Apoptotic signaling through CD95 (Fas/Apo-1) activates an acidic sphingomyelinase
نویسندگان
چکیده
Intracellular pathways leading from membrane receptor engagement to apoptotic cell death are still poorly characterized. We investigated the intracellular signaling generated after cross-linking of CD95 (Fas/Apo-1 antigen), a broadly expressed cell surface receptor whose engagement results in triggering of cellular apoptotic programs. DX2, a new functional anti-CD95 monoclonal antibody was produced by immunizing mice with human CD95-transfected L cells. Crosslinking of CD95 with DX2 resulted in the activation of a sphingomyelinase (SMase) in promyelocytic U937 cells, as well as in other human tumor cell lines and in CD95-transfected murine cells, as demonstrated by induction of in vivo sphingomyelin (SM) hydrolysis and generation of ceramide. Direct in vitro measurement of enzymatic activity within CD95-stimulated U937 cell extracts, using labeled SM vesicles as substrates, showed strong SMase activity, which required pH 5.0 for optimal substrate hydrolysis. Finally, all CD95-sensitive cell lines tested could be induced to undergo apoptosis after exposure to cell-permeant C2-ceramide. These data indicate that CD95 cross-linking induces SM breakdown and ceramide production through an acidic SMase, thus providing the first information regarding early signal generation from CD95, and may be relevant in defining the biochemical nature of intracellular messengers leading to apoptotic cell death.
منابع مشابه
Apoptotic Signaling through CD95 (Fas/Apo-1) Activates an Acidic Sphlngomyellnase
From the "Department of Experimental Medicine and Biochemical Sciences, University of Romg "Tor Vergata" and the ~Departraent of Experimental Medicine, University of Rome "La Sapienza" 00161 Rome, Italy; the SDe~rtmem of Experimental Medicine, Uniuersity of L'Aquila, 67100 L'Aquila, Italy; and IIDepartsent of Human Immunology, DNAX Research Institute of Molecular and Cellular Biology, In~, Palo...
متن کاملAcidic Sphingomyelinase (ASM) Is Necessary for Fas-induced GD3 Ganglioside Accumulation and Efficient Apoptosis of Lymphoid Cells
Ceramides deriving from sphingomyelin hydrolysis are important mediators of apoptotic signals originating from Fas (APO-1/CD95). However, definitive evidence for the role played by individual sphingomyelinases is still lacking. We have analyzed lymphoblastoid cell lines derived from patients affected by Niemann Pick disease (NPD), an autosomal recessive disorder caused by loss-of-function mutat...
متن کاملStimulation of CD95 (Fas) blocks T lymphocyte calcium channels through sphingomyelinase and sphingolipids.
Calcium influx through store-operated calcium release-activated calcium channels (CRAC) is required for T cell activation, cytokine synthesis, and proliferation. The CD95 (Apo-1/Fas) receptor plays a role in self-tolerance and tumor immune escape, and it mediates apoptosis in activated T cells. In this paper we show that CD95-stimulation blocks CRAC and Ca(2+) influx in lymphocytes through the ...
متن کاملFunctional expression of Fas and Fas ligand on human gut lamina propria T lymphocytes. A potential role for the acidic sphingomyelinase pathway in normal immunoregulation.
The expression and function of Fas (CD95/APO-1), a cell surface receptor directly responsible for triggering cell death by apoptosis, was investigated on human T lymphocytes resident within the intestinal lamina propria, a major site of antigen challenge and persistent lymphocyte activation. Three color immunofluorescence and FACS analysis indicated that virtually all freshly isolated human gut...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- The Journal of Experimental Medicine
دوره 180 شماره
صفحات -
تاریخ انتشار 1994