Noguchi Noriko, Urano Yasuomi, Takabe Wakako, Saito Yoshiro
Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan.
Systems Life Sciences Laboratory, Department of Medical Life Systems, Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0394, Japan.
Free Radic Biol Med. 2015 Oct;87:366-72. doi: 10.1016/j.freeradbiomed.2015.06.036. Epub 2015 Jul 9.
24(S)-Hydroxycholesterol (24S-OHC), which is enzymatically produced in the brain, has been known to play an important role in maintaining cholesterol homeostasis in the brain and has been proposed as a possible biomarker of neurodegenerative disease. Recent studies have revealed diverse functions of 24S-OHC and gained increased attention. For example, 24S-OHC at sublethal concentrations has been found to induce an adaptive response via activation of the liver X receptor signaling pathway, thereby protecting neuronal cells against subsequent oxidative stress. It has also been found that physiological concentrations of 24S-OHC suppress amyloid-β production via downregulation of amyloid precursor protein trafficking in neuronal cells. On the other hand, high concentrations of 24S-OHC have been found to induce a type of nonapoptotic programmed cell death in neuronal cells expressing little caspase-8. Because neuronal cell death induced by 24S-OHC has been found to proceed by a unique mechanism, which is different from but in some ways similar to necroptosis-necroptosis being a type of programmed necrosis induced by tumor necrosis factor α-neuronal cell death induced by 24S-OHC has been called "necroptosis-like" cell death. 24S-OHC-induced cell death is dependent on the formation of 24S-OHC esters but not on oxidative stress. This review article discusses newly reported aspects of 24S-OHC in neuronal cell death and sheds light on the possible importance of controlling 24S-OHC levels in the brain for preventing neurodegenerative disease.
24(S)-羟基胆固醇(24S-OHC)是在大脑中通过酶促反应产生的,已知其在维持大脑胆固醇稳态中发挥重要作用,并被提议作为神经退行性疾病的一种可能生物标志物。最近的研究揭示了24S-OHC的多种功能,并受到了更多关注。例如,已发现亚致死浓度的24S-OHC通过激活肝X受体信号通路诱导适应性反应,从而保护神经元细胞免受随后的氧化应激。还发现生理浓度的24S-OHC通过下调神经元细胞中淀粉样前体蛋白的转运来抑制淀粉样β蛋白的产生。另一方面,已发现高浓度的24S-OHC在几乎不表达半胱天冬酶-8的神经元细胞中诱导一种非凋亡程序性细胞死亡。由于已发现24S-OHC诱导的神经元细胞死亡通过一种独特机制进行,该机制与坏死性凋亡不同但在某些方面相似——坏死性凋亡是由肿瘤坏死因子α诱导的一种程序性坏死——24S-OHC诱导的神经元细胞死亡被称为“类坏死性凋亡”细胞死亡。24S-OHC诱导的细胞死亡依赖于24S-OHC酯的形成,而不依赖于氧化应激。这篇综述文章讨论了24S-OHC在神经元细胞死亡方面新报道的内容,并阐明了控制大脑中24S-OHC水平对于预防神经退行性疾病可能具有的重要性。