Suh-Hang Hank Juo

Negative feedback regulation between microRNA let-7g and the oxLDL receptor LOX-1

Lectin-like oxidized LDL receptor-1 (LOX-1) is a surface scavenger receptor for oxidized low-density lipoprotein (oxLDL). Several transcription factors have been reported to regulate LOX-1 expression. MicroRNAs are small noncoding RNAs that control gene expression, but there have been no reports of LOX-1 expression being regulated by microRNAs. Because the microRNA let-7g has been predicted to bind to LOX-1 mRNA, we investigated whether let-7g can regulate LOX-1 expression. Our experiments first demonstrated that oxLDL can reduce let-7g expression. We later confirmed that there is a let-7g binding site on the 3′-untranslated region of LOX-1 mRNA. We showed that intracellular Ca2+-activated protein kinase C is involved in the oxLDL–LOX-1–let-7g pathway. Bioinformatics predicted that the let-7g promoter has a binding site for the transcriptional repressor OCT-1. We used a promoter assay and chromatin immunoprecipitation to confirm this binding. Consequently, knockdown of OCT-1 was found to increase let-7g expression. Transfection of let-7g inhibited oxLDL-induced LOX-1 and OCT-1 expression, cell proliferation and migration. Mice fed with a high-fat diet showed a decrease in let-7g and an increase in LOX-1 and OCT-1. A study on humans showed the serum levels of let-7g are lower in subjects with hypercholesterolemia compared with normal controls. Our findings identify a negative feedback regulation between let-7g and LOX-1, and indicate that let-7g could be a target to treat cardiovascular disease.

Let-7g Improves Multiple Endothelial Functions Through Targeting Transforming Growth Factor-Beta and SIRT-1 Signaling

OBJECTIVES The present study aimed to explore the role of microribonucleic acid (miRNA) Let-7g in regulating endothelial functions. BACKGROUND Derangement of miRNAs is implicated in the pathogenesis of cardiovascular diseases. Because the transforming growth factor (TGF)-β pathway plays a regulatory role in endothelial functions, miRNAs targeted at TGF-β signal cascade might affect vascular health. METHODS Bioinformatics software predicted that Let-7g can influence the TGF-β pathway by targeting 3 genes. The Let-7gs effects on multiple endothelial functions were first tested in endothelial cells (ECs) and then in apolipoprotein E knockout mice. Blood samples from lacunar stroke patients were also examined to further support Let-7gs effects on human subjects. RESULTS Let-7g was experimentally confirmed to knock down the THBS1, TGFBR1, and SMAD2 genes in the TGF-β pathway. PAI-I, one of the downstream effectors of the TGF-β pathway, was also down-regulated by Let-7g. Let-7g decreased EC inflammation and monocyte adhesion and increased angiogenesis via the TGF-β pathway. Furthermore, Let-7g reduced EC senescence through increasing SIRT-1 protein. Venous injection of Let-7g inhibitor into apolipoprotein E knockout mice caused overgrowth of vascular intima-media, overexpression of PAI-1, increased macrophage infiltration, and up-regulation of TGF-β downstream genes in the carotid arteries. Let-7gs beneficial effects on EC were reduced, whereas the TGF-β pathway was suppressed by ribonucleic acid interference. Restoration of the TGF-β pathway also attenuated the effects of Let-7g overexpression. Low serum levels of Let-7g were associated with increased circulating PAI-1 levels. CONCLUSIONS Decreased Let-7g levels impair endothelial function and increase the risks of cardiovascular diseases through targeting TGF-β and SIRT-1 signaling.

OxLDL causes both epigenetic modification and signaling regulation on the microRNA-29b gene: Novel mechanisms for cardiovascular diseases

MicroRNA-29b has been reported to epigenetically regulate proatherogenic genes in response to oxLDL. Since transcription factors and epigenetic regulations are important mechanisms to regulate gene expression, we investigated whether these mechanisms are involved in oxLDL-induced microRNA-29b upregulation. First, we confirmed that microRNA-29b expression was increased in the aorta of mice fed with a high-fat diet, which was consistent with our previous in vitro findings. Next, we found that oxLDL only activated the microRNA-29b-1/microRNA-29a cluster gene on chromosome 7 but not the other distinct microRNA-29b gene located on chromosome 1. Using the promoter reporter assay and chromatin immunoprecipitation, activator protein-1 (AP-1) was shown to bind to the microRNA-29b-1 promoter. We further identified the signaling pathway of LOX-1/Ca(2+)/ROS/ERK/c-Fos was involved in oxLDL-mediated microRNA-29b overexpression after treating with the MAPTAM (Ca(2+) chelator), NAC (ROS scavenger), U0126 (ERK inhibitor) and c-Fos (one of the AP-1 proteins) shRNA, respectively. To investigate epigenetic regulations, we found that microRNA-29b promoter contained no CpG islands for DNA methylation. Therefore we investigated whether histone modifications influence microRNA-29b promoter activity. We showed that down-regulation of HDAC1 and the modifications on histone 3 lysine 4 (H3K4) and H3K9 significantly affected microRNA-29b expression. Furthermore, knockdown of c-Fos expression attenuated the effect of oxLDL-induced histone modifications on the microRNA-29b gene expression. Taken together, our data suggest that both transcription factor activation and histone modifications are important regulatory mechanisms of oxLDL-induced atherogenic process. This article is part of a Special Issue entitled OxLDL causes both epigenetic modification and signaling regulation on the microRNA-29b gene: Novel mechanisms for cardiovascular diseases.

Decreased microRNA-221 is associated with high levels of TNF-α in human adipose tissue-derived mesenchymal stem cells from obese woman.

Aim: The present study aimed to investigate the regulation and involvement of miR-221 in the differentiation of human adipose tissue-derived mesenchymal stem cells (hASCs). The relationships between miR-221 and pro-inflammatory markers and adipokines were also explored. Methods: Eight adipose tissues were obtained from four obese (mean body mass index (BMI) =31.7 kg/m2) and four lean (mean BMI= 21.5 kg/m2) women. hASCs were induced to differentiate, and the related gene expression were measured in the hASC-differentiated adipocytes using real-time reverse transcriptase polymerase chain reaction (real-time RT-PCR). Results: During adipogenesis, miR-221 was significantly down-regulated; furthermore, miR-221 levels were lower in hASC-differentiated adipocytes from obese subjects than in the corresponding adipocytes from lean subjects. Higher TNF-α mRNA levels were associated with lower levels of miR-221. In addition, the miR-221 levels in the adipocytes were inversely correlated with BMI. Conclusion: Our results support the link between miR-221 and obesity development as well as obesity related inflammatory status.

Matrix metalloproteinase-9 gene polymorphisms in nasal polyposis.

BackgroundMatrix metalloproteinase (MMP) is involved in the upper airway remodeling process. We hypothesized that genetic variants of the MMP-9 gene are associated with cases of chronic rhinosinusitis with nasal polyposis.MethodsWe conducted a case-control study where 203 cases of chronic rhinosinusitis with nasal polyposis and 730 controls were enrolled. Three tagging single nucleotide polymorphisms (SNPs) and one promoter functional SNP rs3918242 were selected. Hardy-Weinberg equilibrium (HWE) was tested for each SNP, and genetic effects were evaluated according to three inheritance modes. Haplotype analysis was also performed. Permutation was used to adjust for multiple testing.ResultsAll four SNPs were in HWE. The T allele of promoter SNP rs3918242 was associated with chronic rhinosinusitis with nasal polyposis under the dominant (nominal p = 0.023, empirical p = 0.022, OR = 1.62) and additive models (nominal p= 0.012, empirical p = 0.011, OR = 1.60). The A allele of rs2274756 has a nominal p value of 0.034 under the dominant model and 0.020 under the additive model. Haplotype analysis including the four SNPs showed a global p value of 0.015 and the most significant haplotype had a p value of 0.0045. We did not see any SNP that was more significant in the recurrent cases.ConclusionsWe concluded that MMP-9 gene polymorphisms may influence susceptibility to the development of chronic rhinosinusitis with nasal polyposis in Chinese population.

Clinical utility of host genetic IL‐28B variants in hepatitis C virus genotype 1 Asian patients retreated with pegylated interferon plus ribavirin

Host interleukin‐28B (IL‐28B) genetic variants determine a sustained virological response (SVR) in hepatitis C virus genotype 1 (HCV‐1) treatment‐naïve patients. Its impact on treatment‐experienced Asian patients with peginterferon/ribavirin in is to be elucidated.

Genotype and Phenotype Predictors of Relapse of Graves' Disease after Antithyroid Drug Withdrawal

Background: For patients with Graves’ disease (GD), the primary goal of antithyroid drug therapy is to temporarily restore the patient to the euthyroid state and wait for a subsequent remission of the disease. This study sought to identify the predictive markers for the relapse of disease. Methods: To do this, we studied 262 GD patients with long enough follow-up after drug withdrawal to determine treatment outcome. The patients were divided into three groups by time of relapse: early relapse group (n = 91) had an early relapse within 9 months, late relapse group (n = 65) had a relapse between 10 and 36 months, and long-term remission group (n = 106) were either still in remission after at least 3 years or relapsed after 3 years of drug withdrawal. We assessed the treatment outcome of 23 SNPs of costimulatory genes, phenotype and smoking habits. We used permutation to obtain p values for each SNP as an adjustment for multiple testing. Cox proportional hazards models was performed to assess the strength of association between the treatment outcome and clinical and laboratory variables. Results: Four SNPs were significantly associated with disease relapse: rs231775 (OR 1.96, 95% CI 1.18–3.26) at CTLA-4 and rs745307 (OR 7.97, 95% CI 1.01–62.7), rs11569309 (OR 8.09, 95% CI 1.03–63.7), and rs3765457 (OR 2.60, 95% CI 1.08–6.28) at CD40. Combining risk alleles at CTLA-4 and CD40 improved the predictability of relapse. Using 3 years as the cutoff point for multivariate analysis, we found several independent predictors of disease relapse: number of risk alleles (HR 1.30, 95% CI 1.09–1.56), a large goiter size at the end of the treatment (HR 1.30, 95% CI 1.05–1.61), persistent TSH-binding inhibitory Ig (HR 1.64, 95% CI 1.15–2.35), and smoking habit (HR 1.60, 95% CI 1.05–2.42). Conclusion: Genetic polymorphism of costimulatory genes, smoking status, persistent goiter, and TSH-binding inhibitory Ig predict disease relapse.

Predictors of Carotid Intima-Media Thickness and Plaque Progression in a Chinese Population.

AIM Atherosclerotic diseases are the leading cause of death worldwide. Longitudinal changes in carotid intima-media thickness (IMT) and plaque are being increasingly used as markers of atherosclerosis progression and may predict future cardiovascular events. This study aimed to investigate the predictors of carotid IMT and plaque progression in a Chinese population and to determine whether these predictors differ by gender. METHODS Segment-specific carotid IMT and plaque were measured in 712 stroke- and myocardial infarction-free subjects at baseline and after an average interval of 4.3±0.9 years. Multivariate linear regression and logistic regression analyses were conducted to investigate the predictive effect of age, gender, and cardiovascular risk factors on carotid IMT and plaque progression. Gender-specific analyses were also performed. RESULTS Overall, age and smoking were predictors of common carotid artery IMT progression (adjusted p＜0.001 and p=0.045, respectively). Age, hypertension, and use of antihypertensive medication were predictors of bifurcation IMT progression (adjusted p＜0.001, p=0.033, and p＜0.001, respectively). The use of antihypertensive medication was associated with less annual IMT progression in hypertensive subjects than in those who did not take medication, which was most prominent in the bifurcation segment. In addition, most predictors of IMT progression were identified in women in a gender-specific analysis. For plaque progression, age and gender were independent predictors. CONCLUSIONS The predictors of carotid atherosclerosis progression were gender and segment specific. The detection and control of hypertension may prevent atherosclerosis progression, particularly in women.

A Functional Polymorphism at the FGF10 Gene Is Associated With Extreme Myopia

PURPOSE Fibroblast growth factor-10 (FGF10) can modulate extracellular matrix associated genes and, therefore, it could be a myopia susceptibility gene. This study used an animal model, single nucleotide polymorphisms (SNPs) association, and genetic functional assay to evaluate FGF10 gene for myopia. METHODS The expression levels of FGF10 gene were compared among the form deprivation myopic (FDM) eyes, the fellow eyes of the FDM group, and the healthy eyes of experimental mice. In the present study 1020 cases (≤-6.0 diopters [D]) and 960 controls (≥-1.5 D) were enrolled from a Chinese population. Eight tagging SNPs were genotyped to test for an association between genotypes and myopia. The luciferase reporter assay was conducted for the particular SNP to assess the allelic effect on gene expression. RESULTS The sclera of FDM eyes had a 2.57-fold higher level of FGF10 mRNA (P = 0.018) than the fellow eyes. Although no SNP was associated with high myopia, SNP rs339501 was significantly associated with extreme myopia (≤-10 D, P = 0.008) and the odds ratio (OR) was 1.58 for G allele carriers. The luciferase assay showed that the risk G allele significantly caused a higher expression level than the A allele (P = 0.011). CONCLUSIONS The evidence suggested FGF10 to be a risk factor for myopia. The sclera of myopic eyes had higher FGF10 levels. The risk G allele of SNP rs339501 was associated with extreme myopia in human and caused a higher gene expression in the luciferase assay. It is concluded that the FGF10 could have been involved in the development of myopia.

Lack of association between a functional variant of the BRCA-1 related associated protein (BRAP) gene and ischemic stroke

BackgroundAtherosclerosis shares common pathogenic features with myocardial infarction (MI) and ischemic stroke. BRCA-1 associated protein (BRAP), a newly identified risk gene for MI, aggravates the inflammatory response in atherosclerosis. The aim of this study was to test the association between the BRAP gene and stroke in a Taiwanese population.MethodsA total of 1,074 stroke patients and 1,936 controls were genotyped for the functional SNP rs11066001. In our previous studies, the rare allele of this SNP has been repeatedly shown to exert a recessive effect. Therefore, in the current study, we tested for the same recessive model. First, the genotype distributions between all the controls and all the stroke cases were compared. Then to reduce heterogeneity, we explored several population subsets by selecting young stroke subjects (using 45 years of age as the cutoff point), age- and sex-comparable controls, plaque-free controls, and stroke subtypes.ResultsWe did not find any significant association for the entire data set (OR = 0.94, p = 0.74) or for the subset analyses using age- and sex-comparable controls (p = 0.70) and plaque-free controls (p = 0.91). Analyses of the four stroke subtypes also failed to show any significant associations (p = 0.42 – 0.98). For both young and old subjects, the GG genotype of rs11066001 was similar in the stroke cases and unmatched controls (8.1% vs. 9.4% in young subjects and 8.0% vs. 7.8% in old subjects). Comparing stroke cases with plaque-free controls also failed to find any significant association.ConclusionsThe BRAP polymorphism may not play an important role in ischemic stroke in the studied population.