Involvement of mitochondrial fission events in an experimental model of Manganism´s disease

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

San Diego, EEUU

Congreso; 40th Annual Meeting- Society for Neuroscience; 2010

Society for Neuroscience

Chronic exposure to manganese (Mn) results in extrapyramidal system neurotoxicity and the development of Parkinson´s disease-like disorder referred to as Manganism. Mn accumulation in astrocytic mitochondria is crucial in the establishment of this pathology. Mitochondria are dynamic organelles which exist as interconnected networks, maintained by a balance of constant occurring fission and fusion events, required for normal mitochondrial and cellular function. Evidence indicates that mitochondria undergo rapid and extensive fission during apoptosis. Being aware that a decline in mitochondrial function is described in neurodegenerative diseases, we study the Mn2+ induced-apoptotic pathways and its effects on mitochondrial dynamics in glioma C6 cells. In this report we demonstrated that 750ìM Mn2+ induced extrinsic apoptotic pathway via Fas-L induction and Caspase 8 activation. Mn2+ treated cells behave as type II cells implying total cleavage and activation of Bid. The involvement of apoptotic mitochondrial pathway was confirmed by activation of caspase 9 and disruption of mitochondrial membrane potential employing Mitotracker Red CMXRos. Using fluorescence microscopy and Mitotracker Red CMXRos, we observed an increase in fission events determined by the disruption of mitochondrial network (MN). OPA1 is a mitochondrial inner membrane protein that promotes the formation of an elongated MN and the maintenance of the cristae structure. Cleavage and disassembly of OPA-1 complexes leads to fragmentation of the MN and apoptosis. By WB analysis we found that Mn2+ produces OPA-1 cleavage with the appearance of a 71kDa band, which decreases (90%) in the presence of Caspase 8 inhibitor. Moreover, cells transfected with either WT or Q297V (disassembly-resistant mutant) OPA-1cDNA plasmids and treated with Mn2+ exhibited a recovery in cell viability (40%) and a decrease in the fission events. In summary, our findings demonstrate the involvement of mitochondrial fission/fusion machinery players in the Mn-induced apoptotic pathway in C6 cells. OPA-1 may represent a new drug target to antagonize the progression or triggering of Manganism.