Pharmacological inhibition of the F₁‐ATPase/P2Y₁ pathway suppresses the effect of apolipoprotein A1 on endothelial nitric oxide synthesis and vasorelaxation

Abstract

Aim The contribution of apolipoprotein A1 (APOA1), the major apolipoprotein of high‐density lipoprotein (HDL), to endothelium‐dependent vasodilatation is unclear, and there is little information regarding endothelial receptors involved in this effect. Ecto‐F1‐ATPase is a receptor for APOA1, and its activity in endothelial cells is coupled to adenosine diphosphate (ADP)‐sensitive P2Y receptors (P2Y ADP receptors). Ecto‐F1‐ATPase is involved in APOA1–mediated cell proliferation and HDL transcytosis. Here, we investigated the effect of lipid‐free APOA1 and the involvement of ecto‐F1‐ATPase and P2Y ADP receptors on nitric oxide (NO) synthesis and the regulation of vascular tone. Method Nitric oxide synthesis was assessed in human endothelial cells from umbilical veins (HUVECs) and isolated mouse aortas. Changes in vascular tone were evaluated by isometric force measurements in isolated human umbilical and placental veins and by assessing femoral artery blood flow in conscious mice. Results Physiological concentrations of lipid‐free APOA1 enhanced endothelial NO synthesis, which was abolished by inhibitors of endothelial nitric oxide synthase (eNOS) and of the ecto‐F1‐ATPase/P2Y1 axis. Accordingly, APOA1 inhibited vasoconstriction induced by thromboxane A2 receptor agonist and increased femoral artery blood flow in mice. These effects were blunted by inhibitors of eNOS, ecto‐F1‐ATPase and P2Y1 receptor. Conclusions Using a pharmacological approach, we thus found that APOA1 promotes endothelial NO production and thereby controls vascular tone in a process that requires activation of the ecto‐F1‐ATPase/P2Y1 pathway by APOA1. Pharmacological targeting of this pathway with respect to vascular diseases should be explored.

The Endothelium Is Both a Target and a Barrier of HDL’s Protective Functions

“…In this ectopic localization, however, the enzyme acts as an ATPase and generates ADP that activates the purinerergic receptor P2Y1 [ 88 ]. The activation of ectopic beta-ATPase by apoA-I in HUVECs inhibits apoptosis, promotes cell proliferation, and induces eNOS phosphorylation by a mechanism involving P2Y1 and the serial phosphorylation of the class I PI3Kβ and Akt [ 89 , 90 , 91 ]. Inhibitors of F1-ATPase, such as inhibitory factor 1 (IF1) and oligomycin, as well as P2Y1 antagonists, completely block apoA-I-induced Akt phosphorylation as well as thromboxane-induced vasorelaxation of mouse aortas [ 89 , 91 ].…”

“…The activation of ectopic beta-ATPase by apoA-I in HUVECs inhibits apoptosis, promotes cell proliferation, and induces eNOS phosphorylation by a mechanism involving P2Y1 and the serial phosphorylation of the class I PI3Kβ and Akt [ 89 , 90 , 91 ]. Inhibitors of F1-ATPase, such as inhibitory factor 1 (IF1) and oligomycin, as well as P2Y1 antagonists, completely block apoA-I-induced Akt phosphorylation as well as thromboxane-induced vasorelaxation of mouse aortas [ 89 , 91 ]. IF1 and oligomycin also inhibit EPC proliferation, suggesting a role of the apoA-I/ecto-ATPase/P2Y1 axis in angiogenesis [ 92 ].…”

Transendothelial transport of lipoproteins

“…In hepatocytes, the released ADP activates the purinergic P2Y13 receptor to signal to an as yet unidentified mediator of low affinity HDL binding and holoparticle endocytosis [186]. In endothelial cells, apoA-I induced formation of ADP was reported to elicit signaling via P2Y1 and P2Y12 receptors [146,187]. Pharmacological Inhibition of P2Y12 interfered with the uptake and transport of HDL by BAECs [146].…”

The Interplay of Endothelial P2Y Receptors in Cardiovascular Health: From Vascular Physiology to Pathology

“…The vascular system supplies nutrients, hormones, and oxygen to organs. Its homeostasis depends on coordinated action of the blood flow [ 1 , 2 ] and its components [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ] on the vascular wall. Endothelial cells form the first line of cellular contact with blood, and they sense mechanical, metabolic, and immunological stimuli in their microenvironment through specific receptors.…”

“…P2Y 1 -R, P2Y 2 -R, and P2Y 11 -R are abundantly expressed in mature endothelial cells isolated from umbilical cord (i.e., HUVECs) [ 8 , 17 , 31 , 32 , 33 ], which are used extensively as an in vitro model to study vascular remodeling and endothelial cell function. Additional receptors have been identified in this model, including P2Y 4 -R [ 17 ], P2Y 6 -R [ 17 ], P2Y 12 -R [ 31 , 34 ], P2Y 13 -R [ 31 , 35 ], and P2Y 14 -R [ 35 ] but little is known about their functional roles in endothelial cells.…”