Angiotensin-Converting Enzyme Gene Polymorphism in Overweight and Obese Turkish Patients with Insulin Resistance

Beyond blood pressure, fluid and electrolyte homeostasis - Role of the renin angiotensin aldosterone system in the interplay between metabolic diseases and breast cancer

The classical renin angiotensin aldosterone system (RAAS), as well as the recently described counter-regulatory or non-canonical RAAS have been well characterized for their role in cardiovascular homeostasis. Moreover, extensive research has been conducted over the past decades on both paracrine and the endocrine roles of local RAAS in various metabolic regulations and in chronic diseases. Clinical evidence from patients on RAAS blockers as well as pre-clinical studies using rodent models of genetic manipulations of RAAS genes documented that this system may play important roles in the interplay between metabolic diseases and cancer, namely breast cancer. Some of these studies suggest potential therapeutic applications and repurposing of RAAS inhibitors for these diseases. In this review, we discuss the mechanisms by which RAAS is involved in the pathogenesis of metabolic diseases such as obesity and type-2 diabetes as well as the role of this system in the initiation, expansion and/or progression of breast cancer, especially in the context of metabolic diseases.

Association of angiotensin-converting enzyme insertion/deletion (ACE I/D) and angiotensinogen (AGT M235T) polymorphisms with the risk of obesity in a Tunisian population

Objective:

This study aims to determine whether genetic variants in ACE I/D and AGT M235T are associated with overweight-obesity and body mass index (BMI) in a Tunisian population.

Methods:

We designed an age- and sex-matched case-control study. The height and weight were measured and BMI was calculated. A total of 259 overweight-obese patients and 369 healthy controls were genotyped for the ACE I/D and AGT M235T genes using polymerase chain reaction and restriction fragment length polymorphism.

Results:

ACE I/D and AGT M235T genes were associated with BMI, waist circumference and overweight-obesity (p⩽0.001). In an additive model, the I and the M alleles in ACE and AGT variants, respectively, were associated with a lower BMI: –1.45 and −2.29 units, respectively. ACE I/D genotypes were associated with dyslipidemia; AGT M235T genotypes with dyslipidemia and total cholesterol.

Conclusion:

These data suggest that variations in ACE I/D and AGT M235T affect the risk of overweight-obesity, BMI and dyslipidemia, and could point to a key molecular pathway of metabolic syndrome and its related comorbidities.

Screening of Obese Offspring of First-Cousin Consanguineous Subjects for the Angiotensin-Converting Enzyme Gene with a 287-bp Alu Sequence

Background

Consanguinity, defined as a blood relation between couples, is associated with genetic diseases in their offspring. In Saudi Arabia, obesity is considered a major health problem associated with increased risks of cardiovascular disease, insulin resistance, and type 2 diabetes mellitus. Angiotensin-converting enzyme (ACE) with insertion (I) and deletion (D) polymorphisms of an Alu-287 bp sequence has been implicated in multiple metabolic disorders, including obesity. To date, no studies have been conducted in the Saudi population regarding the ACE gene in consanguineous offspring with obesity. Therefore, the present study aimed to investigate genetic associations in offspring of first cousins, and specifically the relationship between obesity and ACE (Alu-287 bp) was evaluated in the Saudi population.

Methods

In total, 91 cases of obesity in the offspring of first-cousin couples and 100 control subjects without obesity but with a family history of consanguinity were included. Using genomic DNA, ACE ID polymorphisms between the cases and controls were evaluated by polymerase chain reaction.

Results

There were strong differences in the height, weight, and body mass index between the cases and controls (P<0.001). A genotype analysis confirmed the strong association with allele frequencies (P<0.001; odds ratio, 4.902; 95% confidence interval, 2.867–8.379) when compared between the cases and controls. One-way analysis of variance showed a positive correlation with height and logistic regression (covariance) that could not be strongly correlated (P>0.05).

Conclusion

In conclusion, the ACE gene polymorphism was found, through allele frequencies, to be associated with obesity in the offspring of consanguineous first cousins in the Saudi population.

ACE2 and energy metabolism: the connection between COVID-19 and chronic metabolic disorders

The renin-angiotensin system (RAS) has currently attracted increasing attention due to its potential function in regulating energy homeostasis, other than the actions on cellular growth, blood pressure, fluid, and electrolyte balance. The existence of RAS is well established in metabolic organs, including pancreas, liver, skeletal muscle, and adipose tissue, where activation of angiotensin-converting enzyme (ACE) - angiotensin II pathway contributes to the impairment of insulin secretion, glucose transport, fat distribution, and adipokines production. However, the activation of angiotensin-converting enzyme 2 (ACE2) - angiotensin (1-7) pathway, a novel branch of the RAS, plays an opposite role in the ACE pathway, which could reverse these consequences by improving local microcirculation, inflammation, stress state, structure remolding, and insulin signaling pathway. In addition, new studies indicate the protective RAS arm possesses extraordinary ability to enhance brown adipose tissue (BAT) activity and induces browning of white adipose tissue, and consequently, it leads to increased energy expenditure in the form of heat instead of ATP synthesis. Interestingly, ACE2 is the receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is threating public health worldwide. The main complications of SARS-CoV-2 infected death patients include many energy metabolism-related chronic diseases, such as diabetes. The specific mechanism leading to this phenomenon is largely unknown. Here, we summarize the latest pharmacological and genetic tools on regulating ACE/ACE2 balance and highlight the beneficial effects of the ACE2 pathway axis hyperactivity on glycolipid metabolism, as well as the thermogenic modulation.

Polymorphisms of the renin-angiotensin system are not associated with overweight and obesity in a general adult population

OBJECTIVE

The increased prevalence of obesity and associated comorbidities, such as cardiovascular and metabolic diseases, has gained attention worldwide, and the renin-angiotensin system (RAS) has been pointed out as a possible link. Thus, the present study aimed to verify the possible association between angiotensinogen (AGT) or angiotensin-converting enzyme (ACE) polymorphisms with overweight and obesity in adults.

SUBJECTS AND METHODS

The present investigation was a population-based cross-sectional study including 1,567 individuals from an urban area in Brazil. Anthropometric, clinical and biochemical parameters were evaluated, and all individuals were genotyped for the ACE I/D and AGT M/T polymorphisms.

RESULTS

The prevalence of overweight was higher among men, whereas obesity was more prevalent among women. However, the frequency of ACE or AGT polymorphisms was similar among body mass index (BMI) categories. In addition, the mean age-adjusted BMI averages did not change significantly for ACE or AGT polymorphisms, regardless of sex or BMI category. The age-adjusted BMI average for the combination of ACE and AGT genotypes evidenced no significant differences regardless of sex or BMI categories. Results were similar when BMI was replaced by waist circumference (WC).

CONCLUSIONS

We were not able to find any associations between BMI and WC (overweight/obesity) and ACE and AGT polymorphisms, indicating that the RAS system might not be involved in overweight and obesity, at least based on genetic backgrounds. However, further studies must measure RAS components to elucidate this question.

Angiotensin II Signal Transduction: An Update on Mechanisms of Physiology and Pathophysiology

The renin-angiotensin-aldosterone system plays crucial roles in cardiovascular physiology and pathophysiology. However, many of the signaling mechanisms have been unclear. The angiotensin II (ANG II) type 1 receptor (AT₁R) is believed to mediate most functions of ANG II in the system. AT₁R utilizes various signal transduction cascades causing hypertension, cardiovascular remodeling, and end organ damage. Moreover, functional cross-talk between AT₁R signaling pathways and other signaling pathways have been recognized. Accumulating evidence reveals the complexity of ANG II signal transduction in pathophysiology of the vasculature, heart, kidney, and brain, as well as several pathophysiological features, including inflammation, metabolic dysfunction, and aging. In this review, we provide a comprehensive update of the ANG II receptor signaling events and their functional significances for potential translation into therapeutic strategies. AT₁R remains central to the system in mediating physiological and pathophysiological functions of ANG II, and participation of specific signaling pathways becomes much clearer. There are still certain limitations and many controversies, and several noteworthy new concepts require further support. However, it is expected that rigorous translational research of the ANG II signaling pathways including those in large animals and humans will contribute to establishing effective new therapies against various diseases.

Regulation and Functions of the Renin-Angiotensin System in White and Brown Adipose Tissue

The renin angiotensin system (RAS) is a major regulator of blood pressure, fluid, and electrolyte homeostasis. RAS precursor angiotensinogen (Agt) is cleaved into angiotensin I (Ang I) and II (Ang II) by renin and angiotensin converting enzyme (ACE), respectively. Major effects of Ang II, the main bioactive peptide of this system, is mediated by G protein coupled receptors, Angiotensin Type 1 (AGTR1, AT1R) and Type 2 (AGTR2, AT2R) receptors. Further, the discovery of additional RAS peptides such as Ang 1-7 generated by the action of another enzyme ACE2 identified novel functions of this complex system. In addition to the systemic RAS, several local RAS exist in organs such as the brain, kidney, pancreas, and adipose tissue. The expression and regulation of various components of RAS in adipose tissue prompted extensive research into the role of adipose RAS in metabolic diseases. Indeed, animal studies have shown that adipose-derived Agt contributes to circulating RAS, kidney, and blood pressure regulation. Further, mice overexpressing Agt have high blood pressure and increased adiposity characterized by inflammation, adipocyte hypertrophy, and insulin resistance, which can be reversed at least in part by RAS inhibition. These findings highlight the importance of this system in energy homeostasis, especially in the context of obesity. This overview article discusses the depot-specific functions of adipose RAS, genetic and pharmacological manipulations of RAS, and its applications to adipogenesis, thermogenesis, and overall energy homeostasis. © 2017 American Physiological Society. Compr Physiol 7:1137-1150, 2017.

The association of insertions/deletions (INDELs) and variable number tandem repeats (VNTRs) with obesity and its related traits and complications

BACKGROUND

Despite the fact that insertions/deletions (INDELs) are the second most common type of genetic variations and variable number tandem repeats (VNTRs) represent a large portion of the human genome, they have received far less attention than single nucleotide polymorphisms (SNPs) and larger forms of structural variation like copy number variations (CNVs), especially in genome-wide association studies (GWAS) of complex diseases like polygenic obesity. This is exemplified by the vast amount of review papers on the role of SNPs and CNVs in obesity, its related traits (like anthropometric measurements, biochemical variables, and eating behavior), and its related complications (like hypertension, hypertriglyceridemia, hypercholesterolemia, and insulin resistance-collectively known as metabolic syndrome). Hence, this paper reviews the types of INDELs and VNTRs that have been studied for association with obesity and its related traits and complications. These INDELs and VNTRs could be found in the obesity loci or genes from the earliest GWAS and candidate gene association studies, like FTO, genes in the leptin-proopiomelanocortin pathway, and UCP2/3. Given the important role of the brain serotonergic and dopaminergic reward system in obesity susceptibility, the association of INDELs and VNTRs in these neurotransmitters' metabolism and transport genes with obesity is also reviewed. Next, the role of INS VNTR in obesity and its related traits is questionable, since recent large-scale studies failed to replicate the earlier positive associations. As obesity results in chronic low-grade inflammation of the adipose tissue, the proinflammatory cytokine gene IL1RA and anti-inflammatory cytokine gene IL4 have VNTRs that are implicated in obesity. A systemic proinflammatory state in combination with activation of the renin-angiotensin system and decreased nitric oxide bioavailability as found in obesity leads to endothelial dysfunction. This explains why VNTR and INDEL in eNOS and ACE, respectively, could be predisposing factors of obesity. Finally, two novel genes, DOCK5 and PER3, which are involved in the regulation of the Akt/MAPK pathway and circadian rhythm, respectively, have VNTRs and INDEL that might be associated with obesity.

SHORT CONCLUSION

In conclusion, INDELs and VNTRs could have important functional consequences in the pathophysiology of obesity, and research on them should be continued to facilitate obesity prediction, prevention, and treatment.

Evaluation of Association of ADRA2A rs553668 and ACE I/D Gene Polymorphisms with Obesity Traits in the Setapak Population, Malaysia

BACKGROUND

α-adrenergic receptor 2A (ADRA2A) and angiotensin-converting enzyme (ACE) genes have been variably associated with obesity and its related phenotypes in different populations worldwide.

OBJECTIVES

This cross-sectional study aims to investigate the association of adrenergic receptor α2A (ADRA2A) rs553668 and angiotensin-converting enzyme (ACE) I/D single nucleotide polymorphisms (SNPs) with obesity traits (body mass index-BMI; waist-hip ratio-WHR; total body fat percentage - TBF) in a Malaysian population.

MATERIALS AND METHODS

Demographic and clinical variables were initially collected from 230 subjects via convenience sampling among residents and workers in Setapak, Malaysia, but in the end only 214 multi-ethnic Malaysians (99 males; 45 Malays, 116 ethnic Chinese, and 53 ethnic Indians) were available for statistical analysis. Genotyping was performed by polymerase chain reaction using DNA extracted from mouthwash samples.

RESULTS

The overall minor allele frequencies (MAFs) for ADRA2A rs553668 and ACE I/D were 0.55 and 0.56, respectively. Allele distribution of ACE I/D was significantly associated with ethnicity and WHR class. Logistic regression analysis showed that subjects with the ACE II genotype and I allele were, respectively, 2.15 and 1.55 times more likely to be centrally obese, but when adjusted for age and ethnicity, this association was abolished. Covariate analysis controlling for age, gender, and ethnicity also showed similar results, where subjects carrying the II genotype or I allele did not have significantly higher WHR. Combinatory genotype and allele analysis for ADRA2A rs553668 and ACE I/D showed that subjects with both ADRA2A rs553668 GG and ACE I/D II genotypes had significant lowest WHR compared to other genotype combinations.

CONCLUSIONS

The ACE II genotype might be a protective factor against central adiposity risk among the Malaysian population when in combination with the ADRA2A rs553668 GG genotype.

Angiotensin-converting enzyme gene insertion/deletion polymorphism with metabolic syndrome in Turkish patients

BACKGROUND

The ACE gene has received substantial attention in recent years as candidate for a variety of diseases. The most common polymorphism in ACE gene is the Insertion/Deletion (I/D, rs4646994) polymorphism located on intron 16.

AIM

We investigated the association between metabolic syndrome (MS) and the insertion (I) - deletion (D) polymorphisms in the angiotensin converting enzyme (ACE) gene in south-east of Turkey.

SUBJECTS AND METHODS

One hundred and sixty subjects, with 101 cases of MS and 59 age- and gender-matched healthy controls were included in the study.

RESULTS

The frequency of ACE I/D polymorphism was found to be 49.5% for DD, 36.6% for ID, and 13.9% for II in the MSstudy group and 44.1% for DD, 42.4% for ID and 13.5% for II in the control group. Allele frequencies were found to be 0.68% for D and 0.32% for I allele in the study group with MS and 0.65% for D, 0.35% for I allele in the control group. The I/D polymorphism of the ACE gene, DD, ID, and II genotypes occurred with similar frequencies in the study group with MS and the control group with no significant differences (p<0.05). On applying one-way analysis of variance to different ACE gene polymorphic groups in patients with MS were not significantly associated to ACE gene polymorphism and waist circumference, systolic blood pressure, diastolic blood pressure, fasting blood glucose, HDL, and LDL (p<0.05).

CONCLUSIONS

Further studies of patients in larger numbers and of different ethnic backgrounds may be necessary to elucidate the association between the ACE I/D gene polymorphism and MS.

A meta-analysis of the association between angiotensin-converting enzyme insertion/ deletion gene polymorphism and the risk of overweight/obesity

BACKGROUND AND OBJECTIVE

The association between angiotensin-converting enzyme insertion/deletion (ACE I/D) gene polymorphism and the risk of overweight/obesity remains controversial. A meta-analysis was conducted to evaluate the association between ACE I/D gene polymorphism and overweight/obesity susceptibility.

METHOD

All eligible studies were included in this meta-analysis by searching PubMed, Embase and Cochrane databases through April 2013 according to a predefined criteria.

RESULTS

Fourteen case-control studies including 3371 cases and 4490 controls were recruited for the analysis of the association between ACE I/D gene polymorphism and overweight/obesity susceptibility. A significant association was observed between DD genotype and overweight/obesity risk in overall populations and Africans (p=0.014 and 0.010, respectively). D allele was associated with the risk of overweight/ obesity in Africans (p=0.026). However, II genotype might not be a protective factor against overweight/obesity risk in overall populations, Africans, Caucasians and Asians.

CONCLUSIONS

DD genotype is a risk factor for the overweight/obesity susceptibility in overall populations, particularly in Africans. D allele is a risk factor for the overweight/obesity susceptibility in Africans. Further larger studies are needed to confirm our findings.

Association of angiotensin-converting enzyme and angiotensin II type I receptor gene polymorphisms with extreme obesity in Polish individuals

There is strong evidence for the presence of a functional renin-angiotensin system in human adipose tissue. The aim of our study was to investigate the association of polymorphic variants of angiotensin-converting enzyme gene (ACE I/D) and angiotensin II type I receptor gene (AGTR1 A1166C) with extreme obesity and obesity-associated type 2 diabetes mellitus (T2DM) and to examine their combined effect on extremely obese patients. Overall, no significant associations were detected between ACE and AGTR1 gene polymorphisms and extreme obesity. However, extremely obese patients with T2DM showed an increased frequency of ACE II genotype compared with controls (p<0.05) and with non-diabetic extremely obese patients (p<0.01). The results suggest that II genotype of ACE was a significant contributor to extreme obesity in AA homozygotes of AGTR1 gene, regardless of the presence of T2DM. Moreover, the analysis of genetic polymorphisms demonstrated that ACE II and AGTR1 AC genotypes were most frequently observed in patients with extreme obesity and T2DM. On the basis of our results, we suggest that ACE II homozygosity may be a significant predictor of extreme obesity and T2DM and that the interaction between ACE and AGTR1 genes may be considered a predisposing factor for extreme obesity and extreme obesity-associated T2DM development.

Contributions of renin-angiotensin system-related gene interactions to obesity in a Chinese population

BACKGROUND

Gene-gene interactions may be partly responsible for complex traits such as obesity. Increasing evidence suggests that the renin-angiotensin system (RAS) contributes to the etiology of obesity. How the epistasis of genes in the RAS contributes to obesity is still under research. We aim to evaluate the contribution of RAS-related gene interactions to a predisposition of obesity in a Chinese population.

METHODOLOGY AND PRINCIPAL FINDINGS

We selected six single nucleotide polymorphisms (SNPs) located in angiotensin (AGT), angiotensin converting enzyme (ACE), angiotensin type 1 receptor (AGTR1), MAS1, nitric oxide synthase 3 (NOS3) and the bradykinin B2 receptor gene (BDKRB2), and genotyped them in 324 unrelated individuals with obesity (BMI ≥ 28 kg/m(2)) and 373 non-obese controls (BMI 18.5 to <24 kg/m(2)) from a large scale population-based cohort. We analyzed gene-gene interactions among 6 polymorphic loci using the Generalized Multifactor Dimensionality Reduction (GMDR) method, which has been shown to be effective for detecting gene-gene interactions in case-control studies with relatively small samples. Then we used logistic regression models to confirm the best combination of loci identified in the GMDR. It showed a significant gene-gene interaction between the rs220721 polymorphism in the MAS1 gene and the rs1799722 polymorphism in the gene BDKB2R. The best two-locus combination scored 9 for cross-validation consistency and 9 for sign test (p = 0.0107). This interaction showed the maximum consistency and minimum prediction error among all gene-gene interaction models evaluated. Moreover, the combination of the MAS1 rs220721 and the BDKRB2 rs1799722 was associated with a significantly increased risk of obesity (OR 1.82, CI 95%: 1.15-2.88, p = 0.0103).

CONCLUSIONS AND SIGNIFICANCE

These results suggest that the SNPs from the RAS-related genes may contribute to the risk of obesity in an interactive manner in a Chinese population. The gene-gene interaction may serve as a novel area for obesity research.

Interaction of MTHFR 1298C with ACE D allele augments the risk of diabetic nephropathy in Western Iran

The aim of the current study was to examine the influence of interaction between polymorphisms of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C with angiotensin converting enzyme insertion/deletion (ACE I/D) polymorphism on the risk of diabetic nephropathy (DN). In a case control study using polymerase chain reaction (PCR)- and PCR-restriction fragment length polymorphism (RFLP), the presence of three polymorphisms in 140 patients with type 2 diabetes mellitus (T2DM) with nephropathy including patients with micro- and macro-albuminuria and 72 patients with normoalbuminuria from Western Iran were investigated. In the presence of both MTHFR 677 T and ACE D alleles, there was a trend toward increased risk of DN 2.68-fold (p=0.054). The possession of both MTHFR 677 T and ACE D alleles increased the risk of macro-albuminuria four times (p=0.035). The concomitant presence of both MTHFR 1298 C and ACE D alleles increased the risk of macro-albuminuria 7.8-fold (p=0.012). In addition, the risk of progression from micro- to macro-albuminuria in the presence of both alleles tended to be increased (4.1-fold, p=0.09). Our study for the first time demonstrated a synergistic effect between ACE I/D with either MTHFR C677T or A1298C polymorphism on the increased risk of DN among patients with T2DM. We found that MTHFR 1298 C strongly interacts with the ACE D allele and augments the risk of DN in our population.

The relationship of ACE and CETP gene polymorphisms with cardiovascular disease in a cohort of Asian Indian patients with and those without type 2 diabetes

INTRODUCTION

Hypertension and dyslipidemia have been associated with cardiovascular disease (CVD). We investigated the association of candidate gene polymorphisms in angiotensin-converting enzyme (ACE) and cholesterol ester transfer protein (CETP) genes in a cohort of Asian Indian patients with and those without type 2 diabetes.

METHODS

PCR-based genotyping of insertion/deletion (I/D) polymorphism of ACE (rs4646994) and -629C>A of CETP (rs1800775) was carried out in 520 individuals, of whom 160 had CVD+type 2 diabetes mellitus (T2DM), 90 were CVD patients without T2DM, 150 had T2DM with no cardiovascular complications, and 120 were age- and sex-matched healthy controls.

RESULTS

With respect to the ACE gene I/D polymorphism, there was a higher percentage of D/D genotype in CVD+T2DM patients, but it was not statistically significant, while the CETP -629A allele was significantly associated with CVD+T2DM patients (P=.000007; odds ratio=0.46; 95% confidence interval=0.32-0.65) as compared with the normal controls and not with CVD alone. Additive interactions between the AA+I/I genotypes, AC+I/D genotypes, and AC+D/D were identified between the patients and the controls with P values of .0052, .0009, and .0078, respectively.

CONCLUSIONS

Our study suggests that candidate gene polymorphism -629C>A of CETP may serve as a susceptibility biomarker for CVD in T2DM patients. Analyzing the combined effect of both ACE and CETP genotypes would enhance the sensitivity and specificity of CVD risk estimation in the T2DM patients in our population.