RESUMO
BACKGROUND: Hyperlipidaemia is a major risk factor for cardiovascular disease, and atherosclerosis is the underlying cause of both myocardial infarction and stroke. We have previously shown that the Pro251 variant of perilipin-2 reduces plasma triglycerides and may therefore be beneficial to reduce atherosclerosis development. OBJECTIVE: We sought to delineate putative beneficial effects of the Pro251 variant of perlipin-2 on subclinical atherosclerosis and the mechanism by which it acts. METHODS: A pan-European cohort of high-risk individuals where carotid intima-media thickness has been assessed was adopted. Human primary monocyte-derived macrophages were prepared from whole blood from individuals recruited by perilipin-2 genotype or from buffy coats from the Karolinska University hospital blood central. RESULTS: The Pro251 variant of perilipin-2 is associated with decreased intima-media thickness at baseline and over 30 months of follow-up. Using human primary monocyte-derived macrophages from carriers of the beneficial Pro251 variant, we show that this variant increases autophagy activity, cholesterol efflux and a controlled inflammatory response. Through extensive mechanistic studies, we demonstrate that increase in autophagy activity is accompanied with an increase in liver-X-receptor (LXR) activity and that LXR and autophagy reciprocally activate each other in a feed-forward loop, regulated by CYP27A1 and 27OH-cholesterol. CONCLUSIONS: For the first time, we show that perilipin-2 affects susceptibility to human atherosclerosis through activation of autophagy and stimulation of cholesterol efflux. We demonstrate that perilipin-2 modulates levels of the LXR ligand 27OH-cholesterol and initiates a feed-forward loop where LXR and autophagy reciprocally activate each other; the mechanism by which perilipin-2 exerts its beneficial effects on subclinical atherosclerosis.
Assuntos
Aterosclerose/metabolismo , Autofagia , Espessura Intima-Media Carotídea , Receptores X do Fígado/metabolismo , Macrófagos/metabolismo , Perilipina-2/metabolismo , Idoso , Progressão da Doença , Europa (Continente) , Feminino , Células Espumosas/metabolismo , Humanos , Lipoproteínas/metabolismo , Estudos Longitudinais , Masculino , Pessoa de Meia-IdadeRESUMO
OBJECTIVES: Deficiency in the catabolism of triglyceride-rich lipoproteins is the main cause of childhood-onset chylomicronaemia syndrome. Missense mutations in lipoprotein lipase (LPL) or in proteins influencing LPL activity or stability have been shown to be critical determinants of chylomicronaemia syndrome. The main objective of this study was to assess the primary deficiency in five cases of childhood-onset chylomicronaemia syndrome. SETTING: Lipid clinic at a university hospital, SUBJECTS: Subjects presenting with severe hypertriglyceridaemia and chylomicronaemia syndrome in which reduced LPL activity and mass were observed. INTERVENTIONS: Analysis of LPL and GPIHBP1 genes. RESULTS: Amongst the five patients, one novel homozygous missense mutation (p.C68Y) in exon 3 of GPIHBP1 was identified. The other four patients were homozygous for the common LPL mutation p.G188E. CONCLUSION: These findings provide further evidence that GPIHBP1 is involved in the catabolism of triglyceride-rich lipoproteins and plays a role in childhood-onset chylomicronaemia.
Assuntos
Proteínas de Transporte/genética , Quilomícrons/sangue , Hipertrigliceridemia/sangue , Lipase Lipoproteica/sangue , Mutação de Sentido Incorreto , Idade de Início , Criança , Quilomícrons/genética , Éxons , Feminino , Homozigoto , Humanos , Lipase Lipoproteica/genética , Lipase Lipoproteica/metabolismo , Masculino , Receptores de Lipoproteínas , SíndromeRESUMO
AIMS/HYPOTHESIS: It has recently been suggested that the rs738409 G allele in PNPLA3, which encodes adiponutrin, is strongly associated with increased liver fat content in three different ethnic groups. The aims of the present study were as follows: (1) to try to replicate these findings in European individuals with quantitative measures of hepatic fat content; (2) to study whether the polymorphism influences hepatic and adipose tissue insulin sensitivity; and (3) to investigate whether PNPLA3 expression is altered in the human fatty liver. METHODS: We genotyped 291 Finnish individuals in whom liver fat had been measured using proton magnetic resonance spectroscopy. Hepatic PNPLA3 expression was measured in 32 participants. Hepatic and adipose tissue insulin sensitivities were measured using a euglycaemic-hyperinsulinaemic (insulin infusion 0.3 mU kg(-1) min(-1)) clamp technique combined with infusion of [3-(3)H]glucose in 109 participants. RESULTS: The rs738409 G allele in PNPLA3 was associated with increased quantitative measures of liver fat content (p = 0.011) and serum aspartate aminotransferase concentrations (p = 0.002) independently of age, sex and BMI. Fasting serum insulin and hepatic and adipose tissue insulin sensitivity were related to liver fat content independently of genotype status. PNPLA3 mRNA expression in the liver was positively related to obesity (r = 0.62, p < 0.0001) and to liver fat content (r = 0.58, p = 0.025) in participants who were not morbidly obese (BMI < 40 kg/m(2)). CONCLUSIONS/INTERPRETATION: A common variant in PNPLA3 increases the risk of hepatic steatosis in humans.
Assuntos
Fígado Gorduroso/genética , Lipase/genética , Proteínas de Membrana/genética , Adulto , Idoso , Índice de Massa Corporal , Fígado Gorduroso/sangue , Fígado Gorduroso/metabolismo , Feminino , Predisposição Genética para Doença , Genótipo , Técnica Clamp de Glucose , Humanos , Espectroscopia de Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Obesidade/genética , Reação em Cadeia da PolimeraseRESUMO
Gene therapy to deliver and express a corrective lipoprotein lipase (LPL) gene may improve the lipid profile and reduce the morbidity and potential atherogenic risk from hypertriglyceridemia and dyslipoproteinemia in patients with complete or partial LPL deficiency. We have used an E1-/E3- adenoviral vector, with an RSV-driven human LPL cDNA expression cassette (Ad-RSV-LPL), to achieve high ectopic LPL gene expression in the human hepatoma cell line HepG2, an accepted hepatocellular model of lipoprotein metabolism. Ad-RSV-LPL transduction of HepG2 cells with a multiplicity of infection (moi) between 12.5 and 100 yielded dose-dependent increments in LPL mass and activity. Peak levels of LPL protein of 2,032.1 +/- 274.5 ng/10(5) cells per ml (mol 100) correlated with increased activity of 92.7 +/- 22.6 mU/10(5) cells per ml relative to negligible LPL levels in Ad-RSV-LacZ (beta-galactosidase) controls. Exogenous LPL expression over a 5-day period peaked at day 3. Susceptibility to inhibition by 1 M NaCl and an anti-LPL monoclonal antibody confirmed that lipase activity was indeed derived from human LPL. Hydrolysis, by LPL-overexpressing HepG2 cells, of TG carried in very-low-density lipoprotein (VLDL) showed that greater than 50% of the triglycerides (TG) disappeared after 4 hr of incubation. These results were compatible with FPLC evidence of a marked reduction in VLDL-TG. These results provide strong in vitro evidence that adenoviral-mediated ectopic expression of the human LPL gene could render hepatic cells capable of VLDL catabolism and thus support the possibility for in vivo adenoviral vector-mediated liver-targeted LPL gene therapy.
Assuntos
Adenoviridae/genética , Carcinoma Hepatocelular/metabolismo , Vetores Genéticos/genética , Lipase Lipoproteica/genética , Lipase Lipoproteica/metabolismo , Proteínas E1 de Adenovirus/genética , Proteínas E3 de Adenovirus/genética , Vírus do Sarcoma Aviário/genética , Carcinoma Hepatocelular/genética , Carcinoma Hepatocelular/patologia , DNA Complementar/genética , Regulação Neoplásica da Expressão Gênica , Regulação Viral da Expressão Gênica , Técnicas de Transferência de Genes , Humanos , Hidrólise , Lipoproteínas VLDL/química , Lipoproteínas VLDL/metabolismo , Processamento de Proteína Pós-Traducional , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Triglicerídeos/química , Triglicerídeos/metabolismo , Células Tumorais CultivadasRESUMO
Previous work has shown that neuroblastoma cells secrete IGFBP-2, -4 and -6 and that expression of these proteins is regulated by retinoic acid (at-RA) which promotes differentiation in these cells. Other agents also induce differentiation of neuroblastoma cells: these include the 9- cis and 13- cis isomers of at-RA, 1,25 dihydroxy- vitamin D3 (VD3), triidothyronine (T3) and 12-O-tetradecanoyl phorbol 13-acetate (TPA). Nine- cis and 13- cis isomers of at-RA increased IGFBP-6 expression, but decreased IGFBP-2 and IGFBP-4. VD3 stimulated IGFBP-6 and IGFBP-2 expression, whereas T3 inhibited IGFBP-6 expression without affecting IGFBP-2. TPA markedly enhanced expression of all three IGFBPs produced by SK-N-SH cells. Since IGFBP-6 secretion is associated with the arrest of proliferation in neuroblastoma cells and is regulated by the combined actions of differentiation factors, we subcloned the proximal promoter of human IGFBP-6 (nt -766/+1) into a pCAT expression vector so as to examine modulation of its transcriptional activity. VD3 and TPA were capable of stimulating promoter activity, T3 depressed it and at-RA and its 9- cis and 13- cis isomers had no effect. These results confirm the high sensitivity of IGFBP-6 expression to these differentiation agents, essentially at transcriptional level.
Assuntos
Proteína 6 de Ligação a Fator de Crescimento Semelhante à Insulina/biossíntese , Neuroblastoma/metabolismo , Antineoplásicos/farmacologia , Sequência de Bases , Northern Blotting , Western Blotting , Carcinógenos , Divisão Celular , Cloranfenicol O-Acetiltransferase/metabolismo , Colecalciferol/farmacologia , Clonagem Molecular , Regulação para Baixo , Humanos , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina/biossíntese , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina/biossíntese , Proteína 6 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Isomerismo , Luciferases/metabolismo , Modelos Genéticos , Dados de Sequência Molecular , Plasmídeos/metabolismo , Regiões Promotoras Genéticas , RNA/metabolismo , Análise de Sequência de DNA , Acetato de Tetradecanoilforbol , Transcrição Gênica/efeitos dos fármacos , Tretinoína/farmacologia , Tri-Iodotironina/farmacologia , Células Tumorais Cultivadas , Regulação para CimaRESUMO
Peroxisome proliferator activated receptors (PPARs) are nuclear receptors regulating the expression of genes involved in lipid and glucose metabolism. Three different PPARs; alpha (PPARA), gamma (PPARG) and delta (PPARD) have been characterized and they are distinguished from each other by tissue distribution and cell activation. In this study, the structure and detailed chromosomal localization of the human PPARD gene was determined. Three genomic clones containing the PPARD gene was isolated from a human P1 library. The gene spans approximately 85 kb of DNA and consists of 9 exons and 8 introns with exons ranging in size from 84 bp to 2.3 kb and introns ranging from 180 bp to 50 kb. All splice acceptor and donor sites conform to the consensus sequences including the AG-GT motif. Although PPARD lacks a TATA box, the gene is transcribed from a unique start site located 380 bp upstream of the ATG initiation codon. The 5' and 3' ends were mapped by rapid amplification of cDNA ends and the mRNA size of PPARD based upon the structure of the gene is 3803 bp. In addition, the chromosomal sublocalization of PPARD was determined by radiation hybrid mapping. The PPARD gene is located at 14 cR from the colipase gene and 15 cR from the serine kinase gene at chromosomal region 6p21.2.
Assuntos
Receptores Citoplasmáticos e Nucleares/genética , Fatores de Transcrição/genética , Adulto , Autorradiografia , Sequência de Bases , Northern Blotting , Cromossomos Humanos Par 6 , Éxons , Humanos , Íntrons , Dados de Sequência Molecular , Especificidade de Órgãos , Mapeamento Físico do Cromossomo , Reação em Cadeia da Polimerase , Regiões Promotoras Genéticas , RNA Mensageiro/análise , Receptores Citoplasmáticos e Nucleares/metabolismo , Análise de Sequência de DNA , Fatores de Transcrição/metabolismoAssuntos
Neoplasias Encefálicas/metabolismo , Proteínas de Transporte/biossíntese , Glioblastoma/metabolismo , Fator de Crescimento Insulin-Like II/biossíntese , Fator de Crescimento Insulin-Like I/biossíntese , Neuroblastoma/metabolismo , Proteínas de Transporte/isolamento & purificação , Linhagem Celular , Expressão Gênica , Humanos , Proteína 1 de Ligação a Fator de Crescimento Semelhante à Insulina , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina , Proteína 4 de Ligação a Fator de Crescimento Semelhante à Insulina , Proteína 5 de Ligação a Fator de Crescimento Semelhante à Insulina , Proteína 6 de Ligação a Fator de Crescimento Semelhante à Insulina , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina , Peso Molecular , Proteínas de Neoplasias/biossíntese , Células Tumorais CultivadasRESUMO
The microsomal triglyceride transfer protein (MTTP) is essential for the assembly of VLDLs. We recently observed that a polymorphism in the MTTP promoter (-493G>T), which is in allelic association with an isoleucine-to-theronine substitution at position 128 (Ile128Thr) in the expressed protein, confers an increased risk of coronary heart disease. Two variant proteins comprising amino acids 16-297 of intact MTTP, MTTP(N)-Ile128 and MTTP(N)-Thr128, had similar native secondary structure content, as judged by circular dichroism. However, the thermal stability of MTTP(N)-Thr128 was greatly reduced, and this protein was also more extensively cleaved in limited proteolysis experiments compared with MTTP(N)-Ile128; both of these findings support a less compact fold. On adding LDL, which includes natively folded apolipoprotein B (apoB), decreased stability of the MTTP(N)-Thr128-LDL complex was observed compared with that of the MTTP(N)-Ile128-LDL complex. In a refined model of the N-terminal domain of MTTP, residue 128 is located in a surface-exposed position, in the same region as an identified MTTP binding site in the homologous apoB protein. Thus, the Ile128Thr polymorphism confers reduced structural stability, leading to decreased binding of MTTP to LDL particles. Because the major MTTP binding target on LDL is apoB, the Ile128Thr polymorphism could target the MTTP-apoB interaction.
Assuntos
Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Sequência de Aminoácidos , Substituição de Aminoácidos , Apolipoproteínas B/metabolismo , Sequência de Bases , Proteínas de Transporte/química , Quimotripsina , Dicroísmo Circular , Clonagem Molecular , DNA Complementar/genética , Estabilidade de Medicamentos , Humanos , Técnicas In Vitro , Cinética , Ligantes , Lipoproteínas LDL/metabolismo , Microssomos/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Polimorfismo Genético , Dobramento de Proteína , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homologia de Sequência de AminoácidosRESUMO
In extracellular fluids the insulin-like growth factors (IGFs) are bound to specific binding proteins (IGBPs). The genes for two members of this protein family have been mapped, the IGBP1 gene to human chromosomal region 7p14-p12 and the IGBP2 gene to region 2q33-q34. In this study, somatic cell hybrid analysis indicated that IGBP3 is also located on chromosome 7. Pulsed-field gel electrophoresis was used to demonstrate the close physical linkage between IGBP1 and IGBP3. Overlapping cosmid clones encompassing these genes were isolated, and restriction endonuclease mapping showed that the genes are arranged in a tail-to-tail fashion separated by 20 kb of DNA. Further characterization of the IGBP1 DNA sequence disclosed a duplication of the intron 3-exon 4 junction within the third intron. In addition, we report RFLPs for ApaLI and TaqI in the IGBP1 locus.
Assuntos
Proteínas de Transporte/genética , Cromossomos Humanos Par 7 , Sequência de Aminoácidos , Sequência de Bases , Southern Blotting , Linhagem Celular , Mapeamento Cromossômico , Clonagem Molecular , Cosmídeos , Sondas de DNA , Éxons , Ligação Genética , Humanos , Células Híbridas/fisiologia , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina , Íntrons , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos , Polimorfismo de Fragmento de Restrição , Mapeamento por Restrição , Somatomedinas/metabolismoRESUMO
OBJECTIVES: Peroxisome proliferator activated receptor delta (PPARD) is a transcription factor implicated in the regulation of genes involved in cholesterol metabolism. We recently discovered a common polymorphism in the 5'-untranslated region (5'-UTR) of the human PPARD, +294T/C, that is associated with an increased plasma low-density lipoprotein cholesterol (LDL-C) concentration in healthy subjects. Whether the +294C allele is associated with LDL-C elevation independently of the background lipoprotein phenotype and whether it confers increased risk of coronary heart disease (CHD) is unknown. Against this background, we investigated the relationships between the PPARD polymorphism and plasma lipoprotein concentrations and the risk for contracting CHD in the West of Scotland Coronary Prevention Study (WOSCOPS). DESIGN: A nested case-control study of participants in a randomized double-blind placebo-controlled trial of pravastatin in mildly-to-moderately hypercholesterolaemic men. SUBJECTS: A total of 580 cases of incident CHD and 1160 individuals who remained free of CHD (controls). MAIN OUTCOME MEASURES: Plasma lipoprotein concentrations and risk of CHD according to PPARD genotype. RESULTS: Individuals carrying the rare PPARD +294C allele had a significantly lower high-density lipoprotein cholesterol (HDL-C) concentration than subjects homozygous for the common T-allele. Homozygous carriers of the C-allele also showed a tendency towards higher risk of CHD compared with homozygous carriers of the T-allele. In addition, a gene-gene interaction involving the PPARD polymorphism and the PPAR alpha L162V polymorphism may influence the plasma LDL-C concentration. CONCLUSIONS: PPARD plays a role in cholesterol metabolism in man.
Assuntos
Doença das Coronárias/genética , Predisposição Genética para Doença , Hipercolesterolemia/genética , Receptores Citoplasmáticos e Nucleares/genética , Fatores de Transcrição/genética , Antropometria , Estudos de Casos e Controles , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Doença das Coronárias/sangue , Doença das Coronárias/etiologia , Genótipo , Humanos , Hipercolesterolemia/sangue , Hipercolesterolemia/complicações , Masculino , Pessoa de Meia-Idade , Polimorfismo Genético , Fatores de RiscoRESUMO
Insulin-like growth factors (IGF) I and II are bound to high-affinity binding proteins in the blood circulation and other body fluids. These IGF-binding proteins are expressed at different concentrations in different tissues and are thought to regulate the activity of IGF I and II. Cloned cDNA for IGF-binding protein-1 (IGFBP1) has been used to verify the location of its gene to human chromosome 7 by Southern blotting to DNA from a human-mouse hybrid cell line. Further, by in situ hybridization the gene was regionally localized to 7p14-p12, and a Mendelian-inherited two-allele BglII restriction enzyme length polymorphism was identified, with the most frequent allele occurring in 53% of the chromosomes.
Assuntos
Proteínas de Transporte/genética , Cromossomos Humanos Par 7 , Mapeamento Cromossômico , Cromossomos Humanos Par 7/ultraestrutura , DNA/genética , Genes , Humanos , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina , Hibridização de Ácido Nucleico , Polimorfismo de Fragmento de RestriçãoRESUMO
Insulin-like growth-factor-binding proteins (IGFBPs) constitute a family of structurally related proteins that specifically bind insulin-like growth factors and modulate their functions. In this study, the chromosomal localization was determined for the gene encoding IGFBP4, i.e. inhibitory-IGFBP. A polymerase chain reaction (PCR) fragment corresponding to the previously published cDNA sequence was used to isolate overlapping cosmid clones. By fluorescent in situ hybridization to metaphase chromosomes, the IGFBP4 gene was then localized to chromosomal region 17q21-21.1. This result was in agreement with PCR analysis of a panel of somatic cell hybrids.
Assuntos
Proteínas de Transporte/genética , Cromossomos Humanos Par 17 , Somatomedinas/genética , Sequência de Bases , Clonagem Molecular , Cosmídeos/genética , Fluorescência , Humanos , Células Híbridas , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Reação em Cadeia da PolimeraseRESUMO
Microsomal triglyceride transfer protein (MTP) is required for the assembly and cellular secretion of apolipoprotein B (apoB) -containing lipoproteins from the liver and intestine. The secretion pattern of apoB-containing lipoproteins is likely to influence the VLDL and LDL levels in plasma. By initial opportunistic screening for polymorphic sites in the regulatory region of the MTP gene by gene sequencing in 20 healthy male subjects, a common functional G/T polymorphism was detected 493 bp upstream from the transcriptional start point. There was differential binding of unique nuclear proteins at this site, as shown by electrophoretic mobility shift assay. The G variant seemed to bind two or three nuclear proteins that do not bind to the T variant. Expression studies with minimal promoter constructs linked to the chloramphenicol acetyltransferase reporter and transfected into HepG2 cells revealed marked enhancement of transcriptional activity with the T variant. The prevalence of the MTP promoter genotypes was investigated in a group of 184 healthy, middle-aged white men; the frequency of homozygosity for the MTP -493 T variant was .06 and the allele frequency of MTP -493T was .25 in the population. These homozygous subjects had a 22% lower LDL cholesterol concentration than did heterozygotes or subjects homozygous for the MTP -493 G variant (2.9+/-0.6 versus 3.7+/-0.8 mmol/L, P<.05). Analysis of apoB and triglyceride contents in VLDL subfractions revealed a markedly changed balance within the VLDL population. Subjects homozygous for the MTP -493 T variant had fewer but more lipid-rich VLDL particles, thereby arguing for an effect of MTP expression on the hepatic secretion of triglyceride-rich, apoB-containing lipoproteins. This common genetic variation of the MTP promoter is likely to have important implications for cardiovascular disease.
Assuntos
Proteínas de Transporte/genética , Lipoproteínas LDL/sangue , Microssomos Hepáticos , Polimorfismo Genético , Regiões Promotoras Genéticas , Adulto , Testes Genéticos , Humanos , Masculino , Pessoa de Meia-Idade , Células Tumorais CultivadasRESUMO
The insulin-like growth factor binding proteins (IGFBPs) have conserved characteristics of their genomic organization, including similar locations of exon borders relative to nucleotides encoding conserved cysteine residues. Furthermore, the human IGFBP genes, as well as the human homeobox (HOX) genes, are localized to chromosomes 2, 7, 12, and 17. Although little is known about the evolution of the IGFBP genes, the association of human IGFBP and homeobox (HOX) genes at four chromosomal loci may indicate that their ancestral genes were linked prior to the first duplication of chromosomal DNA containing the ancestral HOX cluster. The hypothesis that IGFBPs are ancient proteins is supported by the reported detection of IGFBP activity in serum from the Agnathan species, Geotria australis, a primitive vertebrate. Further studies of IGFBPs in different species are needed to understand the evolution of this protein/gene family. Chicken provides a good intermediate model, since birds diverged from mammals approximately 300 million years ago. A complementary DNA (cDNA) clone encoding chicken insulin-like growth factor binding protein-5 (cIGFBP-5) was isolated. The deduced amino acid sequence is 83% identical to human IGFBP-5 and encodes a mature polypeptide of 251 amino acids. The conservation of IGFBP-5 primary structure across vertebrate species suggests maintenance of important functions during evolution.
Assuntos
Evolução Molecular , Proteína 5 de Ligação a Fator de Crescimento Semelhante à Insulina/química , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/química , Sequência de Aminoácidos , Animais , Galinhas , Mapeamento Cromossômico , Sequência Conservada , Genes Homeobox , Humanos , Proteína 5 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Proteínas de Ligação a Fator de Crescimento Semelhante a Insulina/genética , Camundongos , Dados de Sequência Molecular , Fases de Leitura Aberta , Ratos , Somatomedinas/química , Somatomedinas/genética , XenopusRESUMO
OBJECTIVES: To investigate whether a substitution of glutamine by glutamic acid at amino acid position 27 (Q/E27) and an arginine to glycine transition at amino acid 16 (R/G16) in the beta2-adrenoceptor gene are associated with lipid and lipoprotein disturbances and/or increased body weight in men. DESIGN: Population-based study. SETTING: Department of medicine at a university hospital. SUBJECTS: A total of 180 healthy men, aged 30-45 years, were recruited at random from a register containing all permanent residents in Stockholm County (response rate of 70%). MAIN OUTCOME MEASURES: Frequency of beta2-adrenoceptor genotypes and alleles in relation to plasma lipid and lipoprotein levels and body mass index. RESULTS: Individuals carrying the E27 allele and/or the G16 allele had significantly higher body mass index (BMI). Furthermore, carriers of the E27 allele had significantly higher plasma concentrations of cholesterol, triglycerides, VLDL cholesterol and VLDL triglycerides than did subjects homozygous for the Q allele. CONCLUSION: The E27 allele of the beta2-adrenoceptor gene is associated with slightly to moderately elevated BMI and dyslipoproteinaemia involving triglyceride-rich lipoproteins in healthy younger and middle-aged men.
Assuntos
Peso Corporal , Colesterol/sangue , Hiperlipoproteinemias/genética , Mutação , Polimorfismo Genético , Receptores Adrenérgicos beta 2/genética , Triglicerídeos/sangue , Adulto , Alelos , Arginina/genética , VLDL-Colesterol/sangue , Genótipo , Ácido Glutâmico/genética , Glutamina/genética , Glicina/genética , Humanos , Hiperlipoproteinemias/sangue , Masculino , Pessoa de Meia-Idade , SuéciaRESUMO
Recent studies have provided evidence for associations between common polymorphic markers in the coagulation factor VII (FVII) gene and plasma FVII levels. Here we describe two common, nonrelated, functional polymorphisms in the promoter region of the FVII gene, a G to T substitution at position -401 and a novel G to A substitution at position -402. Both polymorphisms strongly influence the binding properties of nuclear protein(s). The rare -401T allele is associated with a reduced basal rate of transcription of the FVII gene in human hepatoblastoma cells and with reduced plasma concentrations of total FVII (VIIag) and fully activated FVII molecules (VIIa). In contrast, the rare -402A allele confers increased transcriptional activity and is associated with increased plasma FVII levels. Together, the two polymorphisms explained 18% and 28% of the variation in VIIag and VIIa, respectively, in a group of 183 healthy, middle-aged men. It is concluded that these polymorphisms are important for the regulation of the plasma levels of FVII and that they are likely to be useful genetic markers to resolve the issue of whether a causal relationship exists between FVII levels and risk of coronary heart disease.
Assuntos
Fator VII/genética , Fator VII/metabolismo , Polimorfismo Genético , Regiões Promotoras Genéticas , Adulto , Sequência de Bases , Sítios de Ligação , Carcinoma Hepatocelular , Primers do DNA , Fator VIIa/metabolismo , Regulação da Expressão Gênica , Genótipo , Humanos , Neoplasias Hepáticas , Masculino , Pessoa de Meia-Idade , Proteínas Nucleares/metabolismo , Mutação Puntual , Reação em Cadeia da Polimerase , Valores de Referência , Transcrição Gênica , Transfecção , Células Tumorais CultivadasRESUMO
Insulin-like growth factor binding proteins (IGFBPs) are extracellular proteins that specifically bind IGF and modulate their effects. The human IGFBP2 gene was studied and shown to be localized to chromosome 2 region q33-q34, by somatic cell hybrid analysis and in situ hybridization. Structural characterization of the gene showed that it consists of four exons with three introns of lengths 27.0, 1.0, and 1.9 kilobase-pairs. Comparison of the encoded protein sequence of each exon in IGFBP1, 2, and 3 reveals the highest amino acid identity, 28%, in exon 1, while the lowest was found in exon 2. However, pairwise sequence comparisons demonstrate 50% identity between the protein sequences encoded by exon 4 in IGFBP1 and 2, while their respective identities with IGFBP3 are only 25 and 30%.
Assuntos
Proteínas de Transporte/genética , Cromossomos Humanos Par 2 , Genes , Sequência de Aminoácidos , Animais , Sequência de Bases , Proteínas de Transporte/metabolismo , Linhagem Celular , Clonagem Molecular , Cosmídeos , Cricetinae , DNA/genética , DNA/isolamento & purificação , Éxons , Feminino , Biblioteca Genômica , Humanos , Células Híbridas/fisiologia , Proteína 2 de Ligação a Fator de Crescimento Semelhante à Insulina , Dados de Sequência Molecular , Sondas de Oligonucleotídeos , Placenta/metabolismo , Reação em Cadeia da Polimerase/métodos , Gravidez , Mapeamento por Restrição , Homologia de Sequência do Ácido NucleicoRESUMO
Insulin-like growth factor-binding protein 6 (IGFBP6), an extracellular protein with preferential affinity for insulin-like growth factor (IGF) II, belongs to a family of binding proteins with at least six members. We have characterized the genomic structure and the chromosomal location of the human IGFBP6, which is present in the human genome as a single-copy gene spanning 4.7 kb. It consists of four exons, encoding the translated regions, with sizes of 334, 146, 120, and 123 bp, while the intervening introns are 2661, 182, and 844 bp. Three mRNA cap sites were localized 101, 100, and 96 bp upstream of the ATG translation start codon as determined by S1 nuclease analysis. The proximal 5'-flanking region does not have any TATA or CAAT consensus sequences. The IGFBP6 was localized to Chr 12 by analysis of somatic cell hybrids and regionalized to 12q13 by fluorescence DNA in situ hybridization.
Assuntos
Cromossomos Humanos Par 12 , Genoma Humano , Proteína 6 de Ligação a Fator de Crescimento Semelhante à Insulina/genética , Sequência de Aminoácidos , Mapeamento Cromossômico , Éxons/genética , Humanos , Hibridização In Situ , Dados de Sequência Molecular , RNA Mensageiro/genética , Análise de SequênciaRESUMO
Lipoprotein lipase (LPL) is the rate-limiting enzyme for the hydrolysis of triglyceride-rich lipoproteins. Numerous LPL gene mutations have been described as a cause of familial chylomicronemia in various populations. In general, allelic heterogeneity is observed in LPL deficiency in different populations. However, a founder effect has been reported in certain populations, such as French Canadians. Although familial chylomicronemia is observed in Morocco, the molecular basis for the disease remains unknown. Here, we report two unrelated Moroccan families of Berber ancestry, ascertained independently in Holland and France. In both probands, familial chylomicronemia manifested in infancy and was complicated with acute pancreatitis at age 2 years. Both probands were homozygous for a Ser259Arg mutation, which results in the absence of LPL catalytic activity both in vivo and in vitro. In heterozygous relatives, a partial decrease in plasma LPL activity was observed, sometimes associated with combined hyperlipidemia. This mutation previously unreported in other populations segregated on an identical haplotype, rarely observed in Caucasians, in both families. Therefore, LPL deficiency is a cause of familial chylomicronemia in Morocco and may result from a founder effect in patients of Berber ancestry.