AGAT, GAMT and SLC6A8 distribution in the central nervous system, in relation to creatine deficiency syndromes: a review
| Autor: | Braissant, O., Henry, H. |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2008 |
| Předmět: |
Amidinotransferases/deficiency
Amidinotransferases/genetics Amino Acid Metabolism Inborn Errors/enzymology Amino Acid Metabolism Inborn Errors/genetics Animals Brain/enzymology Creatine/deficiency Developmental Disabilities/enzymology Developmental Disabilities/genetics Genetic Predisposition to Disease Glycine/analogs & derivatives Glycine/metabolism Guanidinoacetate N-Methyltransferase/deficiency Guanidinoacetate N-Methyltransferase/genetics Humans Intellectual Disability/enzymology Intellectual Disability/genetics Language Development Disorders/enzymology Language Development Disorders/genetics Membrane Transport Proteins/deficiency Membrane Transport Proteins/genetics Movement Disorders/congenital Movement Disorders/enzymology Phenotype Prognosis Speech Disorders/enzymology Speech Disorders/genetics |
| Zdroj: | Journal of Inherited Metabolic Disease, vol. 31, no. 2, pp. 230-239 |
| Popis: | Creatine deficiency syndromes, either due to AGAT, GAMT or SLC6A8 deficiencies, lead to a complete absence, or a very strong decrease, of creatine within the brain, as measured by magnetic resonance spectroscopy. While the mammalian central nervous system (CNS) expresses AGAT, GAMT and SLC6A8, the lack of SLC6A8 in astrocytes around the blood-brain barrier limits the brain capacity to import creatine from the periphery, and suggests that the CNS has to rely mainly on endogenous creatine synthesis through AGAT and GAMT expression. This seems contradictory with SLC6A8 deficiency, which, despite AGAT and GAMT expression, also leads to creatine deficiency in the CNS. We present novel data showing that in cortical grey matter, AGAT and GAMT are expressed in a dissociated way: e.g. only a few cells co-express both genes. This suggests that to allow synthesis of creatine within the CNS, at least for a significant part of it, guanidinoacetate must be transported from AGAT- to GAMT-expressing cells, possibly through SLC6A8. This would explain the creatine deficiency observed in SLC6A8-deficient patients. By bringing together creatine deficiency syndromes, AGAT, GAMT and SLC6A8 distribution in CNS, as well as a synthetic view on creatine and guanidinoacetate levels in the brain, this review presents a comprehensive framework, including new hypotheses, on brain creatine metabolism and transport, both in normal conditions and in case of creatine deficiency. |
| Databáze: | OpenAIRE |
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