Structural Basis of Prolactin Receptor Recognition

描述（由申请人提供）：这个长期项目的总体目标是描述催乳素受体识别和信号转导中涉及的特定结构和功能相互作用。虽然最广为人知的是其作为垂体衍生激素的传统作用，但最近的研究已经确定催乳素在多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的表达已在多种人乳腺癌和前列腺癌细胞系中得到证实。催乳素在这些肿瘤中具有有丝分裂和血管生成功能，并增加癌细胞的运动性。外周催乳素合成的生物学与垂体不同，包括转录调节、RNA剪接和激素储存和分泌的替代机制。此外，当从外周组织分离或由培养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，其中一些可能对抗天然催乳素的致瘤作用。类似地，在健康和恶性组织中都发现了催乳素受体的多种异构体。这些受体异构体对催乳素的亲和力和对细胞内信号转导途径的激活不同。

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.