Why don't lizards regenerate perfect tails like salamanders?

为什么蜥蜴不能像蝾螈那样再生出完美的尾巴？

• 批准号: 9890788
• 负责人: Thomas Peter Lozito
• 金额: $ 33万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 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/9890788
• 关键词: Amaze; Ambystoma; Ambystoma mexicanum; Anatomy; Animal Model; Animals; Area; Cartilage; Cell Line; Cell Proliferation; Cell Transplantation; Cells; Characteristics; Chondrocytes; Complex; Development; Dorsal; Environment; Erinaceidae; Exhibits; Female; Genetic Engineering; Goals; Human; Immunosuppression; Individual; Intervention; Intervertebral disc structure; Knowledge; Lead; 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; Rod; Role; Salamander; Signal Transduction; Skeletal Development; Skeleton; Spinal Cord; Tail; Tissue Transplantation; Tissues; Translating; Tube; Vertebral column; asexual; base; calcification; cartilaginous; comparative; design; engineered stem cells; experience; experimental study; genome editing; healing; implantation; improved; in vivo; information model; innovation; insight; knowledge base; nerve stem cell; offspring; public health relevance; regenerative; repaired; skeletal; skeletal regeneration; smoothened signaling pathway; stem cell differentiation; stem cell population; stem cells; 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（由适用提供）：增强再生能力是医学的基本目标。到目前为止，萨拉曼德再生以增强哺乳动物愈合的原则尚不适用。在这里，我们建议使用蜥蜴，与哺乳动物更紧密相关，但在旨在操纵骨骼再生能力的一系列研究中，作为模型生物具有显着的再生能力。尽管萨拉曼德人和蜥蜴都会再生其尾巴，但前者再生是原始尾巴的近乎完美的副本，而后者被称为“不完美的重复”，与原始尾巴相比，几种关键的解剖学差异与原始尾巴相比，大多数引人注目的尾巴涉及重生的尾巴骨架。我们最近对再生尾部发育的比较分析已经确定了与（1）背腹图案信号，（2）干细胞种群和（3）分割信号有关的3个主要差异。在骨骼再生过程中，sal豆形成了软骨杆（CR）通气，而尾轴则是重生的蜥蜴尾巴缺乏背腹骨骼图案，并形成软骨管（CT）。我们的最初发现表明，再生的脊髓负责sal和蜥蜴尾巴的软骨模式。 sal骨脊髓会产生抑制和诱导软骨形成的因素，而蜥蜴脊髓仅产生软骨感应因子。此外，它们的神经元干细胞群体有所不同。 Salamander干细胞能够分化为背侧和腹侧谱系，而蜥蜴 干细胞仅区分腹侧谱系。一旦形成，Salamander CR进行了分割，该分割以通过增殖软骨细胞和骨膜细胞种群在不同区域形成的新软骨标记。这些区域在蜥蜴CT中无法检测到，该区域可能由于缺乏分子增殖信号而无法分割。我们假设这些模式形成和调节网络的差异是蜥蜴和萨拉曼德人之间不同再生结果的基础。基于这种比较分析，我们假设基于机械的干预措施将“不完美”再生蜥蜴尾巴转移到表态的可行性“完全”再生sallamander尾巴。目的是：（1）操纵在再生sal尾中存在的背腹信号，但在蜥蜴尾巴中不存在； （2）引入sal中发现的干细胞群体，而不是蜥蜴尾巴； （3） 在蜥蜴尾部没有的再生sal尾尾中确定并操纵增生剂信号。提出了一种综合方法，并结合了转录组学，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。我们认为，这种方法将产生第一个蜥蜴尾巴，其骨骼表现出图案和分割，将表现为再生Salamander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的愈合，特别是与骨骼发育和修复有关。