Poster session 3

Extract

Abstract

Muscular Dystrophy (MD) is an umbrella term for genetic disorders affecting skeletal and cardiac muscle which arise due to abnormalities in the dystrophin gene. Underlying dystrophin defects cause metabolic and structural abnormalities in cardiomyocytes (CMs) which in turn become predisposed to ectopic cell death and fibro-fatty replacement. The Endogenous Cannabinoid System (ECS) is a lipid signalling network present in the cardiovascular system and comprises G-protein coupled receptors (CBR1 and CBR2), endogenous ligands (anandamide and 2-arachidonoylglycerol) and regulatory proteins (fatty acid amide hydrolase and monoacylglycerol lipase). The ECS has an emerging function in stem cell survival and differentiation, MD skeletal muscle pathology, and cardiovascular diseases in general. Induced Pluripotent Stem Cell (iPSC) technology permits the reprogramming of somatic cells (e.g. fibroblasts) into pluripotent stem cells, which can be differentiated into cells from all three germ layers including CMs. In the present study we provide evidence that the ECS is involved in somatic cell reprogramming. Specifically, the CBR1 antagonist AM251 prevented the formation of iPSC colonies (p≤0.05, vs. control conditions, Newman-Keuls multiple comparison test, n=3). CMs derived from MD patients’ iPSCs (MD-CMs) displayed disease hallmarks such as lack of dystrophin expression, increased expression of Nup153 (a cardiomyopathy-associated protein; p=0.0009, vs. healthy CMs, Student’s unpaired t test, n=3) and increased CM cell death (p≤0.0001, vs. healthy CMs, Student’s unpaired t test, n=3). Furthermore, we also provide evidence that the ECS is present in iPSCs and becomes dysregulated in MD-CMs. Our results highlight the dual functionality of the ECS in cell reprogramming and MD cardiac pathology which is of interest to cardiac disease modelling and novel drug discovery.