Naoharu Iwai

Background: MicroRNAs (miRNAs) are endogenous small RNAs that are 21-25 nucleotides in length. Recently, plasma miRNAs have been reported to be sensitive and specific biomarkers of various tissue injuries and pathological conditions. The goal of this study was to assess plasma miRNA profiles and to identify plasma miRNAs that are differentially expressed in patients with heart failure. Methods and Results: A total of 33 patients with ischemic heart diseases and 17 asymptomatic controls were recruited. In 10 patients with heart failure, miRNAs were assessed at both NYHA IV and III. miRNA array analyses were found to be not appropriate for plasma miRNA profiling. The plasma concentrations of well-characterized miRNAs (miR-126, 122 and 499) were assessed by a real-time reverse transcription-polymerase chain reaction using an artificial small RNA as an internal standard. Plasma concentrations of miR-126 were negatively correlated with age and logBNP. In 10 patients with heart failure, plasma concentrations of miR-126 were up-regulated with improvement of the NYHA class from IV to III. Conclusions: The plasma concentration of miR-126 was negatively correlated with age and NYHA class, and could be a useful biomarker for heart failure. (Circ J 2011; 75: 336-340)

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Background: MicroRNAs (miRNAs) are endogenous small RNAs of 21–25 nucleotides that can pair with sites in 3′ untranslated regions in mRNAs of protein-coding genes to downregulate their expression. Recently, circulating miRNAs have been reported as promising biomarkers for various pathologic conditions. We assessed the hypothesis that miRNAs may leak into the circulating blood from injured cells and thereby serve as biomarkers for identifying the injured cell type.Methods: We used isoproterenol-induced myocardial injury in rats as a model and miRNA array analyses to identify candidate miRNAs specifically produced in the ventricles of the heart. Individual miRNA concentrations were measured by real-time reverse-transcription PCR. Plasma cardiac troponin I (cTnI) concentrations were measured with an ELISA.Results: Array analyses revealed miR-208 to be produced exclusively in the heart, and we selected this miRNA as a possible biomarker of myocardial injury. Plasma concentrations of miR-208 increased significantly (P < 0.0001) after isoproterenol-induced myocardial injury and showed a similar time course to the concentration of cTnI, a classic biomarker of myocardial injury.Conclusions: The plasma concentration of miR-208 may be a useful indicator of myocardial injury. Our results suggest that profiling of circulating miRNAs may help identify promising biomarkers of various pathologic conditions.

Purpose: MicroRNA-182 (miR-182) is expressed abundantly in the mammalian retina and is therefore thought to perform important roles for the retinal development and the function. To test this hypothesis, we generated miR-182 knockout mice. Methods: northern blotting was performed to confirm the robust expression of miR-182 in the eye. The precursor sequence of miR-182 was replaced by the neomycin resistance gene under the control of the phosphoglycerate kinase 1 promoter in a targeting construct. The targeting vector was linearized and transfected into embryonic stem (ES) cells. Recombinant ES clones were selected and injected into blastocysts to generate male chimeras. Heterozygous and homozygous mice were obtained after five generations of backcrossing and were confirmed using genotyping and northern blotting. Results: Heterozygous (+/-) and homozygous (-/-) knockout mice were morphologically normal, viable, and fertile. Immunohistochemical analysis of the miR-182-deficient retinas did not reveal any apparent structural abnormalities in the retinas. Consistently, global expression profiling using a repeated microarray did not identify significant fluctuations for potential target genes. Conclusions: We successfully generated miR-182 knockout mice and characterized the resulting miR-182-depleted retina. This is the first report describing the targeted deletion of a single miRNA that is highly expressed in the retina. The absence of significant transcriptional and phenotypic changes in miR-182-depleted retinas suggests that miR-182 is not a major determinant of retinal development or delamination. Further studies are required to elucidate any functional changes in the retina.

Hypertension Research, official publication of the Japanese Society of Hypertension, publishes papers reporting original clinical and experimental research in the field of hypertension and related cardiovascular diseases.

Aldosterone plays essential roles in body fluid and electrolyte homeostasis and blood pressure. However, the association between polymorphisms in the CYP11B2 gene and hypertension is controversial. We resequenced CYP11B1 and CYP11B2 and identified 35 polymorphisms in this region. We performed association studies between the plasma aldosterone concentration and 13 polymorphisms in this region in 1443 subjects. The subjects were all obtained from the Suita Cohort Study. Multiple regression analysis indicated that aldosterone levels were determined by renin activity, age, total cholesterol, and hematocrit. Residuals of the aldosterone levels after adjusting for these confounding factors were nominally associated with the T(−344)C ( P =0.0026), C(595)T ( P =0.0180), −(4837)C ( P =0.0310), and G(4936)A ( P =0.0498) polymorphisms. Only the T(−344)C polymorphism was significantly associated with the aldosterone level after a correction for multiple testing (Bonferroni). A significant interaction was observed between the T(−344)C polymorphism and renin activity in determining aldosterone levels. Moreover, a significant interaction was observed in 2063 subjects between urinary sodium excretion, which reflects sodium intake, and the T(−344)C polymorphism in determining systolic blood pressure. Only subjects with the TT genotype showed a positive correlation between urinary sodium excretion and systolic blood pressure. In vitro experiments confirmed the functional significance of this T(−344)C polymorphism in terms of angiotensin II reactivity. Thus, the T(−344)C polymorphism in CYP11B2 appears to affect salt sensitivity in Japanese and to have clinical significance.

The identification of genes that contribute to essential hypertension has been hampered because of a lack of statistical power and problems with multiple testing. In the present study, we performed association analyses between the 161 single nucleotide polymorphisms of 10 candidate genes and hypertension in a Japanese population recruited from the Suita Study (n=3654). We found that 5 polymorphisms in the 3 genes ( SLC9A2 , UMOD , and ELN ) were associated with hypertension status, and 4 of these 5 polymorphisms were also associated with blood pressure values with a classical criterion of P ELN 3′-untranslated region (−/A) polymorphism was found to significantly affect pulse wave velocity, an indicator of arterial stiffness. Associations of the ELN 3′-untranslated region (−/A) polymorphism with hypertension and pulse wave velocity were reconfirmed in another set of the study population. Thus, ELN seems to contribute to blood pressure regulation by affecting arterial stiffness in Japanese.

MicroRNAs (miRNAs) have been suggested to play important roles in cell proliferation, apoptosis, and differentiation. In this study, we examined miRNA expression profiles during 3T3-L1 pre-adipocyte differentiation. We constructed miRNA libraries from pre- and post-differentiated 3T3-L1 cells, and identified the expression of 77 previously reported miRNAs and 3 new miRNAs. Next, we investigated the expression levels of 102 miRNAs, including those identified in the libraries, during adipogenesis by Northern blot analysis. Sixty-five miRNAs were detected and the expression of 21 miRNAs was up- or down-regulated during adipogenesis. Intriguingly, changes in the miRNA expression pattern were observed at day 9, when lipid droplets were visible, but not at days 1, 2, or 5 after the induction of differentiation. Antisense inhibition of the up-regulated miRNAs did not affect 3T3-L1 pre-adipocyte differentiation. Although these miRNAs may be involved in modulating adipocyte function, mild down-modulations of the up-regulated miRNAs do not appear to affect 3T3-L1 pre-adipocyte differentiation.

Nanoscale materials are presently under development for diagnostic (nanomedicine) and electronic purposes. In contrast to the potential benefits of nanotechnology, the effects of nanomaterials on human health are poorly understood. Nanomaterials are known to translocate into the circulation and could thus directly affect vascular endothelial cells (ECs), causing vascular injury that might be responsible for the development of atherosclerosis. To explore the direct effects of nanomaterials on endothelial toxicity, human umbilical vein ECs were treated with 1–100 μg/ml hydroxyl fullerene [C₆₀(OH)₂₄; mean diameter, 7.1 ± 2.4 nm] for 24 h. C₆₀(OH)₂₄ induced cytotoxic morphological changes such as cytosolic vacuole formation and decreased cell density in a dose-dependent manner. Lactate dehydrogenase assay revealed that a maximal dose of C₆₀(OH)₂₄ (100 μg/ml) induced cytotoxic injury. Proliferation assay also showed that a maximal dose of C₆₀(OH)₂₄ inhibited EC growth. C₆₀(OH)₂₄ did not seem to induce apoptosis but caused the accumulation of polyubiquitinated proteins and facilitated autophagic cell death. Formation of autophagosomes was confirmed on the basis of Western blot analysis using a specific marker, light chain 3 antibody, and electron microscopy. Chronic treatment with low-dose C₆₀(OH)₂₄ (10 μg/ml for 8 days) inhibited cell attachment and delayed EC growth. In the present study, we have examined, for the first time, the toxicity of water-soluble fullerenes to ECs. Although fullerenes changed morphology in a dose-dependent manner, only maximal doses of fullerenes caused cytotoxic injury and/or death and inhibited cell growth. EC death seemed to be caused by activation of ubiquitin-autophagy cell death pathways. Although exposure to nanomaterials appears to represent a risk for cardiovascular disorders, further in vivo validations are necessary.

Background Recently, the Framingham Heart Study reported that genetic variations in CCL2 influence serum levels of monocyte chemoattractant protein-1 (MCP-1) and the incidence of myocardial infarction (MI). The purpose of the present study was to investigate the possible involvement of CCL2 in the pathogenesis of atherosclerosis and MI in Japanese. Methods and Results Multiple regression analysis indicated that the MCP-1 levels were significantly influenced by various factors including age, body mass index, smoking, alcohol intake, high density lipoprotein-cholesterol, and systolic blood pressure. Moreover, the serum MCP-1 level was significantly correlated with intima - media thickness (pCCL2 in a large community-based population and in subjects with MI found that the A(-2138)T polymorphism affected the serum MCP-1 level in a subgroup of subjects 65 years and older. However, no significant differences in the frequencies of any of the polymorphisms or haplotypes were found between subjects with and without MI. None of the polymorphisms in CCL2 affected carotid atherosclerosis. Conclusions The serum MCP-1 level was a good surrogate marker of atherosclerosis in the present study population. Although genetic variations in CCL2 may have some influence on MCP-1 production, their influence does not seem to contribute appreciably to atherosclerosis in Japanese. The present results did not support the recently published findings from the Framingham Heart Study. The discrepancy between the 2 studies may be related to differences in confounding factors that contribute to MCP-1 levels and in the haplotype structure of the 2 populations. (Circ J 2006; 70: 805 - 809)