Lee Youn Ju, Choi So-Young, Yang Jae-Ho
Department of Pharmacology/Toxicology, School of Medicine, Catholic University of Daegu, Daegu, Republic of Korea.
Department of Pharmacology/Toxicology, School of Medicine, Catholic University of Daegu, Daegu, Republic of Korea.
Chemosphere. 2016 Apr;149:1-7. doi: 10.1016/j.chemosphere.2016.01.073. Epub 2016 Jan 27.
Perfluorohexanesulfonate (PFHxS), one of the major perfluoroalkyl compounds (PFCs), has been used in a variety of industrial and consumer applications and detected in serum in the general population. This raised a concern over its possible detrimental health effects, including neurotoxic effects. We have previously shown that PFHxS induced neuronal apoptosis via the NMDA receptor-mediated extracellular signal-regulated kinase (ERK) pathway. Recently, it has been reported that AMP-activated protein kinase (AMPK) acts as a key signal molecule in neuronal excitotoxicity as well as providing a neuroprotective function. In the present study, we have examined the involvement of AMPK in PFHxS-induced neuronal apoptosis using neuronal differentiated PC12 cells. PFHxS induced significant increases in intracellular [Ca(2+)] via the NMDA receptor and the L-type voltage-gated calcium channel (L-VGCC). The inhibition of Ca(2+) loading by the NMDA receptor antagonist, MK801 and the L-VGCC blockers, nifedipine and diltiazem significantly reduced PFHxS-induced apoptosis. PFHxS induced sustained activation of AMPK and the inhibition of AMPK activation by compound C and AMPK siRNA significantly reduced PFHxS-induced caspase-3 activity. These results indicate the pro-apoptotic role of AMPK. The activation of AMPK was attenuated by MK801, nifedipine and diltiazem. However, the activation of AMPK was not affected by the ERK inhibitor, PD98059. Likewise, ERK activation was not affected by compound C but was substantially reduced by MK801, nifedipine or diltiazem. This suggests that the activation of AMPK and ERK is regulated by intracellular Ca(2+) loading in distinct pathways. Taken together, PFHxS-induced neuronal apoptosis is mediated by AMPK and ERK pathways, which are distinctly regulated by increased intracellular Ca(2+) via the NMDA receptor and L-VGCC.
全氟己烷磺酸（PFHxS）是主要的全氟烷基化合物（PFCs）之一，已被用于各种工业和消费应用中，并在普通人群的血清中被检测到。这引发了人们对其可能的有害健康影响的担忧，包括神经毒性作用。我们之前已经表明，PFHxS通过N-甲基-D-天冬氨酸（NMDA）受体介导的细胞外信号调节激酶（ERK）途径诱导神经元凋亡。最近，有报道称，AMP激活的蛋白激酶（AMPK）在神经元兴奋性毒性中起关键信号分子的作用，并具有神经保护功能。在本研究中，我们使用神经元分化的PC12细胞研究了AMPK在PFHxS诱导的神经元凋亡中的作用。PFHxS通过NMDA受体和L型电压门控钙通道（L-VGCC）诱导细胞内[Ca(2+)]显著增加。NMDA受体拮抗剂MK801以及L-VGCC阻滞剂硝苯地平和地尔硫卓对Ca(2+)内流的抑制作用显著降低了PFHxS诱导的凋亡。PFHxS诱导AMPK持续激活，化合物C和AMPK小干扰RNA（siRNA）对AMPK激活的抑制作用显著降低了PFHxS诱导的半胱天冬酶-3活性。这些结果表明了AMPK的促凋亡作用。MK801、硝苯地平和地尔硫卓减弱了AMPK的激活。然而，ERK抑制剂PD98059对AMPK的激活没有影响。同样，化合物C对ERK激活没有影响，但MK801、硝苯地平或地尔硫卓可使其显著降低。这表明AMPK和ERK的激活在不同途径中受细胞内Ca(2+)内流的调节。综上所述，PFHxS诱导的神经元凋亡是由AMPK和ERK途径介导的，这两条途径分别通过NMDA受体和L-VGCC导致细胞内Ca(2+)增加而受到不同调节。
