Department of Molecular Biology, Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390
Department of Biology, University of Louisiana at Lafayette, Lafayette, Louisiana 70503.
J Neurosci. 2021 Mar 3;41(9):2024-2038. doi: 10.1523/JNEUROSCI.2507-20.2020. Epub 2021 Jan 19.
DYT1 dystonia is a hereditary neurologic movement disorder characterized by uncontrollable muscle contractions. It is caused by a heterozygous mutation in (), a gene encoding a membrane-embedded ATPase. While animal models provide insights into disease mechanisms, significant species-dependent differences exist since animals with the identical heterozygous mutation fail to show pathology. Here, we model DYT1 by using human patient-specific cholinergic motor neurons (MNs) that are generated through either direct conversion of patients' skin fibroblasts or differentiation of induced pluripotent stem cells (iPSCs). These human MNs with the heterozygous mutation show reduced neurite length and branches, markedly thickened nuclear lamina, disrupted nuclear morphology, and impaired nucleocytoplasmic transport (NCT) of mRNAs and proteins, whereas they lack the perinuclear "blebs" that are often observed in animal models. Furthermore, we uncover that the nuclear lamina protein LMNB1 is upregulated in DYT1 cells and exhibits abnormal subcellular distribution in a cholinergic MNs-specific manner. Such dysregulation of LMNB1 can be recapitulated by either ectopic expression of the mutant gene or shRNA-mediated downregulation of endogenous in healthy control MNs. Interestingly, downregulation of LMNB1 can largely ameliorate all the cellular defects in DYT1 MNs. These results reveal the value of disease modeling with human patient-specific neurons and indicate that dysregulation of LMNB1, a crucial component of the nuclear lamina, may constitute a major molecular mechanism underlying DYT1 pathology. Inaccessibility to patient neurons greatly impedes our understanding of the pathologic mechanisms for dystonia. In this study, we employ reprogrammed human patient-specific motor neurons (MNs) to model DYT1, the most severe hereditary form of dystonia. Our results reveal disease-dependent deficits in nuclear morphology and nucleocytoplasmic transport (NCT). Most importantly, we further identify LMNB1 dysregulation as a major contributor to these deficits, uncovering a new pathologic mechanism for DYT1 dystonia.
DYT1 型肌张力障碍是一种遗传性神经系统运动障碍，其特征是肌肉无法控制地收缩。它是由编码一种膜嵌入 ATP 酶的基因突变引起的。虽然动物模型为疾病机制提供了深入的了解，但由于具有相同杂合突变的动物未能表现出病理学，因此存在显著的物种依赖性差异。在这里，我们通过使用通过患者皮肤成纤维细胞的直接转化或诱导多能干细胞（iPSC）分化产生的人类患者特异性胆碱能运动神经元（MNs）来模拟 DYT1。这些具有杂合 突变的人 MNs 显示出神经突长度和分支减少，核层明显增厚，核形态破坏以及 mRNA 和蛋白质的核质转运（NCT）受损，而缺乏动物模型中经常观察到的核周“泡”。此外，我们发现核层蛋白 LMNB1 在 DYT1 细胞中上调，并以胆碱能 MNs 特异性方式表现出异常的亚细胞分布。这种 LMNB1 的失调可以通过突变体 基因的异位表达或健康对照 MN 中内源性 基因的 shRNA 介导下调来重现。有趣的是，LMNB1 的下调可以在很大程度上改善 DYT1 MN 中的所有细胞缺陷。这些结果揭示了使用人类患者特异性神经元进行疾病建模的价值，并表明核层关键组成部分 LMNB1 的失调可能构成 DYT1 病理学的主要分子机制。无法获得患者神经元极大地阻碍了我们对肌张力障碍病理机制的理解。在这项研究中，我们使用重编程的人类患者特异性运动神经元（MNs）来模拟 DYT1，这是最严重的遗传性肌张力障碍形式。我们的结果揭示了核形态和核质转运（NCT）的疾病依赖性缺陷。最重要的是，我们进一步确定 LMNB1 失调是这些缺陷的主要原因之一，为 DYT1 肌张力障碍揭示了新的病理机制。
