A gain-of-function mutation in the acid-sensing ion channel 2a induces marked cerebellar maldevelopment in rats.
A gain-of-function mutation in the acid-sensing ion channel 2a induces marked cerebellar maldevelopment in rats.
复制标题
酸敏感离子通道 2a 中的功能获得性突变可诱导大鼠显着的小脑发育不良。
DOI：
10.1016/j.bbrc.2022.04.030
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发表时间：
2022
期刊：
影响因子：
--
通讯作者：
Ugawa S.
中科院分区：
文献类型：
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作者：
Shibata Y;Kumamoto N;Sakuma E;Ishida Y;Ueda T;Shimada S;Ugawa S.
c的退化素机械门控通道（DEGs）中特定的氨基酸取代。elegans将这些通道转化为组成型活性突变体，诱导表达deg的神经元变性。酸感应离子通道-2a （ASIC2a）是一种主要表达于中枢神经元的质子门控阳离子通道，是DEG的哺乳动物同源基因，一旦将与DEG突变体相同的突变引入其基因中，它可以保持不关闭的细胞毒性。本研究表明，在ASIC2a内在启动子的控制下，表达ASIC2a- g430f （ASIC2aG430F）的杂合转基因（Tg）大鼠表现出明显的小脑发育不良和轻度全脑萎缩。ASIC2a是功能获得突变体中最活跃的形式。Tg大鼠体型小，出现早发性共济失调步态，这一点通过旋转棒和足迹测试得到了证明。Tg出生后的大脑总体大体解剖正常，但随着年龄的增长，脑容量，特别是小脑容量逐渐减少。成年Tg脑组织组织学检查显示，小脑浦肯野细胞和颗粒细胞密度明显降低，而其他脑区细胞结构无明显改变。RT-PCR和免疫印迹分析表明，asic2ag430f转录本和蛋白在新生儿Tg的小脑变形变得明显之前就已经存在于大脑的各个区域。这些结果表明，根据野生型（WT） ASIC2a基因表达的时空模式，asic2ag430f通道可诱导同时表达ASIC2aG430Fand ASIC2a通道的Tg脑神经元致死性变性。
Specific amino acid substitutions in degenerin mechano-gated channels (DEGs) ofC. elegansconvert these channels into constitutively active mutants that induce the degeneration of neurons where DEGs are expressed. Acid-sensing ion channel-2a (ASIC2a), a proton-gated cation channel predominantly expressed in central neurons, is a mammalian ortholog of DEGs, and it can remain unclosed to be cytotoxic once the same mutations as the DEG mutants are introduced into its gene. Here we show that heterozygous transgenic (Tg) rats expressing ASIC2a-G430F (ASIC2aG430F), the most active form of the gain-of-function mutants, under the control of the intrinsic ASIC2a promoter exhibited marked cerebellar maldevelopment with mild whole-brain atrophy. The Tg rats were small and developed an early-onset ataxic gait, as evidenced by rotarod and footprint tests. The overall gross-anatomy of the Tg brain was normal just after birth, but a reduction in brain volume, especially cerebellar volume, gradually emerged with age. Histological examination of the adult Tg brain revealed that the cell-densities of cerebellar Purkinje and granule cells were markedly reduced, while the cytoarchitecture of other brain regions was not significantly altered. RT-PCR and immunoblot analyses demonstrated that ASIC2aG430Ftranscripts and proteins were already present in various regions of the neonatal Tg brain before the deforming cerebellum became apparent. These results suggest that, according to the spatiotemporal pattern of the wild-type (WT) ASIC2a gene expression, the ASIC2aG430Fchannel induced lethal degeneration in Tg brain neurons expressing both ASIC2aG430Fand ASIC2a channels.