A novel p75TNF receptor isoform mediating NFkappa B activation.

We report the identification of a novel p75TNF receptor isoform termed icp75TNFR, which is generated by the use of an alternative transcriptional start site within the p75TNFR gene and characterized by regulated intracellular expression. The icp75TNFR protein has an apparent molecular mass of approximately 50 kDa and is recognized by antibodies generated against the transmembrane form of p75TNFR. The icp75TNFR binds the tumor necrosis factor(TNF) and mediates intracellular signaling. Overexpression of the icp75TNFR cDNA results in TNF-induced activation of NFkappaB in a TNF receptor-associated factor 2 (TRAF2)-dependent manner. Thus, our results provide an example for intracellular cytokine receptor activation.