Pin1 prolyl isomerase regulates endothelial nitric oxide synthase.
OBJECTIVE
The Pin1 prolyl isomerase acts in concert with proline-directed protein kinases to regulate function of protein substrates through isomerization of peptide bonds that link phosphoserine or phosphothreonine to proline. We sought to determine whether Pin1 interacts with endothelial nitric oxide synthase (eNOS) in endothelial cells in a manner that depends on proline-directed phosphorylation of the eNOS enzyme and whether this interaction influences basal or agonist-stimulated eNOS activity.


RESULTS
Inhibitors of the extracellular-regulated kinase (ERK) 1/2 MAP kinases inhibit proline-directed phosphorylation of eNOS at serine 116 (Ser116) in bovine aortic endothelial cells (BAECs). Moreover, eNOS and Pin1 can be coimmunoprecipitated from BAECs only when Ser116 is phosphorylated. In addition, phosphomimetic Ser116Asp eNOS, but not wild-type eNOS, can be coimmunoprecipitated with Pin1 coexpressed in COS-7 cells. Inhibition of Pin1 in BAECs by juglone or by dominant negative Pin1 increases basal and agonist-stimulated NO release from the cells, whereas overexpression of wild-type Pin1 in BAECs suppresses basal and agonist-stimulated NO production. Overexpression of wild-type Pin1 in intact aortae also reduces agonist-induced relaxation of aortic rings.


CONCLUSIONS
Our results demonstrate a novel form of eNOS regulation in endothelial cells and blood vessels through Ser116 phosphorylation-dependent interaction of eNOS with Pin1.
Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912-2500, USA.
Ling
L
Ruan
Christina M
CM
Torres
Jin
J
Qian
Feng
F
Chen
James D
JD
Mintz
David W
DW
Stepp
David
D
Fulton
Richard C
RC
Venema
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism; D019556:COS Cells; D002417:Cattle; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D023421:Models, Animal; D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D019696:Peptidylprolyl Isomerase / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D015398:Signal Transduction / Q000502:physiology; D014162:Transfection
D000072340:NIMA-Interacting Peptidylprolyl Isomerase; D052250:Nitric Oxide Synthase Type III; C000606846:PIN1 protein, human; D019696:Peptidylprolyl Isomerase