Gerstner Jason R, Bremer Quentin Z, Vander Heyden William M, Lavaute Timothy M, Yin Jerry C, Landry Charles F
Neuroscience Training Program, University of Wisconsin-Madison, Madison, Wisconsin, USA.
PLoS One. 2008 Feb 20;3(2):e1631. doi: 10.1371/journal.pone.0001631.
Brain fatty acid binding protein (Fabp7), which is important in early nervous system development, is expressed in astrocytes and neuronal cell precursors in mature brain. We report here that levels of Fabp7 mRNA in adult murine brain change over a 24 hour period. Unlike Fabp5, a fatty acid binding protein that is expressed widely in various cell types within brain, RNA analysis revealed that Fabp7 mRNA levels were elevated during the light period and lower during dark in brain regions involved in sleep and activity mechanisms. This pattern of Fabp7 mRNA expression was confirmed using in situ hybridization and found to occur throughout the entire brain. Changes in the intracellular distribution of Fabp7 mRNA were also evident over a 24 hour period. Diurnal changes in Fabp7, however, were not found in postnatal day 6 brain, when astrocytes are not yet mature. In contrast, granule cell precursors of the subgranular zone of adult hippocampus did undergo diurnal changes in Fabp7 expression. These changes paralleled oscillations in Fabp7 mRNA throughout the brain suggesting that cell-coordinated signals likely control brain-wide Fabp7 mRNA expression. Immunoblots revealed that Fabp7 protein levels also underwent diurnal changes in abundance, with peak levels occurring in the dark period. Of clock or clock-regulated genes, the synchronized, global cycling pattern of Fabp7 expression is unique and implicates glial cells in the response or modulation of activity and/or circadian rhythms.
脑脂肪酸结合蛋白（Fabp7）在早期神经系统发育中起重要作用，在成熟大脑的星形胶质细胞和神经元细胞前体中表达。我们在此报告，成年鼠脑中Fabp7 mRNA的水平在24小时内会发生变化。与在脑内各种细胞类型中广泛表达的脂肪酸结合蛋白Fabp5不同，RNA分析显示，在参与睡眠和活动机制的脑区中，Fabp7 mRNA水平在光照期升高，在黑暗期降低。这种Fabp7 mRNA表达模式通过原位杂交得到证实，并发现其在整个大脑中都存在。Fabp7 mRNA的细胞内分布在24小时内也有明显变化。然而，在出生后第6天的脑中未发现Fabp7的昼夜变化，此时星形胶质细胞尚未成熟。相比之下，成年海马体颗粒下区的颗粒细胞前体确实经历了Fabp7表达的昼夜变化。这些变化与整个大脑中Fabp7 mRNA的振荡平行，表明细胞协调信号可能控制全脑的Fabp7 mRNA表达。免疫印迹显示，Fabp7蛋白水平在丰度上也经历了昼夜变化，峰值出现在黑暗期。在时钟或时钟调节基因中，Fabp7表达的同步全局循环模式是独特的，这表明神经胶质细胞参与了活动和/或昼夜节律的反应或调节。
