Probing proteasome activity and function : cancer diagnostics and mechanism of antigen processing

In cells, proteins are continuously synthesized and degraded to control protein levels and thereby regulate a wide variety of biochemical processes. The proteasome is the main cellular degradation machinery, responsible for the degradation of key proteins involved in the regulation of a wide range of cellular processes, including quality control, cell cycle progression, cell differentiation, signal transduction and apoptosis. Inhibition of the proteasome causes disruption of many regulatory processes, eventually leading to cell death. The observation that many cancer cells are more sensitive to proteasome inhibition than normal cells has led to the development of several proteasome inhibitors for the treatment of cancer. Proteasome activity in its broadest sense is the central theme of this thesis. The development and characterization of different chemical proteasome activity probes that can be used to study proteasome activity in a wide range of tissue types using a variety of assays are described. Subsequently, these probes are used to assess the effects of different proteasome inhibitors in preclinical and clinical studies and to purify proteasome and characterize its activity and composition. Finally, the molecular mechanism of proteasomal antigen splicing is studied.UBL - phd migration 201