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- Title
Some fine-structural findings on the thyroid gland in Apc mice that express a C-terminus lacking truncated Apc.
- Authors
Yokoyama, Atsushi; Nomura, Ryuji; Kurosumi, Masafumi; Shimomura, Atsushi; Onouchi, Takanori; Iizuka-Kogo, Akiko; Smits, Ron; Fodde, Riccardo; Itoh, Mditsuyasu; Senda, Takao
- Abstract
Adenomatous polyposis coli (Apc) is a multifunctional protein as well as a tumor suppressor. To determine the functions of the C-terminal domain of Apc, we examined Apc mice that express a truncated Apc lacking the C-terminal domain. The Apc mice were tumor free and exhibited growth retardation. We recently reported abnormalities in thyroid morphology and functions of Apc mice, although the mechanisms underlying these abnormalities are not known. In the present study, we further compared thyroid gland morphology in Apc and Apc mice. The diameters of thyroid follicles in the left and right lobes of the same thyroid gland of Apc mice were significantly different whereas the Apc mice showed no significant differences in thyroid follicle diameter between these lobes. To assess the secretory activities of thyroid follicular cells, we performed double-immunostaining of thyroglobulin, a major secretory protein of these cells, and the rough endoplasmic reticulum (rER) marker calreticulin. In the Apc follicular epithelial cells, thyroglobulin was mostly colocalized with calreticulin whereas in the Apc follicular epithelial cells, a significant amount of the cytoplasmic thyroglobulin did not colocalize with calreticulin. In addition, in thyroid-stimulating hormone (TSH)-treated Apc mice, electron microscopic analysis indicated less frequent pseudopod formation at the apical surface of the thyroid follicular cells than in Apc mice, indicating that reuptake of colloid droplets containing iodized thyroglobulin is less active. These results imply defects in intracellular thyroglobulin transport and in pseudopod formation in the follicular epithelial cells of Apc mice and suggest suppressed secretory activities of these cells.
- Subjects
THYROID gland; ADENOMATOUS polyposis coli; LABORATORY mice; TUMOR suppressor proteins; CALRETICULIN; THYROGLOBULIN; EPITHELIAL cells
- Publication
Medical Molecular Morphology, 2012, Vol 45, Issue 3, p161
- ISSN
1860-1480
- Publication type
Article
- DOI
10.1007/s00795-011-0553-4