👤 Haizheng Yu

Numerous studies have revealed the high diversity of cyanophages in marine and freshwater environments, but little is currently known about the diversity of cyanophages in paddy fields, particularly in Northeast (NE) China. To elucidate the genetic diversity of cyanophages in paddy floodwaters in NE China, viral capsid assembly protein gene (g20) sequences from five floodwater samples were amplified with the primers CPS1 and CPS8. Denaturing gradient gel electrophoresis (DGGE) was applied to distinguish different g20 clones. In total, 54 clones differing in g20 nucleotide sequences were obtained in this study. Phylogenetic analysis showed that the distribution of g20 sequences in this study was different from that in Japanese paddy fields, and all the sequences were grouped into Clusters α, β, γ and ε. Within Clusters α and β, three new small clusters (PFW-VII∼-IX) were identified. UniFrac analysis of g20 clone assemblages demonstrated that the community compositions of cyanophage varied among marine, lake and paddy field environments. In paddy floodwater, community compositions of cyanophage were also different between NE China and Japan. Show less

To compare the transcriptome of esophageal cancer cells (EC9706), human mesenchymal stem cells (MSCs), and after fusion of esophageal cancer cells with MSCs, and to further study their different expression profiles and the changes of their signaling pathways. We examined the gene expression profiles of these cells with transcriptome microarray using LIMMA package and several web-based applications, such as DAVID, ToppGene and MSigDB. The resulting sets of differentially expressed genes (DEGs) were comprehensively analyzed to identify the pathways and their changes after the cell fusion. A total of 4 548 significantly DEGs among the three cell lines were found by LIMMA. Three functional annotation web tools predicted that DNA damage repair, cell cycle arrest and apoptosis pathways were enriched. Total DEGs were mapped to the canonic pathways with KEGGanim which depicted that the core genes of DNA damage repair, cell cycle arrest and pro-apoptosis were up-regulated in fusion cells, and they mightbe combined to respond the fusion-induced damage stress. The up-regulation of suppressive factor DUSP6 might feedback inhibit the MAPK signaling pathway in the fusion cells, too. Transcriptome analysis suggests that hMSCs and EC9706 cell fusion may inhibit growth of EC cells by induction of pro-apoptotic signaling and DUSP6 negative feedback inhibition mechanism. In addition, the changes of immune regulation-related and differentiation-related genes indicate that the fusion cells inherited certain immune-suppressive function from the stem cells. Show less

The glycosyltransferase gene, Ext1, is essential for heparan sulfate production. Induced deletion of Ext1 selectively in Mx1-expressing bone marrow (BM) stromal cells, a known population of skeletal stem/progenitor cells, in adult mice resulted in marked changes in hematopoietic stem and progenitor cell (HSPC) localization. HSPC egressed from BM to spleen after Ext1 deletion. This was associated with altered signaling in the stromal cells and with reduced vascular cell adhesion molecule 1 production by them. Further, pharmacologic inhibition of heparan sulfate mobilized qualitatively more potent and quantitatively more HSPC from the BM than granulocyte colony-stimulating factor alone, including in a setting of granulocyte colony-stimulating factor resistance. The reduced presence of endogenous HSPC after Ext1 deletion was associated with engraftment of transfused HSPC without any toxic conditioning of the host. Therefore, inhibiting heparan sulfate production may provide a means for avoiding the toxicities of radiation or chemotherapy in HSPC transplantation for nonmalignant conditions. Show less

Carbohydrate-response element binding protein (ChREBP) plays a key role in regulating glucose metabolism and de novo lipogenesis in metabolic tissues and cancer cells. Here we report that ChREBP is also a critical regulator of the metabolic alterations induced during human cytomegalovirus (HCMV) infection. The expression of both ChREBP-α and ChREBP-β is robustly induced in HCMV-infected human fibroblasts; this induction is required for efficient HCMV infection. Depletion of ChREBP in HCMV-infected cells results in reduction of HCMV-induced glucose transporter 4 and glucose transporter 2 expression, leading to inhibition of glucose uptake, lactate production, nucleotide biosynthesis, and NADPH generation. We previously reported that HCMV infection induces lipogenesis through the activation of sterol regulatory element binding protein 1, which is mediated by the induction of PKR-like endoplasmic reticulum kinase. Data from the present study show that HCMV-induced lipogenesis is also controlled by the induction of ChREBP, in a second mechanism involved in the regulation of HCMV-induced de novo lipogenesis. These results suggest that ChREBP plays a key role in reprogramming glucose and lipid metabolism in HCMV infection. Show less

Inflammation marks all stages of atherogenesis. DNA hypermethylation in the whole genome or specific genes is associated with inflammation and cardiovascular diseases. Therefore, we aimed to study whether inhibiting DNA methylation by DNA methyltransferase inhibitor 5-aza-2'-deoxycytidine (5-aza-dC) ameliorates atherosclerosis in low-density lipoprotein receptor knockout (Ldlr(-/-)) mice. Ldlr(-/-) mice were fed an atherogenic diet and adminisered saline or 5-aza-dC (0.25 mg/kg) for up to 30 weeks. 5-aza-dC treatment markedly decreased atherosclerosis development in Ldlr(-/-) mice without changes in body weight, plasma lipid profile, macrophage cholesterol levels and plaque lipid content. Instead, this effect was associated with decreased macrophage inflammation. Macrophages with 5-aza-dC treatment had downregulated expression of genes involved in inflammation (TNF-α, IL-6, IL-1β, and inducible nitric oxidase) and chemotaxis (CD62/L-selectin, chemokine [C-C motif] ligand 2/MCP-1 [CCL2/MCP-1], CCL5, CCL9, and CCL2 receptor CCR2). This resulted in attenuated macrophage migration and adhesion to endothelial cells and reduced macrophage infiltration into atherosclerotic plaques. 5-aza-dC also suppressed macrophage endoplasmic reticulum stress, a key upstream signal that activates macrophage inflammation and apoptotic pathways. Finally, 5-aza-dC demethylated liver X receptor α (LXRα) and peroxisome proliferator-activated receptor γ1 (PPARγ1) promoters, which are both enriched with CpG sites. This led to overexpression of LXRα and PPARγ, which may be responsible for 5-aza-dC's anti-inflammatory and atheroprotective effect. Our findings provide strong evidence that DNA methylation may play a significant role in cardiovascular diseases and serve as a therapeutic target for prevention and treatment of atherosclerosis. Show less

This study was designed to investigate the direct effects of fatty acids (FAs) on the cell viability and the expression levels of genes involved in lipid metabolism in LO2 human liver cells. Palmitate (PA), oleate (OA) and docosahaexenoic acid (DHA) were used to represent saturated, mono-unsaturated and polyunsaturated FAs, respectively. At concentrations of ≤3.2 µg/ml, treatment with single FAs increased the viability of the LO2 cells. At FA concentrations of >3.2 µg/ml, cell viability following OA treatment was increased, but PA or DHA treatment at these concentrations reduced cell viability. Administration of mixtures of these FAs in three ratios (PA:OA:DHA = 1:2:1, 1:1:1 and 1:1:2, respectively) increased the cell viability compared with the control group. The intracellular triglyceride (TG) levels following all types of treatment were significantly increased and the accumulation of TGs was markedly increased with high doses of DHA. In addition, peroxisome proliferator-activated receptor-γ was significantly upregulated in all groups, with the exception of the 1:1:1 group at 3.2 µg/ml and the 1:1:2 group at 12.8 µg/ml. The expression levels of sterol regulatory-element binding protein‑1c, liver X receptor α and apolipoprotein C‑I were significantly reduced in all groups with the exception of the DHA‑treated group and the 1:2:1 groups at 3.2 and 12.8 µg/ml. In conclusion, these results indicate that the type, concentration and mixture ratios of FAs are all important in determining the cell viability and lipid metabolism-related gene expression in LO2 hepatocytes. Show less

Liver X receptors (LXRs) have been recognized as a promising therapeutic target for atherosclerosis; however, their role in insulin sensitivity is controversial. Adiponectin plays a unique role in maintaining insulin sensitivity. Currently, no systematic experiments elucidating the role of LXR activation in insulin function based on adiponectin signaling have been reported. Here, we investigated the role of LXR activation in insulin resistance based on adiponectin signaling, and possible mechanisms. C57BL/6 mice maintained on a regular chow received the LXR agonist, T0901317 (30 mg/kg.d) for 3 weeks by intraperitoneal injection, and differentiated 3T3-L1 adipocytes were treated with T0901317 or GW3965. T0901317 treatment induced significant insulin resistance in C57BL/6 mice. It decreased adiponectin gene transcription in epididymal fat, as well as serum adiponectin levels. Activity of AMPK, a key mediator of adiponectin signaling, was also decreased, resulting in decreased Glut-4 membrane translocation in epididymal fat. In contrast, adiponectin activity was not changed in the liver of T0901317 treated mice. In vitro, both T0901317 and GW3965 decreased adiponectin expression in adipocytes in a dose-dependent manner, an effect which was diminished by LXRα silencing. ChIP-qPCR studies demonstrated that T0901317 decreased the binding of PPARγ to the PPAR-responsive element (PPRE) of the adiponectin promoter in a dose-dependent manner. Furthermore, T0901317 exerted an antagonistic effect on the expression of adiponectin in adipocytes co-treated with 3 µM Pioglitazone. In luciferase reporter gene assays, T0901317 dose-dependently inhibited PPRE-Luc activity in HEK293 cells co-transfected with LXRα and PPARγ. These results suggest that LXR activation induces insulin resistance with decreased adiponectin signaling in epididymal fat, probably due to negative regulation of PPARγ signaling. These findings indicate that the potential of LXR activation as a therapeutic target for atherosclerosis may be limited by the possibility of exacerbating insulin resistance-related disease. Show less

Vascular endothelial injury is a major cause of many cardiovascular diseases. The proliferation and migration of endothelial progenitor cells (EPCs) play a pivotal role in endothelial regeneration and repair after vascular injury. Recently, liver X receptor (LXR) activation has been suggested as a potential target for novel therapeutic interventions in the treatment of cardiovascular disease. However, the effects of LXR activation on endothelial regeneration and repair, as well as EPC function, have not been investigated. In the present study, we demonstrate that LXRs, including LXRα and LXRβ, are expressed and functional in rat bone marrow-derived EPCs. Treatment with an LXR agonist, TO901317 (TO) or GW3965 (GW), significantly increased the proliferation and migration of EPCs, as well as Akt and eNOS phosphorylation in EPCs. Moreover, LXR agonist treatment enhanced the expression and secretion of vascular endothelial growth factor in EPCs. LXR agonists accelerated re-endothelialization in injured mouse carotid arteries in vivo. These data confirm that LXR activation may improve EPC function and endothelial regeneration and repair after vascular injury by activating the PI3K/Akt/eNOS pathway. We conclude that LXRs may be attractive targets for drug development in the treatment of cardiovascular diseases associated with vascular injury. Show less

The goal of this study was to investigate the effect of octreotide on the expression of intestinal fat absorption-associated apolipoproteinB48 (apoB48), microsomal triglyceride transfer protein (MTP) and apolipoproteinAIV (apoAIV) in a high-fat diet-induced obesity rat model. Sprague-Dawley rats were placed into a control or high-fat diet group. Obese rats from the high-fat diet group were further divided into an obese group and an octreotide-treated group. Rats in the octreotide-treated group were subcutaneously injected with octreotide (40 μg/kg body weight) twice daily for 8 d. Body weight, fasting plasma glucose (FPG), fasting serum insulin, triglyceride (TG), total cholesterol (TC), and high density lipoprotein-cholesterol (HDL-C) were measured. Intestinal MTP, apoB48, and apoAIV expression levels were determined by real-time polymerase chain reaction, Western blot, or enzyme-linked immunosorbent assay analysis. We found high-fat diet-induced obesity rats express more apoB, MTP, and apoAIV mRNA as well as apoB48 and MTP protein in the intestine than normal chow-fed rats. This observation occurred along with increased body weight, FPG, TG, TC, fasting serum insulin, and Homeostatic Model Assessment value. Octreotide intervention significantly decreased body weight and blood parameters, and down-regulated expression of apoB mRNA and apoB48 protein, as well as MTP mRNA and proteins. However, apoAIV mRNA was not significantly different between obese and octreotide-treated rats although it was decreased by 47%. High-fat diet-induced obesity is associated with increased expression of apoB48, MTP, and apoAIV in the intestine. Octreotide intervention inhibited the overexpression of apoB48 and MTP, and consequently brought about reduced fat absorption and weight loss. Show less

We assessed the associations between the APOA5  -1131T>C polymorphism and lipid parameters and other risk factors of the metabolic syndrome in Korean subjects. A total of 2,901 participants from 20 oriental medical hospitals in Korea were enrolled between 2006 and 2011. According to the modified National Cholesterol Education Program Adult Treatment Panel III definitions, subjects were classified into the metabolic syndrome group and control group. The APOA5  -1131T>C genotype was significantly associated with serum high-density lipoprotein cholesterol levels (effect = - 1.700 mg/dL, P=6.550-E07) in the total study population after adjustment for differences in age and gender. The association of the APOA5  -1131T>C genotype with serum log-transformed triglyceride was also significant in an additive genetic model (effect = 0.056 mg/dL, P=2.286E-19). After adjustment for age and gender, we determined that the odds ratio for the occurrence of the metabolic syndrome was 1.322 for C-allele carriers in the additive model (95% CI = [1.165 - 1.501], P=1.48E-05). In the current study, we demonstrated that the APOA5  -1131T>C polymorphism is associated with the metabolic syndrome because of its remarkable effect on serum triglyceride levels in Korean subjects. Show less

In this study, we evaluated the reproducibility of abundant urine protein depletion by hexapeptide-based library beads and an antibody-based affinity column using the iTRAQ technique. The antibody-based affinity-depletion approach, which proved superior, was then applied in conjunction with iTRAQ to discover proteins that were differentially expressed between pooled urine samples from hernia and bladder cancer patients. Several proteins, including seven apolipoproteins, TIM, SAA4, and proEGF were further verified in 111 to 203 individual urine samples from patients with hernia, bladder cancer, or kidney cancer. Six apolipoproteins (APOA1, APOA2, APOB, APOC2, APOC3, and APOE) were able to differentiate bladder cancer from hernia. SAA4 was significantly increased in bladder cancer subgroups, whereas ProEGF was significantly decreased in bladder cancer subgroups. Additionally, the combination of SAA4 and ProEGF exhibited higher diagnostic capacity (AUC=0.80 and p<0.001) in discriminating bladder cancer from hernia than either marker alone. Using MetaCore software to interpret global changes of the urine proteome caused by bladder cancer, we found that the most notable alterations were in immune-response/alternative complement and blood-coagulation pathways. This study confirmed the clinical significance of the urine proteome in the development of non-invasive biomarkers for the detection of bladder cancer. In this study, we evaluated the reproducibility of abundant urine protein depletion by hexapeptide-based library beads and an antibody-based affinity column using the iTRAQ technique. The antibody-based affinity-depletion approach, which proved superior, was then applied in conjunction with iTRAQ to discover proteins that were differentially expressed between pooled urine samples from hernia and bladder cancer patients. Several proteins, including seven apolipoproteins, TIM, SAA4, and proEGF were further verified in 111 to 203 individual urine samples from patients with hernia, bladder cancer, or kidney cancer. SAA4 was significantly increased in bladder cancer subgroups, whereas ProEGF was significantly decreased in bladder cancer subgroups. Additionally, the combination of SAA4 and ProEGF exhibited higher diagnostic capacity in discriminating bladder cancer from hernia than either marker alone. A marker panel composed by two novel biomarker candidates, SAA4 and proEGF, was first discovered and verified successfully using Western blotting. To the best of our knowledge, the associations of urinary SAA4 and proEGF with bladder tumor and kidney cancer have not been mentioned before. In the present study, we discovered and verified SAA4 and proEGF as potential bladder cancer biomarker for the first time. Show less

Mouse embryonic fibroblasts (MEFs) differentiate into fully functional chondrocytes in response to bone morphogenetic protein-2 (BMP-2). However, the comprehensive proteomic aspect of BMP-2-induced chondrogenesis remains unknown. We took advantage of quantitative proteomic analysis based on isobaric tag for relative and absolute quantitation (iTRAQ) and on-line 2D nano-liquid chromatography/tandem mass spectrometry (LC/MS/MS) to identify proteins differentially expressed during BMP-2-induced chondrogenic differentiation of MEFs. We found 85 downregulated proteins, and ingenuity pathways analysis (IPA) revealed a protein-protein network with chromodomain-helicase-DNA-binding protein 4 (Chd4) in the center. Chromatin immunoprecipitation (ChIP) and nuclease hypersensitivity assays showed that Chd4, interacting with Hdac1/2, cooperates with its related proteins Kap1 and Cbx1 to bind at -207/-148 of the Sox9 promoter. We also provided evidence that let-7a targets the 3'UTR of Chd4 to promote chondrogenesis of MEFs. Together, our findings indicate that BMP-2 induced the upregulation of let-7a, targeting Chd4 and positively controlling the chondrogenic differentiation of MEFs. These findings illustrate epigenetic regulation of the chondrogenic differentiation process and also expand the understanding of the involved intracellular mechanisms. Show less

Plasma lipid levels are important risk factors for cardiovascular disease and are influenced by genetic and environmental factors. Recent genome wide association studies (GWAS) have identified several lipid-associated loci, but these loci have been identified primarily in European populations. In order to identify genetic markers for lipid levels in a Chinese population and analyze the heterogeneity between Europeans and Asians, especially Chinese, we performed a meta-analysis of two genome wide association studies on four common lipid traits including total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL) and high-density lipoprotein cholesterol (HDL) in a Han Chinese population totaling 3,451 healthy subjects. Replication was performed in an additional 8,830 subjects of Han Chinese ethnicity. We replicated eight loci associated with lipid levels previously reported in a European population. The loci genome wide significantly associated with TC were near DOCK7, HMGCR and ABO; those genome wide significantly associated with TG were near APOA1/C3/A4/A5 and LPL; those genome wide significantly associated with LDL were near HMGCR, ABO and TOMM40; and those genome wide significantly associated with HDL were near LPL, LIPC and CETP. In addition, an additive genotype score of eight SNPs representing the eight loci that were found to be associated with lipid levels was associated with higher TC, TG and LDL levels (P = 5.52 × 10(-16), 1.38 × 10(-6) and 5.59 × 10(-9), respectively). These findings suggest the cumulative effects of multiple genetic loci on plasma lipid levels. Comparisons with previous GWAS of lipids highlight heterogeneity in allele frequency and in effect size for some loci between Chinese and European populations. The results from our GWAS provided comprehensive and convincing evidence of the genetic determinants of plasma lipid levels in a Chinese population. Show less

Dual-specificity phosphatase 6 (DUSP6), a specific negative feedback regulator of phosphorylated extracellular signal-regulated kinase, was found to play an important role in numerous types of solid tumors as a tumor suppressor. In this study, 64.2% (61/95) of esophageal squamous cell carcinoma (ESCC) specimens studied exhibited reduced DUSP6 protein expression, compared with 91% (81/89) of normal esophageal specimens that displayed moderate or strong DUSP6 protein expression in tissue microarray analysis. In total, 36.8% (7/19) of the tumor biopsies displayed at least two-fold downregulation of DUSP6 compared with their paired normal counterparts, by qPCR. Significant loss of DUSP6 was observed in EC9706 and KYSE150 ESCC cell lines by immunoblotting assay. Low DUSP6 protein expression was significantly associated with pathological grade in ESCC by immunohistochemistry (P<0.05). Treatment with 5-aza-2'-deoxycytidine restored DUSP6 expression in the two ESCC cell lines, and the expression varied according to the drug concentration. Methylation-specific PCR analysis showed methylation-specific products in the two ESCC cell lines. We observed significant differences in the early and total apoptotic proportion between the control and experimental groups of the two ESCC cell lines and their transfectants (P<0.001) by annexin/propidium iodide assay. The presence of cleaved PARP product, a marker of caspase-mediated apoptosis, expressed in the two pCMV-DUSP6 transfectants in marked contrast to the parental and pCMV-transfected EC9706 and KYSE150 cells, was observed by immunoblotting. Overall, our results support the role of DUSP6 as a novel candidate tumor suppressor gene in ESCC, which may be a potential prognostic marker for ESCC. Show less

Prostate cancer is a heterogeneous genetic disease, and molecular methods for predicting prognosis in patients with aggressive form of the disease are urgently needed to better personalize treatment approaches. The objective was to identify host genetic variations in candidate steroidogenic genes affecting hormone levels and prostate cancer progression. The study examined two independent cohorts composed of 526 Caucasian men with organ-confined prostate cancer and 601 Taiwanese men on androgen-deprivation therapy. Caucasians were genotyped for 109 haplotype-tagging single-nucleotide polymorphisms (SNP) in CYP17A1, ESR1, CYP19A1, and HSD3B1, and their prognostic significance on disease progression was assessed using Kaplan-Meier survival curves and Cox regression models. Positive findings, including previously identified SRD5A1, SRD5A2, HSD17B2, HSD17B3, and HSD17B12 polymorphisms, were then explored in Taiwanese men (n = 32 SNPs). The influence of positive markers on the circulating hormonal levels was then appraised in Caucasians using specific and sensitive mass spectrometry-based methods. After adjusting for known risk factors, variants of CYP17A1 (rs6162), HSD17B2 (rs4243229 and rs7201637), and ESR1 (rs1062577) were associated with progressive disease in both cohorts. Indeed, the presence of these variations was significantly associated with progression in Caucasians (HR, 2.29-4.10; P = 0.0014-2 × 10(-7)) and survival in Taiwanese patients [HR = 3.74; 95% confidence interval (CI): 1.71-8.19, P = 0.009]. Remarkably, the CYP17A1 rs6162 polymorphism was linked to plasma dehydroepiandrosterone-sulfate (DHEA-S) levels (P = 0.03), HSD17B2 rs7201637 with levels of dihydrotestosterone (P = 0.03), and ESR1 rs1062577 with levels of estrone-S and androsterone-glucuronide (P ≤ 0.05). This study identifies, in different ethnic groups and at different disease stages, CYP17A1, HSD17B2, and ESR1 as attractive prognostic molecular markers of prostate cancer progression. Show less

Essential tremor (ET), which is one of the most common movement disorders, may lead to severe interference in quality of life. The first genome-wide association study (GWAS) has identified an association of the LINGO1 variant (rs9652490) with ET in Americans and Europeans. Recently, a second GWAS that was performed in a European population has discovered a new variant (rs3794087) of the main glial glutamate transporter (SLC1A2) that increases the risk of ET with an odds ratio of about 1.4. SLC1A2 encodes for the major glial high-affinity glutamate reuptake transporter in the brain and is a potential ET susceptibility gene. Because replication in a different ethnic population is important for validating a finding, we conducted a case-control study to investigate the SLC1A2 variant in an Asian cohort with ET in Taiwan. A total of 542 subjects (273 ET patients and 269 controls) were included. The results showed that rs3794087 was associated with ET among the Taiwanese. The odds ratio was 1.37. Our results were similar to those of the second GWAS of ET in Europeans, and this confirms that SLC1A2 may be a good functional candidate gene for ET. A replication study in another independent population is of importance to validate this association. Show less

LINGO-1 is a functional component of the Nogo receptor 1 · p75(NTR) · LINGO-1 and Nogo receptor 1 · TAJ (TNFRSF19/TROY)·LINGO-1 signaling complexes. It has recently been shown that LINGO-1 antagonists significantly improve neuronal survival after neural injury. However, the mechanism by which LINGO-1 signaling influences susceptibility to apoptosis remains unknown. In an effort to better understand how LINGO-1 regulates these signaling pathways, we used an established model of serum deprivation (SD) to induce neuronal apoptosis. We demonstrate that treatment either with a construct containing the intracellular domain of LINGO-1 or with Nogo66, a LINGO-1 receptor complex agonist, resulted in an enhanced rate of apoptosis in primary cultured cortical neurons under SD. Reducing the expression levels of the serine/threonine kinase WNK3 using shRNA or inhibiting its kinase activity had similar effects on the survival of serum-deprived neurons. Consistent with these observations, we found that LINGO-1 and WNK3 co-localized and co-precipitated in cultured cortical neurons and brain tissue. Significantly, this co-association was enhanced by Nogo66 treatment. Binding of WNK3 to the intracellular domain of LINGO-1 led to a reduction in WNK3 kinase activity, as did Nogo66 stimulation. Moreover, in vitro and in vivo evidence indicates that endogenous WNK3 suppresses SD-induced neuronal apoptosis in a kinase-dependent manner, as the expression of either a WNK3 RNAi construct or a kinase-dead N-terminal fragment of WNK3 led to increased apoptosis. Taken together, our results show that LINGO-1 potentiates neuronal apoptosis, likely by inhibiting WNK3 kinase activity. Show less

Human complex metabolic traits are in part regulated by genetic determinants. Here we applied exome sequencing to identify novel associations of coding polymorphisms at minor allele frequencies (MAFs) >1% with common metabolic phenotypes. The study comprised three stages. We performed medium-depth (8×) whole exome sequencing in 1,000 cases with type 2 diabetes, BMI >27.5 kg/m(2) and hypertension and in 1,000 controls (stage 1). We selected 16,192 polymorphisms nominally associated (p < 0.05) with case-control status, from four selected annotation categories or from loci reported to associate with metabolic traits. These variants were genotyped in 15,989 Danes to search for association with 12 metabolic phenotypes (stage 2). In stage 3, polymorphisms showing potential associations were genotyped in a further 63,896 Europeans. Exome sequencing identified 70,182 polymorphisms with MAF >1%. In stage 2 we identified 51 potential associations with one or more of eight metabolic phenotypes covered by 45 unique polymorphisms. In meta-analyses of stage 2 and stage 3 results, we demonstrated robust associations for coding polymorphisms in CD300LG (fasting HDL-cholesterol: MAF 3.5%, p = 8.5 × 10(-14)), COBLL1 (type 2 diabetes: MAF 12.5%, OR 0.88, p = 1.2 × 10(-11)) and MACF1 (type 2 diabetes: MAF 23.4%, OR 1.10, p = 8.2 × 10(-10)). We applied exome sequencing as a basis for finding genetic determinants of metabolic traits and show the existence of low-frequency and common coding polymorphisms with impact on common metabolic traits. Based on our study, coding polymorphisms with MAF above 1% do not seem to have particularly high effect sizes on the measured metabolic traits. Show less

We aimed to investigate the effects of LXRα, ChREBP and Elovl6 in the development of insulin resistance-induced by medium- and long-chain fatty acids. Sprague Dawley rats were fed a standard chow diet (Control group) or a high-fat, high sucrose diet with different fat sources (coconut oil, lard, sunflower and fish oil) for 8 weeks. These oils were rich in medium-chain saturated fatty acids (MCFA group), long-chain saturated fatty acids (LCFA group), n-6 and n-3 long-chain polyunsaturated fatty acids (n-6 PUFA and n-3 PUFA groups), respectively, which had different chain lengths and degrees of unsaturation. Hyperinsulinemic-euglycemic clamp with [6-(3)H] glucose infusion was performed in conscious rats to assess hepatic insulin sensitivity. LCFA and n-6 PUFA groups induced hepatic insulin resistance and increased liver X receptor α (LXRα), carbohydrate response element binding protein (ChREBP) and long-chain fatty acid elongase 6 (Elovl6) expression in liver and white adipose tissue (WAT). Furthermore, LCFA and n-6 PUFA groups suppressed Akt serine 473 phosphorylation in liver and WAT. By contrast, in liver and WAT, MCFA and n-3 PUFA groups decreased LXRα, ChREBP and Elovl6 expression and improved insulin signaling and insulin resistance, but Akt serine 473 phosphorylation was not restored by MCFA group in WAT. This study demonstrated that the mechanism of the different effects of medium- and long-chain fatty acids on hepatic insulin resistance involves LXRα, ChREBP and Elovl6 alternations in liver and WAT. It points to a new strategy for ameliorating insulin resistance and diabetes through intervention on Elovl6 or its control genes. Show less

Alzheimer's disease (AD) is associated with impaired Aβ degradation in the brain. Enhancing the process of Aβ clearance is an attractive potential AD therapy. Treatment with LXR agonists may reduce Aβ levels in vivo. However, the clinical potential of many LXR agonists is limited because of their nonselective actions on LXRα/β, which lead to undesired hepatic lipogenesis via LXRα-dependent pathways. In this study, ABCA1 up-regulators were identified from a series of flavonoids and were found to preferentially activate LXRβ and up-regulate expression of ABCA1 and apoE in different cell lines. Further investigations confirmed that these compounds facilitate intracellular Aβ clearance in Aβ-loaded BV2 cells. Administration of compound 19 reduced total brain Aβ and plaque burden in APP/PS1 double transgenic mice, associated with elevated ABCA1 and apoE expression. Compared with the nonselective LXR agonists, the active compounds reported here induced less accumulation of undesired lipids and triglycerides in HepG2 cells. Show less

Atherosclerosis is a chronic immunoinflammatory disease associated with blood lipid disorders. Previous studies in mice have demonstrated that liver X receptor (LXR)‑ATP‑binding cassette (ABC) A1/ABCG1/C‑C chemokine receptor type 7 (CCR7) and nuclear factor κB (NF‑κB) signaling pathways are important for atherosclerotic plaque formation. In addition, Sirtuin 1 (SIRT1) has been reported as a key regulator in the protection from risk of atherosclerosis. However, the exact mechanism by which SIRT1 prevents atherosclerosis remains largely unknown. To explore the possible mechanisms, the expression of SIRT1 and the association between SIRT1, LXR and NF‑κB in the process of foam cell formation was investigated in an in vitro human mononuclear U937 cell line. Monocyte‑derived foam cells were induced by palmitate and Ox‑LDL treatment. Oil Red O staining revealed an accumulation of a large number of lipid droplets in foam cells. Results of reverse transcription polymerase chain reaction (RT-PCR) revealed that SIRT1 expression was downregulated during foam cell formation. In addition, the expression of LXRα and its targets, ABCA1, ABCG1 and CCR7, were downregulated. However, NF‑κB and its targets, tumor necrosis factor α (TNFα) and interleukin (IL)‑1β, were upregulated in foam cells. Following activation of SIRT1 by SRT1720, the expression of LXRα and its targets increased, whereas expression of NF‑κB and its targets decreased. Furthermore, the formation of foam cells was blocked. The SIRT1 inhibitor, nicotinamide, was found to eliminate the effects of SRT1720. Results of the present study indicate that SIRT1 may prevent the formation and progression of atherosclerosis by enhancing the LXR‑ABCA1/ABCG1/CCR7 and inhibiting the NF‑κB pathways. Show less

The anaphase-promoting complex (APC) is an E3 ubiquitin ligase which controls ubiquitination and degradation of multiple cell cycle regulatory proteins. During infection, human cytomegalovirus (HCMV), a widespread pathogen, not only phosphorylates the APC coactivator Cdh1 via the multifunctional viral kinase pUL97, it also promotes degradation of APC subunits via an unknown mechanism. Using a proteomics approach, we found that a recently identified HCMV protein, pUL21a, interacted with the APC. Importantly, we determined that expression of pUL21a was necessary and sufficient for proteasome-dependent degradation of APC subunits APC4 and APC5. This resulted in APC disruption and required pUL21a binding to the APC. We have identified the proline-arginine amino acid pair at residues 109-110 in pUL21a to be critical for its ability to bind and regulate the APC. A point mutant virus in which proline-arginine were mutated to alanines (PR-AA) grew at wild-type levels. However, a double mutant virus in which the viral ability to regulate the APC was abrogated by both PR-AA point mutation and UL97 deletion was markedly more attenuated compared to the UL97 deletion virus alone. This suggests that these mutations are synthetically lethal, and that HCMV exploits two viral factors to ensure successful disruption of the APC to overcome its restriction on virus infection. This study reveals the HCMV protein pUL21a as a novel APC regulator and uncovers a unique viral mechanism to subvert APC activity. Show less

Clinically, elevated cancer antigen 125 (CA-125) in blood predicts tumor burden in a woman's body, especially in the ovary, but cannot differentiate between malignant or benign. We here used intensive modern proteomic approaches to identify predictive proteins in the serum of women with elevated CA-125 to differentiate malignant from benign ovarian tumors. We identified differentially expressed proteins in serum samples of ovarian cancer (OC) patients, benign ovarian tumor (BT) patients, and healthy control women using mass spectrometry-based quantitative proteomics. Both the OC and BT patients had elevated CA-125. Quantitation was achieved using isobaric tags for relative and absolute quantitation. We obtained 124 quantified differential serum proteins in OC compared with BT. Two proteins, apolipoprotein A-4 (APOA4) and natural resistance-associated macrophage 1, were verified using Western blotting. Proteome profiling applied to OC cases identified several differential serum proteins in the serum of women with elevated CA-125. A novel protein, APOA4, has the potential to be a marker for malignant tumor differentiation in the serum of women with elevated CA-125. Show less

Hemodialysis (HD) patients are under recurrent circulatory stress, and hemodialysis has a high mortality rate. The characteristics of plasma proteomes in patients surviving long-term HD remain obscure, as well as the potential biomarkers in predicting prognoses. This study reports the proteome analyses of patient plasma from non-diabetic long-term HD (LHD, dialysis vintage 14.9±4.1 years, n = 6) and the age/sex/uremic etiology-comparable short-term HD (SHD, dialysis vintage 5.3±2.9 years, n = 6) using 2-DE and mass spectrometry. In addition, a 4-year longitudinal follow-up of 60 non-diabetic HD patients was subsequently conducted to analyze the baseline plasma proteins by ELISA in predicting prognosis. Compared to the SHD, the LHD survivors had increased plasma vitamin D binding proteins (DBP) and decreased clusterin, apolipoprotein A-IV, haptoglobin, hemopexin, complement factors B and H, and altered isoforms of α1-antitrypsin and fibrinogen gamma. During the 45.7±15 months for follow-up of the 60 HD patient cases, 16 patients died. Kaplan-Meier analysis demonstrated that HD patients with the lowest tertile of the baseline plasma DBP level have a significantly higher mortality rate. Multivariate Cox regression analysis further indicated that DBP is an independent predictor of mortality. In summary, the altered plasma proteins in LHD implicated accelerated atherosclerosis, defective antioxidative activity, increased inflammation/infection, and organ dysfunction. Furthermore, lower baseline plasma DBP in HD patients is related to mortality. The results suggest that the proteomic approach could help discover the potential biomarker in HD prognoses. Show less

Apolipoprotein A5 (apoA5), an important determinant of plasma triglyceride (TG) levels, has been recently reported to modulate TG metabolism in hepatocytes. In this study, we investigated whether apoA5 can be internalized by adipocytes and regulate cellular TG storage. Human preadipocytes, derived from subcutaneous adipose tissue of patients undergoing abdominal surgery, were differentiated into mature adipocytes. Pulse-chase experiments revealed that apoA5 was internalized into human adipocytes, and ∼70% of the apoA5 internalized during the pulse remained intracellular within a 24-h chase, while 30% was degraded. Preincubation with heparin and the receptor-associated protein, both of which prevented the apoA5 interaction with members of the low-density lipoprotein receptor gene family, markedly reduced the uptake of apoA5 by 61% and 52%, respectively, which were subsequently confirmed by Western blot analysis. Using confocal microscopy, we demonstrated that labeled apoA5 surrounded lipid droplets in human adipocytes and colocalized with the known lipid droplet protein perilipin. Importantly, treatment of adipocytes with apoA5 significantly decreased cellular TG storage. In conclusion, apoA5 can be internalized by human adipocytes and may act as a novel regulator to control TG storage in human adipocytes. Show less

Apolipoprotein A5 (APOA5) was identified as a strong modulator of serum lipids. Moreover, an APOA5 gene -1131T>C polymorphism has been associated with serum lipids, but the results are inconsistent according to ethnic and racial groups. We have genotyped and analyzed 1,619 outpatients of Korean oriental medicine hospitals who were classified into three Sasang constitution groups (SCGs), So-Yang (SY), So-Eum (SE), and Tae-Eum (TE). There were no significant difference in the distribution of the APOA5 -1131T>C genotype among the three SCGs. Subjects with the C allele in SY and TE showed significantly lower serum high-density lipoprotein cholesterol (HDL-C) and higher triglyceride (TG) levels than noncarriers of the C allele. These results show the differences in the prevalence of decreasing serum HDL-C and elevating serum TG levels along with APOA5 -1131T>C polymorphism according to SCG and suggest that SCG may act as a significant risk factor for hypo-HDL-C-emia and hypertriglyceridemia susceptibility. Show less

Histone deacetylase (HDAC) plays an important role in the deacetylation of histone, which can alter gene expression patterns and affect cell behavior associated with malignant transformation. The aims of this study were to investigate the relationships between HDAC1, HDAC2, clinicopathologic characteristics, patient prognosis and apoptosis, to clarify the mechanism of upregulation of the Axis inhibitor Axin (an important regulator of the Wnt pathway) by X-radiation and to elucidate the effect of siRNA on radiation therapy of non-small cell lung cancer (NSCLC). HDAC1 and HDAC2 expression levels were measured by immunohistochemistry and reverse transcription PCR. Apoptosis was determined by terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling and fluorescence activated cell sorting. BE1 cells expressing Axin were exposed to 2 Gy of X-radiation. Expression of HDAC1 and that of HDAC2 were correlated, and significantly higher in NSCLC tissues than in normal lung tissues (P < 0.05). HDAC1 and HDAC2 expression was correlated with pTNM stage and negatively correlated with differentiation of NSCLC and apoptotic index (P < 0.05). The prognosis of patients with low expression of HDAC1 and HDAC2 was better than that of those with high expression. X-radiation and siRNA inhibited HDAC1 and HDAC2 expression in NSCLC cells and Axin levels were significantly higher in BE1 cells. X-radiation and siRNA inhibit expression of HDAC1 and HDAC2, weaken the inhibitory effect of HDAC on Axin, upregulate Axin expression and induce apoptosis of lung cancer cells. Inhibition of HDAC1 and HDAC2 is a means of enhancing the radiosensitivity of NSCLC. Show less

The pleiotropic features of obesity, retinal degeneration, polydactyly, kidney abnormalities, cognitive impairment, hypertension, and diabetes found in Bardet-Biedl syndrome (BBS) make this disorder an important model disorder for identifying molecular mechanisms involved in common human diseases. To date, 16 BBS genes have been reported, seven of which (BBS1, 2, 4, 5, 7, 8, and 9) code for proteins that form a complex known as the BBSome. The function of the BBSome involves ciliary membrane biogenesis. Three additional BBS genes (BBS6, BBS10, and BBS12) have homology to type II chaperonins and interact with CCT/TRiC proteins and BBS7 to form a complex termed the BBS-chaperonin complex. This complex is required for BBSome assembly. Little is known about the process and the regulation of BBSome formation. We utilized point mutations and null alleles of BBS proteins to disrupt assembly of the BBSome leading to the accumulation of BBSome assembly intermediates. By characterizing BBSome assembly intermediates, we show that the BBS-chaperonin complex plays a role in BBS7 stability. BBS7 interacts with BBS2 and becomes part of a BBS7-BBS2-BBS9 assembly intermediate referred to as the BBSome core complex because it forms the core of the BBSome. BBS1, BBS5, BBS8, and finally BBS4 are added to the BBSome core to form the complete BBSome. Show less

We had previously identified the mutant allele of apm1(+) that encodes a homolog of the mammalian μ 1A subunit of the clathrin-associated adaptor protein-1 (AP-1) complex and demonstrated that the AP-1 complex plays a role in Golgi/endosome trafficking, secretion, and vacuole fusion in fission yeast. Here, we isolated a mutant allele of its4(+)/sip1(+), which encodes a conserved AP-1 accessory protein. The its4-1/sip1-i4 mutants and apm1-deletion cells exhibited similar phenotypes, including sensitivity to the calcineurin inhibitor FK506, Cl(-) and valproic acid as well as various defects in Golgi/endosomal trafficking and cytokinesis. Electron micrographs of sip1-i4 mutants revealed vacuole fragmentation and accumulation of abnormal Golgi-like structures and secretory vesicles. Overexpression of Apm1 suppressed defective membrane trafficking in sip1-i4 mutants. The Sip1-green fluorescent protein (GFP) co-localized with Apm1-mCherry at Golgi/endosomes, and Sip1 physically interacted with each subunit of the AP-1 complex. We found that Sip1 was a Golgi/endosomal protein and the sip1-i4 mutation affected AP-1 localization at Golgi/endosomes, thus indicating that Sip1 recruited the AP-1 complex to endosomal membranes by physically interacting with each subunit of this complex. Furthermore, Sip1 is required for the correct localization of Bgs1/Cps1, 1,3-β-D-glucan synthase to polarized growth sites. Consistently, the sip1-i4 mutants displayed a severe sensitivity to micafungin, a potent inhibitor of 1,3-β-D-glucan synthase. Taken together, our findings reveal a role for Sip1 in the regulation of Golgi/endosome trafficking in coordination with the AP-1 complex, and identified Bgs1, required for cell wall synthesis, as the new cargo of AP-1-dependent trafficking. Show less

The ability of the human immune system to respond to vaccination declines with age. We identified an age-associated defect in T cell receptor (TCR)-induced extracellular signal-regulated kinase (ERK) phosphorylation in naive CD4(+) T cells, whereas other signals, such as ζ chain-associated protein kinase 70 (ZAP70) and phospholipase C-γ1 phosphorylation, were not impaired. The defective ERK signaling was caused by the dual specific phosphatase 6 (DUSP6), whose protein expression increased with age due to a decline in repression by miR-181a. Reconstitution of miR-181a lowered DUSP6 expression in naive CD4(+) T cells in elderly individuals. DUSP6 repression using miR-181a or specific siRNA and DUSP6 inhibition by the allosteric inhibitor (E)-2-benzylidene-3-(cyclohexylamino)-2,3-dihydro-1H-inden-1-one improved CD4(+) T cell responses, as seen by increased expression of activation markers, improved proliferation and supported preferential T helper type 1 cell differentiation. DUSP6 is a potential intervention target for restoring T cell responses in the elderly, which may augment the effectiveness of vaccination. Show less