P2Y Purinergic Receptors, Endothelial Dysfunction, and Cardiovascular Diseases

Figures

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  Figure 1. P2Y4 and P2Y12 mediate lung vascular barrier function. (A): Quantitative real-time polymerase chain reaction (qPCR) analysis of Gαi in lung microvascular endothelial cells; (B): depletion of Gαi2 attenuated ATPγS-induced increase of transendothelial electrical resistance (TER). Human lung microvascular endothelial cells (HLMVECs) were transfected with non-specific siRNA (nsRNA) or Gαi-specific siRNAs (50 nM, 72 h) and were treated with ATPγS (100 µM, arrow). Inset: Western blot analysis shows the efficiency of Gαi depletion.

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  Figure 2. P2Y-mediated mechanisms of lung endothelial barrier protection. P2Y agonists (ATP, ATPγS, or β-NAD) enhance endothelial barrier properties via consequential activation of heterotrimeric G-proteins and enzymes, like myosin light chain phosphatase (MLCP) and PKA, followed by cytoskeletal rearrangement, increased cell-cell contacts, and tightening of endothelial cell (EC) barrier, thus opposing acute lung injury progression.

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  Figure 3. P2Y1 and P2Y13 receptor expression in pulmonary artery vasa vasorum endothelial cells (VVECs). Cells were isolated from the pulmonary arteries of control and chronically hypoxic hypertensive calves. (A,B): WB analysis of P2Y1R and P2Y13R expression in VVEC-Co and VVEC-Hx. Blue arrows indicate increased expression of P2Y1R compared to P2Y13R in some VVEC-Co populations; red arrows indicate increased expression of P2Y13 compared to P2Y1R in some VVEC-Hx populations; (C): Immunofluorescent analysis of P2Y13 (red) co-expression with CD31/PECAM, CD34, and CD133 (green) in VVEC-Hx.

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  Figure 4. P2Y1, P2Y11, and P2Y13 purinergic receptors are expressed in angiogenic pulmonary artery vasa vasorum. Immunofluorescent analysis of frozen acetone/methanol-fixed tissue sections of control and chronically hypoxic rats (4 weeks, (barometric pressure) PB 430 mmHg) revealed pulmonary artery adventitial vasa vasorum expansion (white arrows) and the expression of P2Y1, P2Y11, and P2Y13 receptors (green), and α-actin (red) in chronically hypoxic, but not control animals; scale bar = 100 μm.

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  Figure 5. P2Y13 and P2Y1 receptor expression in proliferating and involuting infantile hemangiomas. (a,c,e,g): Double immunofluorescent analysis for P2Y13 and P2Y1 receptors (Alexa 594, red) and PECAM/CD31 (Alexa 488, green); nuclei were counterstained with DAPI (blue; Carl Zeiss, x40 magnification; (b,d,f,h): Immunohistochemical analysis for P2Y13 and P2Y1 receptors (AEC substrate, Olympus, X40 magnification). Tissue sections were kindly provided by Dr. Sule Cataltepe (Children’s Hospital, Boston, MA, USA).

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  Figure 6. Overview of the molecular mechanisms and endpoints on the involvement of endothelial P2Y receptors in cardiovascular disease (CVD). Pathological responses to CVD include the release of extracellular purines at the sites of injury, following by activation of P2Y receptors and specific P2YR-mediated intracellular pathways leading to either injury progression, resolution, or both in tissue- and agonist-specific manner.