C2238/αANP modulates apolipoprotein E through Egr-1/miR199a in vascular smooth muscle cells in vitro

Early growth response 1 exacerbates thoracic aortic aneurysm and dissection of mice by inducing the phenotypic switching of vascular smooth muscle cell through the activation of Krüppel-like factor 5

AIM

Vascular smooth muscle cell (VSMC) phenotypic switching has been reported to regulate vascular function and thoracic aortic aneurysm and dissection (TAAD) progression. Early growth response 1 (Egr1) is associated with the differentiation of VSMCs. However, the mechanisms through which Egr1 participates in the regulation of VSMCs and progression of TAAD remain unknown. This study aimed to investigate the role of Egr1 in the phenotypic switching of VSMCs and the development of TAAD.

METHODS

Wild-type C57BL/6 and SMC-specific Egr1-knockout mice were used as experimental subjects and fed β-aminopropionitrile for 4 weeks to construct the TAAD model. Ultrasound and aortic staining were performed to examine the pathological features in thoracic aortic tissues. Transwell, wound healing, CCK8, and immunofluorescence assays detected the migration and proliferation of synthetic VSMCs. Egr1 was directly bound to the promoter of Krüppel-like factor 5 (KLF5) and promoted the expression of KLF5, which was validated by JASPAR database and dual-luciferase reporter assay.

RESULTS

Egr1 expression increased and was partially co-located with VSMCs in aortic tissues of mice with TAAD. SMC-specific Egr1 deficiency alleviated TAAD and inhibited the phenotypic switching of VSMC. Egr1 knockdown prevented the phenotypic switching of VSMCs and subsequently suppressed the migration and proliferation of synthetic VSMCs. The inhibitory effects of Egr1 deficiency on VSMCs were blunted once KLF5 was overexpressed.

CONCLUSION

Egr1 aggravated the development of TAAD by promoting the phenotypic switching of VSMCs via enhancing the transcriptional activation of KLF5. These results suggest that inhibition of SMC-specific Egr1 expression is a promising therapy for TAAD.

Analysis and validation of hub genes in neutrophil extracellular traps for the long-term prognosis of myocardial infarction

INTRODUCTION

The study focuses on the long-term prognosis of myocardial infarction (MI) influenced by neutrophil extracellular traps (NETs). It also aims to analyze and validate relative hub genes in this process, in order to further explore new therapeutic targets that can improve the prognosis of MI.

MATERIALS AND METHODS

We established a MI model in mice by ligating the left anterior descending branch (LAD) and conducted an 8-week continuous observation to study the dynamic changes in the structure and function of the heart in these mice. Meanwhile, we administered Apocynin, an inhibitor of NADPH Oxidase, which has also been shown to inhibit the formation of NETs, to mice undergoing MI surgery in order to compare. This study employed hematoxylin-eosin (HE) staining, echocardiography, immunofluorescence, and real-time quantitative PCR (RT-qPCR) to examine the impact of NETs on the long-term prognosis of MI. Next, datasets related to MI and NETs were downloaded from the GEO database, respectively. The Limma package of R software was used to identify differentially expressed genes (DEGs). After analyzing the "Robust Rank Aggregation (RRA)" package, we conducted a screening for robust differentially expressed genes (DEGs) and performed pathway enrichment analysis using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) to determine the functional roles of these robust DEGs. The protein-protein interaction (PPI) network was visualized and hub genes were filtered using Cytoscape.

RESULTS

Immunofluorescence and qPCR results showed an increase in the expression of Myeloperoxidase (MPO) at week 1 and week 8 in the hearts of mice after MI. HE staining reveals a series of pathological manifestations in the heart of the MI group during 8 weeks, including enlarged size, disordered arrangement of cardiomyocytes, infiltration of inflammatory cells, and excessive deposition of collagen fibers, among others. The utilization of Apocynin could significantly improve these poor performances. The echocardiography displayed the cardiac function of the heart in mice. The MI group has a reduced range of heart movement and decreased ejection ability. Moreover, the ventricular systolic movement was found to be abnormal, and its wall thickening rate decreased over time, indicating a progressive worsening of myocardial ischemia. The Apocynin group, on the contrary, showed fewer abnormal changes in the aforementioned aspects. A total of 81 DEGs and 4 hub genes (FOS, EGR1, PTGS2, and HIST1H4H) were obtained. The results of RT-qPCR demonstrated abnormal expression of these four genes in the MI group, which could be reversed by treatment of Apocynin.

CONCLUSION

The NETs formation could be highly related to MI and the long-term prognosis of MI can be significantly influenced by the NETs formation. Four hub genes, namely FOS, EGR1, PTGS2, and HIST1H4H, have the potential to be key genes related to this process. They could also serve as biomarkers for predicting MI prognosis and as targets for gene therapy.

Atrial natriuretic peptide T2238C gene polymorphism and the risk of cardiovascular diseases: A meta‑analysis

The present study aimed to investigate the association between atrial natriuretic peptide (ANP) T2238C (rs5065) gene polymorphism and the risk of cardiovascular disease. Relevant literature was obtained by searching databases. The odds ratios (ORs) of the ANP T2238C locus genotype distribution in the case group of cardiovascular diseases and the control group of a non-cardiovascular population were pooled using R software. Sensitivity analysis was used to verify the stability of the results. Egger's linear regression test was used to assess the publication bias of the included literature. Studies were classified according to quality assessment score of the Newcastle-Ottawa scale, year, region, sample size and underlying disease for subgroup analysis, and meta-regression analysis was performed. A total of 12 studies comprising 45,619 patients were included. ANP rs5065 mutant gene C allele was a significant risk factor for myocardial infarction relative to T allele (OR=2.55, 95% CI=1.47-4.43, P=0.0008), CC+CT genotype was a significant risk factor for cerebrovascular events relative to TT (OR=1.14, 95% CI=1.04-1.26, P=0.0048) and the mutant CC genotype was a potential risk factor for the composite cardio-cerebral vascular events (CVE) relative to CT+TT (OR=1.40, 95% CI=0.96-2.04, P=0.081). In studies fulfilling the Hardy-Weinberg equilibrium, the CC genotype was a significant risk factor for the composite CVE relative to TT (OR=2.39, 95% CI=1.40-4.10, P=0.0018) and the CC genotype was a significant risk factor for composite CVE relative to CT+TT (OR=2.41, 95% CI=1.41-4.13, P=0.0015). The P-value of the Egger's test for publication bias was 0.436, which was not statistically significant. The results of the sensitivity analysis were relatively stable. Subgroup analysis indicated that the publication year was a potential source of heterogeneity. Regression analysis was performed for the recessive model in the composite CVE and the results showed that the study region (Europe) was one of the sources of heterogeneity (P=0.016). In conclusion, ANP 2238T/C mutation may increase the risk of myocardial infarction, cerebrovascular events and composite CVE.

Stroke and Etiopathogenesis: What Is Known?

Background: A substantial portion of stroke risk remains unexplained, and a contribution from genetic factors is supported by recent findings. In most cases, genetic risk factors contribute to stroke risk as part of a multifactorial predisposition. A major challenge in identifying the genetic determinants of stroke is fully understanding the complexity of the phenotype. Aims: Our narrative review is needed to improve our understanding of the biological pathways underlying the disease and, through this understanding, to accelerate the identification of new drug targets. Methods: We report, the research in the literature until February 2022 in this narrative review. The keywords are stroke, causes, etiopathogenesis, genetic, epigenetic, ischemic stroke. Results: While better risk prediction also remains a long-term goal, its implementation is still complex given the small effect-size of genetic risk variants. Some authors encourage the use of stroke genetic panels for stroke risk assessment and further stroke research. In addition, new biomarkers for the genetic causes of stroke and new targets for gene therapy are on the horizon. Conclusion: We summarize the latest evidence and perspectives of ischemic stroke genetics that may be of interest to the physician and useful for day-to-day clinical work in terms of both prevention and treatment of ischemic stroke.

Epigenetic control of natriuretic peptides: implications for health and disease

The natriuretic peptides (NPs) family, including a class of hormones and their receptors, is largely known for its beneficial effects within the cardiovascular system to preserve regular functions and health. The concentration level of each component of the family is of crucial importance to guarantee a proper control of both systemic and local cardiovascular functions. A fine equilibrium between gene expression, protein secretion and clearance is needed to achieve the final optimal level of NPs. To this aim, the regulation of gene expression and translation plays a key role. In this regard, we know the existence of fine regulatory mechanisms, the so-called epigenetic mechanisms, which target many genes at either the promoter or the 3'UTR region to inhibit or activate their expression. The gene encoding ANP (NPPA) is regulated by histone modifications, DNA methylation, distinct microRNAs and a natural antisense transcript (NPPA-AS1) with consequent implications for both health and disease conditions. Notably, ANP modulates microRNAs on its own. Histone modifications of BNP gene (NPPB) are associated with several cardiomyopathies. The proBNP processing is regulated by miR30-GALNT1/2 axis. Among other components of the NPs family, CORIN, NPRA, NPRC and NEP may undergo epigenetic regulation. A better understanding of the epigenetic control of the NPs family will allow to gain more insights on the pathological basis of common cardiovascular diseases and to identify novel therapeutic targets. The present review article aims to discuss the major achievements obtained so far with studies on the epigenetic modulation of the NPs family.

T2238C atrial natriuretic peptide gene variant and cardiovascular events in patients with atrial fibrillation: A substudy from the ATHERO-AF cohort

BACKGROUND

The T2238C variant of the atrial natriuretic peptide (ANP) gene has emerged as a novel risk factor for the incidence of cardiovascular events. However, the impact of this variant on cardiovascular outcome in patients with atrial fibrillation (AF) is unknown.

METHODS

We included 557 anticoagulated patients with non-valvular AF randomly selected from the prospective ATHERO-AF cohort. Patients underwent genetic analysis for the T2238C/ANP variant and were grouped as wild type or heterozygous or homozygous for C2238 variant allele. Primary endpoint was a composite of cardiovascular events (CVEs) including cardiovascular death, fatal/non-fatal ischemic stroke and myocardial infarction. Overall, 429 patients carried the TT wild type genotype, 110 patients (19.7%) were heterozygous (T/C) and 18 patients (3.2%) were homozygous (CC).

RESULTS

Incidence of CVEs was higher in homozygous patients for C2238 allele at unadjusted analysis (log-rank test, p = 0.042 for additive model, p = 0.043 for recessive model). The multivariable Cox proportional hazards regression analysis confirmed that C2238 ANP allele was associated with CVEs in the additive (p = 0.008) and recessive models (p = 0.005).

CONCLUSIONS

Carrier status for the C2238/ANP variant allele is associated with an increased risk of CVEs in anticoagulated AF patients.

Pathogenesis of Ischemic Stroke: Role of Epigenetic Mechanisms

Epigenetics is the branch of molecular biology that studies modifications able to change gene expression without altering the DNA sequence. Epigenetic modulations include DNA methylation, histone modifications, and noncoding RNAs. These gene modifications are heritable and modifiable and can be triggered by lifestyle and nutritional factors. In recent years, epigenetic changes have been associated with the pathogenesis of several diseases such as diabetes, obesity, renal pathology, and different types of cancer. They have also been related with the pathogenesis of cardiovascular diseases including ischemic stroke. Importantly, since epigenetic modifications are reversible processes they could assist with the development of new therapeutic approaches for the treatment of human diseases. In the present review article, we aim to collect the most recent evidence concerning the impact of epigenetic modifications on the pathogenesis of ischemic stroke in both animal models and humans.

Molecular Implications of Natriuretic Peptides in the Protection from Hypertension and Target Organ Damage Development

The pathogenesis of hypertension, as a multifactorial trait, is complex. High blood pressure levels, in turn, concur with the development of cardiovascular damage. Abnormalities of several neurohormonal mechanisms controlling blood pressure homeostasis and cardiovascular remodeling can contribute to these pathological conditions. The natriuretic peptide (NP) family (including ANP (atrial natriuretic peptide), BNP (brain natriuretic peptide), and CNP (C-type natriuretic peptide)), the NP receptors (NPRA, NPRB, and NPRC), and the related protease convertases (furin, corin, and PCSK6) constitute the NP system and represent relevant protective mechanisms toward the development of hypertension and associated conditions, such as atherosclerosis, stroke, myocardial infarction, heart failure, and renal injury. Initially, several experimental studies performed in different animal models demonstrated a key role of the NP system in the development of hypertension. Importantly, these studies provided relevant insights for a better comprehension of the pathogenesis of hypertension and related cardiovascular phenotypes in humans. Thus, investigation of the role of NPs in hypertension offers an excellent example in translational medicine. In this review article, we will summarize the most compelling evidence regarding the molecular mechanisms underlying the physiological and pathological impact of NPs on blood pressure regulation and on hypertension development. We will also discuss the protective effect of NPs toward the increased susceptibility to hypertensive target organ damage.

The T2238C Human Atrial Natriuretic Peptide Molecular Variant and the Risk of Cardiovascular Diseases

Atrial natriuretic peptide (ANP) is a cardiac hormone which plays important functions to maintain cardio-renal homeostasis. The peptide structure is highly conserved among species. However, a few gene variants are known to fall within the human ANP gene. The variant rs5065 (T2238C) exerts the most substantial effects. The T to C transition at the 2238 position of the gene (13–23% allele frequency in the general population) leads to the production of a 30-, instead of 28-, amino-acid-long α-carboxy-terminal peptide. In vitro, CC2238/αANP increases the levels of reactive oxygen species and causes endothelial damage, vascular smooth muscle cells contraction, and increased platelet aggregation. These effects are achieved through the deregulated activation of type C natriuretic peptide receptor, the consequent inhibition of adenylate cyclase activity, and the activation of Giα proteins. In vivo, endothelial dysfunction and increased platelet aggregation are present in human subjects carrying the C2238/αANP allele variant. Several studies documented an increased risk of stroke and of myocardial infarction in C2238/αANP carriers. Recently, an incomplete response to antiplatelet therapy in ischemic heart disease patients carrying the C2238/αANP variant and undergoing percutaneous coronary revascularization has been reported. In summary, the overall evidence supports the concept that T2238C/ANP is a cardiovascular genetic risk factor that needs to be taken into account in daily clinical practice.

The Light and Shadow of Senescence and Inflammation in Cardiovascular Pathology and Regenerative Medicine

Recent epidemiologic studies evidence a dramatic increase of cardiovascular diseases, especially associated with the aging of the world population. During aging, the progressive impairment of the cardiovascular functions results from the compromised tissue abilities to protect the heart against stress. At the molecular level, in fact, a gradual weakening of the cellular processes regulating cardiovascular homeostasis occurs in aging cells. Atherosclerosis and heart failure are particularly correlated with aging-related cardiovascular senescence, that is, the inability of cells to progress in the mitotic program until completion of cytokinesis. In this review, we explore the intrinsic and extrinsic causes of cellular senescence and their role in the onset of these cardiovascular pathologies. Additionally, we dissect the effects of aging on the cardiac endogenous and exogenous reservoirs of stem cells. Finally, we offer an overview on the strategies of regenerative medicine that have been advanced in the quest for heart rejuvenation.

C2238 ANP gene variant promotes increased platelet aggregation through the activation of Nox2 and the reduction of cAMP

Subjects carrying the C2238 variant of the atrial natriuretic peptide (ANP) gene have a higher occurrence of stroke and acute coronary syndrome, suggesting an increased predisposition to acute thrombotic events in these subjects. We evaluated for the first time the direct effects of mutant ANP (C2238/αANP) on platelet activation in vitro and in human subjects. In vitro, platelets were incubated with no peptide, with T2238/αANP (WT) or with C2238/αANP at different concentrations. C2238/αANP (10⁻¹⁰ M) induced higher collagen-induced platelet aggregation with respect to both control without ANP and T2238/αANP. This effect was even stronger at a higher concentration (10⁻⁶ M). Mechanistically, C2238/αANP significantly lowered platelet cAMP levels, increased ROS production and activated Nox2, with respect to both control and T2238/αANP. Forskolin, a cAMP activator, and sNOX2-tat, a Nox2 inhibitor, significantly reduced the pro-aggregant effects of C2238/αANP. In vivo, we found that platelet aggregation resulted to be higher in patients with atrial fibrillation carrying the C2238 ANP gene variant with respect to non-carriers. In conclusions, C2238/αANP promotes platelet aggregation through the activation of Nox2 and the reduction of cAMP.

Cardiac Natriuretic Peptides, Hypertension and Cardiovascular Risk

Prevalence of cardiovascular (CV) disease is increasing worldwide. One of the most important risk factors for CV disease is hypertension that is very often related to obesity and metabolic syndrome. The search for key mechanisms, linking high blood pressure (BP), glucose and lipid dysmetabolism together with higher CV risk and mortality, is attracting increasing attention. Cardiac natriuretic peptides (NPs), including ANP and BNP, may play a crucial role in maintaining CV homeostasis and cardiac health, given their impact not only on BP regulation, but also on glucose and lipid metabolism. The summa of all metabolic activities of cardiac NPs, together with their CV and sodium balance effects, may be very important in decreasing the overall CV risk. Therefore, in the next future, cardiac NPs system, with its two receptors and a neutralizing enzyme, might represent one of the main targets to treat these multiple related conditions and to reduce hypertension and metabolic-related CV risk.

Early Growth Response 1 (Egr-1) Is a Transcriptional Activator of β-Secretase 1 (BACE-1) in the Brain

Accumulation of amyloid-β peptide (Aβ) in the brain is regarded as central to Alzheimer's disease (AD) pathogenesis. Aβ is generated by a sequential cleavage of amyloid precursor protein (APP) by β-secretase 1 (BACE-1) followed by γ-secretase. BACE-1 cleavage of APP is the committed step in Aβ synthesis. Understanding the mechanism by which BACE-1 is activated leading to Aβ synthesis in the brain can provide better understanding of AD pathology and help to develop novel therapies. In this study, we found that the levels of Aβ and BACE-1 are significantly reduced in the brains of mice lacking transcription factor early growth response 1 (Egr-1) when compared with the WT. We demonstrate that in COS-7 cells, Egr-1 binds to the BACE-1 promoter and activates BACE-1 transcription. In rat hippocampal primary neurons, overexpression of Egr-1 induces BACE-1 expression, activates BACE-1, promotes amyloidogenic APP processing, and enhances Aβ synthesis. In mouse hippocampal primary neurons, knockdown of BACE-1 almost completely blocks Egr-1-induced amyloidogenic APP processing and Aβ synthesis. Our data indicate that Egr-1 promotes Aβ synthesis via transcriptional activation of BACE-1 and suggest that Egr-1 plays role in activation of BACE-1 and acceleration of Aβ synthesis in AD brain. Egr-1 is a potential therapeutic target for AD.