Institute of Medical Genetics and Applied Genomics, University of Tuebingen, Calwerstrasse 7, 72076, Tuebingen, Germany.
Centre for Rare Diseases, University of Tuebingen, 72076, Tuebingen, Germany.
Mol Brain. 2021 Mar 19;14(1):57. doi: 10.1186/s13041-020-00723-0.
Spinocerebellar ataxia type 3 (SCA3) is a rare neurodegenerative disorder resulting from an aberrant expansion of a polyglutamine stretch in the ataxin-3 protein and subsequent neuronal death. The underlying intracellular signaling pathways are currently unknown. We applied the Reverse-phase Protein MicroArray (RPMA) technology to assess the levels of 50 signaling proteins (in phosphorylated and total forms) using three in vitro and in vivo models expressing expanded ataxin-3: (i) human embryonic kidney (HEK293T) cells stably transfected with human ataxin-3 constructs, (ii) mouse embryonic fibroblasts (MEF) from SCA3 transgenic mice, and (iii) whole brains from SCA3 transgenic mice. All three models demonstrated a high degree of similarity sharing a subset of phosphorylated proteins involved in the PI3K/AKT/GSK3/mTOR pathway. Expanded ataxin-3 strongly interfered (by stimulation or suppression) with normal ataxin-3 signaling consistent with the pathogenic role of the polyglutamine expansion. In comparison with normal ataxin-3, expanded ataxin-3 caused a pro-survival stimulation of the ERK pathway along with reduced pro-apoptotic and transcriptional responses.
脊髓小脑共济失调 3 型（SCA3）是一种罕见的神经退行性疾病，由 ataxin-3 蛋白中异常扩展的多聚谷氨酰胺延伸段和随后的神经元死亡引起。目前尚不清楚其潜在的细胞内信号通路。我们应用反相蛋白微阵列（RPMA）技术，使用三种表达扩展 ataxin-3 的体外和体内模型，评估 50 种信号蛋白（磷酸化和总形式）的水平：（i）稳定转染人 ataxin-3 构建体的人胚肾（HEK293T）细胞，（ii）SCA3 转基因小鼠的小鼠胚胎成纤维细胞（MEF），和（iii）SCA3 转基因小鼠的全脑。所有三种模型都表现出高度的相似性，共享一组参与 PI3K/AKT/GSK3/mTOR 途径的磷酸化蛋白。扩展的 ataxin-3 强烈干扰（通过刺激或抑制）正常的 ataxin-3 信号，这与多聚谷氨酰胺扩展的致病作用一致。与正常的 ataxin-3 相比，扩展的 ataxin-3 对 ERK 通路产生了促生存刺激，同时减少了促凋亡和转录反应。
