IGF-1 Receptor Signaling in Mammary Gland Development

乳腺发育中的 IGF-1 受体信号传导

• 批准号: 6709357
• 负责人: DARRYL L HADSELL
• 金额: $ 26.34万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-01-24 至 2007-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6709357
• 关键词: biological signal transduction; cell proliferation; confocal scanning microscopy; estradiol; gene targeting; genetically modified animals; growth factor receptors; hormone regulation /control mechanism; insulin; insulinlike growth factor; laboratory mouse; mammary epithelium; mammary gland; menstrual cycle; phosphorylation; pregnancy; progesterone

DESCRIPTION (provided by applicant): The cells of the terminal end bud (TEB) are the most proliferative and invasive cells found during postnatal development in mammals. These cells, through their enormous proliferative capacity, drive the development of the entire mammary ductal system, serve as a source of mammary progenitor cells, and are the single most important target for carcinogens within the mammary gland. The ability of endocrine-, paracrine- and extracellular matrix-derived signals to harness this enormous regenerative potential and direct it into a highly ordered developmental pattern makes the TEB both an important and very fascinating system with which to study the endocrine regulation of intracellular signaling. Our analysis of grafted mammary tissue from a knockout mouse model has demonstrated that a targeted inactivating mutation of the gene for the IGF-I receptor (lgf1r) dramatically reduces mammary ductal development and decreases TEB cell proliferation(1). This proliferative defect, however, is partial restored by early pregnancy. In breast cancer cell models the IGF-I receptor as well as a handful of other hormone receptors signal through insulin receptor substrate (IRS) proteins, and two serine threonine kinases, ERK and Akt. The overall hypothesis addressed in this proposal is that IGF-I receptor stimulates TEB cell proliferation through insulin responsive substrate (IRS)-dependent activation of ERK and Akt during virgin ductal development and that pregnancy or the ovarian steroid hormones estradiol (E2) and progesterone (P) increase the sensitivity of IRS-dependent signaling pathways to insulin receptor-dependent activation in Igf1r-/- TEB. Through the use confocal microscopy with recently developed antibodies to detect cell signaling in-situ, we will learn how signaling pathways are regulated in TEBs and what the significance of these pathways is to processes important to both normal mammary gland function and breast cancer. The specific aims are; 1) determine if estrus cycle, ovarectomy, early pregnancy, or exogenous E2+P alters IGF-I-, or insulin-induced phosphorylation of IRS-1, -2, ERK and Akt in mammary glands of normal mice, 2) determine if IGF-IR or IR dependent activation of ERK, and Akt is attenuated in the TEB of lgf1r -/- grafts and if early pregnancy or exogenous E2+P can restore this activation, and 3) determine if overexpression of IRS-1 or IRS-2 within the mammary epithelium restores development of Igf1r-/- mammary epithelium and enhances insulin-dependent posphorylation of ERK and Akt.

描述（由申请人提供）： 终芽（TEB）细胞是哺乳动物出生后发育过程中发现的最具增殖性和侵袭性的细胞。这些细胞通过其巨大的增殖能力，驱动整个乳腺导管系统的发育，作为乳腺祖细胞的来源，并且是乳腺内致癌物的最重要的单一目标。内分泌、旁分泌和细胞外基质衍生信号能够利用这种巨大的再生潜力并将其引导至高度有序的发育模式，这使得 TEB 成为研究细胞内信号传导的内分泌调节的重要且非常迷人的系统。我们对基因敲除小鼠模型移植乳腺组织的分析表明，IGF-I 受体 (lgf1r) 基因的靶向失活突变可显着降低乳腺导管发育并降低 TEB 细胞增殖 (1)。然而，这种增殖缺陷可以通过早期妊娠部分恢复。在乳腺癌细胞模型中，IGF-I 受体以及一些其他激素受体通过胰岛素受体底物 (IRS) 蛋白和两种丝氨酸苏氨酸激酶 ERK 和 Akt 发出信号。该提案提出的总体假设是，在处女导管发育过程中，IGF-I 受体通过胰岛素反应底物 (IRS) 依赖性 ERK 和 Akt 激活来刺激 TEB 细胞增殖，并且妊娠或卵巢类固醇激素雌二醇 (E2) 和孕酮 (P) 会增加 IRS 依赖性信号通路对胰岛素受体依赖性激活的敏感性。 Igf1r-/- TEB。通过使用共聚焦显微镜和最近开发的抗体来原位检测细胞信号传导，我们将了解 TEB 中如何调节信号传导通路，以及这些通路对正常乳腺功能和乳腺癌的重要过程有何意义。具体目标是； 1) 确定发情周期、卵巢切除、早期妊娠或外源性 E2+P 是否会改变正常小鼠乳腺中的 IGF-I- 或胰岛素诱导的 IRS-1、-2、ERK 和 Akt 磷酸化，2) 确定 IGF-IR 或 IR 依赖性 ERK 和 Akt 激活是否在 lgf1r -/- 移植物的 TEB 中减弱，如果 妊娠早期或外源性 E2+P 可以恢复这种激活，3) 确定乳腺上皮内 IRS-1 或 IRS-2 的过度表达是否会恢复 Igf1r-/- 乳腺上皮的发育并增强 ERK 和 Akt 的胰岛素依赖性磷酸化。