Resumen
The lipid peroxide scavenger enzyme glutathione peroxidase 4 (GPX4) and its cofactor glutathione play a crucial role in the recently described programmed cell death, ferroptosis. Since mitochondria are the major sources of reactive oxygen species in mammalian cells the linkage between mitochondria, mitochondrial ROS generation and ferroptosis emerged quite early. As a result of alternative splicing human GPX4 has three different isoforms: long form (lGPX4), short form (sGPX4) and nuclear form (nGPX4) of which sGPX4 was found essential. To clarify the potential role of mitochondria in ferroptosis the localization of both the long and short versions of GPX4 and the only verified glutathione transport protein SLC25A11 was investigated by different in silico tools. Targeting of lGPX4 and sGPX4 to multiple organelles is possible as a number of rule- and neural network-based algorithms showed concordant results to specific pathways. Hence the mitochondrial localization of both isoforms on the base of in silico prediction is possible. Since sGPX4 was found in multiple organelles and non-canonical import pathways are presumable we also evaluated the previously used in silico methods in predicting the localization of a chimeric signal containing peptide CYP2B1 as well as a solely mitochondrial targeted CYP27A1. Our in silico results showed that only the CELLO prediction tool ranked mitochondrial import with meaningful possibility based on neighboring sequence composition. Summarily the possible mitochondrial localization of both long and short isoforms of GPX4 and the glutathione transporter SLC25A11 support the assumption that mitochondria play an important role in the pathways leading to ferroptosis.