Spinocerebellar ataxia type 14 caused by a nonsense mutation in the PRKCG gene
Spinocerebellar ataxia type 14 caused by a nonsense mutation in the PRKCG gene
复制标题
DOI：
10.1016/j.mcn.2019.05.005
复制
发表时间：
2019-07-01
影响因子：
3.5
通讯作者：
Sakai, Norio
中科院分区：
文献类型：
--
作者：
Shirafuji, Toshihiko;Shimazaki, Haruo;Sakai, Norio
脊髓小脑性共济失调14型（SCA 14）是一种常染色体显性遗传性神经退行性疾病，其特征是小脑性共济失调伴肌阵挛、肌张力障碍、痉挛和强直。虽然在SCA 14家族中编码蛋白激酶C γ（PKC γ）的蛋白激酶C γ（PRKCG）基因中已发现错义突变和缺失突变，但无义突变尚未报道。SCA 14的病理机制仍然知之甚少。然而，SCA 14的病理机制报道为功能获得机制和功能丧失机制，而不是显性负性机制。我们确定了PRKCG的c.226C > T突变，通过全外显子组测序，该突变导致患有认知和听力障碍的小脑萎缩患者的PKC γ中的p.R76X。为了探讨我们的病例的病理机制，我们研究了聚集形成，细胞死亡和PKC抑制作用，分别通过共聚焦显微镜，蛋白质印迹切割caspase 3和pSer PKC motif抗体。PKC gamma（R76 X）-GFP具有与野生型（WT）PKC gamma-GFP相同的聚集。PKC γ（R76 X）-GFP比单独的GFP更抑制PKC磷酸化活性。与WT-PKC γ-GFP和GFP相比，它还诱导了COS 7和SH-SY 5 Y细胞的更多凋亡。我们首次报道了SCA 14例PKC γ中p.R76X的患者，他们患有小脑萎缩伴认知和听力障碍。我们的研究结果表明，由于截短肽产生的p.R76X的显性负性机制可能是至少部分负责小脑萎缩。
Spinocerebellar ataxia type 14 (SCA14) is an autosomal dominant neurodegenerative disorder characterized by cerebellar ataxia with myoclonus, dystonia, spasticity, and rigidity. Although missense mutations and a deletion mutation have been found in the protein kinase C gamma (PRKCG) gene encoding protein kinase C gamma (PKC gamma) in SCA14 families, a nonsense mutation has not been reported. The patho-mechanisms underlying SCA14 remain poorly understood. However, gain-of-function mechanisms and loss-of-function mechanisms, but not dominant negative mechanisms, were reported the patho-mechanism of SCA14. We identified the c.226C > T mutation of PRKCG, which caused the p.R76X in PKC gamma by whole-exome sequencing in patients presenting cerebellar atrophy with cognitive and hearing impairment. To investigate the patho-mechanism of our case, we studied aggregation formation, cell death, and PKC inhibitory effect by confocal microscopy, western blotting with cleaved caspase 3, and pSer PKC motif antibodies, respectively.PKC gamma(R76X)-GFP have aggregations the same as wild-type (WT) PKC gamma-GFP. The PKC gamma(R76X)-GFP inhibited PKC phosphorylation activity more than GFP alone. It also induced more apoptosis in COS7 and SH-SY5Y cells compared to WT-PKC gamma-GFP and GFP.We first reported SCA14 patients with p.R76X in PKC gamma who have cerebellar atrophy with cognitive and hearing impairment. Our results suggest that a dominant negative mechanism due to truncated peptides produced by p.R76X may be at least partially responsible for the cerebellar atrophy.