Garden G A, Hartlage-Rübsamen M, Rubel E W, Bothwell M A
Virginia Merrill Bloedel Hearing Research Center, Department of Physiology and Biophysics, Seattle, Washington, USA.
Mol Cell Neurosci. 1995 Jun;6(3):293-310. doi: 10.1006/mcne.1995.1023.
Cell death in the developing nervous system is regulated by both afferent synaptic activity and target-derived neurotrophic factors. Loss of afferent innervation via unilateral cochlea removal results in the death of 20-40% of neurons in the neonatal chick cochlear nucleus, nucleus magnocellularis (NM). The process of NM neuronal death involves structural and functional alterations in ribosomes, including decreased protein synthesis, loss of immunoreactivity for a monoclonal anti-ribosomal RNA (rRNA) antibody, Y10B, and eventual ribosome degradation. In the present report we confirm that the Y10B antibody binds specifically to ribosomes in chick NM neurons by electron microscopy. We then performed experiments designed to determine whether loss of rRNA immunoreactivity observed in NM neurons following cochlea removal involves induction of a protein-rRNA interaction. Brain stem tissue from animals subjected to unilateral cochlea removal was treated with protease prior to immunolabeling. Protease treatment restored rRNA immunoreactivity after 3 h of afferent deprivation, confirming that afferent deprivation induces protein-rRNA interactions which mask the Y10B epitope. Immunoprecipitation experiments confirmed that the Y10B antibody recognizes a specific rRNA sequence without posttranscriptional modification.
发育中的神经系统中的细胞死亡受传入突触活动和靶源性神经营养因子的共同调节。通过单侧切除耳蜗导致传入神经支配丧失，会致使新生雏鸡耳蜗核大细胞（NM）中20%-40%的神经元死亡。NM神经元死亡过程涉及核糖体的结构和功能改变，包括蛋白质合成减少、针对单克隆抗核糖体RNA（rRNA）抗体Y10B的免疫反应性丧失以及最终的核糖体降解。在本报告中，我们通过电子显微镜证实Y10B抗体特异性结合雏鸡NM神经元中的核糖体。然后我们进行了实验，以确定在切除耳蜗后NM神经元中观察到的rRNA免疫反应性丧失是否涉及蛋白质-rRNA相互作用的诱导。在免疫标记之前，对接受单侧耳蜗切除的动物的脑干组织进行蛋白酶处理。蛋白酶处理在传入剥夺3小时后恢复了rRNA免疫反应性，证实传入剥夺诱导了掩盖Y10B表位的蛋白质-rRNA相互作用。免疫沉淀实验证实Y10B抗体识别特定的rRNA序列且无需转录后修饰。
