AbstractsBiology & Animal Science

This work is divided in two parts. In the first, I investigated the effects of 2,3- dihydroxy-L-phenylalanine (L-DOPA) on the metabolism of human tyrosine hydroxylase (TH)-positive neuronal LUHMES cells. L-DOPA is the gold standard treatment for Parkinson’s disease (PD) and its effects on cellular metabolism are controversial. It induced a re-routing of intracellular carbon supplies. While glutamine contribution to tricarboxylic acid (TCA) cycle intermediates increased, glucose contribution to the same metabolites decreased. Carbon contribution from glucose was decreased in lactate and was compensated by an increased pyruvate contribution. Pyruvate reacted with hydrogen peroxide generated during the auto-oxidation of L-DOPA and lead to an increase of acetate in the medium. In the presence of L-DOPA, this acetate was taken up by the cells. In combination with an increased glutamate secretion, all these results seem to point towards a mitochondrial complex II inhibition. In the second part of this work, I studied and compared dopamine (DA)-producing in vitro systems. First, I compared gene and protein expression of catecholamine (CA)- related genes. Then, I performed molecular engineering to increase TH expression in LUHMES and SH-SY5Y cells. This was sufficient to induce DA production in SH-SY5Y, but not in LUHMES cells, indicating that TH expression is not sufficient to characterize dopaminergic neurons. Therefore I used SH-SY5Y cells overexpressing TH to study substrates for DA production. Upon overexpression of aromatic amino acid decarboxylase (AADC), LUHMES cells produced DA after L-DOPA supplementation. This model was useful to study L-DOPA uptake in LUHMES cells and I showed that L-DOPA is imported via large amino acid transporter (LAT). In conclusion, the expression of TH is not sufficient to obtain a DA-producing cell system and this work opened many and answered some questions about DA metabolism. Advisors/Committee Members: Aide à la Formation Recherche PhD (FNR) [sponsor], Hiller, Karsten [superviser], Haan, Serge [president of the jury], Leist, Marcel [member of the jury], Linster, Carole [member of the jury], Marcus, Katrin [member of the jury], Luxembourg Centre for Systems Biomedicine (LCSB): Metabolomics (Hiller Group) [research center].