Aberrant Decrease of the Endogenous SIRT3 and Increases of Acetylated Proteins in Scrapie-Infected Cell Line SMB-S15 and in the Brains of Experimental Mice

Abstract

The linkage between mitochondrial dysfunction and neurodegenerative diseases including prion diseases has been frequently reported. As the major deacetylase in mitochondria, SIRT3 plays a crucial part in regulating the function of many mitochondrial proteins. Although SIRT3 was reported to be linked to several neurodegenerative diseases, it is still unknown if SIRT3 is involved in prion diseases. In this study, we have presented a substantially declined status of mitochondrial SIRT3 in both the levels of cultured cells and an experimental rodent model during scrapie prion replication and infection. Such decreased SIRT3 activity led to a decreased deacetylating activity, resulting in increases of the acetylated forms of some substrates of SIRT3 in cells, such as SOD2 and ATP5β. Declined SOD2 and ATP5β activities subsequently caused an increase of intracellular ROS and a reduction of ATP. Furthermore, we have also proposed evidence that the activity of cellular SIRT3 is partially recovered when abnormal prion propagation in the cultured cells is removed by resveratrol. Those data emphasize a close connection between the prion replication and mitochondrial deacetylation due to SIRT3, thereby partially explaining mitochondrial dysfunction in prion diseases.

Global profiles of a cetylated proteins in the brains of scrapie agents 139A- and ME7-infected mice collected at mid-early, mid-late and terminal stage

“…Previously, we have described that the levels and activities of Sirt1, a class III histone deacetylase, were remarkably decreased in the brains of different scrapie infected rodent models and in a prion infected cell line SMB-S15, resulting in increases of the acetylating forms of some Sirt1 target proteins, such as P53, PGC-1, and STAT3 [19]. Recently, we have also con rmed the declined levels of Sirt3 in the brain tissues of several scrapie infected mice and in SMB-S15 cells, leading to increases of acetylating forms of SOD2 and ATP5β that subsequently induce increase of intracellular ROS and reduction of ATP [20]. Aberrant alterations of acetylation modi cations for other proteins have been also found in the brain tissues or the models in vitro of several neurodegenerative diseases, e.g., tau, microtubules, SOD1 [21][22][23].…”

Aberrant SENP1-SUMO-Sirt3 Signaling Causes the Disturbances of Mitochondrial Deacetylation and Oxidative Phosphorylation in Prion-Infected Animal and Cell Models

“…Low levels of brain Sirt1 and Sirt3 have been addressed in various prion-infected rodent models, leading to a decrease of deacetylating activity and increases of acetylated forms of a series of target proteins. , Translocase of outer mitochondrial membrane 20 (TOMM20) is a receptor and a key subunit of the TOM complex, which is important to the importing of mitochondrial proteins . Double-staining IFAs with anti-Sirt3 and anti-Tomm20 illustrated morphological colocalization of these two signals in SMB cells, highlighting the distribution of Sirt3 in mitochondria (Figure A).…”

“…Our previous study has revealed aberrant alterations in the global profiles of the brain acetylated proteins by proteomics during prion infection in scrapie mouse models, showing remarkably inhibited acetylation in the early stage and relatively enhanced acetylation in the late stage . Two major components in the sirtuin family, Sirt3 and Sirt1, are markedly dysregulated in the brains of prion-infected animal and cell models. , In this report, we have identified that along with the reductions of the level and activity of Sirt3, the acetylated forms of several key enzymes in oxidative phosphorylation increase in the brains infected with scrapie agents at the terminal stage and in the prion-infected cell model. We also provide evidence that the decreased Sirt3 activity is associated with the increase of SUMOylation and decrease of SENP during prion infection.…”

“…14 An abnormal down-regulation of Sirt3 has been reported in prion-infected mice and cell models, resulting in increases of acetylated forms of many downstream target proteins. 15 However, the potential changes in acetylation of enzymes in oxidative phosphorylation and mitochondrial energy supply remain unknown. Recently, Sirt3 has been reported as a SUMOylated protein.…”

“…The activities of numerous metabolic enzymes in mitochondria can be regulated by acetylation. , As a major deacetylase, Sirt3 plays an important role in maintaining mitochondrial homeostasis as a stress response protein. , Acetylation levels of enzymes in oxidative phosphorylation can be regulated by Sirt3 . An abnormal down-regulation of Sirt3 has been reported in prion-infected mice and cell models, resulting in increases of acetylated forms of many downstream target proteins . However, the potential changes in acetylation of enzymes in oxidative phosphorylation and mitochondrial energy supply remain unknown.…”