Neurobiology Sector, International School for Advanced Studies (SISSA), Trieste, Italy.
PLoS One. 2011;6(10):e26334. doi: 10.1371/journal.pone.0026334. Epub 2011 Oct 24.
Analysis with DNA-microrrays and real time PCR show that several genes involved in the thyroid hormone cascade, such as deiodinase 2 and 3 (Dio2 and Dio3) are differentially regulated by the circadian clock and by changes of the ambient light. The expression level of Dio2 in adult rats (2-3 months of age) kept continuously in darkness is modulated by the circadian clock and is up-regulated by 2 fold at midday. When the diurnal ambient light was on, the expression level of Dio2 increased by 4-8 fold and a consequent increase of the related protein was detected around the nuclei of retinal photoreceptors and of neurons in inner and outer nuclear layers. The expression level of Dio3 had a different temporal pattern and was down-regulated by diurnal light. Our results suggest that DIO2 and DIO3 have a role not only in the developing retina but also in the adult retina and are powerfully regulated by light. As the thyroid hormone is a ligand-inducible transcription factor controlling the expression of several target genes, the transcriptional activation of Dio2 could be a novel genomic component of light adaptation.
DNA 微阵列和实时 PCR 分析表明，甲状腺激素级联中的几个基因，如脱碘酶 2 和 3（Dio2 和 Dio3），受昼夜节律和环境光变化的差异调控。在持续处于黑暗环境中的成年大鼠（2-3 个月大）中，Dio2 的表达水平受昼夜节律调控，并在中午时上调 2 倍。当昼夜环境光开启时，Dio2 的表达水平增加 4-8 倍，并且在视网膜光感受器和内核层和外核层神经元的核周围检测到相关蛋白的相应增加。Dio3 的表达水平具有不同的时间模式，并且受到昼夜光的下调。我们的结果表明，DIO2 和 DIO3 不仅在发育中的视网膜中起作用，而且在成年视网膜中也起作用，并且受光的强烈调节。由于甲状腺激素是一种配体诱导转录因子，可控制几个靶基因的表达，因此 Dio2 的转录激活可能是光适应的一个新的基因组组成部分。
