Structural Basis of Prolactin Receptor Recognition

描述(由申请人提供)：这一长期项目的总体目标是描绘与催乳素受体识别和信号转导有关的特定结构和功能相互作用。虽然最著名的传统角色是垂体源性激素，但最近的研究已经确定了催乳素在各种组织的生长和发育中具有重要的自分泌/旁分泌功能。催乳素及其细胞表面受体在多种人乳腺癌细胞系和前列腺癌细胞系中均有表达。催乳素在这些肿瘤中具有促有丝分裂和血管生成功能，并增加癌细胞的运动性。外周催乳素的生物学合成不同于脑下垂体，包括转录调节、RNA剪接以及激素储存和分泌的替代机制。此外，当从周围组织分离时，或在培养中生长的非垂体细胞系产生时，发现催乳素的糖基化和磷酸化变体。研究已经证明了这些修饰的功能后果，其中一些可能起到对抗天然催乳素的致瘤作用。同样，在健康和恶性组织中都描述了催乳素受体的多种异构体。这些受体亚型对催乳素的亲和力不同，对细胞内信号转导通路的激活也不同。 这一应用的中心假设是，催乳素残基的不同亚群是催乳素及其变体对催乳素受体亚型表现出的不同识别特异性的原因。我们将使用核磁共振波谱在原子水平上识别负责受体识别特异性的精确的分子间相互作用。这些相互作用的功能意义将通过受体结合动力学的测量以及细胞激活和信号转导的分析来研究。通过对野生型和变异型催乳素的比较，我们希望揭示受体激动型和拮抗型的分子机制。拟议的研究结果将有助于开发潜在的治疗剂，旨在调节催乳素的特定活动，包括催乳素受体拮抗剂，这将对乳腺癌、前列腺癌和潜在的其他癌症的治疗具有重要意义。

DESCRIPTION (provided by applicant): The overall goal of this long-term project is to delineate the specific structural and functional interactions involved in prolactin receptor recognition and signal transduction. Although best known for its traditional role as a pituitary-derived hormone, recent research has established important autocrine/paracrine functions of prolactin in the growth and development of a diversity of tissues. Expression of prolactin and its cell-surface receptor has been demonstrated in multiple human breast and prostate cancer cell lines. Prolactin has mitogenic and angiogenic function in these tumors and increases cancer cell motility. The biology of peripheral prolactin synthesis is distinct from the pituitary, including alternative mechanisms for transcriptional regulation, RNA splicing, and hormone storage and secretion. Additionally, when isolated from peripheral tissue, or when produced by non-pituitary cell lines grown in culture, glycosylated and phosphorylated variants of prolactin are found. Research has demonstrated functional consequences of these modifications, some of which may act to counter the tumorigenic effects of native prolactin. Similarly, multiple isoforms of the prolactin receptor have been described in both healthy and malignant tissue. These receptor isoforms differ in their affinity for prolactin and in their activation of intracellular signal transduction pathways. The central hypothesis of this application states that distinct subsets of prolactin residues are responsible for the differences in recognition specificity displayed by prolactin and its variants towards prolactin receptor isoforms. We will use NMR spectroscopy to identify, at an atomic level, the precise intermolecular interactions responsible for receptor recognition specificity. The functional significance of these interactions will be investigated by measurement of receptor binding kinetics and assays of cellular activation and signal transduction. By comparison of the wild type and variant forms of prolactin, we hope to uncover the molecular mechanisms for both receptor agonism and antagonism. The results of the proposed research will aid the development of potential therapeutic agents designed to modulate specific activities of prolactin, including prolactin receptor antagonists, which will have significance for the treatment of breast, prostate and, potentially, other cancers.