Ee Sze-Min, Lo Yew-Long, Shui Guanghou, Wenk Markus R, Shin Eun-Joo, Kim Hyoung-Chun, Ong Wei-Yi
Department of Anatomy, National University of Singapore, Singapore, 119260, Singapore.
Mol Neurobiol. 2014 Aug;50(1):60-75. doi: 10.1007/s12035-014-8635-7. Epub 2014 Jan 25.
Phospholipases A(2) (PLA(2)) catalyze the hydrolysis of membrane phospholipids to produce free fatty acids and lysophospholipids, which have important functions in cell signaling. The present study elucidated differential expression of PLA(2) isoforms in the rat cortex by quantitative reverse transcription PCR and demonstrated that sPLA(2)-XIIA had greater messenger RNA expression than iPLA(2)-VI or cPLA(2)-IVA in different brain regions, or compared to other sPLA(2) isoforms in the prefrontal cortex (PFC) and hippocampus. Western blots identified a 24-kDa band in different regions of the adult brain, and high levels of sPLA(2)-XIIA protein expression were detected in the PFC, striatum, and thalamus. Electron microscopy showed that sPLA(2)-XIIA is present in axon terminals and dendrites. Injection of antisense oligonucleotide to sPLA(2)-XIIA in the PFC and lipidomic analysis showed increase in phospholipid but decrease in lysophospholipid species consistent with decreased catalytic activity of the enzyme, changes in arachidonic acid release, and alterations in sphingolipids. sPLA(2)-XIIA knockdown also resulted in shorter latency timings in the passive avoidance test, and higher number of errors in the attention set-shifting task, indicating deficits in working memory and attention. Together, the results show an important role of sPLA(2)-XIIA in lipid metabolism, prefrontal cortical function, and cognition.
磷脂酶A(2)（PLA(2)）催化膜磷脂水解，产生游离脂肪酸和溶血磷脂，它们在细胞信号传导中具有重要功能。本研究通过定量逆转录PCR阐明了大鼠皮层中PLA(2)亚型的差异表达，并证明在不同脑区，sPLA(2)-XIIA的信使核糖核酸表达高于iPLA(2)-VI或cPLA(2)-IVA，与前额叶皮层（PFC）和海马体中的其他sPLA(2)亚型相比也是如此。蛋白质免疫印迹法在成年大脑的不同区域鉴定出一条24 kDa的条带，并且在PFC、纹状体和丘脑中检测到高水平的sPLA(2)-XIIA蛋白表达。电子显微镜显示sPLA(2)-XIIA存在于轴突终末和树突中。向PFC注射针对sPLA(2)-XIIA的反义寡核苷酸并进行脂质组学分析，结果显示磷脂增加但溶血磷脂种类减少，这与该酶催化活性降低、花生四烯酸释放变化以及鞘脂改变一致。sPLA(2)-XIIA基因敲低还导致被动回避试验中的潜伏期缩短，以及注意力转换任务中的错误数量增加，表明工作记忆和注意力存在缺陷。总之，这些结果表明sPLA(2)-XIIA在脂质代谢、前额叶皮层功能和认知中起重要作用。
