A rapid method for assay of branched-chain keto acid decarboxylation in cultured cells and its application to prenatal diagnosis of maple syrup urine disease

1978 ◽  
Vol 87 (1) ◽  
pp. 169-174 ◽  
Author(s):  
A.H. Fensom ◽  
P.F. Benson ◽  
Janet E. Baker
2000 ◽  
Vol 11 (5) ◽  
pp. 1919-1932 ◽  
Author(s):  
Philippe Jouvet ◽  
Pierre Rustin ◽  
Deanna L. Taylor ◽  
Jennifer M. Pocock ◽  
Ursula Felderhoff-Mueser ◽  
...  

Maple syrup urine disease (MSUD) is an inborn error of metabolism caused by a deficiency in branched chain α-keto acid dehydrogenase that can result in neurodegenerative sequelae in human infants. In the present study, increased concentrations of MSUD metabolites, in particular α-keto isocaproic acid, specifically induced apoptosis in glial and neuronal cells in culture. Apoptosis was associated with a reduction in cell respiration but without impairment of respiratory chain function, without early changes in mitochondrial membrane potential and without cytochrome c release into the cytosol. Significantly, α-keto isocaproic acid also triggered neuronal apoptosis in vivo after intracerebral injection into the developing rat brain. These findings suggest that MSUD neurodegeneration may result, at least in part, from an accumulation of branched chain amino acids and their α-keto acid derivatives that trigger apoptosis through a cytochrome c-independent pathway.


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