title: Estrogen enhances activity of Wnt signaling during osteogenesis by inducing Fhl1 expression.
abstract: Estrogen is a crucial hormone for osteoclast inhibition and for preventing osteoporosis. However, the hormone's role in osteoblast growth and differentiation remains unclear. The complexity of estrogen's role in guiding osteoblast behavior arises partly from crosstalk with other signaling pathways, including Wnt signaling. In this study, we show that the Wnt agonist, LiCl, induced Fhl1 gene expression, which substantially enhanced osteoblast differentiation. Staining with alizarin red revealed that MC3T3-E1 mineralization was enhanced by overexpression of Fhl1. In addition, Fhl1 promoted the expression of the osteogenic markers, Runt-related transcription factor 2 (Runx2), osteocalcin (OCN), and osteopontin (OPN), whereas MC3T3-E1 cells with gene knockdown of Fhl1 exhibited limited mineralization and expression of Runx2, OCN, and OPN. We further demonstrate evidences from quantitative reverse transcription real-time polymerase chain reaction and reporter assay that Fhl1 expression was synergistically stimulated by estrogen (E2) and LiCl, but reduced by the estrogen-receptor inhibitor fulvestrant (ICI 182,780). However, estrogen could not enhance osteogenesis while Fhl1 expression was knocked down. Because estrogen and Wnt signaling frequently interact in developmental processes, we propose that Fhl1 can be an acting molecule mediating both signaling pathways during osteogenesis.
authors: Department of Bio-Agricultural Sciences, National Chiayi University, Chiayi, 60004, Taiwan, ROC.
authors: Shao-Min
authors: SM
authors: Wu
authors: Department of Bio-Agricultural Sciences, National Chiayi University, Chiayi, 60004, Taiwan, ROC.
authors: Lan-Hsin
authors: LH
authors: Shih
authors: Department of Bio-Agricultural Sciences, National Chiayi University, Chiayi, 60004, Taiwan, ROC.
authors: Jing-Yu
authors: JY
authors: Lee
authors: Department of Bio-Agricultural Sciences, National Chiayi University, Chiayi, 60004, Taiwan, ROC.
authors: Yi-Jun
authors: YJ
authors: Shen
authors: Department of Bio-Agricultural Sciences, National Chiayi University, Chiayi, 60004, Taiwan, ROC.
authors: Hu-Hui
authors: HH
authors: Lee
mesh_terms: D016475:3T3 Cells; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D004357:Drug Synergism; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D065171:Estrogen Receptor Antagonists / Q000494:pharmacology; D004967:Estrogens / Q000494:pharmacology*; D000077267:Fulvestrant; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism*; D060588:LIM Domain Proteins / Q000235:genetics* / Q000378:metabolism*; D018021:Lithium Chloride / Q000494:pharmacology*; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics* / Q000378:metabolism*; D010006:Osteoblasts / Q000187:drug effects / Q000502:physiology; D010012:Osteogenesis / Q000187:drug effects*; D060449:Wnt Signaling Pathway / Q000187:drug effects*
chemical_list: D065171:Estrogen Receptor Antagonists; D004967:Estrogens; C486306:Fhl1 protein, mouse; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D009124:Muscle Proteins; D000077267:Fulvestrant; D004958:Estradiol; D018021:Lithium Chloride
keywords: DIFFERENTIATION; ESTROGEN; FHL1; OSTEOBLAST; OSTEOCALCIN; OSTEOPONTIN; RUNT-RELATED TRANSCRIPTION FACTOR 2; WNT SIGNALING