Francis J W, Sandrock A W, Bhide P G, Vonsattel J P, Brown R H
Department of Neurology, Massachusetts General Hospital and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA.
Proc Natl Acad Sci U S A. 1998 May 26;95(11):6492-7. doi: 10.1073/pnas.95.11.6492.
Spinal muscular atrophy is caused by defects in the survival motor neuron (SMN) gene. To better understand the patterns of expression of SMN in neuronal cells and tissues, we raised a polyclonal antibody (abSMN) against a synthetic oligopeptide from SMN exon 2. AbSMN immunostaining in neuroblastoma cells and mouse and human central nervous system (CNS) showed intense labeling of nuclear "gems," along with prominent nucleolar immunoreactivity in mouse and human CNS tissues. Strong cytoplasmic labeling was observed in the perikarya and proximal dendrites of human spinal motor neurons but not in their axons. Immunoblot analysis revealed a 34-kDa species in the insoluble protein fractions from human SY5Y neuroblastoma cells, embryonic mouse spinal cord cultures, and human CNS tissue. By contrast, a 38-kDa species was detected in the cytosolic fraction of SY5Y cells. We conclude that SMN protein is expressed prominently in both the cytoplasm and nucleus in multiple types of neurons in brain and spinal cord, a finding consistent with a role for SMN as a determinant of neuronal viability.
脊髓性肌萎缩症是由存活运动神经元（SMN）基因缺陷引起的。为了更好地了解SMN在神经元细胞和组织中的表达模式，我们针对来自SMN外显子2的合成寡肽制备了一种多克隆抗体（abSMN）。在神经母细胞瘤细胞以及小鼠和人类中枢神经系统（CNS）中进行的abSMN免疫染色显示，核“宝石”有强烈标记，同时在小鼠和人类CNS组织中核仁有明显的免疫反应性。在人类脊髓运动神经元的胞体和近端树突中观察到强烈的细胞质标记，但在其轴突中未观察到。免疫印迹分析显示，在来自人类SY5Y神经母细胞瘤细胞、胚胎小鼠脊髓培养物和人类CNS组织的不溶性蛋白组分中有一种34 kDa的蛋白条带。相比之下，在SY5Y细胞的胞质组分中检测到一种38 kDa的蛋白条带。我们得出结论，SMN蛋白在脑和脊髓的多种类型神经元的细胞质和细胞核中均有显著表达，这一发现与SMN作为神经元活力决定因素的作用一致。
