Estrogen receptor-beta activation results in S-nitrosylation of proteins involved in cardioprotection.
BACKGROUND
It has been shown that the activation of estrogen receptor-beta (ER-beta) plays an important cardioprotective role against ischemia/reperfusion injury. However, the mechanism for this protection is not clear. We hypothesize that estrogen protects by ER-beta activation, which leads to S-nitrosylation (SNO) of key cardioprotective proteins.


RESULTS
We treated ovariectomized C57BL/6J mice with the ER-beta selective agonist 2,2-bis(4-hydroxyphenyl)-proprionitrile (DPN), 17beta-estradiol (E2), or vehicle using Alzet minipumps for 2 weeks. Isolated hearts were Langendorff perfused and subjected to ischemia and reperfusion. Compared with vehicle-treated hearts, DPN- and E2-treated hearts had significantly better postischemic functional recovery and decreased infarct size. To test the specificity of DPN, we treated ER-beta-knockout mice with DPN. However, no cardioprotective effect of DPN was found in ER-beta-knockout mice, indicating that the DPN-induced cardioprotection occurs through the activation of ER-beta. Using DyLight-maleimide fluors and a modified biotin switch method, we used a 2-dimensional DyLight fluorescence difference gel electrophoresis proteomic method to quantify differences in SNO of proteins. DPN- and E2-treated hearts showed an increase in SNO of a number of proteins. Interestingly, many of these proteins also had been shown to have increased SNO in preconditioned hearts. In addition, the DPN-induced cardioprotection and increased SNO were abolished by treatment with a nitric oxide synthase inhibitor.


CONCLUSIONS
The activation of ER-beta by DPN treatment leads to increased protein SNO and cardioprotection against ischemia/reperfusion injury, suggesting that long-term estrogen exposure protects hearts largely via activation of ER-beta and nitric oxide/SNO signaling.
Lin
Jeffrey
J
Harvard Medical School, Boston, MA, USA.
Steenbergen
Charles
C
Murphy
Elizabeth
E
Sun
Junhui
J
D000818:Animals; D004958:Estradiol / Q000378:metabolism; D047629:Estrogen Receptor beta / Q000819:agonists / Q000378:metabolism* / Q000502:physiology; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009203:Myocardial Infarction / Q000378:metabolism* / Q000517:prevention & control*; D009569:Nitric Oxide / Q000502:physiology; D009603:Nitroso Compounds / Q000378:metabolism; D010052:Ovariectomy; D026403:S-Nitrosothiols / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology
D047629:Estrogen Receptor beta; D009603:Nitroso Compounds; D026403:S-Nitrosothiols; D009569:Nitric Oxide; D004958:Estradiol