Abstract
GCN5 is a histone acetyltransferase with a role in adipogenesis. Arrhythmogenic Cardiomyopathy (ACM) is a genetic disease associated withsudden cardiac death and cardiac fibro-fatty replacement. Human primary cardiac stromal cells (CStCs ) are known to contribute to adipogenesis in the heart of ACM patients. This study aims to evaluate whether GCN5 plays a role in intracellular lipid accumulation of ACM CStCs.
CStCs are obtained from right ventricle biopsies of ACM patients and from samples of healthy cadaveric donors (CTR). Western Blot analysis reveals higher GCN5 levels in ACM CStCs compared to CTR CStCs in growth medium (ACM=1.017±0.08003, CTR=0.6187±0.09208; p<0.004). After the exposure to Adipogenic Medium (AM) for 7 days in presence of 200 µmol/L MB-3, a specific GCN5 inhibitor, ACM CStCs show a reduction of lipid accumulation (ACM AM=1236±119.6, ACM AM+MB-3=234.3±42.19; p=5.5x10-17). Intracellular lipid accumulation is also significantly decreased in ACM CStCs after GCN5 silencing by shRNA (Untrasduced=777.4±154.6, Scramble=678.4±107.4, shRNA GCN5=95.34±18.81; Untransduced vs shRNA GCN5 p=4.6x10-10; Scramble vs shRNA GCN5 p=2.04x10-23). To investigate the mechanisms involved, a transcriptomic analysis has been performed: in presence of MB-3, pathways related to metabolic processes are downregulated, while pathways related to redox balance are upregulated. In agreement, MB-3 administration is also able to reduce the mitochondrial Reactive Oxygen Species (ROS) concentration (ACM AM=4120±309.2, ACM AM+MB-3=2571±207.8; p=3.0x10-8), while the treatment of ACM CStCs with the mitochondrial ROS scavenger, MitoTempo (500 nM), significantly reduces intracellular lipid accumulation (ACM AM=1764±149.9, ACM AM+MitoTempo=1132±131.3; p=4.4x10-6). Our findings suggest that GCN5 might reduce fat accumulation of ACM CStCs, possibly by modulating intracellular redox processes.