Microsoft Word - 304408R3_PAP_01_21_15

Subject codes: [162] Smooth muscle proliferation and differentiation [130] Animal models of human disease In December 2014, the average time from submission to first decision for all original research papers submitted to Circulation Research was 14.47 days. ABSTRACT Rationale: Neointimal hyperplasia characterized by abnormal accumulation of vascular smooth muscle cells (SMCs) is a hallmark of occlusive disorders such as atherosclerosis, post-angioplasty restenosis, vein graft stenosis, and allograft vasculopathy. Cyclic nucleotides are vital in SMC proliferation and migration, which are regulated by cyclic nucleotide phosphodiesterases (PDEs). Objective: Our goal is to understand the regulation and function of PDEs in SMC pathogenesis of vascular diseases. Methods and Results: We performed screening for genes differentially expressed in normal contractile versus proliferating synthetic SMCs. We observed that PDE1C expression was low in contractile SMCs but drastically elevated in synthetic SMCs in vitro and in various mouse vascular injury models in vivo. Additionally, PDE1C was highly induced in neointimal SMCs of human coronary arteries. More importantly, injury-induced neointimal formation was significantly attenuated by PDE1C deficiency or PDE1 inhibition in vivo. PDE1 inhibition suppressed vascular remodeling of human saphenous vein explants ex vivo. In cultured SMCs, PDE1C deficiency or PDE1 inhibition attenuated SMC proliferation and migration. Mechanistic studies revealed that PDE1C plays a critical role in regulating the stability of growth factor receptors, such as PDGF-receptor-beta (PDGFR known to be important in pathological vascular remodeling. PDE1C interacts with LDL-receptor-related-protein-1 (LRP1) and PDGFR, thus regulating PDGFR endocytosis and lysosome-dependent degradation in an LRP1-dependent manner. A transmembrane-adenylyl-cyclase (tmAC)-cAMP-PKA cascade modulated by PDE1C is critical in regulating PDGFR degradation. Conclusions: These findings demonstrated that PDE1C is an important regulator of SMC proliferation, migration, and neointimal hyperplasia, in part through modulating endosome/lysosome dependent PDGFR protein degradation via LRP1. Nonstandard Abbreviations and Acronyms: DES drug-eluting stent ECM extracellular matrix Epac exchange protein activated by cAMP GPCR G-protein coupled receptor FRET fluorescent resonance energy transfer G-protein coupled receptor IP immunoprecipitation LCA left carotid artery LDL low-density lipoprotein LRP1 LDL receptor-related protein 1 tmAC transmembrane adenylyl cyclase NO nitric oxide PDE cyclic nucleotide phosphodiesterase PDGFR platelet-derived growth factor receptor PGI 2 prostacyclin SMC smooth muscle cell PKA cAMP dependent protein kinase PKG cGMP-dependent protein kinase PKI PKA inhibitor RCA right carotid artery RTK receptor tyrosine kinases sGC soluble guanylate cyclase SM-MHC smooth muscle myosin heavy chain V-ATPase vacuolar-type H (+)-ATPase.