García-Fernández José M, Alvarez-López Carmen, Cernuda-Cernuda Rafael
Department of Morphology and Cell Biology, University of Oviedo, 33071 Oviedo, Spain.
Neurosci Lett. 2007 May 23;419(1):55-8. doi: 10.1016/j.neulet.2007.03.054. Epub 2007 Mar 30.
The mammalian Period1 gene is rhythmically expressed and its proteins are found within the nucleus of the cells of the suprachiasmatic nuclei (SCN), the central circadian pacemaker in mammals; however, whether the target of the PER1 proteins is also the nucleus in the retinal peripheral clock cells is yet to be determined. Using an anti-PER1 protein antibody in Western blot analyses, we found three isoforms (75, 110 and 140kDa) in extracts of the SCN, as well as in other different parts of the brain, whereas just two isoforms (75 and 110kDa) were detected in the retinal extracts. We have observed that PER1 immunolabelling has a cytoplasmic location in many cells of the ganglion cell layer and in a few cells in the inner nuclear layer of the mouse retina. This cellular location was seen in any of the tissue samples taken at 4h intervals, either in the day/night cycle or in constant darkness, of both wild type and rd mice. Unlike this situation, PER1 isoforms were nuclear proteins in the SCN cells as well as in other parts of the brain of the same animals. No circadian changes were found for these clock proteins in the neural retina. These findings suggest that PER1 proteins play roles in the retina different from those established in the SCN.
哺乳动物的Period1基因呈节律性表达，其蛋白质存在于视交叉上核（SCN）细胞的细胞核内，视交叉上核是哺乳动物的中央昼夜节律起搏器；然而，PER1蛋白在视网膜外周生物钟细胞中的作用靶点是否也是细胞核，仍有待确定。在蛋白质印迹分析中使用抗PER1蛋白抗体，我们在视交叉上核提取物以及大脑的其他不同部位发现了三种异构体（75、110和140kDa），而在视网膜提取物中仅检测到两种异构体（75和110kDa）。我们观察到，在小鼠视网膜神经节细胞层的许多细胞以及内核层的少数细胞中，PER1免疫标记位于细胞质中。在野生型和rd小鼠的昼夜/夜间周期或持续黑暗中，每隔4小时采集的任何组织样本中均可见到这种细胞定位。与这种情况不同的是，在同一动物的视交叉上核细胞以及大脑的其他部位，PER1异构体是核蛋白。在神经视网膜中未发现这些生物钟蛋白的昼夜节律变化。这些发现表明，PER1蛋白在视网膜中的作用与在视交叉上核中确定的作用不同。
