Dissection of Pathways Leading to Antigen Receptor-Induced and Fas/CD95-Induced Apoptosis in Human B Cells

Autor: Susanne M. A. Lens, Bianca F. A. den Drijver, Andy J. G. Pötgens, Kiki Tesselaar, Marinus H. J. van Oers, René A. W. van Lier
Rok vydání: 1998
Předmět:
Zdroj: The Journal of Immunology. 160:6083-6092
ISSN: 1550-6606
0022-1767
DOI: 10.4049/jimmunol.160.12.6083
Popis: To dissect intracellular pathways involved in B cell Ag receptor (BCR)-mediated and Fas-induced human B cell death, we isolated clones of the Burkitt lymphoma cell line Ramos with different apoptosis sensitivities. Selection for sensitivity to Fas-induced apoptosis also selected for clones with enhanced BCR death sensitivity and vice versa. In contrast, clones resistant to Fas-mediated apoptosis could still undergo BCR-induced cell death. Based on the functional phenotypes of these clones, we hypothesized that both receptor-induced apoptosis pathways are initially distinct but may eventually converge. Indeed, ligation of both Fas and BCR resulted in cleavage of the IL-1β-converting enzyme/Ced-3-like protease caspase 3 and its substrates Ac-Asp-Glu-Val-Asp-aldehyde and poly(ADP-ribose) polymerase. Markedly, qualitative differences in the caspase 3 cleavage pattern induced by Fas or BCR ligation were observed; whereas Fas ligation generated caspase 3 cleavage products of 19/20 and 17 kDa, only the latter cleavage product was found upon BCR cross-linking. The caspase inhibitor Val-Ala-Asp-fluoromethylketone blocked both Fas- and BCR-mediated apoptosis, but differentially affected caspase 3 cleavage induced by either stimulus. Finally, overexpression of a Fas-associated death domain (FADD) dominant-negative mutant protein was found to inhibit Fas-induced apoptosis but not BCR-induced apoptosis. Together our findings imply that Fas and BCR couple, via FADD-dependent and FADD-independent mechanisms, respectively, to distinct proteases upstream of caspase 3.
Databáze: OpenAIRE
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