Isoquercitrin Promotes Angiogenesis Through the Genomic Signaling Pathway of the Estrogen Receptor-Alpha

Postmenopausal women's estrogen decline is a key factor for cardiovascular disease (CVD). Phytoestrogen may prevent CVD by protecting vascular endothelium and inhibiting vascular smooth muscle proliferation via receptor's genomic or nongenomic pathways, yet effective estrogen receptor α (ERα)-targeting phytoestrogens need further exploration. Molecular docking and thermal shift assay were used to verify compound binding to ERα. Effects of phytoestrogens on ERα nuclear translocation and transcription were evaluated in cells by high-content screening, luciferase assay, and ChIP. Tube formation assay illustrated phytoestrogen's role in angiogenesis in EAhy926 cells with different ERα forms. ERα gene or mutants were expressed in EAhy926 cell line to reveal genomic signaling. A hind-limb ischemia model of VEGFR2-Luc female mice with ovarian removal was established to demonstrate phytoestrogen's role on angiogenesis. Also, the effect of phytoestrogen on nuclear translocations of p-NF-κB, p-c-JUN, and p-p38 induced by ox-LDL or LPS in EAhy926 cells with different ERα forms was examined. Isoquercitrin (IQ) binds to ERα, promoting its nuclear translocation and transcription, and induces angiogenesis by activating ERα, enhancing VEGFR2 and VEGFA mRNA levels. Experiments show IQ activates ERα genomic signaling to promote angiogenesis, reversible by ICI 182780. IQ induces angiogenesis via ERα activation, increasing VEGFR2 and VEGFA protein expression in vivo. Also, IQ reduces nuclear translocation of p-NF-κB, p-c-JUN, and p-p38 in an ERα-dependent way and decreases their protein expression in ischemic hind-limb tissue. IQ binds to and activates ERα, promoting angiogenesis by regulating VEGF through ERα genomic signaling, showing potential for preventing and treating CVD in postmenopausal women.