Very long-chain specific acyl-CoA dehydrogenase, mitochondrial (VLCAD) is an enzyme that in humans is encoded by the ACADVL gene. Mutations in the ACADVL are associated with very long-chain acyl-coenzyme A dehydrogenase deficiency. The protein encoded by this gene is targeted to the inner mitochondrial membrane, where it catalyzes the first step of the mitochondrial fatty acid beta-oxidation pathway. This acyl-Coenzyme A dehydrogenase is specific to long-chain and very-long-chain fatty acids. A deficiency in this gene product reduces myocardial fatty acid beta-oxidation and is associated with

cardiomyopathy Cardiomyopathy is a group of diseases that affect the heart muscle. Early on there may be few or no symptoms. As the disease worsens, shortness of breath, feeling tired, and swelling of the legs may occur, due to the onset of heart failure. A ...

. Alternative splicing results in multiple transcript variants encoding different isoforms.

Structure

The ACADVL gene contains 20

exons An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequence ...

, and is about 5.4 kb long. VLCAD has interesting gene structure in humans, in that is located in a head-to-head structure with the

DLG4 PSD-95 (postsynaptic density protein 95) also known as SAP-90 (synapse-associated protein 90) is a protein that in humans is encoded by the ''DLG4'' (discs large homolog 4) gene. PSD-95 is a member of the membrane-associated guanylate kinase (MAG ...

gene on Chromosome 17, and that the transcribed regions of these genes overlap. It has been shown that treatment with DEHP results in upregulation by the minimal promoter. While DLG4 and VLCAD share common regulatory elements, they each have separate and distinct tissue-specific elements that confer their function. In mice, these two genes are in a head-to-head orientation, but they do not overlap.

Function

The VLCAD enzyme catalyzes most of fatty acid beta-oxidation by forming a C2-C3 trans-double bond in the fatty acid. VLCAD is specific to very long-chain fatty acids, typically C16-acylCoA and longer. In mice that have VLCAD deficiency, there is little to no protein hyperacetylation in the liver; this implies that the VLCAD protein is also necessary for protein acetylation in this biological system.

Clinical significance

ACADVL is linked with very long-chain acyl-coenzyme A dehydrogenase deficiency (VLCADD), which has many symptoms, and typically presents as one of three phenotypes. The first is severe, with an early childhood onset and high mortality rate; the most common symptom is this form is

. The second is a late onset childhood form, with milder symptoms that present most commonly as hypoketotic hypoglycemia. The final form presents in adulthood, and presents as isolated skeletal muscle involvement,

rhabdomyolysis Rhabdomyolysis (also called rhabdo) is a condition in which damaged skeletal muscle breaks down rapidly. Symptoms may include muscle pains, weakness, vomiting, and confusion. There may be tea-colored urine or an irregular heartbeat. Some of th ...

, and myoglobinuria, which is triggered by exercise or fasting. The disease is typically diagnosed by first performing tandem mass spectrometry on a blood sample of the patient during a period of stress, and then performing molecular genetic testing for the presence of the ACADVL gene. The deficiency is treated systematically, but certain conditions such as fasting, myocardial irritation, dehydration, and high fat diets are avoided in attempt to prevent secondary complications.

Interactions

ACADVL has been shown to have 75 binary protein-protein interactions including 73 co-complex interactions. ACADVL appears to interact with RPSA and GPHN.

References

External links

GeneReviews/NCBI/NIH/UW entry on Very long-chain acyl-coenzyme A dehydrogenase deficiency
* {{DEFAULTSORT:Acadvl