PRRT2 frameshift mutation reduces its mRNA stability resulting loss of function in paroxysmal kinesigenic dyskinesia

• Type of Material: Article
• Authors: Yongcheng Pan, Central South University; Qiong Liu, Central South University; Jennifer Zhang, Emory University; Yang Yang, Central South University; Yun Tian, Central South University; Junsheng Zeng, Central South University; Peng Yin, Jinan University; Lin Mei, Case Western Reserve University; Wen-cheng Xiong, Case Western Reserve University; Xiao-Jiang Li, Emory University; Shihua Li, Emory University; Beisha Tang, Central South University
• Language: English
• Date: 2020-02-12
• Publisher: ACADEMIC PRESS INC ELSEVIER SCIENCE
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: 2019
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.bbrc.2019.11.025
• Title of Journal or Parent Work: BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
• Volume: 522
• Issue: 3
• Start Page: 553
• End Page: 559
• Grant/Funding Information: This work was supported by the National Natural Science Foundation of China (81130021, 81701281, 81501182) and the National Institutes of Health (grant NS036232).
• Keywords: Biophysics; Decreased mRNA stability; Biochemistry & Molecular Biology; Truncated protein; Loss of function; Science & Technology; GENE; Frameshift mutation; Prrt2 KI mice; Life Sciences & Biomedicine
• Research Categories: Biology, Molecular; Biology, Genetics; Biophysics, General

Abstract

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.