Di Jeso B, Pereira R, Consiglio E, Formisano S, Satrustegui J, Sandoval I V
Centro di Endocrinologia ed Oncologia Sperimentale del CNR and Dipartimento di Biologia e Patologia Cellulare e Molecolare, Università Federico II Medical School, Napoli, Italy.
Eur J Biochem. 1998 Mar 15;252(3):583-90. doi: 10.1046/j.1432-1327.1998.2520583.x.
We have examined the effects of depleting the endoplasmic reticulum Ca2+ store on the maturation of newly synthesized thyroglobulin molecules, their export to the Golgi complex, and their secretion by FRTL-5 cells. An inhibitor of the endoplasmic reticulum Ca2+ pump, thapsigargin, and the Ca2+ ionophore A23187 depleted the endoplasmic reticulum Ca2+ store and strongly inhibited thyroglobulin secretion in cells chased in medium containing 0.1 mM Ca2+. Inhibition of thyroglobulin secretion was caused by a block in the export of newly synthesized thyroglobulin molecules from the endoplasmic reticulum to the Golgi complex, as shown by cell-fractionation experiments and the intracellular accumulation of endoH-sensitive thyroglobulin. The thyroglobulin molecules retained in the endoplasmic reticulum of cells treated with the drugs were found to assemble more slowly into dimers than thyroglobulin in control cells. Protease-sensitivity experiments demonstrated that thyroglobulin dimers assembled in the presence of thapsigargin had a different conformation with respect to dimers assembled in controls cells.
我们研究了内质网Ca2+储存耗竭对新合成的甲状腺球蛋白分子成熟、其向高尔基体复合体的转运以及FRTL-5细胞分泌的影响。内质网Ca2+泵抑制剂毒胡萝卜素和Ca2+离子载体A23187耗竭了内质网Ca2+储存，并在含0.1 mM Ca2+的培养基中追踪的细胞中强烈抑制甲状腺球蛋白分泌。细胞分级实验和内切糖苷酶H敏感的甲状腺球蛋白在细胞内的积累表明，甲状腺球蛋白分泌的抑制是由于新合成的甲状腺球蛋白分子从内质网向高尔基体复合体的转运受阻所致。与对照细胞中的甲状腺球蛋白相比，在用药物处理的细胞的内质网中保留的甲状腺球蛋白分子组装成二聚体的速度更慢。蛋白酶敏感性实验表明，在毒胡萝卜素存在下组装的甲状腺球蛋白二聚体与对照细胞中组装的二聚体具有不同的构象。
