Objective: To detect the role of Bcl-2-associated athanogene 3 (BAG3) in regulating autophagy in PC12 cells and explore the underlying mechanisms of it.

Background: Increasing data indicate that autophagy play an important role in Parkinson’s disease (PD). But how to choose autophagic regulation target and control the degree of autophagy activation have troubled researchers for many years and need to be solved urgently. Recently, it has been reported that BAG3 mediates chaperone-based aggresome-targeting and selective autophagy of misfolded proteins. However, the mechanisms of it are not yet fully understood. And till now there’s no data show the role of selective autophagy mediated by BAG3 in dopaminergic neuron.

Methods: In the present study, over-expression of wild-type α-synuclein PC12 cells (WT-PC12 cells) were treatment with MG132, an inhibitor of proteasome, to developing cell model of PD. The effects of BAG3 in α-syncline’s autophagic degradation were investigated by MTT, Western blotting, Reverse transcription PCR and Immunoprecipitation. Furthermore, the regulatory mechanisms of BAG3 in autophagy were explored after overexpression or RNA interference (RNAi) of BAG3.

Results: It was found that after treatment with MG132, cell viability of WT-PC12 cells decreased in a dose dependent manner. MG132 significantly upregulated the expression of α-synuclein, but it has no effect on the gene level of it in WT-PC12 cell lines. What’s more, MG132 increased the expression BAG3, autophagy-related proteins LC3-II and P62 in WT-PC12 in a dose dependent manner. We also found that BAG3 overexpression was sufficient to enhance LC3-II level induced by MG132 in WT-PC12 cells and promote the cleareance of α-synuclein. Knockdown of BAG3 abolished the changes in LC3-II protein level induced by MG132 in WT-PC12 and result in the formation of α-synuclein. The underlying mechanisms of BAG3 in regulating autophagy rely on the HSP70-BAG3-P62 complex.

Conclusions: These results indicate that BAG3 involves in the autophagic degradation of α-synuclein in WT-PC12 cells and it has a neuroprotective effect on the injury of dopaminergic neurons induced by MG132. Increase BAG3 levels could provide a therapeutic approach to Parkinson’s disease.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-role-and-underlying-mechanisms-of-bag3-in-regulating-autophagy-in-pc12-cells/