Lysosomal dysfunction and impaired autophagy in a novel mouse model deficient for the lysosomal membrane protein Cln7
Lysosomal dysfunction and impaired autophagy in a novel mouse model deficient for the lysosomal membrane protein Cln7
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DOI：
10.1093/hmg/ddv615
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发表时间：
2016-02-15
影响因子：
3.5
通讯作者：
Storch, Stephan
中科院分区：
文献类型：
--
作者：
Brandenstein, Laura;Schweizer, Michaela;Storch, Stephan
CLN 7疾病是一种常染色体隐性遗传、儿童期发作的神经退行性溶酶体贮积症，由缺陷性溶酶体膜蛋白CLN 7引起。我们已经通过外显子2的靶向缺失破坏了小鼠中的Cln 7/Mfsd 8基因，产生了用于CLN 7疾病的新型敲除（KO）小鼠模型，其概括了人CLN 7疾病病理学的关键特征。Cln 7 KO小鼠表现出增加的死亡率和神经学表型，包括后肢紧握和肌阵挛。突变小鼠脑中溶酶体功能障碍表现为自发荧光脂褐素样脂色素、线粒体ATP合酶c亚基和saposin D的储存以及溶酶体组织蛋白酶B、D和Z的表达增加。通过免疫组化共染色，增加组织蛋白酶Z表达仅限于Cln 7缺陷的小胶质细胞和neurons. Ultrasstructural分析发现，在浦肯野细胞的Cln 7基因敲除小鼠包含不规则的，曲线和直线的配置文件，以及指纹配置文件组成的大存储体。在Cln 7 KO小鼠中，在嗅球、大脑皮质和小脑中的神经变性之前，大脑中的普遍性星形胶质细胞增生和小胶质细胞增生。LC 3-II水平的增加以及神经元p62和泛素阳性蛋白聚集体的存在表明，受损的自噬是Cln 7 KO小鼠脑中的主要病理机制。数据表明，脑中推定的溶酶体转运蛋白Cln 7的丢失导致疾病后期的溶酶体功能障碍、受损的组成性自噬和神经变性。
CLN7 disease is an autosomal recessive, childhood-onset neurodegenerative lysosomal storage disorder caused by the defective lysosomal membrane protein CLN7. We have disrupted the Cln7/Mfsd8 gene in mice by targeted deletion of exon 2 generating a novel knockout (KO) mouse model for CLN7 disease, which recapitulates key features of human CLN7 disease pathology. Cln7 KO mice showed increased mortality and a neurological phenotype including hind limb clasping and myoclonus. Lysosomal dysfunction in the brain of mutant mice was shown by the storage of autofluorescent lipofuscin-like lipopigments, subunit c of mitochondrial ATP synthase and saposin D and increased expression of lysosomal cathepsins B, D and Z. By immunohistochemical co-stainings, increased cathepsin Z expression restricted to Cln7-deficient microglia and neurons was found. Ultrastructural analyses revealed large storage bodies in Purkinje cells of Cln7 KO mice containing inclusions composed of irregular, curvilinear and rectilinear profiles as well as fingerprint profiles. Generalized astrogliosis and microgliosis in the brain preceded neurodegeneration in the olfactory bulb, cerebral cortex and cerebellum in Cln7 KO mice. Increased levels of LC3-II and the presence of neuronal p62- and ubiquitin-positive protein aggregates suggested that impaired autophagy represents a major pathomechanism in the brain of Cln7 KO mice. The data suggest that loss of the putative lysosomal transporter Cln7 in the brain leads to lysosomal dysfunction, impaired constitutive autophagy and neurodegeneration late in disease.