The regulatory role of thyroid hormones in bone cell growth and differentiation.
The clinical effects of thyroid hormones on bone in hypo- and hyperthyroidism are well known but their fundamental role in the regulation of bone remodeling is still poorly understood. In this review the current literature is summarized and experimental data from our laboratory are presented. The direct stimulation of bone resorption by thyroid hormones in organ culture, which in part is mediated by prostaglandins and TGF-beta, and the effect of different agents thereon are reviewed. More recent data concerning thyroid hormone action in the osteoblastic cell line MC3T3E1, are summarized. From their effect on proliferation and alkaline phosphatase activity, we conclude that thyroid hormones accelerate osteoblastic differentiation. The regulation of the transcriptional expression of certain genes by nuclear T3 receptors and their effect on osteoblastic target genes like IGF-I are reviewed. In addition a novel role of triiodothyronine as inhibitor of growth factor induced transcriptional expression of regulatory genes (c-fos, c-jun) is suggested.
Klaushofer
K
K
Ludwig Boltzmann-Institute for Osteology, 4th Medical Department, Hanusch Hospital, Vienna, Austria.
Varga
F
F
Glantschnig
H
H
Fratzl-Zelman
N
N
Czerwenka
E
E
Leis
H J
HJ
Koller
K
K
Peterlik
M
M
D000469:Alkaline Phosphatase / Q000187:drug effects; D000818:Animals; D001842:Bone and Bones / Q000166:cytology*; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D006801:Humans; D009924:Organ Culture Techniques; D010006:Osteoblasts / Q000187:drug effects; D011453:Prostaglandins / Q000494:pharmacology; D013963:Thyroid Hormones / Q000494:pharmacology / Q000502:physiology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology
D011453:Prostaglandins; D013963:Thyroid Hormones; D016212:Transforming Growth Factor beta; D000469:Alkaline Phosphatase