Regulation of the proteasome in the ageing model Podospora anserina

The ‘free radical theory' states that reactive oxygen species accumulate during the life of a cell and oxidise DNA, lipids and proteins, thereby leading to impaired functions, ageing and finally death. The proteasome degrades damaged proteins and is involved in ageing processes, but its role is not precisely elucidated. Here we report data aimed to investigate the role of the proteasome on organismal ageing of the fungal ageing model Podospora anserina.

We constructed P. anserina strains expressing Gfp-cl1 to study the activity of the proteasome during ageing. GFP-CL1 fusion proteins are degraded in a proteasome dependent manner. Treatment of Gfp-cl1_OEx strains with a specific proteasome inhibitor leads to increased GFP fluorescence, demonstrating the functionality of the assay. The fluorescence of Gfp-cl1_OEx strains is reduced during ageing and heat stress, suggesting an enhancement of proteasome activity, but the expression of Gfp-cl1 has to be taken into consideration and further studies are necessary to verify the obtained data. Analyses of expression and protein abundance of the catalytic proteasome subunits revealed no significant changes during ageing. Finally, we constructed over-expression strains of the 20S-proteasome subunits PaPre2 (β5) and PaPre3 (β1) to investigate the effect on the organism. In contrast to findings from human fibroblasts this is not sufficient to increase 20S proteasome abundance in P. anserina.