Sorting nexins (SNXs) are a large, diverse group of cytoplasmic and membrane-associated proteins that function in a variety of cellular processes, including endocytosis, protein trafficking, and the retrieval of transmembrane proteins. In this study, we demonstrated that SNX2 is expressed in columnar and active thyroid follicular cells but not in flattened inactive thyrocytes. Morphometric analysis revealed a significant correlation between SNX2 positivity and columnar cell morphology. Immunohistochemical staining of serial sections of the thyroid tissue indicated that SNX2 localization was similar to sortilin, a protein expressed by active thyrocytes. Expression of SNX2 in thyrocytes is particularly marked and extensive in most hyperstimulated thyroid disorders, including Graves disease (diffusely SNX2 positive in 73.3% patients) and functioning nodules (93.8% patients). SNX2 immunolocalization in hyperstimulated follicular epithelial cells was specific among the SNXs family members examined. These results support the utility of SNX2 as a novel marker of active thyrocytes and reflect the endosomal trafficking activity in these cells.
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*Department of Pathology, Division of Diagnostic Pathology
†Department of Pathology, Division of Pathology, Kobe University Graduate School of Medicine
‡Department of Pathology, Kuma Hospital, Kobe, Japan
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S.H. is currently receiving a grant (Grant-in-Aid for young scientists B, Kakenhi 23790399) from the Japan Society for the Promotion of Science (JSPS).
The authors declare no conflict of interest.
Reprints: Shigeo Hara, MD, PhD, Department of Pathology, Division of Diagnostic Pathology, Kobe University Graduate School of Medicine, 7-5-2 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan (e-mail: email@example.com).
Received September 8, 2012
Accepted February 5, 2013