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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)不仅能上调生长抑素(SRIF)受体的结合活性，还能在转录水平上增加促甲状腺激素释放激素(TRH)受体的转录活性。本研究的目的是确定雌激素调节的SRIF受体亚型，从转录水平上阐明E_2对这些多肽受体结合活性的作用机制，并了解TRH受体基因5‘侧翼区的顺式元件。(1)在GH_3细胞中，E_2以不同的方式上调SRIF受体亚型(SSTR1和SSTR2)的mRNA水平，这种上调不发生在持续的蛋白质合成过程中。(2)竞争性逆转录-聚合酶链式反应(RT-PCR)检测了原代培养的垂体细胞中5种SRIF受体亚型的mRNA水平，发现原代培养细胞中有大量的SSTR2和SSTR3mRNA表达，而GH_3细胞中SSTR1和SSTR2的mRNA表达水平较高。(3)为了了解E_2对垂体肽受体的转录调控作用，我们测定了TRH受体5‘侧翼区约1.1kb的核苷酸序列，虽然没有发现典型的TATA盒，但发现了一些启动子元件，包括GCF、AP1、AP2、半GRE、半TrE等。在受体的5’侧翼区没有ERE共同序列，提示E_2的作用可能是由E_2受体和某些转录因子协同作用的结果。