Alteration of p‐PKM2 by UV radiation and H2O2 in Human Keratinocytes

Abstract

UV radiation and oxidative stress have been shown to be related to skin aging and skin cancer. Our previous studies have demonstrated that UV radiation induces generation of reactive oxygen species that leads to MAP kinase activation and MMP expression with a result of collagen reduction in cultured human skin keratinocytes in vitro and in human skin in vivo. We have also found that UV radiation and oxidative stress induces dehydration in human skin cells. Existing data have indicated that oxidative stress may alter cellular metabolism. We hypothesized that UV radiation and oxidative stress may also change metabolism in skin cells. Here we examined the effects of UV radiation and hydrogen peroxide on the metabolism of cultured human skin keratinocytes (HaCat cells). Western blot analysis showed that UV radiation inactivates PKM2 in keratinocytes in a time dependent manner. Seahorse data showed that UV radiation and H2O2 treatments decrease oxygen consumption rate (OCR) in HaCat cells. mTOR inhibitor Rapamycin increases oxygen consumption in both untreated and H2O2 treated cells. However, ERK inhibitor U0126 increases OCR in untreated cells, but decreases in H2O2‐treated cells. PKM2 activator DASA increases OCR in untreated cells but decreases OCR in H2O2 treated cells. Given that H2O2 is a recognized inhibitor of PKM2, we conclude that inhibition of PKM2 by UV radiation and oxidative stress may directly affect oxygen consumption and glycolysis in human skin cells.​