BMPR2 mutation in cardiomyocytes impairs insulin‐dependent trafficking of CD36

Abstract

In PAH, insulin resistance is associated with impaired RV function. In mouse model of PAH with mutant BMPR2, we have shown impaired fatty acid oxidation and lipid accumulation in RV cardiomyocytes. We hypothesize that in cardiomyocytes with mutant BMPR2 insulin dependent translocation of CD36, fatty acid transporter molecule, is impaired and may contribute to lipid accumulation.H9C2 cardiomyocytes were stably transfected with empty vector (control) or plasmid containing mutant BMPR2 (mutant). CD36 protein was analyzed by western and confocal microscopy at baseline (BL) and insulin stimulation (IS) at 15 minutes (m), 30m, 1 hour (h), 24h. Key intracellular insulin signaling pathway intermediates analyzed by western.At BL, CD36 was 2fold up in mutant compared to control and increased 2fold in controls at 1h of IS. In mutant, IS lead to 50% increase in CD36 from 15m to 24h. Immunolocalization studies recapitulated these findings. IS increased CD36 in the cytoplasm and plasma membrane (PM) in mutant compared to control. At BL, pAkt Ser473, a key intermediate, was 2fold up in mutant compared to control. Within 15m of IS there was 4fold increase in pAkt Ser473 in control, and droping to BL by 24h. In mutant, there was similar increase in pAkt Ser473 for 1h, before dropped to BL at 24h. In control and mutant, levels of pAkt Ser473 substrate were similar at BL. In control, IS resulted in 2 and 5fold increase in pAS160 and AS160 from 15 and 30m to 24h respectively. In mutant pAS160 increased 2fold at 15m and AS160 protein increased only slightly compared to BL.Using cardiomyocytes with mutant BMPR2, we show impaired insulin‐mediated Akt‐AS160‐CD36 trafficking resulting in enhanced CD36 translocation to PM. This altered axis may contribute to increased lipid import and cardiac lipotoxicity.1 P01 HL 108800‐01A1