Structural MS approaches (Top-down, HDX-MS) are highly complementary to proteomics to characterize Proteasome heterogeneity, dynamics, Post-Translational Modifications (PTMs), and interaction interfaces.
We have optimized them to work on poorly concentrated and very heterogeneous proteasome complexes. New important mechanistic insights in proteasome regulation could be highlighted (Lesne et al. Bioinformatics and biology insights 2019; Lesne et al. Nature Commun. 2020).
The 20S proteasome is crucial for cellular protein degradation, and its dysregulation has been implicated in various diseases, offering a promising therapeutic target. In the past years, efforts led to the development of the first generation of proteasome inhibitors, including the three USA FDA-approved drugs for the treatment of multiple myeloma and mantle cell lymphoma, and the second generation of proteasome inhibitors, which is more specific to the immunoproteasome subtype. However, various side effects are associated with these inhibitors that target proteasome catalytic sites and completely block cellular proteasomal activity. The toxicity could therefore be considerably reduced by increasing specificity, e.g. directly targeting certain proteasome subtype linked to their activators, such as PA28γ and PA28αβ.
This study involved the identification of compounds that specifically inhibit 20S-PA28 pairs and the characterization of their potential mechanism of action using structural mass spectrometry. Additional characterization and development of these compounds could enhance our understanding of 20S-PA28 regulation and its connection to diseases like cancer and immune disorders. This work may pave the way for future treatments that tackle the challenges of resistance and significant side effects associated with current proteasome inhibitors..