Abstract
The proteasome is the primary protease used by cells for degrading proteins and generating peptide ligands for class I molecules of the major histocompatibility complex. Based on the properties of cells adapted to grow in the presence of the proteasome inhibitor 4-hydroxy-5-iodo-3-nitrophenylacetyl-Leu-Leu-leucinal-vinyl sulfone (NLVS), it was proposed that proteasomes can be replaced by alternative proteolytic systems, particularly a large proteolytic complex with a tripeptidyl peptidase II activity. Here we show that NLVS-adapted cells retain sensitivity to a number of highly specific proteasome inhibitors with regard to antigenic peptide generation, accumulation of polyubiquitinated proteins, degradation of p53, and cell viability. In addition, we show that in the same assays (with a single minor exception), NLVS-adapted cells are about as sensitive as nonselected cells to Ala-Ala-Phe-chloromethylketone, a specific inhibitor of tripeptidyl peptidase II activity. Based on these findings, we conclude that proteasomes still have essential proteolytic functions in adapted cells that are not replaced by Ala-Ala-Phe-chloromethylketone-sensitive proteases.
MeSH terms
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Amino Acid Chloromethyl Ketones / pharmacology
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Aminopeptidases
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Animals
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Antigen Presentation / drug effects
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Antigens / metabolism
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Boronic Acids / pharmacology
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Bortezomib
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CD8-Positive T-Lymphocytes / immunology
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Cell Survival
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Cysteine Endopeptidases
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Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
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Drug Resistance
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Endopeptidases / metabolism
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Enzyme Activation
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H-2 Antigens / immunology
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Leupeptins / pharmacology
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Lymphoma, T-Cell / pathology
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Mice
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Multienzyme Complexes / antagonists & inhibitors*
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Neoplasm Proteins / metabolism
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Oligopeptides / pharmacology*
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Peptide Fragments / metabolism
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Phenols / pharmacology
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Protease Inhibitors / pharmacology*
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Proteasome Endopeptidase Complex
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Protein Processing, Post-Translational / drug effects
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Pyrazines / pharmacology
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Selection, Genetic
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Serine Endopeptidases / physiology
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Sulfones / pharmacology*
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Thymus Neoplasms / pathology
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Tumor Cells, Cultured / drug effects
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Tumor Suppressor Protein p53 / metabolism
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Tyramine* / analogs & derivatives*
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Ubiquitins / metabolism
Substances
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4-hydroxy-5-iodo-3-nitrophenylacetyl-leucyl-leucyl-leucinal-vinyl sulfone
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Amino Acid Chloromethyl Ketones
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Antigens
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Boronic Acids
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H-2 Antigens
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H-2Kb protein, mouse
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Leupeptins
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MG 262
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Multienzyme Complexes
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Neoplasm Proteins
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Oligopeptides
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Peptide Fragments
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Phenols
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Protease Inhibitors
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Pyrazines
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Sulfones
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Tumor Suppressor Protein p53
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Ubiquitins
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YUA001
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alanyl-alanyl-phenylalanine chloromethyl ketone
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Bortezomib
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Endopeptidases
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Aminopeptidases
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Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
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tripeptidyl-peptidase 2
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Serine Endopeptidases
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Cysteine Endopeptidases
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Proteasome Endopeptidase Complex
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benzyloxycarbonylleucyl-leucyl-leucine aldehyde
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Tyramine
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epoxomicin