Estradiol activates chloride channels via estrogen receptor-α in the cell membranes of osteoblasts

• Published in: American Journal of Physiology: Cell Physiology 2017-08, Vol.313 (2), p.C162-C172
• Main Authors: Deng, Zhiqin, Peng, Shuang, Zheng, Yanfang, Yang, Xiaoya, Zhang, Haifeng, Tan, Qiuchan, Liang, Xiechou, Gao, Hong, Li, Yuan, Huang, Yanqing, Zhu, Linyan, Jacob, Tim J C, Chen, Lixin, Wang, Liwei
• Format: Article
• Language: English
• Subjects: 17β-Estradiol; Animals; Bone growth; Bones; Cell Membrane - genetics; Cell Membrane - metabolism; Cell membranes; Cellular biology; Chloride channels; Chloride Channels - antagonists & inhibitors; Chloride Channels - biosynthesis; Chloride Channels - genetics; Chlorides; Estradiol - administration & dosage; Estrogen Receptor alpha - genetics; Estrogen Receptor alpha - metabolism; Estrogen receptors; Estrogens; Estrogens - metabolism; Fulvestrant; Immunofluorescence; Mice; Osteoblasts; Osteoblasts - metabolism; Osteogenesis; Osteogenesis - genetics; Pathology; Physiology; siRNA
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00014.2017

Estrogen plays important roles in regulation of bone formation. Cl channels in the ClC family are expressed in osteoblasts and are associated with bone physiology and pathology, but the relationship between Cl channels and estrogen is not clear. In this study the action of estrogen on Cl channels was investigated in the MC3T3-E1 osteoblast cell line. Our results show that 17β-estradiol could activate a current that reversed at a potential close to the Cl equilibrium potential, with a sequence of anion selectivity of I > Br > Cl > gluconate, and was inhibited by the Cl channel blockers 5-nitro-2-(3-phenylpropylamino)-benzoate and 4,4'-diisothiocyano-2,2'-stilbene disulfonic acid. Knockdown of ClC-3 Cl channel expression by a specific small interfering RNA to ClC-3 attenuated activation of the 17β-estradiol-induced Cl current. Extracellular application of membrane-impermeable 17β-estradiol-albumin conjugates activated a similar current. The estrogen-activated Cl current could be inhibited by the estrogen receptor (ER) antagonist fulvestrant (ICI 182780). The selective ERα agonist, but not ERβ agonist, activated a Cl current similar to that induced by 17β-estradiol. Silencing ERα expression prevented activation of estrogen-induced currents. Immunofluorescence and coimmunoprecipitation experiments demonstrated that ClC-3 Cl channels and ERα were colocalized and closely related in cells. Estrogen promoted translocation of ClC-3 and ERα to the cell membrane from the nucleus. In conclusion, our findings show that Cl channels can be activated by estrogen via ERα on the cell membrane and suggest that the ClC-3 Cl channel may be one of the targets of estrogen in the regulation of osteoblast activity.