PRRT2 frameshift mutation reduces its mRNA stability resulting loss of function in paroxysmal kinesigenic dyskinesia
PRRT2 frameshift mutation reduces its mRNA stability resulting loss of function in paroxysmal kinesigenic dyskinesia
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PRRT2 移码突变降低了其 mRNA 稳定性，导致阵发性运动源性运动障碍的功能丧失
DOI：
10.1016/j.bbrc.2019.11.025
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发表时间：
2020-02-12
影响因子：
3.1
通讯作者：
Tang, Beisha
中科院分区：
文献类型：
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作者：
Pan, Yongcheng;Liu, Qiong;Tang, Beisha
杂合移码PRRT 2突变（c.649_650InsC）已被确定为几种阵发性疾病（包括阵发性运动诱发性运动障碍（PKD））的主要致病突变。由于PKD是一种常染色体显性遗传疾病，并且由于PRRT 2的移码突变可能产生截短的蛋白质，因此仍不清楚该突变是否导致毒性功能获得或功能丧失。通过产生表达具有c.649_650InsC突变的人PRRT2的Prrt2敲入（KI）小鼠，并通过比较Prrt2 KI小鼠与敲除（KO）小鼠的表型，我们发现KI和KO小鼠均显示出相同程度的旋转杆和平衡木性能受损以及对癫痫发作诱导的相同敏感性。KI和KO小鼠均显示SNARE复合物的形成和突触囊泡的数量改变。此外，KI小鼠脑组织的蛋白质印迹法不能检测到可能由c.649_650InsC突变产生的截短的PRRT2蛋白。此外，KI小鼠中PRRT 2 mRNA的水平显著降低，重现了PKD患者中报告的PRRT 2 mRNA的降低。此外，突变体PRRT2 mRNA是不稳定的，并且显示出比野生型PRRT2 mRNA缩短的半衰期。我们的研究表明，PRRT 2移码突变通过影响其mRNA稳定性而导致功能丧失，这一机制不同于由于蛋白质功能失调或截短蛋白引起的功能获得而导致的单倍不足。(C)2019爱思唯尔公司All rights reserved.
A heterozygous frameshift PRRT2 mutation (c.649_650InsC) has been identified as the major causative mutation in several paroxysmal disorders, including paroxysmal kinesigenic dyskinesia (PKD). Since PKD is an autosomal dominant disorder and since the frameshift mutations of PRRT2 may create a truncated protein, it remains unclear whether this mutation causes toxic gain of function or loss of function. By generating Prrt2 knock-in (KI) mice that express human PRRT2 with the c.649_650InsC mutation and by comparing the phenotypes of Prrt2 KI mice with knockout (KO) mice, we find that both KI and KO mice show the same extents of impaired rotarod and balance beam performance as well as the same sensitivity to seizure induction. Both KI and KO mice show altered formation of SNARE complex and number of synaptic vesicles. In addition, western blotting of KI mouse brain tissues could not detect truncated PRRT2 protein that might be generated by the c.649_650InsC mutation. Moreover, the level of PRRT2 mRNA in KI mice is significantly decreased, recapitulating the reduction of PRRT2 mRNA reported in PKD patients. Furthermore, mutant PRRT2 mRNA is unstable and showed shortened half-life than wild-type PRRT2 mRNA. Our studies suggest that PRRT2 frameshift mutation leads to the loss of function by affecting its mRNA stability, a mechanism that is different from haploinsufficiency due to dysfunctional protein or gain of function caused by truncated protein. (C) 2019 Elsevier Inc. All rights reserved.