CHARACTERIZATION OF POLY(ADPR)RIBOSYLATION REACTION IN THE BRAIN OF ADULT ZEBRAFISH EXPOSED TO ALUMINUM

One of the first molecular responses to DNA damage is the activation of poly(ADP)ribosylation, a covalent and reversible post-translational modification of proteins, catalyzed by a family of enzymes known as poly(ADP-ribose)polymerases (PARPs). Nuclear PARPs play important roles in various cellular processes, including modulation of chromatin structure, transcription, replication, recombination, and DNA repair. These enzymes are considered the “sensors” of DNA damage because they are activated following damage to genomic material. Aluminum has toxic effects on a variety of organs, including the brain, and in light of our previous studies, we aimed to evaluate PARP expression and activity and poly(ADPR) content in homogenates of adult zebrafish brain, exposed to 11 mg/L of this metal for 10, 15, and 20 days. Western blotting analysis with anti-PARP antibody showed the presence of different enzyme isoforms having various molecular weights, but no significant alteration in their expression was observed in brain samples exposed to metal compared with the control. On the contrary, the data on PARP activity was significantly higher in samples exposed to Aluminum for 10 and 15 days, while it decreases at longer exposure times (20 days). This trend was also followed by the production of poly(ADPR). Our preliminary data lead us to hypothesize that DNA damage with consequent PARP activation and poly(ADPR) production occurs at short exposure times. At longer times of exposure, the reduction of PARP activity is necessary because it preserves the intracellular energy necessary to guarantee the survival of the fish.