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Testosterone increases osteoprotegerin mRNA expression in mouse osteoblast cells
1Division of Endocrinology/Metabolism, Department of Clinical Molecular Medicine, Kobe University Graduate School of Medicine, Kobe 650-0017, Japan.
Hormone and Metabolic Research = Hormon- Und Stoffwechselforschung = Hormones Et Metabolisme
|November 4, 2004
Summary
Testosterone boosts osteoprotegerin (OPG) mRNA in bone cells, potentially through the androgen receptor. This finding sheds light on how androgens regulate bone metabolism and counteract parathyroid hormone effects.
Area of Science:
- Endocrinology
- Bone Biology
- Molecular Biology
Background:
- Androgens are known to influence bone metabolism in humans and animals.
- Testosterone's inhibition of parathyroid hormone-stimulated osteoclast differentiation via the androgen receptor was previously shown.
- The precise molecular mechanisms underlying androgen action on bone cells remain incompletely understood.
Purpose of the Study:
- To investigate the effect of testosterone on the mRNA expression of osteoprotegerin (OPG) and receptor activator of nuclear factor kappa-B ligand (RANKL) in mouse bone cells and MC3T3-E1 osteoblastic cells.
- To elucidate the role of the androgen receptor in mediating testosterone's effects on OPG and RANKL expression.
- To determine if testosterone modulates the inhibitory effects of parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on OPG mRNA levels.
Main Methods:
- Semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to analyze mRNA levels.
- Primary mouse bone-cell cultures and the MC3T3-E1 osteoblastic cell line were utilized.
- Cells were treated with testosterone, 1,25-dihydroxyvitamin D3, PTH-(1-34), and alpha-dehydrotestosterone to assess their effects on OPG and RANKL mRNA expression.
Main Results:
- Testosterone significantly increased OPG mRNA expression in both mouse bone-cell cultures and MC3T3-E1 cells.
- Testosterone's induction of OPG mRNA was antagonized by PTH-(1-34) but not by 1,25(OH)2D3.
- Alpha-dehydrotestosterone, a non-aromatizable androgen, also increased OPG mRNA expression, suggesting an androgen receptor-mediated effect. Testosterone did not alter RANKL mRNA levels.
Conclusions:
- Testosterone upregulates OPG mRNA expression in mouse bone cells and osteoblastic cells, likely mediated by the androgen receptor.
- These findings suggest a mechanism by which androgens contribute to bone health by increasing OPG, a known inhibitor of osteoclastogenesis.
- Testosterone's modulation of OPG expression may play a role in counteracting the effects of PTH on bone metabolism.