Using a Rare Disease Model to Explore the Role of FGF21 in Insulin Resistance

项目摘要/摘要 胰岛素介导的假性肢端肥大症(IMPA)是一种罕见的胰岛素抵抗综合征，与其他 胰岛素抵抗综合症，因为它会导致过度生长和身材高大。尽管有少数报告的病例发生在 在文献中，这种疾病没有分子或遗传学的解释。一例青少年的外显子组测序 患有IMPA的女性及其兄弟姐妹和父母透露，她携带两种罕见的、可能有害的变种 在成纤维细胞生长因子受体1(FGFR1R)和𝛽𝛽-Klotho(KLb)中，这两种受体形成了 成纤维细胞生长因子21(FGF21)。我们假设这些突变可以解释极端的胰岛素 在IMPA中可见抵抗、高个子和脂肪营养不良样表型。为了测试这些FGFR1的功能和 在体内，我们使用CRISPR/Cas9基因组编辑技术创建了一个转基因敲入小鼠系 这些变异并纠正了诱导多能干细胞(IPSC)系中的FGFR1和KLB突变 从患有IMPA的先证者身上分离出来。在这项研究中，我们提出了以下具体目标。在目标1中，我们 将决定IMPA小鼠(带有FGFR1/KLb突变)的代谢和生理表型是否是 FGF21信号受损的后果。在目标2中，我们将确定IMPA患者的胰岛素抵抗是否 由于脂肪细胞功能受损。在目标3中，我们将确定IMPA中脂肪肝的发病机制。 突变的小鼠。 除了形成一种功能性遗传学方法来定义一种新的胰岛素抵抗综合征外，这 四年提案概述了首席调查员#年职业发展的综合战略 学术儿科内分泌学。这一策略在逻辑上建立在首席调查员之前的研究基础上 经验和临床培训。在获得医学博士学位后，首席调查员完成了住院医师培训 普通儿科学，以及儿科内分泌学研究。该提案现在的重点是扩大他的 通过在研究转基因生物中获得额外知识和实际研究经验而获得的科学技能 一种罕见的人类胰岛素抵抗综合征的小鼠模型。将实现职业发展目标 通过David Ornitz博士的多方面指导方法(成纤维细胞生长因子和 转基因小鼠模型)和Fumihiko Urano博士(小鼠代谢测试)，动手实验室经验， 科学调查和遗传学/基因组学、生物统计学、科学交流和研究方面的培训 伦理道德。这项工作将在一个独特的培训环境中进行，该环境由以下方面的补充经验组成 华盛顿大学和圣路易斯儿童医院。圆满完成这一职业发展 获奖将导致首席研究员转变为独立的内科科学家。此外，这一点 这项工作将有助于更好地理解FGF21在人类胰岛素抵抗中所起的作用，这将 为主要研究人员申请未来R01级别的资金提供基础。

Project Summary/Abstract Insulin-mediated pseudoacromegaly (IMPA) is a rare insulin resistance syndrome that is distinct from other insulin resistance syndromes, as it leads to overgrowth and tall stature. Despite the handful of reported cases in the literature, there is no molecular or genetic explanation for this disease. Exome sequencing on an adolescent female with IMPA and her sibling and parents revealed that she carries two rare, potentially deleterious, variants in Fibroblast Growth Factor Receptor 1 (FGFR1) and 𝛽𝛽-Klotho (KLB), which form the receptor complex for Fibroblast Growth Factor 21 (FGF21). We hypothesize that these mutations explain the extreme insulin resistance, tall stature, and lipodystrophy-like phenotype seen in IMPA. To test the function of these FGFR1 and KLB variants in vivo, we used CRISPR/Cas9 genome editing to create a transgenic knock-in mouse line with these variants and corrected the FGFR1 and KLB mutations in an induced pluripotent stem cell (iPSC) line isolated from our proband with IMPA. In this study, we are proposing the following specific aims. In Aim 1, we will determine whether the metabolic and physical phenotype of IMPA mice (with mutations in Fgfr1/Klb) is a consequence of impaired FGF21 signaling. In Aim 2, we will determine if the insulin resistance seen in IMPA is due to impaired adipocyte function. In Aim 3, we will determine the mechanism of fatty liver disease in IMPA mutant mice. In addition to forming a functional genetic approach toward defining a novel insulin resistance syndrome, this four-year proposal outlines a comprehensive strategy for the principal investigator's career development in academic pediatric endocrinology. This strategy logically builds on the principal investigator's previous research experience and clinical training. After obtaining his MD, the principal investigator completed his residency training in general pediatrics, and fellowship in pediatric endocrinology. This proposal now focuses on expanding his scientific skills by attaining additional knowledge and practical research experience in studying a transgenic mouse model of a rare human insulin resistance syndrome. The career development goals will be achieved through a multi-faceted approach involving mentoring by Dr. David Ornitz (fibroblast growth factors and transgenic mouse models) and Dr. Fumihiko Urano (metabolic testing in mice), hands-on laboratory experience, scientific investigation, and training in genetics/genomics, biostatistics, scientific communication, and research ethics. This work will take place in a unique training environment comprised of complementary experiences at Washington University and St. Louis Children's Hospital. Successful completion of this career development award will result in the principal investigator's transition to an independent physician-scientist. Additionally, this work will contribute to a better understanding of the role that FGF21 plays in human insulin resistance, which will provide the foundation for the principal investigator to apply for future R01-level funding.