scholarly journals Tumor Necrosis Factor Receptor–associated Factor 6 (TRAF6) Stimulates Extracellular Signal–regulated Kinase (ERK) Activity in CD40 Signaling Along a Ras-independent Pathway

1998 ◽  
Vol 187 (2) ◽  
pp. 237-244 ◽  
Author(s):  
Masaki Kashiwada ◽  
Yumiko Shirakata ◽  
Jun-Ichiro Inoue ◽  
Hiroyasu Nakano ◽  
Kenji Okazaki ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Deletion Mutant ◽  
Tumor Necrosis Factor Receptor ◽  
Dominant Negative ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Erk Activity ◽  
Necrosis Factor

CD40 activates nuclear factor kappa B (NFκB) and the mitogen-activated protein kinase (MAPK) subfamily, including extracellular signal–regulated kinase (ERK). The CD40 cytoplasmic tail interacts with tumor necrosis factor receptor–associated factor (TRAF)2, TRAF3, TRAF5, and TRAF6. These TRAF proteins, with the exception of TRAF3, are required for NFκB activation. Here we report that transient expression of TRAF6 stimulated both ERK and NFκB activity in the 293 cell line. Coexpression of the dominant-negative H-Ras did not affect TRAF6-mediated ERK activity, suggesting that TRAF6 may activate ERK along a Ras-independent pathway. The deletion mutant of TRAF6 lacking the NH2-terminal domain acted as a dominant-negative mutant to suppress ERK activation by full-length CD40 and suppress prominently ERK activation by a deletion mutant of CD40 only containing the binding site for TRAF6 in the cytoplasmic tail (CD40Δ246). Transient expression of the dominant-negative H-Ras significantly suppressed ERK activation by full-length CD40, but marginally suppressed ERK activation by CD40Δ246, compatible with the possibility that TRAF6 is a major transducer of ERK activation by CD40Δ246, whose activity is mediated by a Ras-independent pathway. These results suggest that CD40 activates ERK by both a Ras-dependent pathway and a Ras-independent pathway in which TRAF6 could be involved.

scholarly journals Extracellular Signal-regulated Kinase Phosphorylates Tumor Necrosis Factor α-converting Enzyme at Threonine 735: A Potential Role in Regulated Shedding

2002 ◽  
Vol 13 (6) ◽  
pp. 2031-2044 ◽  
Author(s):  
Elena Dı́az-Rodrı́guez ◽  
Juan Carlos Montero ◽  
Azucena Esparı́s-Ogando ◽  
Laura Yuste ◽  
Atanasio Pandiella
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Α ◽  
Converting Enzyme ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Factor Α ◽  
Necrosis Factor

The ectodomain of certain transmembrane proteins can be released by the action of cell surface proteases, termed secretases. Here we have investigated how mitogen-activated protein kinases (MAPKs) control the shedding of membrane proteins. We show that extracellular signal-regulated kinase (Erk) acts as an intermediate in protein kinase C-regulated TrkA cleavage. We report that the cytosolic tail of the tumor necrosis factor α-converting enzyme (TACE) is phosphorylated by Erk at threonine 735. In addition, we show that Erk and TACE associate. This association is favored by Erk activation and by the presence of threonine 735. In contrast to the Erk route, the p38 MAPK was able to stimulate TrkA cleavage in cells devoid of TACE activity, indicating that other proteases are also involved in TrkA shedding. These results demonstrate that secretases are able to discriminate between the different stimuli that trigger membrane protein ectodomain cleavage and indicate that phosphorylation by MAPKs may regulate the proteolytic function of membrane secretases.

scholarly journals Keratins Modulate c-Flip/Extracellular Signal-Regulated Kinase 1 and 2 Antiapoptotic Signaling in Simple Epithelial Cells

2004 ◽  
Vol 24 (16) ◽  
pp. 7072-7081 ◽  
Author(s):  
Stéphane Gilbert ◽  
Anne Loranger ◽  
Normand Marceau
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis Factor Alpha ◽  
Tumor Necrosis ◽  
Null Mouse ◽  
Wild Type ◽  
Necrosis Factor Alpha ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Factor Alpha ◽  
Necrosis Factor

ABSTRACT Among the large family of intermediate filament proteins, the keratin 8 and 18 (K8/K18) pair constitutes a hallmark for all simple epithelial cells, such as hepatocytes and mammary cells. Functional studies with different cell models have suggested that K8/K18 are involved in simple epithelial cell resistance to several forms of stress that may lead to cell death. We have reported recently that K8/K18-deprived hepatocytes from K8-null mice are more sensitive to Fas-mediated apoptosis. Here we show that upon Fas, tumor necrosis factor alpha receptor, or tumor necrosis factor alpha-related apoptosis-inducing ligand receptor stimulation, an inhibition of extracellular signal-regulated kinase 1 and 2 (ERK1/2) activation sensitizes wild-type but not K8-null mouse hepatocytes to apoptosis and that a much weaker ERK1/2 activation occurs in K8-null hepatocytes. In turn, this impaired ERK1/2 activation in K8-null hepatocytes is associated with a drastic reduction in c-Flip protein, an event that also holds in a K8-null mouse mammary cell line. c-Flip, along with Raf-1, is part of a K8/K18-immunoisolated complex from wild-type hepatocytes, and Fas stimulation leads to further c-Flip and Raf-1 recruitment in the complex. This points to a new regulatory role of simple epithelium keratins in the c-Flip/ERK1/2 antiapoptotic signaling pathway.

scholarly journals Poxvirus Tumor Necrosis Factor Receptor (TNFR)-Like T2 Proteins Contain a Conserved Preligand Assembly Domain That Inhibits Cellular TNFR1-Induced Cell Death

2006 ◽  
Vol 80 (18) ◽  
pp. 9300-9309 ◽  
Author(s):  
Lisa M. Sedger ◽  
Sarah R. Osvath ◽  
Xiao-Ming Xu ◽  
Grace Li ◽  
Francis K.-M. Chan ◽  
...  
Keyword(s):  
Tumor Necrosis Factor ◽  
Tumor Necrosis ◽  
Tumor Necrosis Factor Receptor ◽  
Surface Expression ◽  
Myxoma Virus ◽  
Dominant Negative ◽  
Trail Receptors ◽  
Tnf Α ◽  
Dominant Negative Inhibitor ◽  
Necrosis Factor

ABSTRACT The poxvirus tumor necrosis factor receptor (TNFR) homologue T2 has immunomodulatory properties; secreted myxoma virus T2 (M-T2) protein binds and inhibits rabbit TNF-α, while intracellular M-T2 blocks virus-induced lymphocyte apoptosis. Here, we define the antiapoptotic function as inhibition of TNFR-mediated death via a highly conserved viral preligand assembly domain (vPLAD). Jurkat cell lines constitutively expressing M-T2 were generated and shown to be resistant to UV irradiation-, etoposide-, and cycloheximide-induced death. These cells were also resistant to human TNF-α, but M-T2 expression did not alter surface expression levels of TNFRs. Previous studies indicated that T2's antiapoptotic function was conferred by the N-terminal region of the protein, and further examination of this region revealed a highly conserved N-terminal vPLAD, which is present in all poxvirus T2-like molecules. In cellular TNFRs and TNF-α-related apoptosis-inducing ligand (TRAIL) receptors (TRAILRs), PLAD controls receptor signaling competency prior to ligand binding. Here, we show that M-T2 potently inhibits TNFR1-induced death in a manner requiring the M-T2 vPLAD. Furthermore, we demonstrate that M-T2 physically associates with and colocalizes with human TNFRs but does not prevent human TNF-α binding to cellular receptors. Thus, M-T2 vPLAD is a species-nonspecific dominant-negative inhibitor of cellular TNFR1 function. Given that the PLAD is conserved in all known poxvirus T2-like molecules, we predict that it plays an important function in each of these proteins. Moreover, that the vPLAD confers an important antiapoptotic function confirms this domain as a potential target in the development of the next generation of TNF-α/TNFR therapeutics.

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