👤 Ziqi Zhao

Bisphenol A (BPA) is a potential endocrine disruptor. It has been shown that it reduces serum testosterone level in rodents after exposure. However, the mechanism is unclear. The object of the present study is to investigate the effects of BPA on human and rat steroidogenic enzymes including P450 17α-hydroxylase/17,20-lyase (CYP17A1), 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-hydroxysteroid dehydrogenase 3 (17β-HSD3). Human and rat testis microsomes were exposed to various concentrations of BPA (10(-8)-10(-4)M). BPA inhibited human and rat 3β-HSD, CYP17A1 and 17β-HSD3 activities. The half maximal inhibitory concentrations (IC(50)s) of BPA for human and rat testis 3β-HSD were 7.92±1.03 and 26.49±3.03 μM (200 μM pregnenolone), respectively. The IC(50)s for human and rat CYP17A1 (1 μM progesterone) were 18.99±3.75 and 64.67±4.04 μM, respectively. BPA was a weak HSD17B3 inhibitor with IC(50)s of about 100 μM (200 nM androstenedione). BPA also concentration-dependently inhibited testosterone production by rat Leydig cells. In conclusion, BPA is an inhibitor for 3β-HSD, CYP17A1 and 17β-HSD3. Human 3β-HSD and CYP17A1 are more sensitive to BPA than rat 3β-HSD and CYP17A1. Show less

Human and rat testis microsomes were used to investigate direct inhibitory activities of methoxychlor (MXC) and its metabolite 2,2-bis(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE) on 3β-hydroxysteroid dehydrogenase (3β-HSD) and 17β-hydroxysteroid dehydrogenase type 3 (17β-HSD3). The 3β-HSD and 17β-HSD3 enzymes are involved in the reactions that culminate in androgen biosynthesis in Leydig cells. The results demonstrated that MXC and HPTE inhibited human 3β-HSD activity at a concentration of 10 nm. The half maximal inhibitory concentration (IC(50) ) for MXC inhibition of 3β-HSD was 53.21 ± 15.52 μm (human) and 46.15 ± 17.94 μm (rat), and for HPTE, it was 8.29 ± 2.49 μm (human) and 13.82 ± 2.26 μm (rat). At the higher concentration of 100 μm, MXC did not affect human and rat 17β-HSD3 activity. However, the IC(50) for HPTE inhibition of 17β-HSD3 was 12.1 ± 1.9 μm (human) and 32 .0 ± 8.6 μm (rat). The mode of action of MXC and HPTE on 3β-HSD activity was non-competitive with the substrate pregnenolone, but was competitive with the cofactor NAD(+) . The mode of HPTE inhibition of 17β-HSD3 was non-competitive with the substrate androstenedione, but was competitive with the cofactor NADPH. In summary, our results showed that HPTE, which is the biologically active metabolite of MXC, has the capacity for direct inhibition of 3β-HSD and 17β-HSD3 enzyme activity. Inhibition of enzyme activity is presumably associated with suppression of steroidogenesis in gonadal tissues and has implications for testis function. Show less

Obesity is a serious health concern for children and adolescents, particularly in Western societies, where its incidence is now considered to have reached epidemic proportions. A number of genetic determinants of adult BMI have already been established through genome wide association studies (GWAS), most recently from the GIANT meta-analysis of such datasets combined. In this current study of European Americans, we examined the 32 loci detected in that GIANT study in the context of common childhood obesity within a cohort of 1,097 cases (defined as BMI ≥95th percentile), together with 2,760 lean controls (defined as BMI <50th percentile), aged between 2 and 18 years old. Nine of these single-nucleotide polymorphims (SNPs) yielded at least nominal evidence for association with common childhood obesity, namely at the FTO, TMEM18, NRXN3, MC4R, SEC16B, GNPDA2, TNNI3K, QPCTL, and BDNF loci. However, overall 28 of the 32 loci showed directionally consistent effects to that of the adult BMI meta-analysis. We conclude that among the 32 loci that have been reported to associate with adult BMI in the largest meta-analysis of BMI to date, at least nine also contribute to the determination of common obesity in childhood in European Americans, as demonstrated by their associations in our pediatric cohort. Show less

Large-scale genome-wide association studies (GWAS) have identified many loci associated with body mass index (BMI), but few studies focused on obesity as a binary trait. Here we report the results of a GWAS and candidate SNP genotyping study of obesity, including extremely obese cases and never overweight controls as well as families segregating extreme obesity and thinness. We first performed a GWAS on 520 cases (BMI>35 kg/m(2)) and 540 control subjects (BMI<25 kg/m(2)), on measures of obesity and obesity-related traits. We subsequently followed up obesity-associated signals by genotyping the top ∼500 SNPs from GWAS in the combined sample of cases, controls and family members totaling 2,256 individuals. For the binary trait of obesity, we found 16 genome-wide significant signals within the FTO gene (strongest signal at rs17817449, P = 2.5 × 10(-12)). We next examined obesity-related quantitative traits (such as total body weight, waist circumference and waist to hip ratio), and detected genome-wide significant signals between waist to hip ratio and NRXN3 (rs11624704, P = 2.67 × 10(-9)), previously associated with body weight and fat distribution. Our study demonstrated how a relatively small sample ascertained through extreme phenotypes can detect genuine associations in a GWAS. Show less

Obesity is globally prevalent and highly heritable, but its underlying genetic factors remain largely elusive. To identify genetic loci for obesity susceptibility, we examined associations between body mass index and ∼ 2.8 million SNPs in up to 123,865 individuals with targeted follow up of 42 SNPs in up to 125,931 additional individuals. We confirmed 14 known obesity susceptibility loci and identified 18 new loci associated with body mass index (P < 5 × 10⁻⁸), one of which includes a copy number variant near GPRC5B. Some loci (at MC4R, POMC, SH2B1 and BDNF) map near key hypothalamic regulators of energy balance, and one of these loci is near GIPR, an incretin receptor. Furthermore, genes in other newly associated loci may provide new insights into human body weight regulation. Show less

Glucose levels 2 h after an oral glucose challenge are a clinical measure of glucose tolerance used in the diagnosis of type 2 diabetes. We report a meta-analysis of nine genome-wide association studies (n = 15,234 nondiabetic individuals) and a follow-up of 29 independent loci (n = 6,958-30,620). We identify variants at the GIPR locus associated with 2-h glucose level (rs10423928, beta (s.e.m.) = 0.09 (0.01) mmol/l per A allele, P = 2.0 x 10(-15)). The GIPR A-allele carriers also showed decreased insulin secretion (n = 22,492; insulinogenic index, P = 1.0 x 10(-17); ratio of insulin to glucose area under the curve, P = 1.3 x 10(-16)) and diminished incretin effect (n = 804; P = 4.3 x 10(-4)). We also identified variants at ADCY5 (rs2877716, P = 4.2 x 10(-16)), VPS13C (rs17271305, P = 4.1 x 10(-8)), GCKR (rs1260326, P = 7.1 x 10(-11)) and TCF7L2 (rs7903146, P = 4.2 x 10(-10)) associated with 2-h glucose. Of the three newly implicated loci (GIPR, ADCY5 and VPS13C), only ADCY5 was found to be associated with type 2 diabetes in collaborating studies (n = 35,869 cases, 89,798 controls, OR = 1.12, 95% CI 1.09-1.15, P = 4.8 x 10(-18)). Show less

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation at the synovial membrane. Although great progress has been made recently in exploring the etiology and pathogenesis of RA, its molecular pathological mechanism remains to be further defined and it is still a great challenge in determining the diagnosis and in choosing the appropriate therapy in early patients. This study was performed to screen candidate RA-associated serum proteins by comparative proteomics to provide research clues to early diagnosis and treatment of RA. Sera isolated from 6 RA patients and 6 healthy volunteers were pooled respectively and high-abundance proteins were depleted by Plasma 7 Multiple Affinity Removal System. The protein expression profiles between the two groups were then compared by two-dimensional gel electrophoresis (2-DE) and the proteins over/under-expressed by more than 3-fold were identified by mass spectrometry analysis. To validate the differential expression levels of the identified proteins between the two groups, ELISA was performed in two of the identified proteins in individual sera from 32 RA patients and 32 volunteers. Eight proteins which over/under-expressed in sera of RA patients were identified. Among them, chain A of transthyretin (TTR) was under-expressed, while serum amyloid A protein, apolipoprotein A (ApoA)-IV, ApoA-IV precursor, haptoglobin 2, ceruloplasmin (Cp), immunoglobulin superfamily 22 and HT016 were over-expressed. ELISA test confirmed that Cp expressed remarkably higher while TTR obviously lower in RA group compared with volunteer group. There were 8 identified proteins differentially expressed between RA group and volunteer group, which might be candidate RA-associated proteins and might be promising diagnostic indicators or therapeutic targets for RA. Show less

to explore the potential role of apolipoprotein A5 (apoA5) on the hypertriglyceridemia (HTG)-lowering effects of statin. twenty-four Sprague-Dawley rats were randomized into 3 groups: (1) control group (n = 8), with no special treatment; (2) HTG group (n = 8), treated with 10% fructose water for 6 weeks; (3) statin group (n = 8), treated with 10% fructose water for 2 weeks and cotreated with atorvastatin 10 mg×kg(-1)×d(-1) for another 4 weeks. Body weight, fasting plasma lipids and the hepatic expressions of apoA5 and peroxisome proliferator activated receptor (PPAR)α were determined. In separate in vitro experiments, we tested the effects of atorvastatin on TG and the expressions of apoA5 and PPARα in HepG2 cells. (1) at 6 weeks, plasma TG was higher in rats in HTG group than in controls, which was significantly reduced in statin group (both P < 0.05). (2) Rat hepatic apoA5 expression in HTG group was significantly lower than in control group and was significantly higher in statin group than in HTG group (both P < 0.05). (3) Similarly, rat PPARα mRNA expression in HTG group was lower than in control group and was higher in statin group than in HTG group (both P < 0.05). (4) Statin significantly upregulated the expressions of apoA5 and PPARα and decreased TG in HepG2 cells. The above effects induced by statin was blocked in the presence of PPARα inhibitor. upregulation of apoA5 expression contributes to TG lowering effect of statin via PPARα signaling pathway. Show less

Genetic studies might provide new insights into the biological mechanisms underlying lipid metabolism and risk of CAD. We therefore conducted a genome-wide association study to identify novel genetic determinants of low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglycerides. We combined genome-wide association data from 8 studies, comprising up to 17 723 participants with information on circulating lipid concentrations. We did independent replication studies in up to 37 774 participants from 8 populations and also in a population of Indian Asian descent. We also assessed the association between single-nucleotide polymorphisms (SNPs) at lipid loci and risk of CAD in up to 9 633 cases and 38 684 controls. We identified 4 novel genetic loci that showed reproducible associations with lipids (probability values, 1.6×10(-8) to 3.1×10(-10)). These include a potentially functional SNP in the SLC39A8 gene for HDL-C, an SNP near the MYLIP/GMPR and PPP1R3B genes for LDL-C, and at the AFF1 gene for triglycerides. SNPs showing strong statistical association with 1 or more lipid traits at the CELSR2, APOB, APOE-C1-C4-C2 cluster, LPL, ZNF259-APOA5-A4-C3-A1 cluster and TRIB1 loci were also associated with CAD risk (probability values, 1.1×10(-3) to 1.2×10(-9)). We have identified 4 novel loci associated with circulating lipids. We also show that in addition to those that are largely associated with LDL-C, genetic loci mainly associated with circulating triglycerides and HDL-C are also associated with risk of CAD. These findings potentially provide new insights into the biological mechanisms underlying lipid metabolism and CAD risk. Show less

Studies examining the association of apolipoprotein A5 (APOA5) gene -1131 T>C polymorphism with blood lipids produced inconsistent results. In this meta-analysis encompassing all the relevant studies, we aimed to investigate the association of the -1131 T>C polymorphism with fasting blood lipids. We limited our analysis to the following four blood lipid variables: total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C). Subjects were confined to adults who were at least 18 years old. A dominant model was used for this meta-analysis. 37 studies with 37859 subjects were included in this meta-analysis. The results showed that the carriers of -1131C allele have higher blood TC and TG than the non-carriers: standardized mean difference (SMD) = 0.08, 95% confidence interval (CI, 0.05, 0.11), P < 0.00001, P(heterogeneity) = 0.42, and SMD = 0.31, 95% CI (0.27, 0.34), P < 0.00001, P(heterogeneity) = 0.0003, respectively. Significant association between the -1131 T>C polymorphism and lower blood HDL-C was also detected under the dominant model: SMD = -0.17, 95% CI (-0.21, -0.14), P < 0.00001, P(heterogeneity) = 0.003. Our meta-analysis supports the strong association of the APOA5 -1131 T>C polymorphism with higher levels of TC and TG, and lower levels of HDL-C. Show less

Hypertriglyceridemia is associated insulin resistance in obese people. Recently identified apolipoprotein A5 (apoA5) is involved in triglyceride (TG) metabolism. This study was to investigate the role of apoA5 in insulin resistance-related hypertriglyceridemia in obesity. 682 participants including 340 non-obese individuals and 342 obese individuals were recruited in this study. Plasma apoA5 levels were measured. The insulin resistance in participants was assessed by homeostasis model assessment of insulin resistance (HOMA-IR). An insulin resistant and hypertriglyceridemic rat model was established by high-fructose diet with obese Zucker rats as positive controls. Besides, two insulin resistant models in vitro were induced by insulin and tumor necrosis factor-alpha (TNFalpha) in HepG2 cells. Obese participants had lower plasma apoA5 levels. Plasma apoA5 levels were inversely correlated with TG, body mass index and HOMA-IR in humans. Furthermore, hepatic and plasma apoA5 reduced in fructose-fed rats whereas no significant changes of apoA5 were observed in obese Zucker rats. In addition, treatment of HepG2 cells with insulin and TNFalpha decreased apoA5 expression and increased TG content. Thus, decreased apolipoprotein A5 is implicated in insulin resistance-related hypertriglyceridemia in obesity. Show less

We have shown that expression of apolipoprotein (apo) C-III promotes VLDL secretion from transfected McA-RH7777 cells under lipid-rich conditions. To determine structural elements within apoC-III that confer to this function, we contrasted wild-type apoC-III with a mutant Ala23Thr originally identified in hypotriglyceridemia subjects. Although synthesis of [(3)H]glycerol-labeled TAG was comparable between cells expressing wild-type apoC-III (C3wt cells) or Ala23Thr mutant (C3AT cells), secretion of [(3)H]TAG from C3AT cells was markedly decreased. The lowered [(3)H]TAG secretion was associated with an inability of C3AT cells to assemble VLDL(1). Moreover, [(3)H]TAG within the microsomal lumen in C3AT cells was 60% higher than that in C3wt cells, yet the activity of microsomal triglyceride-transfer protein in C3AT cells was not elevated. The accumulated [(3)H]TAG in C3AT microsomal lumen was mainly associated with lumenal IDL/LDL-like lipoproteins. Phenotypically, this [(3)H]TAG fractionation profiling resembled what was observed in cells treated with brefeldin A, which at low dose specifically blocked the second-step VLDL(1) maturation. Furthermore, lumenal [(35)S]Ala23Thr protein accumulated in IDL/LDL fractions and was absent in VLDL fractions in C3AT cells. These results suggest that the presence of Ala23Thr protein in lumenal IDL/LDL particles might prevent effective fusion between lipid droplets and VLDL precursors. Thus, the current study reveals an important structural element residing within the N-terminal region of apoC-III that governs the second step VLDL(1) maturation. Show less

It has been reported that N-methyl-D-aspartate receptor (NMDAR)-triggered neurotoxicity is related to excessive Ca(2+) loading and an increase in nitric oxide (NO) concentration. However, the molecular mechanisms that underlie these events are not completely understood. NMDARs and neuronal NO synthase each binds to the scaffolding protein postsynaptic density (PSD)-93 through its PDZ domains. In this study, we determined whether PSD-93 plays a critical role in NMDAR/Ca(2+)/NO-mediated neurotoxicity. We found that the targeted disruption of the PSD-93 gene attenuated the neurotoxicity triggered by NMDAR activation, but not by non-NMDAR activation, in cultured mouse cortical neurons. PSD-93 deficiency reduced the amount of NMDAR subunits NR2A and NR2B in synaptosomal fractions from the cortical neurons and significantly prevented NMDA-stimulated increases in cyclic guanosine 3',5'-monophosphate and Ca(2+) loading in the cortical neurons. These findings indicate that PSD-93 deficiency could block NMDAR-triggered neurotoxicity by disrupting the NMDAR-Ca(2+)-NO signaling pathway and reducing expression of synaptic NR2A and NR2B. Since NMDARs, Ca(2+), and NO play a critical role during the development of brain trauma, seizures, and ischemia, the present work suggests that PSD-93 might contribute to molecular mechanisms of neuronal damage in these brain disorders. Show less

Levels of circulating glucose are tightly regulated. To identify new loci influencing glycemic traits, we performed meta-analyses of 21 genome-wide association studies informative for fasting glucose, fasting insulin and indices of beta-cell function (HOMA-B) and insulin resistance (HOMA-IR) in up to 46,186 nondiabetic participants. Follow-up of 25 loci in up to 76,558 additional subjects identified 16 loci associated with fasting glucose and HOMA-B and two loci associated with fasting insulin and HOMA-IR. These include nine loci newly associated with fasting glucose (in or near ADCY5, MADD, ADRA2A, CRY2, FADS1, GLIS3, SLC2A2, PROX1 and C2CD4B) and one influencing fasting insulin and HOMA-IR (near IGF1). We also demonstrated association of ADCY5, PROX1, GCK, GCKR and DGKB-TMEM195 with type 2 diabetes. Within these loci, likely biological candidate genes influence signal transduction, cell proliferation, development, glucose-sensing and circadian regulation. Our results demonstrate that genetic studies of glycemic traits can identify type 2 diabetes risk loci, as well as loci containing gene variants that are associated with a modest elevation in glucose levels but are not associated with overt diabetes. Show less

Perfluorooctane acid (PFOA) is classified as a persistent organic pollutant and as an endocrine disruptor. The mechanism by which PFOA causes reduced testosterone production in males is not known. We tested our hypothesis that PFOA interferes with Leydig cell steroidogenic enzymes by measuring its effect on 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17beta-hydroxysteroid dehydrogenase 3 (17beta-HSD3) activities in rat testis microsomes and Leydig cells. The IC(50)s of PFOA and mode of inhibition were assayed. PFOA inhibited microsomal 3beta-HSD with an IC(50) of 53.2+/-25.9 microM and 17beta-HSD3 with an IC(50) 17.7+/-6.8 microM. PFOA inhibited intact Leydig cell 3beta-HSD with an IC(50) of 146.1+/-0.9 microM and 17beta-HSD3 with an IC(50) of 194.8+/-1.0 microM. The inhibitions of 3beta-HSD and 17beta-HSD3 by PFOA were competitive for the substrates. In conclusion, PFOA inhibits 3beta-HSD and 17beta-HSD3 in rat Leydig cells. Show less

Both glucocorticoid and insulin are known to have an anabolic effect on lipogenesis. Acetyl-CoA, an intermediate product of glycolysis, is supplied for fatty acid synthesis when carbohydrate intake is sufficient. Acetyl-CoA carboxylase (ACC), consisting of two isoenzymes ACC1 and ACC2, mediates the conversion from acetyl-CoA to malonyl-CoA, and thus plays a key role for the regulation of lipogenesis. In this study, we surveyed the effects of glucocorticoid and insulin on the transcriptional activity of the alternative promoters of ACCs (PI-PIII for ACC1, and PI and PII for ACC2) using the HepG2 human hepatocyte cell line in vitro. We also examined the roles of the insulin and/or glucose-regulated transcriptional factor(s) such as SREBP1c, LXRalpha/beta, and ChREBP on each promoter of the ACC genes. We found that both insulin and glucocorticoid had potent positive effects on all the promoters examined, and additive effects of both hormones were recognized in ACC1 PI and ACC2 PI. Furthermore, a representative insulin-responsive transcription factor SREBP1c showed significant stimulatory effects on all the promoters of ACC genes, among which those on ACC1 PIII and ACC2 PI were most prominent. On the other hand, the effect of LXRalpha was rather selective; it showed a marked stimulatory effect only on ACC1 PII. LXRbeta and ChREBP had minimal, if any, effects on some of the promoters. Altogether, our data suggest that insulin and glucocorticoid have positive effects on both ACC1 and ACC2 gene transcription. SREBP1c might be a master regulator of the expression of both genes regardless of the promoter utilized, whereas LXRalpha seems to play a promoter-specific role. Since ACC1 facilitates lipogenesis by stimulating fatty acid synthesis and ACC2 inhibits lipolysis, both insulin and glucocorticoid seem to play an important role in the pathogenesis of obesity and/or hepatic steatosis. Show less

To determine the effects and potential mechanisms of ibrolipim on ATP-binding membrane cassette transporter A-1 (ABCA1) and ATP-binding membrane cassette transporter G-1 (ABCG1) expression from human macrophage foam cells, which may play a critical role in atherogenesis. Human THP-1 cells pre-incubated with ox-LDL served as foam cell models. Specific mRNA was quantified using real-time RT-PCR and protein expression using Western blotting. Cellular cholesterol handling was studied using cholesterol efflux experiments and high performance liquid chromatography assays. Ibrolipim 5 and 50 μmol/L significantly increased cholesterol efflux from THP-1 macrophage-derived foam cells to apoA-I or HDL. Moreover, it upregulated the expression of ABCA1 and ABCG1. In addition, LXRα was also upregulated by the ibrolipim treatment. In addition, LXRα small interfering RNA completely abolished the promotion effect that was induced by ibrolipim. Ibrolipim increased ABCA1 and ABCG1 expression and promoted cholesterol efflux, which was mediated by the LXRα signaling pathway. Show less

The metabolic syndrome constitutes a group of metabolic conditions that increase the risk of developing diseases, including cardiovascular disease (CVD) and type 2 diabetes (T2D). LXRα/β are regulators of lipogenesis, cholesterol/glucose homoeostasis and inflammatory pathways, processes that are intertwined with development of the metabolic syndrome. The employment of LXRs as pharmaceutical targets for treatment of various aspects of the metabolic syndrome has been promptly investigated but serious side effects, like hepatic steatosis, have hampered this process. Novel treatment regimes now focus on development of isoform-specific or tissue-specific LXR agonist/antagonist compounds to circumvent effects on lipid biosynthesis. Other strategies to explore the beneficial aspects of LXR activation include targeting co-factors or pathways that are modifying LXR activity. Show less

Cholesterol 7alpha-hydroxylase (Cyp7a1) and the bile acid pool size are increased 2 to 3-fold in lactating postpartum rats. We investigated the interaction of nuclear receptors with the Cyp7a1 proximal promoter and the expression of regulatory signaling pathways in postpartum rats at day 10 (PPd10) versus female controls to identify the mechanisms of increased expression of Cyp7a1, which is maximal at 16 hours. Liver X receptor (LXRalpha) and RNA polymerase II (RNA Pol II) recruitment to Cyp7a1 chromatin were increased 1.5- and 2.5-fold, respectively, at 16 hours on PPd10. Expression of nuclear receptors farnesoid X receptor (FXR), LXRalpha, liver receptor homolog (LRH-1), hepatocyte nuclear factor 4alpha (HNF4alpha), and short heterodimer partner (SHP) messenger RNA (mRNA) and coactivator peroxisome proliferators-activated receptor gamma coactivator-1alpha (PGC-1alpha) mRNA was unchanged in PPd10 versus controls at 16 hours, whereas chicken ovalbumin upstream transcription factor II (COUP-TFII) was decreased 40% at 16 hours. Investigation of a repressive signaling pathway, the c-Jun-N-terminal kinase (JNK) signaling pathway in PPd10 versus controls, showed decreased mRNA expression of hepatocyte growth factor (HGF; decreased 60% at 16 hours) and tyrosine kinase receptor c-Met (decreased 44%-50% at 16 hours), but these were not accompanied by decreased expression of phosphorylated c-Jun. Importantly, expression of fibroblast growth factor 15 (FGF15) mRNA in the ileum was decreased 70% in PPd10 versus controls, whereas phosphorylated mitogen-activated protein kinase/extracellular signal-regulated kinase 1/2 (Erk1/2) protein expression in liver was decreased 88% at 16 hours. The increased recruitment of LXRalpha, a Cyp7a1 stimulatory pathway, and decreased expression of FGF15 and phosphorylated Erk1/2, a Cyp7a1 repressive pathway, combined to increase Cyp7a1 expression during lactation. Show less

The liver X receptors (LXRs) are nuclear receptors that are activated by endogenous oxysterols, oxidized derivatives of cholesterol. There are two isoforms of LXR, LXRalpha (NR1H3) and LXRbeta (NR1H2). Both LXRalpha and LXRbeta regulate gene expression by binding to DNA sequences associated with target genes as heterodimers with isoforms of the retinoid X receptor (RXR), RXRalpha (NR2B1), RXRbeta (NR2B2), and RXRgamma (NR2B3). LXRs act as cholesterol sensors: when cellular oxysterols accumulate as a result of increasing concentrations of cholesterol, LXR induces the transcription of genes that protect cells from cholesterol overload. In this review, we summarize the roles of LXRs in controlling cholesterol homeostasis, including their roles in bile acid synthesis and metabolism/excretion, reverse cholesterol transport, cholesterol biosynthesis and uptake, and cholesterol absorption/excretion in the intestine. The overlapping and distinct roles of the LXRalpha and LXRbeta isoforms, and the potential use of LXRs as attractive targets for treatment of cardiovascular disease are also discussed. Show less

To identify loci for age at menarche, we performed a meta-analysis of 32 genome-wide association studies in 87,802 women of European descent, with replication in up to 14,731 women. In addition to the known loci at LIN28B (P = 5.4 × 10⁻⁶⁰) and 9q31.2 (P = 2.2 × 10⁻³³), we identified 30 new menarche loci (all P < 5 × 10⁻⁸) and found suggestive evidence for a further 10 loci (P < 1.9 × 10⁻⁶). The new loci included four previously associated with body mass index (in or near FTO, SEC16B, TRA2B and TMEM18), three in or near other genes implicated in energy homeostasis (BSX, CRTC1 and MCHR2) and three in or near genes implicated in hormonal regulation (INHBA, PCSK2 and RXRG). Ingenuity and gene-set enrichment pathway analyses identified coenzyme A and fatty acid biosynthesis as biological processes related to menarche timing. Show less

Large-scale genome-wide association (GWA) studies have thus far identified 16 loci incontrovertibly associated with obesity-related traits in adults. We examined associations of variants in these loci with anthropometric traits in children and adolescents. Seventeen variants representing 16 obesity susceptibility loci were genotyped in 1,252 children (mean ± SD age 9.7 ± 0.4 years) and 790 adolescents (15.5 ± 0.5 years) from the European Youth Heart Study (EYHS). We tested for association of individual variants and a genetic predisposition score (GPS-17), calculated by summing the number of effect alleles, with anthropometric traits. For 13 variants, summary statistics for associations with BMI were meta-analyzed with previously reported data (N(total) = 13,071 children and adolescents). In EYHS, 15 variants showed associations or trends with anthropometric traits that were directionally consistent with earlier reports in adults. The meta-analysis showed directionally consistent associations with BMI for all 13 variants, of which 9 were significant (0.033-0.098 SD/allele; P < 0.05). The near-TMEM18 variant had the strongest effect (0.098 SD/allele P = 8.5 × 10(-11)). Effect sizes for BMI tended to be more pronounced in children and adolescents than reported earlier in adults for variants in or near SEC16B, TMEM18, and KCTD15, (0.028-0.035 SD/allele higher) and less pronounced for rs925946 in BDNF (0.028 SD/allele lower). Each additional effect allele in the GPS-17 was associated with an increase of 0.034 SD in BMI (P = 3.6 × 10(-5)), 0.039 SD, in sum of skinfolds (P = 1.7 × 10(-7)), and 0.022 SD in waist circumference (P = 1.7 × 10(-4)), which is comparable with reported results in adults (0.039 SD/allele for BMI and 0.033 SD/allele for waist circumference). Most obesity susceptibility loci identified by GWA studies in adults are already associated with anthropometric traits in children/adolescents. Whereas the association of some variants may differ with age, the cumulative effect size is similar. Show less

The cultivated peanut is a valuable source of dietary oil and ranks fifth among the world oil crops. Plant fatty acid biosynthesis is catalysed by type II fatty acid synthase (FAS) in plastids and mitochondria. By constructing a full-length cDNA library derived from immature peanut seeds and homology-based cloning, candidate genes of acyl carrier protein (ACP), malonyl-CoA:ACP transacylase, beta-ketoacyl-ACP synthase (I, II, III), beta-ketoacyl-ACP reductase, beta-hydroxyacyl-ACP dehydrase and enoyl-ACP reductase were isolated. Sequence alignments revealed that primary structures of type II FAS enzymes were highly conserved in higher plants and the catalytic residues were strictly conserved in Escherichia coli and higher plants. Homologue numbers of each type II FAS gene expressing in developing peanut seeds varied from 1 in KASII, KASIII and HD to 5 in ENR. The number of single-nucleotide polymorphisms (SNPs) was quite different in each gene. Peanut type II FAS genes were predicted to target plastids except ACP2 and ACP3. The results suggested that peanut may contain two type II FAS systems in plastids and mitochondria. The type II FAS enzymes in higher plants may have similar functions as those in E. coli. Show less

To seek the special plasma molecule in unstable angina (UA) patients of qi deficiency and blood stasis syndrome (QDBS) and method for explore the proteomic specificity of the disease. LC-MS(E) analysis was performed in UA patients of QDBS or non-QDBS and in healthy persons after the 6 proteins with optimal abundance in plasma being removed by polyclonal antibody affinity column (product of Agilent Co. USA). Actin were found only expressed, and FN, ApoH and ANXA6 were found highly expressed in plasma of patients with UA-QDBS, suggesting they might be the special molecules for the disease. Moreover, as compared with health persons, SAA, CP, MYH11 and C6 showed high expression, and the 6 proteins, e.g. A1BG, ApoA4, GSN, HBB, HBD and TF, showed low expression in the plasma of UA-QDBS patients. UA-QDBS might belong to a kind inflammatory reaction. There are simultaneous existence of myocardial injury, blood coagulation factor abnormality, lipid metabolic disorder and oxygen transport obstacle in patients of UA-QDBS, they influence and interact mutually. The newly discovered differential proteins might provide clues for studying or discovering new protein targets of angina relieving drugs. The new technique of label free quantitative proteomics is an efficient method for bio-marker research of diseases and syndromes. Show less

To explore the relationship between serum apolipoprotein A5 (ApoA5) and lipid profile or high sensitive C-reactive protein (hs-CRP) in patients with acute coronary syndrome (ACS). Serum apoA5 and hs-CRP levels were measured by ELISA and immunoturbidimetry in control subjects (n = 232), patients with stable angina (SA, n = 127), unstable angina (UA, n = 116) and acute myocardial infarction (AMI, n = 112). Triglyceride (TG), total cholesterol (TC), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were also measured. Compared with controls [(108.7 +/- 23.2) microg/L] and SA patients [(78.3 +/- 20.2) microg/L], serum ApoA5 level was significantly increased in UA [(340.6 +/- 63.5) microg/L] and AMI patients [(373.2 +/- 73.8) microg/L] (all P < 0.05). ApoA5 was positively correlated with TG (r = 0.63 and 0.67, respectively, all P < 0.05) and hs-CRP (r = 0.57 and 0.55, respectively, all P < 0.05) in UA and AMI patients but there were no significant correlations between ApoA5 and TC, HDL-C and LDL-C in ACS patients (all P > 0.05). Increased serum apoA5 level and the positive correlation between ApoA5 and serum TG and hs-CRP in ACS patients might reflect increased inflammation responses in ACS patients. Show less

Combining statin and fibrate in clinical practice provides a greater reduction of triglycerides than either drug given alone, but the mechanism for this effect is poorly understood. Apolipoprotein AV (apoAV) has been implicated in triglyceride metabolism. This study was designed to investigate the effect of the combination of statin and fibrate on apoAV and the underlying mechanism(s). Hypertriglyceridaemia was induced in rats by giving them 10% fructose in drinking water for 2 weeks. They were then treated with atorvastatin, fenofibrate or the two agents combined for 4 weeks, and plasma triglyceride and apoAV measured. We also tested the effects of these two agents on triglycerides and apoAV in HepG2 cells in culture. Western blot and reverse transcription polymerase chain reaction was used to measure apoAV and peroxisome proliferator-activated receptor-alpha (PPARalpha) expression. The combination of atorvastatin and fenofibrate resulted in a greater decrease in plasma triglycerides and a greater increase in plasma and hepatic apoAV than either agent given alone. Hepatic expression of the PPARalpha was also more extensively up-regulated in rats treated with the combination. A similar, greater increase in apoAV and a greater decrease in triglycerides were observed following treatment of HepG2 cells pre-exposed to fructose), with the combination. Adding an inhibitor of PPARalpha (MK886) abolished the effects of atorvastatin on HepG2 cells. A combination of atorvastatin and fenofibrate increased apoAV and decreased triglycerides through up-regulation of PPARalpha. Show less

Increased triglyceride (TG) occurs in patients with acute coronary syndrome (ACS), and apolipoprotein AV (apoAV) has been shown to lower TG levels. In the present study, we investigated plasma apoAV level and its relationship with TG and C-reactive protein (CRP) in ACS patients. A total of 459 subjects were recruited and categorized into control group (n = 116), stable angina (SA) group (n = 115), unstable angina group (n = 116) and acute myocardial infarction group (n = 112). Plasma apoAV level was measured by a sandwich ELISA assay. Compared with controls ((100.27 +/- 22.44) ng/ml), plasma apoAV was decreased in SA patients ((76.54 +/- 16.91) ng/ml) but increased in patients with unstable angina ((330.89 +/- 66.48) ng/ml, P < 0.05) or acute myocardial infarction ((368.66 +/- 60.53) ng/ml, P < 0.05). Inverse correlations between apoAV and TG were observed in the control or stable angina groups (r = -0.573 or -0.603, respectively, P < 0.001), whereas positive correlations were observed in the patients with unstable angina or acute myocardial infarction (r = 0.696 or 0.690, respectively, P < 0.001). Furthermore, a positive relationship between apoAV and CRP was observed in the ACS patients but not in the non-ACS subjects. The plasma apoAV concentration is increased and positively correlates with TG and CRP in ACS patients. Show less

Dyslipidemia is common in patients with acute coronary syndromes (ACS) but the mechanism remains unclear. Apolipoprotein AV (apoAV), a novel member of apolipoprotein family, is involved in lipid metabolism. This study was to investigate plasma apoAV level and its association with lipids and high-sensitivity C-reactive protein (hs-CRP) in ACS patients. ACS patients (n=228) and healthy volunteers (n=232) were included. Plasma apoAV levels were measured by an ELISA method. Compared with controls, ACS patients had higher plasma apoAV, hs-CRP, triglycerides, total cholesterol and LDL cholesterol, as well as lower HDL cholesterol. Interestingly, a positive correlation was observed between apoAV and triglycerides in ACS patients, as compared with a negative correlation in controls. Notably, logistic regression analysis showed that plasma apoAV level was an independent predictor of ACS (OR=0.82, 95% CI 0.70-0.95, p<0.05). Furthermore, both apoAV and triglycerides were positively associated with hs-CRP in ACS patients. However, no significant correlations between apoAV and cholesterol including total cholesterol, HDL cholesterol and LDL cholesterol were observed in ACS patients. Thus, apoAV is an independent predictor of ACS although increased plasma apoAV level is positively correlated with triglycerides in ACS patients. Moreover, plasma cholesterol levels are not influenced by apoAV in ACS patients. Show less

Hereditary multiple exostoses (HME) is an autosomal dominant disorder characterized by formation of benign cartilage-capped tumors (exostoses), typically located at the juxtaepiphyseal regions of long bones. It is genetically heterogeneous with at least three chromosomal loci: EXT1 on 8q24.1, EXT2 on 11p11, and EXT3 on 19p. EXT1 and EXT2 have been cloned and are responsible for over 80% of cases. A Chinese family with HME has been analyzed in the present study. Linkage analysis was firstly performed to determine which of the three EXT genes could be the candidate gene, then mutation screening by PCR and direct sequencing was carried out. A novel nonsense mutation (c.1006C>T) in exon 6 of EXT2, which converts the codon CAA (Gln) to the stop codon (TAA) (Gln336X), was identified. Next, prenatal diagnosis was performed and the pregnancy was determined to be normal. A new EXT2 nonsense mutation was found in a Chinese family with hereditary multipe exostoses. The information was used for a case of prenatal diagnosis. Show less