CRAT
Carnitine O-acetyltransferase (EC 2.3.1.137) (EC 2.3.1.7) (Carnitine acetylase) (Carnitine acetyltransferase) (CAT) (CrAT) [CAT1]
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Lung function is a strong predictor of mortality. While inflammatory markers have been associated with lung function decrease, pathways are still poorly understood and epigenetic changes may participate in lung function decline mechanisms. We studied the cross-sectional association between DNA methylation in nine inflammatory genes and lung function in a cohort of 756 elderly men living in the metropolitan area of Boston. Participants donated a blood sample for DNA methylation analysis and underwent spirometry at each visit every 3 to 5 y from 1999-2006. We used separate multivariate mixed effects regression models to study the association between each lung function measurement and DNA methylation within each gene. Decreased CRAT, F3 and TLR2 methylation was significantly associated with lower lung function. One interquartile range (IQR) decrease in DNA methylation was associated with lower forced vital capacity (FVC) and forced expiratory volume in one second (FEV 1), respectively by 2.94% (p < 10 (-4)) and 2.47% (p < 10 (-3)) for F3, and by 2.10% (p < 10 (-2)) and 2.42% (p < 10 (-3)) for TLR2. Decreased IFNγ and IL6 methylation was significantly associated with better lung function. One IQR decrease in DNA methylation was associated with higher FEV 1 by 1.75% (p = 0.02) and 1.67% (p = 0.05) for IFNγ and IL6, respectively. These data demonstrate that DNA methylation may be part of the biological processes underlying the lung function decline and that IFNγ and IL6 may have ambivalent roles through activation of negative feedback.
MeSH Terms
- Aged
- Aged, 80 and over
- Aging
- Cross-Sectional Studies
- DNA Methylation
- Epigenesis, Genetic
- Humans
- Inflammation
- Lung
- Male
- Oxidative Stress
- Promoter Regions, Genetic
- Regression Analysis
- Spirometry
DNA methylation has been associated with age-related disease. Intra-individual changes in gene-specific DNA methylation over time in a community-based cohort has not been well described. We estimated the change in DNA methylation due to aging for nine genes in an elderly, community-dwelling cohort of men. Seven hundred and eighty four men from the Veterans Administration Normative Aging Study who were living in metropolitan Boston from 1999-2009 donated a blood sample for DNA methylation analysis at clinical examinations repeated at approximately 3-5 year intervals. We used mixed effects regression models. Aging was significantly associated with decreased methylation of GCR, iNOS and TLR2 and with increased methylation of IFNγ, F3, CRAT and OGG. Obstructive pulmonary disease at baseline modified the effect of aging on methylation of IFNγ (interaction p = 0.04). For participants who had obstructive pulmonary disease at their baseline visit, the rate of change of methylation of IFNγ was -0.05% 5-methyl-cytosine (5-mC) per year (95% CI: -0.22, 0.13), but was 0.14% 5-mC per year (95% CI: 0.05, 0.24) for those without this condition. Models with random slopes indicated significant heterogeneity in the effect of aging on methylation of GCR, iNOS and OGG. These findings suggest that DNA methylation may reflect differential biological aging.
MeSH Terms
- Aged
- Aging
- Boston
- Cohort Studies
- DNA Methylation
- Epigenesis, Genetic
- Humans
- Longitudinal Studies
- Male
- United States
- United States Department of Veterans Affairs
Changes in key enzymes of oxidative metabolism at the mitochondrial level are known to be associated with the aging process, apoptosis, and many diseases. Considering the risk of acquiring a myelodysplastic syndrome (MDS) with age, the aim of this study was to quantify mRNA synthesis of the carnitine palmitoyltransferases (CPT1 and CPT2), carnitine acetyltransferase (CRAT), human specific microsomal CPT, and OCTN2 (organic cation transporter) in mononuclear cells of healthy humans of different age groups and MDS patients. Using quantitative reverse transcriptase real-time PCR we compared mRNA synthesis of the above mentioned enzymes in mononuclear cells from peripheral blood of 23 healthy persons (mean age 45 years), 9 blood and 22 bone marrow samples of 31 MDS patients with varying proportions of apoptotic cells (mean age 78 years), and blood samples of 30 age-matched controls. In addition, plasma carnitine levels were determined. Compared to younger adults, there was a 50% downregulation of CPT1 in elderly persons and in MDS patients. Reduction in CRAT, CPT 2, and OCTN2 was more than 85%. Reduction in microsomal CPT was more pronounced in MDS patients than in age-matched controls (96% vs. 43%). In MDS bone marrow cells there was a negative correlation of CPT1 and CRAT with the relative proportion of apoptotic cells. Plasma carnitine values were similar in all groups. The described reduction in transcription of different genes in blood cells which is well known in different tissues may reflect a systemic signaling process, associated with aging, apoptosis, and MDS.
MeSH Terms
- Adult
- Aged
- Aging
- Apoptosis
- Bone Marrow Cells
- Carnitine
- Carnitine Acyltransferases
- Carnitine O-Palmitoyltransferase
- Carrier Proteins
- Down-Regulation
- Female
- Humans
- Leukocytes, Mononuclear
- Male
- Membrane Proteins
- Middle Aged
- Myelodysplastic Syndromes
- Organic Cation Transport Proteins
- RNA, Messenger
- Reverse Transcriptase Polymerase Chain Reaction
- Solute Carrier Family 22 Member 5
- Transcription, Genetic
Aging affects oxidative metabolism in liver and other tissues. Carnitine acyltransferases are key enzymes of this process in mitochondria. As previously shown, the rate of transcription and activity of carnitine palmitoyltransferase CPT1 are also related to carnitine levels. In this study we compared the effect of dietary l-carnitine (100 mg l-carnitine/kg body weight/day over 3 months) on liver enzymes of aged rats (months 21-24) to adult animals (months 6-9) and age-related controls for both groups. The transcription rate of CPT1, CPT2, and carnitine acetyltransferase (CRAT) was determined by quantitative reverse transcription real-time PCR (RTQPCR) and compared to the activity of the CPT1A enzyme. The results showed that the transcription rates of CPT1, CPT2, and CRAT were similar in aged and adult control animals. Carnitine-fed old rats had a significant (p<0.05) 8-12-fold higher mean transcription rate of CPT1 and CRAT compared to aged controls, adult carnitine-fed animals, and adult controls, whereas the transcription rate of CPT2 was stimulated 2-3-fold in carnitine-fed animals of both age groups. With regard to the enzymatic activity of CPT1 there was a 1.5-fold increase in the old carnitine group compared to all other groups. RNA in situ hybridization also indicated an enhanced expression of CPT1A in hepatocytes from l-carnitine-supplemented animals. These results suggest that l-carnitine stimulates transcription of CPT1, CPT2, and CRAT as well as the enzyme activity of CPT1 in the livers of aged rats.
MeSH Terms
- Aging
- Animals
- Carnitine
- Carnitine O-Acetyltransferase
- Carnitine O-Palmitoyltransferase
- Dietary Supplements
- Enzyme Activation
- In Situ Hybridization, Fluorescence
- Liver
- Male
- Rats
- Rats, Sprague-Dawley
- Reverse Transcriptase Polymerase Chain Reaction
- Transcription, Genetic