Kumpei Tanisawa

Exome sequencing of senescence-accelerated mice (SAM) reveals deleterious mutations in degenerative disease-causing genes

BackgroundSenescence-accelerated mice (SAM) are a series of mouse strains originally derived from unexpected crosses between AKR/J and unknown mice, from which phenotypically distinct senescence-prone (SAMP) and -resistant (SAMR) inbred strains were subsequently established. Although SAMP strains have been widely used for aging research focusing on their short life spans and various age-related phenotypes, such as immune dysfunction, osteoporosis, and brain atrophy, the responsible gene mutations have not yet been fully elucidated.ResultsTo identify mutations specific to SAMP strains, we performed whole exome sequencing of 6 SAMP and 3 SAMR strains. This analysis revealed 32,019 to 38,925 single-nucleotide variants in the coding region of each SAM strain. We detected Ogg1 p.R304W and Mbd4 p.D129N deleterious mutations in all 6 of the SAMP strains but not in the SAMR or AKR/J strains. Moreover, we extracted 31 SAMP-specific novel deleterious mutations. In all SAMP strains except SAMP8, we detected a p.R473W missense mutation in the Ldb3 gene, which has been associated with myofibrillar myopathy. In 3 SAMP strains (SAMP3, SAMP10, and SAMP11), we identified a p.R167C missense mutation in the Prx gene, in which mutations causing hereditary motor and sensory neuropathy (Dejerine-Sottas syndrome) have been identified. In SAMP6 we detected a p.S540fs frame-shift mutation in the Il4ra gene, a mutation potentially causative of ulcerative colitis and osteoporosis.ConclusionsOur data indicate that different combinations of mutations in disease-causing genes may be responsible for the various phenotypes of SAMP strains.

Associations between the Serum 25(OH)D Concentration and Lipid Profiles in Japanese Men

AIM Low circulating 25-hydroxyvitamin D [25(OH)D] concentration has been linked to a high prevalence of cardiovascular disease. One explanation for this phenomenon is that there is an association between the serum 25(OH)D level and lipid profiles. However, studies examining this relationship are limited and have yielded inconsistent results. We thus aimed to evaluate the association between the serum 25(OH)D concentration and lipid profiles in Japanese men taking into consideration confounding factors, including the visceral fat area (VFA) and cardiorespiratory fitness. METHODS A total of 136 men (age range: 20-79 years) participated in our study. Fasting blood samples were analyzed to determine the 25(OH)D, oxidized low-density lipoprotein (oxLDL), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglyceride (TG), apolipoprotein (Apo)A-1 and ApoB levels. The VFA was evaluated on magnetic resonance imaging (MRI), and cardiorespiratory fitness was assessed by measuring the peak oxygen uptake (VO2 peak). RESULTS The median 25(OH)D concentration was 35.6 nmol/L, and the prevalence of 25(OH)D deficiency was 78.7%. A multiple linear regression analysis revealed that the serum 25(OH)D concentration was inversely related to the LDL-C/HDL-C, TG, ApoB and ApoB/ApoA-1 values, even after adjusting for age, season, smoking status, alcohol consumption, medication use, vitamin D intake, calcium intake, VFA and cardiorespiratory fitness. CONCLUSIONS Serum 25(OH)D level is inversely correlated with the LDL-C/HDL-C, TG, ApoB and ApoB/ApoA-1 values in Japanese men, independent of the VFA and cardiorespiratory fitness.

Vitamin D supplementation reduces insulin resistance in Japanese adults: a secondary analysis of a double-blind, randomized, placebo-controlled trial

Higher circulating 25-hydroxyvitamin D (25[OH]D) concentration has been linked to a lower prevalence of insulin resistance and type 2 diabetes mellitus. However, randomized controlled trials have not clarified the effect of vitamin D supplementation on insulin resistance in healthy adults. The objective of this study was to assess the effect of vitamin D supplementation for 1 year on insulin resistance; the study was a secondary analysis of a clinical trial. We hypothesized that increased 25(OH)D concentration after vitamin D supplementation for 1 year would significantly improve insulin resistance. Ninety-six healthy adults participated in this study, of whom 81 completed the study. The participants randomly received daily either 420 IU vitamin D3 or placebo in a double-blind manner for 1 year. The levels of fasting insulin, glucose, and other parameters were assessed at baseline and after 1 year of intervention. Homeostasis model assessment of insulin resistance index was calculated from insulin and glucose levels. Visceral fat area and physical activity were also investigated. Serum 25(OH)D and 1,25-dihydroxyvitamin D concentrations were significantly increased by approximately 29.5 nmol/L and 7.0 pg/mL, respectively, after 1-year vitamin D supplementation. After vitamin D supplementation, fasting glucose levels and values of homeostasis model assessment of insulin resistance index significantly decreased from 88.3 to 85.3 mg/dL (P < .01) and 1.17 to 0.84 (P < .01), respectively, and the results were independent of physical activity and visceral fat accumulation. In conclusion, the present study showed that vitamin D supplementation for 1 year effectively improves fasting glucose level and insulin resistance in healthy Japanese adults.

Acute endurance exercise lowers serum fibroblast growth factor 21 levels in Japanese men

The independent effects of acute endurance exercise on FGF21 metabolism are poorly understood. Therefore, the purpose of this study was to determine whether acute endurance exercise modulates serum postprandial FGF21 levels in an age‐dependent manner.

Polygenic risk for hypertriglyceridemia is attenuated in Japanese men with high fitness levels.

High cardiorespiratory fitness (CRF) is associated with a reduced risk for dyslipidemia; however, blood lipid levels are also affected by individual genetic variations. We performed a cross-sectional study to determine whether CRF modifies polygenic risk for dyslipidemia. Serum levels of triglycerides (TG), LDL cholesterol (LDL-C), and HDL cholesterol (HDL-C) were measured in 170 Japanese men (age 20-79 yr). CRF was assessed by measuring maximal oxygen uptake (Vo2max), and subjects were divided into low-fitness and high-fitness groups according to the reference Vo2max value for health promotion in Japan. We analyzed 19 single nucleotide polymorphisms (SNPs) associated with TG, LDL-C, or HDL-C levels. Based on these SNPs, we calculated three genetic risk scores (GRSs: TG-GRS, LDL-GRS, and HDL-GRS), and subjects were divided into low, middle, and high groups according to the tertile for each GRS. Serum TG levels of low-fitness individuals were higher in the high and middle TG-GRS groups than in the low TG-GRS group (P < 0.01 and P < 0.05, respectively), whereas no differences were detected in the TG levels of high-fitness individuals among the TG-GRS groups. In contrast, the high LDL-GRS group had higher LDL-C levels than did the low LDL-GRS group, and HDL-C levels were lower in the high HDL-GRS group than in the low HDL-GRS group regardless of the fitness level (P < 0.05). These results suggest that high CRF attenuates polygenic risk for hypertriglyceridemia; however, high CRF may not modify the polygenic risk associated with high LDL-C and low HDL-C levels in Japanese men.

Positive association between physical activity and PER3 expression in older adults

The circadian clock regulates many physiological functions including physical activity and feeding patterns. In addition, scheduled exercise and feeding themselves can affect the circadian clock. The purpose of the present study was to investigate the relationship between physical/feeding activity and expression of clock genes in hair follicle cells in older adults. Twenty adult men (age, 68 ± 7 years, mean ± SE) were examined in this cross-sectional study. Prior to hair follicle cell collection, the participants were asked to wear a uniaxial accelerometer for one week. The timings of breakfast, lunch, and dinner were also recorded. Hair follicle cells were then collected over a 24 h period at 4 h intervals. The amplitude of PER3 expression was positively correlated with moderate and vigorous physical activity (r = 0.582, p = 0.007) and peak oxygen uptake (r = 0.481, p = 0.032), but these correlations were not observed for NR1D1 or NR1D2. No association was noted between meal times and the amplitude or the acrophase for any of these three clock genes. These findings suggest that rhythmic expression of the circadian clock gene PER3 is associated with the amount of daily physical activity and physical fitness in older adults.

Exome-wide Association Study Identifies CLEC3B Missense Variant p.S106G as Being Associated With Extreme Longevity in East Asian Populations

Abstract Life span is a complex trait regulated by multiple genetic and environmental factors; however, the genetic determinants of extreme longevity have been largely unknown. To identify the functional coding variants associated with extreme longevity, we performed an exome-wide association study (EWAS) on a Japanese population by using an Illumina HumanExome Beadchip and a focused replication study on a Chinese population. The EWAS on two independent Japanese cohorts consisting of 530 nonagenarians/centenarians demonstrated that the G allele of CLEC3B missense variant p.S106G was associated with extreme longevity at the exome-wide level of significance (p = 2.33×10–7, odds ratio [OR] = 1.50). The CLEC3B gene encodes tetranectin, a protein implicated in the mineralization process in osteogenesis as well as in the prognosis and metastasis of cancer. The replication study consisting of 448 Chinese nonagenarians/centenarians showed that the G allele of CLEC3B p.S106G was also associated with extreme longevity (p = .027, OR = 1.51), and the p value of this variant reached 1.87×10–8 in the meta-analysis of Japanese and Chinese populations. In conclusion, the present study identified the CLEC3B p.S106G as a novel longevity-associated variant, raising the novel hypothesis that tetranectin, encoded by CLEC3B, plays a role in human longevity and aging.

Associations between the orexin (hypocretin) receptor 2 gene polymorphism Val308Ile and nicotine dependence in genome-wide and subsequent association studies

BackgroundMany genetic and environmental factors are involved in the etiology of nicotine dependence. Although several candidate gene variations have been reported by candidate gene studies or genome-wide association studies (GWASs) to be associated with smoking behavior and the vulnerability to nicotine dependence, such studies have been mostly conducted with subjects with European ancestry. However, genetic factors have rarely been investigated for the Japanese population as GWASs. To elucidate genetic factors involved in nicotine dependence in Japanese, the present study comprehensively explored genetic contributors to nicotine dependence by using whole-genome genotyping arrays with more than 200,000 markers in Japanese subjects.ResultsThe subjects for the GWAS and replication study were 148 and 374 patients, respectively. A two-stage GWAS was conducted using the Fagerström Test for Nicotine Dependence (FTND), Tobacco Dependence Screener (TDS), and number of cigarettes smoked per day (CPD) as indices of nicotine dependence. For the additional association analyses, patients who underwent major abdominal surgery, patients with methamphetamine dependence/psychosis, and healthy subjects with schizotypal personality trait data were recruited. Autopsy specimens with various diseases were also evaluated. After the study of associations between more than 200,000 marker single-nucleotide polymorphisms (SNPs) and the FTND, TDS, and CPD, the nonsynonymous rs2653349 SNP (located on the gene that encodes orexin [hypocretin] receptor 2) was selected as the most notable SNP associated with FTND, with a p value of 0.0005921 in the two-stage GWAS. This possible association was replicated for the remaining 374 samples. This SNP was also associated with postoperative pain, the initiation of methamphetamine use, schizotypal personality traits, and susceptibility to goiter.ConclusionsAlthough the p value did not reach a conventional genome-wide level of significance in our two-stage GWAS, we obtained significant results in the subsequent analyses that suggest that the rs2653349 SNP (Val308Ile) could be a genetic factor that is related to nicotine dependence and possibly pain, schizotypal personality traits, and goiter in the Japanese population.

High cardiorespiratory fitness can reduce glycated hemoglobin levels regardless of polygenic risk for Type 2 diabetes mellitus in nondiabetic Japanese men.

High cardiorespiratory fitness (CRF) is associated with a reduced risk of Type 2 diabetes mellitus (T2DM) and improved β-cell function; genetic factors also determine these risks. This cross-sectional study investigated whether CRF modifies the association of polygenic risk of T2DM with glucose metabolism in nondiabetic Japanese men. Fasting plasma glucose, insulin, and glycated hemoglobin (HbA1c) levels were measured in 174 Japanese men (age: 20-79 yr). β-Cell function and insulin resistance were evaluated by calculating HOMA-β and HOMA-IR, respectively. CRF was assessed by measuring maximal oxygen uptake (V̇o2max). Subjects were divided into the low and high CRF groups within each age group according to the median V̇o2max. Eleven single nucleotide polymorphisms (SNPs) associated with T2DM were analyzed and used to calculate genetic risk score (GRS); subjects were divided into the low, middle, and high GRS groups. The high GRS group had higher HbA1c levels than the low GRS group in both the low and high CRF groups (P < 0.05). Furthermore, the individuals with a high GRS had a lower HOMA-β than those with a low GRS regardless of CRF (P < 0.05). In multiple linear regression analysis, although GRS was a significant predictor of HbA1c (β = 0.153, P = 0.025), V̇o2max was also associated with HbA1c (β = -0.240, P = 0.041) independent of GRS. These results suggest that CRF is associated with HbA1c levels independent of GRS derived from T2DM-related SNPs; however, it does not modify the association of GRS with increased HbA1c or impaired β-cell function.

Inverse Association Between Height-Increasing Alleles and Extreme Longevity in Japanese Women

Growth hormone (GH)/insulin-like growth factor-1 (IGF-1)/insulin signaling is one of the most plausible biological pathways regulating aging and longevity. Previous studies have demonstrated that several single nucleotide polymorphisms (SNPs) in the GH/IGF-1/insulin signaling-associated genes influence both longevity and adult height, suggesting the possibility of a shared genetic architecture between longevity and height. We therefore examined the relationship between 30 height-associated SNPs and extreme longevity in a Japanese population consisting of 428 centenarians and 4,026 younger controls. We confirmed that height-increasing genetic scores (HGSs) constructed based on 30 SNPs were significantly associated with height in the controls (p = 6.95 × 10-23). HGS was significantly and inversely associated with extreme longevity in women (p = .011), but not in men, although no SNPs were significantly associated with extreme longevity after Bonferroni correction. The odds ratio for extreme longevity in the lowest HGS group (≤27) and the second lowest HGS group (28-30) relative to the highest HGS group (≥37) was 1.71 (p = .056) and 1.69 (p = .034), respectively, for women. In conclusion, the present study demonstrated an inverse association between height-increasing alleles with extreme longevity in Japanese women, providing novel insight into the genetic architecture of longevity and aging.