Effect of overexpression of cathepsin E and Bcl-2 on neuronal death

在过去的几年里，人们一直关注与不同的神经病理条件下的细胞内蛋白水解系统的改变，在本研究中，我们已经确定了与组织蛋白酶E，一种非溶酶体天冬氨酸蛋白酶，蛋白水解事件与各种神经元变性过程的关联。首先，年龄相关的组织蛋白酶E的表达和定位的变化，确定在大鼠大脑皮层和脑干。这种酶在胚胎阶段的这些组织中几乎检测不到，而在出生后随着年龄的增长，它在这些组织中的表达越来越多。组织蛋白酶E与溶酶体天冬氨酸蛋白酶组织蛋白酶E共定位于老化神经元中含有脂褐素的溶酶体中。结果表明，衰老导致神经元中组织蛋白酶E的表达和定位增加，以及内体/溶酶体蛋白水解系统的变化，这可能与脂质合成有关。第二，组织蛋白酶B被证明是 关于我们 在各种脑细胞类型中，在小胶质细胞中最丰富，其中该酶主要作为内体中的成熟酶存在。第三，我们研究了Bcl-2过表达对成年转基因小鼠中在神经元特异性烯醇化酶控制下过表达人Bcl-2的海马CA 1区神经元和缺氧缺血诱导的齿状颗粒细胞的选择性神经元死亡的影响。结果表明，Bcl-2过表达可有效抑制齿状回颗粒细胞凋亡，但仅延迟CA 1区神经元的死亡，提示CA 1区神经元的死亡可能存在非凋亡性、非caspase依赖性机制。第四，当用活化的小胶质细胞处理时，神经元PC 12细胞经历凋亡，伴随着半胱天冬酶-3样蛋白酶活化和DNA片段化。用半胱天冬酶-3样蛋白酶抑制剂预处理神经元细胞并不能逆转这种细胞死亡。Bcl-2过表达也不能抑制活化的小胶质细胞诱导的神经元死亡。本研究通过阻断caspase-3蛋白酶级联反应为活化的小胶质细胞诱导的神经元死亡提供了另一种死亡途径。少

In past years attention has been paid to the altered intracellular proteolytic system in relation to different neuropathological conditions, In this study, we have determined the association of the proteolytic events relating to cathepsin E, a non-lysosomal aspartic proteinase, with various neuronal degeneration process. First, age-related changes in the expression and localization of cathepsin E was determined in the rat cerebral cortex and the brainstem. The enzyme was barely detectable in these tissues in the embryonic stages, whereas it was increasingly expressed in these tissues with aging after birth. cathepsin E was colocalized with the lysosomal aspartic proteinase cathepsin E in the lipofuscin-containing lysosomes in the aged neurons. The results indicate that aging results in the increased expression and localization of cathepsin E in neurons and changes in the endosomal/lysosomal proteolytic system, which may be related to lipofucigenesis. Second, cathepsin B was shown to be … More the most abundant in microglia among various brain cell types, where the enzyme existed predominantly as the mature enzyme in the endosome. Third, we have examined effects of Bcl-2 overexpression on selective neuronal death of the hippocampal CA1 neurons and the dentate granule cells induced by hypoxic-ischemia in adult transgenic mice overexpressing human Bcl-2 under the control of neuron-specific enolase. The results indicate that the overexpression of Bcl-2 effectively suppressed dentate granule cell apoptosis but only delayed cell death of the CA1 neurons, suggesting the occurrence of non-apoptiotic, caspase-independent mechanism for neuronal death in the CA1 subfield. Fourth, when treated with activated microglia, neuronal PC12 cells undergo apoptosis accompanied by caspase-3-like protease activation and DNA fragmentation. Pretreatment of the neuronal cells with caspase-3-like protease inhibitors did not reverse this cell death. Bcl-2 overexpression also could not suppress the activated microglia-induced neuronal death. this study provides an alternative death pathway for activated microglia- induced neuronal death by blockage of the caspase-3 protease cascade. Less