帕金森病是一种在老龄群体中高发的中枢神经系统退行性疾病，尽管已知衰老是重要诱因之一，但科学家对帕金森神经细胞退行性病变的原因和发病机理尚不清楚。近日，《自然》杂志在线发表了中科院生物物理所刘光慧研究组与美国研究人员的合作研究论文。该研究首次结合多能干细胞和基因组靶向修饰技术揭示了帕金森病神经干细胞随着衰老过程而发生的退行性病变。这一研究成果为诊断、预防与治疗帕金森病提供了新的潜在靶点。
研究人员首先向携带帕金森病致病基因LRRK2(G2019S)突变的患者皮肤细胞中导入3个多能性因子，从而在体外获得疾病特异的诱导性多能干细胞（iPSC）。这些iPSC在实验室中进一步定向分化为目前无法从患者颅内直接获取的功能性神经干细胞及多巴胺神经元。通过研究，刘光慧等发现LRRK2(G2019S)突变的神经干细胞表现出一系列与“衰老”相关的退行性表型。
而矫正后的神经干细胞消除了帕金森病相关的疾病表型。相反，利用打靶技术在正常人胚胎干细胞中定向敲入LRRK2(G2019S)突变（即体外人工创造出帕金森病胚胎干细胞）则导致疾病相关表型的出现。更为重要的是，通过对临床帕金森病人死后脑组织的海马区（人神经干细胞所在部位）进行分析，可见该区神经源性细胞存在广泛的核膜异常，这与帕金森病iPSC定向分化得到的神经干细胞模型观察结果一致。研究人员进一步发现，LRRK2激酶特异性抑制剂可以在体外改善帕金森神经干细胞的异常表型。
这一工作首次揭示了核膜异常及脑内神经干细胞渐进性功能衰退在帕金森病发生发展中的作用。不仅为帕金森病病人患有的认知功能衰退等中枢神经系统症状提供了一定解释，还提示了临床上利用小分子抑制剂药物或靶向基因修复患者神经前体细胞治疗帕金森病的可能性。
Progressive degeneration of human neural stem cells caused by pathogenic LRRK2
Guang-Hui Liu, Jing Qu, Keiichiro Suzuki, Emmanuel Nivet, Mo Li, Nuria Montserrat, Fei Yi, Xiuling Xu, Sergio Ruiz, Weiqi Zhang, Ulrich Wagner, Audrey Kim, Bing Ren, Ying Li, April Goebl, Jessica Kim, Rupa Devi Soligalla, Ilir Dubova, James Thompson, John Yates III, Concepcion Rodriguez Esteban, Ignacio Sancho-Martinez & Juan Carlos Izpisua Belmonte
Nuclear-architecture defects have been shown to correlate with the manifestation of a number of human diseases as well as ageing. It is therefore plausible that diseases whose manifestations correlate with ageing might be connected to the appearance of nuclear aberrations over time. We decided to evaluate nuclear organization in the context of ageing-associated disorders by focusing on a leucine-rich repeat kinase 2 (LRRK2) dominant mutation (G2019S; glycine-to-serine substitution at amino acid 2019), which is associated with familial and sporadic Parkinson’s disease as well as impairment of adult neurogenesis in mice5. Here we report on the generation of induced pluripotent stem cells (iPSCs) derived from Parkinson’s disease patients and the implications of LRRK2(G2019S) mutation in human neural-stem-cell (NSC) populations. Mutant NSCs showed increased susceptibility to proteasomal stress as well as passage-dependent deficiencies in nuclear-envelope organization, clonal expansion and neuronal differentiation. Disease phenotypes were rescued by targeted correction of the LRRK2(G2019S) mutation with its wild-type counterpart in Parkinson’s disease iPSCs and were recapitulated after targeted knock-in of the LRRK2(G2019S) mutation in human embryonic stem cells. Analysis of human brain tissue showed nuclear-envelope impairment in clinically diagnosed Parkinson’s disease patients. Together, our results identify the nucleus as a previously unknown cellular organelle in Parkinson’s disease pathology and may help to open new avenues for Parkinson’s disease diagnoses as well as for the potential development of therapeutics targeting this fundamental cell structure.
文献链接：https://www.nature.com/nature/journal/vaop/ncurrent/full/nature11557.html
