Fas Activation of the p38 Mitogen-Activated Protein Kinase Signalling Pathway Requires ICE/CED-3 Family Proteases

Abstract

The Fas receptor mediates a signalling cascade resulting in programmed cell death (apoptosis) within hours of receptor cross-linking. In this study Fas activated the stress-responsive mitogen-activated protein kinases, p38 and JNK, within 2 h in Jurkat T lymphocytes but not the mitogen-responsive kinase ERK1 or pp70 S6k . Fas activation of p38 correlated temporally with the onset of apoptosis, and transfection of constitutively active MKK3(glu), an upstream regulator of p38, potentiated Fas-induced cell death, suggesting a potential involvement of the MKK3/p38 activation pathway in Fas-mediated apoptosis. Fas has been shown to require ICE (interleukin-1␤-converting enzyme) family proteases to induce apoptosis from studies utilizing the cowpox ICE inhibitor protein CrmA, the synthetic tetrapeptide ICE inhibitor YVAD-CMK, and the tripeptide pan-ICE inhibitor Z-VAD-FMK. In this study, crmA antagonized, and YVAD-CMK and Z-VAD-FMK completely inhibited, Fas activation of p38 kinase activity, demonstrating that Fas-dependent activation of p38 requires ICE/CED-3 family members and conversely that the MKK3/p38 activation cascade represents a downstream target for the ICE/CED-3 family proteases. Intriguingly, p38 activation by sorbitol and etoposide was resistant to YVAD-CMK and Z-VAD-FMK, suggesting the existence of an additional mechanism(s) of p38 regulation. The ICE/CED-3 family-p38 regulatory relationship described in the current work indicates that in addition to the previously described destructive cleavage of substrates such as poly(ADP ribose) polymerase, lamins, and topoisomerase, the apoptotic cysteine proteases also function to regulate stress kinase signalling cascades.Fas (APO-1/CD95) encodes a transmembrane type I receptor belonging to the tumor necrosis factor (TNF) receptor superfamily which includes TNF receptors 1 and 2 (TNFR1 and TNFR2), nerve growth factor (NGF) receptor, CD27, CD30, CD40, and OX40 (47, 67; reviewed in references 65 and 80). The cognate Fas ligand is a type II transmembrane protein belonging to the TNF family (83). The Fas receptor system has been extensively studied as a model of apoptosis, since crosslinking of the Fas receptor with Fas ligand or specific agonist antibodies results in rapid programmed cell death (47,89,97).Fas-induced apoptosis plays an important role in T-and B-cell homeostasis in the immune system and participates in T-cell activation-induced cell death (5,22,48), the elimination of autoreactive B cells (71), and the maintenance of sites of immune privilege (1). lpr mice defective in Fas (93), gld mice defective in Fas ligand (84), and humans with mutations in Fas (34, 73) all develop an autoimmune, lymphoproliferative disorder, indicating that Fas-induced death plays an important role in the peripheral deletion of lymphocytes.The essential signalling events linking Fas receptor crosslinking to apoptosis have been the subject of intense investigation. The intracellular domain of Fas contains an approximately 70-amino-acid "death domain" required for the induction...

Degradation of eukaryotic polypeptide chain initiation factor (eIF) 4G in response to induction of apoptosis in human lymphoma cell lines

“…The point of convergence of these pathways at the level of eIF4G is most likely the activation of one or more`executioner' caspases (Longthorne and Williams, 1997; Kamada et al, 1997;Cohen, 1997). This is consistent with the ability of the caspase inhibitors (Z-VAD.FMK and Z-DEVD.FMK; Dolle et al, 1994;Fearnhead et al, 1995;Perry et al, 1997;Juo et al, 1997), but not calpain or proteosome inhibitors (data not shown), to block the disappearance of eIF4G regardless of the apoptosis-inducing stimulus.…”

“…BJAB and Jurkat cells respectively, since such cell types are sensitive to a wide range of physiological signals that can inhibit proliferation and induce apoptosis (programmed cell death). Examples of such conditions include deprivation of serum growth factors (Kawanishi, 1997), inhibition of protein synthesis with cycloheximide (Ishii et al, 1995, treatment with antibodies to the CD95 Fas antigen (Oehm et al, 1992;Juo et al, 1997), or exposure to etoposide, an inhibitor of DNA topoisomerase II (Sinha, 1995). Apoptosis is characterized by a series of cellular changes that lead ultimately to cell death (Hale et al, 1996;Rowan and Fisher, 1997;Nagata, 1997;Salvesen and Dixit, 1997).…”

Differential phosphorylation of mitogen-activated protein kinase families by epidermal growth factor and ultraviolet B irradiation in SV40-transformed human keratinocytes

“…Fas-induced apoptosis involves the activation of MKK6 and/or MKK3 by ICE-like protease, where MKK3/6 activates CPP32-like protease(s) to promote cell death and also activates p38 signaling pathway [40,41]. Anti-Fas antibody and interferon …”

Requirement of protein kinase (Krs/MST) activation for MT-21-induced apoptosis

“…Activation of JNK has been observed to correlate with the apoptosis induction of various stimuli, including nerve growth factor withdrawal, B-cell receptor cross-linking and Fas ligation (Xia et al, 1995;Cahill et al, 1996;Graves et al, 1996;Wilson et al, 1996;Juo et al, 1997). Caspase inhibitors can block JNK activation induced by Fas cross-linking, indicating that this pathway may function downstream of caspase activation (Cahill, et al, 1996;Juo et al, 1997). In fact, MT-21-induced JNK activation was suppressed by Z-Asp and by expression of kinase-inactive Krs proteins during the process of apoptotic induction (Figure 7b).…”