Enhanced Expression of the Female-Biased Gene Gsta2 in Male Proximal Tubule Cells Improves Renal Resilience to Ischemia-Reperfusion Injury.

BACKGROUND Genetic sex is an important determinant of kidney injury and repair, with female kidneys typically exhibiting greater resilience to acute kidney injury (AKI). Among the sexually dimorphic genes in mouse proximal tubule cells, Gsta2, encoding an NRF2-regulated antioxidant enzyme, is strongly enriched in females. Here, we hypothesized that augmenting Gsta2 expression in male proximal tubule cells will enhance resistance to ischemia-reperfusion injury (IRI). METHODS To enable proximal tubule cell-specific expression of transgenes, we mapped and verified enhancer regions directing proximal tubule expression of human HNF4A. A synthetic HNF4A enhancer cassette driving Gsta2 was introduced into a safe harbor locus in transgenic mice thereby enhancing expression of Gsta2 in male mice. Following unilateral nephrectomy, transgenic and wild-type males were subjected to IRI. Post-IRI outcomes were assessed by examining kidney function, histological injury, and fibrotic progression for up to 28 days post-injury. RESULTS Enhancing Gsta2 expression in male proximal tubule cells lead to significantly higher glomerular filtration rates and attenuated fibrotic remodeling following IRI. Early-phase transcriptional analyses 4-hours post-injury showed reduced expression of immediate early genes (Jun, Fos, Egr1) suggesting a reduced stress response, diminished DNA double-strand DNA breaks (γH2AX incorporation into chomatin), and lower protein peroxidation. Later stage transgenic kidneys exhibited a reduction in fibrosis-associated transcripts (Acta2, Col1a1, Col3a1) and markers of failed proximal tubule cells repair (Havcr1, Vcam1, Ccl2). CONCLUSIONS Ectopic expression of Gsta2 in male proximal tubule cells reduced oxidative injury, injury associated fibrosis and maladaptive stress signaling following ischemia reperfusion injury.