PRRT2 deficiency induces paroxysmal kinesigenic dyskinesia by regulating synaptic transmission in cerebellum

Guangming Tan ,Ze-Qiang Zhang,Yang Li,Yuan-Yuan Liu,Lu Wang,Kui Li,Renchao Chen ,Mingyue Wu ,Xuewen Cheng ,Yousheng Shu ,Dan Li,Juanjuan Long ,Chunlei Yu ,Kenji Sakimura,Jiwei Liu ,Hongfu Li ,Qi Shen,Lujian Liao ,Lixi Li ,Zhipeng Yang ,Luping Yin ,Zhi‐Ying Wu ,Zhi‐Qi Xiong

doi:10.1038/cr.2017.128

Abstract

Mutations in the proline-rich transmembrane protein 2 (PRRT2) are associated with paroxysmal kinesigenic dyskinesia (PKD) and several other paroxysmal neurological diseases, but the PRRT2 function and pathogenic mechanisms remain largely obscure. Here we show that PRRT2 is a presynaptic protein that interacts with components of the SNARE complex and downregulates its formation. Loss-of-function mutant mice showed PKD-like phenotypes triggered by generalized seizures, hyperthermia, or optogenetic stimulation of the cerebellum. Mutant mice with specific PRRT2 deletion in cerebellar granule cells (GCs) recapitulate the behavioral phenotypes seen in Prrt2-null mice. Furthermore, recording made in cerebellar slices showed that optogenetic stimulation of GCs results in transient elevation followed by suppression of Purkinje cell firing. The anticonvulsant drug carbamazepine used in PKD treatment also relieved PKD-like behaviors in mutant mice. Together, our findings identify PRRT2 as a novel regulator of the SNARE complex and provide a circuit mechanism underlying the PRRT2-related behaviors.

Highlights

Paroxysmal kinesigenic dyskinesia (PKD) is the most common hereditary paroxysmal movement disorder [1, 2], characterized by attacks of choreic and/or dyston-PRRT2 is an uncharacterized protein that belongs to the PRRT superfamily that contains two predicted trans-membrane domains at its C-terminus, with high homology between human and rodents [3, 4, 10]
The specificity of the antibodies was verified by western blotting with lysates from cultured mouse cortical neurons and the results indicate that the immunostained band at 65 kDa represents the endogenous PRRT2
Immunostaining assays showed that PRRT2 protein is enriched in cerebral cortex, hippocampus, substantia nigra and cerebellum, with prominent expression in neuronal processes rather than cell bodies (Figure 1C and Supplementary information, Figure S2B), resembling the expression pattern of presynaptic proteins (Figure 1D and 1E; Supplementary information, Figure S2C)

Summary

Introduction

Paroxysmal kinesigenic dyskinesia (PKD) is the most common hereditary paroxysmal movement disorder [1, 2], characterized by attacks of choreic and/or dyston-PRRT2 is an uncharacterized protein that belongs to the PRRT superfamily that contains two predicted trans-membrane domains at its C-terminus, with high homology between human and rodents [3, 4, 10]. Previous studies using a yeast two-hybrid system [11] and biochemical analyses of cultured cell lines [10, 12] have implied the presence of PRRT2 in synapses. PRRT2 was shown to interact with the fast Ca2+ sensors synaptotagmin 1/2, a protein critical for neurotransmitter release [14]. Existing data imply the possible involvement of PRRT2 in synaptic regulation, its interacting proteins and subcellular localization remain controversial. Truncated versions of PRRT2 displayed altered subcellular localization in COS7 cells [3], whereas site-directed mutagenesis of full-length PRRT2 led to an almost complete absence of the protein in cultured neurons [10]. Whether truncation mutation of the PRRT2 gene in PKD patients results in a loss or gain of function remains unclear

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Results

Conclusion