GROWTH FACTOR INVOLVEMENT IN PITUITARY FUNCTION

生长因子参与垂体功能

• 批准号: 2143122
• 负责人: Jeffrey E Kudlow
• 金额: $ 21.05万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 1991
• 资助国家: 美国
• 起止时间: 1991-06-01 至 1996-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2143122
• 关键词: DNA binding protein; DNA footprinting; dopamine agonists; epidermal growth factor; estrogens; gel electrophoresis; gene expression; genetic promoter element; genetic regulation; genetic regulatory element; genetic transcription; genetically modified animals; growth factor receptors; hormone regulation /control mechanism; hyperprolactinemia; in situ hybridization; laboratory mouse; molecular cloning; phorbols; pituitary gland; pituitary neoplasms; polymerase chain reaction; posttranslational modifications; prolactin; protein structure function; southern blotting; tissue /cell culture; transcription factor; transfection; transforming growth factors; ultraviolet radiation; western blottings

Prolactin secreting adenomata are a common cause of amenorrhea and infertility. tumors fortunately usually retain hormonal responsiveness such that their hormone production and growth can be controlled by the same hormones that modulate their normal counterparts. We have proposed that the growth of pituitary lactotrophs is regulated by growth factors whose expression in the pituitary gland is regulated hormonally. Previously we have localized transforming growth factor-alpha (TGFalpha) to lactotrophs and propose that this growth factor mediates the hormonal control of growth via the epidermal growth factor (EGF) receptor. Indeed, we have shown that estrogen-stimulated growth is preceded by an increase in TGFalpha mRNA in the pituitary while, bromergocryptine mediated growth inhibition is preceded by a decrease in TGFalpha mRNA. Our proposal is to enlarge upon these studies. Specifically, we propose to investigate the sites of TGFalpha expression in the pituitary and the modulation of its expression by estrogens and dopamine agonists using in situ hybridization. We also propose to develop transgenic mice in which TGFalpha overexpression is targeted to the lactotroph using the segments of the prolactin promoter which mediate- differing levels of tissue specific expression. These later studies will show whether TGFalpha stimulates lactotroph hyperplasia and hyperfunction. Finally, we have shown that TGFalpha expression is upregulated by phorbol esters and EGF. We have cloned 14 kb of the 5'-flanking region of the human TGFalpha gene of which a 1 kb proximal segment is capable of driving the expression of the luciferase reporter gene in MDA468 cells (human breast carcinoma cells). The 5'-promoter region of the TGFalpha gene is unusual in that it is G-C rich and does not contain typical TPA, EGF or estrogen response elements. On the other hand, it has striking similarity to the EGF receptor gene, which, in our systems, is coordinately regulated with the gene for its ligand, TGFalpha. We propose that these two genes use similar elements (cis- and trans-) to control their expression. Based on the structure of these genes, we believe these elements are distinct from the currently well characterized elements in other genes, raising the potential for the characterization of a novel transcription regulatory system. We plan to characterize the cis-acting elements in the TGFalpha gene that mediate phorbol ester and EGF responsiveness and to isolate and clone the proteins that interact with these elements. Together, the proposed studies will provide insight into the physiological role of TGFalpha in lactotroph, and form the basis for the understanding of its role and controlling mechanisms in other tissues.

催乳素分泌腺瘤是闭经和 不育。幸运的是，肿瘤通常保留这样的激素反应性 他们的激素产生和生长可以由相同的控制 调节其正常对应物的激素。 我们提出了 垂体乳腺营养的生长受生长因子的调节 垂体中的表达受到荷尔蒙调节。 以前我们 具有局部转化生长因子-Alpha（TGFALPHA）到乳营养素 并提出该生长因子介导了生长的激素控制 通过表皮生长因子（EGF）受体。 确实，我们已经表明 在雌激素刺激的生长之前，tgfalpha mRNA在 垂体同时，溴加元介导的生长抑制是 在TGFALPHA mRNA的降低之前。 我们的建议是扩大 这些研究。 具体来说，我们建议调查 垂体中的tgfalpha表达及其表达的调制 通过使用原位杂交的雌激素和多巴胺激动剂。 我们也是 建议开发转基因小鼠，其中tgfalpha过表达为 使用催乳素启动子的片段针对乳酸营养 哪些介导的组织特异性表达水平不同。 这些以后 研究将显示TGFALPHA是否刺激乳腺营养增生和 功能过高。 最后，我们表明tgfalpha表达是 由凤凰酯和EGF上调。 我们已经克隆了14公里的 人类tgfalpha基因的5'-频偏区，其中1 kb近端 细分市场能够驱动荧光素酶报告器的表达 MDA468细胞（人乳腺癌细胞）中的基因。 5'Promoter tgfalpha基因的区域是不寻常的，因为它富含g-c 包含典型的TPA，EGF或雌激素反应元件。 另一方面， 它与EGF受体基因具有惊人的相似性，在我们的系统中 与该基因的配体TGFALPHA协调调节。 我们 提出这两个基因使用相似的元素（顺式和反式）与 控制他们的表达。 基于这些基因的结构，我们 认为这些元素与当前的特征不同 其他基因的元素，提高了表征的潜力 一种新型的转录调节系统。 我们计划表征 TGFALPHA基因中介导Phorbol酯和EGF的顺式作用元素 响应能力并隔离和克隆与之相互作用的蛋白质 这些元素。 拟议的研究将共同​​洞悉 tgfalpha在乳酸营养中的生理作用，构成了 对其作用和控制机制的理解。