Molecular and cellular determinants of enthesopathy in X-linked hypophosphatemia

X连锁低磷血症中附着点病变的分子和细胞决定因素

• 批准号: 9314995
• 负责人: Eva S. Liu
• 金额: $ 14.18万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-08-01 至 2020-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9314995
• 关键词: Ablation; Abnormal Cell; Address; Advisory Committees; Affect; Age; Alpha Cell; Antibodies; Award; Basic Science; Biology; Birth; Blocking Antibodies; Bone Diseases; Calcitonin; Cell Differentiation process; Cell Lineage; Cells; Characteristics; Chondrocytes; Chondrogenesis; Clinical; Clinical Endocrinology; Communities; Complex; Complication; Comprehension; Data; Development; Development Plans; Dihydroxycholecalciferols; Disease; Embryo; Endopeptidases; Enthesopathies; Erinaceidae; Exhibits; Experimental Designs; Fibroblast Growth Factor; Fibrocartilages; Functional disorder; Goals; Grant; Growth; Hindlimb Suspension; Homeostasis; Hypophosphatemia; Impairment; In Situ Hybridization; Inherited; Institution; Investigation; Ions; Journals; Kidney; Knock-out; Knockout Mice; Knowledge; Laboratories; Lead; Link; Manuscripts; Mechanical Stress; Mechanics; Medicine; Mentors; Mentorship; Minerals; Modality; Modeling; Molecular; Morbidity - disease rate; Mus; Muscle strain; Musculoskeletal; Musculoskeletal Diseases; Mutation; National Research Service Awards; New England; Pain; Pathogenicity; Pathologic; Pathway interactions; Patients; Phenotype; Physicians; Play; Production; Publications; Reporting; Research; Research Personnel; Rickets; Role; Scientist; Serum; Signal Pathway; Signal Transduction; Signaling Protein; Site; Sodium; Study models; Supplementation; Tendon structure; Therapeutic Agents; Training; Transgenic Organisms; Vitamin D3 Receptor; Vocational Guidance; Work; Writing; achilles tendon; bone; bone morphogenic protein; career; career development; dentin matrix protein 1; design; experience; experimental analysis; experimental study; improved; inorganic phosphate; insight; interest; laboratory experience; mechanical force; mechanical load; meetings; mineralization; motor impairment; mouse model; novel therapeutics; patellar tendon; progenitor; programs; public health relevance; scleraxis; skeletal; skills; smoothened signaling pathway; sodium phosphate; symporter; symposium; tendon development; transcription factor

 DESCRIPTION (provided by applicant): Project Summary/Abstract X-linked hypophosphatemia (XLH) is the most common form of inheritable rickets, characterized by elevated FGF23 levels leading to low serum phosphate and impaired production of 1,25 dihydroxyvitamin D (1,25(OH)2D). Mutations in the endopeptidase PHEX are responsible for the XLH phenotype. While it is known that increases in FGF23 result from PHEX mutations, the molecular basis for this remains unknown. Pathologic mineralization of the enthesis (tendon-bone attachment site), referred to as enthesopathy, is a complication of XLH. Common sites of involvement include the Achilles and patellar entheses. Although it causes significant morbidity in patients, the molecular mechanisms responsible for the enthesopathy and impact of currently available modalities of treatment on the development of enthesopathy are poorly understood. Murine models of hypophosphatemia, including the vitamin D receptor knockout (VDR KO) and the renal type II sodium dependent phosphate co-transporter (Npt2a) KO do not have enthesopathy. In contrast, mice with hypophosphatemia and elevated serum FGF23 levels, including the Hyp mouse (murine model of XLH) and the dentin matrix protein 1 (DMP1) KO, do develop enthesopathy, suggesting FGF23 and not serum phosphate could have a pathogenic role in enthesopathy development. However, VDR KO mice do not develop rickets until 3 weeks of age, while the rickets in Npt2aKO mice reverses by 4 weeks due to increased 1,25(OH)2D levels. Since both the Hyp and DMP1 KO mice have progressive rickets from birth, the impaired skeletal mineralization may alter mechanical forces in the maturing enthesis, contributing to the development of enthesopathy in XLH and DMP1 inactivation. The studies proposed are focused on elucidating the molecular and cellular basis for this enthesopathy in a murine model of XLH (Hyp mice). Investigations proposed in Aim I will provide a molecular characterization of the abnormal cells in the entheses of Hyp mice and identify signaling pathways implicated in the development of enthesopathy. The lineage tracing studies in Aim II will identify the origin of these cells in the Hyp enthesis and the pathophysiologic basis for their aberrant differentiation. The studies proposed in Aim III will identify the relative contributions of FGF23, impaired mineralization and mechanical strain on enthesopathy development and progression. The molecular pathophysiology underlying this aberrant mineralization will also provide insight into enthesis abnormalities associated with other musculoskeletal disorders. Prior studies have focused on embryonic tendon development, thus these experiments will contribute to our understanding of normal post-natal enthesis maturation. The PI, Dr. Liu, is a physician-scientist whose long-term goal is to lead an independent basic science laboratory with a focus on musculoskeletal biology. She developed a strong interest in rare bone diseases while examining the effect of calcitonin on serum FGF23 levels in patients with XLH. She designed, executed and performed analyses for this study, which led to a first author publication in the New England Journal of Medicine. This study combined with her rigorous training in clinical endocrinology allowed Dr. Liu to recognize how clinical experiences can inform her research hypotheses. Her passion for studying the molecular pathophysiology underlying XLH led her to join the laboratory of Dr. Marie Demay, a senior investigator in skeletal biology. Dr. Liu was awarded a F32/NRSA grant to investigate how different treatment modalities, including daily 1,25(OH)2D and FGF23 blocking antibody, affect growth, mineral ion homeostasis, chondrocyte differentiation, and skeletal mineralization. A K08 award will allow Dr. Liu to take advantage of the rich mentorship available in the Harvard skeletal biology community. Her co-mentor Dr. Vicki Rosen, advisory committee, and collaborators, all renowned investigators in musculoskeletal biology, will provide her with valuable advice on experimental design and analyses, as well as career guidance. The career plan, consisting of regular meetings with mentors, course work, didactic conferences, research seminars and journal clubs is designed to enhance her research experience. Dr. Liu will develop expertise in the design, execution and interpretation of studies aimed at dissecting complex skeletal phenotypes at the molecular and cellular levels. She will refine her grant and manuscript writing skills and immerse herself in the field of skeletal and tendon biology. The carefully designed career development plan, combined with a rigorous laboratory experience will provide her with the skills necessary for her to establish her independent research program in an academic institution.

 描述（由适用提供）：项目摘要/摘要X连锁性低磷酸血症（XLH）是最常见的遗传谜语形式，其特征是FGF23水平升高，导致低血清磷酸盐和生产受损1,25二羟基维生素D（1,25（OH）2D）。内肽酶PHEX中的突变负责XLH表型。虽然众所周知，FGF23的增加是由PHEX突变引起的，但其分子基础仍然未知。 Enthesis（肌腱骨附着位点）的病理矿化（称为肠病）是XLH的并发症。参与的常见部位包括阿喀琉斯和tell骨肠。尽管它在患者中引起了显着的发病率，但对当前可用治疗方式对肠病发育的影响的分子机制和影响的影响很少。低磷酸血症的鼠模型，包括维生素D接收器基因敲除（VDR KO）和II型II型钠依赖磷酸磷酸磷酸共转运蛋白（NPT2A）KO没有肠病。相反，具有下磷酸盐和血清FGF23水平升高的小鼠，包括催眠小鼠（XLH的鼠模型）和牙本质基质蛋白1（DMP1）KO，确实会发展出肠胃疾病，这表明FGF23和非血清磷酸盐可能在Entheshepathy发育中具有致病性。但是，VDR KO小鼠直到3周龄才会出现rick鼠，而NPT2ako小鼠的rick鼠由于升高1,25（OH）2D水平而逆转4周。由于催眠和DMP1 KO小鼠从出生起就具有渐进ricket，因此骨骼矿化受损可能会改变成熟源中的机械力，从而有助于XLH和DMP1灭活中的Enthesopathy的发展。提出的研究集中于阐明在XLH的鼠模型（催眠小鼠）中，该肠病的分子和细胞基础。 AIM I提出的研究将提供催眠小鼠肠中异常细胞的分子表征，并确定肠病发育中实施的信号传导途径。 AIM II中的谱系追踪研究将在催眠中鉴定这些细胞的起源以及它们异常分化的病理生理基础。在AIM III中提出的研究将确定FGF23，矿化受损和机械应变对肠病发育和进展的相对贡献。这种异常矿化基础的分子病理生理学还将洞悉与其他肌肉骨骼疾病相关的衰减异常。先前的研究集中在胚胎肌腱发育上，因此这些实验将有助于我们对正常的产后衰减成熟的理解。 PI，Liu博士是一位身体科学家，其长期目标是领导独立的基础科学实验室，重点是肌​​肉骨骼生物学。她对稀有骨骼疾病产生了浓厚的兴趣，同时检查了降钙素对XLH患者血清FGF23水平的影响。她为这项研究设计，执行和进行了分析，这导致了《新英格兰医学杂志》上的第一篇作者出版物。这项研究结合了她在临床内分泌学上进行严格的培训，使刘博士能够认识到临床经验如何告知她的研究假设。她对研究XLH基础的分子病理生理学的热情使她加入了骨骼生物学高级研究员Marie DeMay博士的实验室。 Liu博士获得了F32/NRSA赠款，以研究不同的治疗方式，包括每日1,25（OH）2d和FGF23阻断抗体，影响生长，矿物离子稳态，软骨细胞分化和骨骼矿化。 K08奖将使Liu博士能够利用哈佛骨骼生物学社区的丰富心态。她的同事Vicki Rosen博士，咨询委员会和合作者，所有著名的肌肉骨骼生物学调查员将为她提供有关实验设计和分析以及职业指导的宝贵建议。该职业计划包括与导师，课程工作，教学会议，研究半手赛和期刊俱乐部的定期会议组成，旨在增强她的研究经验。 Liu博士将在旨在在分子和细胞水平上剖析复杂骨骼表型的研究的设计，执行和解释方面发展专业知识。她将完善自己的赠款和手稿写作技巧，并沉浸在骨骼和肌腱生物学领域。精心设计的职业发展计划，再加上严格的实验室经验，将为她提供在学术机构中建立独立研究计划所需的技能。