Functional P2Y2 nucleotide receptors mediate uridine 5'-triphosphate-induced intimal hyperplasia in collared rabbit carotid arteries.
BACKGROUND
Extracellular uridine 5'-triphosphate (UTP) induces mitogenic activation of smooth muscle cells (SMCs) through binding to P2Y2 nucleotide receptors. P2Y2 receptor mRNA is upregulated in intimal lesions of rat aorta, but it is unclear how this G-protein-coupled receptor contributes to development of intimal hyperplasia.


RESULTS
This study used a silicone collar placed around rabbit carotid arteries to induce vascular injury and intimal thickening. Collar placement caused rapid upregulation of P2Y2 receptor mRNA in medial SMCs before appearance of neointima. Fura-2 digital imaging of single SMCs was used to measure changes in myoplasmic calcium concentration (Ca(m)) in response to P2Y receptor agonists. In contrast to UDP, activation by UTP or adenosine 5'-triphosphate (ATP) greatly increased Ca(m), which indicates upregulation of functional P2Y2 receptors at which UTP and ATP are equipotent agonists. The number of responsive cells was significantly greater for freshly dispersed SMCs from collared arteries than for controls. Perivascular infusion of UTP (100 micromol/L) within the collar significantly enhanced neointimal development. Intimas that resulted from UTP exposure were infiltrated by macrophages. Moreover, increased expression of osteopontin occurred in response to in situ application of UTP. ATP or UTP also stimulated osteopontin expression in cultured SMCs in a dose-dependent manner. Furthermore, P2Y2 antisense oligonucleotide inhibited osteopontin expression induced by UTP.


CONCLUSIONS
These findings indicate for the first time a role for the UTP/ATP receptor, P2Y2, in development of intimal hyperplasia associated with atherosclerosis and restenosis.
Seye
Cheikh I
CI
Department of Biochemistry, University of Missouri-Columbia, Columbia, Mo 65212, USA. seyec@missouri.edu
Kong
Qiongman
Q
Erb
Laurie
L
Garrad
Richard C
RC
Krugh
Brent
B
Wang
Meifang
M
Turner
John T
JT
Sturek
Michael
M
González
Fernando A
FA
Weisman
Gary A
GA
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002339:Carotid Arteries / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D016893:Carotid Stenosis / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004195:Disease Models, Animal; D004333:Drug Administration Routes; D005456:Fluorescent Dyes; D006965:Hyperplasia / Q000139:chemically induced / Q000378:metabolism* / Q000473:pathology; D015151:Immunoblotting; D007249:Inflammation / Q000139:chemically induced / Q000473:pathology; D008264:Macrophages / Q000473:pathology; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D053495:Osteopontin; D012313:RNA / Q000378:metabolism; D011817:Rabbits; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism*; D058473:Receptors, Purinergic P2Y2; D012795:Sialoglycoproteins / Q000096:biosynthesis; D017539:Tunica Intima / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D015854:Up-Regulation; D014544:Uridine Triphosphate
D005456:Fluorescent Dyes; C546387:P2ry2 protein, rat; D018048:Receptors, Purinergic P2; D058473:Receptors, Purinergic P2Y2; D012795:Sialoglycoproteins; C506897:Spp1 protein, rat; C104749:purinoceptor P2Y4; C099845:purinoceptor P2Y6; D053495:Osteopontin; D012313:RNA; D000255:Adenosine Triphosphate; D002118:Calcium; D014544:Uridine Triphosphate