Regulation of Spermine Oxidase through Hypoxia-Inducible Factor-1α Signaling in Retinal Glial Cells under Hypoxic Conditions
Regulation of Spermine Oxidase through Hypoxia-Inducible Factor-1α Signaling in Retinal Glial Cells under Hypoxic Conditions
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DOI：
10.1167/iovs.61.6.52
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发表时间：
2020-06-01
影响因子：
4.4
通讯作者：
Ishida, Susumu
中科院分区：
文献类型：
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作者：
Wu, Di;Noda, Kousuke;Ishida, Susumu
目的.丙烯醛是一种高度反应性的不饱和醛，已知可促进神经胶质细胞迁移，这是糖尿病视网膜病变的病理标志之一。然而，视网膜神经胶质细胞中丙烯醛生成的细胞机制仍然是难以捉摸的。本研究探讨了精胺氧化酶（SMOX）在缺氧条件下视网膜神经胶质细胞中的作用及其调节。SMOX的免疫荧光染色使用从增殖性糖尿病视网膜病变患者获得的纤维血管组织切片进行。在常氧或缺氧条件下，分析大鼠视网膜Muller细胞系5（TR-MUL 5）细胞中多胺氧化酶（包括SMOX）的表达水平。使用荧光素酶测定来评估Smox在TR-MUL 5细胞中的转录活性。测量丙烯醛缀合蛋白、N-α-（3-甲酰基-3，4-脱氢哌啶子基）赖氨酸加合物（FDP-Lys）和过氧化氢的水平。SMOX定位于纤维血管组织的神经胶质细胞中。缺氧诱导TR-MUL 5细胞中SMOX的产生，这是通过沉默缺氧诱导因子-1 α（HIF 1a）而不是HIF 2a来抑制的。Smox的转录活性通过与Smox启动子区的缺氧反应元件2、3和4位点结合的HIF-1来调节。缺氧条件下TR-MUL 5细胞内FDP-赖氨酸和过氧化氢的生成增加，SMOX抑制剂MDL 72527可抑制FDP-赖氨酸和过氧化氢的生成。目前的数据表明，缺氧调节SMOX的产生，其在缺氧条件下通过Muller神经胶质细胞中的HIF-1 α信号传导在氧化应激诱导剂的产生中起作用。
PURPOSE. Acrolein, a highly reactive unsaturated aldehyde, is known to facilitate glial cell migration, one of the pathological hallmarks in diabetic retinopathy. However, cellular mechanisms of acrolein generation in retinal glial cells remains elusive. In the present study, we investigated the role and regulation of spermine oxidase (SMOX), one of the enzymes related to acrolein generation, in retinal glial cells under hypoxic condition.METHODS. Immunofluorescence staining for SMOX was performed using sections of fibrovascular tissues obtained from patients with proliferative diabetic retinopathy. Expression levels of polyamine oxidation enzymes including SMOX were analyzed in rat retinal Muller cell line 5 (TR-MUL5) cells under either normoxic or hypoxic conditions. The transcriptional activity of Smox in TR-MUL5 cells was evaluated using the luciferase assay. Levels of acrolein-conjugated protein, N-epsilon-(3-formyl-3,4-dehydropiperidino) lysine adduct (FDP-Lys), and hydrogen peroxide were measured.RESULTS. SMOX was localized in glial cells in fibrovascular tissues. Hypoxia induced SMOX production in TR-MUL5 cells, which was suppressed by silencing of hypoxia-inducible factor-1 alpha (Hif1a), but not Hif2a. Transcriptional activity of Smox was regulated through HIF-1 binding to hypoxia response elements 2, 3, and 4 sites in the promoter region of Smox. Generation of FDP-Lys and hydrogen peroxide increased in TR-MUL5 cells under hypoxic condition, which was abrogated by SMOX inhibitor MDL72527.CONCLUSIONS. The current data demonstrated that hypoxia regulates production of SMOX, which plays a role in the generation of oxidative stress inducers, through HIF-1 alpha signaling in Muller glial cells under hypoxic condition.