Verstraelen Peter, Detrez Jan R, Verschuuren Marlies, Kuijlaars Jacobine, Nuydens Rony, Timmermans Jean-Pierre, De Vos Winnok H
Laboratory of Cell Biology and Histology, Department of Veterinary Sciences, University of AntwerpAntwerp, Belgium.
Biomedical Research Institute, University of HasseltDiepenbeek, Belgium.
Front Cell Neurosci. 2017 Jun 22;11:173. doi: 10.3389/fncel.2017.00173. eCollection 2017.
Functionally related neurons assemble into connected networks that process and transmit electrochemical information. To do this in a coordinated manner, the number and strength of synaptic connections is tightly regulated. Synapse function relies on the microtubule (MT) cytoskeleton, the dynamics of which are in turn controlled by a plethora of MT-associated proteins, including the MT-stabilizing protein Tau. Although mutations in the Tau-encoding gene underlie a set of neurodegenerative disorders, termed tauopathies, the exact contribution of MT dynamics and the perturbation thereof to neuronal network connectivity has not yet been scrutinized. Therefore, we investigated the impact of targeted perturbations of MT stability on morphological (e.g., neurite- and synapse density) and functional (e.g., synchronous calcium bursting) correlates of connectivity in networks of primary hippocampal neurons. We found that treatment with MT-stabilizing or -destabilizing compounds impaired morphofunctional connectivity in a reversible manner. We also discovered that overexpression of induced significant connectivity defects, which were accompanied by alterations in MT dynamics and increased resistance to pharmacological MT depolymerization. Overexpression of a variant harboring the P301L point mutation in the MT-binding domain did far less, directly linking neuronal connectivity with Tau's MT binding affinity. Our results show that MT stability is a vulnerable node in tauopathies and that its precise pharmacological tuning may positively affect neuronal network connectivity. However, a critical balance in MT turnover causes it to be a difficult therapeutic target with a narrow operating window.
功能相关的神经元组装成相互连接的网络，这些网络处理和传递电化学信息。为了以协调的方式做到这一点，突触连接的数量和强度受到严格调控。突触功能依赖于微管（MT）细胞骨架，而微管的动态变化又受大量微管相关蛋白的控制，包括微管稳定蛋白Tau。尽管编码Tau的基因突变是一组神经退行性疾病（称为tau蛋白病）的基础，但微管动态变化及其扰动对神经网络连通性的确切影响尚未得到仔细研究。因此，我们研究了微管稳定性的靶向扰动对原代海马神经元网络连通性的形态学（如神经突和突触密度）和功能（如同步钙爆发）相关指标的影响。我们发现，用微管稳定或不稳定化合物处理会以可逆的方式损害形态功能连通性。我们还发现，[此处原文缺失相关蛋白名称]的过表达会导致明显的连通性缺陷，同时伴有微管动态变化的改变以及对药物性微管解聚的抗性增加。在微管结合结构域中携带P301L点突变的[此处原文缺失相关蛋白名称]变体的过表达影响要小得多，这直接将神经元连通性与Tau的微管结合亲和力联系起来。我们的结果表明微管稳定性是tau蛋白病中的一个脆弱节点，其精确的药物调节可能对神经网络连通性产生积极影响。然而，微管周转的关键平衡使其成为一个具有狭窄操作窗口的难以治疗的靶点。
