Effects of organophosphates on protein phosphorylation and transcription activating factors in toad embryos

ANGUIANO O.L; MONTAGNA M; VENTURINO A; PECHEN DE D'ANGELO A.M.

Villa Carlos Paz

Congreso; XXXVIII Reunión Anual de la SAIB; 2002

SAIB

Pesticide actions on cellular development may be related to mo­lecular targets in signaling, transduction and genetic responses, involving receptors such as the aryl hydrocarbon receptor, protein kinase/phosphatase cascades and nuclear transcription factors in their toxicity. "Bufo arenarum" embryos were exposed up to 96 h to 20 mg/L malathion or 9 mglL azinphos melhyl to determine possible effects on the regulation of transcription factors using Elec­trophoretic gel Mobility Shift Assay (EMSA) and on protein phos­phorylating activity of extracts using 32P(gama)ATP, protein separation by SDS-PAGE and autoradiographic revealing. Malathion exposure produced no effects at first cleavage (4 h of exposure) whereas at late gastrulae (48 h) a significant increase in binding activity to AMPc Responsive Element (CRE) followed by its decrease (96 h) was detected. Azinphos methyl also caused an increase in CRE-binding activity but shifted to 96 h of treatment. In turn, API-binding transcription factors were downregulated by malathion treatment at 48 and 96 h. Both treatments caused a sig­nificant increase in protein phosphorylalion of a 24-kD band, and a reduction in 37-kD and 60-kD bands at 96 h. Malathion also in­creased protein phosphorylalion at 21 kD band. We have previ­ously demonstrated that both insecticides alter embryonic devel­opment in "B. arenarum". Our results suggest that these organophosphates may be acting through protein phosphorylation- dephosphorylation and transcription factor regulation to interfere with normal development. Alternatively, these effects may be part of a stress response and pesticide detoxifícation.