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Expression of Thyroid Hormone Receptor Isoforms in Rat Growth Plate Cartilage In Vivo
Author(s) -
Ballock R. Tracy,
Mita Barry C.,
Zhou Xiaolan,
Chen Daniel H.C.,
Mink Lynn M.
Publication year - 1999
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1999.14.9.1550
Subject(s) - thyroid hormone receptor , medicine , endocrinology , thyroid , hormone , thyroid hormone receptor beta , in vivo , receptor , hormone receptor , biology , growth hormone releasing hormone receptor , cartilage , thyroid hormone receptor alpha , growth hormone receptor , gene isoform , growth hormone , gene , biochemistry , anatomy , genetics , cancer , breast cancer
Although thyroid hormone has been known for many years to be a potent regulator of skeletal maturation in vivo, it has not definitively been determined whether this effect is a result of a direct or indirect action of the hormone. Previous in vivo studies have suggested that thyroid hormone may stimulate longitudinal bone growth by increasing the secretion of growth hormone; however, growth hormone alone is unable to stimulate cartilage maturation. There are also indications that thyroid hormone is able to act directly on growth plate chondrocytes through growth hormone–independent mechanisms. In this study, we demonstrate that rat growth plate chondrocytes in vivo express genes encoding three of the four isoforms of the thyroid hormone receptors described to date, but the corresponding protein can only be detected for the TRα1 and TRβ1 isoforms of the receptor. As has been noted in other tissues, there is generally poor correlation between the mRNA levels for each isoform and the relative amount of corresponding protein as measured by immunoblotting, suggesting the possibility that receptor expression may be regulated by post‐transcriptional mechanisms.