Reduced cGMP signaling associated with neointimal proliferation and vascular dysfunction in late-stage atherosclerosis

Abstract

Atherosclerosis is associated with alterations in nitric oxide (NO)/cGMP signaling. In early stages of the disease, inflammatory and possibly other cells produce reactive oxygen species that scavenge vasoprotective NO. In addition to the oxidative stress, expression and activity of enzymes downstream to NO formation may also be affected. Here, we show in the aortas of chronically hypercholesterolemic rabbits (a model of late-stage atherosclerosis), both subunits and specific activity of the NO receptor soluble guanylyl cyclase (sGC) were significantly reduced, whereas overall NO synthase activity was unaffected. These changes were most prominent in the neointimal layer, wherein cGMP-dependent protein kinase I (cGK) levels also were reduced. Additionally, a protein (p38(nt)) that was constitutively tyrosine-nitrated was detected, and its expression was significantly reduced in atherosclerotic aorta. Phosphorylation of the cGK substrate vasodilator-stimulated phosphoprotein (VASP) at Ser-239, an established biochemical endpoint of NO/cGMP signaling, also was reduced. Thus, late-stage atherosclerosis is associated not only with enhanced NO breakdown but also with altered NO reception and cGMP signaling. Preferential down-regulation in neointima suggests a direct connection of these changes to neointimal proliferation and vascular dysfunction and provides a rationale for future pharmacotherapy using classical and novel sGC activators.

Activation of Soluble Guanylate Cyclase Reverses Experimental Pulmonary Hypertension and Vascular Remodeling

“…As described previously, immunodetection of sGC␣ 1 and sGC␤ 1 subunits was performed with the use of polyclonal rabbit antibodies directed and affinity-purified against synthetic peptide sequences corresponding to human sGC␣ 1 (residues 634 to 647) and sGC␤ 1 (residues 593 to 614), respectively. 26,27 Anti-sGC␣ 1 was diluted 1:3000 and anti-sGC␤ 1 . Effects of Bay41-2272 and Bay58-2667 on the degree of muscularization of pulmonary arteries in wild-type mice.…”

Characterization of the Human α1β1 Soluble Guanylyl Cyclase Promoter

“…Exposure of cells and/or tissues to pro-inflammatory cytokines, or NO itself, also induces changes in sGC expression. For example, lipopolysaccharide (LPS), interleukin 1␤, and NO donors cause reduced sGC ␤ 1 mRNA expression in pulmonary artery smooth muscle cells (27), and in atherogenic lesions reduced sGC expression is linked to diminished cGMP-dependent signaling and neointimal proliferation (28). In contrast, augmented ␤ 1 subunit expression has been linked to increased nitrovasodilator potency in animals with endothelial dysfunction (29,30) and increased vasodilator response in aortic rings from rats after myocardial infarction (31).…”

cGMP-Dependent Protein Kinase in the Regulation of Cardiovascular Functions

“…Phosphorylation of VASP at Ser239, a specific indicator of PKG activity, was also reduced. The preferential down-regulation of cGMP/PKG signaling in neointima suggests a direct connection of these changes to neointimal proliferation and vascular dysfunction occurred in atherosclerosis (Melichar et al, 2004). It seems that the decreased PKG expression occurred only at latestage atherosclerosis, as the protein level of PKG was unaltered in Watanabe heritable hyperlipidemic rabbits of three month old (Warnholtz et al, 2002).…”