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Tissue-specific strategies of the very-long chain acyl-CoA dehydrogenase-deficient (VLCAD-/-) mouse to compensate a defective fatty acid ?-oxidation.

ABSTRACT: Very long-chain acyl-CoA dehydrogenase (VLCAD)-deficiency is the most common long-chain fatty acid oxidation disorder presenting with heterogeneous phenotypes. Similar to many patients with VLCADD, VLCAD-deficient mice (VLCAD(-/-)) remain asymptomatic over a long period of time. In order to identify the involved compensatory mechanisms, wild-type and VLCAD(-/-) mice were fed one year either with a normal diet or with a diet in which medium-chain triglycerides (MCT) replaced long-chain triglycerides, as approved intervention in VLCADD. The expression of the mitochondrial long-chain acyl-CoA dehydrogenase (LCAD) and medium-chain acyl-CoA dehydrogenase (MCAD) was quantified at mRNA and protein level in heart, liver and skeletal muscle. The oxidation capacity of the different tissues was measured by LC-MS/MS using acyl-CoA substrates with a chain length of 8 to 20 carbons. Moreover, in white skeletal muscle the role of glycolysis and concomitant muscle fibre adaptation was investigated. In one year old VLCAD(-/-) mice MCAD and LCAD play an important role in order to compensate deficiency of VLCAD especially in the heart and in the liver. However, the white gastrocnemius muscle develops alternative compensatory mechanism based on a different substrate selection and increased glucose oxidation. Finally, the application of an MCT diet over one year has no effects on LCAD or MCAD expression. MCT results in the VLCAD(-/-) mice only in a very modest improvement of medium-chain acyl-CoA oxidation capacity restricted to cardiac tissue. In conclusion, VLCAD(-/-) mice develop tissue-specific strategies to compensate deficiency of VLCAD either by induction of other mitochondrial acyl-CoA dehydrogenases or by enhancement of glucose oxidation. In the muscle, there is evidence of a muscle fibre type adaptation with a predominance of glycolytic muscle fibres. Dietary modification as represented by an MCT-diet does not improve these strategies long-term.

SUBMITTER: Tucci S

PROVIDER: S-EPMC3443214 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature

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Tissue-specific strategies of the very-long chain acyl-CoA dehydrogenase-deficient (VLCAD-/-) mouse to compensate a defective fatty acid β-oxidation.

Tucci Sara S Herebian Diran D Sturm Marga M Seibt Annette A Spiekerkoetter Ute U

PloS one 20120914 9

Very long-chain acyl-CoA dehydrogenase (VLCAD)-deficiency is the most common long-chain fatty acid oxidation disorder presenting with heterogeneous phenotypes. Similar to many patients with VLCADD, VLCAD-deficient mice (VLCAD(-/-)) remain asymptomatic over a long period of time. In order to identify the involved compensatory mechanisms, wild-type and VLCAD(-/-) mice were fed one year either with a normal diet or with a diet in which medium-chain triglycerides (MCT) replaced long-chain triglyceri ...[more]

PMID: 23024820

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Project description:BackgroundVery-long-chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD) is diagnosed in the US through newborn screening (NBS). NBS often unequivocally identifies affected individuals, but a growing number of variant patterns can represent mild disease or heterozygous carriers.AimsTo evaluate the validity of standard diagnostic procedures for VLCADD by using functional in vitro tools.MethodsWe retrospectively investigated 13 patient samples referred to our laboratory because of a suspicion of VLCADD but with some uncertainty to the diagnosis. All 13 patients were suspected of having VLCADD either because of abnormal NBS or suggestive clinical findings. ACADVL genomic DNA sequencing data were available for twelve of them. Ten of the patients had an abnormal NBS suggestive of VLCADD, with three samples showing equivocal results. Three exhibited suggestive clinical findings and blood acylcarnitine profile (two of them had a normal NBS and the third one was unscreened). Assay of VLCAD activity and immunoblotting or immunohistologic staining for VLCAD were performed on fibroblasts. Prokaryotic mutagenesis and expression studies were performed for nine uncharacterized ACADVL missense mutations.ResultsVLCAD activity was abnormal in fibroblast cells from 9 patients (8 identified through abnormal NBS, 1 through clinical symptoms). For these 9 patients, immunoblotting/staining showed the variable presence of VLCAD; all but one had two mutated alleles. Two patients with equivocal NBS results (and a heterozygous genotype) and the two patients with normal NBS exhibited normal VLCAD activity and normal VLCAD protein on immunoblotting/staining thus ruling out VLCAD deficiency. Nine pathogenic missense mutations were characterized with prokaryotic expression studies and showed a decrease in enzyme activity and variable stability of VLCAD antigen.ConclusionsThese results emphasize the importance of functional investigation of abnormal NBS or clinical testing suggestive but not diagnostic of VLCADD. A larger prospective study is necessary to better define the clinical and metabolic ramifications of the defects identified in such patients.

Dataset Information

Tissue-specific strategies of the very-long chain acyl-CoA dehydrogenase-deficient (VLCAD-/-) mouse to compensate a defective fatty acid ?-oxidation.

Publications

Tissue-specific strategies of the very-long chain acyl-CoA dehydrogenase-deficient (VLCAD-/-) mouse to compensate a defective fatty acid β-oxidation.

Similar Datasets

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