PARP in glycolysis and mitochondrial respiration

Abstract

After renal injury, selective damage occurs in the proximal tubules as a result of inhibition of glycolysis; but the molecular mechanism is not known. Poly(ADP-ribose) polymerase (PARP) activation plays a critical role of proximal tubular cell death in several renal disorders. Here, we studied the role of PARP on glycolytic flux in pig kidney proximal tubule epithelial LLC-PK1 cells using XFp extracellular flux analyzer. Poly(ADP-ribosyl)ation by PARP activation was increased by 10 mM glucose in LLC-PK1 cells, but treatment with 3-aminobenzamide as a PARP inhibitor does-dependently prevented the PARP activation induced by glucose. Treatment with 1 mM 3-aminobenzamide significantly enhanced extracellular acidification rate increased by glucose, but not oligomycin; indicating that PARP inactivation increases only glycolytic activity during glycolytic flux including basal glycolysis, glycolytic activity, and glycolytic capacity in kidney proximal tubule epithelial cells. Glucose increased the activities of glycolytic enzymes including hexokinase, phosphoglucose isomerase, phosphofructokinase-1, glyceraldehyde-3-phosphate dehydrogenase, enolase, and pyruvate kinase in LLC-PK1 cells. Furthermore, PARP inactivation selectively augmented the activities of hexokinase, phosphofructokinase-1, and glyceraldehyde-3-phosphate dehydrogenase. In conclusion, these data suggest that PARP activation regulates glycolytic activity through poly(ADP-ribosyl)ation of hexokinase, phosphofructokinase-1, and glyceraldehyde-3-phosphate dehydrogenase in kidney proximal tubule epithelial cells.