Activation of p42/p44 mitogen-activated protein kinases (MAPK) and p38 MAPK by tumor necrosis factor (TNF) is mediated through the death domain of the 55-kDa TNF receptor

In the mouse fibrosarcoma cell line L929sA, tumor necrosis factor (TNF) sti mulates activation of the stress-responsive p38 mitogen-activated protein k inase (MAPK), as well as the classical p42 and p44 MAPK. TNF signaling can be mediated by p55 or p75 TNF receptors, Here, we demonstrate that TNF-R55 is sufficient to activate p42/p44 MAPK and p38 MAPK. Moreover, by expressin g different membrane-bound or purely cytoplasmic truncations of TNF-R55, we show that the intracellular death domain of TNF-R55 is the crucial domain involved. The cytoplasmic membrane-proximal region of TNF-R55, known to ind uce neutral sphingomyelinase activation, is not required for activation of p38 MAPK or p42/p44 MAPK. (C) 1998 Federation of European Biochemical Socie ties.