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.

总结 在发育过程中，生长和分化的协调对于正常的机械和生物学功能是必不可少的。 器官和附属物的生理功能。尽管其重要性，如何协调的监管 生长发生的方式是保持比例，这一点还没有得到很好的理解。为了深入了解这一过程，我们 研究了先天性过度生长障碍巨指症的特点是当地的手指， 手和脚。巨指（趾）畸形是一种独特的生长障碍， 包括神经、脉管系统、肌肉和骨骼的手指被增大，然而被组织成使得较大的手指 form.因此，巨指患者代表了一个独特的生物学机会，探索基本的 生长、大小和比例如何在组织内和组织间协调的机制。我们有 鉴定了磷酸肌醇3激酶（PI 3 K）催化亚基中的特异性体细胞激活突变， 由基因PIK 3CA编码，在巨指患者的受影响组织内。这种突变通常也是 在癌症和其他过度生长障碍中发现;因此，这种突变本身不能解释协调的 在巨指畸形中观察到生长反应。这种特殊的突变是如何导致 在四肢的发育过程中协调和形成模式？限制过度增长的数字， 这些患者与近端肢体相反，表明在治疗过程中远端肢体中组织相互作用的作用。 发育以调节图案化的生长和大小。此外，我们已经确定了潜在的改性剂 与PIK 3CA一致发生的突变可能是过度生长的PI 3 K调节所必需的。我们 假设PI 3 K介导的信号通过特异性旁分泌信号调节生长， 感觉神经组织在发育过程中的方式，这是依赖于顶端之间的信号传导， 外胚层嵴（AER）和间充质组织在肢体发育。我们建议调查 通过PI 3 K调节协调生长，包括：1）鉴定和定位受影响的细胞， 巨指患者中含有突变PIK 3CA的组织和这些突变细胞的作用的检查 2）使用新的斑马鱼模型来剖析遗传和发育的原因， 通过系统分析新鉴定的调节PIK 3CA的二级修饰突变的过度生长 功能和3）使用活化的PIK 3CA的条件性敲入小鼠模型来测试 在发育中的小鼠肢体的特定组织内增加PI 3 K信号传导以表型模仿巨指。的 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 新的治疗方式，为主机的过度生长和肿瘤条件，并产生新的战略， 增强组织修复和器官再生。