The isoform-specific expression of the tri-iodothyronine receptor in osteoblasts and osteoclasts.

Published

Journal Article

Hyperthyroidism is associated with an increase in both osteoblast and osteoclast activity. We have previously shown that, in vitro, osteoclasts do not respond directly to tri-iodothyronine to increase bone resorption but that the effect is mediated by another bone cell, probably the osteoblast. To investigate this issue further we have studied the isoform-specific expression of thyroid receptor (TR) protein in human osteoclasts derived from an osteoclastoma (giant cell tumour of bone) and the expression of TR mRNA and protein in the osteoblastic cell lines MG 63 and UMR 106. Three major TR receptor variants have been described; TR alpha 1 and TR beta are functional receptors whereas c-erbA alpha 2 is a non-functional variant. Northern blot analysis using [32P]-cDNA probes against human TR alpha 1, c-erbA alpha 2 and TR beta demonstrated specific binding of these probes to mRNA from MG 63 and UMR 106. mRNA for all three receptor variants was observed in both cell lines, in UMR 106 multiple mRNA transcripts were present for TR alpha 1 and TR beta. Immunohistochemical staining with antibodies recognizing a common TR alpha epitope and specific c-erbA alpha 2 and TR beta epitopes extended these observations by demonstrating receptor protein in both osteoblasts and osteoclasts. These findings are consistent with previous observations of TR expression in osteoblast-like-cells and are the first direct demonstration of TR in osteoclasts.

Full Text

Duke Authors

Cited Authors

  • Allain, TJ; Yen, PM; Flanagan, AM; McGregor, AM

Published Date

  • May 1996

Published In

Volume / Issue

  • 26 / 5

Start / End Page

  • 418 - 425

PubMed ID

  • 8796370

Pubmed Central ID

  • 8796370

International Standard Serial Number (ISSN)

  • 0014-2972

Digital Object Identifier (DOI)

  • 10.1046/j.1365-2362.1996.160289.x

Language

  • eng

Conference Location

  • England