Evaluating the association of common APOA2 variants with type 2 diabetes

The Apo gene's genetic variants: hidden role in Asian vascular risk

Vascular risk factors, including diabetes, hypertension, hyperlipidemia, and obesity, pose significant health threats with implications extending to neuropsychiatric disorders such as stroke and Alzheimer's disease. The Asian population, in particular, appears to be disproportionately affected due to unique genetic predispositions, as well as epigenetic factors such as dietary patterns and lifestyle habits. Existing management strategies often fall short of addressing these specific needs, leading to greater challenges in prevention and treatment. This review highlights a significant gap in our understanding of the impact of genetic screening in the early detection and tailored treatment of vascular risk factors among the Asian population. Apolipoprotein, a key player in cholesterol metabolism, is primarily associated with dyslipidemia, yet emerging evidence suggests its involvement in conditions such as diabetes, hypertension, and obesity. While genetic variants of vascular risk are ethnic-dependent, current evidence indicates that epigenetics also exhibits ethnic specificity. Understanding the interplay between Apolipoprotein and genetics, particularly within diverse ethnic backgrounds, has the potential to refine risk stratification and enhance precision in management. For Caucasian carrying the APOA5 rs662799 C variant, pharmacological interventions are recommended, as dietary interventions may not be sufficient. In contrast, for Asian populations with the same genetic variant, dietary modifications are initially advised. Should dyslipidemia persist, the consideration of pharmaceutical agents such as statins is recommended.

Gene-Diet Interactions on Metabolic Disease-Related Outcomes in Southeast Asian Populations: A Systematic Review

Diabetes and obesity are chronic diseases that are a burden to low- and middle-income countries. We conducted this systematic review to understand gene-diet interactions affecting the Southeast Asian population's risk of obesity and diabetes. The literature search was performed on Google Scholar and MEDLINE (PubMed) search engines independently by four reviewers who evaluated the eligibility of articles based on inclusion criteria. Out of 19,031 articles, 20 articles examining gene-diet interactions on obesity and/or diabetes-related traits met the inclusion criteria. Three (Malaysia, Indonesia, and Singapore) out of eleven Association of Southeast Asian Nations (ASEAN) countries have conducted studies on gene-diet interactions on obesity and diabetes. From the 20 selected articles, the most common interactions were observed between macronutrients and genetic risk score (GRS) on metabolic disease-related traits in the Malay, Chinese, and Indian ethnicities. Overall, we identified 29 significant gene-diet interactions in the Southeast Asian population. The results of this systematic review demonstrate ethnic-specific gene-nutrient interactions on metabolic-disease-related traits in the Southeast Asian population. This is the first systematic review to explore gene-diet interactions on obesity and diabetes in the Southeast Asian population and further research using larger sample sizes is required for better understanding and framing nutrigenetic approaches for personalized nutrition.

Dietary acid load modifies the effects of ApoA2-265 T > C polymorphism on lipid profile and serum leptin and ghrelin levels among type 2 diabetic patients

This investigation with aimed the effect of APOA2-265 T > C polymorphism and dietary acid load (DAL) as either potential renal acid load (PRAL) and net endogenous acid production (NEAP) intake interaction on metabolic markers in type 2 diabetes mellitus (T2DM). In present cross-sectional study, 737 patients with T2DM (290 men and 447 women) were enlisted from diabetes centers in Tehran. The dietary intakes of all participants during the last year was acquired by a validated semi-quantitative food frequency (FFQ) questionnaire. Polymerase chain reaction (PCR) was used for genotyping the APOA2-265 T > C. Biochemical indises containing leptin, ghrelin, total cholesterol (Bailey et al., J Clin Invest 97:1147-1453, 1996), low-density lipoprotein cholestrol (LDL-C), high-density lipoprotein cholestrol (HDL-C), triglyceride (TG), superoxide dismutase (SOD), high sensitivy C-reactive protein (hs-CRP), total antioxidant capacity (TAC), pentraxin-3 (PTX3), prostaglandin F2α (PGF2α) and interleukin 18 (IL18) were measured by standard method. Atherogenic indices (AIP, AC, CR-I, CR-II) were calculated. The gene-diet interactions were evaluated using an GLM. The frequency overall prevalence of rs5082 genotypes was 63.82 and 36.17% for T-allele and C-allele respectively. TG, Ghrelin, and hs-CRP concentrations were significantly higher among carriers with C allele than TT homozygotes. However, TC/CC genotypes have lower PTX3 than TT homozygotes (P < 0.05). C-allele carriers had highest mean of BMI (P_NEAP=0.04, P_PRAL = 0.006), WC (P_NEAP=0.04, P_PRAL = 0.04), TC (P_NEAP=0.03, P_PRAL = 0.01), ghrelin (P_NEAP=0.01, P_PRAL = 0.04), and leptin (P_NEAP=0.04, P_PRAL = 0.03) when placed in top tertiles of NEAP and PRAL.BMI, WC, TC, ghrelin, and leptin levels may be modified in C carriers by decreasing DAL, though, further investigations are required to confirm these findings.

ApoA2-256T > C polymorphism interacts with Healthy Eating Index, Dietary Quality Index-International and Dietary Phytochemical Index to affect biochemical markers among type 2 diabetic patients

Several investigations revealed the association between ApoA2 concentration and lipid profile, inflammation and oxidative stress markers. Dietary habits also play a major role in the health status of individuals with type 2 diabetes mellitus (T2DM). This study aimed to investigate the interaction of ApoA2-256T > C with dietary indexes on ghrelin and leptin hormones together with biochemical markers among individuals with T2DM. A cross-sectional study was conducted on 726 randomly selected individuals with T2DM. A validated FFQ was used to evaluate Healthy Eating Index, Dietary Quality Index-International (DQI-I) and Dietary Phytochemical Index (DPI). ApoA2-256T > C genotypes were detected by real-time-PCR. Ghrelin, leptin and biochemical markers were also assessed. ANCOVA was used for the interaction between the polymorphism and dietary indexes. A significant interaction was observed between ApoA2-256T > C and DQI-I on high-sensitivity C-reactive protein (hs-CRP) level and superoxide dismutase (SOD) activity. Besides, the interaction of the SNP and DPI significantly affected hs-CRP and 8-isoprostane F2α (PGF2α) levels. CC in the second tertile of DPI had the lowest hs-CRP level, and it was elevated due to adhering to DQI-I (P_interaction = 0·01 and 0·04, respectively). Moreover, T-allele (protective allele) carriers with the highest level of PGF2α and SOD activity were those in the second tertile of DPI and DQI-I, respectively (P_interaction = 0·03 and 0·007, respectively). SOD activity, hs-CRP and PGF2α concentration may be modified in T-allele carriers and CC by the adherence to DPI and DQI-I, though additional studies are required to confirm these findings.

Interaction between Apo A-II -265T>C polymorphism and dietary total antioxidant capacity on some anthropometric indices and serum lipid profile in patients with type 2 diabetes mellitus

The present study aimed to investigate the interaction of Apo A-II polymorphism and dietary total antioxidant capacity (DTAC) with lipid profile and anthropometric markers in patients with type 2 diabetes (T2DM) that are at risk for atherosclerosis. This cross-sectional study was conducted on 778 patients with T2DM (35–65 years). Dietary intakes were assessed by a 147-item food frequency questionnaire. DTAC was computed using international databases. Participants were categorised into two groups based on rs5082 genotypes. The gene–diet interaction was analysed by an ANCOVA multivariate interaction model. Total cholesterol, TC; triacylglycerol, TG; high- and low-density lipoprotein, HDL and LDL; TC–HDL ratio; waist circumference, WC and body mass index, BMI were obtained according to standard protocols. Overall, the frequency of CC homozygous was 12⋅1 % among study participants. We found that a significant interaction between rs5082 variants and DTAC on mean WC (P_TEAC = 0⋅044), TC concentration (P_FRAP = 0⋅049 and P_TEAC = 0⋅031) and TC/HDL (P_FRAP = 0⋅031 and P_TRAP = 0⋅040). Among patients whose DTAC was higher than the median intake, the mean of weight, WC and TC/HDL were significantly higher only in individuals with CC genotype. Also, the high DTAC was associated with a lower TC concentration only in T-allele carriers (P_FRAP = 0⋅042). We found that adherence to a diet with high total antioxidant capacity can improve the complications of diabetes and atherosclerosis in the T carrier genotype more effectively than the CC genotype. These results could indicate the anti-atherogenic properties of Apo A-II. However, further studies are needed to shed light on this issue.

Generation of Gene-Knockout Mongolian Gerbils via CRISPR/Cas9 System

The Mongolian gerbil (Meriones unguiculatus), a well-known "multifunctional" experimental animal, plays a crucial role in the research of hearing, cerebrovascular diseases and Helicobacter pylori infection. Although the whole-genome sequencing of Mongolian gerbils has been recently completed, lack of valid gene-editing systems for gerbils largely limited the further usage of Mongolian gerbils in biomedical research. Here, efficient targeted mutagenesis in Mongolian gerbils was successfully conducted by pronuclear injection with Cas9 protein and single-guide RNAs (sgRNAs) targeting Cystatin C (Cst3) or Apolipoprotein A-II (Apoa2). We found that 22 h after human chorionic gonadotropin (hCG) injection, zygote microinjection was conducted, and the injected zygotes were transferred into the pseudopregnant gerbils, which were induced by injecting equine chorionic gonadotropin (eCG) and hCG at a 70 h interval and being caged with ligated male gerbils. We successfully obtained Cst3 and Apoa2 gene knockout gerbils with the knockout efficiencies of 55 and 30.9%, respectively. No off-target effects were detected in all knockout gerbils and the mutations can be germline-transmitted. The absence of CST3 protein was observed in the tissues of homozygous Cst3 knockout (Cst3-KO) gerbils. Interestingly, we found that disruption of the Cst3 gene led to more severe brain damage and neurological deficits after unilateral carotid artery ligation, thereby indicating that the gene modifications happened at both genetic and functional levels. In conclusion, we successfully generated a CRISPR/Cas9 system based genome editing platform for Mongolian gerbils, which provided a foundation for obtaining other genetically modified gerbil models for biomedical research.

Association between the APOA2 rs3813627 Single Nucleotide Polymorphism and HDL and APOA1 Levels Through BMI

Background: The interaction between obesity and genetic traits on high density lipoprotein (HDL) levels has been extensively studied. The variance of serum HDL has a strong genetic heritability, although the studied variant only explains a small part of this variation. The goal of this study was to investigate the associations between the apolipoprotein type 2 (APOA2) rs3813627 single nucleotide polymorphism (SNP) and anthropometric and biochemical variables, though body mass index (BMI). Methods: This study included 153 subjects (91 overweight/obese (BMI³25 kg/m²) and 62 non-obese individuals (BMI < 25 kg/m²)). The APOA2 rs3813627 SNP was selected and genotyped. Genotype analysis was performed to analyze the associations between APOA2 SNPs and anthropometric and biochemical variables through BMI. Results: The APOA2 rs3813627 TT genotype was associated with low HDL levels in comparison with the APOA2 rs3813627 GG and GT genotype in overweight/obese individuals, but not in the non-obese subjects (p < 0.05). The same trend was observed in the apolipoprotein type 1 (APOA1) protein levels (p < 0.05). Correlation analysis revealed a negative correlation between HDL and APOA1 levels and APOA2 rs3813627 SNP under recessive model (p < 0.05). The odds ratio for low HDL levels was 3.76 and 3.94 for low APOA1 levels. The mediation analysis of APOA2 rs3813627 SNP through BMI showed a full mediation on HDL and partial mediation on APOA1 levels (p < 0.05). Bioinformatic analysis showed that rs3813627 lies in the APOA2 promoter and overlaps motifs for several bound transcription factors. Conclusion: On the basis of these data, the APOA2 rs3813627 SNP is associated with low HDL and APOA1 levels susceptibility, and this effect was mediated by an increased BMI.

Identification of Sequence Variation in the Apolipoprotein A2 Gene and Their Relationship with Serum High-Density Lipoprotein Cholesterol Levels

Background:

Apolipoprotein A2 (APOA2) is the second major apolipoprotein of the high-density lipoprotein cholesterol (HDL-C). The study aim was to identify APOA2 gene variation in individuals within two extreme tails of HDL-C levels and its relationship with HDL-C level.

Methods:

This cross-sectional survey was conducted on participants from Tehran Glucose and Lipid Study (TLGS) at Research Institute for Endocrine Sciences, Tehran, Iran from April 2012 to February 2013. In total, 79 individuals with extreme low HDL-C levels (≤5^th percentile for age and gender) and 63 individuals with extreme high HDL-C levels (≥95^th percentile for age and gender) were selected. Variants were identified using DNA amplification and direct sequencing.

Results:

Screen of all exons and the core promoter region of APOA2 gene identified nine single nucleotide substitutions and one microsatellite; five of which were known and four were new variants. Of these nine variants, two were common tag single nucleotide polymorphisms (SNPs) and seven were rare SNPs. Both exonic substitutions were missense mutations and caused an amino acid change. There was a significant association between the new missense mutation (variant Chr.1:16119226, Ala98Pro) and HDL-C level.

Conclusion:

None of two common tag SNPs of rs6413453 and rs5082 contributes to the HDL-C trait in Iranian population, but a new missense mutation in APOA2 in our population has a significant association with HDL-C.

Identification of Four Mouse Diabetes Candidate Genes Altering β-Cell Proliferation

Beta-cell apoptosis and failure to induce beta-cell regeneration are hallmarks of type 2-like diabetes in mouse models. Here we show that islets from obese, diabetes-susceptible New Zealand Obese (NZO) mice, in contrast to diabetes-resistant C57BL/6J (B6)-ob/ob mice, do not proliferate in response to an in-vivo glucose challenge but lose their beta-cells. Genome-wide RNAseq based transcriptomics indicated an induction of 22 cell cycle-associated genes in B6-ob/ob islets that did not respond in NZO islets. Of all genes differentially expressed in islets of the two strains, seven mapped to the diabesity QTL Nob3, and were hypomorphic in either NZO (Lefty1, Apoa2, Pcp4l1, Mndal, Slamf7, Pydc3) or B6 (Ifi202b). Adenoviral overexpression of Lefty1, Apoa2, and Pcp4l1 in primary islet cells increased proliferation, whereas overexpression of Ifi202b suppressed it. We conclude that the identified genes in synergy with obesity and insulin resistance participate in adaptive islet hyperplasia and prevention from severe diabetes in B6-ob/ob mice.

Complex genetic determinants contribute to an inherent susceptibility of type 2 diabetes, characterized by insulin resistance, a dysfunction and loss of insulin-producing beta-cells. We compared the islet expression profile and the genome of two obese mouse strains that react differently when receiving a caloric enriched diet. One mouse (B6-ob/ob) is able to compensate by increasing the beta-cell mass, whereas the other (NZO) develops hyperglycemia due to beta-cells loss. Focusing on differentially expressed genes that are located in susceptibility locus for diabetes and obesity on chromosome 1 we found 6 genes to be only expressed in islets of the diabetes-resistant mouse and one to be exclusively present in islets of the diabetes-prone mouse. Among these, the overexpression of 3 genes (Lefty1, Apoa2, and Pcp4l1) increased and that of Ifi202b decreased the division of primary islet cells. In summary, our data provide new insights into genes inducing or inhibiting islet size and thereby participate in the pathogenesis of type 2 diabetes.

Studies of gene variants related to inflammation, oxidative stress, dyslipidemia, and obesity: implications for a nutrigenetic approach

Obesity is currently considered a serious public health issue due to its strong impact on health, economy, and quality of life. It is considered a chronic low-grade inflammation state and is directly involved in the genesis of metabolic disturbances, such as insulin resistance and dyslipidemia, which are well-known risk factors for cardiovascular disease. Furthermore, there is evidence that genetic variation that predisposes to inflammation and metabolic disturbances could interact with environmental factors, such as diet, modulating individual susceptibility to developing these conditions. This paper aims to review the possible interactions between diet and single-nucleotide polymorphisms (SNPs) in genes implicated on the inflammatory response, lipoprotein metabolism, and oxidative status. Therefore, the impact of genetic variants of the peroxisome proliferator-activated receptor-(PPAR-)gamma, tumor necrosis factor-(TNF-)alpha, interleukin (IL)-1, IL-6, apolipoprotein (Apo) A1, Apo A2, Apo A5, Apo E, glutathione peroxidases 1, 2, and 4, and selenoprotein P exposed to variations on diet composition is described.

Association between the APOA2 promoter polymorphism and body weight in Mediterranean and Asian populations: replication of a gene-saturated fat interaction

OBJECTIVE

The APOA2 gene has been associated with obesity and insulin resistance (IR) in animal and human studies with controversial results. We have reported an APOA2-saturated fat interaction determining body mass index (BMI) and obesity in American populations. This work aims to extend our findings to European and Asian populations.

METHODS

Cross-sectional study in 4602 subjects from two independent populations: a high-cardiovascular risk Mediterranean population (n = 907 men and women; aged 67 ± 6 years) and a multiethnic Asian population (n = 2506 Chinese, n = 605 Malays and n = 494 Asian Indians; aged 39 ± 12 years) participating in a Singapore National Health Survey. Anthropometric, clinical, biochemical, lifestyle and dietary variables were determined. Homeostasis model assessment of insulin resistance was used in Asians. We analyzed gene-diet interactions between the APOA2 -265T>C polymorphism and saturated fat intake (<or ≥ 22 g per day) on anthropometric measures and IR.

RESULTS

Frequency of CC (homozygous for the minor allele) subjects differed among populations (1-15%). We confirmed a recessive effect of the APOA2 polymorphism and replicated the APOA2-saturated fat interaction on body weight. In Mediterranean individuals, the CC genotype was associated with a 6.8% greater BMI in those consuming a high (P = 0.018), but not a low (P = 0.316) saturated fat diet. Likewise, the CC genotype was significantly associated with higher obesity prevalence in Chinese and Asian Indians only, with a high-saturated fat intake (P = 0.036). We also found a significant APOA2-saturated fat interaction in determining IR in Chinese and Asian Indians (P = 0.026).

CONCLUSION

The influence of the APOA2 -265T>C polymorphism on body-weight-related measures was modulated by saturated fat in Mediterranean and Asian populations.