The objective of this project is to investigate the function and underlying mechanism of the cyclic nucleotide phosphodiesterase 1C (PDE1C) in pathological vascular remodeling during atherogenesis. Cyclic AMP and cyclic GMP regulate vascular functions. PDEs by hydrolyzing cyclic nucleotides, regulate cyclic nucleotide signaling. Vascular smooth muscle cells (SMCs), upon endothelium damage, transit from contractile phenotype to synthetic phenotype. In vasculature, PDE1C expression is selectively induced in synthetic SMCs, but not in contractile SMCs or endothelial cells. Synthetic SMCs can accumulate oxidized low-density lipoprotein (oxLDL) in lysosomes, referred to as SMC-derived foam cells, that have been suggested to contribute significantly in atherosclerotic lesions. oxLDL accumulation in lysosome causes lysosome membrane permeabilization and lysosome dysfunction, which accelerates atherosclerosis progression. Our preliminary data demonstrate PDE1C deficiency significantly decreases atherosclerotic lesions in vivo. In synthetic SMCs in vitro, we found that PDE1C inhibition reduces lysosomal oxLDL accumulation and ameliorates lysosomal permeabilization. Therefore, we propose two specific aims. Aim1: Determine the roles and underlying mechanisms of PDE1C in the regulation of oxLDL accumulation and lysosomal permeabilization in synthetic SMCs in vitro. In SMCs culture, PDE1C deficiency will be examined by PDE1 activity inhibitor, PDE1C wildtype vs PDE1C knockout mouse SMCs, PDE1C shRNA, and PDE1C reconstitution by adenovirus. SMCs oxLDL accumulation and lysosomal permeabilization will be assessed by Acridine Orange staining, cathepsin B/D staining, and lysosomal galectin puncta assay. Underlying mechanistical studies will use pharmacological inhibitors, siRNA or shRNA. Aim2: Evaluate the effect of PDE1C deficiency on SMC lipid accumulation and lysosomal dysfunction in atherosclerotic lesions in vivo. We will use spontaneous atherosclerotic model induced by 4 months high fat diet in mouse for biochemical assessments in the lesion areas. We will also examine the treatment potential of PDE1 inhibition on pre-trapped lipid deposition, using an accelerated atherosclerosis mouse model induced by carotid artery partial ligation. We hypothesize that PDE1C plays an essential role in atherosclerotic vascular modeling by promoting oxLDL induced-lysosomal dysfunction in synthetic SMC. This study may have significant therapeutic impact on atherosclerosis treatment.
|Program type||Predoctoral Fellowship|
|Effective start/end date||01/01/2020 → 12/31/2021|