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Ultrastructural studies of protein transport, exocytosis and iodination in thyroid follicle cells
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c5 ULTRASTRUCTURAL STUDIES OF PROTEIN TRANSPORT, EXOCYTOSIS AND IODINATION IN THYROID FOLLICLE CELLS. L.E. Ericson*, V. Johanson and T. Bfverholm, Dept. of Anatomy, University of GGteborg, S-400 33 Gothenburg, Sweden. The distribution of newly synthesized protein in rat thyroid follicles was studied by quantitative EM autoradiography l-6 h after injection of 3Hleucine. The half-life of labeled, exportable protein, determined by regression analysis, in the compartment ER-Golgi was in normal rats about 30 min and in T$-treated (2 d) rats about 60 min. The corresponding half-lives for exocytotic vesicles were about 20 and 60 min. Half-lives of exportable protein in ER-Golgi as well as in exocytotic vesicles were significantly Kinetic data decreased within 20 min after TSH given to T+-treated rats. together with stereological measurement indicated that about 80% and 40% of the apical plasma membrane was exchanged each hour in respectively normal membrane was retrieved by microand Tb-treated rats. In Tb-treatedratsthe pinocytosis and the amount of colloid removed therefore small. In normal rats, colloid was internalized mainly by colloid droplets whereas apical In colloids plasma membrane was internalized mainly by micropinocytosis. of T+-treated rats (in which protein diffusion is inhibited) newlyiodinated protein was distributed in a stable gradient in the lumen periphery. Iodine was mainly bound to "old" thyroglobulin molecules not in contact with the apical plasma membrane. TSH rapidly stimulated exocytosis and iodination. Protein iodinated during the phase of stimulated exocytosis was distributed in a different gradient suggesting that iodine now to a large extent was bound to newly synthesized protein deposited by exocytosis at the cell surface. This and previous observations indicate that TSH-stimulated exocytosis and iodination are functionally linked.
C6 ACCUMULATION OF RADIOLABELLED ANTI-THYROGLOBULIN ANTIBODY BY THYROID TISSUE OF VARIOUS THYROID DISEASES. M. Izumif H. Hirayu, S. Ohtakara, S. Yamashita, S. Morita, S. Okamoto and S. Nagataki, The First Department of Internal Medicne, Nagasaki University, Nagasaki 852 Japan This study was undertaken to investigate the accumulation of radiolabelled anti-thyroglobulin (anti-Tg) antibody by various thyroid tissues. Anti-Tg antibody was purified from serum of a patient with Hashimoto's disease using affinity column chromatography. Thyroid tissues of normal, Graves', were transplanted into nude mice one month prior to adenoma the injection of and carciyEI anti-Tg antibody. Scintigrams were taken several times until 14 days after injection. Mice were sacrificed after the last scintigram, and radioactivity in each tissue was analysed with gel filtration and affinity column chromatography using Tg, anti-Tg antibody and anti-huma that radioactivity of n12SgG antibody sepharose 4B. Scintigrams showed I was accumulated by transplanted adenoma and carcinoma tissues, but not by normal and Graves' thyroid tissues. The ratio of radioactivity of tissue to blood was approximately 2-4 in both carcinoma and adenoma tissues and about 0.5 in normal and Graves' thyroid tissues. When labelled antibody was injected to patients with thyroid carcinoma or adenoma, scintigrams showed clear accumulation of radioactivity on thyroid nodules and metastasis. These results suggest that radioimmunodetection using anti-Tg antibody is clinically useful for diagnosis of adenoma and carcinoma and that the mechanism of Tg secretion in adenoma and carcinoma is different from that in normal and Graves' thyroid.
c5 ULTRASTRUCTURAL STUDIES OF PROTEIN TRANSPORT, EXOCYTOSIS AND IODINATION IN THYROID FOLLICLE CELLS. L.E. Ericson*, V. Johanson and T. Bfverholm, Dept. of Anatomy, University of GGteborg, S-400 33 Gothenburg, Sweden. The distribution of newly synthesized protein in rat thyroid follicles was studied by quantitative EM autoradiography l-6 h after injection of 3Hleucine. The half-life of labeled, exportable protein, determined by regression analysis, in the compartment ER-Golgi was in normal rats about 30 min and in T$-treated (2 d) rats about 60 min. The corresponding half-lives for exocytotic vesicles were about 20 and 60 min. Half-lives of exportable protein in ER-Golgi as well as in exocytotic vesicles were significantly Kinetic data decreased within 20 min after TSH given to T+-treated rats. together with stereological measurement indicated that about 80% and 40% of the apical plasma membrane was exchanged each hour in respectively normal membrane was retrieved by microand Tb-treated rats. In Tb-treatedratsthe pinocytosis and the amount of colloid removed therefore small. In normal rats, colloid was internalized mainly by colloid droplets whereas apical In colloids plasma membrane was internalized mainly by micropinocytosis. of T+-treated rats (in which protein diffusion is inhibited) newlyiodinated protein was distributed in a stable gradient in the lumen periphery. Iodine was mainly bound to "old" thyroglobulin molecules not in contact with the apical plasma membrane. TSH rapidly stimulated exocytosis and iodination. Protein iodinated during the phase of stimulated exocytosis was distributed in a different gradient suggesting that iodine now to a large extent was bound to newly synthesized protein deposited by exocytosis at the cell surface. This and previous observations indicate that TSH-stimulated exocytosis and iodination are functionally linked.
C6 ACCUMULATION OF RADIOLABELLED ANTI-THYROGLOBULIN ANTIBODY BY THYROID TISSUE OF VARIOUS THYROID DISEASES. M. Izumif H. Hirayu, S. Ohtakara, S. Yamashita, S. Morita, S. Okamoto and S. Nagataki, The First Department of Internal Medicne, Nagasaki University, Nagasaki 852 Japan This study was undertaken to investigate the accumulation of radiolabelled anti-thyroglobulin (anti-Tg) antibody by various thyroid tissues. Anti-Tg antibody was purified from serum of a patient with Hashimoto's disease using affinity column chromatography. Thyroid tissues of normal, Graves', were transplanted into nude mice one month prior to adenoma the injection of and carciyEI anti-Tg antibody. Scintigrams were taken several times until 14 days after injection. Mice were sacrificed after the last scintigram, and radioactivity in each tissue was analysed with gel filtration and affinity column chromatography using Tg, anti-Tg antibody and anti-huma that radioactivity of n12SgG antibody sepharose 4B. Scintigrams showed I was accumulated by transplanted adenoma and carcinoma tissues, but not by normal and Graves' thyroid tissues. The ratio of radioactivity of tissue to blood was approximately 2-4 in both carcinoma and adenoma tissues and about 0.5 in normal and Graves' thyroid tissues. When labelled antibody was injected to patients with thyroid carcinoma or adenoma, scintigrams showed clear accumulation of radioactivity on thyroid nodules and metastasis. These results suggest that radioimmunodetection using anti-Tg antibody is clinically useful for diagnosis of adenoma and carcinoma and that the mechanism of Tg secretion in adenoma and carcinoma is different from that in normal and Graves' thyroid.