ENDOTHELIN-1 IN NORMAL AND PATHOLOGICAL BONE REMODELING

内皮素-1 在正常和病理性骨重建中的作用

• 批准号: 7005690
• 负责人: THERESA A GUISE
• 金额: $ 29.78万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7005690
• 关键词: biological signal transduction; bone density; bone development; endothelin; enhancer binding protein; gene expression; genetically modified animals; hormone receptor; hormone regulation /control mechanism; hypogonadism; interleukin 6; intermolecular interaction; laboratory mouse; osteoblasts; pathologic bone resorption; physiologic bone resorption; secretion; sex hormones; steroid hormone metabolism; transcription factor

DESCRIPTION (provided by applicant): Endothelin-1 (ET-1) can cause osteoblastic bone metastases, stimulating dysregulated new bone formation by activating the endothelin A receptor (ETAR) on the osteoblast. The role of ET-1 in normal bone development, growth and remodeling is unclear. Our preliminary data indicate that: 1) ET-I is a potent stimulator of osteoblast activity and new bone formation in vivo; 2) Tumor-produced ET-1 stimulates osteoblastic metastases via ETAR; 3) ETAR blockade has sex steroid-dependent effects on bone mass: most strikingly, ETAR blockade reduces bone mass in hypogonadal but increases bone mass in intact female mice. 4) ET-1 increases expression of bone active factors IL-6 and Cyr61 and decreases that of Dkkl in osteoblasts, while increasing expression of the transcription factors C/EBPdelta and TSC-22. ET-1 did not alter EGFR activation or VEGF. The following hypotheses will be tested: 1) ET-1 plays an important role in normal bone remodeling. 2) ET-1 mediates effects on osteoblasts by changing the secretion of paracrine regulators 1L-6, Dkk1 and potentially Cyr61. 3) ET-1 increases the osteoblast transcription factor C/EBP\delta that interacts with Runx2, and TGFbeta-regulated TSC-22. 4) ETAR blockade results in reduced osteoblastic bone formation and increased osteoclast activity and may accelerates the osteoclastic bone resorption and subsequent bone loss associated with sex steroid deficiency. 5) Estrogen suppresses ET-1 synthesis. In estrogen-deficient states, increased ET-1 maintains bone mass Three Specific Aims are proposed: Aim 1: Determine the role of ET-1 and ETAR in normal bone development, growth, and remodeling 1A. Determine bone phenotype of mice with ETAR-null osteoblasts 1B. Determine bone phenotype of mice with ET-l- overexpressing osteoblasts Aim 2: Determine the role of ET-1 and ETAR in bone remodeling in sex-steroid deficient states 2A. Determine interactions between sex steroids and ET-1 in osteoblastic new bone formation 2B. Determine effects of combined inhibition of resorption and ETAR signaling on bone mass 2C. Determine bone phenotype of hypogonadal mice with ETAR-null or ET-1 ++g osteoblasts Aim 3: Determine the molecular mechanisms of ET-1 effects on bone 3A. Determine if ET-1 mediates its effects on osteoblasts via secreted IL-6, Dkk1, or Cyr61 3B. Determine effects of ET-1 on osteoblast transcription factors C/EBPdelta and TSC-22 3C. Determine major signaling pathways activated by ET-1 in osteoblasts 3D. Assess the interactions of sex steroids with ET-1 in bone cells The physiological role of ET-1 and ETAR in normal bone homeostasis needs investigation. 1, ETAR blockade is in clinical trials for many disease states, but the consequences for bone are unknown. Cancer patients treated with chronic ETAR blockade may suffer increased bone loss, in addition to that caused by sex-steroid deficiency. We will define the mechanisms and determine if this effect can be attenuated by bisphosphonate treatment. 2, an understanding of ET-1 activation of ETAR in the osteoblast may lead to new anabolic therapies for low bone mass. The experiments proposed will use in vivo and in vitro approaches to test the role of ET-1 activation of osteoblast ETAR in bone growth and remodeling.

描述（由申请人提供）：内皮素-1 (ET-1) 可引起成骨细胞骨转移，通过激活成骨细胞上的内皮素 A 受体 (ETAR) 刺激失调的新骨形成。 ET-1 在正常骨骼发育、生长和重塑中的作用尚不清楚。我们的初步数据表明：1）ET-I是体内成骨细胞活性和新骨形成的有效刺激剂； 2）肿瘤产生的ET-1通过ETAR刺激成骨细胞转移； 3) ETAR 阻断对骨量具有性类固醇依赖性作用：最引人注目的是，ETAR 阻断减少了性腺功能减退症的骨量，但增加了完整雌性小鼠的骨量。 4)ET-1增加成骨细胞中骨活性因子IL-6和Cyr61的表达并降低Dkkl的表达，同时增加转录因子C/EBPdelta和TSC-22的表达。 ET-1 不会改变 EGFR 激活或 VEGF。 将测试以下假设： 1) ET-1在正常骨重建中发挥重要作用。 2) ET-1 通过改变旁分泌调节因子 1L-6、Dkk1 和潜在的 Cyr61 的分泌来介导对成骨细胞的影响。 3) ET-1 增加与 Runx2 相互作用的成骨细胞转录因子 C/EBPδ 和 TGFbeta 调节的 TSC-22。 4) ETAR阻断导致成骨细胞骨形成减少和破骨细胞活性增加，并且可能加速破骨细胞骨吸收和随后与性类固醇缺乏相关的骨丢失。 5) 雌激素抑制ET-1合成。在雌激素缺乏的状态下，增加 ET-1 可以维持骨量 提出了三个具体目标： 目标 1：确定 ET-1 和 ETAR 在正常骨骼发育、生长和重塑中的作用 1A。确定具有 ETAR 无效成骨细胞的小鼠的骨表型 1B.确定具有 ET-1 过表达成骨细胞的小鼠的骨表型 目标 2：确定 ET-1 和 ETAR 在性类固醇缺乏状态下骨重塑中的作用 2A。确定性类固醇和 ET-1 在成骨细胞新骨形成中的相互作用 2B。确定吸收抑制和 ETAR 信号传导联合抑制对骨量的影响 2C。确定具有 ETAR-null 或 ET-1 ++g 成骨细胞的性腺功能减退小鼠的骨表型 目标 3：确定 ET-1 对骨影响的分子机制 3A。确定 ET-1 是否通过分泌的 IL-6、Dkk1 或 Cyr61 介导其对成骨细胞的影响 3B.确定 ET-1 对成骨细胞转录因子 C/EBPdelta 和 TSC-22 的影响 3C。确定成骨细胞中 ET-1 激活的主要信号通路 3D。评估性类固醇与骨细胞中 ET-1 的相互作用 ET-1 和 ETAR 在正常骨稳态中的生理作用需要研究。 1、ETAR 阻断正在针对多种疾病状态进行临床试验，但对骨骼的影响尚不清楚。除了性类固醇缺乏引起的骨质流失之外，接受长期 ETAR 阻断治疗的癌症患者可能还会遭受更多的骨质流失。我们将定义其机制并确定是否可以通过双膦酸盐治疗来减弱这种效应。如图 2 所示，了解成骨细胞中 ETAR 的 ET-1 激活可能会导致针对低骨量的新合成代谢疗法。拟议的实验将使用体内和体外方法来测试成骨细胞 ETAR 的 ET-1 激活在骨生长和重塑中的作用。