mitochondrial biogenesis marker peroxisome proliferator-activated receptor gamma coactivator (PGC)-1α and expression of the mitomiRs miR-15a, miR-181a, 196a, and miR-296-3p, which target several mtDNA-genes, were higher in RAS-STCs compared to Normal-STCs, suggesting a potential modulation of mitochondria-related gene expression. These results demonstrate that RAS induces an imbalance in mtDNA- and nDNA-mitochondrial gene expression, impairing mitochondrial structure and function in swine STCs. These observations support development of gene gain- and loss-of-function strategies to ameliorate mitochondrial damage and preserve the reparative potency of STCs in patients with renal ischemia.