The protein levels of TLS (the most highly expressed gene of the SUMO pathway) as well as the transcription factors CRX and NR2E3, which showed a transcriptional activation after light exposition by qRT-PCR, were analyzed (Fig. 5A).
SAE1 is known to act as a heterodimer together with SAE2, and the induction of Sae1 observed after light exposition might reflect a different regulation for these two genes.
Similarly, Cbx4 and Desi1 (pattern II) had a constant increase of expression from condition 1 to 4. The retinal transcription factor Nr2e3 (pattern III) showed a sharp peak in response to light exposition (condition 2) that steadily decreased to the initial levels (condition 4 and 1).
Our randomized cross-over study aimed at analyzing the effects of light exposition with the use of Luminette® in a hospital department without access to natural light.
One possible explanation for these results would be that sumoylation as a posttranslational modification could be regulating (or regulated by) the response to light exposition.
These artificial illuminations changed our way of life altering the natural LD cycle and therefore desynchronizing the biological rhythms, and inducing behaviors of longer time of light exposition with possible consequences in retinal health.
For that reason, we will test our suggestions on a database, which is dedicated to illumination problems (CMU-PIE: 1386 images of 66 faces under 21 different illuminations [50]) and on an other one representing different faces with several expressions taken in different backgrounds (BIOID: 1521 images [51]) under variable light exposition (see Figure 9).
Besides allowing for intermittent monitoring of the procedure after all steps, visual examination ensures brief UV and visible light exposition times, thus reducing bleaching and unspecific chromogen deposition.
As the analyzed TFs are direct transcriptional regulators of downstream target genes, the differences in expression due to light exposition might be relevant.
The process of proteasomal proteolysis was initially described in the rat pineal as responsible for the rapid decrease in melatonin secretion in response to light exposition [ 19].
In order to distinguish differences in gene expression due to direct light exposition from those generated by circadian rhythmicity, we compared retinas obtained at the same time of the day, after 1.5 h of light exposition (condition 2) compared to the retinas obtained in sibling mice kept during all this time in the dark after the night cycle (condition 1).
