Miyajima T, Ohta E, Kawada H, Maekawa T, Obata F
Division of Clinical Immunology, Kitasato University Graduate School of Medicine, Kanagawa, Japan.
Division of Clinical Immunology, Kitasato University Graduate School of Medicine, Kanagawa, Japan; Research Facility Center for Regenerative Medicine and Cell Design, Kitasato University School of Allied Health Sciences, Kanagawa, Japan.
Neurosci Lett. 2015 Feb 19;588:142-6. doi: 10.1016/j.neulet.2015.01.003. Epub 2015 Jan 3.
Leucine-rich repeat kinase (LRRK2) is the causal molecule of autosomal dominant Parkinson's disease (PD). We previously reported that intracellular degradation of wild-type (WT) LRRK2 is promoted by formation of heterodimers with the I2020T mutant LRRK2. In the present study, we investigated whether this is also the case for mouse/human cross-species heterodimers, which could be formed in transgenic mice. First, by co-transfection and immunoprecipitation, we identified the cross-species heterodimer of mouse LRRK2 and human LRRK2. Next, we found that the protein level of mouse LRRK2 decreased when co-transfected with human I2020T LRRK2, but not with human WT LRRK2. These results suggested that degradation of mouse LRRK2 was promoted by formation of a cross-species heterodimer with the mutant LRRK2. In I2020T LRRK2-transgenic mice, the lower protein level of brain LRRK2 in comparison with control mice, together with higher expression of the mRNA, suggested that endogenous LRRK2 was degraded by formation of cross-species heterodimers. Our results suggest a new concept of cross-species dimer/oligomer formation in transgenic disease-model mice.
富含亮氨酸重复序列激酶（LRRK2）是常染色体显性帕金森病（PD）的致病分子。我们之前报道过，野生型（WT）LRRK2的细胞内降解是由与I2020T突变型LRRK2形成异源二聚体所促进的。在本研究中，我们调查了在转基因小鼠中可能形成的小鼠/人类跨物种异源二聚体是否也是这种情况。首先，通过共转染和免疫沉淀，我们鉴定出了小鼠LRRK2和人类LRRK2的跨物种异源二聚体。接下来，我们发现当与人类I2020T LRRK2共转染时，小鼠LRRK2的蛋白水平降低，但与人类WT LRRK2共转染时则不然。这些结果表明，与突变型LRRK2形成跨物种异源二聚体促进了小鼠LRRK2的降解。在I2020T LRRK2转基因小鼠中，与对照小鼠相比，脑LRRK2的蛋白水平较低，同时mRNA表达较高，这表明内源性LRRK2是通过形成跨物种异源二聚体而被降解的。我们的结果提示了转基因疾病模型小鼠中跨物种二聚体/寡聚体形成的新概念。
