Homola Moran, Pfeffer Martina, Robson Simon C, Fischer Claudia, Zimmermann Herbert, Korf Horst-Werner
Institute of Anatomy II, Dr. Senckenbergisches Chronomedizinisches Institut (SCI), Goethe University, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, 3 Blackfan Circle, Boston, MA 02215, USA.
Cell Tissue Res. 2016 Jul;365(1):147-56. doi: 10.1007/s00441-016-2378-x. Epub 2016 Feb 26.
Ecto-5'-nucleotidase (eN) is the major extracellular adenosine-producing ecto-enzyme in mouse brain. Via the production of adenosine, eN participates in many physiological and pathological processes, such as wakefulness, inflammation, nociception and neuroprotection. The mechanisms regulating the expression of eN are therefore of considerable neurobiological and clinical interest. Having previously described a modulatory effect of melatonin in the regulation of eN mRNA levels, we decided to analyze the melatonin receptor subtype involved in the regulation of eN mRNA levels by comparing eN mRNA patterns in melatonin-proficient transgenic mice lacking either the melatonin receptor subtype 1 (MT1 KO) or both melatonin receptor subtypes (MT1 and MT2; MT1/2 KO) with the corresponding melatonin-proficient wild-type (WT) controls. By means of radioactive in situ hybridization, eN mRNA levels were found to be diminished in both MT1 and MT1/2 KO mice compared with WT controls suggesting stimulatory impacts of melatonin receptors on eN mRNA levels. Whereas eN mRNA levels increased during the day and peaked at night in WT and MT1 KO mice, eN mRNA levels at night were reduced and the peak was shifted toward day-time in double MT1/2 KO mice. These data suggest that the MT2 receptor subtype may play a role in the temporal regulation of eN mRNA availability. Notably, day-time locomotor activity was significantly higher in MT1/2 KO compared with WT mice. Our results suggest melatoninergic signaling as an interface between the purinergic system and the circadian system.
胞外5'-核苷酸酶（eN）是小鼠大脑中主要的产生细胞外腺苷的胞外酶。通过产生腺苷，eN参与许多生理和病理过程，如清醒、炎症、伤害感受和神经保护。因此，调节eN表达的机制具有相当大的神经生物学和临床研究价值。此前我们已经描述了褪黑素在调节eN mRNA水平方面的调节作用，我们决定通过比较缺乏褪黑素受体亚型1（MT1基因敲除）或同时缺乏两种褪黑素受体亚型（MT1和MT2；MT1/2基因敲除）的褪黑素功能正常的转基因小鼠与相应的褪黑素功能正常的野生型（WT）对照小鼠的eN mRNA模式，来分析参与调节eN mRNA水平的褪黑素受体亚型。通过放射性原位杂交发现，与WT对照相比，MT1和MT1/2基因敲除小鼠中的eN mRNA水平均降低，这表明褪黑素受体对eN mRNA水平有刺激作用。在WT和MT1基因敲除小鼠中，eN mRNA水平在白天升高并在夜间达到峰值，而在MT1/2基因敲除小鼠中，夜间eN mRNA水平降低且峰值向白天偏移。这些数据表明MT2受体亚型可能在eN mRNA可利用性的时间调节中发挥作用。值得注意的是，与WT小鼠相比，MT1/2基因敲除小鼠的白天运动活动明显更高。我们的结果表明褪黑素能信号传导是嘌呤能系统与昼夜节律系统之间的一个接口。
