Relevance of OPA-1 in the manganese- induced mitochondrial apoptotic pathway.

ALAIMO, A.;; GOROJOD R.; SAPIENZA C; KOTLER M.L.

Huerta Grande, Provincia de Córdoba, Argentina

Congreso; I Reunion Conjunta de Neurociencias (IRCN); 2009

Sociedad Argentina de Investigación en Neurociencias

Chronic manganese (Mn) exposure produces a neurological disorder known as Manganism. The astrocytic uptake of Mn is crucial in the development of this pathology. In previous studies, we demonstrated that Mn 750µM induces extrinsic apoptotic pathway by the increase of Fas-L levels and Caspases 8, 3/7 activation. In this work, we found that Mn treated glioma C6 cells behave as type II cells involving Bid total cleavage and activation, a Caspase 8 substrate that establishes a cross talk between the extrinsic and intrinsic pathways. Mitochondria are dynamic organelles, in constant fusion and fission leading to the formation of a mitochondrial network (MN). During apoptosis there is an impair fusion resulting in mitochondrial fragmentation. Using fluorescence microscopy and Mitotracker Red, we determined an increase in fission events, evidenced by the loss of MN. OPA-1 is a mitochondrial inner membrane protein involved in fusion and maintenance of the cristae structure. Its cleavage leads to MN fragmentation and apoptosis increase. Using WB analysis we found that Mn produces OPA-1 cleavage by the appearance of a lower MW band (71kDa) in comparison with the doublet  present in control (107/94 kDa). Moreover, OPA-1 processing diminished (90%) by the use of Caspase 8 inhibitor (10µM).This confirms the existent link between the apoptotic pathways mentioned above. Our model could serve as a good tool for investigations aimed to elucidating the role of apoptosis in manganism.