Identification of fatty acid oxidation disorder patients with lowered acyl-CoA thioesterase activity in human skin fibroblasts.
BACKGROUND
Acyl-CoA thioesterases are enzymes that hydrolyze acyl-CoAs to the free fatty acid and coenzyme A (CoASH). These enzymes have been identified in several cellular compartments and are thought to regulate intracellular levels of acyl-CoAs, free fatty acids and CoASH. However, to date no patients deficient in acyl-CoA thioesterases have been identified.


METHODS
Acyl-CoA thioesterase activity was measured in human skin fibroblasts. Western-blot analysis was used to determine Type-II acyl-CoA thioesterase protein levels in patients.


RESULTS
Acyl-CoA thioesterase activity was found in human fibroblasts with all saturated acyl-CoAs from C4-CoA to C18-CoA, with highest activity detected with lauroyl-CoA and myristoyl-CoA (C12-CoA and C14-CoA). An antibody that recognizes the major isoforms of Type-II acyl-CoA thioesterases precipitated the majority of acyl-CoA thioesterase activity in fibroblasts, showing that the main thioesterase activity detected in fibroblasts is catalyzed by Type-II thioesterases. Measurement of acyl-CoA thioesterase activity from fibroblasts of 34 patients with putative fatty acid oxidation disorders resulted in the identification of three patients with lowered Type-II acyl-CoA thioesterase activity in fibroblasts. These patients also had lowered expression of Type-II acyl-CoA thioesterase protein in fibroblasts as judged by Western-blot analysis. However, mutation analysis failed to identify any mutation in the coding sequences for the mitochondrial acyl-CoA thioesterase II (MTE-II) or the cytosolic acyl-CoA thioesterase II (CTE-II).


CONCLUSIONS
We have described three patients with lowered Type-II acyl-CoA thioesterase protein and activity in human skin fibroblasts, which is the first description of patients with a putative defect in acyl-CoA thioesterases.
Hunt
M C
MC
Karolinska University Hospital at Huddinge, Stockholm, Sweden. mary.hunt@labmed.ki.se
Ruiter
J
J
Mooyer
P
P
van Roermond
C W T
CW
Ofman
R
R
Ijlst
L
L
Wanders
R J A
RJ
D015153:Blotting, Western / Q000379:methods; D016022:Case-Control Studies; D002675:Child, Preschool; D064429:Fatty Acid Synthases / Q000032:analysis / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D005347:Fibroblasts / Q000201:enzymology; D006801:Humans; D047468:Immunoprecipitation; D007231:Infant, Newborn; D008661:Metabolism, Inborn Errors / Q000201:enzymology*; D008928:Mitochondria / Q000201:enzymology; D010084:Oxidation-Reduction; D012867:Skin / Q000201:enzymology*; D013869:Thiolester Hydrolases / Q000032:analysis / Q000378:metabolism*
D005227:Fatty Acids; D064429:Fatty Acid Synthases; D013869:Thiolester Hydrolases; C022738:thioesterase II