Takasawa Akira, Kato Ichiro, Takasawa Kumi, Ishii Yoko, Yoshida Toshiko, Shehata Mohammad H, Kawaguchi Hiroshi, Mohafez Omar M M, Sasahara Masakiyo, Hiraga Koichi
Department of Biochemistry, University of Toyama, Graduate School of Medicine and Pharmaceutical Sciences, 2630 Sugitani, Toyama 930-0194, Japan.
J Biol Chem. 2008 Dec 19;283(51):35606-13. doi: 10.1074/jbc.M804125200. Epub 2008 Oct 21.
Mutations in human neuroserpin gene cause an autosomal dementia, familial encephalopathy with neuroserpin inclusion bodies (FENIB). We generated and analyzed transgenic mice expressing high levels of either FENIB-type (G392E) or wild-type human neuroserpin in neurons of the central nervous system. G392E neuroserpin accumulated age-dependently in neurons of the neocortex, thalamus, amygdala, pons, and spinal cord of homozygous transgenic mice. Such accumulations were not observed in hemizygous transgenic mice nor in transgenic mice for wild-type neuroserpin. In differential centrifugation of brain homogenates, G392E neuroserpin recovered in the nucleus-rich fraction dramatically increased along with aging, suggesting that the aggregations gradually increase their densities presumably by their conversion into heavier and more compact configurations. In immunoelectron microscopical analyses, immunopositivities for G392E neuroserpin were found not only in endoplasmic reticulum but also in lysosomes. G392E neuroserpin transgenic mice were much more susceptible to seizures induced by kainate administration than nontransgenic mice. Overall, G392E neuroserpin accumulated in the central nervous system neurons of transgenic mice in mutation-, aging-, and gene dosage-dependent manners. The established transgenic mice will be valuable to elucidate not only mechanisms for the formation of G392E neuroserpin aggregations but also pathways for the degradation and/or clearance of the already formed aggregations in neurons.
人类神经丝氨酸蛋白酶抑制剂基因的突变会导致一种常染色体显性痴呆症，即伴有神经丝氨酸蛋白酶抑制剂包涵体的家族性脑病（FENIB）。我们构建并分析了在中枢神经系统神经元中高水平表达FENIB型（G392E）或野生型人类神经丝氨酸蛋白酶抑制剂的转基因小鼠。G392E神经丝氨酸蛋白酶抑制剂在纯合转基因小鼠的新皮层、丘脑、杏仁核、脑桥和脊髓的神经元中随年龄增长而积累。在半合子转基因小鼠或野生型神经丝氨酸蛋白酶抑制剂转基因小鼠中未观察到这种积累。在脑匀浆的差速离心中，富含细胞核部分中回收的G392E神经丝氨酸蛋白酶抑制剂随着衰老显著增加，这表明聚集物可能通过转变为更重、更紧密的结构而逐渐增加其密度。在免疫电子显微镜分析中，G392E神经丝氨酸蛋白酶抑制剂的免疫阳性不仅在内质网中发现，也在溶酶体中发现。与非转基因小鼠相比，G392E神经丝氨酸蛋白酶抑制剂转基因小鼠对海藻酸诱导的癫痫发作更敏感。总体而言，G392E神经丝氨酸蛋白酶抑制剂以突变、年龄和基因剂量依赖的方式在转基因小鼠的中枢神经系统神经元中积累。所建立的转基因小鼠不仅对于阐明G392E神经丝氨酸蛋白酶抑制剂聚集物的形成机制，而且对于阐明神经元中已形成聚集物的降解和/或清除途径都将是有价值的。
