Objective To determine if DNA excision repair enzymes oxoguanine glycosylase 1 （OGG1） and xeroderma pigmentosum group F protein （XPF） are involved in the pathogenesis of Parkinson＇s disease （PD） in a cell model. Methods PC12 cells were treated with 1-Methyl-4-phenylpyridine ion （MPP＋） for various periods of time to induce oxidative DNA damage. MTT assay was used to determine cell viability. Immunocytochemistry with antibody against 8-hydroxy-2＇- deoxyguanosine （8-oxodG） was used to evaluate oxidative DNA damage. Immunoblotting was used to detect the protein levels of OGG1 and XPF. Results MPP＋ treatment （1 mmol/L） for 18 h and 24 h reduced cell viability to 78.6% and 70.3% of the control, respectively, in a time-dependent way. MPP＋ increased the immunoreactivity of 8-oxodG in the cytoplasm at 3 h and in the nucleus at 24 h of treatment. With the treatment of MPP＋, the expression of OGG1 was significantly increased at 1 h, reaching a peak at 3 h, and then it was decreased at 24 h, as compared to that with vehicle treatment. The same effect was exerted on XPF level, except that the XPF level reached a peak at 18 h of MPP＋ treatment. Moreover, the maximally-increased protein level of OGG1 by MPP＋ was approximately 2-fold higher than that of XPF. Conclusion MPP＋ treatment could time- dependently induce increases in OGG1 and XPF expressions in PC12 cells. Also, this study indicates that the base and nucleotide excision repair pathways may be compensatorily activated in the early stage of pathogenesis in the cells after MPP＋ treatment.
Objective It has been reported that B-cell lymphoma 2 （Bcl-2） enhances neurogenesis as well as supporting axonal growth after injury. In the present study, we investigated whether Bcl-2 overexpression plays a role in the formation of newborn striatonigral projection neurons in the adult rat brain after transient middle cerebral artery occlusion （MCAO）. Methods We infused human Bcl-2-expressing plasmid （pBcl-2） into the lateral ventricle immediately after 30 min of MCAO, injected 5＇-bromodeoxyuridine （BrdU） intraperitoneally to label proliferative cells, and microinjected fluorogold （FG） into the substantia nigra at 11 weeks of reperfusion followed by multiple immunostaining of striatonigral projection neurons at 12 weeks. Results We found that pBcl-2 treatment significantly increased the number of newborn neurons （BrdU＋-NeuN＋） in the striatum ipsilateral to the MCAO. We further detected newborn striatonigral projection neurons （BrdU＋-FG＋-NeuN＋） in the ipsilateral striatum at 12 weeks. More interestingly, the number of newborn striatonigral projection neurons （BrdU＋-FG＋） was significantly increased by pBcl-2 treatment compared to that by pEGFP, a control plasmid. Conclusion Taken together, we found that Bcl-2 overexpression in the brain enhanced the generation of newborn striatonigral projection neurons. This provides a potential strategy for promoting the reestablishment of neural networks and brain repair after ischemic injury.
Jian-Jun GuoFang LiuXiao SunJun-Jie HuangMing XuFeng-Yan Sun
