Apo E gene polymorphism on development of diabetic nephropathy

Type 2 diabetes causes premature morbidity and mortality due to the complications of atherosclerosis and diabetic nephropathy (DN). Polymorphism of Apo E gene is known to influence lipid metabolism. Apo E is polymorphic, consisting of three common isoforms (epsilon2, epsilon3 and epsilon4) encoded by three alleles (2, 3 and 4) in exon 4 on chromosome 19. The aim of this study was to investigate the effect of Apo E polymorphism as a prognostic risk factor for the development of DN. A total of 108 NIDDM patients were recruited from the Nephrology and Endocrinology Departments of our hospital. All subjects were divided into three groups: Group I: diabetes with nephropathy (n:37), group II: diabetes without nephropathy (n:71), group III: controls (n:46). Apo E genotypes were determined by real-time PCR. The epsilon4 allele frequency was significantly higher in-group I (10.8%) than in-group III (2.2%), (p < 0.05). In diabetics without nephropathy, the total cholesterol and LDL cholesterol levels were significantly lower in subjects with epsilon2 alleles than epsilon3 and epsilon4 alleles. In conclusion, the present prospective study indicates that the epsilon4 allele of the Apo E polymorphism is one of the prognostic risk factors involved in the development of DN with type 2 diabetes mellitus.     

Effects of physical activity on the progression of diabetic nephropathy: a meta-analysis

Background: Diabetic nephropathy (DN) is an important microvascular complication of diabetes. Physical activity (PA) is part of a healthy lifestyle for diabetic patients; however, the role of PA in DN has not been clarified. Our aim was to conduct a meta-analysis to explore the association between PA and DN risk.Methods: PubMed, Embase, Cochrane Library and Web of Science were systematically searched for articles examining PA in diabetic patients and its effect on renal function. Standardized mean differences (SMDs) and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. The study protocol is registered with PROSPERO (CRD42020191379).Results: A total of 38991 participants were identified from 18 studies. The results indicated that PA was associated with increases in the glomerular filtration rate (SMD = 0.01, 95% CI = [0.02–0.17]) and decreases in the urinary albumin creatinine ratio (SMD = −0.53, 95% CI: −0.72 to −0.34), rate of microalbuminuria (OR = 0.61, 95% CI = [0.46–0.81]), rate of acute kidney injury (OR = 0.02, 95% CI = [0.01–0.04]), rate of renal failure (OR = 0.71, 95% CI = [0.52–0.97]) and risk of DN in patients with Type 1 diabetes (OR = 0.67, 95% CI = [0.51–0.89]).Conclusions: This meta-analysis indicated that PA is effective for improving DN and slowing its progression; however, more high-quality randomized controlled trials are required on this topic.     

Relationship between five GLUT1 gene single nucleotide polymorphisms and diabetic nephropathy: a systematic review and meta-analysis

So far, case-control studies on the association between glucose transporter 1 (GLUT1) gene single nucleotide polymorphisms (SNPs) and diabetic nephropathy (DN) have generated considerable controversy. To clarify the linkage of GLUT1 SNPs on the risk of DN, a systematic review and meta-analysis was performed. A comprehensive literature search of electronic databases was conducted to obtain relative studies. Nine case-control studies were included. Significant differences were found between XbaI SNP (rs841853) and increased risk of DN in all genetic models. Subgroup analyses for Caucasians population and DN from both type 1 and type 2 diabetes also revealed positive results. For Enh2-1 SNP (rs841847), Enh2-2 SNP (rs841848) and HaeIII SNP (rs1385129), obvious linkages were demonstrated in recessive model. However, analysis for the association between HpyCH4V SNP (rs710218) and the susceptibility of DN showed no significance. Likewise, negative outcome was also found in the assessment for the influence of XbaI or Enh2-2 SNP on the pathogenesis progress of DN. The evidence currently available shows that XbaI, Enh2 and HaeIII SNPs, but not HpyCH4V SNP, in GLUT1 gene may be genetic susceptibility to DN. However, data does not support the association between either XbaI or Enh2-2 SNP and the severity of DN.     

Association between apolipoprotein E gene polymorphism and the risk of multiple sclerosis: A meta-analysis of 6977 subjects

Epidemiological studies have evaluated the association between apolipoprotein E (ApoE) gene polymorphism and multiple sclerosis (MS) risk. However, the results remain conflicting. Therefore, in order to derive a more precise association of ApoE gene polymorphism with MS risk, we performed this meta-analysis. Systematic searches of electronic databases PubMed, Embase and Web of Science, as well as hand searching of the references of identified articles were performed. Twenty studies were identified, covering a total of 4080 MS cases and 2897 controls. The results showed evidence for significant association between ApoE ε2 mutation and MS risk (for ε2/ε4 versus ε3/ε3: OR = 1.74, 95% CI = 1.12–2.71, p = 0.01; for ε2 allele versus ε3 allele: OR = 1.16, 95% CI = 1.01–1.35, p = 0.04). In the subgroup analysis by ethnicity, the similar results were obtained among Europeans (for ε2/ε4 versus ε3/ε3: OR = 1.81, 95% CI = 1.14–2.87, p = 0.01; for ε2 allele versus ε3 allele: OR = 1.19, 95% CI = 1.02–1.38, p = 0.03). After excluding the outlier studies by observing Galbraith plot, marginal association was found between ApoE ε3/ε4 genotype and the protective factor for MS (for ε3/ε4 versus ε3/ε3: OR = 0.86, 95% CI = 0.75–0.99, p = 0.04). In summary, the present meta-analysis provides evidence that ApoE ε2 mutation is associated with MS risk. In addition, ApoE ε3/ε4 genotype appears to be a protective factor for MS.     

Association between two genetic polymorphisms of the renin-angiotensin-aldosterone system and diabetic nephropathy: a meta-analysis

The widely studied candidate genes of the renin-angiotensin-aldosterone system, angiotensinogen (AGT), and angiotensin II receptor type 1 (AGTR1), are implicated in the development of diabetic nephropathy (DN). A number of studies have evaluated the association between the functional polymorphisms, AGT M235T and AGTR1 A1166C, and DN risk with conflicting results. The present meta-analysis was performed to estimate the overall risk of these polymorphisms associated with DN on 4,377 DN cases and 4,905 controls from 34 published case–control studies by searching electronic databases and reference lists of relevant articles. We examined the association between each polymorphism and the risk of DN by odds ratio (OR) with 95% confidence intervals (95% CI) and calculated the ORs for different genetic model. In addition, stratification analysis by ethnicity and diabetes mellitus (DM) type was conducted. In this meta-analysis, we failed to find any significant main effects in both overall analysis and stratified analysis for the AGT M235T. However, the overall analysis detected a significant association between the AGTR1 A1166C and the risk of DN for the CC compared with the AA and dominant genetic model (CC vs. AA: OR = 2.10, 95% CI: 1.00–4.44; dominant model: OR = 2.11, 95% CI: 1.06–4.23). In subgroup analysis, only patients with T2DM showed significant association for CC vs. AA model and dominant model (CC vs. AA: OR = 3.31, 95% CI: 1.21–9.08; dominant model: OR = 3.50, 95% CI: 1.41–8.69). This study suggests that the AGTR1 A1166C polymorphism may contribute to DN development, particularly in T2DM patients.     

Familial apolipoprotein E deficiency and type III hyperlipoproteinemia due to a premature stop codon in the apolipoprotein E gene.

A kindred with apolipoprotein E deficiency and a truncated lower molecular weight apoE mutant, designated apoE-3Washington, has been identified. Gel electrophoresis demonstrated complete absence of the normal apoE isoproteins and the presence of a small quantity of a lower molecular weight apoE. Plasma apoE levels in the proband were approximately 4% of normal. This marked deficiency of apoE resulted in delayed uptake of chylomicron and very low density lipoprotein (VLDL) remnants by the liver, elevated plasma cholesterol levels, mild hypertriglyceridemia, and the development of type III hyperlipoproteinemia. Sequence analysis of the patient's apoE gene revealed a single nucleotide substitution of an A for a G, which converted amino acid 210 of the mature protein, tryptophan (TGG), to a premature chain termination codon (TAG), thus leading to the synthesis of a truncated E apolipoprotein of 209 amino acids with a molecular mass of 23.88 kDa. Northern blot analysis of differentiated monocyte-derived macrophages demonstrated a mutant mRNA indistinguishable in size from normal apoE mRNA. The nucleotide substitution also resulted in the formation of a new restriction site for Mae I. Using this enzyme we were able to establish that the proband is a homozygote and that her two offsprings are heterozygous for the epsilon-3Washington allele. These data demonstrate that the striking deficiency of apoE-3Washington results in a moderate form of type III hyperlipoproteinemia. The clinical presentation also suggests a dispensable role of apoE in the nervous system and in immunoregulation.     

Identification of human apolipoprotein E variant gene: apolipoprotein E7 (Glu244,245----Lys244,245)

Apolipoprotein E (apoE) is one of the protein moieties of the human serum lipoproteins. Three major isoforms of apoE (apoE2, apoE3, and apoE4) and minor variant isoforms (apoE1, apoE5, and apoE7) have been detected by isoelectric focusing. In this study we have cloned the apoE7 gene from a patient with the apoE3/E7 phenotype associated with hypertriglyceridemia and diabetes mellitus. DNA sequencing revealed that the apoE7 gene has two base substitutions (G----A) changing Glu244,245----Lys244,245, compared with the apoE3 gene. The replacement of the two amino acids is consistent with the result of isoelectric focusing of the apoE7 isoprotein, which shifts to four positively charged units compared with the apoE3 isoprotein.     

Two copies of the human apolipoprotein C-I gene are linked closely to the apolipoprotein E gene

The gene for human apolipoprotein (apo) C-I was selected from human genomic cosmid and lambda libraries. Restriction endonuclease analysis showed that the gene for apoC-I is located 5.5 kilobases downstream of the gene for apoE. A copy of the apoC-I gene, apoC-I', is located 7.5 kilobases downstream of the apoC-I gene. Both genes contain four exons and three introns; the apoC-I gene is 4653 base pairs long, the apoC-I' gene 4387 base pairs. In each gene, the first intron is located 20 nucleotides upstream from the translation start signal; the second intron, within the codon of Gly-7 of the signal peptide region; and the third intron, within the codon for Arg39 of the mature plasma protein coding region. The upstream apoC-I gene encodes the known apoC-I plasma protein and differs from the downstream apoC-I' gene in about 9% of the exon nucleotide positions. The most important difference between the exons results in a change in the codon for Gln-2 of the signal peptide region, which introduces a translation stop signal in the downstream gene. Major sequence differences are found in the second and third introns of the apoC-I and apoC-I' genes, which contain 9 and 7.5 copies, respectively, of Alu family sequences. The apoC-I gene is expressed primarily in the liver, and it is activated when monocytes differentiate into macrophages. In contrast, no mRNA product of the apoC-I' gene can be detected in any tissue, suggesting that it may be a pseudogene. The similar structures and the proximity of the apoE and apoC-I genes suggest that they are derived from a common ancestor. Furthermore, they may be considered to be constituents of a family of seven apolipoprotein genes (apoE, -C-I, -C-II, -C-III, -A-I, -A-II, and -A-IV) that have a common evolutionary origin.     

Structure and expression of mouse apolipoprotein E gene

The mouse apolipoprotein E gene was isolated from a genomic library by screening with a cDNA probe. DNA including apolipoprotein E gene plus segments 2.5 kilobases upstream and 0.3 kilobase downstream of the coding region was transfected into NIH3T3 cells. The cells expressed the same-size apolipoprotein E mRNA and protein as those produced by mouse endogenously. The nucleotide sequence of the gene plus 5' and 3' flanking regions (one kilobase each) was determined. The sequence of the mouse apoliprotein E gene was highly homologous to that of the rat gene, not only in the coding regions but also in the non-coding and intron regions. The mouse and the human apolipoprotein E genes were homologous in the 5' proximal flanking region up to about 200 nucleotides as well as in the four exons. This proximal region was highly conserved for the genes of mouse, rat and human; the relative positions of the "TATA box" and the two copies of "GC box" were identical.     

Isolation and genetic characterization of the porcine apolipoprotein E gene

The present report describes the isolation and genetic characterization of the porcine apolipoprotein E (ape-E) gene. A single positive recombinant phage clone containing a 10·7-kb insert was isolated from a porcine genomic library, and a 4·2-kb fragment was subcloned and sequenced. The 4·2-kb fragment contained the entire apo-E gene in addition to upstream and downstream sequences (GenBank accession no. 470240). The porcine apo-E gene is made up of four exons and three introns, and encodes a preapo-E protein comprised of a signal peptide of 18 amino acids and a mature protein of 299 amino acids. The porcine apo-E gene contains a (CG)₁₃ microsatellite marker within intron three. This microsatellite is moderately polymorphic, and at least four alleles were evident at this locus among 10 animals from each of the Yorkshire, Hampshire, Landrace and Duroc breeds. Finally, localization of the porcine apo-E gene to chromosome 6 band q2·1 was determined by fluorescent in situ hybridization and confirmed by genetic linkage analysis.     

Dispersal and species diversity: a meta-analysis

Species diversity in communities of interacting organisms is thought to be enhanced by dispersal, yet mechanisms predicting this have little to say about what effects differing rates of dispersal have on diversity and how dispersal affects diversity at larger spatial scales. I performed meta‐analyses on 23 studies comprising 50 experiments that manipulated species migration and measured community richness or diversity to test three hypotheses: that dispersal increases local diversity; that this effect depends on the rate of dispersal, specifically, that local diversity should be maximized at intermediate dispersal rates or else linearly related to dispersal rate; and that regional diversity may be either unaffected or negatively impacted by dispersal because dispersal tends to homogenize local communities. I found that immigration increased local diversity. Further, in animal studies, diversity appears maximized at intermediate dispersal rates but not with plant studies; however, more standardized studies are needed. Finally, results are ambiguous as to what happens at larger scales, with studies finding either declines or no change in regional diversity with dispersal. Taken together, these results reveal that dispersal has a complex, spatially contingent relationship with patterns of species diversity.     

Hypomorphic apolipoprotein E mice: a new model of conditional gene repair to examine apolipoprotein E-mediated metabolism.

In creating an allelic variant of mouse Apoe designed to resemble human apolipoprotein E4 (apoE4), we generated hypomorphic apoE (hypoE) mice that express only approximately 5% of normal apoE mRNA levels in all tissues. Insertion of a neo cassette flanked by loxP sites in the third intron of Apoe reduced expression of the Arg-61 allelic variant in hypoE mice and resulted in plasma apoE levels that were approximately 2-5% of normal. Unlike other mouse models with low levels of circulating apoE, hypoE mice had a nearly normal lipoprotein cholesterol profile when fed a chow diet. Further reduction of apoE expression in hypoE/Apoe(-/-) heterozygous mice led to an increase in remnant lipoprotein-associated cholesterol levels, demonstrating that hypoE mice express close to the threshold level of Arg-61 apoE required for a normal lipoprotein profile. Unlike wild type mice, hypoE mice were susceptible to diet-induced hypercholesterolemia, which was fully reversed within 3 weeks after resumption of a chow diet. In Mx1-Cre transgenic hypoE mice, plasma apoE levels returned to normal within 10 days after gene repair and removal of the neo cassette following induction of Cre recombinase. HypoE mice provide the opportunity for conditional gene repair by crossing with inducible or lineage/cell type-specific Cre transgenic mice, generating new models to dissect the roles of apoE in atherosclerosis regression, immunoregulation, and neurodegeneration.     

Genetic association between the apolipoprotein E (ApoE) gene alleles and various forms of Alzheimer's disease]

Allele epsilon 4 of the apolipoprotein E (APOE) gene is associated with higher risk of Alzheimer's disease (AD) in many, though not all, ethnic groups. The APOE allele and genotype frequency distributions were studied in 207 AD patients without cerebrovascular disorders, 62 AD patients with cerebrovascular disorders (combined AD), and 206 control individuals (ethnic Russians from the Russian population). The frequency of allele epsilon 4 in patients with early-onset and late-onset AD was three times higher than in control individuals (p < 0.000001). Compared with control people, patients with cerebrovascular disorders displayed a twofold higher frequency of allele epsilon 4; the difference between the two groups was significant (p = 0.0019). Relative risk of AD in carriers of allele epsilon 4 was five times higher than in carriers of alleles epsilon 2 and epsilon 3 (p < 0.000001). Allele epsilon 2 had a protective effect with respect to AD onset until 65 years of age (p = 0.015). Thus, APOE allele epsilon 4 proved to be a universal factor of early-onset, late-onset, and combined AD in ethnic Russians from Russia.     

Isolation and characterisation of a variant allele of the gene for human apolipoprotein E

Size-selected human DNA fragments enriched in the Apolipoprotein E (ApoE) gene sequence were cloned from an individual of known ApoE phenotype, E2/E2. The clone bank was screened using a human cDNA clone for the ApoE locus (1), and a single genomic clone was isolated. Sequence data obtained from appropriate subcloned fragments confirmed that the codon for Arg-158 (CGC) in the E3 allele is altered to the codon for Cys (TGC) in the E2 allele. Hybridisation data indicated the presence of at least one intron in the ApoE gene, consistent with the structure of an independently isolated human ApoE4 allele (2).     

Analysis of apolipoprotein E7 (apolipoprotein E-Suita) gene from a patient with hyperlipoproteinemia

We have isolated and analyzed apolipoprotein E7 gene from a patient with hyperlipoproteinemia. Apolipoprotein E7 (apolipoprotein E-Suita) is a variant of apolipoprotein E with four additional units of positive charge compared to apolipoprotein E3, which is the major isoform of apolipoprotein E. The heterozygous gene of apolipoprotein E7/3 from the patient was cloned into lambda phage. The cloned apolipoprotein E genes were subcloned into a murine retrovirus shuttle vector and were expressed. Two out of five clones expressed apolipoprotein E7. The analysis of the nucleotide sequence of the exon and exon-intron boundary regions has shown two G-to-A nucleotide substitutions in the 548 and 551 nucleotide positions from the 5'-end of the fourth exon. These two base substitutions change the amino acid residues -Glu-Glu- to -Lys-Lys- at the 244 and 245 positions from the amino-terminus of the mature protein, and give four additional units of positive charge to the molecule.     

Analysis of apolipoprotein E5 gene from a patient with hyperlipoproteinemia

We have isolated and analyzed apolipoprotein E5 gene from a patient with hyperlipoproteinemia. Apolipoprotein E5 is a variant of apolipoprotein E with two additional units of positive charge and smaller apparent molecular weight than apolipoprotein E3, which is the major isoform of apolipoprotein E. The heterozygous gene of apolipoprotein E5/3 from the patient was cloned into lambda phage. The cloned apolipoprotein E genes were subcloned into a murine retrovirus shuttle vector and were expressed. One out of four clones expressed apolipoprotein E5. The analysis of the nucleotide sequence of the exons and exon-intron boundary regions has shown a G to A substitution in the 18th nucleotide from the 5'-end of the third exon. This single base substitution changes the amino acid residue Glu to Lys at the third position from the amino-terminus of the mature protein, and gives two additional units of positive charge to the molecule.     

Polymorphism of the apolipoprotein E gene and the risk of myocardial infarction

The apolipoprotein E (ApoE) gene polymorphism resulting from nucleotide substitutions in exon 4 was analyzed in Russian and Tatar patients with myocardial infarction (MI) from Bashkortostan. Alleles epsilon 2, epsilon 3, and epsilon 4 were identified by PCR. The genotype frequency distribution proved to be age-dependent in healthy Russians, genotype E2/3 increasing in frequency in subjects beyond 45. Russians who suffered MI under 45 had lower frequencies of genotype E3/3 (50.00% vs. 75.47% in controls of the same age, P = 0.013, OR = 0.33) and allele epsilon 3 (72.12% vs. 85.85%, P = 0.020, OR = 0.43) and a higher frequency of allele epsilon 4 (22.12% vs. 10.38%, P = 0.030, OR = 2.45). Russians who suffered MI complicated by cardiogenic shock (CS) had a significantly higher frequency of genotype E3/4 and lower frequencies of genotype E3/3 and allele epsilon 3 as compared with MI patients without CS. In Tatars, genotype E4/4 occurred at a frequency of 14.29% in patients who suffered MI under 45, and was not detected in healthy subjects of the same age (P = 0.024, OR = 17.85). Thus, the ApoE polymorphism was associated with higher risk of MI in Russians and Tatars under 45.