Abstract 606: Reciprocal Gene-Gene Regulation Between GWAS Genes ADTRP and MIA3 Contributing to Susceptibility of Coronary Artery Disease

Abstract

Genome-wide association studies (GWAS) have identified >60 genomic loci for coronary artery disease (CAD), including ADTRP (regulator of TFPI and coagulation) and MIA3 (involved in ER trafficking of collagens). In this study, we hypothesized that some GWAS genes form a molecular regulatory network involved in the pathogenesis of CAD. Global microarray analysis showed that ADTRP regulated expression of MIA3 and PIK3R3 encoding the regulatory subunit 3 of PI3K. ADTRP -mediated up-regulation of PIK3R3 activates AKT, resulting in up-regulation of MIA3 . Knockdown of ADTRP expression promoted oxidized-LDL-mediated monocyte adhesion to endothelial cell (EC) and transendothelial migration of monocytes, inhibited EC proliferation and migration, and increased apoptosis, which was reversed by expression of constitutively active AKT1, while the over-expression of ADTRP in ECs blunted these processes. Knockdown of MIA3 expression also promoted monocyte adhesion to ECs and transendothelial migration of monocytes. However, knockdown of MIA3 increased ADTRP expression, suggesting that MIA3 negatively regulates ADTRP expression. Genetically, no significant interaction between ADTRP SNP rs6903956 and MIA3 SNP rs17465637 was detected in 2,185 CAD patients and 2,156 non-CAD controls by classical two-locus genotypic analysis, relative excess risk due to interaction or INTERSNP programs. We have recently found that one molecular mechanism for gene-gene interaction is positive cyclic cross-regulation of gene expression: Gene A positively regulates gene B, whereas gene B also positively regulates gene A. Here we have identified a different scenario in which gene A positively regulates gene B, but gene B negatively regulates gene A, thereby resulting in lack of gene-gene interaction. In conclusion, we have uncovered a novel molecular signaling pathway involving ADTRP and MIA3 for the pathogenesis of CAD. We show that ADTRP positively regulates PIK3R3 expression, which leads to activation of AKT and up-regulation of MIA3 , thereby regulating endothelial cell functions directly relevant to atherosclerosis. These results further support that positive cyclic cross-regulation of gene expression is a molecular mechanism for gene-gene interaction.