MOLECULAR CHARACTERIZATION OF A CD95 SIGNALING MUTANT

Objective. To study the intracellular signaling events associated with ligation of the surface receptor CD95. Methods. A mutant clone of Jur kat T cells, DD3, which fails to transmit apoptotic signals through CD 95, was selected for study. Surface expression of CD95 and the primary nucleotide sequence of CD95, as well as the functional effects of a m utant CD95 molecule found in DD3, were examined, Results. DD3, while e xhibiting impaired ability to undergo apoptosis after CD95 ligation, r etained the ability to die after ultraviolet light stimulation, A CD95 complementary DNA (cDNA) cloned from DD3 encoded a mutant transmembra ne protein lacking the carboxy-terminal ''death domain.'' Western blot ting confirmed the presence of both wild-type and mutant CD95 protein in DD3, Transfection of the mutant CD95 cDNA into parental Jurkat cell s conferred protection from CD95-mediated apoptosis, Conclusion. A mut ant CD95 receptor lacking the cytoplasmic ''death domain)' can interfe re with wild-type receptor function in T cells.