Transcriptional effects of conditional parkin-overexpression in PC12-cells

Mutations in the parkin gene are the commonest cause of early-onset, recessive parkinsonism. The parkin protein functions as an E3-ubiquitin-protein ligase. This activity is thought to participate in the detoxification of specific substrate proteins and in intracellular signaling cascades. To further analyse the latter, we have established cell culture conditions using tet-off-PC12 cells, in which parkin can be switched on in the desired concentration. 12 and 36 hours after turning parkin expression on, RNA was extracted and analyzed by Affymetrix Chip technology. We could identify time-dependent expression changes of a number of genes, involved in several signal transduction pathways. In our quantitative PCR validation, we concentrated on apoptosis pathways and APP-processing and could confirm changes in genes like ADAM 10, a protease cleaving the amyloid precursor protein, and caspase 3, a downstream effector of apoptosis. These changes were especially seen at the 36h time point. We are currently evaluating these changes under Parkinson-related cell-stress conditions to better understand the cytoprotective properties of Parkin.