Components of Energy Metabolism Expressed in Parkinson's Disease

Nicotinamide N-methyltransferase (NNMT) is an important enzyme that metabolizes xenobiotic compounds as part of a protective effect against toxins.Although not yet know why, in patients with Parkinson’s Disease there is an overexpression of NNMT, and studies have shown that an upregulation of NNMT is associated with an increase in Complex I activity and potentially, Complex IV and V. This ultimately leads to an increase in the production of ATP and an increase in reactive oxygen species, which then leads to the degeneration of dopaminergic neurons. In this study we have investigated the relationship between NNMT, Tyrosine Hydroxylase (TH) as well as Complex I, Complex IV and Complex V and their potential expression on the outer cell membrane using two approaches. The first approach was to localize protein expression in the human midbrain using immunofluorescence histochemistry with confocal microscopy analysis, looking at protein expression on the extracellular membrane by the omission of the detergent IGEPAL, which makes membranes permeable in tissue sections. With this approach we found that Complex I, IV and V staining in the absence of the detergent IGEPAL demonstrated punctate cellular staining similar to that observed in the presence of IGEPAL, which suggested that the fixation process for the tissues resulted in the permeabilization of cells and thus prevented the visualization of extracellular-only protein expression.The second approach investigated protein expression in the outer cell membrane using Western blotting, this analysis demonstrated the expression of Complex proteins in the outer membranes of cells.