Theriault A, Ogbonna G, Adeli K
Department of Chemistry and Biochemistry, University of Windsor, Ontario, Canada.
Biochem Biophys Res Commun. 1992 Jul 31;186(2):617-23. doi: 10.1016/0006-291x(92)90791-i.
We have investigated the modulation of apolipoprotein B gene expression in HepG2 cells by thyroid hormone. ApoB secretion rate in serum-free media was found to be significantly increased in the presence of the hormone in long-term cultures (48 h, 37%). This stimulatory effect was dose-dependent. The mechanisms underlying the stimulatory effect of triiodothyronine on apoB production were investigated. Triiodothyronine increased apoB mRNA levels by about 25-36% as determined by slot- and Northern-blot analysis of total RNA. ApoB synthesis rate was also found to be increased both in in vivo pulse-chase experiments (61%) and in in vitro translation studies (54.5%). Despite the 54.5-61% increase in apoB synthesis with triiodothyronine, only a 30% increase in apoB secretion was noted suggesting that part of the increase in the intracellular apoB pool may be lost by degradation. Overall, apoB gene expression appears to be modulated by thyroid hormone at both transcriptional and posttranscriptional levels.
我们研究了甲状腺激素对HepG2细胞中载脂蛋白B基因表达的调节作用。在长期培养（48小时，37%）且存在该激素的情况下，发现无血清培养基中的载脂蛋白B分泌率显著增加。这种刺激作用具有剂量依赖性。研究了三碘甲状腺原氨酸对载脂蛋白B产生刺激作用的潜在机制。通过对总RNA进行狭缝印迹和Northern印迹分析确定，三碘甲状腺原氨酸使载脂蛋白B mRNA水平增加了约25%-36%。在体内脉冲追踪实验（61%）和体外翻译研究（54.5%）中也发现载脂蛋白B合成率增加。尽管三碘甲状腺原氨酸使载脂蛋白B合成增加了54.5%-61%，但仅观察到载脂蛋白B分泌增加了30%，这表明细胞内载脂蛋白B池增加的部分可能因降解而损失。总体而言，载脂蛋白B基因表达似乎在转录和转录后水平均受到甲状腺激素的调节。
