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Journal of Cell Science, Vol 112, Issue 8 1247-1256, Copyright © 1999 by Company of Biologists
JOURNAL ARTICLES |
D Prabakaran, RS Ahima, JW Harney, MJ Berry, PR Larsen and P Arvan
Beth Israel Hospital, Harvard Medical School, Boston, MA, USA.
Polarized trafficking signals may be interpreted differently in different cell types. In this study, we have compared the polarized trafficking of different proteins expressed endogenously in primary porcine thyroid epithelial cells to similar proteins expressed in MDCK cells. As in MDCK cells, NH4Cl treatment of filter-grown thyrocytes caused mis-sorted soluble proteins to exhibit enhanced secretion to the apical medium. In independent studies, thrombospondin 1 (a thyroid basolaterally secreted protein) was secreted basolaterally from MDCK cells. Likewise, the 5'-deiodinase (a thyroid basolateral membrane protein) encoded by the DIO1 gene was also distributed basolaterally in transfected MDCK cells. Consistent with previous reports, when the secretion of human growth hormone (an unglycosylated regulated secretory protein) was examined from transfected MDCK cells, the release was nonpolarized. However, transfected thyrocytes secreted growth hormone apically in a manner dependent upon zinc addition. Moreover, two additional regulated secretory proteins expressed in thyrocytes, thyroglobulin (the major endogenous glycoprotein) and parathyroid hormone (an unglycosylated protein expressed transiently), were secreted apically even in the absence of zinc. We hypothesize that while cellular mechanisms for interpreting polarity signals are generally similar between thyrocytes and MDCK cells, thyrocytes allow for specialized packaging of regulated secretory proteins for apical delivery, which does not require glycosylation but may involve availability of certain ions as well as appropriate intracellular compartmentation.
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  J. Kohrle, F. Jakob, B. Contempre, and J. E. Dumont Selenium, the Thyroid, and the Endocrine System Endocr. Rev., December 1, 2005; 26(7): 944 - 984. [Abstract] [Full Text] [PDF]
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 T. T. Nguyen, K. A. Mol, and J. J. DiStefano III Thyroid hormone production rates in rat liver and intestine in vivo: a novel graph theory and experimental solution Am J Physiol Endocrinol Metab, July 1, 2003; 285(1): E171 - E181. [Abstract] [Full Text] [PDF]
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 C. Curcio-Morelli, B. Gereben, A. M. Zavacki, B. W. Kim, S. Huang, J. W. Harney, P. R. Larsen, and A. C. Bianco In Vivo Dimerization of Types 1, 2, and 3 Iodothyronine Selenodeiodinases Endocrinology, March 1, 2003; 144(3): 937 - 946. [Abstract] [Full Text] [PDF]
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A. C. Bianco, D. Salvatore, B. Gereben, M. J. Berry, and P. R. Larsen Biochemistry, Cellular and Molecular Biology, and Physiological Roles of the Iodothyronine Selenodeiodinases Endocr. Rev., February 1, 2002; 23(1): 38 - 89. [Abstract] [Full Text] [PDF]
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 F. Martin-Belmonte, M. A. Alonso, X. Zhang, and P. Arvan Thyroglobulin Is Selected as Luminal Protein Cargo for Apical Transport via Detergent-resistant Membranes in Epithelial Cells J. Biol. Chem., December 22, 2000; 275(52): 41074 - 41081. [Abstract] [Full Text] [PDF]
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J. L. Leonard, T. J. Visser, and D. M. Leonard Characterization of the Subunit Structure of the Catalytically Active Type I Iodothyronine Deiodinase J. Biol. Chem., January 19, 2001; 276(4): 2600 - 2607. [Abstract] [Full Text] [PDF]
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