Effect of proteasome inhibition on total and poly-ubiquitylated proteomes of human A549 lung adenocarcinoma cells in different proliferation states

Cellular stress responses are crucial for survival in sub-optimal conditions, and almost invar-iably involve proteome-wide alterations at the levels of protein abundance and post-translational modification with poly-ubiquitin chains (poly-ubiquitylation). However, most of our understanding of human cell stress responses at the protein level stems from experiments in rapidly-dividing cell culture models. Here, we used the A549 human diploid lung adenocarci-noma cell line (alveolar, type-2) in proliferating or bleomycin-induced senescent states, to ex-plore their responses to a severe proteotoxic stress with the proteasome inhibitor bortezomib (100 nM for 24 hours) at the total and poly-ubiquitylated proteome levels.