School of Biomedicine, University of Adelaide, Adelaide, SA 5005, Australia.
Biosci Rep. 2024 Mar 29;44(3). doi: 10.1042/BSR20231725.
In addition to aquaporin (AQP) classes AQP1, AQP4 and AQP9 known to be expressed in mammalian brain, our recent transcriptomic analyses identified AQP0 and AQP11 in human cortex and hippocampus at levels correlated with age and Alzheimer's disease (AD) status; however, protein localization remained unknown. Roles of AQP0 and AQP11 in transporting hydrogen peroxide (H2O2) in lens and kidney prompted our hypothesis that up-regulation in brain might similarly be protective. Established cell lines for astroglia (1321N1) and neurons (SHSY5Y, differentiated with retinoic acid) were used to monitor changes in transcript levels for human AQPs (AQP0 to AQP12) in response to inflammation (simulated with 10-100 ng/ml lipopolysaccharide [LPS], 24 h), and hypoxia (5 min N2, followed by 0 to 24 h normoxia). AQP transcripts up-regulated in both 1321N1 and SHSY5Y included AQP0, AQP1 and AQP11. Immunocytochemistry in 1321N1 cells confirmed protein expression for AQP0 and AQP11 in plasma membrane and endoplasmic reticulum; AQP11 increased 10-fold after LPS and AQP0 increased 0.3-fold. In SHSY5Y cells, AQP0 expression increased 0.2-fold after 24 h LPS; AQP11 showed no appreciable change. Proposed peroxiporin roles were tested using melondialdehyde (MDA) assays to quantify lipid peroxidation levels after brief H2O2. Boosting peroxiporin expression by LPS pretreatment lowered subsequent H2O2-induced MDA responses (∼50%) compared with controls; conversely small interfering RNA knockdown of AQP0 in 1321N1 increased lipid peroxidation (∼17%) after H2O2, with a similar trend for AQP11 siRNA. Interventions that increase native brain peroxiporin activity are promising as new approaches to mitigate damage caused by aging and neurodegeneration.
除了已知在哺乳动物大脑中表达的水通道蛋白 (AQP) 家族 AQP1、AQP4 和 AQP9 外，我们最近的转录组分析还在人类大脑的皮质和海马体中鉴定到 AQP0 和 AQP11，其水平与年龄和阿尔茨海默病 (AD) 状态相关；然而，其蛋白定位仍不清楚。AQP0 和 AQP11 在晶状体和肾脏中运输过氧化氢 (H2O2) 的作用促使我们提出假设，即大脑中的上调可能同样具有保护作用。我们使用已建立的星形胶质细胞（1321N1）和神经元（用视黄酸分化的 SHSY5Y）细胞系来监测人类 AQP（AQP0 至 AQP12）的转录水平在炎症（用 10-100ng/ml 脂多糖 [LPS] 模拟，24 小时）和缺氧（5 分钟氮气，随后 0 至 24 小时常氧）下的变化。在 1321N1 和 SHSY5Y 中上调的 AQP 转录物包括 AQP0、AQP1 和 AQP11。1321N1 细胞中的免疫细胞化学证实了 AQP0 和 AQP11 在质膜和内质网中的蛋白表达；LPS 后 AQP11 增加了 10 倍，AQP0 增加了 0.3 倍。在 SHSY5Y 细胞中，LPS 后 24 小时 AQP0 表达增加了 0.2 倍；AQP11 没有明显变化。使用丙二醛 (MDA) 测定法来定量短暂 H2O2 后的脂质过氧化水平，测试了拟肽孔蛋白的作用。与对照相比，LPS 预处理增加过氧化物孔蛋白表达可降低随后 H2O2 诱导的 MDA 反应（约 50%）；相反，在 1321N1 中用小干扰 RNA 敲低 AQP0 可使 H2O2 后脂质过氧化（约 17%）增加，AQP11 siRNA 也有类似趋势。增加内源性脑过氧化物孔蛋白活性的干预措施是有希望的，作为减轻衰老和神经退行性变引起的损伤的新方法。
