PCSK9 genetic (rs11591147) and epigenetic (DNA methylation) modifications associated with PCSK9 expression and serum proteins in CAD patients

Abstract

Introduction: Proprotein convertase subtilisin/kexin type 9 (PCSK9) genetic polymorphisms play a significant role in cholesterol homeostasis. Therefore, we aimed to investigate the association of PCSK9 genetic variations NM_174936.3:c.137G>T (R46L, rs11591147) and NM_174936.3:c.1120G>T (D374Y, rs137852912), as well as promoter DNA methylation status, with mRNA expression and circulating serum protein levels in coronary artery disease (CAD) patients.Methods: The present study includes 300 CAD cases and 300 controls from South India. Biochemical assays were performed using commercially available kits. PCSK9 rs11591147 and rs137852912 polymorphisms were analyzed by the polymerase chain reaction (PCR)-restriction fragment length polymorphism method, whereas promoter DNA methylation status and gene expression were determined using methylation specific PCR and quantitative PCR respectively. Results:The genotypic distribution of PCSK9 rs11591147 revealed that individuals with the TT-genotype and T-allele have a reduced risk for CAD. Furthermore, patients with the PCSK9 rs11591147 TT genotype have a significantly lower total cholesterol and low-density lipoprotein-cholesterol levels and also higher high-density lipoproteincholesterol levels than individuals with the GG genotype. Logistic regression analysis has shown that the GG and GT (p = 1.51 Â 10 -8 , p = 1.47 Â 10 -9 ) genotypes predicted the risk for CAD with an odds ratio of 5.8 and 7.3 respectively. In addition, individuals with the TT genotype were hypermethylated at promoter DNA of PCSK9, resulting in lower mRNA expression and circulating serum proteins than in individuals with the GG genotype. In silico analyses revealed that rs11591147 T-allele has protein destabilizing capacity.

PCSK9: A Multi-Faceted Protein That Is Involved in Cardiovascular Biology

“…Additionally, nonsense mutations to PCSK9 also give protection against CAD by reducing the LDL-C levels [106]. LOF mutations are also related to an increase in the proteolysis [39,107,108] and lowering of the levels of lp(a), LDL-C and reduce the risk of cardiac complications such as MI and aortic valve stenosis [109,110]. Furthermore, LOF mutations attenuate the cytokine response in healthy as well as septic patients when they are administered LPS [60].…”

“…Furthermore, S127R and D374Y mutations increase the affinity of PCSK9 towards LDLR as well as increase the level of every apoB100-containing lipoprotein in the plasma [39,115]. Other single nucleotide polymorphisms (SNPs) increase the intima-medial thickness of the arteries [116], cause arterial plaques [117] and stimulate the progression of CVD [107]. Some variants of PCSK9 show both LOF and GOF.…”

In silico identification of single nucleotide variations at CpG sites regulating CpG island existence and size

“…DNA methylation is a common molecular alteration at CpG sites of DNA sequence which is influenced by genetic and environmental factors. DNA methylation in various cell types regulate the expression of genes and shows an association with the pathophysiology of diseases 10 – 13 .…”

“…Initially, genes under the study ACAT1 21 , 22 , APOB 23 , 24 , APOE 25 – 27 , CYBA 28 , 29 , FAS 30 , 31 , FLT1 32 , 33 , KSR2 34 , LDLR 24 , 35 , MMP9 36 , 37 , PCSK9 13 , 38 , 39 , PHOX2A 40 – 42 , REST 43 , 44 , SH2B3 45 – 47 , SORT1 48 – 50 and TIMP1 51 , 52 were selected which were found to be involved in several key regulatory pathways associated with the pathology of DM, CAD and Cancers (Supplementary Table 1 ). These genes and gene products enormously involve in various pathways: ACAT1 , PCSK9 & SORT1 in cholesterol homeostasis; APOB , APOE & LDLR in lipid metabolism; CYBA , KSR2 & PHOX2A in oxidative stress; FAS , REST & SORT1 in apoptosis; FLT1 & SH2B3 in inflammation and angiogenesis; MMP9 & TIMP1 in maintenance of extracellular matrix and vascular smooth muscle cells.…”

“…Moreover, these genes were found to have genome-wide significant loci for risk of multifactorial diseases in various populations. In addition, epigenetic studies have suggested that the DNA methylation of ACAT1 54 , APOB 55 , APOE 19 , CYBA 6 , FAS 20 , FLT1 56 , LDLR 57 , MMP9 58 , PCSK9 13 , 59 , REST 60 , SH2B3 61 , SORT1 62 and TIMP1 63 genes play a substantial role in regulation of gene expression.…”