Regional and cellular expression of the parkin gene in the rat cerebral cortex

A mutation in the parkin gene has been identified as the cause for an autos omal recessively inherited form of early onset Parkinson's disease. We have recently isolated the mRNA coding for the rat homologue of parkin and show ed its widespread expression in the central nervous system (CNS) by in situ hybridization. In the present study we investigated the distribution of pa rkin in the rat cerebral cortex with a polyclonal antibody that reacts with a single similar to 52-kDa protein, corresponding to the predicted molecul ar mass of parkin. Conventional light microscopic studies revealed intense parkin immunoreactivity (IR) throughout the cortex. Examination of mixed co rtical neuro-glial cultures by indirect immunofluorescence technique couple d to traditional epifluorescence and confocal microscopy analysis demonstra ted the expression of parkin in the cytoplasm and neurites of neurons, and its absence in glial fibrillary acidic protein (GFAP)-positive astrocytes. The predominant neuronal parkin-IR and -mRNA expression was confirmed by We stern blot analysis and reverse transcription-polymerase chain reaction (RT -PCR), respectively, performed on highly enriched neuronal and type I astro cytes cultures. The information gathered in our study about the cellular an d subcellular distribution of parkin should facilitate further research on its physiological role in the nervous system.