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Regulatory mechanism of gene expression of peptide (SRIF and TRH) receptors

肽（SRIF和TRH）受体基因表达的调控机制

基本信息

批准号：
06670095
负责人：
KIMURA Nobuko
金额：
$ 1.15万
依托单位：
TOKYO METROPOLITAN INSTITUTE FOR NEUROSCIENCE
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

Estrogen (E_2) not only up-regulates the binding acitivity of Somatostatin (SRIF) receptors but also increases transcriptionally Thyrotropin-releasing hormone (TRH) receptors in the pitutary cells.The aim of this study is to determine the subtypes of SRIF receptors regulated by E_2 to elucidate the action mechanism of E_2 on the binding activity of these peptide hormone receptors at the transcriptional level, and to know the cis-elements of TRH receptor gene at 5'flanking region.The results were ; (1) E_2 up-regulated mRNA levels of SRIF recetor subtypes (SSTR1 and SSTR2) in different ways in GH_3 cells, which occurred without ongoing protein synthesis.(2) Competitive reverse transcription-polymerase chain reaction (RT-PCR) used to obtain the quantitative values of mRNA levels of 5 SRIF receptor subtypes in the pituitary primary clutured cells revealed that large amounts of SSTR2 and SSTR3 mRNA were expressed inprimary cultured cells, whereas SSTR1 and SSTR2 mRNA in GH3 cells.In primary clutured cells E_2 primarily increased the mRNA levels of SSTR2 and SSTR3, and affected weakly SSTR1 mRNA level.(3) In an attempt to understand the transciptional control of pituitary peptide receptors by E_2, we have determined the nucleotide sequence of approximately 1.1kb of 5'flanking region of the TRH receptor.Although no typical TATA box was identified, a number of promotor elements was identified, including GCF,AP1, AP2, half GRE,half TRE consensus sequences.The absence of ERE consensus sequence in the 5'flanking region of the receptor suggests that E_2 effect is mediated by the AP1 site possibly as a result of the cooperative action of E_2 receptor and a certain type of transcription factors.

雌激素（E_2）不仅上调生长抑素（SRIF）受体的结合活性，而且还可以转录增加垂体细胞中促甲状腺激素释放激素（TRH）受体的结合活性。本研究的目的是确定E_2调节的SRIF受体的亚型，以阐明E_2对这些肽激素结合活性的作用机制转录水平上的受体，并了解TRH受体基因5'侧翼区的顺式元件。 (1) E_2 在 GH_3 细胞中以不同方式上调 SRIF 受体亚型 (SSTR1 和 SSTR2) 的 mRNA 水平，这种情况在没有持续蛋白质合成的情况下发生。 (2) 用于获得垂体原代培养细胞中 5 种 SRIF 受体亚型 mRNA 水平的竞争性逆转录聚合酶链反应 (RT-PCR) 定量值表明，大量 SSTR2和SSTR3 mRNA在原代培养细胞中表达，而SSTR1和SSTR2 mRNA在GH3细胞中表达。在原代培养细胞中，E_2主要增加SSTR2和SSTR3 mRNA水平，并且对SSTR1 mRNA水平影响较弱。(3)为了了解E_2对垂体肽受体的转录控制，我们确定了大约E_2的核苷酸序列 TRH受体5'侧翼区1.1kb。虽然没有鉴定出典型的TATA盒，但鉴定出了许多启动子元件，包括GCF、AP1、AP2、半GRE、半TRE共有序列。受体5'侧翼区缺乏ERE共有序列，表明E_2效应是由AP1位点介导的，可能是由于 E_2受体和某种类型的转录因子。