Department of Integrative Bioscience and Biotechnology, Sejong University, Seoul, 05006, Republic of Korea.
Cell Death Dis. 2024 Nov 13;15(11):823. doi: 10.1038/s41419-024-07192-6.
In the context of acute brain injuries, where zinc neurotoxicity and oxidative stress are acknowledged contributors to neuronal damage, we investigated the pivotal role of lysosomes as a potential protective mechanism. Our research commenced with an exploration of epidermal growth factor (EGF) and its impact on lysosomal dynamics, particularly its neuroprotective potential against zinc-induced cytotoxicity. Using primary mouse cerebrocortical cultures, we observed the rapid induction of EGFR endocytosis triggered by EGF, resulting in a transient increase in lysosomal vesicles. Furthermore, EGF stimulated lysosomal biogenesis, evident through elevated expression of lysosomal-associated membrane protein 1 (LAMP-1) and the induction and activation of prominent lysosomal proteases, particularly cathepsin B (CTSB). This process of EGFR endocytosis was found to promote lysosomal augmentation, thus conferring protection against zinc-induced lysosomal membrane permeabilization (LMP) and subsequent neuronal death. Notably, the neuroprotective effects and lysosomal enhancement induced by EGF were almost completely reversed by the inhibition of clathrin-mediated and caveolin-mediated endocytosis pathways, along with the disruption of retrograde trafficking. Furthermore, tyrosine kinase inhibition of EGFR nullified EGFR endocytosis, resulting in the abrogation of EGF-induced lysosomal upregulation and neuroprotection. An intriguing aspect of our study is the successful replication of EGF's neuroprotective effects through the overexpression of LAMP-1, which significantly reduced zinc-induced LMP and cell death, demonstrated in both primary mouse cerebrocortical neuronal cultures and human embryonic kidney (HEK) cells. Our research extended beyond zinc-induced neurotoxicity, as we observed EGF's protective effects against other oxidative stressors linked to intracellular zinc release, including hydrogen peroxide (HO) and 1-methyl-4-phenylpyridinium ion (MPP). Collectively, our findings unveil the intricate interplay between EGF-triggered EGFR endocytosis, lysosomal upregulation, an increase in the regulatory capacity for zinc homeostasis, and the subsequent alleviation of zinc-induced neurotoxicity. These results present promising avenues for therapeutic interventions to enhance neuroprotection by targeting lysosomal augmentation.
在急性脑损伤的背景下，锌神经毒性和氧化应激被认为是神经元损伤的促成因素，我们研究了溶酶体作为一种潜在保护机制的关键作用。我们的研究始于探索表皮生长因子 (EGF) 及其对溶酶体动态的影响，特别是其对锌诱导细胞毒性的神经保护潜力。使用原代小鼠大脑皮质培养物，我们观察到 EGF 触发的 EGFR 内吞作用的快速诱导，导致溶酶体小泡的短暂增加。此外，EGF 刺激溶酶体发生，这表现在溶酶体相关膜蛋白 1 (LAMP-1) 的表达升高以及主要溶酶体蛋白酶，特别是组织蛋白酶 B (CTSB) 的诱导和激活。发现这种 EGFR 内吞作用过程促进了溶酶体的扩增，从而对锌诱导的溶酶体膜通透性 (LMP) 和随后的神经元死亡提供保护。值得注意的是，EGF 诱导的神经保护作用和溶酶体增强作用几乎完全被氯丙嗪介导和 caveolin 介导的内吞作用途径的抑制以及逆行运输的破坏所逆转。此外，EGFR 的酪氨酸激酶抑制消除了 EGFR 的内吞作用，导致 EGF 诱导的溶酶体上调和神经保护作用的丧失。我们研究的一个有趣方面是通过过表达 LAMP-1 成功复制了 EGF 的神经保护作用，这显著减少了锌诱导的 LMP 和细胞死亡，这在原代小鼠大脑皮质神经元培养物和人胚肾 (HEK) 细胞中都得到了证明。我们的研究不仅限于锌诱导的神经毒性，因为我们观察到 EGF 对其他与细胞内锌释放有关的氧化应激物（包括过氧化氢 (HO) 和 1-甲基-4-苯基吡啶离子 (MPP)) 的保护作用。总的来说，我们的研究结果揭示了 EGF 触发的 EGFR 内吞作用、溶酶体上调、锌动态平衡调节能力增加以及随后减轻锌诱导的神经毒性之间的复杂相互作用。这些结果为通过靶向溶酶体扩增来增强神经保护的治疗干预提供了有希望的途径。
