Atrial Natriuretic Peptide-initiated cGMP Pathways Regulate Vasodilator-stimulated Phosphoprotein Phosphorylation and Angiogenesis in Vascular Endothelium

Abstract

cGMP is involved in numerous vascular signaling pathways, and abnormalities in these pathways have been implicated in the pathophysiology of hypertension, atherosclerosis, and diabetes (1, 2). In endothelial cells, cGMP is synthesized by two distinct guanylate cyclase (GC) 5 isoforms, the nitric oxide (NO)-activated soluble GC (sGC) and the atrial natriuretic peptide (ANP)-activated particulate GC (GC-A) (2-4). NO, produced by endothelial NO synthase (eNOS), plays a crucial role in a variety of vascular responses such as blood pressure control, platelet aggregation, and vascular smooth muscle cell proliferation (5). Activation of eNOS is strongly influenced by a diverse collection of cell surface receptors, including vascular endothelial growth factor (VEGF) receptor (KDR) and sphingosine 1-phosphate (S1P) receptor S1P 1 (Edg-1) (6, 7). ANP is released primarily by cardiac atria in response to atrial stretch; this peptide binds with high affinity to the membrane receptor guanylate cyclase GC-A located in renal cells and in the vasculature (8, 9). Activated GC-A promotes diuresis and inhibits the renin-angiotensin-aldosterone system, thereby controlling salt and water retention and blood pressure (10). Recent studies have revealed ANP to be an endogenous vasoprotective substance as well as a potent pharmacological agent in the treatment of cardiovascular diseases (10 -12). GC-A is abundantly expressed in the vascular endothelium, and binding of ANP to GC-A significantly increases intracellular cGMP levels (13-15).The principal effectors of cGMP in the cardiovascular system include cGMP-gated monovalent cation channels, phosphodiesterases, and cGMP-dependent protein kinases (PKGs) (16,17). Two mammalian PKG genes have been identified, encoding PKG I and PKG II. PKG I is the prevalent PKG isoform expressed in the cardiovascular system (17) and will be referred to here as PKG. Although the functions of PKG have been probed both with PKG knock-out mice and with analyses of cellular substrates phosphorylated by PKG, much remains to be understood about the molecular and cellular significance of PKG signaling in endothelial homeostasis. PKG knock-out mice display decreased life span, impaired vascular smooth * This work was supported in part by Grants HL46457, HL48743, GM36259 (to T. M.), HL32854, and HL70819 (to D. E. G.) from the National Institutes of Health. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C.

Factors Associated with Nitric Oxide-mediated β2 Integrin Inhibition of Neutrophils

“…To the contrary, inhibition of mGC-mediated cGMP synthesis as reported with exposures to ⅐ NO that inhibit ␤ 2 integrins could be important (18). Cytoskeletal localizations play an important role in functional consequences of protein kinases, and cGMP synthesized by mGC can activate PKG and cause VASP phosphorylation (26,43). Results in this study show that addition of 8-br-cGMP abrogates ⅐ NO-dependent ␤ 2 integrin inhibition via PKG.…”

The natriuretic peptide/guanylyl cyclase–A system functions as a stress-responsive regulator of angiogenesis in mice

“…Together with published observations in macrovascular ECs (9), these results indicate that NPs can act directly on ECs and potentiate endothelial regeneration. One possible action of endothelial GC-A/cGMP/PKG I signaling is the phosphorylation of VASP, a protein associated with focal adhesion sites and adherens junctions (37). Our experiments with primary cultured MLECs obtained from wild-type and GC-A-deficient mice as well as the experiments in RFPECs showed that BNP, via GC-A/cGMP and PKG I, leads to VASP phosphorylation in microvascular endothelia.…”

“…Our experiments with primary cultured MLECs obtained from wild-type and GC-A-deficient mice as well as the experiments in RFPECs showed that BNP, via GC-A/cGMP and PKG I, leads to VASP phosphorylation in microvascular endothelia. In macrovascular human umbilical vein ECs (HUVECs), this pathway has been shown to be important for reorganization of the actin cytoskeleton and endothelial tube formation (37). Other studies in HUVECs showed that PKG phosphorylates p21-activated kinase 1 (Pak1), thereby stimulating Pak/VASP association, which also seems to be important for endothelial migration (38).…”

IRAG and novel PKG targeting in the cardiovascular system

“…Phosphorylation of VASP at Ser239 serves as a general marker for PKG-dependent activity. In the cardiovascular system VASP is involved in the remodeling of the actin cytoskeleton and enhancement of angiogenesis (15,16). Phosphorylation of VASP by PKG at Ser239 in VSMCs reduced the binding of VASP to actin and interfered with VSMC invasion and contraction of collagen matrixes (19).…”