Disease relevance of CPT2

• The infantile-type CPT2 deficiency (10 families reported) presents as severe attacks of hypoketotic hypoglycemia, occasionally associated with cardiac damage commonly responsible for sudden death before 1 year of age [1].
• The infantile-type CPT2 presents as severe attacks of hypoketotic hypoglycemia, occasionally associated with cardiac damage commonly responsible for sudden death before 1 year of age [2].
• It is known from studies in rats that chemical inhibition of both CPT1 isoforms results in hypertrophy of the cardiomyocytes, leading to an increase in heart-weight of up to 25% [3].
• We present biochemical and molecular evidence for vertical transmission of a variable myopathy caused by heterozygosity for a single mutation, R503C, in the CPT2 gene [4].
• Carnitine palmityltransferase II (CPT2) deficiency and migraine headache: two case reports [5].

Psychiatry related information on CPT2

• Our search of the English literature indicates this to be the first time that the emotional stress has been documented to precipitate the CPT II syndrome [6].
• The performances of 37 manic patients, 34 euthymic patients with bipolar disorder and 34 control subjects on eight scores from Conners' CPT II, reflecting three different dimensions of sustained attention were compared [7].

High impact information on CPT2

• Identification of a common mutation in the carnitine palmitoyltransferase II gene in familial recurrent myoglobinuria patients [8].
• Transfection experiments in COS cells demonstrate that the mutation drastically depresses the catalytic activity of CPT II [8].
• Consequences of CPT II deficiency studied in fibroblasts differed in both sets of patients [9].
• With 25% residual activity CPT II would become rate limiting in skeletal muscle but not in liver, heart, and fibroblasts [9].
• Infantile form of carnitine palmitoyltransferase II deficiency with hepatomuscular symptoms and sudden death. Physiopathological approach to carnitine palmitoyltransferase II deficiencies [9].

Chemical compound and disease context of CPT2

• Myoglobinuria and carnitine palmityltransferase (CPT) deficiency: studies with malonyl-CoA suggest absence of only CPT-II [10].
• AIMS: To characterize PPARalpha regulation in human dilated cardiomyopathy (DCM), we studied the expression of cardiac PPARalpha, cardiac carnitine palmitoyl-transferase I (CPT-1), a major PPARalpha target gene, and of the cardiac glucose transporter GLUT-4 in patients with DCM [11].
• A small number of symptomatic patients appear to have significant residual CPT II activity (42-60%) The synergistic interaction of partial deficiencies of CPT II, muscle adenosine monophosphate deaminase and possibly other enzymes of muscle energy metabolism in the aetiology of episodic myopathy deserves wider consideration [12].
• The objective was to verify whether variants in the gene encoding the carnitine palmitoyltransferase I (CPT1), a key enzyme in beta-oxidation of fatty acids, are associated with obesity phenotypes, alone or in interaction with fat intake [13].
• We describe here a CPT II deficiency associating hypoketotic hypoglycemia, high plasma creatine kinase level, heart beat disorders, and sudden death in a 3-mo-old boy [9].

Biological context of CPT2

• Two CPT2 mutations in three Japanese patients with carnitine palmitoyltransferase II deficiency: functional analysis and association with polymorphic haplotypes and two clinical phenotypes [14].
• Despite rigorous mutation analysis, six of 13 individuals identified with CPT2 mutations remained as heterozygotes [15].
• A single nucleotide polymorphism was also identified 11 bp distal to the CPT2 polyadenylation site that will be useful for linkage analysis [15].
• Prenatal diagnosis may be offered for pregnancies at a 1/4 risk of infantile/severe-type CPT2 deficiency [1].
• Compared to younger adults, there was a 50% downregulation of CPT1 in elderly persons and in MDS patients [16].

Anatomical context of CPT2

• This study reports the molecular heterogeneity of CPT2 mutations and their biochemical consequences among a series of 59 individuals who were suspected of having CPT II deficiency based on the decreased CPT activity observed in muscle or leukocytes samples, clinical findings, or referral for mutation analysis from other laboratories [15].
• Type 2 carnitine palmitoyl transferase (CPT2) is involved in the transfer of long-chain fatty acid into the mitochondria [17].
• We tested the hypothesis that pharmacological stimulation of peroxisome proliferator-activated receptors (PPAR) can stimulate FAO in CPT2-deficient muscle cells [17].
• However, when tested in CPT2-deficient myoblasts, only the delta-agonist was able to restore FAO, whereas the alpha-agonist had no effect [17].
• The CPT system is made up of two separate proteins located in the outer- (CPT1) and inner- (CPT2) mitochondrial membranes [1].

Associations of CPT2 with chemical compounds

• We also identified a novel polymorphism in the CPT2 gene, a phenylalanine (352)-to-cysteine substitution (F352C), which did not alter CPT II activity in transfected cells [14].
• Accordingly, we show that a 48-h treatment of CPT2-deficient myoblasts by bezafibrate restored FAO in patient cells [17].
• Treatment is based upon avoidance of fasting and/or exercise, a low-fat diet enriched with medium chain triglycerides and carnitine ("severe" CPT2 deficiency) [1].
• Malonyl-CoA-sensitive carnitine palmitoyltransferase (CPT1) was detected but malonyl-CoA-insensitive carnitine palmitoyltransferase (CPT2) appeared to be absent [18].
• The formation of acetylcarnitine directly correlates with the CPT-II activity [19].

Regulatory relationships of CPT2

• [35S]Methionine-labeled porcine heart citrate synthase (used here as a positive control) and rat liver carnitine palmitoyltransferase II (CPT II) were generated by in vitro transcription and translation of their cDNA constructs in appropriate Bluescript plasmids [20].

Other interactions of CPT2

• Only from two of these genes (CPT1B and CPT2) have full genomic structures been described [21].
• All enzymes were found to be expressed, with a very high activity of two enzymes involved in the metabolism of long-chain fatty acids (CPT2 and VLCAD), whereas the activity of medium-chain acyl-CoA dehydrogenase (MCAD) was found to be low, when compared to liver [22].
• Other malonyl-CoA non-inhibitable members of the family, CPT II and carnitine acetyltransferase, do not contain this domain [23].
• The mRNA levels of other genes such as CPT II, 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase, and fatty acid synthase (FAS) are increased by etomoxir alone [24].
• We describe renopathological findings in a patient with CPT II deficiency associated with rhabdomyolysis, which suggested the pathological role of myoglobin casts in the development of tubular necrosis [25].

Analytical, diagnostic and therapeutic context of CPT2

• Extensive sequence analysis was subsequently performed on 14 samples which either had a CPT2 mutation detected by ASO screening or the residual CPT activity was below that observed in ASO positive samples [15].
• Quantitative immunoblotting revealed the presence of a normal abundance of CPT2 protein in the patient's muscle [18].
• The catalytic activity of CPT2 was measured in muscle biopsies by the isotope exchange method and CPT2 immunoreactivity was quantitated by an enzyme-linked immunosorbent assay [26].
• We studied fuel utilization by indirect calorimetry and stable isotope methodology in four patients with CPT II deficiency, three subjects who carried one CPT2 gene mutation, and five healthy control subjects [27].
• We therefore performed a series of metabolic studies in a 43-yr-old woman homozygous for the Ser113Leu mutation in the CPT II gene, the single most common genetic cause of CPT II deficiency, and compared the results with data from a male and female control group taken from the Tübingen family study database [28].

References