Why Don’t Lizards Regenerate Perfect Tails Like Salamanders?

为什么蜥蜴不能像火蜥蜴那样再生出完美的尾巴？

• 批准号: 9104474
• 负责人: Thomas Peter Lozito
• 金额: $ 28.92万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-05-01 至 2021-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9104474
• 关键词: Amaze; Ambystoma; Ambystoma mexicanum; Animal Model; Animals; Area; Calcified; Cartilage; Cell Line; Cell Proliferation; Cell Transplantation; Cells; Characteristics; Chondrocytes; Complex; Development; Dorsal; Employee Strikes; Environment; Erinaceidae; Exhibits; Female; Genetic Engineering; Goals; Healed; Human; Immunosuppression; Individual; Intervention; Intervertebral disc structure; Knowledge; Lead; Learning; Length; Lizards; Mammals; Medicine; Molecular; Natural regeneration; Neural tube; Operative Surgical Procedures; Organism; Outcome; Patients; Pattern; Pattern Formation; Periosteal Cell; Phenocopy; Population; Process; Proliferating; Regenerative Medicine; Role; Salamander; Signal Transduction; Skeletal Development; Skeleton; Spinal Cord; Stem cells; Tail; Tissue Transplantation; Tissues; Translating; Tube; Vertebral column; base; comparative; design; experience; genome editing; healing; implantation; improved; in vivo; innovation; insight; knowledge base; nerve stem cell; offspring; public health relevance; regenerative; repaired; research study; retinal rods; skeletal; skeletal regeneration; smoothened signaling pathway; stem cell population; tissue regeneration; transcriptomics; vertebra body

 DESCRIPTION (provided by applicant): Enhancing regenerative capacities is a fundamental goal in medicine. As yet, the principles of salamander regeneration to augment mammalian healing are not directly applicable. Here we propose using lizards, more closely related to mammals yet exhibiting remarkable regenerative capabilities, as a model organism in a set of studies aimed at manipulating skeletal regeneration capacities. While both salamanders and lizards regenerate their tails, the former regenerate a near-perfect copy of the original tail, whie the latter is known as an "imperfect replicate" with several key anatomical differences compared to the original tail, most striking of which concerns the regenerated tail skeleton. Our recent comparative analyses of regenerated tail development have identified 3 main differences related to (1) dorsoventral patterning signals, (2) stem cell populations, and (3) segmentation signals. During skeletal regeneration, salamanders form a cartilage rod (CR) ventral to the tail axis, whereas the regenerated lizard tail lacks dorsoventral skeletal patterning and forms a cartilage tube (CT). Our initial findings suggest that the regenerated spinal cord is responsible for cartilage patterning in both salamander and lizard tails. The salamander spinal cord produces factors that both inhibit and induce cartilage formation, while the lizard spinal cord produces cartilage inductive factors only; furthermore, they differ in their neural stem cell populations. Salamander stem cells are able to differentiate into both dorsal and ventral lineages, while lizard stem cells differentiate into ventral lineages only. Once formed, the salamander CR undergoes segmentation marked by new cartilage formed at distinct regions by populations of proliferating chondrocytes and periosteal cells. These regions are not detectable in the lizard CT, which does not segment, likely due to lack of molecular proliferative signals. We hypothesize that these differences in pattern formation and regulatory networks underlie the divergent regenerative outcomes between lizards and salamanders. Based on this comparative analysis, we hypothesize the feasibility of mechanistically based intervention to shift the "imperfectly" regenerating lizard tail to phenocopy the "perfectly" regenerating salamander tail. The Aims are: (1) Manipulate the dorsoventral signals present in regenerating salamander tails but absent in lizard tails; (2) Introduce stem cell populations found in salamander but not lizard tails; and (3) Determine and manipulate the proliferative signals in regenerating salamander tails that are absent in lizard tails. An integrated approach is proposed, incorporating transcriptomics, CRIPSR/Cas9 genome editing of lizard stem cells, molecular and cellular analyses, in vivo surgical manipulations, and delivery of cell and bioactive agents. We believe that this approach will produce the first lizard tails with skeletons exhibiting patterning and segmentation that phenocopy regenerated salamander tails. These studies will contribute towards mechanistic understanding of a vertebrate regenerative process, and may lead to improving healing in non-regenerative organisms, including humans, specifically related to skeletal development and repair.

 描述（由申请人提供）：增强再生能力是医学的一个基本目标。到目前为止，蝾螈再生的原则，以加强哺乳动物的愈合是不直接适用的。在这里，我们建议使用蜥蜴，更密切相关的哺乳动物，但表现出显着的再生能力，作为一个模式生物的一组研究，旨在操纵骨骼再生能力。虽然蝾螈和蜥蜴都能再生尾巴，但前者再生的是原始尾巴的近乎完美的复制品，而后者被称为“不完美复制品”，与原始尾巴相比，有几个关键的解剖学差异，其中最引人注目的是再生的尾巴骨架。我们最近对再生尾发育的比较分析已经确定了3个主要差异，这些差异与（1）背腹图案信号，（2）干细胞群和（3）分割信号有关。在骨骼再生过程中，蝾螈在尾轴的腹侧形成一个软骨杆（CR），而再生的蜥蜴尾巴缺乏背腹侧骨骼图案，形成一个软骨管（CT）。我们的初步研究结果表明，再生的脊髓是负责蝾螈和蜥蜴尾巴的软骨图案。蝾螈脊髓产生的因子既抑制又诱导软骨形成，而蜥蜴脊髓只产生软骨诱导因子;此外，它们的神经干细胞群不同。蝾螈的干细胞能够分化成背侧和腹侧两种谱系，而蜥蜴的干细胞能够分化成背侧和腹侧两种谱系。 干细胞仅分化成腹侧谱系。一旦形成，蝾螈CR经历分割，其标记为在不同区域由增殖的软骨细胞和骨膜细胞群体形成的新软骨。这些区域在蜥蜴CT中是检测不到的，其不分段，可能是由于缺乏分子增殖信号。我们推测，这些差异的模式形成和监管网络的基础上不同的再生蜥蜴和蝾螈之间的结果。基于这种比较分析，我们假设的可行性机制为基础的干预转移的“不完美的”再生蜥蜴的尾巴表型复制的“完美的”再生蝾螈的尾巴。目标是：（1）操纵再生蝾螈尾巴中存在但蜥蜴尾巴中不存在的背腹信号;（2）引入蝾螈而不是蜥蜴尾巴中发现的干细胞群;以及（3） 确定和操纵再生蝾螈尾巴的增殖信号，这在蜥蜴尾巴中是不存在的。提出了一种综合方法，将转录组学、蜥蜴干细胞的CRIPSR/Cas9基因组编辑、分子和细胞分析、体内手术操作以及细胞和生物活性剂的递送结合起来。我们相信，这种方法将产生第一个蜥蜴尾巴的骨架展示图案和分割，表型再生蝾螈尾巴。这些研究将有助于对脊椎动物再生过程的机械理解，并可能导致改善包括人类在内的非再生生物体的愈合，特别是与骨骼发育和修复有关的愈合。