Activity-dependent cleavage of dyskinesia-related proline-rich transmembrane protein 2 (PRRT2) by calpain in mouse primary cortical neurons
Activity-dependent cleavage of dyskinesia-related proline-rich transmembrane protein 2 (PRRT2) by calpain in mouse primary cortical neurons
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DOI：
10.1096/fj.201902148r
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发表时间：
2020-01-01
期刊：
影响因子：
4.8
通讯作者：
Iwata, Nobuhisa
中科院分区：
文献类型：
--
作者：
Hatta, Daisuke;Shirotani, Keiro;Iwata, Nobuhisa
PRRT 2（富含脯氨酸的跨膜蛋白2）的突变引起几种神经障碍，以阵发性运动诱发性运动障碍（PKD）为代表，其特征在于由突然的随意运动触发的不随意运动的发作。据报道，PRRT 2抑制神经元兴奋，但尚不清楚PRRT 2的功能是如何在神经元兴奋过程中调节的。我们发现PRRT 2被钙激活的半胱氨酸蛋白酶calpain以神经活性依赖的方式加工成12 kDa的羧基末端片段（12 K-CTF），主要通过NMDA受体或电压门控钙通道。此外，我们阐明了12 K-CTF是通过Q220和S244处的连续裂解产生的。未检测到PRRT 2的氨基末端片段（NTF），其对应于PKD相关的截短突变体，可能是由于在多个位置处的快速切割。鉴于12 K-CTF缺乏大部分富含脯氨酸的结构域，这种切割可能参与神经元兴奋的活性依赖性增强，可能是通过PRRT 2功能的短暂收缩实现的。因此，PRRT 2可能作为神经元兴奋的缓冲器，PKD患者缺乏这种功能可能会导致其运动回路中的神经元过度兴奋。
Mutations of PRRT2 (proline-rich transmembrane protein 2) cause several neurological disorders, represented by paroxysmal kinesigenic dyskinesia (PKD), which is characterized by attacks of involuntary movements triggered by sudden voluntary movements. PRRT2 is reported to suppress neuronal excitation, but it is unclear how the function of PRRT2 is modulated during neuronal excitation. We found that PRRT2 is processed to a 12 kDa carboxy-terminal fragment (12K-CTF) by calpain, a calcium-activated cysteine protease, in a neuronal activity-dependent manner, predominantly via NMDA receptors or voltage-gated calcium channels. Furthermore, we clarified that 12K-CTF is generated by sequential cleavages at Q220 and S244. The amino-terminal fragment (NTF) of PRRT2, which corresponds to PKD-related truncated mutants, is not detected, probably due to rapid cleavage at multiple positions. Given that 12K-CTF lacks most of the proline-rich domain, this cleavage might be involved in the activity-dependent enhancement of neuronal excitation perhaps through transient retraction of PRRT2's function. Therefore, PRRT2 might serve as a buffer for neuronal excitation, and lack of this function in PKD patients might cause neuronal hyperexcitability in their motor circuits.