GROWTH FACTOR INVOLVEMENT IN PITUITARY FUNCTION

分泌催乳素的腺瘤是闭经和 不孕不育。幸运的是，肿瘤通常会保留荷尔蒙反应性 它们的荷尔蒙分泌和生长可以由同样的 调节正常的荷尔蒙。我们已经提议 垂体促乳素细胞的生长受生长因子的调节，这些生长因子 脑下垂体的表达受荷尔蒙的调节。以前我们 已将转化生长因子-α(TGFα)定位为乳酸菌 并提出这种生长因子介导了激素对生长的控制。 通过表皮生长因子(EGF)受体。事实上，我们已经证明了 在雌激素刺激的生长之前，脑组织中TGFαmRNA的增加 而在脑垂体，溴汞隐亭介导的生长抑制是 随之而来的是TGFpha基因表达的降低。我们的建议是扩大对 这些研究。具体地说，我们建议调查 转化生长因子α在垂体中的表达及其调控 通过雌激素和多巴胺激动剂进行原位杂交。我们也 建议发展转化生长因子α过表达的转基因小鼠 利用催乳素启动子片段靶向催乳素 它们调节不同水平的组织特异性表达。这些是后来的 研究将表明，转化生长因子α是否刺激催乳素增生和 机能亢进。最后，我们已经证明了TGFAlpha表达式是 佛波醇酯和EGF上调。我们已经克隆了14kb的 人转化生长因子α基因的5‘侧翼区，其近端为1kb 片段能够驱动荧光素酶报告基因的表达 MDA468细胞(人乳腺癌细胞)中的基因。5‘-启动子 TGFpha基因的区域是不寻常的，因为它富含G-C，而不是 含有典型的TPA、EGF或雌激素反应成分。另一方面， 它与EGF受体基因有惊人的相似性，在我们的系统中， 与其配体TGFpha的基因协调调节。我们 建议这两个基因使用相似的元件(顺式和反式)来 控制他们的表情。基于这些基因的结构，我们 我相信这些元素不同于目前很好的特征 其他基因中的元素，提高了表征 一种新的转录调控系统。我们计划将其描述为 转化生长因子α基因中调节佛波酯和表皮生长因子的顺式作用元件 并分离和克隆与之相互作用的蛋白质 这些元素。总之，拟议的研究将提供对 TGFα在乳酸菌中的生理作用，并形成了 对其在其他组织中的作用和调控机制的理解。

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.