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A novel interaction between thyroid hormones and 1,25(OH)(2)D(3) in osteoclast formation
Masako Miura1, Kiyoshi Tanaka, Yasato Komatsu
1Department of Medicine and Clinical Science, Graduate School of Medicine, Kyoto University, Sakyo, Kyoto, Japan.
Biochemical and Biophysical Research Communications
|February 28, 2002
Summary
Thyroid hormones, particularly T3, boost osteoclast formation by increasing RANKL. This process is amplified by vitamin D, suggesting a key interaction in bone metabolism and osteoporosis.
Area of Science:
- Endocrinology
- Bone Biology
- Molecular Biology
Background:
- Thyroid hormone excess is a significant cause of secondary osteoporosis.
- Osteoclast formation is crucial for bone remodeling and is regulated by various hormones.
Purpose of the Study:
- To investigate the role of thyroid hormones (T3 and T4) in osteoclast formation.
- To explore the interaction between thyroid hormones and 1,25(OH)(2)D(3) in regulating osteoclastogenesis.
Main Methods:
- Primary osteoblastic cells (POB) and bone marrow cells were used in co-culture systems.
- mRNA expression of RANKL and type-2 iodothyronine deiodinase (D2) was analyzed.
- The effects of T3, T4, and 1,25(OH)(2)D(3) on osteoclast formation were assessed.
Main Results:
- T3 significantly induced RANKL mRNA expression in POB cells, an effect amplified by 1,25(OH)(2)D(3).
- T3 enhanced 1,25(OH)(2)D(3)-induced osteoclast formation in co-cultures.
- T4 also enhanced 1,25(OH)(2)D(3)-induced osteoclast formation, suggesting local conversion to T3.
- 1,25(OH)(2)D(3) dose- and time-dependently induced D2 mRNA expression.
Conclusions:
- Thyroid hormones, especially T3, play a role in osteoclast formation.
- A novel interaction exists between thyroid hormones and vitamin D in regulating osteoclastogenesis.
- These findings contribute to understanding the mechanisms underlying thyroid hormone-induced osteoporosis.