Arylalkylamine N-acetyltransferase: ?Nuclear translocation and potential role in response to blue light in retinal neuron cells?

RIOS, MAXIMILIANO N.; MARCHESE, NATALIA A.; GUIDO, MARIO E.

Congreso; ARVO 2020; 2020

Association for Research in Vision and Ophthalmology

Purpose : The vertebrate retina is a photosensitive organ, and the exposure to lights emitting diode (LEDs) is becoming more common in everyday life, blue light (BL) is the mainly component of LEDs and prolonged exposition to BL causes retinal damage and circadian rhythm disruption. Aryalkylamine N-acetyltransferase (AANAT) is the key regulatory enzyme in melatonin synthesis. AANAT is present in the pineal gland, retina and other regions where is controlled by the molecular clock and light. In addition AANAT belong to GNAT-5 family together with histones acetyl transferases and its activity is regulated by phosporylation. Here we investigated the regulation of AANAT phosphorylatiom and histone 3 acetylation at lysine 27 (H3k27) in primary cultures of chicken embryonic retinal cells exposed to BL.Methods : Primary cultures were prepared from embryonic retinas at embryonic day (E) 8 and kept for 3-4 days and were divided in three groups: Dark, BL 1h and 1h post BL. Cultures were exposed to BL of 68 µW/cm2 for 1 h, then protein from nucleoplasm and cells were colected for the study. The AANAT phosphoryilation and histone 3 acetylation at lysine 27 (H3acK27) were studied by immunocytochemstry (ICC) and western blot (WB) in cultures and nuclear fractions.Results : Cultures exhibited BL induction of AANAT as compared with dark controls (D). Interestingly AANAT showed a localization change, from the cytoplasm to nucleus, increasing in BL, and remain elevated in darkness 1 h after BL exposure. Furthermore, high levels of the phosphorylated enzyme were detected after the BL treatment comparated with the D control, in nuclear fractions obtained from primary cultures together with a significant increase in H3k27 levels after BL treatmentConclusions : Results suggest that AANAT is a BL-induced enzyme in retinal neuron cells. And the BL exposure promotes the AANAT phosphorylation and nuclear importation togeteher changes in H3ac27, likely playing important roles in nuclear function.