Xie Siwen, Yin Meng, Xiang Mengting, Shao Litao, Zhang Nan, Shi Liang, Zhang Juan, Yu Gongchang
Shandong Academy of Occupational Health and Occupational Medicine, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong, China.
Neck-Shoulder and Lumbocrural Pain Hospital of Shandong First Medical University, Shandong First Medical University & Shandong Academy of Medical Sciences, Jinan, Shandong, China.
Biol Trace Elem Res. 2024 Dec 6. doi: 10.1007/s12011-024-04427-7.
Lead (Pb) is the most common contaminant of heavy metals and is widely present in the environment. Destruction of bone structure, malformation of bone development, and loss of bone mass are important pathological features of lead-exposed individuals. However, the exact molecular mechanisms associated with lead exposure and osteogenic injury are still not fully understood. MC3T3-E1 mouse embryonic osteoblast is a cell line widely used in osteoblast cytology. It can differentiate into mature osteoblasts and express bone-specific genes in cell culture. The doses of 1, 2, and 4 mM Pb were adopted to study the toxicity of Pb on MC3T3-E1 proliferation and differentiation. In this study, the results show that Pb increases the expression of apoptosis-related proteins, including PARP1, cleaved caspase-3, Bax, and cleaved caspase-9. More importantly, Pb activated endoplasmic reticulum stress and oxidative stress, as evident by elevated PERK/ATF4/CHOP and ROS/NRF2 signaling pathway. Pb induced ROS production in MC3T3-E1 cells through endoplasmic reticulum stress and produced a lethal effect. NAC mitigated these effects. Endoplasmic reticulum stress inhibitor 4-PBA can block the ER stress pathway, reduce ROS production, and enhance cell viability. In addition, studies have shown that ERO1 activation in the ER stress pathway is responsible for inducing ROS production. ROS produced by the mitochondrial pathway also aggravates ER stress. This study suggests that Pb induces MC3T3-E1 cell apoptosis by inducing PERK-mediated ER stress and NRF2-mediated oxidative stress via mutual enhancement, which may be an important mechanism leading to skeletal toxicity.
铅（Pb）是最常见的重金属污染物，广泛存在于环境中。骨结构破坏、骨骼发育畸形和骨量丢失是铅暴露个体的重要病理特征。然而，与铅暴露和骨生成损伤相关的确切分子机制仍未完全明确。MC3T3-E1小鼠胚胎成骨细胞是成骨细胞细胞学中广泛使用的细胞系。它在细胞培养中可分化为成熟的成骨细胞并表达骨特异性基因。采用1、2和4 mM的铅剂量来研究铅对MC3T3-E1增殖和分化的毒性。在本研究中，结果表明铅增加了凋亡相关蛋白的表达，包括PARP1、裂解的caspase-3、Bax和裂解的caspase-9。更重要的是，铅激活了内质网应激和氧化应激，这从PERK/ATF4/CHOP和ROS/NRF2信号通路的升高可以明显看出。铅通过内质网应激在MC3T3-E1细胞中诱导ROS产生并产生致死效应。NAC减轻了这些效应。内质网应激抑制剂4-PBA可阻断内质网应激途径，减少ROS产生并提高细胞活力。此外，研究表明内质网应激途径中的ERO1激活负责诱导ROS产生。线粒体途径产生的ROS也会加剧内质网应激。本研究表明，铅通过相互增强诱导PERK介导的内质网应激和NRF2介导的氧化应激来诱导MC3T3-E1细胞凋亡，这可能是导致骨骼毒性的重要机制。
