FGF2 Isoforms in Bone and Phosphate Homeostasis

骨和磷酸盐稳态中的 FGF2 同工型

• 批准号: 8735135
• 负责人: Marja Marie Hurley
• 金额: $ 34.32万
• 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/8735135
• 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

DESCRIPTION (provided by applicant): 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.

描述(申请人提供)：成纤维细胞生长因子23(FGF23)是与异常骨矿化和肾脏磷酸盐消耗(PI)相关的人类病理疾病的主要磷酸盐调节因子。然而，FGF23产生的调控因子、FGF23诱导的磷浪费和缺陷矿化的信号通路(S)还不完全清楚。我们的研究支持了成纤维细胞生长因子2(FGF2)的核异构体在FGF23的产生和生物学功能中的重要作用。使用在成骨细胞系细胞(HMWTg)中表达HMW亚型的新的小鼠模型和选择性缺失HMW亚型(HMWKO)的小鼠，我们证明HMWTg小鼠的血清和骨骼中的FGF23增加，侏儒症，骨密度(BMD)降低，骨软化，低磷，以及骨骼和肾脏中异常的FGF23/FGFReceptor/klotho/MAPK和Wnt信号转导。初步数据显示，去除HMWFGF2亚型可增加小鼠的骨密度，增加血磷，显著降低FGF23基因的表达。我们还观察到HMWFGF2在成骨细胞/骨细胞中的表达增加，这是一种X连锁低磷血症(XLH)的小鼠模型。我们也有令人兴奋的初步数据，HMW亚型在一名XLH患者的B淋巴细胞中过表达，支持这些研究的临床相关性。我们的中心假设是，HMWFGF2：I)通过增加骨骼中FGF23的生成，在肾脏的PI动态平衡中发挥重要作用。Ii)通过FGF23依赖和独立作用调节骨基质矿化。(Iii)造成Hyp小鼠体内PI浪费和基质矿化缺陷。目的1确定HMWFGF2亚型在HMW转基因小鼠肾脏PI动态平衡中的作用：我们的工作假设是HMWFGF2亚型增加了骨骼中FGF23的产生，内分泌FGF23介导了肾脏FGFR/Klotho/MAPK信号的异常，从而导致PI耗竭。目的2研究HMWFGF2异构体/FGF23/FGFR和Wnt信号在成骨细胞分化和矿化中的作用。将测定阻断FGF23、FGFR、MAPK/ERK和硬化素对HMWTg小鼠骨形成的影响。目的3检测HMWFGF2基因敲除对PI和骨稳态的功能影响，以及HMWFGF2基因敲除是否在Hyp小鼠异常的PI浪费和基质矿化缺陷中起重要作用。我们的工作假设是，HMWFGF2亚型介导了异常的PI动态平衡和缺陷的骨矿化。与野生型相比，HMWFGF2缺失的HMW-/-小鼠和Hyp小鼠的磷酸盐稳态、骨骼和肾脏表型将检验这一假说。我们还将评估这些小鼠的成纤维细胞生长因子/成纤维细胞生长因子受体及其下游信号通路。这项研究将极大地提高我们对HMWFGF2亚型在PI稳态和基质矿化中的作用的理解，并可能为调节这些过程在人类磷酸盐消耗障碍中的机制提供新的和基本的见解。