👤 Cen Xie

The aim is to investigate the association between coronary heart disease (CHD) and c.553G>T polymorphism of apolipoprotein A5 (ApoA5) gene and the influence of serum lipid level in the Han ethnic population of Xinjiang. The polymorphism of ApoA5 gene in 486 patients with CHD and 501 controls was analyzed by methods of polymerase chain reaction and restriction fragment length polymorphism analysis. Level of serum lipid in each patient was detected at the same time. There was significant difference in the distribution of genotypes between CHD group and controls group (χ(2)=8.757, P=0.013). Non-conditioned logistic regression analyses, after adjusted for age, gender, smoking, total serum cholesterol, presence of hypertension and diabetes, revealed that individuals who carried T allele (TT + GT genotype) had an increased risk of CHD, compared to GG genotype (OR=1.753, 95%CI: 1.030-2.983, P<0.05). There was also a remarkable difference noticed in the level of serum triglyceride by genotypes in CHD group and control group (t=-5.242, P<0.01; t=-3.499, P=0.001). Individuals in the two groups who carried T allele had higher level of serum triglyceride than those carried GG genotype. Individuals in CHD group who carried T allele had higher level of serum total cholesterol than those carried GG genotype (t=-2.465, P=0.014). It seemed that the c.553G>T polymorphism of ApoA5 gene had influenced on the level of serum triglyceride and the total cholesterol among Han population in Xinjiang. c.553G>T polymorphism was associated with the development of CHD, while T allele might be an influencing risk factor on CHD. Show less

To investigate the association of the -12238T/C polymorphism of apolipoprotein A5 (APOA5) gene with coronary heart disease (CHD) and the influence of serum lipid levels in Chinese Uygur population of Xinjiang. The -12238T/C polymorphism of APOA5 gene in 344 patients with CHD and 408 controls was analyzed by polymerase chain reaction-restriction fragment length polymorphism; the serum lipid levels were detected as well. The frequencies of CC, TC and TT genotype were 6.69%, 43.31% and 50.00% in the CHD group, while they were 14.95%, 45.10% and 39.95% in the control group. There was significant difference in the distribution of genotypes between the two groups (P < 0.01). Logistic regression analyses adjusted for age, gender, smoking, serum total cholesterol, presence of hypertension and diabetes revealed that individuals carrying CC genotype had an increased risk of CHD compared with TT genotype (OR = 0.328, 95%CI: 0.154-0.700). There was also significant difference in serum triglyceride level in genotypes between these two groups (P < 0.01). Patients in CHD group who carried CC and TC genotypes had lower serum triglyceride level than the TT genotype carriers. The -12238T/C polymorphism of APOA5 gene has influence on the serum triglyceride level in Uygur population of Xinjianxg. This polymorphism might be associated with development of CHD, and the CC genotype might be a protective factor in the development of CHD. Show less

Axin1 is a critical negative regulator of the canonical Wnt-signaling pathway. It is a concentration-limiting factor in the β-catenin degradation complex. Axin1 null mutant mouse embryos died at embryonic day 9.5, precluding direct genetic analysis of the roles of Axin1 in many developmental and physiological processes using these mutant mice. In this study, we have generated mice carrying two directly repeated loxP sites flanking the exon 2 region of the Axin1 gene. We show that floxed-allele-carrying mice (Axin1( fx/fx) ) mice appear normal and fertile. Upon crossing the Axin1( fx/fx) mice to the CMV-Cre transgenic mice, the loxP-flanked exon 2 region that encodes the N-terminus and the conserved regulation of G-protein signaling domain was efficiently deleted by Cre-mediated excision in vivo. Moreover, we show that mouse embryos homozygous for the Cre/loxP-mediated deletion of exon 2 of the Axin1 gene display embryonic lethality and developmental defects similar to those reported for Axin1(-/-) mice. Thus, this Axin1(fx/fx) mouse model will be valuable for systematic tissue-specific dissection of the roles of Axin1 in embryonic and postnatal development and diseases. Show less

To investigate the association between the polymorphisms of fatty acid desaturase 1 (FADS1), fatty acid desaturase 2 (FADS2) and elongation of very long chain fatty acids like 2 (ELOVL2) gene and coronary artery disease (CAD) in a Chinese Han population. Three single nucleotide polymorphisms (SNPs) from these genes were genotyped using PCR-based restriction fragment length polymorphism analysis in 199 CAD cases and 192 controls of Han Chinese origin. rs174556 in the FADS1 gene showed allelic (P=0.002) and genotypic (P=0.030) association with the disease, while there was no disease association for the other two SNPs. The frequency of rs174556 minor allele (T) was significantly higher in the case group than the control group. The trans phase gene-gene interaction analysis showed that the combined genotype of rs174556 (T/T) and rs3756963 (T/T) was weakly associated with the disease (P=0.043). rs174556 in the FADS1 gene is very likely to be associated with CAD in the Chinese Han population. Show less

To investigate an association between gene polymorphisms of FADS 1 (fatty acid desaturase 1) , FADS2 (fatty acid desaturase 2) and ELOVL2 (elongation of very long chain fatty acids (FEN1/ Elo2, SUR4/Elo3, yeast) -like 2) and paranoid schizophrenia of the Han ethnicity in Jilin province of China. We genotyped 3 single nucleotide polymorphisms from 3 candidate genes in 100 paranoid schizophrenia cases and 95 healthy controls using polymerase chain reaction-restriction fragment length polymorphism method. All samples are from Han ethnicity in Jilin province of China. The genotype distributions of rs174556 in FADS1 gene and rs174617 in FADS2 gene showed no significant difference between case and control groups (P > 0.05). The genotype distribution of rs3756963 in ELOVL2 gene showed significant difference between case group and control group (P < 0.05). The distribution proportion of allele T carriers in case group was higher than that in control group. Trans-phase gene interaction analysis showed that the distribution proportion of combined genotypes included rs3756963 (T/T) was higher in case group than that in control group (P < 0.05). rs174556 in FADS1 gene and rs174617 in FADS2 gene may not be associated with paranoid schizophrenia. rs3756963 in ELOVL2 gene may be associated with paranoid schizophrenia. Show less

Congenital heart disease (CHD) is the malformation of the heart during embryonic development, contributing to the inadequate function of the heart. A recently suggested gene hairy-related transcription factor 2 (HEY2), is an important determinant of mammalian heart development and functions thereby. We had preformed a direct sequencing within 768 Chinese CHD patients in the HEY2 gene. However, we did not reveal any diagnostic alterations in the coding regions by direct sequencing in HEY2, nevertheless this work expands our knowledge of the causes of CHD in the other way. Show less

The nuclear receptor liver X receptor (LXR) is a ligand-dependent transcription factor that plays an important role in the metabolism and homeostasis of cholesterol, lipids, bile acids, and steroid hormones. MicroRNAs (miRNAs) are recently recognized important negative regulators of gene expression. In this report, we showed that miRNA hsa-miR-613 played an important role in the autoregulation of the human LXRα gene. hsa-miR-613 targeted the endogenous LXRα through its specific miRNA response element (613MRE) within the LXRα 3'-untranslated region. Interestingly and paradoxically, the expression of hsa-miR-613 itself was induced upon the activation of LXR. However, hsa-miR-613 did not appear to be a direct LXR target gene. Instead, the positive regulation of hsa-miR-613 by LXR was mediated by the sterol regulatory element binding protein (SREBP)-1c, a known LXR target gene. Promoter analysis revealed an SREBP response element in the hsa-miR-613 gene promoter. Treatment with insulin also induced the expression of hsa-miR-613 in an SREBP-1c-dependent manner, further supporting the role of SREBP-1c in the positive regulation of this miRNA species. Finally, the autoinduction of LXRα by a LXR agonist was enhanced when hsa-miR-613 was inhibited or SREBP-1c was down-regulated. hsa-miR-613 appeared to specifically target the human LXRα. We propose that the negative regulation mediated by hsa-miR-613 and SREBP-1c and the previously reported positive regulation mediated by an LXR response element in the LXRα gene promoter constitute a ying-yang mechanism to ensure a tight regulation of this nuclear receptor of many metabolic functions. Show less

Proinsulin is a precursor of mature insulin and C-peptide. Higher circulating proinsulin levels are associated with impaired β-cell function, raised glucose levels, insulin resistance, and type 2 diabetes (T2D). Studies of the insulin processing pathway could provide new insights about T2D pathophysiology. We have conducted a meta-analysis of genome-wide association tests of ∼2.5 million genotyped or imputed single nucleotide polymorphisms (SNPs) and fasting proinsulin levels in 10,701 nondiabetic adults of European ancestry, with follow-up of 23 loci in up to 16,378 individuals, using additive genetic models adjusted for age, sex, fasting insulin, and study-specific covariates. Nine SNPs at eight loci were associated with proinsulin levels (P < 5 × 10(-8)). Two loci (LARP6 and SGSM2) have not been previously related to metabolic traits, one (MADD) has been associated with fasting glucose, one (PCSK1) has been implicated in obesity, and four (TCF7L2, SLC30A8, VPS13C/C2CD4A/B, and ARAP1, formerly CENTD2) increase T2D risk. The proinsulin-raising allele of ARAP1 was associated with a lower fasting glucose (P = 1.7 × 10(-4)), improved β-cell function (P = 1.1 × 10(-5)), and lower risk of T2D (odds ratio 0.88; P = 7.8 × 10(-6)). Notably, PCSK1 encodes the protein prohormone convertase 1/3, the first enzyme in the insulin processing pathway. A genotype score composed of the nine proinsulin-raising alleles was not associated with coronary disease in two large case-control datasets. We have identified nine genetic variants associated with fasting proinsulin. Our findings illuminate the biology underlying glucose homeostasis and T2D development in humans and argue against a direct role of proinsulin in coronary artery disease pathogenesis. Show less

MicroRNAs are small non-coding RNA molecules that play essential roles in biological processes ranging from cell cycle to cell migration and invasion. Accumulating evidence suggests that miR-34a, as a key mediator of p53 tumor suppression, is aberrantly expressed in human cancers. In the present study, we aimed to explore the precise biological role of miR-34a and the global protein changes in HCC cell line HepG2 cells transiently transfected with miR-34a. Transfection of miR-34a into HepG2 cells caused suppression of cell proliferation, inhibition of cell migration and invasion. It also induced an accumulation of HepG2 cells in G1 phase. Among 116 protein spots with differential expression separated by 2-DE method, 34 proteins were successfully identified by MALDI-TOF/TOF analysis. Of these, 15 downregulated proteins may be downstream targets of miR-34a. Bioinformatics analysis produced a protein-protein interaction network, which revealed that the p53 signaling pathway and cell cycle pathway were two major hubs containing most of the proteins regulated by miR-34a. Cytoskeletal proteins such as LMNA, GFAP, MACF1, ALDH2, and LOC100129335 are potential targets of miR-34a. In conclusion, abrogation of miR-34a function could cause downstream molecules to switch on or off, leading to HCC development. Show less

The liver X receptor (LXR) and constitutive androstane receptor (CAR) are two nuclear receptors postulated to have distinct functions. LXR is a sterol sensor that promotes lipogenesis, whereas CAR is a xenosensor that controls xenobiotic responses. Here, we show that LXRα and CAR are functionally related in vivo. Loss of CAR increased the expression of lipogenic LXR target genes, leading to increased hepatic triglyceride accumulation, whereas activation of CAR inhibited the expression of LXR target genes and LXR ligand-induced lipogenesis. On the other hand, a combined loss of LXR α and β increased the basal expression of xenobiotic CAR target genes, whereas activation of LXR inhibited the expression of CAR target genes and sensitized mice to xenobiotic toxicants. The mutual suppression between LXRα and CAR was also observed in cell culture and reporter gene assays. LXRα, like CAR, exhibited constitutive activity in the absence of an exogenously added ligand by recruiting nuclear receptor coactivators. Interestingly, although CAR competed with LXRα for coactivators, the constitutive activity and recruitment of coactivators was not required for CAR to suppress the activity of LXRα. In vivo chromatin immunoprecipitation assay showed that cotreatment of a CAR agonist compromised the LXR agonist responsive recruitment of LXRα to Srebp-1c, whereas an LXR agonist inhibited the CAR agonist-responsive recruitment of CAR to Cyp2b10. In conclusion, our results have revealed dual functions of LXRα and CAR in lipogenesis and xenobiotic responses, establishing a unique role of these two receptors in integrating xenobiotic and endobiotic homeostasis. Show less

The FADS1/FADS2 gene cluster encodes Delta-5 and Delta-6 desaturase, rate-limiting enzymes in metabolism of linoleic (LA) to arachidonic (ARA) and alpha-linolenic to eicosapentaenoic and docosahexaenoic acid (DHA). Single nucleotide polymorphisms (SNPs) in FADS1/FADS2 contribute to variability in blood lipid fatty acids. Altered n-6 and n-3 fatty acids have been related to perinatal depression (PPD). We genotyped rs174553, rs99780, rs174575, and rs174583 in FADS1/FADS2, analyzed blood lipid fatty acids and assessed PPD risk as an Edinburgh Postnatal Depression Scale (EPDS) score > or =10 for 69 pregnant women. 21, 12 and 15% women had an EPDS score > or =10 at 36 weeks' gestation, 2 and 6 months postpartum, respectively. Quantitative trait analysis showed an association between rs174575 and PPD risk at 36 weeks' gestation and 6 months postpartum. With haplotype ACCC (major alleles) for rs174553, rs99780, rs174575, rs174583, respectively, as reference, GTCT was positively associated with PPD risk at 36 weeks' gestation, p = 0.028, and higher LA and lower ARA in plasma (p = 0.0001, p < 0.0001) and RBC ethanolamine phospholipids (p = 0.007, p = 0.005). We show that SNPs in FADS1/FADS2 are associated with higher blood lipid LA and lower ARA and PPD risk. Show less

To screen the MYBPC3 gene mutations in Han Chinese patients with hypertrophic cardiomyopathy (HCM). Sixty-six patients with HCM were enrolled for the study. The exons in the functional regions of MYBPC3 were amplified with PCR and the products were sequenced. Four novel mutations and four common polymorphisms were identified in this patient cohort. A Lys301fs mutation in exon10 was evidenced in a H30, and when he was 47 years old, he had the chest tightness, shortness of breath with septal hypertrophy of 18.7mm; a Asp463stop mutation in exon17 was detected in a H48, he was 24 years old 24-year-old when a medical examination showed ventricular septal hypertrophy of 15.4 mm; both Gly523Arg mutation in exon18 and Tyr847His mutation in exon26 were found in a H53 with onset age 36 years old, feeling chest tightness after excise and his ventricular septal hypertrophy was 27 mm that time. MYBPC3 mutations occurred in 4.5% patients in this cohort. These mutations were not found in 100 non-HCM control patients. MYBPC3 mutation is presented in a small portion of Han Chinese patients with HCM. Show less

The liver X receptors (LXRs) have been known as sterol sensors that impact cholesterol and lipid homeostasis, as well as inflammation. Although the hepatic functions of LXRs are well documented, whether and how LXRs play a pathophysiological role in the lung remain largely unknown. Here we show that LXRalpha and LXRbeta are expressed in both type I and type II mouse lung epithelial cells, as well as in human lung cancer cells. To study the role of LXRalpha in vivo including the pulmonary function of this LXR isoform, we created LXRalpha knock-in (LXR-KI) mice in which a constitutively activated LXRalpha (VP-LXRalpha) was inserted into the mouse LXRalpha locus. We show that activation of LXR in LXR-KI mice or LXR agonist-treated wild type mice induced pulmonary expression of genes encoding multiple antioxidant enzymes. Consistent with the induction of antioxidant enzymes, LXR-KI mice and LXR ligand-treated wild type mice showed a substantial resistance to lipopolysaccharide-induced lung injury and decreased production of reactive oxygen species. In summary, we have uncovered a novel role of LXR in regulating antioxidant enzymes in the lung and the implication of this regulation in pulmonary tissue protection. Show less

GIP is an important hormonal link between nutrition and bone formation. We show for the first time that BMSCs express functional GIP receptors, that expression decreases with aging, and that elevations in GIP can prevent age-associated bone loss. We previously showed that C57BL/6 mice lose bone mass as they age, particularly between 18 and 24 mo of age. The mechanisms involved in this age-dependent induced bone loss are probably multifactorial, but adequate nutrition and nutritional signals seem to be important. Glucose-dependent insulinotropic peptide (GIP) is an enteric hormone whose receptors are present in osteoblasts, and GIP is known to stimulate osteoblastic activity in vitro. In vivo, GIP-overexpressing C57BL/6 transgenic (GIP Tg(+)) mice have increased bone mass compared with controls. Bone histomorphometric data suggest that GIP increases osteoblast number, possibly by preventing osteoblastic apoptosis. However, potential GIP effects on osteoblastic precursors, bone marrow stromal cells (BMSCs), had not previously been examined. In addition, effects of GIP on age-induced bone loss were not known. Changes in BMD, biomechanics, biomarkers of bone turnover, and bone histology were assessed in C57BL/6 GIP Tg(+) versus Tg(-) (littermate) mice between the ages of 1 and 24 mo of age. In addition, age-related changes in GIP receptor (GIPR) expression and GIP effects on differentiation of BMSCs were also assessed as potential causal factors in aging-induced bone loss. We report that bone mass and bone strength in GIP Tg(+) mice did not drop in a similar age-dependent fashion as in controls. In addition, biomarker measurements showed that GIP Tg(+) mice had increased osteoblastic activity compared with wildtype control mice. Finally, we report for the first time that BMSCs express GIPR, that the expression decreases in an age-dependent manner, and that stimulation of BMSCs with GIP led to increased osteoblastic differentiation. Our data show that elevated GIP levels prevent age-related loss of bone mass and bone strength and suggest that age-related decreases in GIP receptor expression in BMSCs may play a pathophysiological role in this bone loss. We conclude that elevations in GIP may be an effective countermeasure to age-induced bone loss. Show less

The enzymes encoded by fatty acid desaturase (FADS) 1 and FADS2 are rate-limiting enzymes in the desaturation of linoleic acid [LA; 18:2(n-6)] to arachidonic acid [ARA; 20:4(n-6)], and alpha-linolenic acid [ALA; 18:3(n-3)] to eicosapentaenoic acid [EPA; 20:5(n-3)] and docosahexaenoic acid [DHA; 22:6(n-3)]. ARA, EPA, and DHA play central roles in infant growth, neural development, and immune function. The maternal ARA, EPA, and DHA status in gestation influences maternal-to-infant transfer and breast milk provides fatty acids for infants after birth. We determined if single nucleotide polymorphisms in FADS1 and FADS2 influence plasma phospholipid and erythrocyte ethanolamine phosphoglyceride (EPG) (n-6) and (n-3) fatty acids of women in pregnancy or their breast milk during lactation. We genotyped rs174553, rs99780, rs174575, and rs174583 in the FADS1 FADS2 gene cluster and analyzed plasma and erythrocyte fatty acids and dietary intake for 69 pregnant women and breast milk for a subset of 54 women exclusively breast-feeding at 1 mo postpartum. Minor allele homozygotes of rs174553(GG), rs99780(TT), and rs174583(TT) had lower ARA but higher LA in plasma phospholipids and erythrocyte EPG and decreased (n-6) and (n-3) fatty acid product:precursor ratios at 16 and 36 wk of gestation. Breast milk fatty acids were influenced by genotype, with significantly lower 14:0, ARA, and EPA but higher 20:2(n-6) in the minor allele homozygotes of rs174553(GG), rs99780(TT), and rs174583(TT) and lower ARA, EPA, 22:5(n-3), and DHA in the minor allele homozygotes G/G of rs174575. We showed that genetic variants of FADS1 and FADS2 influence blood lipid and breast milk essential fatty acids in pregnancy and lactation. Show less

To investigate the effects of Ginkgo biloba extract (EGB) on the testosterone synthesis in the Leydig cells of type 2 diabetic rats. Thirty male SD rats were equally randomised into a normal control, a type 2 diabetic and an EGB group. Morphological changes of Leydig cells were observed by light microscopy (LM) and transmission electron microscopy (TEM), concentrations of serum luteinizing hormone (LH) and testosterone (T) were determined by enzyme linked immunosorbent assay (ELISA), and the mRNA levels in the steroidogenic acute regulatory protein (StAR), cytochrome P450 side chain cleavage (P450scc), cytochrome P450 17a-hydroxylase (P450c17), 17beta-hydroxysteroid dehydrogenase 3 (17beta-HSD3) and 3beta-hydroxysteroid dehydrogenase (3beta-HSD1) from the Leydig cells were examined by RT-PCR. Compared with the normal control, there was a significant decrease in the number and volume of Leydig cells, the levels of serum LH and T and the expression of mRNA in StAR, P450scc, 17beta-HSD3 and 3beta-HSD1 in the type 2 diabetes group. And the expression of the P450c17 gene showed a tendency of descending, but with no significance. Compared with the type 2 diabetes group, 12 weeks of EGB treatment caused very slight pathological changes in the Leydig cells, significantly increased the concentrations of blood LH and T, markedly elevated the levels of mRNA in StAR and P450scc and induced an ascending tendency of the expressions of P450c17, 17beta-HSD3 and 3beta-HSD1. EGB enhances testosterone synthesis and secretion of Leydig cells by reducing the impairment of the testis in type 2 diabetic rats. Show less

Liver X receptor (LXR) is known to promote hepatic lipogenesis by activating the lipogenic transcriptional factor sterol regulatory element-binding protein (Srebp). Pregnane X receptor (PXR), a previously known "xenobiotic receptor," could mediate a Srebp-independent lipogenic pathway by activating the free fatty acid uptake transporter Cd36. The goal of this study is to investigate further the role of Cd36 in hepatic steatosis. Wild-type, LXR transgenic, PXR transgenic, and Cd36 null mice were used to study the regulation of Cd36 and other hepatic lipogenic genes and the implication of this regulation in hepatic steatosis. Promoter sequences of Cd36 and peroxisome proliferator-activated receptor (PPAR) gamma were cloned, and their respective regulation by LXR and PXR was investigated by combinations of receptor-DNA binding and reporter gene assays. We showed that genetic (transgene) or pharmacologic (ligands) activation of LXR induced Cd36. Promoter analysis established Cd36 as a novel transcription target of LXRalpha. Moreover, the hepatic steatosis induced by LXR agonists was largely abolished in Cd36 null mice. We also showed that PPARgamma, a positive regulator of Cd36, is a transcriptional target of PXR, suggesting that PXR can regulate Cd36 directly or through its activation of PPARgamma. Interestingly, both LXR-mediated Cd36 regulation and PXR-mediated PPARgamma regulation are liver specific. We conclude that Cd36 is a shared target of LXR, PXR, and PPARgamma. The network of CD36 regulation by LXR, PXR, and PPARgamma establishes this free fatty acid transporter as a common target of orphan nuclear receptors in their mediation of lipid homeostasis. Show less

PXR was isolated as a "xenobiotic receptor" that regulates drug-metabolizing enzymes and transporters, whereas LXR is known to promote hepatic lipogenesis by activating the lipogenic transcriptional factor sterol regulatory element-binding protein (SREBP). We have recently shown that PXR can mediate a SREBP-independent lipogenic pathway by activating the free fatty acid (FFA) uptake transporter CD36, PPARgamma, and several accessory lipogenic enzymes, such as stearoyl CoA desaturase-1 (SCD-1) and long-chain free fatty acid elongase (FAE). More recently, we found activation of LXR also induced the expression of CD36. Promoter analysis established CD36 as a novel transcriptional target of LXRalpha. Moreover, the steatotic effect of LXR agonists was largely abolished in CD36 null mice, suggesting an essential role for CD36 and FFA uptake in LXR-mediated steatosis. We also showed that PPARgamma, a positive regulator of CD36, is also a transcriptional target of PXR. Thus, PXR can regulate CD36 directly or through its activation of PPARgamma. Interestingly, PXR- and LXR-mediated CD36 activation and PXR-mediated PPARgamma activation are all liver-specific. We conclude that CD36 is a shared target of LXR, PXR, and PPARgamma. The network of CD36 regulation controlled by LXR, PXR, and PPARgamma establishes this FFA transporter as a common target of orphan nuclear receptors in their mediation of hepatic steatosis. It is hoped that the nuclear receptor-mediated CD36 regulation may offer novel targets for the therapeutic management of alcoholic and nonalcoholic steatosis. Show less

The retinoid-related orphan receptors (RORs) and liver X receptors (LXRs) were postulated to have distinct functions. RORs play a role in tissue development and circadian rhythm, whereas LXRs are sterol sensors that affect lipid homeostasis. In this study, we revealed a novel function of RORalpha (NR1F1) in regulating the oxysterol 7alpha-hydroxylase (Cyp7b1), an enzyme critical for the homeostasis of cholesterol, bile acids, and oxysterols. The expression of Cyp7b1 gene was suppressed in the RORalpha null (RORalpha(sg/sg)) mice, suggesting RORalpha as a positive regulator of Cyp7b1. Promoter analysis established Cyp7b1 as a transcriptional target of RORalpha, and transfection of RORalpha induced the expression of endogenous Cyp7b1 in the liver. Interestingly, Cyp7b1 regulation seemed to be RORalpha-specific, because RORgamma had little effect. Reporter gene analysis showed that the activation of Cyp7b1 gene promoter by RORalpha was suppressed by LXRalpha (NR1H3), whereas RORalpha inhibited both the constitutive and ligand-dependent activities of LXRalpha. The mutual suppression between RORalpha and LXR was supported by the in vivo observation that loss of RORalpha increased the expression of selected LXR target genes, leading to hepatic triglyceride accumulation. Likewise, mice deficient of LXR alpha and beta isoforms showed activation of selected RORalpha target genes. Our results have revealed a novel role for RORalpha and a functional interplay between RORalpha and LXR in regulating endo- and xenobiotic genes, which may have broad implications in metabolic homeostasis. Show less

To explore the disease associated gene mutation of multiple exostoses by family analysis. Polymerase chain reaction and DNA sequencing were used to detect the mutation hot spot regions of EXT1 and EXT2 gene, while restriction fragment length polymorphism was performed to screen the mutation. We found a novel heterozygous mutation c.811T ->C in EXT1 gene of patients, which resulted in the substitution of histidine for tyrosine at codon 271 in this hereditary multiple exostoses family. The mutation was not found in the unaffected family members, nor in the 100 unrelated normal individual, which was unreported before. The novel mutation Y271H is the disease-causing mutation in the hereditary multiple exostoses family. Show less

To study the gene mutation in a patient with multiple exostoses, identify the disease-causing gene mutation. Polymerase chain reaction and DNA sequencing were used to screen the EXT1 or EXT2 gene mutation, while mismatch primer amplification and restriction endonuclease digestion were performed to confirm the mutation. By DNA sequencing, a mutation in the seventh intron was detected and located at 26 bp of 3' splice site upstream in EXT1 gene, which was unreported before. Mismatch primer amplification and restriction fragment length polymorphism analysis suggested that this mutation was not detected in the normal control. The mutation 1633-26(C-->A) may be the disease-causing mutation in this patient with multiple exostoses. Show less

Human protein kinases make up a large superfamily of homologous proteins, which are related by virtue of their kinase domains (also known as catalytic domains). Here we report the cloning and characterization of a novel human MAST4 (microtubule associated serine/threonine kinase family member 4) gene, which locates on human chromosome 5q13. The MAST4 cDNA is 7587 base pairs in length and encodes a putative protein of 2435 amino acids which contains a serine/threonine kinase domain and a PDZ domain. MAST4 protein has 64%, 63%, 59% and 39% identical aminoacid residues with MAST1, MAST2, MAST3 and MASTL respectively. RT-PCR analysis revealed relatively high expression level of MAST4 in most normal human tissues, with an exception of in testis, small intestine, colon and peripheral blood leukocyte. Show less

To compare the gene mutation between Chinese patients with familial and sporadic hypertrophic cardiomyopathy (HCM). Peripheral blood samples were collected from 36 patients with familial HCM (FHCM) and 50 patients with sporadic HCM (SHCM), all un-related and from different provinces of China. PCR was used to amplify the 26 protein-coding axons of beta-myosin heavy chain (MYH7), 16 exons for cardiac troponin T (TNNT2), and 38 exons for cardiac myosin-binding protein C (MYBPC3). The amplified products were sequenced and compared with the standard sequence in the genBank so as to determine the potential mutation sites. (1) 13 of the 36 FHCM patients (36.1%) harbored 3 different mutations in MYH7 gene: Arg663His in exon18, Glu924Lys in exon 23, and Ile736Thr in exon 20. Of the 50 SHCM patients, only 1 (2%) harbored MYH7 gene missence mutation: Ile736Thr located in exon 20. (2) TNNT2 was not identified in all SHCM patients and FHCM patients. (3) MYBPC3 was not identified in all SHCM patients. Four FHCM patients harbored 2 different mutations: Arg502Trp in exon 18 and Arg346fs in exon 13 respectively. MYH7 and MYBPC3 may be the dominant disease-causing genes in Chinese familial HCM patients; however the mutation rate of MYH7 and MYBPC3 genes is significantly lower in the SHCM patients compared with the FHCM patients. TNNT2 seems not the predominant disease-causing gene in all Chinese patients with HCM. Show less

The aim of this study was to screen the disease-causing gene mutations and investigate the genotype-phenotype correlation in 10 Chinese pedigrees with familial hypertrophic cardiomyopathy (HCM). There are 91 family members from these 10 pedigrees and 5 members were normal mutated carriers, 23 members were HCM patients (14 male) aged from 1.5 to 73 years old. The functional regions of myosin heavy chain gene (MYH7), cardiac myosin-binding protein C (MYBPC3) and cardiac troponin T gene (TNNT2) were screened with PCR and direct sequencing technique. Clinical information from all patients was also evaluated in regard to the genotype. Mutations were found in 5 out of 10 pedigrees. Mutations in MYH7 (Arg663His, Glu924Lys and Ile736Thr) were found in 3 pedigrees and 3 patients from these pedigrees suffered sudden death at age 20-48 years old during sport. Mutations in MYBPC3 were found in 2 pedigrees, 1 with complex mutation (Arg502Trp and splicing mutation IVS27 + 12C > T) and 1 with novel frame shift mutation (Gly347fs) and the latter pedigree has sudden death history. No mutation was identified in TNNT2. Although the Han Chinese is a relatively homogeneous ethnic group, different HCM gene mutations were responsible for familiar HCM suggesting the heterogeneity nature of the disease-causing genes and HCM MYH7 mutations are associated with a higher risk of sudden death in this cohort. Furthermore, identical mutation might result in different phenotypes suggesting that multiple factors might be involved in the pathogenesis of familiar HCM. Show less

Glucose-dependent insulinotropic polypeptide (GIP) is an incretin hormone, which is secreted from endocrine cells in the small intestine after meal ingestion. GIP has been shown to affect osteoblastic function in vitro; however, the in vivo effects of GIP on bone remodeling remain unclear. In the present study, we investigated the role of GIP in modulating bone turnover, by evaluating serum markers of bone turnover, bone density, bone morphology, and changes in biomechanical bone strength over time (one to five months) in GIP receptor knockout mice (GIPR-/- mice). The GIPR-/- mice showed a decreased bone size, lower bone mass, altered bone microarchitecture and biomechanical properties, and altered parameters for bone turnover, especially in bone formation. Moreover, the effects of GIP on bone mass were site-specific and compensatory mechanism developed over time and ameliorated the impact of the loss of GIP signaling on bone mass. Further, GIPR-/- mice had earlier age-related changes than wild-type mice in body composition, including bone mass, lean body mass, and fat percentage. In summary, our results indicate that GIP has an anabolic effect on bone mass and bone quality and suggests that GIP may be a hormonal link between nutrient ingestion and utilization. Show less

To explore the disease-causing gene mutation in Chinese with hypertrophic cardiomyopathy (HCM). The peripheral venous blood samples were collected from 5 HCM families without consanguinity, including 5 probands, 2 males and 3 females, 28 sporadic HCM patients, 18 males and 10 females, and 80 healthy controls. The exons in the functional regions of cardiac myosin-binding protein C (MYBPC3) were amplified with PCR and the amplified products were sequenced. A frame shift mutation-Arg346fs mutation in exon 13, the first mutation identified in Chinese-was discovered in one family with HCM. However, the members of the same HCM family with the Arg346fs mutation showed differences in phenotype and prognosis. Cardiac myosin-binding protein C (MYBPC3) may be one of the main disease-causing genes. The heterogeneity of phenotype suggests that multiple factors may be involved in the pathogenesis. Show less

Bardet-Biedl syndrome (BBS) is a heterogeneous multisystemic disorder characterized primarily by five cardinal features of retinal degeneration, obesity, polydactyly, hypogenitalism and mental retardation. To date, six distinct BBS loci that have been identified on different chromosomes. BBS4 gene is mapped to 15q22.2-23, which when mutated can cause BBS4. Its protein shows strong homology to O-linked N-acetylglucosamine (O-GlcNAc) transferase. Here we report a splice variant of BBS4, which is 2556 bp in length and has an open reading frame coding a predicted 527 amino-acids protein. RT-PCR shows that the cDNA is widely expressed while it has higher expression levels in pancreas, liver and prostate. Show less

Mammalian enterocytes express apolipoprotein (apo)B-48, which is produced after posttranscriptional RNA editing of the nuclear apoB-100 transcript by the catalytic deaminase apobec-1. Earlier studies in apobec-1-/- mice revealed an apoB-100-only lipoprotein profile but no gross defects in triglyceride absorption. However, subtle defects may have been obscured by the mixed genetic background. In addition, the intrinsic susceptibility to proteolytic degradation of intestinal apoB-100 and apoB-48 has been questioned. Accordingly, we examined triglyceride absorption, intestinal apoB expression, and lipoprotein secretion in apobec-1-/- mice backcrossed into a C57BL/6 background. Inbred apobec-1-/- mice absorb triglyceride normally, yet secrete triglyceride-rich lipoproteins more slowly than wild-type congenic controls. There was comparable induction of apoB synthesis in response to fat feeding in both genotypes, but apoB-100 was preferentially retained and more extensively degraded than apoB-48. By contrast, synthesis, secretion, and content of apo A-IV were indistinguishable in apobec-1-/- and wild-type mice with 100% recovery, suggesting no degradation of this apoprotein in either genotype. Newly secreted lipoproteins from isolated enterocytes of wild-type mice revealed apoB-48 in both high-density lipoproteins and very low-density lipoproteins. By contrast, apobec-1-/- mice secreted apoB-100-containing particles that were almost exclusively in the low and very low-density lipoproteins range with no apoB-100-containing high-density lipoproteins. These studies establish the existence of preferential degradation of intestinal apoB-100 and subtle defects in triglyceride secretion in apobec-1-/- mice, coupled with a shift to the production of larger particles, findings that suggest an important divergence in intestinal lipoprotein assembly pathways with the different isoforms of apoB. Show less