Selective inhibition of dipeptidyl peptidase I, not caspases, prevents the partial processing of procaspase-3 in CD3-activated human CD8(+) T lymphocytes.
Activation of primary human T cells by anti-CD3 and interleukin-2 resulted in partial processing of procaspase-3 in activated nonapoptotic (Delta Psi(m)high) CD8(+) T cells but not in CD4(+) T cells. Apical caspases-8 and -9 were not activated, and Bid was not processed to truncated Bid. Boc-D.fmk, a broad spectrum caspase inhibitor, did not prevent this process, whereas GF.dmk, a selective inhibitor of dipeptidyl peptidase I, was effective. Dipeptidyl peptidase I is required for the activation of granule-associated serine proteases. It is enriched in the cytolytic granules of cytotoxic lymphocytes, where it promotes the proteolytic activation of progranzymes A and B. Inhibition of granzyme B (GrB)-like serine proteases by Z-AAD.cmk prevented partial processing of procapase-3, whereas inhibition of GrA activity by D-FPR.cmk had no effect. Specific inhibitors of other lysosomal proteases such as cathepsins B, L, and D did not interfere in this event. Patients with Chediak-Higashi syndrome or with perforin deficiency also displayed partial processing of procaspase-3, excluding the involvement of granule exocytosis for the delivery of the serine protease in cause. The p20/p12 processing pattern of procaspase-3 in our model points to GrB, the sole serine protease with caspase activity. Small amounts of GrB were indeed exported from cytolytic granules to the cytosol of a significant fraction of GrB-positive cells.
Bidère
Nicolas
N
Laboratoire de Greffes d'Epithéliums et Régulation de l'Activation Lymphocytaire, Unité INSERM 542, Hôpital Paul Brousse, 94807 Villejuif, France.
Briet
Marie
M
Dürrbach
Antoine
A
Dumont
Céline
C
Feldmann
Jérôme
J
Charpentier
Bernard
B
de Saint-Basile
Geneviève
G
Senik
Anna
A
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D015703:Antigens, CD / Q000502:physiology; D017252:CD3 Complex / Q000502:physiology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism*; D020789:Cathepsin C / Q000037:antagonists & inhibitors*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004792:Enzyme Precursors / Q000378:metabolism*; D006801:Humans; D008213:Lymphocyte Activation; D011480:Protease Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D021122:Protein Subunits; D021381:Protein Transport
D000590:Amino Acid Chloromethyl Ketones; D015703:Antigens, CD; D017252:CD3 Complex; D015853:Cysteine Proteinase Inhibitors; D004792:Enzyme Precursors; D011480:Protease Inhibitors; D021122:Protein Subunits; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D020789:Cathepsin C; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases