Protein phosphatase type 2Calpha and 2Cbeta are involved in fatty acid-induced apoptosis of neuronal and endothelial cells.

Unsaturated fatty acids with special structural features have been shown to activate serine/threonine protein phosphatase type 2C (PP2C) isoforms alpha and beta at physiological Mg(2+)-concentrations in vitro. These compounds also induce apoptosis in neuronal and endothelial cells. In this study we further analysed this striking correlation and tried to elucidate whether or not there is a causative relationship between activation of PP2C and induction of apoptosis. We employed RNA interference to simultaneously knock down PP2Calpha and PP2Cbeta in SH-SY5Y cells or HUVECs, respectively. This downregulation was transient. Treatment of SH-SY5Y cells or HUVECs with oleic acid (18:1,cis-Delta(9)) caused apoptosis in a time- and concentration-dependent manner. In both cases, cells with reduced PP2C-levels were less susceptible to oleic acid-induced cell damage. In conclusion, our results demonstrate that PP2C activation by unsaturated fatty acids actually causes apoptosis in neuronal and endothelial cells.