Lysosomal membrane permeabilization and autophagy blockade contribute to photoreceptor cell death in a mouse model of retinitis pigmentosa
Lysosomal membrane permeabilization and autophagy blockade contribute to photoreceptor cell death in a mouse model of retinitis pigmentosa
复制标题
溶酶体膜透化和自噬阻断导致色素性视网膜炎小鼠模型中感光细胞死亡
DOI：
10.1038/cdd.2014.203
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发表时间：
2015-03-01
影响因子：
12.4
通讯作者：
Boya, P.
中科院分区：
文献类型：
--
作者：
Rodriguez-Muela, N.;Hernandez-Pinto, Am;Boya, P.
视网膜色素变性是一组遗传性视网膜营养不良，在动物模型和患者中通常会导致光感受器细胞死亡和视力丧失。携带Pde6b基因错义突变的rd10小鼠已被用于表征潜在的病理生理学，并开发这种毁灭性和不可治愈的疾病的治疗方法。在这里，我们证明了RD10小鼠视网膜中光感受器细胞死亡的增加与钙超载和钙蛋白酶激活有关，这两种情况都是在细胞退化迹象出现之前观察到的。伴随这些变化的是光感受器细胞胞浆中溶酶体蛋白水解酶组织蛋白酶B活性的增加，以及组织蛋白酶B与溶酶体标记物共定位的减少，这表明溶酶体膜通透性发生在细胞死亡高峰之前。此外，在光感受器细胞死亡开始之前，自噬标记Lc3-II(Lc3的脂化形式)的表达减少，自噬通量在RD10视网膜中被阻断。有趣的是，我们发现细胞死亡是通过雷帕霉素诱导自噬而增加的，并被体外和体内的钙蛋白酶和组织蛋白酶抑制剂所抑制。综上所述，这些数据表明，钙蛋白酶介导的溶酶体膜通透性是与光感受器细胞死亡相关的溶酶体功能障碍和自噬下调的基础。
Retinitis pigmentosa is a group of hereditary retinal dystrophies that normally result in photoreceptor cell death and vision loss both in animal models and in affected patients. The rd10 mouse, which carries a missense mutation in the Pde6b gene, has been used to characterize the underlying pathophysiology and develop therapies for this devastating and incurable disease. Here we show that increased photoreceptor cell death in the rd10 mouse retina is associated with calcium overload and calpain activation, both of which are observed before the appearance of signs of cell degeneration. These changes are accompanied by an increase in the activity of the lysosomal protease cathepsin B in the cytoplasm of photoreceptor cells, and a reduced colocalization of cathepsin B with lysosomal markers, suggesting that lysosomal membrane permeabilization occurs before the peak of cell death. Moreover, expression of the autophagosomal marker LC3-II (lipidated form of LC3) is reduced and autophagy flux is blocked in rd10 retinas before the onset of photoreceptor cell death. Interestingly, we found that cell death is increased by the induction of autophagy with rapamycin and inhibited by calpain and cathepsin inhibitors, both ex vivo and in vivo. Taken together, these data suggest that calpain-mediated lysosomal membrane permeabilization underlies the lysosomal dysfunction and downregulation of autophagy associated with photoreceptor cell death.