Regeneration of Xenopus laevis spinal cord requires Sox2/3 expressing cells.
Regeneration of Xenopus laevis spinal cord requires Sox2/3 expressing cells.
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DOI：
10.1016/j.ydbio.2015.03.009
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发表时间：
2015-12-15
影响因子：
2.7
通讯作者：
Larraín J
中科院分区：
文献类型：
--
作者：
Muñoz R;Edwards-Faret G;Moreno M;Zuñiga N;Cline H;Larraín J
人类的脊髓再生效率非常低下，导致截瘫和四肢瘫痪。研究能够响应损伤而再生脊髓的模型生物可能有助于理解细胞和分子机制，从而解释为什么这一过程在人类身上失败。在这里，我们使用非洲爪蟾作为模式生物来研究脊髓修复。组织学和功能分析表明，变态前阶段的幼虫恢复了脊髓的解剖连续性，并在脊髓完全横断后恢复游泳。这些再生能力随着变态的开始而减弱。研究非洲爪蟾再生和非再生阶段的能力使其成为研究再生的独特模型系统。我们研究了 Sox2/3 表达细胞对脊髓损伤的反应及其在再生过程中的功能。我们发现表达 Sox2 和/或 Sox3 的细胞存在于再生动物的心室区，并且在非再生幼蛙中减少。使用由 Sox3 启动子驱动的绿色荧光蛋白 (GFP) 表达的溴脱氧尿苷 (BrdU) 实验和体内延时成像研究表明，Sox2/3+ 细胞响应再生阶段的损伤而快速、短暂和大量增殖。体内成像还表明，Sox2/3+ 神经祖细胞响应损伤而产生神经元。相比之下，这些细胞在非再生蛙中表现出延迟且非常有限的反应。 Sox2 敲低和显性失活形式的 Sox2 过度表达会破坏运动和解剖组织学恢复。我们还发现，在再生动物中，神经发生标记物会因损伤而增加，但在非再生动物中则不然。我们得出结论，Sox2 对于脊髓再生是必需的，并提出了一种模型，通过脊髓损伤激活 Sox2/3 表达细胞的增殖及其分化为神经元，这是一种在非再生蛙中丢失的机制。
Spinal cord regeneration is very inefficient in humans, causing paraplegia and quadriplegia. Studying model organisms that can regenerate the spinal cord in response to injury could be useful for understanding the cellular and molecular mechanisms that explain why this process fails in humans. Here, we use Xenopus laevis as a model organism to study spinal cord repair. Histological and functional analyses showed that larvae at pre-metamorphic stages restore anatomical continuity of the spinal cord and recover swimming after complete spinal cord transection. These regenerative capabilities decrease with onset of metamorphosis. The ability to study regenerative and non-regenerative stages in Xenopus laevis makes it a unique model system to study regeneration. We studied the response of Sox2/3 expressing cells to spinal cord injury and their function in the regenerative process. We found that cells expressing Sox2 and/or Sox3 are present in the ventricular zone of regenerative animals and decrease in non-regenerative froglets. Bromodeoxyuridine (BrdU) experiments and in vivo time-lapse imaging studies using green fluorescent protein (GFP) expression driven by the Sox3 promoter showed a rapid, transient and massive proliferation of Sox2/3+ cells in response to injury in the regenerative stages. The in vivo imaging also demonstrated that Sox2/3+ neural progenitor cells generate neurons in response to injury. In contrast, these cells showed a delayed and very limited response in non-regenerative froglets. Sox2 knockdown and overexpression of a dominant negative form of Sox2 disrupts locomotor and anatomical-histological recovery. We also found that neurogenesis markers increase in response to injury in regenerative but not in non-regenerative animals. We conclude that Sox2 is necessary for spinal cord regeneration and suggest a model whereby spinal cord injury activates proliferation of Sox2/3 expressing cells and their differentiation into neurons, a mechanism that is lost in non-regenerative froglets.