FGF2 Isoforms in Bone and Phosphate Homeostasis

骨和磷酸盐稳态中的 FGF2 同工型

• 批准号: 8628923
• 负责人: Marja Marie Hurley
• 金额: $ 33.26万
• 依托单位: UNIVERSITY OF CONNECTICUT SCH OF MED/DNT
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-09-17 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8628923
• 关键词: Ablation; B-Lymphocytes; Biochemical Markers; Blocking Antibodies; Bone Density; Bone Matrix; Calcium; Cell Lineage; Conditioned Culture Media; Data; Defect; Diphosphates; Disease; Dwarfism; Endocrine; Enzymes; Etiology; FGF2 gene; Familial hypophosphatemic bone disease; Fibroblast Growth Factor; Fibroblast Growth Factor 2; Fibroblast Growth Factor Receptors; Gene Expression; Genes; Homeostasis; Human; Hydrolysis; Hypophosphatemia; In Vitro; Kidney; Knock-out; MAP Kinase Gene; MAPK3 gene; Mediating; Messenger RNA; Metabolism; Minerals; Mixed Function Oxygenases; Modeling; Molecular Weight; Mus; Nuclear; Osteoblasts; Osteocytes; Osteogenesis; Osteomalacia; Pathologic; Patients; Phenotype; Physiologic calcification; Physiological; Play; Process; Production; Protein Isoforms; Rickets; Role; Serum; Signal Pathway; Signal Transduction; Testing; Tissues; Transgenic Mice; Urine; Work; bone; bone turnover; clinically relevant; fibroblast growth factor 23; in vivo; inhibitor/antagonist; inorganic phosphate; insight; interest; mRNA Expression; mineralization; mouse model; novel; osteoblast differentiation; overexpression; protein expression; public health relevance; skeletal; sodium-phosphate cotransporter proteins; symporter; wasting

Project Summary Fibroblast Growth Factor 23 (FGF23) is the major phosphate regulator in human pathologic disorders associated with abnormal bone mineralization and renal phosphate wasting (Pi). However the regulators of FGF23 production, the signal pathway(s) for FGF23 induced Pi wasting and defective mineralization are not fully understood. Our studies support an important role for the nuclear isoforms of Fibroblast Growth Factor 2 (FGF2) in FGF23 production and biologic function. Using novel mouse models expressing HMW isoforms in osteoblast lineage cells (HMWTg) mice, and mice with selective deletion of the HMW isoforms (HMWKO) mice we demonstrate that HMWTg mice have increased FGF23 in serum and bone, dwarfism, decreased bone mineral density (BMD), osteomalacia, hypophosphatemia, and abnormal FGF23/FGFReceptor/ klotho/MAPK and Wnt signaling in bone and kidney. Preliminary data shows that ablation of the HMWFGF2 isoforms increased BMD, increased serum phosphate and significantly reduced FGF23 mRNA in mice. We also observed increased expression of nuclear HMWFGF2 in osteoblasts/osteocytes in Hyp mice, a murine model of X-linked hypophosphatemic rickets (XLH). We also have exciting preliminary data that HMW isoforms are overexpressed in B-lymphocytes from a patient with XLH supporting clinical relevance of these studies. Our Central Hypotheses are that HMWFGF2: i) plays an important role in Pi homeostasis in kidney by increasing FGF23 production in bone. ii) regulates bone matrix mineralization via FGF23 dependent and independent effects. iii) contributes to Pi wasting and defective matrix mineralization in Hyp mice. Aim 1 will determine the role of HMWFGF2 isoforms in Pi homeostasis in the kidney of HMW transgenic mice: Our working hypothesis is that HMWFGF2 isoforms increase FGF23 production in bone and that endocrine FGF23 mediates abnormal FGFR/klotho/MAPK signaling in kidney that leads to Pi wasting. Aim 2 will assess the role of HMWFGF2 isoforms/FGF23/FGFR and Wnt signaling in osteoblast differentiation and mineralization. Effects of blockade of FGF23, FGFR, MAPK/ERK and sclerostin on bone formation in HMWTg mice will be determined. Aim 3 will examine functional effects of knockout of HMWFGF2 on Pi and bone homeostasis and whether HMWFGF2 is important in the abnormal Pi wasting and matrix mineralization defect in Hyp mice. Our working hypothesis is that HMWFGF2 isoforms mediate abnormal Pi homeostasis and defective bone mineralization. Examining phosphate homeostasis, the skeletal and kidney phenotypes of HMW-/- mice and Hyp mice with deletion of HMWFGF2 versus wild type littermates will test this hypothesis. We will also assess FGF/FGF Receptor and downstream signaling pathways in these mice. The proposed studies will greatly enhance our understanding of the role of HMWFGF2 isoforms in Pi homeostasis and matrix mineralization and may provide novel and fundamental insights into the mechanisms that regulate these processes in human phosphate wasting disorders.

项目概要 成纤维细胞生长因子 23 (FGF23) 是人类病理性疾病中主要的磷酸盐调节剂 与骨矿化异常和肾磷酸盐消耗（Pi）有关。然而监管机构 FGF23 的产生、FGF23 诱导的 Pi 消耗和矿化缺陷的信号通路不 完全明白了。我们的研究支持成纤维细胞生长因子 2 核亚型的重要作用 (FGF2) 在 FGF23 产生和生物功能中的作用。使用表达 HMW 同工型的新型小鼠模型 成骨细胞谱系细胞 (HMWTg) 小鼠和选择性删除 HMW 亚型的小鼠 (HMWKO) 小鼠 我们证明HMWTg小鼠血清和骨骼中FGF23增加，侏儒症，骨质减少 矿物质密度 (BMD)、骨软化、低磷血症和 FGF23/FGF 受体/klotho/MAPK 异常 骨骼和肾脏中的 Wnt 信号传导。初步数据表明 HMWFGF2 亚型的消融 增加小鼠 BMD、血清磷酸盐水平并显着降低 FGF23 mRNA。我们也 在小鼠模型 Hyp 小鼠的成骨细胞/骨细胞中观察到核 HMWFGF2 表达增加 X连锁低磷血症性佝偻病（XLH）。我们还有令人兴奋的初步数据表明 HMW 同工型 在 XLH 患者的 B 淋巴细胞中过度表达，支持这些研究的临床相关性。我们的 中心假设是 HMWFGF2：i) 通过增加肾脏的 Pi 稳态而发挥重要作用 骨骼中 FGF23 的产生。 ii) 通过 FGF23 依赖性和非依赖性调节骨基质矿化 影响。 iii) 导致 Hyp 小鼠中 Pi 消耗和基质矿化缺陷。目标 1 将确定 HMWFGF2 亚型在 HMW 转基因小鼠肾脏 Pi 稳态中的作用：我们的工作假设 HMWFGF2 亚型增加骨中 FGF23 的产生，并且内分泌 FGF23 介导异常 肾脏中的 FGFR/klotho/MAPK 信号传导导致 Pi 消耗。目标 2 将评估 HMWFGF2 的作用 成骨细胞分化和矿化中的亚型/FGF23/FGFR 和 Wnt 信号传导。封锁的影响 将测定 FGF23、FGFR、MAPK/ERK 和硬化素对 HMWTg 小鼠骨形成的影响。目标3将 检查 HMWFGF2 敲除对 Pi 和骨稳态的功能影响以及 HMWFGF2 是否 在 Hyp 小鼠的异常 Pi 消耗和基质矿化缺陷中起重要作用。我们的工作假设是 HMWFGF2 异构体介导异常的 Pi 稳态和骨矿化缺陷。正在检查 磷酸盐稳态，HMW-/- 小鼠和 Hyp 小鼠的骨骼和肾脏表型 HMWFGF2 与野生型同窝小鼠的比较将检验这一假设。我们还将评估 FGF/FGF 受体和 这些小鼠的下游信号通路。拟议的研究将极大地增强我们对 HMWFGF2 亚型在 Pi 稳态和基质矿化中的作用，并可能提供新的和 对调节人类磷酸盐浪费过程的机制的基本见解 失调。