Abstract 298: Flavin Containing Monooxygenase 2 in Cardiac Fibrosis

Abstract

Cardiac fibrosis is associated with clinical outcome in patients with heart failing. There is no information concerning whether flavin containing monooxygenase 2 (FMO2) is involved in the fibrotic response. Here, we demonstrate that FMO2 is consistently down-regulated after myocardial infarction (MI) in rats, non-human primates and patients with chronic MI. Furthermore, FMO2 knockdown or knockout results in significantly increased cardiac fibrosis accompanied with impaired heart function in rats. Compensation of non-myocyte FMO2 using the strategy of miR133a/1a TS aided lentivirus inhibits the cardiac fibrosis and restores the deteriorated cardiac function following MI in rats. In vitro studies showed FMO2 expression in neonatal rat cardiac fibroblasts (NRCFs) is dramatically decreased after treatment of TGF-β. FMO2 deficiency in CFs isolated from FMO2-/- rats induces augmented collagen deposition, fibroblast-myofibroblast transdifferentiation and increased phosphorylated SMAD2/3. However, overexpression of FMO2 in NRCFs or CFs from MI patients suppresses this exact process. Mechanistically, we demonstrate using mass spectrometry that FMO2 combines with cytochrome p450 superfamily 2J3 (CYP2J3) at the ubiquitination site of the latter one after TGF-β stimulation, and then blocks the CYP2J3 ubiquitination. The accumulated CYP2J3 expression induces the up-regulation and nuclear translocation of SMURF2, the E3 ubiquitin-protein ligase specifically degrades phosphorylated SMAD2/3, through a negative feedback as another substrate of SMURF2, in addition, FMO2 can competitively exploit CYP2J3 from SMURF2, thus in turn promotes nuclear translocation of SMURF2 to degrade phosphorylated SMAD2/3. Furthermore, in non-human primate MI model, delivery of non-myocyte FMO2 over-expression lentivirus significantly decreases the cardiac fibrosis and improves heart function. In summary, our study demonstrates for the first time that FMO2 is a critical determinant of cardiac fibrosis by interfering TGF-β/SMAD2/3 and provides a novel potential target for treating cardiac fibrosis.