Prostaglandin E2-activated Epac promotes neointimal formation of the rat ductus arteriosus by a process distinct from that of cAMP-dependent protein kinase A.
We have demonstrated that chronic stimulation of the prostaglandin E2-cAMP-dependent protein kinase A (PKA) signal pathway plays a critical role in intimal cushion formation in perinatal ductus arteriosus (DA) through promoting synthesis of hyaluronan. We hypothesized that Epac, a newly identified effector of cAMP, may play a role in intimal cushion formation (ICF) in the DA distinct from that of PKA. In the present study, we found that the levels of Epac1 and Epac2 mRNAs were significantly up-regulated in the rat DA during the perinatal period. A specific EP4 agonist, ONO-AE1-329, increased Rap1 activity in the presence of a PKA inhibitor, PKI-(14-22)-amide, in DA smooth muscle cells. 8-pCPT-2'-O-Me-cAMP (O-Me-cAMP), a cAMP analog selective to Epac activator, promoted migration of DA smooth muscle cells (SMC) in a dose-dependent manner. Adenovirus-mediated Epac1 or Epac2 gene transfer further enhanced O-Me-cAMP-induced cell migration, although the effect of Epac1 overexpression on cell migration was stronger than that of Epac2. In addition, transfection of small interfering RNAs for Epac1, but not Epac2, significantly inhibited serum-mediated migration of DA SMCs. In the presence of O-Me-cAMP, actin stress fibers were well organized with enhanced focal adhesion, and cell shape was widely expanded. Adenovirus-mediated Epac1, but not Epac2 gene transfer, induced prominent ICF in the rat DA explants when compared with those with green fluorescent protein gene transfer. The thickness of intimal cushion became significantly greater (1.98-fold) in Epac1-overexpressed DA. O-Me-cAMP did not change hyaluronan production, although it decreased proliferation of DA SMCs. The present study demonstrated that Epac, especially Epac1, plays an important role in promoting SMC migration and thereby ICF in the rat DA.
Yokoyama
Utako
U
Cardiovascular Research Institute, Yokohama City University Graduate School of Medicine, Kanagawa, Japan.
Minamisawa
Susumu
S
Quan
Hong
H
Akaike
Toru
T
Suzuki
Sayaka
S
Jin
Meihua
M
Jiao
Qibin
Q
Watanabe
Mayumi
M
Otsu
Koji
K
Iwasaki
Shiho
S
Nishimaki
Shigeru
S
Sato
Motohiko
M
Ishikawa
Yoshihiro
Y
D000256:Adenoviridae / Q000378:metabolism; D000818:Animals; D002465:Cell Movement; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004373:Ductus Arteriosus / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000378:metabolism*; D008954:Models, Biological; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction
D020662:Guanine Nucleotide Exchange Factors; C116122:RAPGEF3 protein, human; C442864:RAPGEF4 protein, human; C526973:Rapgef3 protein, rat; D017868:Cyclic AMP-Dependent Protein Kinases; D015232:Dinoprostone