Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States; Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, United States.
Institute for Translational Neuroscience, University of Minnesota, Minneapolis, MN, United States; Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, United States.
Neurobiol Dis. 2018 Aug;116:93-105. doi: 10.1016/j.nbd.2018.05.002. Epub 2018 May 11.
Spinocerebellar ataxia type 1 (SCA1) is a polyglutamine (polyQ) repeat neurodegenerative disease in which a primary site of pathogenesis are cerebellar Purkinje cells. In addition to polyQ expansion of ataxin-1 protein (ATXN1), phosphorylation of ATXN1 at the serine 776 residue (ATXN1-pS776) plays a significant role in protein toxicity. Utilizing a biochemical approach, pharmacological agents and cell-based assays, including SCA1 patient iPSC-derived neurons, we examine the role of Protein Kinase A (PKA) as an effector of ATXN1-S776 phosphorylation. We further examine the implications of PKA-mediated phosphorylation at ATXN1-S776 on SCA1 through genetic manipulation of the PKA catalytic subunit Cα in Pcp2-ATXN1[82Q] mice. Here we show that pharmacologic inhibition of S776 phosphorylation in transfected cells and SCA1 patient iPSC-derived neuronal cells lead to a decrease in ATXN1. In vivo, reduction of PKA-mediated ATXN1-pS776 results in enhanced degradation of ATXN1 and improved cerebellar-dependent motor performance. These results provide evidence that PKA is a biologically important kinase for ATXN1-pS776 in cerebellar Purkinje cells.
脊髓小脑共济失调 1 型（SCA1）是一种多聚谷氨酰胺（polyQ）重复的神经退行性疾病，其发病的主要部位是小脑浦肯野细胞。除了 ATXN1 蛋白的 polyQ 扩展外，丝氨酸 776 残基（ATXN1-pS776）的 ATXN1 磷酸化在蛋白毒性中起着重要作用。利用生化方法、药理学制剂和基于细胞的测定法，包括 SCA1 患者诱导多能干细胞衍生的神经元，我们研究了蛋白激酶 A（PKA）作为 ATXN1-S776 磷酸化效应物的作用。我们通过 Pcp2-ATXN1[82Q]小鼠中 PKA 催化亚基 Cα 的遗传操作进一步研究了 PKA 介导的 ATXN1-S776 磷酸化对 SCA1 的影响。在这里，我们表明在转染细胞和 SCA1 患者诱导多能干细胞衍生的神经元细胞中，S776 磷酸化的药理学抑制导致 ATXN1 的减少。在体内，减少 PKA 介导的 ATXN1-pS776 导致 ATXN1 的降解增强和小脑依赖性运动性能的改善。这些结果提供了证据表明 PKA 是小脑浦肯野细胞中 ATXN1-pS776 的一种重要的生物学激酶。
