Marshall Moscon Savannah, Neely Elizabeth, Proctor Elizabeth, Connor James
Department of Neurosurgery, The Pennsylvania State University College of Medicine, Hershey, Pennsylvania, USA.
J Neurochem. 2024 Sep;168(9):3132-3153. doi: 10.1111/jnc.16171. Epub 2024 Jul 29.
The role of iron dyshomeostasis in neurodegenerative disease has implicated the involvement of genes that regulate brain iron. The homeostatic iron regulatory gene (HFE) has been at the forefront of these studies given the role of the H63D variant (H67D in mice) in increasing brain iron load. Despite iron's role in oxidative stress production, H67D mice have shown robust protection against neurotoxins and improved recovery from intracerebral hemorrhage. Previous data support the notion that H67D mice adapt to the increased brain iron concentrations and hence develop a neuroprotective environment. This adaptation is particularly evident in the lumbar spinal cord (LSC) and ventral midbrain (VM), both relevant to neurodegeneration. We studied C57BL6/129 mice with homozygous H67D compared to WT HFE. Immunohistochemistry was used to analyze dopaminergic (in the VM) and motor (in the LSC) neuron population maturation in the first 3 months. Immunoblotting was used to measure protein carbonyl content and the expression of oxidative phosphorylation complexes. Seahorse assay was used to analyze metabolism of mitochondria isolated from the LSC and VM. Finally, a Nanostring transcriptomic analysis of genes relevant to neurodegeneration within these regions was performed. Compared to WT mice, we found no difference in the viability of motor neurons in the LSC, but the dopaminergic neurons in H67D mice experienced significant decline before 3 months of age. Both regions in H67D mice had alterations in oxidative phosphorylation complex expression indicative of stress adaptation. Mitochondria from both regions of H67D mice demonstrated metabolic differences compared to WT. Transcriptional differences in these regions of H67D mice were related to cell structure and adhesion as well as cell signaling. Overall, we found that the LSC and VM undergo significant and distinct metabolic and transcriptional changes in adaptation to iron-related stress induced by the H67D HFE gene variant.
铁稳态失衡在神经退行性疾病中的作用涉及调节脑铁的基因。鉴于H63D变体（小鼠中的H67D）在增加脑铁负荷中的作用，稳态铁调节基因（HFE）一直处于这些研究的前沿。尽管铁在氧化应激产生中起作用，但H67D小鼠对神经毒素表现出强大的保护作用，并改善了脑出血后的恢复。先前的数据支持这样的观点，即H67D小鼠适应增加的脑铁浓度，从而形成神经保护环境。这种适应在与神经退行性变相关的腰脊髓（LSC）和腹侧中脑（VM）中尤为明显。我们研究了纯合H67D的C57BL6/129小鼠与野生型HFE小鼠的差异。使用免疫组织化学分析前3个月中脑腹侧（VM）的多巴胺能神经元和腰脊髓（LSC）的运动神经元群体成熟情况。使用免疫印迹法测量蛋白质羰基含量和氧化磷酸化复合物的表达。使用海马实验分析从腰脊髓和腹侧中脑分离的线粒体的代谢情况。最后，对这些区域内与神经退行性变相关的基因进行了纳米串转录组分析。与野生型小鼠相比，我们发现腰脊髓中运动神经元的活力没有差异，但H67D小鼠的多巴胺能神经元在3月龄前出现显著下降。H67D小鼠的两个区域氧化磷酸化复合物表达均发生改变，表明存在应激适应。与野生型相比，H67D小鼠两个区域的线粒体均表现出代谢差异。H67D小鼠这些区域的转录差异与细胞结构和黏附以及细胞信号传导有关。总体而言，我们发现腰脊髓和腹侧中脑在适应由H67D HFE基因变体诱导的铁相关应激时经历了显著且不同的代谢和转录变化。
