The effect of altered proteasome activity on expPABPN1 accumulation and aggregation. A) Substantial deregulation of proteasome and immunoproteasome encoding genes in mice and humans. Down-regulation (green) is more pronounced in the core subunit of the proteasome. Immunoproteasome shows consistent up-regulation (red) in both organisms. B) Western blot analysis of YFP-Ala16-PABPN1 transfected C2C12 cells that were treated with 5 μM MG132 or 5 nM PR619. Control cells were treated with DMSO. C) Images show YFP-Ala16-PABPN1 localization in C2C12 after mock-treatment (DMSO), 5 μM MG132 or 5 U/ml IFNγ. Scale bar equals 10 μm. Histograms show the integrated intensity of YFP-Ala16-PABPN1 (i) or Histone4-CFP (control) (ii), and the percentage of cells with INI in YFP-Ala16-PABPN1 expressing cells (iii). Averages represent 509, 773 and 476 cells for DMSO, MG132 and IFNγ, respectively. Significant difference between treatments is reflected by P-values.