Genetics and Molecular Mechanisms Underlying Overgrowth Disorders of the Limb

肢体过度生长障碍的遗传学和分子机制

• 批准号: 9176482
• 负责人: Matthew P Harris
• 金额: $ 36.55万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-07-07 至 2021-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9176482
• 关键词: Address; Affect; Alleles; Animal Model; Apical Ectodermal Ridge; Area; Behavior; Biology; Catalytic Domain; Cells; Complex; Development; Differentiation and Growth; Digit structure; Disease; Distal; Elements; Embryo; Event; Gene Expression; Genes; Genetic; Genetic Models; Genetic Recombination; Gigantism; Growth; Growth Disorders; Hand; Health; Histopathology; Human; In Situ; Knock-in Mouse; Knowledge; Lead; Limb Development; Limb structure; Malignant Neoplasms; Mechanics; Mediating; Mesenchymal; Modality; Modeling; Molecular; Molecular Genetics; Morphology; Mus; Muscle; Mutation; Neoplasms; Nerve; Neurons; Organ; Organ Size; PIK3CA gene; Paracrine Communication; Pathway interactions; Patients; Pattern; Phenocopy; Phenotype; Phosphatidylinositols; Phosphotransferases; Physiological; Potassium Channel; Process; Regulation; Regulator Genes; Research; Role; Sensory; Signal Transduction; Somatic Mutation; Specificity; Structure; Syndrome; Testing; Time; Tissue Sample; Tissues; Transgenic Model; Work; Zebrafish; appendage; base; bone; cell type; developmental genetics; digital; exome sequencing; foot; gain of function mutation; in vivo Model; insight; malformation; mouse model; mutant; neoplastic; neurotransmission; novel; novel strategies; organ growth; organ regeneration; relating to nervous system; response; skeletal tissue; soft tissue; tissue repair

Summary The orchestration of growth and differentiation during development is essential for normal mechanical and physiological function of organs and appendages. Despite its importance, the regulation of how coordinated growth occurs such that proportion is maintained is not well understood. To gain insight into this process, we studied the congenital overgrowth disorder macrodactyly characterized by local giganticism of the digits of the hand and feet. Macrodactyly is a unique growth disorder in that the skeletal and soft tissue elements of the digits including nerve, vasculature, muscle and bone are enlarged, however organized such that larger digits form. Thus, patients with macrodactyly represent a unique biologic opportunity to explore fundamental mechanisms of how growth, size and proportion are coordinated within and between tissues. We have identified a specific somatic activating mutation in the catalytic subunit of phosphoinositide 3 kinase (PI3K), encoded by the gene PIK3CA, within affected tissue of macrodactyly patients. This mutation is also commonly found in cancer and other overgrowth disorders; thus, this mutation alone cannot explain the coordinated growth response observed in macrodactyly. How does this particular mutation lead to overgrowth that is coordinated and patterned during the development of the limbs? The restriction of overgrowth to the digits in these patients as opposed to the proximal limb, suggests a role for tissue interactions in the distal limb during development to regulate patterned growth and size. Additionally, we have identified potential modifier mutations arising in concert with PIK3CA that may be essential for PI3K regulation of overgrowth. We hypothesize that PI3K-mediated signaling coordinates growth through specific paracrine signaling from sensory neural tissues during development in a manner that is dependent on signaling between the apical ectodermal ridge (AER) and mesenchymal tissues during limb development. We propose to investigate the regulation of coordinated growth by PI3K through: 1) identification and localization of the affected cells and tissues containing mutant PIK3CA in macrodactyly patients and examination of the effect of these mutant cells on adjacent tissues; 2) use of novel zebrafish models to dissect the genetic and developmental causes of overgrowth though systematic analysis of newly identified secondary modifier mutations in regulating PIK3CA function and 3) the use of a conditional knockin mouse model of activated PIK3CA to test the sufficiency of increased PI3K signaling within specific tissues of the developing mouse limb to phenocopy macrodactyly. The proposed research will define the molecular and tissue level regulation of organ size and growth that will lead to new treatment modalities for a host of overgrowth and neoplastic conditions and yield new strategies for enhancing tissue repair and organ regeneration.

概括 开发过程中生长和分化的编排对于正常的机械和 器官和附属物的生理功能。尽管它的重要性，但对如何协调的监管 增长的发生使得维持比例尚不​​清楚。为了深入了解这一过程，我们 研究了先天性过度生长障碍，其特征是以局部巨大为特征 手和脚。宏观的是一种独特的生长障碍，因为 包括神经，脉管系统，肌肉和骨骼在内的数字，但是井井有条，以至于更大的数字 形式。因此，宏观影响的患者代表了探索基本的独特生物学机会 生长，大小和比例如何在组织之间和组织之间协调的机制。我们有 在磷酸肌醇3激酶（PI3K）的催化亚基中鉴定了特定的体细胞激活突变， 由基因PIK3CA编码，在受影响的巨型患者的组织中。这个突变通常也是 在癌症和其他过度生长的疾病中发现；因此，仅此突变无法解释协调的 在巨律中观察到的生长反应。这种特定的突变如何导致过度生长 在四肢发展过程中进行了协调和图案？限制过度生长到数字中 这些患者与近端肢体相反，这表明在远端肢体中组织相互作用的作用 开发以规范图案增长和规模。此外，我们已经确定了潜在的修饰符 与PIK3CA共同产生的突变可能对于PI3K过度生长至关重要。我们 假设PI3K介导的信号传导通过特定的旁分泌信号传导坐在 发育过程中的感觉神经组织的方式取决于顶端之间的信号 肢体发育过程中外胚层脊（AER）和间充质组织。我们建议调查 通过以下方式调节PI3K协调生长：1）受影响细胞的鉴定和定位 在巨型患者中含有突变PIK3CA的组织以及检查这些突变细胞的作用 在相邻的组织上； 2）使用新型斑马鱼模型来剖析 通过对新鉴定的二级修饰符突变的系统分析在调节PIK3CA时过度生长 功能和3）使用有条件的敲蛋白小鼠模型激活的PIK3CA测试足够的功能 在发育中的小鼠肢体的特定组织中增加了PI3K信号传导，以巨型表症。这 拟议的研究将定义器官大小和生长的分子和组织水平调节，这将导致 为新的治疗方式，以实现多种过度生长和肿瘤状况，并为 增强组织修复和器官再生。