Murata Y, Seo H, Sekiguchi K, Imai T, Lee J, Matsui N
Research Institute of Environmental Medicine, Nagoya University, Japan.
Mol Endocrinol. 1990 May;4(5):693-9. doi: 10.1210/mend-4-5-693.
The regulation of fibronectin (FN) gene expression by thyroid hormone was studied. Rats were rendered hypothyroid by thyroidectomy, and the administration of T4 or T3 was used to produce rats in various thyroid states. RNA was extracted from fresh liver, kidney, and heart, and FN mRNA was determined by dot blot hybridization with a 32P-labeled rat FN cDNA probe. The specificity of the hybridization was assessed by Northern blot analysis. In liver, thyroidectomy decreased the abundance of FN mRNA by half, and daily administration of physiological doses of T4 or T3 for 5-6 days restored FN mRNA to the control level. The administration of pharmacological doses of thyroid hormones induced a further increase in the abundance of FN mRNA. A significant dose-dependent correlation between serum levels of T4 and the abundance of FN mRNA was observed in liver. A receptor-saturating dose of T3 (200 micrograms) given to thyroidectomized rats produced a significant increase in FN mRNA within 6 h after injection, indicating that expression of the FN gene was induced relatively rapidly. Moreover, a nuclear run-off assay revealed that thyroid hormone induces expression of the FN gene at least in part at a transcriptional level. The amount of FN mRNA was also determined in kidney and heart of the same rats. Although the abundance of FN mRNA changed by thyroidectomy or the administration of thyroid hormone in those organs, the magnitude of changes were slight compared with those observed in liver. These results suggested that a marked and dose-dependent induction of the FN gene by thyroid hormone occurs specifically in liver.(ABSTRACT TRUNCATED AT 250 WORDS)
研究了甲状腺激素对纤连蛋白（FN）基因表达的调控。通过甲状腺切除术使大鼠甲状腺功能减退，给予T4或T3以产生处于不同甲状腺状态的大鼠。从新鲜的肝脏、肾脏和心脏中提取RNA，并用32P标记的大鼠FN cDNA探针通过斑点杂交法测定FN mRNA。通过Northern印迹分析评估杂交的特异性。在肝脏中，甲状腺切除术使FN mRNA的丰度降低了一半，每天给予生理剂量的T4或T3 5 - 6天可使FN mRNA恢复到对照水平。给予药理剂量的甲状腺激素可导致FN mRNA丰度进一步增加。在肝脏中观察到血清T4水平与FN mRNA丰度之间存在显著的剂量依赖性相关性。给甲状腺切除的大鼠注射受体饱和剂量的T3（200微克），在注射后6小时内FN mRNA显著增加，表明FN基因的表达诱导相对迅速。此外，核转录分析表明甲状腺激素至少部分在转录水平诱导FN基因的表达。还测定了同一批大鼠肾脏和心脏中的FN mRNA量。尽管甲状腺切除术或给予甲状腺激素会使这些器官中FN mRNA的丰度发生变化，但与肝脏中观察到的变化相比，变化幅度较小。这些结果表明，甲状腺激素对FN基因的显著且剂量依赖性诱导特异性地发生在肝脏中。（摘要截短至250字）
