GATM alleviates sepsis-induced acute kidney injury via PDK4-mediated glycolytic reprogramming in renal tubular epithelial cells.

BACKGROUND

This study aimed to identify a key target gene in proximal tubule cells (PTCs) of sepsis-induced acute kidney injury (S-AKI) and elucidate the underlying mechanisms.

METHODS

We screened and analyzed GEO datasets and identified a key gene, GATM, in S-AKI. An S-AKI mouse model was established via intraperitoneal injection of lipopolysaccharide (LPS), and HK-2 cells were used for in vitro experiments. The role of GATM was evaluated using adeno-associated virus (AAV)-mediated overexpression in mice and plasmid-mediated overexpression in HK-2 cells. To identify the downstream target genes of GATM, transcriptome sequencing was conducted. Pathological evaluation was performed using hematoxylin-eosin (HE) and periodic acid-Schiff (PAS) staining. Protein levels were determined by Western blotting (WB), immunohistochemistry (IHC), and immunofluorescence (IF) assays; Apoptosis was evaluated by TUNEL staining; Mitochondrial morphology and function were assessed by transmission electron microscopy (TEM), JC-1 and MitoSOX assays. Lactate concentration and cellular ATP levels were measured.

RESULTS

Through analysis of four datasets (GSE151658, GSE247727, GSE220812, and GSE139061), GATM was identified as a key gene in PTCs during S-AKI. GATM expression was downregulated in both S-AKI mice and LPS-stimulated HK-2 cells. In vivo, GATM overexpression improved renal function, alleviated tubular damage, decreased the expression of KIM-1, IL-6, Caspase-3, and 4-HNE, and reduced mitochondrial injury. In vitro, HK-2 cell viability was enhanced, TUNEL-positive cells were reduced, and damaged mitochondria were decreased. Transcriptome sequencing revealed that the PDK4-mediated glycolysis pathway was a downstream target of GATM. GATM overexpression downregulated PDK4 expression, reduced glycolytic enzyme levels (p-PDHA, HK2, LDHA, GLUT1) and lactate, and increased ATP production. However, PDK4 overexpression in HK-2 cells abolished the protective effects of GATM, enhanced glycolysis, increased lactate levels, and reduced ATP production.

CONCLUSION

GATM plays a protective role in S-AKI by inhibiting PDK4-mediated aerobic glycolysis, enhancing ATP production, and restoring energy metabolism and mitochondrial function in PTCs.