PCNA regulates metabolism by stabilizing ENO1 and 6PGD

The essential roles of PCNA as a scaffold protein in DNA replication and repair are well established, while its more recently discovered cytosolic roles are less explored. Alpha-enolase (ENO1) and 6-phosphogluconate dehydrogenase (6PGD), important proteins in glycolysis and the Pentose Phosphate Pathway (PPP), respectively, both contain PCNA interacting motifs. Here we show reduced binding to PCNA when the PCNA interacting motif APIM in ENO1 is mutated. Mutant cells have lower ENO1 protein levels, have reduced glucose consumption, altered glycolytic metabolite and nucleoside phosphate pools and increased activation of the citric acid cycle (TCA) compared to parental cells. Treatment of a panel of haematological cell lines with a cell penetrating peptide containing APIM (ATX-101), lead to a metabolic shift with reduction in glycolytic metabolite and nucleoside phosphate pools as well reduced levels of ENO1 and 6PGD proteins. These results suggests that PCNA stabilize ENO1 and 6PGD, and that targeting PCNA reduce the glycolysis, PPP and nucleoside phosphate pools via destabilization of these proteins.