Poly(ADP-ribose)polymerase (PARP) is involved in DNA break signal mechanisms in Trypanosoma cruzi

SALOMÉ VILCHEZ LARREA; GUILLERMO D. ALONSO; HÉCTOR N. TORRES; MIRTHA M. FLAWIÁ; SILVIA H. FERNÁNDEZ VILLAMIL

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión de la Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular; 2007

DNA damage signaling is crucial for the maintenance of genome integrity. In higher eukaryotes a NAD dependent signal transduction mechanism protects cells against the genome destabilizing effects of DNA strand breaks. Poly(ADP-ribose) polymerase has been implicated in this pathway. We demonstrated that the recombinant enzyme from Trypanosoma cruzi (TcPARP) is strongly activated in presence of nicked DNA and polymers of ADP-ribose are attached to PARP itself and to T. cruzi histones. According to this, PAR synthesized could dissociate histones from DNA granting the DNA repairing machinery access to damaged DNA. DNA damaging agents implicated in different repair mechanisms, such as H2O2, beta-lapachone, methyl methane sulfonate and UV radiations, were used to study PARP response. The results by using Western blot analysis with anti PAR antibodies showed that PAR synthesis was increased in the presence of these agents. However, when the damage induced led to cell death, the amount of PAR detected decreased. In vivo assays by indirect immunofluorescence confirmed the results obtained by western blot. We also tested the response in trypanosomes over-expressing PARP. These results are in agreement with the previous proposed mechanisms for PARP in DNA strand break signaling