Regulation von alpha-Synuklein - Relevanz für das sporadische Parkinson Syndrom
Zusammenfassung der Projektergebnisse
Parkinson’s disease (PD) is a late-onset neurodegenerative disease characterized by a massive loss of midbrain dopaminergic neurons (mDA) in the substantia nigra (SN) and subsequent dopamine depletion in the striatum. Recent data from our laboratory had demonstrated a progressive midbrain dopaminergic (mDA) neuron loss in mice with only one allele of the engrailed 1 gene (En1 +/-/ En2+/+). In this mutant, as observed in Parkinson’s disease (PD), the loss of mDA neurons is gradual and more pronounced in the SN than in the ventral tegmental area (VTA). The ability of homeoproteins to gain access to the cell interior (a process termed ‘transduction’) permitted to block this neuronal death by infusion of recombinant En2 (that can complement for En1) into the midbrain of these mice. In this present project, we wanted to examine if engrailed would be protective in an animal model of PD. One of the most frequently used models is the toxin-based MPTP/MPP+ model. Experiments performed in collaboration with Andreas Hartmann and Daniel Alvarez Fischer (INSERM U 679) indeed suggest that En is a protective factor for mDA neurons since it significantly protects against MPTP/MPP+ in vitro and in vivo (increase in mDA cell survival of ≈60%). We now are underway to identify the mechanisms underlying the En1/2- mediated protection. Using microarray analysis, metabolic labelling with subsequent mass spectrometry, cell culture based in vitro assays after the addition of exogenous En1 (+/- siRNA of selected candidates) and histochemical analyses after in vivo injection of En1 into En1 +/-/ En2+/+ mice, we are about to validate putative protection-relevant transcriptional and translational En1/2 targets expressed in mDA cells and to study their physiological functions. This will hopefully help to elucidate protection-relevant targets of En and understand the role of En in adult mDA neuron physiology and in Parkinson’s disease.
