The C2238/[alpha]ANP Variant Is a Negative Modulator of Both Viability and Function of Coronary Artery Smooth Muscle Cells

Abnormalities of vascular smooth muscle cells (VSMCs) contribute to development of vascular disease. Atrial natriuretic peptide (ANP) exerts important effects on VSMCs. A common ANP molecular variant (T2238C/[alpha]ANP) has recently emerged as a novel vascular risk factor. We aimed at identifying effects of CC2238/[alpha]ANP on viability, migration and motility in coronary artery SMCs, and the underlying signaling pathways. Cells were exposed to either TT2238/[alpha]ANP or CC2238/[alpha]ANP. At the end of treatment, cell viability, migration and motility were evaluated, along with changes in oxidative stress pathway (ROS levels, NADPH and eNOS expression), on Akt phosphorylation and miR21 expression levels. CC2238/[alpha]ANP reduced cell vitality, increased apoptosis and necrosis, increased oxidative stress levels, suppressed miR21 expression along with consistent changes of its molecular targets (PDCD4, PTEN, Bcl2) and of phosphorylated Akt levels. As a result of increased oxidative stress, CC2238/[alpha]ANP markedly stimulated cell migration and increased cell contraction. NPR-C gene silencing with specific siRNAs restored cell viability, miR21 expression, and reduced oxidative stress induced by CC2238/[alpha]ANP. The cAMP/PKA/CREB pathway, driven by NPR-C activation, significantly contributed to both miR21 and phosphoAkt reduction upon CC2238/[alpha]ANP. miR21 overexpression by mimic-hsa-miR21 rescued the cellular damage dependent on CC2238/[alpha]ANP. CC2238/[alpha]ANP negatively modulates viability through NPR-C/cAMP/PKA/CREB/miR21 signaling pathway, and it augments oxidative stress leading to increased migratory and vasoconstrictor effects in coronary artery SMCs. These novel findings further support a damaging role of this common [alpha]ANP variant on vessel wall and its potential contribution to acute coronary events.