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Biomedical subjects

Takayuki Ogiwara

Publications and source records attributed to Takayuki Ogiwara.

4 recordsLinked to original sources
PubMed2005

Expression of type 2 iodothyronine deiodinase in human osteoblast is stimulated by thyrotropin.

Thyroid hormones play important roles in bone growth, development, and turnover. To exert its biological activity, T(4) needs to be converted to T(3) by iodothyronine deiodinase. In human thyroid gland as well as rat brown adipose tissue, type 2 iodothyronine deiodinase (D2) expression is regulated by a TSH receptor-cAMP-mediated mechanism. TSH receptor knockout mice demonstrated the direct effects of TSH on bone via TSH receptors found on osteoblast and osteoclast precursors. In the present study we investigated the possible expression and function of iodothyronine deiodinase and TSH receptors in human osteoblast-like osteosarcoma (SaOS-2) cells and normal human osteoblast (NHOst) cells. Iodothyronine deiodinase activity was detected in SaOS-2 cells and NHOst cells, and all of the characteristics of deiodinating activity were compatible with those of D2. Northern analysis demonstrated D2 mRNA expression in SaOS-2 cells and NHOst cells. D2 mRNA levels as well as D2 activities were rapidly increased by dibutyryl cAMP or forskolin in SaOS-2 cells and NHOst cells. TSH receptor mRNA was demonstrated in SaOS-2 cells and NHOst cells, and D2 mRNA and D2 activity were stimulated by TSH in both cells. In addition, all T(3) receptor isoforms were detected by RT-PCR in SaOS-2 cells and NHOst cells. The present results indicate the expression of functional TSH receptors and D2 in human osteoblasts and suggest previously unrecognized roles of TSH receptors and local T(3) production by D2 in the pathophysiology of human osteoblasts.

Cell Line, Tumor↗
PubMed2005

Association of antipituitary antibody and type 2 iodothyronine deiodinase antibody in patients with autoimmune thyroid disease.

Antipituitary antibody (APA) has been reported to be detected in patients with autoimmune thyroid disease. Type 2 iodothyronine deiodinase (D2) is expressed in both pituitary gland and thyroid gland. We studied the association of APA and D2 peptide antibody in patients with autoimmune thyroid disease. Rat pituitary gland homogenate and D2 peptide were used as antigens in the present study. APA and D2 peptide antibodies were measured by enzyme-linked immunosorbent assay (ELISA) in sera obtained from 42 patients with Hashimoto's disease, 26 patients with Graves' disease and 70 healthy control subjects. Moreover, D2 activity precipitation assay was performed in some patients with Hashimoto's disease. APA and D2 peptide antibody were elevated in patients with Hashimoto's disease and patients with Graves' disease, compared with control subjects. APA was positive in 32.4% (22/68), D2 peptide antibody was positive in 26.5% (18/68) of patients with autoimmune thyroid disease. APA was positive in 31.0% (13/42) of patients with Hashimoto's disease and 34.6% (9/26) of patients with Graves' disease. D2 peptide antibody was positive in 26.2% (11/42) of patients with Hashimoto's disease and 26.9% (7/26) of patients with Graves' disease. D2 peptide antibody was correlated with APA in patients with autoimmune thyroid disease. Moreover, precipitation of D2 activity was increased in some patients with Hashimoto's disease including a patient who also had idiopathic diabetes insipidus, and was correlated with D2 peptide antibody. These results suggest that D2 antibody may be associated with APA in patients with autoimmune thyroid disease.

Adolescent↗
PubMed2003

Expression of type 2 iodothyronine deiodinase in corticotropin-secreting mouse pituitary tumor cells is stimulated by glucocorticoid and corticotropin-releasing hormone.

We identified the presence of iodothyronine deiodinase in AtT-20 mouse pituitary tumor cells that secrete corticotropin. Iodothyronine deiodinating activity in AtT-20 cells fulfills all the characteristics of type 2 iodothyronine deiodinase (D2), including the inhibition by thyroid hormones, the insensitivity to inhibition by 6-propyl-2-thiouracil, and the low Michaelis-Menten constant value for T4. Northern analysis using mouse D2 cRNA probe demonstrated the hybridization signal of approximately 7.0 kb in size in AtT-20 cells. D2 activity and D2 mRNA were stimulated by glucocorticoid in a dose-dependent manner but were not stimulated by testosterone or beta-estradiol. D2 expression was stimulated by (Bu)2cAMP, and CRH in a dose-dependent manner in the presence of dexamethasone. These results suggest the previously unrecognized role of local thyroid hormone activation by D2 in the regulation of pituitary corticotrophs.

Adrenocorticotropic Hormone↗