Kittilukkana Aiyarin, Carmona Asuncion, Pilapong Chalermchai, Ortega Richard
Chiang Mai University, Faculty of Associated Medical Sciences, Department of Radiologic Technology, Center of Excellence for Molecular Imaging (CEMI), 50200 Chiang Mai, Thailand.
University Bordeaux, CNRS, LP2I Bordeaux, UMR 5797, Chemical Imaging and Speciation, F-33170 Gradignan, France.
Metallomics. 2024 Jan 5;16(1). doi: 10.1093/mtomcs/mfad074.
Iron dyshomeostasis is involved in many neurological disorders, particularly neurodegenerative diseases where iron accumulates in various brain regions. Identifying mechanisms of iron transport in the brain is crucial for understanding the role of iron in healthy and pathological states. In neurons, it has been suggested that iron can be transported by the axon to different brain regions in the form of labile iron; a pool of reactive and exchangeable intracellular iron. Here we report a novel approach to imaging labile ferrous iron, Fe(II), in live primary hippocampal neurons using confocal and TauSTED (stimulated emission depletion) microscopy. TauSTED is based on super-resolution STED nanoscopy, which combines high spatial resolution imaging (<40 nm) with fluorescence lifetime information, thus reducing background noise and improving image quality. We applied TauSTED imaging utilizing biotracker FerroFarRed Fe(II) and found that labile iron was present as submicrometric puncta in dendrites and axons. Some of these iron-rich structures are mobile and move along neuritic pathways, arguing for a labile iron transport mechanism in neurons. This super-resolution imaging approach offers a new perspective for studying the dynamic mechanisms of axonal and dendritic transport of iron at high spatial resolution in living neurons. In addition, this methodology could be transposed to the imaging of other fluorescent metal sensors.
铁稳态失衡与许多神经系统疾病有关，尤其是神经退行性疾病，在这些疾病中，铁会在大脑的各个区域累积。确定大脑中铁运输的机制对于理解铁在健康和病理状态下的作用至关重要。在神经元中，有人提出铁可以以不稳定铁的形式通过轴突运输到不同的脑区；不稳定铁是一种具有反应性和可交换性的细胞内铁池。在这里，我们报告了一种使用共聚焦显微镜和TauSTED（受激发射损耗）显微镜对原代海马神经元中的不稳定亚铁离子（Fe(II)）进行成像的新方法。TauSTED基于超分辨率STED纳米显微镜，它将高空间分辨率成像（<40nm）与荧光寿命信息相结合，从而降低背景噪声并提高图像质量。我们应用TauSTED成像技术，利用生物追踪剂FerroFarRed Fe(II)，发现不稳定铁以亚微米级的斑点形式存在于树突和轴突中。其中一些富含铁的结构是可移动的，并沿着神经突路径移动，这表明神经元中存在不稳定铁运输机制。这种超分辨率成像方法为在活神经元中以高空间分辨率研究铁的轴突和树突运输的动态机制提供了新的视角。此外，这种方法可以应用于其他荧光金属传感器的成像。
