ACID SPHINGOMYELINASE IS NOT ESSENTIAL FOR THE IL-1 AND TUMOR-NECROSIS-FACTOR RECEPTOR SIGNALING PATHWAY LEADING TO NFKB ACTIVATION

A recent report has suggested that tumor necrosis factor (TNF) utilize s acid sphingomyelinase (SMase) pathway to activate NFkB (Schutze at a l. 1992. Cell 71:765). To directly investigate the role of acid SMase in IL-1 and TNF receptor-mediated signal transduction, we examined the ability of Niemann - Pick disease (NPD) type A fibroblasts, which are deficient in acid SMase, to induce IL-8 gene expression through activ ating NFkB. Unexpectedly, IL-1 alpha and TNF-alpha efficiently induced IL-8 production and IL-8 mRNA in NPD type A fibroblasts as in normal fibroblasts. Furthermore, activation of NFkB was also induced in NPD t ype A fibroblasts in response to IL-1 alpha and TNF-alpha stimulation to a similar extent as in normal fibroblasts. These results provide ev idence that acid SMase is not essential in IL-1 and TNF receptor signa ling leading to NFkB activation as well as the cytokine gene activatio n which is regulated by NFkB.