The role of apolipoprotein A5 in obesity and the metabolic syndrome

Apolipoprotein A5 (apoA5) has an important role in lipid metabolism, specifically for triglyceride‐rich lipoproteins. Recently, evidence has emerged for an association between genetic variability at the APOA5 locus and increased risk of obesity and metabolic syndrome. However, its mechanism of action remains to be fully elucidated. Importantly, an intracellular role of apoA5 has been indicated since apoA5 is associated with cytoplasmic lipid droplets and affects intrahepatic triglyceride accumulation, as well as affecting intravascular triglyceride metabolism. Given that adipocytes provide the largest storage depot for energy in the form of triglyceride within the lipid droplets, and play a crucial role in the development of obesity, we highlight recent findings discussing the interaction of apoA5 with adipocytes or adipose tissue, indicating that apoA5 may act as a novel regulator to modulate triglyceride storage in adipocytes. We review the association of APOA5 gene polymorphisms with obesity and metabolic syndrome, and propose potential mechanisms by which apoA5 may increase susceptibility to these conditions. This review provides new insights into the physiological role of apoA5 and identifies a potential therapeutic target for obesity and associated disorders.     

Different associations of apoE gene polymorphism with metabolic syndrome in the Vojvodina Province (Serbia)

The metabolic syndrome (MetS) is a polygenic multifactorial metabolic disorder with strong socioeconomic influence. MetS has became a worldwide epidemic, that directly increases the risk of cardiovascular diseases and type 2 diabetes mellitus. The human apoE gene, coding Apolipoprotein E, has three common polymorphisms in human population: e2, e3 and e4, which are proved to be associated with impaired lipid metabolism. The contribution of apoE polymorphism to MetS disorders has not been investigated previously in Vojvodina Province, region with the highest number of obese people in Serbia. The aim of this study was to evaluate apoE gene polymorphism in relation to MetS disorders. The healthy control group of 30 individuals and 63 MetS patients were examined for apoE variants in relation to biochemical and anthropometric parameters. The genotypes were determined by PCR–RFLP. Regarding all parameters, significantly higher values were detected in MetS group compared to control. The MetS group of patients had significantly higher frequency of e4 allele. In addition, positive relation was revealed between e4 allele presence and all measured parameters. It was found that the e4 allele was related with a significantly increased OR of MetS disorders according to the International Diabetes Federation definition. These results suggested that e4 allele may act as a one of determinants for development of metabolic syndrome.     

脂代谢相关基因在apoE基因缺失幼龄小鼠肝脏中的表达

本文旨在分析脂代谢相关基因在载脂蛋白E(apolipoprotein E,apoE)基因缺失(apoE-/-)幼龄小鼠肝脏中的表达特征及其与血脂紊乱和动脉粥样硬化(atherosclerosis,AS)早期病变的关系.利用半定量RT-PCR和荧光实时定量RT-PCR技术,分析14 d龄、1、2和3月龄apoE-/-小鼠及同龄野生型(wild type,WT)小鼠肝脏脂代谢相关基因的表达,并进行血生化指标及主动脉病理形态学榆测.apo-/-小鼠肝脏中apoAI、apoAIV表达在14d龄时即发生显著变化(P<0.05);在1月龄时apoB10G表达较同龄WT小鼠明显上调(P＜0.05);apoA V表达则在2月龄时较同龄WT小鼠上调(P＜0.05),此时可观察到apoE-/-小鼠主动脉内膜出现AS早期病变;Faf/CD36和Angptl 3表达在3月龄时较同龄WT小鼠上调(P＜0.05);实验中检测的其它基因的mRNA表达与同龄WT小鼠相比无显著性差异.apoE-/-小鼠血清总胆同醇、甘油三酯、低密度脂蛋白胆固醇和高密度脂蛋白胆固醇含量均高于同龄WT小鼠,并随年龄增长而升高.apoE-/-小鼠和同龄WT小鼠血清中apoB100蛋白浓度在14 d龄到3月龄问变化趋势与其在肝脏中mRNA表达及血清中低密度脂蛋白胆崮醇含量变化趋势基本一致.上述部分脂代谢相关基因表达在幼龄小鼠即发生改变,与血脂紊乱以及主动脉AS病变发生发展过程呈正相关,说明其可能在幼龄小鼠脂质代谢紊乱发生过程中起重要作用,从而引起动脉内皮细胞功能改变乃至AS早期病变的发生.     

Analysis of MTNR1B gene polymorphisms in relationship with IRS2 gene variants,epicardial fat thickness,glucose homeostasis and cognitive performance in the elderly

Genome-wide association studies pinpointed common variants in or near the MTNR1B gene encoding MT2 melatonin receptor to be strongly associated with fasting glucose levels. IRS2 gene polymorphisms impact insulin resistance and epicardial fat (EF) thickness, which in turn is correlated with visceral adiposity, cognitive ability and risk for metabolic plus cardiovascular disease. We aimed to discover the interactions between MTNR1B and IRS2 gene polymorphisms, insulin sensitivity, EF thickness and cognitive performance in the elderly. In 60 subjects aged 60 years and older, we evaluated five single nucleotide polymorphisms (SNPs) within the MTNR1B locus (rs10830962, rs4753426, rs12804291, rs10830963, rs3781638), the Gly1057Asp variant of IRS2 gene (rs1805097), biochemical parameters, cognitive performance by the Mini Mental State Examination (MMSE) and EF thickness by transthoracic echocardiography. We found that MTNR1B and IRS2 gene variants impacted EF thickness, lipid profile and glucose homeostasis. IRS2 but not MTNR1B variants impacted MMSE scores. In conclusion, MTNR1B SNPs interact with IRS2 gene variant, correlate with the amount of epicardial adipose tissue and impact glucose homeostasis and lipid profile influencing cardiometabolic risk.     

Genetic association of apolipoprotein E with age-related macular degeneration.

Age-related macular degeneration (AMD) is the most common geriatric eye disorder leading to blindness and is characterized by degeneration of the neuroepithelium in the macular area of the eye. Apolipoprotein E (apoE), the major apolipoprotein of the CNS and an important regulator of cholesterol and lipid transport, appears to be associated with neurodegeneration. The apoE gene (APOE) polymorphism is a strong risk factor for various neurodegenerative diseases, and the apoE protein has been demonstrated in disease-associated lesions of these disorders. Hypothesizing that variants of APOE act as a potential risk factor for AMD, we performed a genetic-association study among 88 AMD cases and 901 controls derived from the population-based Rotterdam Study in the Netherlands. The APOE polymorphism showed a significant association with the risk for AMD; the APOE epsilon4 allele was associated with a decreased risk (odds ratio 0.43 [95% confidence interval 0.21-0. 88]), and the epsilon2 allele was associated with a slightly increased risk of AMD (odds ratio 1.5 [95% confidence interval 0.8-2. 82]). To investigate whether apoE is directly involved in the pathogenesis of AMD, we studied apoE immunoreactivity in 15 AMD and 10 control maculae and found that apoE staining was consistently present in the disease-associated deposits in AMD-maculae-that is, drusen and basal laminar deposit. Our results suggest that APOE is a susceptibility gene for AMD.     

CYP3A5 genotyping for assessing the efficacy of treatment with simvastatin and atorvastatin

In this work, we examined the impact of polymorphism in the cytochrome P450 (CYP) 3A5 gene, CYP3A5*1 (6986A > G, rs 776746), on the reduction in the lipid levels caused by simvastatin and atorvastatin. We studied 350 hyperlipidemic patients who received 10-40 mg of atorvastatin (n = 175) or simvastatin (n = 175) daily. Genotyping for CYP3A5 was done by PCR-RFLP analysis. Differences in the lipid profile before and after treatment were expressed as the % difference. The frequency of CYP3A5polymorphism was 13.4% for heterozygotes and 86.6% for homozygotes. Comparison of the responses to same dose of each drug showed that the highest % difference was associated with total cholesterol (TC) in subjects receiving atorvastatin 40 mg compared with simvastatin 40 mg (p = 0.048). However, comparison of the responses to equivalent doses of atorvastatin vs. simvastatin revealed no difference in the % change in any of the lipid parameters examined. In individuals with the same CYP3A5 genotype, a head to head comparison of the efficacy of the same dose of simvastatin vs. atorvastatin revealed an advantage for atorvastatin. For equivalent doses of atorvastatin vs. simvastatin there was no difference in the % change in any of the lipid parameters examined. Within the same genotype there was a significant difference in the % change related to the drug treatment.     

Apolipoprotein E gene polymorphism effects triglycerides but not CAD risk in Caucasian women younger than 65 years

The pathogenesis of CAD is similar in man and woman, yet some risk factors have a greater impact on the CAD risk in woman than in man. In this study we assessed the effect of the apoE gene polymorphism on lipid metabolism and risk for CAD in women younger than 65 years (premature CAD). In a cross-sectional case-control study, 147 female Caucasian patients with premature CAD (confirmed by coronarography) were compared with a control group of 114 healthy Caucasian women. The apoE allele frequencies of patients vs. controls were 5.1% vs. 5.7% for 2, 85.4% vs. 83.3% for 3, and 9.5% vs. 11% for epsilon4. The subjects with epsilon2/3 genotype had statistically significantly higher triglycerides levels than the subjects with epsilon3/3 genotype (2.23 +/- 2.13 mmol.L(-1) vs. 1.73 +/- 0.84 mmol.L(-1); p<0.05). Logistic regression analysis revealed no association between risk genotypes (3/4 and 4/4) of the apoE gene polymorphism and CAD risk (OR 0.9; 95% CI 0. 5-1.7, P=0.7). We observed metabolic clustering of diabetes mellitus, arterial hypertension, higher BMI and triglycerides, and lower HDL cholesterol in the CAD group compared to the control group. Arterial hypertension, diabetes, HDL cholesterol level, and BMI were independent risk factors for premature CAD in female population, whereas, the risk genotype of the apoE gene polymorphism was not. In conclusion, in Slovene women risk genotypes of the apoE gene polymorphism are not associated with premature CAD; a metabolic clustering of diabetes, HDL, triglycerides and arterial hypertension is frequently present in Caucasian women with premature CAD.     

Intracellular role of exchangeable apolipoproteins in energy homeostasis,obesity and non‐alcoholic fatty liver disease

Exchangeable apolipoproteins play an important role in systemic lipid metabolism, especially for lipoproteins with which they are associated. Recently, emerging evidence has suggested that exchangeable apolipoproteins, such as apolipoprotein A4 (apoA4), apolipoprotein A5 (apoA5), apolipoprotein C3 (apoC3) and apolipoprotein E (apoE), also exert important effects on intracellular lipid homeostasis. There is a close link between lipid metabolism in adipose tissue and liver because the latter behaves as the metabolic sensor of dysfunctional adipose tissue and is a main target of lipotoxicity. Given that the energy balance between these two major lipogenic organs is intimately involved in the pathogenesis of obesity and non‐alcoholic fatty liver disease (NAFLD), we here review recent findings concerning the intracellular function of exchangeable apolipoproteins in triglyceride metabolism in adipocytes and hepatocytes. These apolipoproteins may act as mediators of crosstalk between adipose tissue and liver, thus influencing development of obesity and hepatosteatosis. This review provides new insights into the physiological role of exchangeable apolipoproteins and identifies latent targets for therapeutic intervention of obesity and its related disorders.     

Ⅱ型糖尿病患者APOA5-1131T/C基因多态性与血脂代谢和胰岛素抵抗的关系研究

为了探讨载脂蛋白A5基因(APOA5)-1131T/C多态性在中国镇江地区的频率分布及其与血浆脂质代谢和Ⅱ型糖尿病患者胰岛素抵抗的关系, 采用聚合酶链反应-限制性片段长度多态性分析(PCR-RFLP)结合琼脂糖凝胶电泳技术检测152例健康人及71例Ⅱ型糖尿病患者APOA5 -1131T/C基因型及等位基因频率分布, 同时采用生化方法测定所有研究对象的血脂、血糖和胰岛素水平。结果显示: 糖尿病组APOA5 -1131C等位基因频率显著高于对照组(0.430 vs 0.296, P = 0.006)。CC纯合子患糖尿病的风险是TT纯合子的3.75倍(OR = 3.75, 95% CI: 1.57~8.92), 且经Logistic回归分析, 校正年龄、BMI和血浆HDL-c、LDL-c及ApoB水平等其他混杂因素影响后, 这种差异仍具有显著性意义(OR = 2.70, 95%CI: 1.24 ~ 5.86)。糖尿病组C等位基因携带者TG水平显著高于非C等位基因携带者(P < 0.01), TC水平和LDL-c水平亦明显升高(P < 0.05)。但是在两组中, 不同基因型患者 胰岛素抵抗相关指标均无显示差异。提示APOA5-1131T/C单核苷酸多态性对人群血浆TG水平有影响, -1131C等位基因与血浆TG、TC和LDL-c水平增高有关, 但是与糖尿病患者胰岛素相关指标无关; APOA5 -1131C等位基因可能与人群糖尿病的发生相关联。     

SOD2 gene polymorphism and response of oxidative stress parameters in young wrestlers to a three-month training

The aim of the study was to analyse the effect of Val 16Ala polymorphism in SOD2 gene on oxidative stress parameters and lipid profile of the blood during a three-month wrestling training. The study included 53 Polish young wrestlers. Blood samples were collected at the beginning of the programme and following three months of the training. The list of analysed parameters included erythrocyte and serum activities of superoxide dismutase (SOD), whole blood glutathione peroxidase (GPx) activity, total glutathione (tGSH) level, concentration of lipid hydroperoxides (LHs), total antioxidant capacity (TAC) and creatine kinase (CK) activity in the serum, as well as lipid profile parameters: triglycerides (TG), total cholesterol (TC), high-density (HDL-C), and low-density lipoprotein cholesterol (LDL-C). Three-month training resulted in a decrease in CK activity, an increase in serum SOD activity, as well as in unfavourable changes in serum lipid profile: an increase in TC, LDL-C, and TG, and a decrease in HDL-C. Aside from CK activity, all these changes seemed to be associated with presence of Val allele. Prior to the training programme, subjects with Ala/Ala genotype presented with lower levels of LHs, lower whole blood GPx activity, and lower serum concentrations of TC than the individuals with Ala/Val genotype. Both prior to and after three-month training, higher levels of tGSH were observed in Val/Val genotype as compared to Ala/Val genotype carriers. Moreover, multiple regression analysis demonstrated that SOD2 genotype was a significant predictor of pre-training whole blood GPx activity and erythrocyte SOD activity (Val/Val?>?Ala/Val?>?Ala/Ala). Altogether, these findings suggest that Val 16Ala polymorphism in SOD2 gene contributes to individual variability in oxidative stress status and lipid profile of the blood in young wrestlers, and may modulate biochemical response to training.     

ApoE genotyping and response to galanthamine in Alzheimer's disease--a real life retrospective study

This study was undertaken to evaluate the effect of galanthamine, a new cholinesterase inhibitor on cognitive performances in 84 patients with various apoE genotype and Alzheimer's disease (AD) during the six-month treatment. The diagnosis of AD was made on the basis of NINCDS/ADRDN criteria. ApoE4 genotype was determined by PCR procedure. The cognitive performance was assessed MMSE at baseline and six months later. The difference among the groups was statistically analyzed by ANOVA model and Pearson's chi2-test. The MMSE at baseline in all completes was 18.0 +/- 3.73, whereas the mean value of MMSE after 6 months was 16.4 +/- 5.61 indicating significant deterioration (p < 0.01). Of the 84 patients, 14 (169%) were apoE4 homozygous, 41 (49%) were heterozygous, whereas 29 (35%) were apoE4 negative. The significant number of responders was observed among apoE4 homozygous patients (71%; chi2 = 6.89; p = 0.032). The subgroup of apoE4 homozygous patients with AD in its mild to moderate stage may be considered as responders to galanthamine.     

Rare variant of apolipoprotein E (Arg136 -->Ser) in two normolipidemic individuals

Through the analysis of the common apolipoprotein (apo) E gene polymorphism in large Caucasian population study with the PCR and subsequent restriction analysis, we have identified carriers of mutant allele Arg136-->Ser. Both of them (71-years-old female and her 43-years-old son) have normal lipid parameters. We suggest that Arg136-->Ser mutation in apoE is not necessarily connected with elevated lipid levels in all cases. Furthermore, so far unidentified factors (environmental and/or genetic) are important for the development of lipid metabolism disorders in apoE Arg136-->Ser mutation carriers.     

Genotype and allele frequency of PAI-1 promoter polymorphism in healthy subjects from the west of Mexico. Association with biochemical and hematological parameters

We investigated the genotype and allelic frequency of the -675 bp insertion/deletion polymorphism at the PAI-1 gene promoter, in healthy Mexican subjects. It was compared to the lipid profile and hematological parameters, and to other healthy worldwide populations. A Mexican population sample of 110 individuals was studied. Demographic data and clinical characteristics of the subjects were registered. Fasting lipid profile, serum glucose, fibrinogen, hematological parameters and leukocyte genomic DNA isolation from peripheral blood were performed in all the participants. Screening of the PAI-1 genotype was done by PCR and restriction analysis. Genotype 4G/4G, 4G/5G, 5G/5G frequency in Mexican healthy subjects was: 14.55%, 39.09%, 46.36%, respectively, whereas the allelic frequency for 5G allele was 65.9%. A significant lesser frequency for 4G allele and related genotypes (4G/4G and 4G/5G) was established in healthy subjects from Mexico, respect to all the compared populations. A particular genotype and allelic frequency of this PAI-1 polymorphism was established in Mexico. The clinical parameters were not associated according to each genotype of PAI-1.     

血清脂联素与载脂蛋白A5 及2 型糖尿病的关系

目的:检测血清脂联素(APN)水平,分析血清APN浓度与血脂、血清载脂蛋白A5(apoA5)及2型糖尿病的关系。方法:收集2型糖尿病(T2DM)210例,健康体检者112例,采用ELISA法检测血浆脂联素水平,双抗体夹心ELISA法检测血清载脂蛋白A5(apoA5)水平,7600-020E全自动生化分析仪检测总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C)等,放射免疫分析仪检测血胰岛素水平。结果:T2DM患者血清APN浓度明显低于健康对照组,LDL-C、TG及TC均高于对照组(P<0.05)。T2DM患者血清apoA5浓度(200.3±51.2)ng/ml,显著低于健康对照组(229.8±56.5)ng/ml,P<0.05。Pearson相关分析显示经年龄、性别校正后APN水平与LDL-C、TG呈负相关,与HDL-C呈正相关;T2DM组APN与apoA5呈正相关(P<0.05)。结论:T2DM患者血清APN水平显著降低,本研究证实低水平血清APN和apoA5不仅与血脂代谢密切相关,还可作为T2DM患者早期监测的指标,对其预后评价具有积极的意义。     

Association of lipoprotein lipase and apolipoprotein C-III genes polymorphism with acute myocardial infarction in diabetic patients

Lipoprotein lipase (LPL) and Apolipoprotein C-III (APOC-III) play an important role in lipid metabolism. The aim of this study was to explore the possible associations of the gene polymorphisms (LPL HindIII, LPL Ser(447)-Ter and APOC3 SstI), diabetes mellitus, and plasma lipids with myocardial infarction. The polymorphisms were assessed by restriction assay in 200 Egyptian MI patients (100 diabetic and 100 non-diabetic) and 100 healthy controls. This study demonstrated that individuals with the H2H2 genotype or S2 allele have more than three times higher relative risk of suffering from MI than those carrying the H1H1 or S1S1. Type 2 DM mainly lowers HDL-C levels in MI patients who carry H2H2 or S2S2 genotype and increases TC, TG, and LDL levels in MI patients carrying H2H2 or S2S2 genotype compared with non-diabetic MI patients carrying the same genotypes. In S447X polymorphism, it was observed that DM led to loss of the protective lipid profile in MI patients carrying 447XX genotype. These findings suggest that H2H2 or S2S2 genotypes are associated with dyslipidemia and increased risk of myocardial infarction. The S447X polymorphism is associated with a favorable lipid profile. However, the association of diabetes mellitus with these polymorphisms leads to unfavorable lipid profile.     

Apolipoprotein A-IV polymorphism and its effect on plasma lipid and apolipoprotein concentrations

Recently, we determined the apolipoprotein E (apoE) phenotype distribution in 2,000 randomly selected 35-year-old male individuals by slab gel isoelectric focusing of delipidated plasma samples, followed by immunoblotting using anti-apoE antiserum. These blots have been successfully re-used for immunovisualization of apoA-IV isoelectric focusing patterns. In a population sample of 1,393 individuals, four distinct apoA-IV isoforms were detected, encoded by the alleles A-IV*0, A-IV*1, A-IV*2, and A-IV*3 with gene frequencies of 0.002, 0.901, 0.079, and 0.018, respectively. The mean of plasma cholesterol, triglyceride, apoB and E levels did not differ significantly among the different apoA-IV phenotype groups. For these lipoprotein parameters, less than 0.1% of the total phenotypic variance could be accounted for by the APOA-IV gene locus. Our results did not show any effect of apoA-IV polymorphism on plasma apoA-I levels nor could we find any correlation between plasma levels of apoA-I and apoA-IV within the different apoA-IV phenotype groups. The plasma level of apoA-IV in subjects bearing the A-IV*3 allele is significantly lower than in subjects without the A-IV*3 allele (5 mg/dl versus 14 mg/dl). We therefore conclude that, in contrast to the apoE polymorphism, the polymorphism at the APOA-IV locus does not influence any of the levels of the lipoprotein parameters considered except apoA-IV.     

Association of apolipoprotein B XbaI gene polymorphism and lipid profile in northern Indian obese

BACKGROUND:

Over the last few decades, obesity, diabetes, and hypertension have become main health evils. The health problems of obesity are well-recognized. However, the fact that all obese individuals are not at the same risk of developing a disease is also recognized. The apolipoprotein B (APOB) plays a central role in lipid metabolism. So we compare the association of APOB XbaI gene polymorphism and lipid profile total in obese north Indian population.

MATERIALS AND METHODS:

A total of 132 obese (body mass index [BMI] >25 kg/m²) and 132 age matched non-obese (BMI ≤ 25 kg/m²) subjects were studied after taking detailed clinical profile. Lipid profile in serum/plasma was done using commercial kits. Genetic analysis of APOB XbaI was done using Polymerase Chain Reaction-Restriction Fragment Leanth polymorphism (PCR-RFLP).

STATISTICAL ANALYSIS:

Statistical analysis was performed by Statistical Package for the Social Sciences (SPSS) (version 11.5) software (IBM Corporation). All continuous variables were expressed as mean ± SD and tested by analysis of variance test. Comparisons of categorical variables were assessed using χ² tests or Fisher''s exact test. P < 0.05 was considered as significant.

RESULTS:

Analysis showed that obese subjects had significantly higher value of the waist-to-hip ratio, blood pressure (systolic and diastolic), and lipid profile. In APOB XbaI gene polymorphism, we did not find significant differences in genotype or allele frequencies. Moreover, none of the studied metabolic parameters (lipid profile) showed any association with the gene polymorphism.

CONCLUSIONS:

Study reveals no considerable association of APOB XbaI gene polymorphism with obesity and lipid profile in north Indians.     

Co-immunoprecipitation with Tau Isoform-specific Antibodies Reveals Distinct Protein Interactions and Highlights a Putative Role for 2N Tau in Disease

Alternative splicing generates multiple isoforms of the microtubule-associated protein Tau, but little is known about their specific function. In the adult mouse brain, three Tau isoforms are expressed that contain either 0, 1, or 2 N-terminal inserts (0N, 1N, and 2N). We generated Tau isoform-specific antibodies and performed co-immunoprecipitations followed by tandem mass tag multiplexed quantitative mass spectrometry. We identified novel Tau-interacting proteins of which one-half comprised membrane-bound proteins, localized to the plasma membrane, mitochondria, and other organelles. Tau was also found to interact with proteins involved in presynaptic signal transduction. MetaCore analysis revealed one major Tau interaction cluster that contained 33 Tau pulldown proteins. To explore the pathways in which these proteins are involved, we conducted an ingenuity pathway analysis that revealed two significant overlapping pathways, “cell-to-cell signaling and interaction” and “neurological disease.” The functional enrichment tool DAVID showed that in particular the 2N Tau-interacting proteins were specifically associated with neurological disease. Finally, for a subset of Tau interactions (apolipoprotein A1 (apoA1), apoE, mitochondrial creatine kinase U-type, β-synuclein, synaptogyrin-3, synaptophysin, syntaxin 1B, synaptotagmin, and synapsin 1), we performed reverse co-immunoprecipitations, confirming the preferential interaction of specific isoforms. For example, apoA1 displayed a 5-fold preference for the interaction with 2N, whereas β-synuclein showed preference for 0N. Remarkably, a reverse immunoprecipitation with apoA1 detected only the 2N isoform. This highlights distinct protein interactions of the different Tau isoforms, suggesting that they execute different functions in brain tissue.     

Apolipoprotein A5 internalized by human adipocytes modulates cellular triglyceride content

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

Association of the insulin-like growth factor II (IGF2) gene with human cognitive functions

Active search for candidate genes whose polymorphisms are associated with human cognitive functions has been in progress in the past years. The study focused on the role that the insulin-like growth factor II (IGF2) gene may play in the variation of cognitive processes related to executive functions. The ApaI polymorphism of the IGF2 gene was tested for association with selective attention during visual search, working memory/mental control, and semantic verbal fluency in a group of 182 healthy individuals. The ApaI polymorphism was associated with the general cognitive index and selective attention measure. Carriers of genotype AA displayed higher values of the two parameters than carriers of genotype GG. It was assumed that the ApaI polymorphism of the IGF2 gene influences the human cognitive functions, acting possibly via modulation of the IGF-II level in the central nervous system.