Longevity-associated mitochondrial DNA 5178 A/C polymorphism influences effects of cigarette smoking on serum protein fraction levels in Japanese men

Mitochondrial ND1 T4216C and ND2 C5178A mutations are associated with maternally transmitted diabetes mellitus

Mutations in mitochondrial DNA (mtDNA) are important causes for type 2 diabetes mellitus (T2DM). To investigate the association between mtDNA mutations/variants and diabetes, we reported here clinical, genetic and biochemical characterization of a Chinese pedigree with maternally transmitted T2DM. Using PCR and direct sequencing analysis of mitochondrial genomes from the matrilineal relatives, we identified two potential pathogenic mutations, m.T4216C (p.Y304H) and m.C5178A (p.L237M) in the ND1 and ND2 genes, respectively, together with a set of genetic polymorphisms belonging to the human mitochondrial haplogroup D4b. Moreover, by isolating and analyzing polymononuclear leukocytes generated from the T2DM patients and controls, we identified lower levels of mitochondrial membrane potential and ATP production in T2DM patients than in the controls, in contrast, a significantly higher level of reactive oxygen species was observed in the T2DM patients carrying both of the m.T4216C and m.C5178A mutations (p < 0.05 for all). In addition, the plasma levels of malondialdehyde and 8-hydroxydeoxyguanosine in the T2DM patients markedly increased, while the level of superoxide dismutase decreased (p < 0.05 for all). Taken together, our data indicated that the ND1 T4216C and ND2 C5178A mutations may lead to oxidative stress and impair the mitochondrial function, and this, in turn, might have been involved in the pathogenesis and progression of T2DM in this pedigree. Thus, our study provides novel insight into the pathophysiology of T2DM that is manifested by mitochondrial dysfunction.

NADH dehydrogenase subunit-2 237 Leu/Met polymorphism modulates the effects of coffee consumption on the risk of hypertension in middle-aged Japanese men

Background

Habitual coffee consumption has been reported to lower blood pressure in the Japanese population. The NADH dehydrogenase subunit-2 237 leucine/methionine (ND2-237 Leu/Met) polymorphism is associated with longevity and modifies the effects of alcohol consumption on blood pressure in the Japanese population. The objective of this study was to determine whether this polymorphism also modifies the effects of coffee consumption on blood pressure or the risk of hypertension in middle-aged Japanese men.

Methods

A total of 398 men (mean age ± standard deviation, 53.8 ± 7.8 years) were selected from among individuals visiting the hospital for regular medical check-ups. Hypertension was defined as a systolic blood pressure ≥140 mm Hg, diastolic blood pressure ≥90 mm Hg, or antihypertensive drug treatment. Polymerase chain reaction-restriction fragment length polymorphism using the restriction enzyme AluI was performed to determine ND2-237 Leu/Met genotype.

Results

In subjects with ND2-237Leu, coffee consumption was significantly and negatively associated with diastolic blood pressure (P = 0.007). The odds ratio (OR) for hypertension was significantly lower in subjects with ND2-237Leu who consumed 2 or 3 cups of coffee per day than in those who consumed less than 1 cup of coffee per day (OR, 0.517; 95% confidence interval [CI], 0.276 to 0.968; P = 0.039). After adjustment, the OR remained significant (OR = 0.399; 95% CI, 0.184 to 0.869; P = 0.020). Moreover, after adjustment, the OR was significantly lower in subjects with ND2-237Leu who consumed more than 4 cups of coffee per day than in those who consumed less than 1 cup of coffee per day (OR, 0.246; 95% CI, 0.062 to 0.975; P = 0.046). However, the association between ND2-237Met genotype and hypertension did not depend on coffee consumption.

Conclusions

The present results suggest that the ND2-237 Leu/Met polymorphism modulates the effects of coffee consumption on hypertension risk in middle-aged Japanese men.

Longevity-associated mitochondrial DNA 5178 C/A polymorphism and its interaction with cigarette consumption are associated with pulmonary function in middle-aged Japanese men

Pulmonary function is a crucial factor associated with longevity. Mitochondrial DNA 5178 cytosine/adenine (Mt5178 C/A) polymorphism is reported to be associated with longevity in the Japanese population. We have previously reported that Mt5178 C/A polymorphism is widely associated with physiological and biochemical status. The objective of this study was to investigate whether Mt5178 C/A polymorphism is associated with pulmonary function. The subjects were 463 Japanese men (mean age +/- SD 54.0 +/- 7.6 years). Genotyping of Mt5178 C/A was performed by polymerase chain reaction-restriction fragment length polymorphism. A cross-sectional study of the relationship between genotype and spirometric data, namely forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV(1)), was conducted. Among younger subjects (age <55 years), FVC and FEV(1) were significantly higher for men with Mt5178A than for those with Mt5178C. Interaction between Mt5178 C/A polymorphism and smoking habits in FEV(1)/FVC ratio was observed. Cigarette consumption (pack-years of smoking) was significantly and negatively associated with FEV(1)/FVC ratio for men with Mt5178C. Among older subjects (age >or=55 years), FEV(1)/FVC ratio was significantly lower for current smokers with Mt5178C than for never smokers with Mt5178C or for never smokers with Mt5178A. Mt5178 C/A polymorphism and its interaction with cigarette consumption may be associated with pulmonary function in Japanese men.

The association of mitochondrial DNA 5178 C > a polymorphism with plasma lipid levels among three ethnic groups

Mitochondria are eukaryotic cytoplasmic organelles responsible for oxidative phosphorylation. The C to A nucleotide transversion in the NADH dehydrogenase subunit 2 (MT-ND2) coding region of mitochondrial DNA has been reported to be associated with plasma lipid levels, adult onset diseases and longevity. We have examined the role of this polymorphism in relation to plasma lipid levels and age in a total of 713 healthy individuals belonging to 3 ethnic groups in Singapore. The frequency of the A allele was significantly higher (p < 0.05) among the Chinese (0.15) in comparison to the Malays (0.05) and Indians (0.02). No significant difference in the frequency of the allele was observed between healthy and coronary artery disease subjects, and between age-stratified subjects. We found that the polymorphism is significantly associated in an ethnic- and gender-specific manner with plasma apoB levels in the Chinese males (p < 0.05). This is the first epidemiological report of the mt5178 C > A polymorphism and its association with plasma lipid levels in Asian populations outside Japan.

Longevity-associated mitochondrial DNA 5178 C/A polymorphism is associated with fasting plasma glucose levels and glucose tolerance in Japanese men

Mitochondrial DNA 5178 cytosine/adenine (Mt5178 C/A) polymorphism is reportedly associated with longevity in the Japanese population, and the Mt5178A genotype may resist the onset of type 2 diabetes. To investigate whether Mt5178 C/A polymorphism is associated with glucose tolerance, we conducted a cross-sectional study using the 75-g oral glucose tolerance test (OGTT) in which non-diabetic Japanese male subjects were classified into three subgroups by body mass index (BMI): BMI<22 (n=91); 22< or =BMI<25 (n=138); and BMI> or =25 (n=67). The frequency of Mt5178A was significantly lower among 'BMI<22' subjects exhibiting impaired fasting glucose and impaired glucose tolerance than among those with normal glucose tolerance. In the 'BMI<22' group, fasting plasma glucose (FPG) levels and plasma glucose levels at 60 and 120 min after glucose load (OGTT-1h and OGTT-2h, respectively) were significantly lower in the Mt5178A genotype than in the Mt5178C genotype. After adjusting for age, BMI, habitual smoking, habitual drinking and family history of diabetes, FPG levels and OGTT-2h levels were still significantly lower in the Mt5178A genotype than in the Mt5178C genotype. However, after adjusting for covariates, in both the '22< or =BMI<25' and 'BMI> or =25' groups, FPG levels were significantly higher in the Mt5178A genotype than in the Mt5178C genotype. Differences in the effect of alcohol consumption on FPG levels and glucose tolerance between the Mt5178 C/A genotypes were observed. The present results suggest that Mt5178 C/A polymorphism may be associated with FPG levels and glucose tolerance in middle-aged Japanese men.

Genetic epidemiological studies of longevity-associated mitochondrial DNA 5178 C/A polymorphism

Mitochondrial DNA 5178 cytosine/adenine (Mt5178 C/A) polymorphism is associated with longevity in the Japanese population, and the Mt5178A genotype may confer antiatherogenic advantages. Individuals with the Mt5178A genotype may be more resistant to adult-onset diseases, such as myocardial infarction, cerebrovascular diseases and type 2 diabetes, than those with the Mt5178C genotype. Moreover, Mt5178 C/A polymorphism has been reported to be associated with blood pressure, serum lipid levels, hematological parameters, intraocular pressure, serum protein fraction levels and serum electrolyte levels in healthy Japanese individuals. Differences in the influence of habitual drinking or habitual smoking on health status between the Mt5178C genotype and the Mt5178A genotype have been reported. The individual modification of drinking habits or smoking habits based on the genotyping of Mt5178 C/A may promote improved health and lead to the establishment of personalized prevention strategies for adult-onset diseases.

Interaction between longevity-associated mitochondrial DNA 5178 C/A polymorphism and cigarette smoking on hematological parameters in Japanese men

Mitochondrial DNA 5178 C/A (mt5178 C/A), namely NADH dehydrogenase subunit 2 237 Leu/Met, polymorphism is as reported in literature associated with longevity and susceptibility to ischemic heart disease or cerebrovascular disorders in the Japanese population. Previous reports suggested that mt5178A genotype exerts antiatherogenic effects. The aim of this study was to investigate whether mt5178 C/A polymorphism is associated with hematological parameters, such as thrombogenic risk factors for myocardial infarction and stroke, in 321 healthy Japanese men. No significant differences were observed between mt5178 C/A genotypes, but in subjects with body mass index (BMI) of < or = 23, this polymorphism influenced the effects of habitual smoking on hematological parameters. Red blood cell (RBC) counts were significantly lower and mean corpuscular hemoglobin (MCH) levels were significantly higher in smokers with mt5178A than nonsmokers with mt5178A. Platelet counts were significantly higher in smokers with mt5178C than nonsmokers with mt5178C. Cigarette consumption was strongly associated with RBC counts, mean corpuscular volume levels, and MCH levels for men with mt5178A, and was associated with platelet counts for those with mt5178C. Moreover, BMI was significantly positively associated with RBC counts and platelet counts only in men with mt5178A, age was significantly negatively associated with RBC counts only in men with mt5178C. These data suggest that mt5178 C/A polymorphism may influence the effects of cigarette smoking on hematological parameters in healthy BMI < or = 23 Japanese men.

Longevity-associated NADH dehydrogenase subunit-2 polymorphism and serum electrolyte levels in middle-aged obese Japanese men

Mitochondrial DNA 5178 cytosine/adenine polymorphism, which is also called NADH dehydrogenase subunit-2 237 leucine/methionine (ND2-237 Leu/Met) polymorphism is associated with Japanese longevity. This polymorphism is widely associated with blood pressure, serum lipid levels, hematological parameters, intraocular pressure, and serum protein fraction levels. However, there have been no reports on the association between ND2-237 Leu/Met polymorphism and serum electrolyte levels. To investigate this relationship, we performed an association study in 321 healthy middle-aged Japanese men. Crude data showed that serum sodium levels and serum chloride levels were significantly lower in men with ND2-237 Met than in those with ND2-237 Leu (P = 0.021 and 0.003, respectively). Cigarette consumption and body mass index were significantly and positively associated with serum chloride levels (P = 0.002 and 0.008, respectively) and hemoglobin levels were significantly and negatively associated with them (P = 0.007) in ND2-237 Leu genotypic men. In men with ND2-237 Met, only hemoglobin levels were significantly and negatively associated with serum chloride levels (P = 0.025). After adjusting for covariates, only in male obese (body mass index> or =25) subjects, serum sodium and chloride levels remained significantly lower, and serum calcium levels appeared to be significantly higher in ND2-237 Met than in ND2-237 Leu (P = 0.013, <0.001, and 0.046, respectively). Longevity-associated NADH dehydrogenase subunit-2 polymorphism may influence serum electrolyte levels in middle-aged obese Japanese men.

Longevity-associated mitochondrial DNA 5178 A/C polymorphism is associated with intraocular pressure in Japanese men

BACKGROUND

Mitochondrial DNA 5178 adenine/cytosine (mt5178 A/C) polymorphism has been reported to be associated with longevity in Japanese individuals, with experimental findings concluding that mt5178 A is an anti-atherogenic genotype. The aim of this study was to determine whether mt5178 A/C polymorphism influences intraocular pressure (IOP), and its relationship with the development of arteriosclerosis.

METHODS

Four hundred and forty-nine male volunteers who had visited a general hospital for medical check-up between August 1999 and August 2000 were enrolled. Of these, 386 Japanese men who had not undergone any medical treatment for hypertension, ocular hypertension or glaucoma were selected as subjects of this study. After these subjects were genotyped, a cross-sectional study regarding the relationship between genotype and IOP was conducted.

RESULTS

Mean IOP was significantly higher in men with mt5178 C (13.3 mmHg) than in those with mt5178 A (12.7 mmHg) (P = 0.037). This significant difference in mean IOP between the two genotypes remained evident after adjusting for age, body mass index, blood pressure, habitual smoking and habitual drinking. Interactions between mt5178 A/C polymorphism and habitual smoking or daily alcohol consumption with regard to IOP were observed. According to multiple regression analysis, habitual smoking was significantly associated with IOP in men with mt5178 A (P for trend = 0.020), while daily alcohol consumption was significantly associated with IOP in those with mt5178 C (P for trend = 0.021).

CONCLUSION

Longevity-associated mitochondrial DNA 5178 A/C polymorphism may be associated with IOP in Japanese men.

Longevity-associated mitochondrial DNA 5178 A/C polymorphism modulates effects of daily drinking and cigarette consumption on serum triglyceride levels in middle-aged Japanese men

Mitochondrial DNA 5178 adenine/cytosine (mt5178 A/C) polymorphism is one of the longevity-associated mitochondrial DNA polymorphisms. The frequency of the mt5178A genotype is significantly higher in Japanese centenarians than in the general population. We previously reported that serum high-density lipoprotein cholesterol levels were significantly higher in men with mt5178A than in those with mt5178C. However, this significant difference disappeared after adjusting for drinking frequency. To investigate the interaction between mt5178 A/C polymorphism and habitual drinking on serum lipid levels, we performed an association study in 321 healthy middle-aged Japanese men. Interaction between mt5178 A/C polymorphism and daily drinking on serum triglyceride (TG) levels was observed (P=0.019). Moreover, interaction between mt5178 A/C polymorphism and cigarette consumption on serum TG levels was also observed (P=0.022). Multiple regression analysis showed that, in men with mt5178A, daily drinking decreased TG levels (P=0.025), and cigarette consumption increased TG levels (P<0.001), while in men with mt5178C, the effects of daily drinking and cigarette consumption on TG levels were unclear. No interaction was observed on other lipid levels. Longevity-associated mitochondrial DNA 5178 A/C polymorphism thus influences the effects of daily drinking and cigarette consumption on TG levels in middle-aged Japanese men.

Mitochondrial genome single nucleotide polymorphisms and their phenotypes in the Japanese

Polymorphisms in the human mitochondrial genome have been used for the elucidation of phylogenetic relationships among various ethnic groups. Because analysis by mitochondrial genetics has detected pathogenic mutations causing mitochondrial encephalomyopathy or cardiomyopathy, most of the mitochondrial single nucleotide polymorphisms (mtSNPs) found in control subjects have been regarded as merely normal variants. However, we cannot exclude the possibility that the mitochondrial functional differences among individuals are ascribable at least in part to the mtSNPs of each individual. Human lifespan in ancient history was much shorter than that at the present time. Therefore, it is reasonable to speculate that certain mtSNPs that predispose one toward susceptibility to adult- or elderly-onset diseases, such as Parkinson's disease and Alzheimer's disease, have never been a target for natural selection in the past. Similarly, thrifty mtSNPs that had been advantageous for survival under severe famine or cold climate conditions might turn out to be related to satiation-related diseases, such as diabetes mellitus and obesity. To examine these hypotheses, we have constructed a mtSNP database by sequencing the entire mitochondrial genomes of 672 subjects: 96 in each of seven groups (i.e., centenarians, young obese or non-obese subjects, diabetic patients with or without major vascular involvement, patients with Parkinson's disease, and those with Alzheimer's disease).