The Role of FBN1 in mammalian energy balance

描述（由申请人提供）：该提案描述了为期五年的指导实验室培训经历，旨在引导临床相关基础科学的独立学术生涯。申请人拥有医学博士和博士学位，正在完成医学遗传学的专业培训，以获得董事会认证。职业发展计划包括有指导的研究训练，其中包括学习新的研究技术和概念，辅以教学训练、研讨会、赠款写作讲习班、实验室会议、期刊俱乐部、在国家/国际会议上的发言、咨询委员会和与导师的定期会议。研究环境提供了最好的智力环境和技术，并为申请人提供了学习脂肪和线粒体生物学以及患者导向研究的指导机会。该研究试图将患有导致极度消瘦的罕见遗传疾病的患者提供的见解带入实验室，以揭示产生这种表型的机制。在这一点上，它是一个从床边到台架的基础科学的例子，有可能为肥胖、代谢综合征和糖尿病等更常见的疾病提供信息。所有患者都被鉴定为FBN1远端杂合截断突变，该突变编码纤颤蛋白-1，一种与马凡氏综合征相关的细胞外基质蛋白。患者的热量摄入远高于正常水平，并且没有过度运动或脂肪漏的证据，这表明线粒体解偶联增强是能量损失的一种手段。FBN1在白色脂肪组织中高表达，体外和体内操纵脂肪细胞后其表达发生强烈变化。与WT相比，来自c端截断突变型成纤维细胞的脂肪组织显示出与关闭白色脂肪程序而偏向棕色/米色脂肪程序一致的基因表达谱，包括UCP1的大量增加，UCP1是解偶联呼吸的标志。这为可能导致极端薄化的持续能量损失提供了一个合理的途径。该研究将确定c端截断突变的成纤维细胞和衍生脂肪细胞的线粒体表型，并将测试受影响患者预测的代谢率增加。这种表型的机制基础将通过定义突变等位基因的mRNA和蛋白质产物来探索，然后确定缺失多肽的单倍不足或突变蛋白的显性阴性/新形态效应是造成这种效应的原因。这项研究将对白色和米色脂肪组织的发育以及相关的线粒体生物学有更广泛的了解。这可能具有临床意义，并有可能提供新的治疗靶点，以对抗肥胖、代谢综合征和其他与能量过剩相关的高度普遍的合并症。这项研究将在一个致力于培养申请人作为独立科学家进一步从事这项研究的环境中进行。

DESCRIPTION (provided by applicant): The proposal describes a five-year mentored laboratory training experience designed to lead to an independent academic career in clinically-relevant basic science. The applicant holds M.D. and Ph.D. degrees, and is completing specialty training, leading to board certification, in Medical Genetics. The career development plan includes mentored research training which will comprise learning new research techniques and concepts supplemented by didactic training, seminars, grant-writing workshops, lab meetings, journal clubs, presentations at national/international meetings, an advisory committee and regular meetings with the mentors. The research environment provides the best intellectual environment and technology available and gives the applicant the opportunity to be guided in learning adipose and mitochondrial biology and patient oriented research. The research seeks to take insights provided by patients suffering from a rare genetic disease that leads to extreme thinness into the laboratory in order to unravel the mechanism by which such a phenotype is produced. In that, it is an example of bedside- to-bench basic science that has the potential to inform far commoner diseases such as obesity, metabolic syndrome and diabetes. The patients have all been identified to have distal, heterozygous, truncating mutations in FBN1, which encodes for Fibrillin-1, an extracellular matrix protein that is associated with Marfan syndrome. The patients have much greater than normal caloric intake, and there is no evidence of excessive physical activity or steatorrhea, suggesting enhanced mitochondrial uncoupling as a means for loss of energy. FBN1 is expressed highly in white adipose tissue and its expression changes robustly upon manipulation of fat cells in vitro and in vivo. Adipose tissue derived from C-terminal truncation mutant fibroblasts, compared with WT, displays a gene expression profile consistent with turning off of the white adipose program in favor of the brown/beige adipose program, including a large increase in UCP1, which is a marker of uncoupled respiration. This provides a plausible avenue for unabated energy loss potentially leading to extreme thinness. The proposed research will define the mitochondrial phenotype of C-terminal truncation mutant fibroblasts and derived adipocytes, and will test the predicted increased metabolic rate in affected patients. The mechanistic basis for this phenotype will then be explored by defining the mRNA and protein product of the mutant allele followed by establishing whether haploinsufficiency of the missing polypeptide or dominant negative/neomorphic effect of the mutant protein is responsible for the effect. This research will create a broader understanding of the development of white and beige adipose tissue and associated mitochondrial biology. This could have clinical implications, and has the potential to provide new therapeutic targets, against obesity, metabolic syndrome and other highly prevalent comorbidities associated with energy excess. This research will occur in an environment dedicated to training the applicant to pursue this research further as an independent scientist.