REGULATION OF THYROID FUNCTION BY TRANSCRIPTION FACTOR NF-kB

1)ACTH对转录因子表达的调节作用已证实Ad4BP、NGFI-B和COUP-Tf等转录因子与类固醇生成细胞色素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类固醇激素的生成。用药理剂量的地塞米松完全抑制大鼠ACTH的内源性分泌。给予ACTH后，用Northern印迹分析和凝胶迁移率改变分析检测Ad4BP、、NGFI-B和COUP-Tf的表达。EMSA结果显示，促肾上腺皮质激素能瞬时增强Ad4BP的…结合活性，提示促肾上腺皮质激素通过翻译后修饰，如磷酸化，激活Ad4BP。2)Ad4BP、NGFI-B、Coup-Tf在人肾上腺皮质腺瘤中的表达研究Ad4Bp、NGFI-B、Coup-Tf在3例库欣综合征和1例醛固酮腺瘤中的表达。将腺瘤及癌旁组织仔细分离，冷冻至-80ﾟC，提取总RNA进行Northern杂交分析。在库欣综合征患者中，Ad4BP和COUP-TFm RNA在肿瘤组织和癌旁正常组织中的表达相同。而NGFI-bmRNA在正常组织中的表达高于肿瘤组织。在醛固酮腺瘤患者中，肿瘤组织中未检测到Ad4BP mRNA，而癌旁正常组织中有Ad4BP mRNA表达。NGFI-B和COUP-TFmRNAs在肿瘤和正常组织中均有表达。这些结果提示参与类固醇生成P450基因调控的转录因子的表达变化可能是肾上腺皮质肿瘤类固醇生成多样性的原因。3)研究了7例库欣综合征患者肾上腺皮质ACTH受体(ACTH-R)基因的表达。在正常组织中几乎检测不到ACTH-R基因，而在肿瘤组织中检测不到。由于大鼠ACTH-R基因的表达需要ACTH，库欣综合征患者ACTH分泌受到抑制，导致正常组织中ACTH-R基因不表达。该受体在肿瘤组织中的表达提示其可能参与了肿瘤糖皮质激素异常合成的发病机制。较少

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