Regulation and pathophysiological implications of UDP-GlcNAc 2-epimerase/ManNAc kinase (GNE) as the key enzyme of sialic acid biosynthesis.
The key enzyme for the biosynthesis of N-acetylneuraminic acid, from which all other sialic acids are formed, is the bifunctional enzyme UDP-N-acetylglucosamine 2-epimerase/N-acetylmannosamine kinase (GNE). GNE is a highly conserved protein found throughout the animal kingdom. Its highest expression is seen in the liver and placenta. GNE is regulated by a variety of biochemical means, including tetramerization promoted by the substrate UDP-GlcNAc, phosphorylation by protein kinase C and feedback inhibition by CMP-Neu5Ac, which is defect in the human disease sialuria. GNE knock-out in mice leads to embryonic lethality, emphasizing the crucial role of this key enzyme for sialic acid biosynthesis. The metabolic capacity to synthesize sialic acid and CMP-sialic acid upon ManNAc loads is amazingly high. An additional characteristic of GNE is its interaction with proteins involved in the regulation of development, which might play a crucial role in the hereditary inclusion body myopathy. Due to the importance of increased concentrations of tumor-surface sialic acid, first attempts to find inhibitors of GNE have been successful.
Reinke
Stefan O
SO
Beuth Hochschule für Technik Berlin, Fachbereich Life Sciences and Technology, Labor für Biochemie, D-13347 Berlin, Germany.
Lehmer
Gerhard
G
Hinderlich
Stephan
S
Reutter
Werner
W
D000818:Animals; D002238:Carbohydrate Epimerases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D004194:Disease; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D019158:N-Acetylneuraminic Acid / Q000096:biosynthesis*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
D004791:Enzyme Inhibitors; D017853:Phosphotransferases (Alcohol Group Acceptor); C018765:N-acylmannosamine kinase; D002238:Carbohydrate Epimerases; C100033:UDP acetylglucosamine-2-epimerase; D019158:N-Acetylneuraminic Acid