Proteomic analysis reveals KRIT1 as a modulator for the antioxidant effects of valproic acid in human bone-marrow mesenchymal stromal cells.

Valproic acid (VPA) protects human bone marrow-mesenchymal stromal cells (hBM-MSCs) against oxidative stress and improves their migratory ability through increasing the secretion of trophic factors. This suggests that VPA may be an excellent candidate for improving stem cell function. However, the molecular mechanisms of VPA in BM-MSCs are not known. In this study, we used a proteomic approach to investigate VPA-associated targets under oxidative stress conditions. Krev/Rap1 interaction Trapped-1 (KRIT1), a modulator for the homeostasis of intracellular reactive oxygen species (ROS), was identified as a target protein by two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) analyses. The up-regulation of KRIT1 and its target proteins (SOD2 and FoxO1) with VPA treatment of hBM-MSCs was revealed by qPCR and immunoblot analysis. Damage from oxidative stress was reduced in VPA-pretreated BM-MSCs, which was also confirmed by qPCR and immunoblot analysis. In addition, increased in intracellular ROS by H2O2 were also reduced by VPA pretreatment in BM-MSCs. This suggests that VPA reduces intracellular ROS level by the modulation of KRIT1 and its correlated proteins, FoxO1, SOD2, and cyclin D1. Thus, this study is the first to provide evidence that VPA modulates KRIT1 and intracellular ROS in BM-MSCs.