Ouro proteins are not essential to tail regression during Xenopus tropicalis metamorphosis.
Ouro proteins are not essential to tail regression during Xenopus tropicalis metamorphosis.
复制标题
DOI：
10.1111/gtc.12337
复制
发表时间：
2016-03
期刊：
影响因子：
--
通讯作者：
Yaoita Y
中科院分区：
文献类型：
--
作者：
Nakai Y;Nakajima K;Robert J;Yaoita Y
尾部退缩是无尾目动物变态过程中观察到的最显著的变化之一。热带非洲爪哇的蝌蚪尾巴是蝌蚪躯干的两倍，在三天内几乎消失。几年前，有人提出这种现象是由幼虫皮肤特异性抗原Ouro蛋白的免疫排斥反应引起的。我们使用TALEN方法产生了Ouro基因敲除的蝌蚪，以重新检查这种免疫排斥模型。在尾部皮肤中，ouro1和ouro2基因敲除的蝌蚪都表达了从目标Ouro基因转录的非常低水平的mRNA，目标基因编码的Ouro蛋白的水平是无法检测到的，而另一种Ouro蛋白的水平是几乎检测不到的。此外，通过对Foxn1基因的修饰，获得了先天性无性蛙。流式细胞仪分析显示，突变蛙缺乏脾CD8+T细胞，而CD8+T细胞在细胞毒反应中起主要作用。此外，T细胞依赖的同种异体皮肤移植排斥反应在突变青蛙中显著受损。在变态的高峰期，没有一只敲除的蝌蚪在尾巴缩短过程中表现出明显的延迟，这表明Ouro蛋白对尾部回归不是必不可少的，至少在热带爪哇是这样的，并反对免疫排斥模型。
Tail regression is one of the most prominent transformations observed during anuran metamorphosis. A tadpole tail that is twice as long as the tadpole trunk nearly disappears within three days in Xenopus tropicalis. Several years ago, it was proposed that this phenomenon is driven by an immunological rejection of larval-skin-specific antigens, Ouro proteins. We generated ouro-knockout tadpoles using the TALEN method to reexamine this immunological rejection model. Both the ouro1- and ouro2-knockout tadpoles expressed a very low level of mRNA transcribed from a targeted ouro gene, an undetectable level of Ouro protein encoded by a target gene and a scarcely detectable level of the other Ouro protein from the untargeted ouro gene in tail skin. Furthermore, congenital athymic frogs were produced by Foxn1 gene modification. Flow cytometry analysis revealed that mutant frogs lacked splenic CD8+ T cells, which play a major role in cytotoxic reaction. Furthermore, T cell-dependent skin allograft rejection was dramatically impaired in mutant frogs. None of the knockout tadpoles showed any significant delay in the process of tail shortening during the climax of metamorphosis, which demonstrates that Ouro proteins are not essential to tail regression at least in Xenopus tropicalis and argues against the immunological rejection model.