REGULATION OF TRH GENE EXPRESSION IN NEUROENDOCRINE CELL

促甲状腺激素释放激素（TRH）在肿瘤的发生发展中起着关键作用。 促甲状腺激素（TSH）分泌的下丘脑调节 垂体前叶并广泛分布于下丘脑外 神经内分泌组织 虽然这种神经肽在神经系统中起着关键作用， 神经元和内分泌系统之间的信息转导，很少 目前已知TRH基因表达调控因子。 DNA序列鉴定及反式作用因子cDNA的克隆 调节TRH基因表达的蛋白质将提供大量的见解， 神经肽激素在正常和异位子宫内膜表达的机制 分泌激素的神经内分泌细胞。 该方案的主要目的是：1）鉴定顺式作用DNA 决定TRH基因的组织特异性表达的序列，2） 表征与TRH序列结合的反式作用因子 3）分离并测序编码该蛋白的cDNA， TRH反式作用因子。 我的初步结果表明TRH -47 ~-113 bp的片段对TRH基因表达有重要作用。 在这个片段中有两个序列与组织同源- 生长抑素（SS）基因的特异性/cAMP增强子（TSE/CRE）。 研究 这些元件及其周围的核苷酸表明它们可以作为 增强子元件，并受到DNA酶核提取物中因子的保护 我的足迹分析。 足迹分析与竞争研究 证明TRH-蛋白质复合物可以与 SS启动子元件的TRH。 序列同源性 由神经肽基因TRH和SS，表明这些同源 元件可能是反式作用因子的结合位点， 不同的神经内分泌细胞和异位神经肽分泌肿瘤。 分泌TRH和SS的甲状腺髓样癌细胞系CA 77， 提供了一个理想的模型来测试理论， 因子可以调节两种神经肽基因的表达。 阐明细胞和分子机制的基础上， TRH基因的表达将增加我们对控制 垂体-甲状腺轴的分子基础 肽激素在神经内分泌细胞中的表达。

Thyrotropin releasing hormone (TRH) plays a pivotal role in the hypothalamic regulation of thyroid stimulating hormone (TSH) secretion from the anterior pituitary and is widely distributed in extrahypothalamic neuroendocrine tissues. Although this neuropeptide plays a key role in the transduction of information between neuronal and endocrine systems, little is known about the factors that regulate TRH gene expression. Identification of the DNA sequence and cloning the trans-acting factor cDNA that regulates TRH gene expression would provide a great deal of insight into the mechanism of neuropeptide hormone expression in normal and ectopic hormone secreting neuroendocrine cells. The major aims of this proposal are to 1) identify the cis-acting DNA sequences that determine tissue-specific expression of the TRH gene, 2) characterize the trans-acting factor(s) that bind to the TRH sequences important for gene expression, 3) isolate and sequence a cDNA encoding the TRH trans-acting factor. My preliminary results demonstrate that the TRH fragment between -47 and -113 bp is important for TRH gene expression. Within this fragment are two sequences that are homologous to the tissue- specific/cAMP enhancer (TSE/CRE) of the somatostatin (SS) gene. Studies of the elements with its surrounding nucleotides suggest they can function as enhancer elements and are protected by factors in nuclear extracts in DNase I footprinting assays. Footprinting assays with competition studies demonstrate that the TRH-protein complex can be dissociated equally with either the TRH of the SS promoter element. The sequence homologies shared by the neuropeptide genes, TRH and SS, suggest that these homologous elements might be binding sites for trans-acting factors shared by different neuroendocrine cells and ectopic neuropeptide secreting tumors. The TRH and SS secreting medullary thyroid carcinoma cell line, CA77, provides and ideal model to test the theory that a single trans-acting factor can regulate the expression of both neuropeptide genes. Elucidation of the cellular and molecular mechanisms underlying the expression of the TRH gene will increase our understanding of the control of the pituitary-thyroid axis by the brain and the molecular basis of peptide hormone expression in neuroendocrine cells.