Desruisseau S, Valette A, Franc J L, Chabaud O
INSERM CJF 93-11, Faculté de Médecine Nord, Marseille, France.
Mol Cell Endocrinol. 1996 Sep 18;122(2):223-8. doi: 10.1016/0303-7207(96)03880-4.
We previously showed that thyroglobulin (Tg) glycosylation is enhanced 1.5-fold under thyrotropin (TSH) stimulation, corresponding to an increased number of oligosaccharide chains per molecule of Tg. Now the steps involving dolichol components and oligosaccharyltransferase activity have been studied. Porcine thyroid cells were cultured on porous bottom filters with or without TSH and incubated with [14C]mevalonate. Under TSH regulation, the level of the whole of dolichol components was increased 1.25-fold without modifying their distribution. Dolichol, and free and monosaccharide-linked dolichyl-phosphate, represented respectively 40% and 45% of total dolichol components while dolichyl-pyrophosphate-oligosaccharide represented 3% only. A marked enhancement (4.2-fold) of oligosaccharyltransferase activity occurred in stimulated cells, which could correspond to the addition of the two TSH effects: stimulation of Tg synthesis (3-fold) and of Tg glycosylation (1.5-fold). The amount of lipid carriers appeared to be insufficiently increased but no component is a limiting step, suggesting that the turnover of dolichol derivatives may be increased under TSH control through their use by higher amounts of Tg.
我们之前表明，在促甲状腺激素（TSH）刺激下，甲状腺球蛋白（Tg）的糖基化增强了1.5倍，这对应于每个Tg分子中寡糖链数量的增加。现在，已经对涉及多萜醇成分和寡糖基转移酶活性的步骤进行了研究。将猪甲状腺细胞培养在有或没有TSH的多孔底部滤器上，并用[14C]甲羟戊酸进行孵育。在TSH调节下，多萜醇成分的总量增加了1.25倍，但其分布没有改变。多萜醇、游离的和单糖连接的磷酸多萜醇分别占多萜醇成分总量的40%和45%，而焦磷酸多萜醇 - 寡糖仅占3%。在受刺激的细胞中，寡糖基转移酶活性显著增强（4.2倍），这可能对应于TSH的两种作用：刺激Tg合成（3倍）和刺激Tg糖基化（1.5倍）。脂质载体的量似乎增加不足，但没有成分是限制步骤，这表明在TSH控制下，通过大量Tg对多萜醇衍生物的利用，多萜醇衍生物的周转可能会增加。
