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Induction of Apoptosis by Apo-2 Ligand, a New Member of the Tumor Necrosis Factor Cytokine Family*

Open AccessPublished:May 31, 1996DOI:https://doi.org/10.1074/jbc.271.22.12687
      Cytokines in the tumor necrosis factor (TNF) family regulate development and function of the immune system. We have isolated a new member of this family, designated Apo-2 ligand (Apo-2L), via an expressed sequence tag. Apo-2L is a 281-amino acid protein, related most closely to Fas/Apo-1 ligand. Transfected Apo-2L is expressed at the cell surface with its C terminus exposed, indicating a type II transmembrane protein topology. Like Fas/Apo-1 ligand and TNF, the C-terminal extracellular region of Apo-2L (amino acids 114-281) exhibits a homotrimeric subunit structure. Soluble Apo-2L induces extensive apoptosis in lymphoid as well as non-lymphoid tumor cell lines. The effect of Apo-2L is not inhibited by soluble Fas/Apo-1 and TNF receptors; moreover, expression of human Fas/Apo-1 in mouse fibroblasts, which confers sensitivity to induction of apoptosis by agonistic anti-Fas/Apo-1 antibody, does not confer sensitivity to Apo-2L. Hence, Apo-2L acts via a receptor which is distinct from Fas/Apo-1 and TNF receptors. These results suggest that, along with other family members such as Fas/Apo-1 ligand and TNF, Apo-2L may serve as an extracellular signal that triggers programmed cell death.

      INTRODUCTION

      TNF
      The abbreviations used are: TNF
      tumor necrosis factor
      TNFR
      tumor necrosis factor receptor
      EST
      expressed sequenced tag
      mAb
      monoclonal antibody
      PI
      propidium iodide
      LT
      lymphotoxin
      FACS
      fluorescence-activated cell sorter.
      family cytokines modulate host defense mechanisms via a corresponding family of receptors (
      • Beutler B.
      • van Huffel C.
      ,
      • Smith C.A.
      • Farrah T.
      • Goodwin R.G.
      ,
      • Gruss H.J.
      • Dower S.K.
      ). Most TNF family cytokines are expressed as type II transmembrane proteins, whose C-terminal extracellular domain is processed proteolytically to form a soluble homotrimeric molecule. In contrast, the members of the TNF receptor (TNFR) family are type I transmembrane proteins. In both families, sequence homology is found mainly in the extracellular regions, which mediate ligand-receptor binding.
      Members of the TNF family have diverse biological actions, including T cell co-stimulation, induction of B cell proliferation and differentiation, and macrophage activation (
      • Beutler B.
      • van Huffel C.
      ,
      • Smith C.A.
      • Farrah T.
      • Goodwin R.G.
      ,
      • Gruss H.J.
      • Dower S.K.
      ). In addition, certain TNF family members regulate the elimination of unwanted immune cells by inducing programmed cell death (apoptosis). For example, Fas/Apo-1 ligand (Fas/Apo-1L) plays a key role in peripheral deletion of self-reactive lymphocytes, as suggested by the autoimmune phenotype of the mouse mutations lpr and gld, which occur, respectively, in the Fas/Apo-1 receptor or ligand genes (
      • Krammer P.H.
      • Behrmann I.
      • Daniel P.
      • Dhein J.
      • Debatin K.M.
      ,
      • Nagata S.
      • Golstein P.
      ). In addition, Fas/Apo-1L is involved in apoptosis of B cells and CD4+ T cells subsequent to stimulation by antigen, while TNF mediates a similar function in CD8+ T cells (
      • Krammer P.H.
      • Behrmann I.
      • Daniel P.
      • Dhein J.
      • Debatin K.M.
      ,
      • Nagata S.
      • Golstein P.
      ,
      • Daniel P.T.
      • Krammer P.H.
      ,
      • Zheng L.
      • Fisher G.
      • Miller R.E.
      • Peschon J.
      • Lynch D.H.
      • Lenardo M.J.
      ).
      In this article, we describe a new member of the TNF cytokine family. We have designated this protein Apo-2L, because it resembles the Fas/Apo-1L in its amino acid sequence, as well as in its ability to induce apoptosis. Apo-2L appears to act via a receptor which is distinct from Fas/Apo-1 and TNF receptors, suggesting that its biological role is unique.

      Acknowledgments

      We thank A. Gurney and W. Wood for EST searches, N. Vasquez and P. Jardieu for 9D cells, M. Vasser, P. Ng, and P. Jhurani for oligonucleotide synthesis, M. Hamner for help with DNA sequencing, J. Yashio and W. Henzel for protein sequencing, J. Chin and K. Bauer for help and advice with FACS analysis, L. Tamayo for graphics, and C. Clark, M. Moore, and M. Aguet for useful discussions.

      REFERENCES

        • Beutler B.
        • van Huffel C.
        Science. 1994; 264: 667-668
        • Smith C.A.
        • Farrah T.
        • Goodwin R.G.
        Cell. 1994; 76: 959-962
        • Gruss H.J.
        • Dower S.K.
        Blood. 1995; 85: 3378-3404
        • Krammer P.H.
        • Behrmann I.
        • Daniel P.
        • Dhein J.
        • Debatin K.M.
        Curr. Opin. Immunol. 1994; 6: 279-289
        • Nagata S.
        • Golstein P.
        Science. 1995; 267: 1449-1456
        • Daniel P.T.
        • Krammer P.H.
        J. Immunol. 1994; 152: 5624-5632
        • Zheng L.
        • Fisher G.
        • Miller R.E.
        • Peschon J.
        • Lynch D.H.
        • Lenardo M.J.
        Nature. 1995; 377: 348-351
        • Schall T.J.
        • Lewis M.
        • Koller K.J.
        • Lee A.
        • Rice G.C.
        • Wong G.H.W.
        • Gatanaga T.
        • Granger G.A.
        • Lentz R.
        • Raab H.
        • Kohr W.J.
        • Goeddel D.V.
        Cell. 1990; 61: 361-370
        • Evan G.I.
        • Lewis G.K.
        • Ramsay G.
        • Bishop J.M.
        Mol. Cell. Biol. 1985; 5: 3610-3616
        • O'Reilley D.R.
        • Miller L.K.
        • Luckow V.A.
        Baculovirus Expression Vectors, a Laboratory Manual. Oxford University Press, Oxford1994
        • Ruppert S.
        • Wang E.H.
        • Tijan R.
        Nature. 1993; 362: 175-179
        • Sherwood S.W.
        • Schimke R.T.
        Methods Cell Biol. 1995; 46: 77-97
        • Darzynkiewicz Z.
        • Li X.
        • Gong G.
        Methods Cell Biol. 1994; 41: 15-38
        • Fadok V.A.
        • Voelker D.R.
        • Campbell P.A.
        • Choen J.J.
        • Bratton D.L.
        • Henson P.M.
        J. Immunol. 1992; 148: 2207-2214
        • Koopman G.
        • Reutelingsperger C.P.M.
        • Kuijten G.A.M.
        • Keehnen R.M.J.
        • Pals S.T.
        • van Oers M.H.J.
        Blood. 1994; 84: 1415-1420
        • Moore A.
        • Donahue C.J.
        • Hooley J.
        • Stocks D.L.
        • Bauer K.D.
        • Mather J.P.
        Cytotechnology. 1995; 17: 1-11
        • Kozak M.
        J. Cell Biol. 1991; 115: 887-903
        • Eck M.J.
        • Sprang S.R.
        J. Biol. Chem. 1989; 264: 17595-17605
        • Eck M.J.
        • Ultsch M.
        • Rinderknecht E.
        • de Vos A.M.
        • Sprang S.R.
        J. Biol. Chem. 1992; 267: 2119-2122
        • Yonehara S.
        • Ishii A.
        • Yonehara M.
        J. Exp. Med. 1989; 169: 1747-1756
        • Cohen J.J.
        Adv. Immunol. 1991; 50: 55-85
        • Dhein J.
        • Walczak H.
        • Baumler C.
        • Debatin K.-M.
        • Krammer P.H.
        Nature. 1995; 373: 438-441
        • Ashkenazi A.
        • Marsters S.A.
        • Capon D.J.
        • Chamow S.M.
        • Figari I.S.
        • Pennica D.
        • Goeddel D.V.
        • Palladino M.A.
        • Smith D.H.
        Proc. Natl. Acad. Sci. U. S. A. 1991; 88: 10535-10539
        • Howard O.M.Z.
        • Clouse K.A.
        • Smith C.
        • Goodwin R.G.
        • Farrar W.L.
        Proc. Natl. Acad. Sci. U. S. A. 1993; 90: 2335-2339
        • Raff M.C.
        Nature. 1992; 356: 397-400
        • Steller H.
        Science. 1995; 267: 1445-1449