title: Ligation of CD40 rescues Ramos-Burkitt lymphoma B cells from calcium ionophore- and antigen receptor-triggered apoptosis by inhibiting activation of the cysteine protease CPP32/Yama and cleavage of its substrate PARP.
abstract: The new and growing family of interleukin-1beta-converting enzyme (ICE) cysteine proteases are now recognised to be major effectors of cellular death by apoptosis. Like other members of this family, the CPP32/Yama proform is activated by processing to its active heterodimeric enzyme or apopain when it likely contributes to the process of apoptosis by cleaving poly(ADP-ribose) polymerase (PARP) and thereby inhibiting much of its DNA repair activity. Apoptosis plays a fundamental role in the regulation of the immune system where it is involved in the selection of both T and B lymphocytes bearing antigen receptor (AgR) for non-self. Cells of the Ramos Epstein-Barr virus (EBV)-genome-negative Burkitt lymphoma (BL) B cell line (Ramos-BL) can be triggered into growth arrest and apoptosis by treating with the calcium ionophore ionomycin or by crosslinking their surface AgR with antibodies directed against immunoglobulin (Ig)M (anti-IgM). Ionomycin- and AgR-triggered growth arrest and apoptosis are arrested by signals transduced through the surface CD40 of Ramos-BL B cells. Both ionomycin and anti-IgM trigger activation of CPP32 and cleavage of PARP prior to the onset of apoptosis; this process is abrogated by treatment with anti-CD40 and is independent of Bcl-2 expression. A tripeptide inhibitor of ICE family cysteine proteases, Z-Val-Ala-Asp-fluoromethylketone (zVAD-fmk) inhibits ionomycin- and AgR-triggered CPP32 activation, PARP cleavage and apoptosis, but not growth arrest, in Ramos-BL B cells. Thus, in this report we demonstrate that in a physiological system, activation of endogenous members of the ICE family, including CPP32, and cleavage of the death substrate PARP act as major effectors of apoptotic death.
authors.affiliation: Department of Biochemistry, The University of Oxford, UK.
authors.forename: S
authors.initials: S
authors.lastname: An
authors.forename: K A
authors.initials: KA
authors.lastname: Knox
mesh_terms: D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000276:immunology; D017209:Apoptosis / Q000502:physiology*; D001402:B-Lymphocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism; D002051:Burkitt Lymphoma; D019013:CD40 Antigens / Q000276:immunology / Q000378:metabolism*; D002118:Calcium; D053148:Caspase 3; D020169:Caspases; D002460:Cell Line; D002675:Child, Preschool; D003546:Cysteine Endopeptidases / Q000187:drug effects / Q000378:metabolism*; D006801:Humans; D007075:Immunoglobulin M / Q000276:immunology; D015759:Ionomycin / Q000494:pharmacology; D007476:Ionophores / Q000494:pharmacology; D008297:Male; D051379:Mice; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D011947:Receptors, Antigen, B-Cell / Q000378:metabolism*; D012756:Sheep; D013997:Time Factors
chemical_list: D000590:Amino Acid Chloromethyl Ketones; D000906:Antibodies; D019013:CD40 Antigens; D007075:Immunoglobulin M; D007476:Ionophores; D011480:Protease Inhibitors; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D011947:Receptors, Antigen, B-Cell; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D015759:Ionomycin; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases; D002118:Calcium