Oligodendrocyte development and myelinogenesis are not impaired by high concentrations of phenylalanine or its metabolites.
Phenylketonuria (PKU) is a metabolic genetic disease characterized by deficient phenylalanine hydroxylase (PAH) enzymatic activity. Brain hypomyelination has been reported in untreated patients, but its mechanism remains unclear. We therefore investigated the influence of phenylalanine (Phe), phenylpyruvate (PP), and phenylacetate (PA) on oligodendrocytes. We first showed in a mouse model of PKU that the number of oligodendrocytes is not different in corpus callosum sections from adult mutants or from control brains. Then, using enriched oligodendroglial cultures, we detected no cytotoxic effect of high concentrations of Phe, PP, or PA. Finally, we analyzed the impact of Phe, PP, and PA on the myelination process in myelinating cocultures using both an in vitro index of myelination, based on activation of the myelin basic protein (MBP) promoter, and the direct quantification of myelin sheaths by both optical measurement and a bioinformatics method. None of these parameters was affected by the increased levels of Phe or its derivatives. Taken together, our data demonstrate that high levels of Phe, such as in PKU, are unlikely to directly induce brain hypomyelination, suggesting involvement of alternative mechanisms in this myelination defect.
Schoemans
Renaud
R
Human Genetics, GIGA-Research, University of Liège, Liège, Belgium.
Aigrot
Marie-Stéphane
MS
Wu
Chaohong
C
Marée
Raphaël
R
Hong
Pengyu
P
Belachew
Shibeshi
S
Josse
Claire
C
Lubetzki
Catherine
C
Bours
Vincent
V
D000818:Animals; D002478:Cells, Cultured; D003337:Corpus Callosum / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D007763:Lac Operon; D051379:Mice; D008817:Mice, Mutant Strains; D008822:Mice, Transgenic; D004676:Myelin Basic Protein / Q000235:genetics / Q000378:metabolism; D009186:Myelin Sheath / Q000378:metabolism / Q000473:pathology*; D009836:Oligodendroglia / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D010649:Phenylalanine / Q000378:metabolism / Q000494:pharmacology*; D010651:Phenylalanine Hydroxylase / Q000235:genetics* / Q000378:metabolism; D010661:Phenylketonurias / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D011401:Promoter Regions, Genetic / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar
D004676:Myelin Basic Protein; D010649:Phenylalanine; D010651:Phenylalanine Hydroxylase