Casadei Nicolas, Sood Poonam, Ulrich Thomas, Fallier-Becker Petra, Kieper Nicole, Helling Stefan, May Caroline, Glaab Enrico, Chen Jing, Nuber Silke, Wolburg Hartwig, Marcus Katrin, Rapaport Doron, Ott Thomas, Riess Olaf, Krüger Rejko, Fitzgerald Julia C
Institute of Medical Genetics and Applied Genomics, University of Tübingen, Calwerstrasse 7, 72076 Tübingen, Germany.
Graduate School of Cellular and Molecular Neuroscience, University of Tübingen, Tübingen, Germany, Functional Neurogenomics Laboratory, Department of Neurodegenerative Diseases, Hertie Institute for Clinical Brain Research and, Centre for Integrative Neuroscience (CIN), University of Tübingen, Otfried-Mueller-Strasse 27, Tübingen 72076, Germany, The German Centre for Neurodegenerative Diseases (DZNE), Tübingen, Germany.
Hum Mol Genet. 2016 Feb 1;25(3):459-71. doi: 10.1093/hmg/ddv485. Epub 2015 Nov 24.
The protease HtrA2 has a protective role inside mitochondria, but promotes apoptosis under stress. We previously identified the G399S HtrA2 mutation in Parkinson's disease (PD) patients and reported mitochondrial dysfunction in vitro. Mitochondrial dysfunction is a common feature of PD and related to neurodegeneration. Complete loss of HtrA2 has been shown to cause neurodegeneration in mice. However, the full impact of HtrA2 overexpression or the G399S mutation is still to be determined in vivo. Here, we report the first HtrA2 G399S transgenic mouse model. Our data suggest that the mutation has a dominant-negative effect. We also describe a toxic effect of wild-type (WT) HtrA2 overexpression. Only low overexpression of the G399S mutation allowed viable animals and we suggest that the mutant protein is likely unstable. This is accompanied by reduced mitochondrial respiratory capacity and sensitivity to apoptotic cell death. Mice overexpressing WT HtrA2 were viable, yet these animals have inhibited mitochondrial respiration and significant induction of apoptosis in the brain leading to motor dysfunction, highlighting the opposing roles of HtrA2. Our data further underscore the importance of HtrA2 as a key mediator of mitochondrial function and its fine regulatory role in cell fate. The location and abundance of HtrA2 is tightly controlled and, therefore, human mutations leading to gain- or loss of function could provide significant risk for PD-related neurodegeneration.
蛋白酶HtrA2在线粒体内具有保护作用，但在应激状态下会促进细胞凋亡。我们之前在帕金森病（PD）患者中鉴定出G399S HtrA2突变，并报道了其在体外的线粒体功能障碍。线粒体功能障碍是PD的一个常见特征，与神经退行性变有关。研究表明，HtrA2的完全缺失会导致小鼠神经退行性变。然而，HtrA2过表达或G399S突变的全面影响仍有待在体内确定。在此，我们报道首个HtrA2 G399S转基因小鼠模型。我们的数据表明该突变具有显性负效应。我们还描述了野生型（WT）HtrA2过表达的毒性作用。只有低水平过表达G399S突变才能产生存活的动物，我们认为突变蛋白可能不稳定。这伴随着线粒体呼吸能力降低以及对凋亡性细胞死亡的敏感性增加。过表达WT HtrA2的小鼠能够存活，但这些动物的线粒体呼吸受到抑制，大脑中细胞凋亡显著增加，导致运动功能障碍，突出了HtrA2的相反作用。我们的数据进一步强调了HtrA2作为线粒体功能关键调节因子的重要性及其在细胞命运中的精细调节作用。HtrA2的定位和丰度受到严格控制，因此，导致功能获得或丧失的人类突变可能会给PD相关的神经退行性变带来重大风险。
