Centre for Membrane Pumps in Cells and Disease-PUMPKIN, Danish National Research Foundation, DK-1057 Copenhagen, Denmark.
J Biol Chem. 2013 Mar 29;288(13):8862-74. doi: 10.1074/jbc.M112.421529. Epub 2013 Feb 11.
Na(+)/K(+)-ATPases are transmembrane ion pumps that maintain ion gradients across the basolateral plasma membrane in all animal cells to facilitate essential biological functions. Mutations in the Na(+)/K(+)-ATPase α3 subunit gene (ATP1A3) cause rapid-onset dystonia-parkinsonism, a rare movement disorder characterized by sudden onset of dystonic spasms and slow movements. In the brain, ATP1A3 is principally expressed in neurons. In zebrafish, the transcripts of the two ATP1A3 orthologs, Atp1a3a and Atp1a3b, show distinct expression in the brain. Surprisingly, targeted knockdown of either Atp1a3a or Atp1a3b leads to brain ventricle dilation, a likely consequence of ion imbalances across the plasma membrane that cause accumulation of cerebrospinal fluid in the ventricle. The brain ventricle dilation is accompanied by a depolarization of spinal Rohon-Beard neurons in Atp1a3a knockdown embryos, suggesting impaired neuronal excitability. This is further supported by Atp1a3a or Atp1a3b knockdown results where altered responses to tactile stimuli as well as abnormal motility were observed. Finally, proteomic analysis identified several protein candidates highlighting proteome changes associated with the knockdown of Atp1a3a or Atp1a3b. Our data thus strongly support the role of α3Na(+)/K(+)-ATPase in zebrafish motility and brain development, associating for the first time the α3Na(+)/K(+)-ATPase deficiency with brain ventricle dilation.
Na(+)/K(+)-ATPases 是一种跨膜离子泵，它维持着所有动物细胞基底外侧质膜的离子梯度，从而促进基本的生物功能。Na(+)/K(+)-ATPase α3 亚基基因 (ATP1A3) 的突变会导致发作性肌张力障碍-帕金森病，这是一种罕见的运动障碍，其特征是突然出现肌张力障碍痉挛和运动缓慢。在大脑中，ATP1A3 主要在神经元中表达。在斑马鱼中，两种 ATP1A3 同源物 Atp1a3a 和 Atp1a3b 的转录本在大脑中表现出明显的表达。令人惊讶的是，靶向敲低 Atp1a3a 或 Atp1a3b 都会导致脑室扩张，这很可能是由于质膜两侧离子失衡导致脑脊液在脑室中积聚所致。脑室扩张伴随着 Atp1a3a 敲低胚胎中脊髓 Rohon-Beard 神经元的去极化，表明神经元兴奋性受损。这进一步得到了 Atp1a3a 或 Atp1a3b 敲低的结果的支持，在这些结果中观察到对触觉刺激的反应改变和异常运动。最后，蛋白质组学分析鉴定出了几个蛋白候选物，突出了与 Atp1a3a 或 Atp1a3b 敲低相关的蛋白质组变化。因此，我们的数据强烈支持α3Na(+)/K(+)-ATPase 在斑马鱼运动和大脑发育中的作用，首次将α3Na(+)/K(+)-ATPase 缺陷与脑室扩张联系起来。
