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Unliganded estrogen receptor α stimulates bone sialoprotein gene expression
Hideki Takai1, Hiroyoshi Matsumura2, Sari Matsui2
1Department of Periodontology, Nihon University School of Dentistry at Matsudo, Chiba 271-8587, Japan; Research Institute of Oral Science, Nihon University School of Dentistry at Matsudo, Chiba 271-8587, Japan.
Gene
|February 6, 2014
Summary
Estrogen receptor alpha (ERα) stimulates bone sialoprotein (BSP) gene transcription independently of estrogen. ERα targets specific DNA elements, influencing bone formation and mineralization processes.
Area of Science:
- Endocrinology
- Molecular Biology
- Skeletal Biology
Background:
- Estrogen is a critical steroid hormone for skeletal development.
- Estrogen receptors (ERα and ERβ) are transcription factors regulating gene expression.
- Bone sialoprotein (BSP) is a key protein in bone mineralization, expressed by osteoblasts.
Purpose of the Study:
- To investigate the molecular mechanisms of BSP gene regulation by estrogen and ERα.
- To determine if ERα influences BSP gene transcription in a ligand-dependent or independent manner.
Main Methods:
- Overexpression of ERα in ROS17/2.8 cells.
- Analysis of BSP mRNA levels and promoter activity using luciferase assays.
- Site-directed mutagenesis of promoter constructs (CRE and AP1/GRE elements).
- Gel shift assays to assess protein-DNA binding.
Main Results:
- ERα overexpression increased BSP mRNA levels and promoter activity.
- β-estradiol did not affect BSP mRNA or promoter activity, indicating ligand-independent ERα action.
- Mutations in CRE and AP1/GRE elements abrogated ERα-mediated BSP gene stimulation.
- ERα overexpression enhanced binding to CRE and AP1/GRE elements, confirmed by antibody studies.
Conclusions:
- ERα directly stimulates BSP gene transcription through ligand-independent binding to CRE and AP1/GRE elements in the BSP promoter.
- This mechanism highlights a novel pathway for estrogen receptor signaling in bone matrix formation.
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