Lewis E J, Harrington C A, Chikaraishi D M
Proc Natl Acad Sci U S A. 1987 Jun;84(11):3550-4. doi: 10.1073/pnas.84.11.3550.
Glucocorticoid and cyclic AMP increase tyrosine hydroxylase (TH) activity and mRNA levels in pheochromocytoma cultures. The transcriptional activity of the TH gene, as measured by nuclear run-on assay, is also increased when cultures are treated with the synthetic glucocorticoid dexamethasone or agents that increase intracellular cyclic AMP, such as forskolin and 8-BrcAMP. Both inducers effect transcriptional changes within 10 min after treatment and are maximal after 30 min for forskolin and after 60 min for dexamethasone. The 5' flanking sequences of the TH gene were fused to the bacterial gene chloramphenicol acetyltransferase (CAT), and the hybrid gene was transfected into pheochromocytoma cultures and GH4 pituitary cells. In both cell lines, a region of the TH gene containing bases -272 to +27 conferred induction of CAT by cyclic AMP, but not by glucocorticoid. The same results were found when a region of the TH gene containing -773 to +27 was used. Thus, the sequences required for induction of TH by cyclic AMP are contained within 272 bases of 5' flanking sequence, but sequences sufficient for glucocorticoid regulation are not contained within 773 bases.
糖皮质激素和环磷酸腺苷（cAMP）可增加嗜铬细胞瘤培养物中酪氨酸羟化酶（TH）的活性和mRNA水平。当用合成糖皮质激素地塞米松或增加细胞内环磷酸腺苷的试剂（如福斯可林和8-溴环磷酸腺苷）处理培养物时，通过核转录分析测定的TH基因转录活性也会增加。两种诱导剂在处理后10分钟内即可引起转录变化，福斯可林在30分钟后达到最大值，地塞米松在60分钟后达到最大值。将TH基因的5'侧翼序列与细菌氯霉素乙酰转移酶（CAT）基因融合，并将杂交基因转染到嗜铬细胞瘤培养物和GH4垂体细胞中。在这两种细胞系中，TH基因中包含-272至+27碱基的区域可被环磷酸腺苷诱导CAT表达，但不能被糖皮质激素诱导。当使用TH基因中包含-773至+27的区域时，也得到了相同的结果。因此，环磷酸腺苷诱导TH所需的序列包含在5'侧翼序列的272个碱基内，但糖皮质激素调节所需的序列不包含在773个碱基内。
