Department of Pediatric Neurology, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China.
Department of Hand Surgery, The First Hospital of Jilin University, Changchun, Jilin 130021, P.R. China.
Oncol Rep. 2020 Jul;44(1):156-164. doi: 10.3892/or.2020.7592. Epub 2020 Apr 22.
An aberrant elongated tract of glutamine residues (polyQ) in proteins induces multiple diseases treated in the clinic. In our previous study of progressive myoclonic epilepsy (PME), using whole‑exome sequencing, a mutant Cav2.1 protein with an aberrant elongated polyQ tract was identified in PME patients. To investigate the molecular mechanism and cell biology of this aberrant elongated polyQ tract, wild‑type Cav2.1 with 13 polyQ repeats (Cav2.1 wt‑Q13) and mutant‑type Cav2.1 with 26 polyQ repeats (Cav2.1 mt‑Q26) were prepared and introduced into human SH‑SY5Y neuroblastoma cells. Using a WST‑1 assay, it was revealed that Cav2.1 mt‑Q26 markedly suppressed the proliferation of the SH‑SY5Y cells, a result not observed for the Cav2.1 wt‑Q13‑transfected cells. It was also revealed that Cav2.1 mt and its truncated molecules suppressed cell proliferation by inducing apoptosis rather than arresting the cell cycle. Further investigations indicated a nuclear translocation phenomenon associated with the Cav2.1 mt molecules. Mechanistically, it was revealed that the Cav2.1 mt molecules activated the Bcl‑2/Bax, caspase‑3 and poly ADP‑ribose polymerase (PARP) apoptotic pathways. The present study may provide new insights for interpreting the pathogenesis of PME and the relationship among polyQ, CACNA1A gene mutations and PME.
在蛋白质中，异常延长的谷氨酰胺残基（多聚谷氨酰胺）会引发多种临床上治疗的疾病。在我们之前对进行性肌阵挛性癫痫（PME）的研究中，通过全外显子组测序，在 PME 患者中鉴定出具有异常延长的多聚谷氨酰胺结构域的突变 Cav2.1 蛋白。为了研究这种异常延长的多聚谷氨酰胺结构域的分子机制和细胞生物学特性，我们制备了野生型 Cav2.1 蛋白（含有 13 个多聚谷氨酰胺重复序列，Cav2.1wt-Q13）和突变型 Cav2.1 蛋白（含有 26 个多聚谷氨酰胺重复序列，Cav2.1mt-Q26），并将其引入人 SH-SY5Y 神经母细胞瘤细胞中。使用 WST-1 测定法，结果表明 Cav2.1mt-Q26 显著抑制了 SH-SY5Y 细胞的增殖，而 Cav2.1wt-Q13 转染的细胞则没有观察到这种情况。结果还表明，Cav2.1mt 及其截短分子通过诱导细胞凋亡而不是阻止细胞周期来抑制细胞增殖。进一步的研究表明，Cav2.1mt 分子存在核转位现象。从机制上讲，结果表明 Cav2.1mt 分子激活了 Bcl-2/Bax、caspase-3 和多聚 ADP-核糖聚合酶（PARP）凋亡途径。本研究可能为解释 PME 的发病机制以及多聚谷氨酰胺、CACNA1A 基因突变与 PME 之间的关系提供新的见解。
