Liu Jui-Ming, Liu Shing-Hwa, Fu Shih-Chang, Lai Wei-Cheng, Fang Kai-Min, Lin Ken-An, Ke Jun-An, Kuo Chun-Ying, Su Chin-Chuan, Chen Ya-Wen
Division of Urology, Department of Surgery, Taoyuan General Hospital, Ministry of Health and Welfare, Taoyuan 330, Taiwan; Department of Obstetrics and Gynecology, Tri-Service General Hospital, National Defense Medical Center, Taipei 114, Taiwan.
Institute of Toxicology, College of Medicine, National Taiwan University, Taipei 100, Taiwan.
Toxicology. 2025 Jan;510:154014. doi: 10.1016/j.tox.2024.154014. Epub 2024 Nov 23.
Tetrabromobisphenol A (TBBPA), a brominated flame retardant (BFR), has been implicated as the neurotoxic effects in mammalian. However, the exact mechanisms underlying TBBPA-induced neurotoxicity remain unclear. In the present study, Neuro-2a cells, a mouse neural crest-derived cell line, were used to examine the mechanism of TBBPA-induced neuronal cytotoxicity. TBBPA exposure caused alterations in cell viability and mitochondrial membrane potential (MMP) and induction of apoptotic events, such as increased apoptotic cell population and cleaved caspase-3, -7, -9, and poly (ADP-ribose) polymerase (PARP) protein expression). TBBPA exposure triggered CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) activation. Transfection with CHOP-specific small interfering RNA (siRNA) obviously prevented the expression of CHOP protein and markedly attenuated MMP loss, and caspase-3 and -7 activation in TBBPA-exposed Neuro-2a cells. In addition, TBBPA exposure significantly evoked the phosphorylation of c-Jun N-terminal kinase (JNK), extracellular-signal regulated kinase1/2 (ERK1/2), p38-mitogen-activated protein kinase (p38-MAPK), and AMP-activated protein kinase (AMPK)α proteins. Pretreatment of cells with pharmacological inhibitors of p38-MAPK (SB203580) and AMPK (compound C), but not inhibitors of JNK (SP600125) or ERK1/2 (PD98059), effectively prevented the increase in caspase-3 activity, MMP loss, and activated CHOP and cleaved caspase-3 and -7 protein expression in TBBPA-treated cells. Notably, transfection with either p38α-MAPK- or AMPKα1/2-specific siRNAs markedly attenuated the expression of CHOP, and cleaved caspase-3 and -7. Interestingly, transfection with each siRNA significantly reduced the TBBPA-induced phosphorylation of p38-MAPK and AMPKα proteins. Collectively, these findings suggest that CHOP activation-mediated mitochondria-dependent apoptosis contributes to TBBPA-induced neurotoxicity. An interdependent p38-MAPK and AMPKα signaling-regulated apoptotic pathway may provide new insights into the mechanism understanding TBBPA-elicited neurotoxicity.
四溴双酚A（TBBPA）是一种溴化阻燃剂（BFR），被认为对哺乳动物具有神经毒性作用。然而，TBBPA诱导神经毒性的确切机制仍不清楚。在本研究中，使用Neuro-2a细胞（一种源自小鼠神经嵴的细胞系）来研究TBBPA诱导神经元细胞毒性的机制。TBBPA暴露导致细胞活力和线粒体膜电位（MMP）发生改变，并诱导凋亡事件，如凋亡细胞数量增加以及半胱天冬酶-3、-7、-9和聚（ADP-核糖）聚合酶（PARP）蛋白表达的裂解。TBBPA暴露触发了CCAAT/增强子结合蛋白（C/EBP）同源蛋白（CHOP）的激活。用CHOP特异性小干扰RNA（siRNA）转染明显阻止了CHOP蛋白的表达，并显著减轻了TBBPA暴露的Neuro-2a细胞中的MMP损失以及半胱天冬酶-3和-7的激活。此外，TBBPA暴露显著诱导了c-Jun氨基末端激酶（JNK）、细胞外信号调节激酶1/2（ERK1/2）、p38丝裂原活化蛋白激酶（p38-MAPK）和AMP活化蛋白激酶（AMPK）α蛋白的磷酸化。用p38-MAPK（SB203580）和AMPK（化合物C）的药理抑制剂预处理细胞，但不用JNK（SP600125）或ERK1/2（PD98059）的抑制剂，有效地阻止了TBBPA处理细胞中半胱天冬酶-3活性的增加、MMP损失以及CHOP的激活和裂解的半胱天冬酶-3和-7蛋白表达。值得注意的是，用p38α-MAPK或AMPKα（1/2）特异性siRNAs转染显著减弱了CHOP以及裂解的半胱天冬酶-3和-7的表达。有趣的是，用每种siRNA转染显著降低了TBBPA诱导的p38-MAPK和AMPKα蛋白的磷酸化。总的来说，这些发现表明CHOP激活介导的线粒体依赖性凋亡促成了TBBPA诱导的神经毒性。相互依赖的p38-MAPK和AMPKα信号调节的凋亡途径可能为理解TBBPA引发的神经毒性机制提供新的见解。
