REGULATION OF THYROID FUNCTION BY TRANSCRIPTION FACTOR NF-kB

1) ACTH对大鼠转录因子表达的调控Ad4BP、NGFI-B和COUP-TF等转录因子已被证明与甾体源性细胞色素P450c21基因的启动子区域结合。因此，我们研究了ACTH是否通过调节这些转录因子的表达来增加肾上腺甾体生成。用药理学剂量的地塞米松处理大鼠，使其完全抑制ACTH的内源性分泌。每隔一段时间，用Northern blot和EMSA检测Ad4BP、NGFI-B和COUP-TF的表达。ACTH可导致NGFI-B mRNA的短暂升高，并在刺激后60分钟达到峰值。Ad4BP和COUP-TF mRNA水平未见变化。EMSA结果显示，ACTH可瞬间增加Ad4BP的DNA结合活性，表明ACTH通过磷酸化等翻译后修饰激活Ad4BP。更重要的是，ACTH可能通过调节这些转录因子来调节甾体生成。2) Ad4BP、NGFI-B、COUP-TF在人肾上腺皮质腺瘤中的表达研究了Ad4BP、NGFI-B、COUP-TF在3例库欣综合征和1例醛固酮产生型肾上腺皮质腺瘤中的表达。仔细分离腺瘤和邻近的非肿瘤组织，并在80℃下冷冻。从每个组织中提取的总RNA用于Northern blot分析。在库欣综合征患者中，Ad4BP和COUP-TF mRNA在肿瘤和邻近正常组织中的表达相同。而NGFI-B mRNA在正常组织中的表达高于肿瘤组织。在醛固酮产生性腺瘤患者中，肿瘤组织中未检测到Ad4BP mRNA，而正常邻近组织中存在Ad4BP mRNA。在肿瘤和正常组织中同样检测到NGFI-B和COUP-TF mrna。这些发现表明，参与类固醇生成P450基因调控的转录因子的表达改变可能是肾上腺皮质肿瘤中类固醇生成多样性的原因。3)肾上腺皮质腺瘤中促肾上腺皮质激素受体（ACTH- r）基因的表达研究7例库欣综合征患者。在正常组织中，ACTH-R mRNA几乎检测不到，而在肿瘤组织中，ACTH-R mRNA不变。由于ACTH- r mRNA在大鼠体内的表达需要ACTH，因此正常组织中ACTH mRNA未表达是由于库欣综合征患者抑制ACTH分泌所致。该受体mRNA在肿瘤组织中的表达提示其可能参与肿瘤中糖皮质激素合成异常的发病机制。少

1) REGULATION OF THE EXPRESSION OF TRANSCRPTION FACTORS BY ACTH IN RATTranscription factors such as Ad4BP,NGFI-B and COUP-TF have been shown to bind with the promoter region of the steroidogenic cytochrome P450c21 gene. We thus investigated whether ACTH increses adrenal steroidogenesis through regulation of the expression of these transcription factors. Rats were treated with pharmacological doses of dexamethasone to completely suppress the endogenous secretion of ACTH.At intervals after ACTH administration, expression of Ad4BP、NGFI-B and COUP-TF was evaluated by Northern blot analysis and electrophoretic mobility shift assay (EMSA).Administration of ACTH resulted in a transient increase in NGFI-B mRNA with a peak at 60 min post-stimulation. No change was observed in the levels of Ad4BP and COUP-TF mRNA.EMSA revealed that ACTH transiently increases DNA binding activity of Ad4BP,indicating that ACTH activates Ad4BP through post-translational modification such as phosphorylation.Futhermo … More re, it is demonstrated that ACTH may regulate steroidogenesis through modulation of these transcription factors.2) EXPRESSION OF Ad4BP、NGFI-B、COUP-TF IN HUMAN ADRENOCORTICAL ADENOMASExpression of Ad4Bp、NGFI-B、COUP-TF was studied in the adrenocortical adenomas obtained from 3 patients with Cushing's syndrome and 1 with aldosterone producing adenoma. Adenoma and adjacent non-tumor tissue were carefully separated and kept frozen at-80ﾟC.Total RNA extrated from each tissue was used for the Northern blot analysis. In patients with Cushing's syndrome, the expression of Ad4BP and COUP-TF mRNA was equally observed in the tumors and in the adjacent normal tissues. However, the expression of NGFI-B mRNA was more in the normal tissues than in the tumors. In the patients with aldosterone producing adenoma, Ad4BP mRNA was not detected in the tumor tissue, while it was present in the normal adjacent tissue. NGFI-B and COUP-TF mRNAs were equally detected in the tumor as well as in the normal tissue.These findings suggest that altered expression of the transcription factors involved in the regulation of steroidogenic P450 genes may be responsible for the multiplicity of steroidogenesis in adrenocortical tumors.3) EXPRESSION OF ACTH RECEPTOR (ACTH-R) GENES IN ADRENOCORTICAL ADENOMASSeven patients with Cushing's syndrome were studied. In normal tissues, ACTH-R mRNA was almost undetectable while it was invariabley detected in tumor tissues. Since ACTH is required for the expression of ACTH-R mRNA in rats, no expression of the mRNA in normal tissue is due to the inhibition of ACTH secretion in the patients with Cushing's synddrome. Expression of the receptor mRNA in the tumor tissue suggest that it may be involved in the pathogenesis of abnormal synthesis of glucocorticoid in the tumor. Less