apoA-I Gene Research Articles

A novel compound 4010B-30 upregulates apolipoprotein A-I gene expression through activation of PPARγ in HepG2 cells

ObjectiveApolipoprotein (Apo) A-I is the major lipoprotein content of HDL and upregulating endogenous ApoA-I expression has been proposed as a desirable approach to raise the functional HDL. In this study we investigated the effect of a novel small molecule 4010B-30 on transcriptional regulation of ApoA-I gene in HepG2 cells, and the influence on the level of ApoA-I expression and function. Then the mechanisms by which 4010B-30 regulated ApoA-I expression was further explored. Methods and resultsIn human hepatic HepG2 cells, 4010B-30 increased the mRNA level and the protein production of ApoA-I both in cell lysates and media. The 4010B-30-induced ApoA-I containing particles increased cholesterol efflux from RAW264.7 macrophages. 4010B-30 also upregulated ABCA1 expression confirmed by transcriptional activity assay and Western blot analysis in both HepG2 and RAW264.7 cells. Promoter luciferase assay was used to identify the 4010B-30-responsive region which is mapped to the proximal −277bp region of the ApoA-I promoter. Further study indicated that the regulation of 4010B-30 on ApoA-I transcription or protein expression in HepG2 cells was abrogated with the suppression of PPARγ by its small interfering RNA or a specific inhibitor, GW9662. ConclusionsThese findings suggest that the novel small molecular upregulator 4010B-30 increases ApoA-I gene expression, thereby enhances its function of promoting cholesterol efflux, as well as ABCA1 expression in vitro, and activation of PPARγ is required for 4010B-30 to induce hepatic ApoA-I production.

Zebrafish as a model for apolipoprotein biology: comprehensive expression analysis and a role for ApoA-IV in regulating food intake.

Improved understanding of lipoproteins, particles that transport lipids throughout the circulation, is vital to developing new treatments for the dyslipidemias associated with metabolic syndrome. Apolipoproteins are a key component of lipoproteins. Apolipoproteins are proteins that structure lipoproteins and regulate lipid metabolism through control of cellular lipid exchange. Constraints of cell culture and mouse models mean that there is a need for a complementary model that can replicate the complex in vivo milieu that regulates apolipoprotein and lipoprotein biology. Here, we further establish the utility of the genetically tractable and optically clear larval zebrafish as a model of apolipoprotein biology. Gene ancestry analyses were implemented to determine the closest human orthologs of the zebrafish apolipoprotein A-I (apoA-I), apoB, apoE and apoA-IV genes and therefore ensure that they have been correctly named. Their expression patterns throughout development were also analyzed, by whole-mount mRNA in situ hybridization (ISH). The ISH results emphasized the importance of apolipoproteins in transporting yolk and dietary lipids: mRNA expression of all apolipoproteins was observed in the yolk syncytial layer, and intestinal and liver expression was observed from 4–6 days post-fertilization (dpf). Furthermore, real-time PCR confirmed that transcription of three of the four zebrafish apoA-IV genes was increased 4 hours after the onset of a 1-hour high-fat feed. Therefore, we tested the hypothesis that zebrafish ApoA-IV performs a conserved role to that in rat in the regulation of food intake by transiently overexpressing ApoA-IVb.1 in transgenic larvae and quantifying ingestion of co-fed fluorescently labeled fatty acid during a high-fat meal as an indicator of food intake. Indeed, ApoA-IVb.1 overexpression decreased food intake by approximately one-third. This study comprehensively describes the expression and function of eleven zebrafish apolipoproteins and serves as a springboard for future investigations to elucidate their roles in development and disease in the larval zebrafish model.

Relationship between the Apolipoprotein AI, B gene polymorphism and the risk of non-traumatic osteonecrosis.

BackgroundPrevious studies suggested that Apolipoprotein AI (ApoAI) and apolipoprotein B (ApoB) gene polymorphisms may result in lipid metabolism disorders. Genetic polymorphisms in these genes may be associated with the occurrence of osteonecrosis.MethodsWe designed a case-control study including 429 patients of osteonecrosis and 368 age- and sex-matched control subjects. Polymerase chain reaction was used to amplify the DNA fragments in promoter -75 G > A of ApoAI gene and EcoR I, Xba I and 3′-VNTR of ApoB gene in osteonecrosis patients and healthy controls. We utilized polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to genotype these four single nucleotide polymorphisms (SNPs).ResultsFor -75 G > A polymorphism of ApoAI, AA genotype frequency (0.501) was significantly higher in patients with osteonecrosis than that in control (0.462) subjects (P <0.001), GA genotype frequency (0.170) was significantly lower than that in the control (0.310) group (P <0.0001). In osteonecrosis patients, the odds ratio (OR) of A allele was 3.932 (95% CI: 3.0847 ~ 5.0123), which suggested that subjects carrying A allele of promoter region -75 G > A of ApoAI gene had higher susceptibility to osteonecrosis than G allele carriers. The genotype and allele frequency distributions showed no significant difference in EcoR I, Xba Iand 3′-VNTR loci of ApoB gene between the osteonecrosis group and control group.ConclusionOur study suggested that ApoAI gene -75G > A polymorphism may be associated with susceptibility to osteonecrosis in Chinese population. However, our results need further investigation with large sample size and various populations.

Evaluating the association of APOA2 polymorphism with insulin resistance in adolescents

Background265T>C SNP in the APOA-II gene promoter may be associated with obesity risk and insulin resistance (IR). This study aims to analyze the association between the APOA2 −265T>C SNP and risk for obesity and IR in adolescents. Material and methodsThe study was conducted on 500 adolescents. They were 240 obese and 260 non-obese individuals, aged 16–21years old. Their mean age was 18.25±2.54years. Variables examined body weight, height, waist circumference (WC), systolic and diastolic blood pressure (BP), body fat percentage (BF%), and abdominal visceral fat layer. Homeostasis Model Assessment of Insulin Resistance (HOMA-IR) was used as a biomarker for IR. BF% was assessed by body composition analyzer and abdominal visceral fat thickness was determined by ultrasonography. The APOA2 −265T>C polymorphism genotype was analyzed by PCR amplification of a 273-bp fragment. ResultsGenotype frequencies were in Hardy–Weinberg equilibrium. The frequency of the mutant C allele was significantly higher in obese cases than non-obese cases. After multivariate adjustment, waist, BF%, visceral adipose layer and HOMA-IR were significantly higher in homozygous allele CC carriers than TT+TC carriers. Homozygous individuals for the CC allele had statistically higher values of energy intake, total fat (g/day) and saturated fat (SATFAT) than carriers of the T allele. ConclusionsHomozygous individuals for the C allele had higher obesity risk than carriers of the T allele and had elevated levels of visceral adipose tissue. Moreover, the present study shows that the CC polymorphism is associated with the development of IR [OR 1.89 (1.35–2.91), P=.012] and remains significant after adjusting for gender, age and body mass index.

Haplotype analysis of ApoAI gene and sepsis-associated acute lung injury.

BackgroundApolipoprotein A1 (ApoA1) is the major apoprotein constituent of high density lipoprotein (HDL) which exerts innate protective effects in systemic inflammation. However, its role in the acute lung injury (ALI) has not been well studied. In the present study we investigated the association between polymorphisms of ApoA1 gene and ALI in a Chinese population.MethodsThree polymorphisms of the ApoA1 gene (rs11216153, rs2070665, and rs632153) were genotyped by TaqMan method in 290 patients with sepsis-associated ALI, 285 patients sepsis alone and 330 age- and sex-matched healthy controls.ResultsWe found rs11216153 polymorphism of ApoA1 was associated with ALI, the GG genotype and G allele was common in the ALI patients (76.9%, 88.1%, respectively) than both in the control subjects (55.8%, 75.8%, respectively) and in the sepsis alone patients (58.2%, 78.4%, respectively). Haplotype consisting of these three SNPs strengthened the association with ALI susceptibility. The frequency of haplotype GTG in the ALI samples was significantly higher than that in the healthy control group (OR = 2.261, 95% CI: 1.735 ~ 2.946, P <0.001) and the sepsis alone group (OR = 1.789, 95% CI: 1.373 ~ 2.331.P < 0.001). Carriers of the haplotype TTG had a lower risk for ALI compared with healthy control group (OR = 0.422, 95% CI: 0.310 ~ 0.574, P < 0.001) and sepsis alone group (OR = 0.491, 95% CI: 0.356 ~ 0.676, P <0.001).ConclusionsThese results indicated that genetic variants in the ApoA1 gene might be associated with susceptibility to sepsis-associated ALI in Han Chinese population.

Cloning and expression analysis of apolipoprotein A-I (ApoA-I) in the Hong Kong grouper (Epinephelus akaara)

Abstract Apolipoprotein A-I (ApoA-I) is the principal protein component of plasma high-density lipoprotein (HDL). It plays an important role in lipid transport and uptake and has been demonstrated to defend against bacteria in vertebrates. In this report, we identified a cDNA sequence from E. akaara ApoA-I with an ORF of 792 bp encoding a putative polypeptide of 263 amino acid residues that shares some common features with known vertebrate ApoA-I sequences. Tissue distribution analysis indicated that ApoA-I mRNA is broadly expressed in all tissues tested, including the fat metabolic organs (liver and intestine). We successfully expressed the ApoA-I gene using a pET28a(+) vector and acquired a highly purified protein that showed potent antimicrobial activity against the Gram-positive bacterium S. aureus as well as the Gram-negative bacteria E. coli, P. damselae and V. harveyi, indicating that ApoA-I may have a broad-spectrum antibacterial property to fish innate immunity. To determine the ApoA-I response to lipid metabolism, we analyzed the ApoA-I mRNA levels in the liver and intestine after feeding. The results indicate that intestinal ApoA-I becomes involved in fat metabolism approximately one hour (h) after feeding, followed by hepatic ApoA-I approximately 4 to 6 h post-feeding. Diversified types and proportions of dietary fatty acids did not affect the short-term levels of ApoA-I mRNA or plasma HDL-cholesterol in E. akaara. A chronic high-fat diet did not impact hepatic ApoA-I mRNA, although it decreased both intestinal ApoA-I mRNA and the plasma HDL-cholesterol levels. In addition, chronic high-fat diets caused fat deposition in hepatic tissues, which is most likely harmful to fish health. This work provides a unique basis for substantial future work and will be helpful to develop a successful diet for fish culture.

Apolipoproteins AI/B/E gene polymorphism and their plasma levels in patients with coronary artery disease in a tertiary care-center of Eastern India

The present study was designed to investigate whether the three-apolipoprotein (AI, B, E) gene polymorphisms were related to alter their plasma protein levels and hence associated to coronary artery disease (CAD). We determined distribution of MspI apo AI, EcoRI apo B, HhaI apo E gene polymorphisms, plasma apolipoproteins and lipids levels among 150 patients having CAD admitted to the Department of Cardiology, N.R.S. Medical College & Hospital, Kolkata, India during June 2010-June 2012 and 150 age sex matched healthy controls. We found that ApoAI concentration of studied population was significantly different in each genotypes of -75 G/A apo AI (p<0.0001) gene polymorphism. A significant association was found in multivariate analysis for the genotypes with apo E4 allele [odds ratio (OR): 3.639; 95% confidence interval (CI): 1.019-12.995, p=0.040] with four conventional risk factors (i.e. smoking, low-density lipoprotein, ApoAI and ApoB) with CAD. In contrast E2 allele has reverse effect, but the genotypes with apo E2 allele was no longer significant in the multivariate model (OR: 1.788; 95% CI: 0.400-8.001, p=0.447) where as being significant in univariate analysis (OR: 0.219; 95% CI: 0.087-0.552, p=0.001). Our findings suggest that the polymorphisms apo AI MspI and apo B EcoRI do not seem to affect CAD. But the genotype with E4 allele of apo E gene independent of other risk factors is associated with this disease.

Association of ApoAI gene rs12721026 polymorphism with cerebral hemorrhage in Changsha Han population and its effect on plasma lipid levels

To explore the association between apolipoprotein AI (ApoAI) gene rs12721026 polymorphism and cerebral hemorrhage (CH) in Changsha Han population, and to evaluate the effect of rs12721026 polymorphism on plasma lipid levels. A total of 273 patients with CH and 140 healthy controls were collected. The rs12721026 polymorphism of ApoAI was analyzed by SNaPshot genotyping analysis and DNA sequencing. The total cholesterol (TG), triglyceride (TC), HDL-C and LDL-C were examined by oxidase method. There was no significant difference in the genotype and allele frequencies of rs12721026 polymorphism between the CH group and the control group (P>0.05). Both in the CH group and in the control group, the level of HDL-C of the TT gene type of rs12721026 was significantly higher than that of the GT/GG gene type (P<0.05). There was no significant difference in the levels of TG, TC and LDL-C among different subgroups of gene types. There may be no association between apoAI gene rs12721026 polymorphism with CH in Changsha Han population, which may still influence the HDL-C levels.

Re-sequencing of the APOAI promoter region and the genetic association of the -75G &gt; A polymorphism with increased cholesterol and low density lipoprotein levels among a sample of the Kuwaiti population

BackgroundAPOAI, a member of the APOAI/CIII/IV/V gene cluster on chromosome 11q23-24, encodes a major protein component of HDL that has been associated with serum lipid levels. The aim of this study was to determine the genetic association of polymorphisms in the APOAI promoter region with plasma lipid levels in a cohort of healthy Kuwaiti volunteers.MethodsA 435 bp region of the APOAI promoter was analyzed by re-sequencing in 549 Kuwaiti samples. DNA was extracted from blood taken from 549 healthy Kuwaiti volunteers who had fasted for the previous 12 h. Univariate and multivariate analysis was used to determine allele association with serum lipid levels.ResultsThe target sequence included a partial segment of the promoter region, 5’UTR and exon 1 located between nucleotides −141 to +294 upstream of the APOAI gene on chromosome 11. No novel single nucleotide polymorphisms (SNPs) were observed. The sequences obtained were deposited with the NCBI GenBank with accession number [GenBank: JX438706]. The allelic frequencies for the three SNPs were as follows: APOAI rs670G = 0.807; rs5069C = 0.964; rs1799837G = 0.997 and found to be in HWE. A significant association (p < 0.05) was observed for the APOAI rs670 polymorphism with increased serum LDL-C. Multivariate analysis showed that APOAI rs670 was an independent predictive factor when controlling for age, sex and BMI for both LDL-C (OR: 1.66, p = 0.014) and TC (OR: 1.77, p = 0.006) levels.ConclusionThis study is the first to report sequence analysis of the APOAI promoter in an Arab population. The unexpected positive association found between the APOAI rs670 polymorphism and increased levels of LDL-C and TC may be due to linkage disequilibrium with other polymorphisms in candidate and neighboring genes known to be associated with lipid metabolism and transport.

PP118-SUN ASSOCIATION BETWEEN APOLIPOPROTEIN A-II (APOA2) POLYMORPHISM AND INSULIN RESISTANCE IN OBESE ADOLESCENTS

Rationale: The APOA2 gene has been associated with obesity and insulin resistance (IR) in previous studies with controversial results. This study aims to investigate association between a functional APOA2 promoter polymorphism ( 265T>C)) and IR and in a sample of Egyptian obese adolescents. Methods: Cross-sectional study was undertaken in 350 adolescents (207 females and 143 males), aged 17 19 years. They were 180 obese (BMI >P97) and 170 with normal weight, who participated in the project entitled “ Obesity among Youth: Lifestyle and Genetic Factors” funded by the Science and Technology Development Fund. Anthropometric, clinical and biochemical variables were determined. Homeostasis model assessment of IR (HOMAIR) was used. The study analyzed interactions between the APOA2 265T>C polymorphism and anthropometric measures and IR. Genotyping of 265T>C polymorphism was carried out using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis. Results: Prevalence of CC subjects ranged from 13% to 17%. Males and females were analyzed together because homogeneity of the effect was observed by sex. Homozygous individuals for the 265C allele had statistically higher BMI, waist to hip circumference, body fat percentage, visceral adipose tissue and HOMA-R level than in carriers of the T allele. Homozygous individuals for the 265C allele had higher obesity risk than carriers of the T allele. The mutant C allele of the APOA-II gene was more frequent in obese cases compared with normal weight cases in both sexes. Conclusion: The most consistent effects of the 265T>C polymorphism were observed on anthropometric variables and homozygous CC individuals had higher IR risk than carriers of the T allele in obese subjects.

Mutation mapping of apolipoprotein A-I structure assisted with the putative cholesterol recognition regions

Twenty-nine from 52 missense mutations in apoA-I gene are predicted to be deleterious by both SIFT and PolyPhen-2 algorithms. Among those, eight mutations with a prominent change in structure stability as modeled by the SDM tool for both lipid-free (Mei and Atkinson (2011) PDB ID: 3R2P) and HDL-bound (Wu et al. (2009) PDB ID: 3K2S) apoA-I, are referred as structural. The remaining mutations with a preferential location in a long intrinsically disordered region, predicted by the SPINE-D and DNdisorder tools, may influence the functional sites. Among structural mutations, five amyloidosis-only-related mutations, significant in a lipid-free structure, are located in 1–90 region. Six amyloidosis- and hypoalphalipoproteinemia-associated mutations, differently significant in two chains of lipid-bound apoA-I, are distributed among the N-domain. Six cholesterol recognition putative motifs (5 CRAC/1 CCM) in apoA-I structure are suggested to interact with cholesterol. Among those, the K40-W50 partially conserved CCM sequence with a putative recognition feature, predicted by the MoRF tool, may underlie cholesterol binding to lipid-free apoA-I, the binding triggering the disorder-to-order transition within MoRF. Thus, the impairment of helix formation and accelerated protein aggregation may underlie the amyloidogenic effect of W50R substitution. Also, D102H substitution in conserved CRAC2 V97-K106 sequence may be harmful in reverse cholesterol transport. With PDBe Motifs and Sites algorithm, cholesterol is a ligand for L101, F104 and W108 residues in HDL-bound apoA-I. The influence of specific mutation on apoA-I structure and mutated apolipoprotein switch between different pathologies is suggested to depend on the surrounding phase properties.

Abstract 412: In Silico Structural and Metabolic Profiling of Non-Synonymous Single Nucleotide Polymorphisms in APOA-I Gene

Mature apoA-I contains 243 residues organized in two-domains as N-terminal four-helix bundle and C-terminal two helices. Cholesterol interaction with both lipid-free and lipid-bound apoA-I may be one of the key events in amyloidosis and reverse cholesterol transport (RCT). By the SIFT score, 20 non-synonymous missense mutations in APOA-I gene, located almost exclusively in N-domain, may impair apoA-I function. A majority (4 from 5) of putative cholesterol recognition amino acid consensus (CRAC: L/V-X(1-5)-Y-X(1-5)-R/K) and a single cholesterol consensus motif (CCM: R/K-X(2-6)-I/L/V-X(3)-W/Y) aligned within/between helices in the bundle. Importantly, CRAC2 in apoA-I co-aligned with CRAC2 in apoE and CRAC4 in apoA-IV. A short four amino acid sequence L44-L47 may present disorder-to-order transitioning binding region in apoA-I as predicted by molecular recognition feature (MoRF). Indeed, CCM corresponded to unstructured region with low stability in lipid-free apoA-I. Stabilizing effect due to the direct cholesterol-peptide interaction with the involvement of CRAC1 (L14-K23) and/or CCM (K40-W50) in amyloidogenic peptide 1-93 is suggested to underlie the known effect of cholesterol on the induction of helix formation in this peptide. Cholesterol may be speculated to act in helix formation as a chemical chaperone thus triggering disorder-to-order transition within MoRF; without cholesterol, this MoRF may be involved into protein-protein interaction. Indeed, the association of W50R substitution with the accelerated mutant aggregation rate and the involvement of L44-S55 segment into cross-beta-sheet formation were demonstrated by others. Also, D102H substitution in CRAC2 (V97-K106) may be harmful in RCT. With PDBe Motifs and Sites algorithm, cholesterol is a ligand for L101, F104 and W108 residues in CRAC2 motif of apoA-I in nascent HDL. Besides, the resistance of two-domain apoA-I structure to denaturation by GuHCl is sensitive to cholesterol level in discoidal HDL. Overall, different CRACs may contribute into amyloidosis-connected apoA-I misfolding and cholesterol efflux for lipid-free apoA-I. Cholesterol binding to lipid-bound apolipoprotein may change the structural plasticity of two domains and/or their relative dimensions.

Validation of the Antidiabetic and Hypolipidemic Effects of Hawthorn by Assessment of Gluconeogenesis and Lipogenesis Related Genes and AMP-Activated Protein Kinase Phosphorylation

Since with the increased use of antidiabetic and antihyperlipidemic effect of phytonutrients for daily supplement has gained considerable attention worldwide, we examine the effect and molecular mechanism of Crataegus pinnatifida Bge. var. major N.E. Br. (hawthorn) by quantifying the expression of hepatic gluconeogenesis and lipogenesis on diabetes and dyslipidemia in high-fat (HF)-fed C57BL/6J mice. Firstly, mice were divided randomly into two groups: the control (CON) group was fed with a low-fat diet, whereas the experimental group was fed a 45% HF diet for 8 weeks. Afterwards, the CON group was treated with vehicle, whereas the HF group was subdivided into five groups and was given orally hawthorn extract (including 0.2, 0.5, 1.0 g/kg/day extracts) or rosiglitazone (Rosi) or vehicle for 4 weeks afterward. Diabetic mice showed an increase in plasma glucose and insulin. Glucose lowering was comparable with Rosi-treated mice. This study demonstrated that hawthorn was effective in ameliorating the HF diet-induced hyperglycemia, hypertriglyceridemia and hypercholesterolaemia. Hawthorn extract significantly increases the hepatic protein contents of AMP-activated protein kinase (AMPK) phosphorylation and reduces expression of phosphenol pyruvate carboxykinase (PEPCK) and glucose production. Furthermore, hawthorn decreased in hepatic triacylglycerol and cholesterol synthesis (including sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthase (FAS), SREBP2). An increase in expressions of apoA-I gene and high-density lipoprotein cholesterol (HDL-C) was detected in HF-fed mice treated with high dose hawthorn. Our data suggest that hawthorn extract are capable of decreasing glucose production and triacylglycerol synthesis by inducing AMPK-phosphorylation and hawthorn is a candidate source of antidiabetic and antihyperlipidemic phytonutrients factors.

Post-transcriptional nature of uremia-induced downregulation of hepatic apolipoprotein A-I production

Chronic kidney disease is associated with premature death from cardiovascular disease, which is, in part, driven by high density lipoprotein deficiency and dysfunction. One of the main causes of high density lipoprotein deficiency in chronic kidney disease is diminished plasma apolipoprotein (Apo)A-I level. Plasma ApoA-I is reduced in dialysis patients and hepatic ApoA-I messenger RNA (mRNA) is decreased in the uremic rats. This study explored the mechanism of uremia-induced downregulation of ApoA-I. Human hepatoma derived cells were incubated in media containing whole plasma or plasma subfractionation from normal subjects and patients with end stage renal disease pre- and posthemodialysis. Cells and culture media were isolated to measure ApoA-I protein and mRNA. ApoA-I promoter activity was measured using transfection with a luciferase promoter construct containing the -2096 to +293 segment of ApoA-I gene. Finally, effect of uremic and control plasma was assessed on ApoA-I RNA stability. Exposure to uremic plasma significantly reduced ApoA-I mRNA expression and ApoA-I protein production. These effects were reversed by replacing uremic plasma with normal plasma. Although no difference in ApoA-I promoter activity was found between cells exposed to uremic and normal plasma, uremic plasma significantly reduced ApoA-I RNA stability. Experiments using plasma subfractions revealed that the inhibitory effect of uremic plasma on ApoA-I mRNA expression resides in fractions containing molecules larger but not smaller than 30 kd. The pre- and postdialysis plasma exerted an equally potent inhibitory effect on ApoA-I mRNA abundance. Uremia lowers ApoA-I production by reducing its RNA stability. The inhibitory effect of uremic milieu on ApoA-I mRNA expression is mediated by non-dialyzable molecule(s) larger than 30 kd.

HDL deficiency due to a new insertion mutation (ApoA-INashua) and review of the literature

A 61-year-old white man of European ancestry with significant coronary heart disease since age 42 years and marked high-density lipoprotein (HDL) deficiency (HDL cholesterol 1 mg/dL) was evaluated. His fasting low-density lipoprotein cholesterol level was 42 mg/dL, and his triglycerides were 417 mg/dL on therapy with rosuvastatin 40 mg/day, ezetimibe 10 mg/day, fenofibrate 145 mg/day, and extended-release niacin 2 g/day. Further analysis of his plasma revealed an apolipoprotein (apo) A-I level of 23.5 mg/dL (approximately 20% of normal), and the absence of small alpha-4 HDL, medium alpha-3 HDL, and very large alpha-1 HDL, with only very small pre-beta-1 HDL and large alpha-2 HDL being present. APOA-I gene sequencing revealed a novel heterozygous in-frame insertion mutation with duplication of nucleotides 1535 through 1552 inserted at position 1553, causing a new amino acid glycine at codon 157 and a duplication of amino acids alanine, arginine, alanine, histidine, and leucine at codons 158-162. This novel apoA-I mutation results in the formation of apoA-I that appears to have abnormal lipid binding properties, resulting in impaired reverse cholesterol transport, probable enhanced clearance, and premature coronary heart disease.

HDL and Cardiovascular Risk

High-density lipoprotein cholesterol (HDL-C) has been dubbed the good cholesterol because it is thought to reflect the ability of HDL particles to remove excess cholesterol molecules from peripheral cells (including those in atherosclerotic plaques) for return to the liver. Not surprisingly, then, HDL-C has frequently been assumed to be a biomarker of HDL function, consistent with the inverse relationship in observational studies between plasma levels of HDL-C and risk of coronary artery disease. Recently, Voight et al have challenged this assumption by showing that genetically elevated HDL-C did not protect against myocardial infarction. This finding has fueled a lively discussion in the lay, scientific, and medical press about the relationship between HDL-C and HDL function, and the potential effectiveness of various HDL-C raising strategies.

Niacin increases HDL biogenesis by enhancing DR4-dependent transcription of ABCA1 and lipidation of apolipoprotein A-I in HepG2 cells

The lipidation of apoA-I in liver greatly influences HDL biogenesis and plasma HDL levels by stabilizing the secreted apoA-I. Niacin is the most effective lipid-regulating agent clinically available to raise HDL. This study was undertaken to identify regulatory mechanisms of niacin action in hepatic lipidation of apoA-I, a critical event involved in HDL biogenesis. In cultured human hepatocytes (HepG2), niacin increased: association of apoA-I with phospholipids and cholesterol by 46% and 23% respectively, formation of lipid-poor single apoA-I molecule-containing particles up to ~2.4-fold, and pre β 1 and α migrating HDL particles. Niacin dose-dependently stimulated the cell efflux of phospholipid and cholesterol and increased transcription of ABCA1 gene and ABCA1 protein. Mutated DR4, a binding site for nuclear factor liver X receptor alpha (LXR α ) in the ABCA1 promoter, abolished niacin stimulatory effect. Further, knocking down LXR α or ABCA1 by RNA interference eliminated niacin-stimulated apoA-I lipidation. Niacin treatment did not change apoA-I gene expression. The present data indicate that niacin increases apoA-I lipidation by enhancing lipid efflux through a DR4-dependent transcription of ABCA1 gene in HepG2 cells. A stimulatory role of niacin in early hepatic formation of HDL particles suggests a new mechanism that contributes to niacin action to increase the stability of newly synthesized circulating HDL.

Solid organ transplantation for non-TTR hereditary amyloidosis: report from the 1st International Workshop on the Hereditary Renal Amyloidoses

Fibrinogen A α-chain (AFib) and apolipoprotein AI (AApoAI) amyloidosis due to variants in the AFib and ApoAI genes are the most common types of hereditary amyloidosis in Europe and the United States. Liver is the exclusive source of the aberrant amyloidogenic protein in AFib and responsible for supplying approximately half of the circulating variant ApoAI. Nephrotic syndrome and renal impairment due to renal amyloidosis are common disease manifestations; however, recent research provides evidence to support a more diverse and systemic disease phenotype, which in turn has implications in the management of the hereditary amyloidoses with solid organ transplantation and, in particular, liver transplantation.

Functions of Monocyte Chemotactic Protein‐3 in Transgenic Mice Fed High‐fat Diet

In order to look into the function of the monocyte chemotactic protein‐3 (MCP‐3) in the atherogenesis, transgenic mice in which the MCP‐3 is over‐expressed in a specific tissue (vesicular endothelium) have been produced in the previous work, genotyped by a specific primer set designed from the MCP‐3 cDNA and fed high‐fat‐high‐cholesterol diet for 12 weeks to provide extreme atherogenic conditions. In the level of plasma lipids, the mice fed HFHC diet showed a higher level of total cholesterol and lower in the triglyceride level. On the other hand, the level of HDL‐cholesterol was surprisingly increased in the mice fed normal diet showing 72.6 in the HTR (HDL vs. total cholesterol ratio). Accordingly, the atherogenic index of the mice fed a normal diet was drastically lower than in the wild‐type mice. This was supported through a marked increase in the expression of Apo‐AI gene in the transgenic mice fed normal diet identified by microarray analysis. Activities of anti‐oxidant enzymes were also increased in the transgenic mice fed HFHC diet, indicating that there might be more oxidative damage to tissues of the mice fed HFHC diet leading to a progress toward the atherosclerosis. Supplementation of anti‐oxidants to the diet, naringin and hesperidin, was shown to lower the level of the activities of anti‐oxidant enzymes.

Coalition of DNA polymorphisms of ApoB and ApoAI genes is related with coronary artery disease in Kazaks

ObjectiveTo explore the relationship between polymorphisms of XbaI and MspI loci of apolipoprotein B (ApoB) gene and -75 bp, +83 bp loci of apolipoprotein AI (ApoAI) gene and coronary heart disease (CHD) in Kazaks of Xinjiang Uyghur Autonomous Region, China.MethodsThese loci were analyzed by PCR-restriction fragment length polymorphism (PCR-PFLP). Two hundred and five patients with CHD and two hundred and thirty six controls were involved.ResultsThere were significant distinctions among low-density lipoprotein cholesterol (LDL-C), triglyceride (TG) and the ApoAI/ApoB ratio between the two groups, but no significant distinction among the polymorphism frequencies of the four sites between the two groups. The polymorphism coalition frequency of X−−/Ms++/M1+−/M2++ (named Coalition 11) was significantly higher in CHD compared to the control group (14.6% vs. 7.2%, P < 0.05). The level of total cholesterol (TC) in Coalition 11 was significantly higher and the level of the ApoAI/ApoB ratio in Coalition 11 was significantly lower than Coalition 1∼10 in CHD patients. The level of the ApoAI/ApoB ratio of Coalition 11 was significantly lower than the Coalition 1∼10 in control group. The levels of ApoAI/ApoB ratio of Coalition 3 were significantly higher compared to Coalition 11 in the two groups, respectively. The level of LDL-C of Coalition 3 was significantly lower than in the Coalition 11 in control group. The level of TC of Coalition 5 was significantly higher than Coalition 3 in the CHD group. The level of the ApoAI/ApoB ratio of Coalition 5 was significantly lower than in Coalition 3 or Coalition 1∼10 of the two groups, respectively. The level of LDL-C of Coalition 5 was significantly higher than in Coalition 3 in control group. The ratio of ApoAI/ApoB was negatively related to TC, LDL-C and was positively related to HDL-C, both in CHD and control groups.ConclusionCoalition 11 of the 4 loci polymorphisms of the ApoB and ApoAI genes was correlated with CHD in Kazaks, and perhaps the ratio of ApoAI/ApoB was the most diagnostic parameter related with CHD among all lipid parameters. CHD may also be associated with Coalition 5, and, perhaps, Coalition 3 may have been confirmed as a protection factor against CHD, if more samples were enrolled.