Kaftan Öcal Gizem, Armagan Güliz
Biochemistry PhD Programme, Graduate School of Health Sciences, Ege University, Izmir 35100, Türkiye.
Department of Biochemistry, Faculty of Pharmacy, Ayfonkarahisar Health Sciences University, Afyonkarahisar 03218, Türkiye.
ACS Chem Neurosci. 2025 Apr 16;16(8):1500-1510. doi: 10.1021/acschemneuro.5c00029. Epub 2025 Mar 27.
Neuromelanin (NM) is an iron-rich, insoluble brown or black pigment that exhibits protective properties. However, its accumulation over time may render it a source of free radicals. In Parkinson's disease, dopaminergic neurons with the highest NM levels and increased iron content are preferentially vulnerable to degeneration. Considering NM's iron binding capacity and the critical role of iron in ferroptosis, we aimed to investigate the interplay between neuromelanin and ferroptosis in dopaminergic cells. We prepared two NM pigments: iron-free NM (ifNM) and iron-containing NM (FeNM) and, exposed to cells. After verifying NM accumulation, cell viability was assessed in the absence or presence of antioxidants (NAC (1 mM), Trolox (100 μM)) and specific inhibitors of cell death types. Ferroptosis-related parameters, including lipid peroxidation byproducts (4-HNE), lipid ROS, glutathione, intracellular iron, GPX4, and ACSL4, and cellular iron metabolism-related proteins (TfR1, ferroportin, ferritin, IREB2) were evaluated following ifNM and FeNM treatments, with or without Ferrostatin-1, Liproxstatin-1 and deferoxamine. Both NMs induced cell death via distinct mechanisms. Ferroptotic cell death by ifNM and FeNM was reversed by ferrostatin-1 and NAC ( < 0.05). Significant alterations in lipid peroxidation, GPX4 levels, and iron metabolism were observed independent of NM's iron composition ( < 0.05). Ferritin levels increased following ifNM treatment, reflecting an adaptive response to iron overload, while FeNM treatment led to ferritin depletion, possibly via ferritinophagy. Our findings reveal a distinct role of iron-rich and iron-free neuromelanin in modulating ferroptotic pathways, highlighting the potential of targeting neuromelanin-iron interactions as a therapeutic strategy to mitigate neuronal ferroptosis in Parkinson's disease.
神经黑色素（NM）是一种富含铁的不溶性棕色或黑色色素，具有保护特性。然而，随着时间的推移，其积累可能使其成为自由基的来源。在帕金森病中，神经黑色素水平最高且铁含量增加的多巴胺能神经元优先易发生变性。考虑到神经黑色素的铁结合能力以及铁在铁死亡中的关键作用，我们旨在研究多巴胺能细胞中神经黑色素与铁死亡之间的相互作用。我们制备了两种神经黑色素色素：无铁神经黑色素（ifNM）和含铁神经黑色素（FeNM），并将其暴露于细胞。在验证神经黑色素积累后，在不存在或存在抗氧化剂（NAC（1 mM）、Trolox（100 μM））和特定细胞死亡类型抑制剂的情况下评估细胞活力。在ifNM和FeNM处理后，无论是否使用铁死亡抑制剂Ferrostatin-1、Liproxstatin-1和去铁胺，评估铁死亡相关参数，包括脂质过氧化副产物（4-HNE）、脂质活性氧、谷胱甘肽、细胞内铁、GPX4和ACSL4，以及细胞铁代谢相关蛋白（TfR1、铁转运蛋白、铁蛋白、IREB2）。两种神经黑色素均通过不同机制诱导细胞死亡。ifNM和FeNM诱导的铁死亡性细胞死亡被铁死亡抑制剂Ferrostatin-1和NAC逆转（<0.05）。观察到脂质过氧化、GPX4水平和铁代谢的显著改变，与神经黑色素的铁组成无关（<0.05）。ifNM处理后铁蛋白水平升高，反映了对铁过载的适应性反应，而FeNM处理导致铁蛋白耗竭，可能是通过铁蛋白自噬。我们的研究结果揭示了富含铁和不含铁的神经黑色素在调节铁死亡途径中的独特作用，突出了靶向神经黑色素-铁相互作用作为减轻帕金森病神经元铁死亡的治疗策略的潜力。
