Wong KY, Kong TH, Poon CCW, Yu W, Zhou L, Wong MS. Icariin, a phytoestrogen, exerts rapid estrogenic actions through crosstalk of estrogen receptors in osteoblasts.
Phytother Res 2023;
37:4706-4721. [PMID:
37421324 DOI:
10.1002/ptr.7939]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 06/21/2023] [Accepted: 06/25/2023] [Indexed: 07/10/2023]
Abstract
Icariin, a flavonoid glycoside derived from Epimedium brevicornum Maxim, exerts bone protective effects via estrogen receptors (ERs). This study aimed to investigate the role of ER-α66, ER-α36, and GPER in bone metabolism in osteoblasts following treatment with icariin. Human osteoblastic MG-63 cells and osteoblast-specific ER-α66 knockout mice were employed. The ERs crosstalk in the estrogenic action of icariin was evaluated in ER-α66-negative human embryonic kidney HEK293 cells. Icariin, like E2, regulated ER-α36 and GPER protein expression in osteoblasts by downregulating them and upregulating ER-α66. ER-α36 and GPER suppressed the actions of icariin and E2 in bone metabolism. However, the in vivo administration of E2 (2 mg/kg/day) or icariin (300 mg/kg/day) restored bone conditions in KO osteoblasts. ER-α36 and GPER expression increased significantly and rapidly activated and translocated in KO osteoblasts after treatment with E2 or icariin. ER-α36 overexpression in KO osteoblasts further promoted the OPG/RANKL ratio induced by E2 or icariin treatment. This study showed icariin and E2 elicit rapid estrogenic responses in bone through recruiting ER-α66, ER-α36, and GPER. Notably, in osteoblasts lacking ER-α66, ER-α36, and GPER mediate the estrogenic effects of icariin and E2, while in intact osteoblasts, ER-α36 and GPER act as negative regulators of ER-α66.
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