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In an effort to gain deeper insight into the molecular processes underlying neurodegeneration in Parkinson's disease, we performed gene expression profiling at several early time points after MPTP-injection into old (1-year) mice. We used a PCR-based gene expression profiling method, digital expression pattern display (DEPD), a method of very high sensitivity and reproducibility, which displays almost all transcripts of a tissue. To identify cell death-associated genes, we defined clusters of differentially expressed transcripts with expression behaviour that correlated with the temporal profile of cell death progression and characterized one of these cell death clusters further. We selected one of the strongest regulated genes, the serum and glucocorticoid-regulated kinase 1 (sgk1), and validated its differential expression by Northern blot analysis, semiquantitative PCR andin situhybridization. Up-regulation ofsgk1(i) coincides with the onset of dopaminergic cell death in both the 8-week acute and 1-year subacute MPTP models, (ii) spans the entire brain, (iii) is attenuated by thel-deprenyl-mediated inhibition of the MPTP conversion to its active metabolite MPP+ and (iv) is not induced by dehydration. This study demonstrated that the combination of the DEPD technology, clustering analysis and a detailed histopathology is a useful tool for elucidating molecular pathways in neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Abstract Mutations in a protein designated Parkin were shown to be involved in the pathogenesis of autosomal recessive juvenile parkinsonism. Nothing is known about its regional and subcellular distribution in the mouse. In order to elucidate the Parkin mRNA and protein distribution in the adult mouse, the mouse cDNA was cloned and polyclonal antisera were generated against the N-terminal part of mouse Parkin. The antibodies were shown to be specific using Western blot analysis, immunostaining of cells transfected with mouse Parkin and pre-absorption tests. The Parkin protein expression profile was studied using immunohistochemistry and Western blot analysis and was compared with that of the mRNA yielded by in situ hybridization and RT-PCR analysis. Parkin protein was widely distributed in all subdivisions of the mouse brain. Low levels were found in the telencephalon and diencephalon, while the brainstem contained a large number of cells heavily expressing Parkin. Ultrastructural analysis and double immunohistochemistry revealed that the majority of Parkin-expressing cells were neurons, while only single glial cells exhibited immunostaining. The protein was distributed nonhomogeneously throughout the entire cytoplasm. A subpopulation of Parkin-immunopositive cells displayed speckled immunodeposits in the nucleus. Dopaminergic cells of the substantia nigra pars compacta exhibited high levels of Parkin mRNA but no Parkin protein, while the striatum contained immunopositive profiles but no mRNA signals. Our data indicate that Parkin is neither restricted to a single functional system nor associated with a particular transmitter system. The speckled nuclear distribution of Parkin immunoreactivity strongly suggests a role for Parkin in gene expression. [ABSTRACT FROM AUTHOR]