ELSEVIER Biochimica et Biophysica Acta 1242 (1996) 217-220 BB Biochi~ic~a et Biophysica A~ta Meeting Report Programmed cell death: from development to disease Daniel J. Hoeppner a, Michael O. Hengartner a, David E. Fisher b a Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA b Dana Farber Cancer Institute, Harvard Medical School, 44 Binney St., Boston, MA 02115, USA Accepted 1 December 1995 The first Cold Spring Harbor meeting on the topic of Programmed Cell Death took place from September 20-24, 1995. The meeting provided a forum for the presentation of apoptosis research in a wide diversity of systems rang- ing from primitive development to human disease. Methodologies being applied to the study of programmed death were replete with in vivo manipulations (genetic screens, knockout and transgenic animals), gene cloning approaches (two-hybrid and novel death gene strategies), and in vitro biochemical analyses. Several major themes resounded. One was the constantly growing collection of protein family members playing significant roles in the regulation of apoptosis, either positively or negatively. Another recurring observation was that while gene func- tion and sequence are often conserved, inputs and outputs of apoptosis are often system-specific. Finally, the need for clearer mechanistic information, particularly with regard to the biochemistry of apoptosis, was manifest, although a gradual understanding of at least some of the central players has begun to emerge. 1. Surface receptors as death signals Apoptosis is a particularly attractive mechanism to ac- count for positive and negative selection processes during T cell development, when autoreactive clones are deleted from the immune repertoire. S. Nagata (Osaka Bioscience Institute) described the Fas knockout mouse which dis- plays massive lymphadenopathy and splenomegaly, akin to the phenotypes of Ipr and gld autoimmune mice (which harbor mutations affecting Fas or Fas ligand, respectively). These mice are defective in deletion of peripheral T cells, but not thymic clonal deletion. In contrast, Tak Mak (Amgen Institute, University of Toronto) described the phenotype of mice nullizygous for CD30, a Hodgkin's disease cell surface marker. These mice displayed 10-fold thymic hypertrophy. Interestingly, these thymocytes were profoundly resistant to anti-CD3 induced apoptosis, a mea- 0304-419X/96/$32.00 © 1996 Elsevier Science B.V. All rights reserved SSDI 0304-419X(95)00017-8 sure of thymic negative selection. Thus, apoptosis appears to be regulated via CD30 for thymic selection and via Fas for peripheral T cell deletion. Greater mechanistic detail awaits understanding of T cell stimulatory events, such as B7/CD28 costimulation (L. Boise, University of Chicago), as well as further analysis of signaling events subsequent to receptor:ligand binding. 2. Signal transduction in apoptosis Fas and TNF-alpha receptors are both capable of trig- gering apoptosis and share a cytoplasmic motif termed the 'death domain.' Protein-protein interactions of this potent receptor family have been described by several investiga- tors. Using two hybrid approaches, B. Stanger (Harvard Medical School) described the identification of RIP, a Jurkat cell-derived cDNA clone encoding a death domain as well as an N-terminal putative protein kinase motif. A more systematic biochemical analysis of Fas associated proteins (A. Chinnaiyan, U of Michigan Medical School; and P. Krammer, German Cancer Research Center, Heidel- berg) resulted in the characterization of a Fas-associated Death-Inducing Signaling Complex (DISC) which forms upon oligomerization of the Fas receptor. This complex consists of several (at least four, and probably many more) CAPs, or Cytotoxicity-dependent APO-1 associated pro- teins. Krammer and colleagues identified these factors by co-immunoprecipitation of oligomerized Fas. Chinnaiyan and colleagues identified FADD/MORT-1 in a two-hybrid screen for proteins that interact with the cytoplasmic do- main of Fas. CAP1 and CAP2 are phosphorylated forms of FADD/MORT-1. Both groups demonstrate a requirement of the death domain for DISC formation, and no DISC formation with Fas carrying the Iprcg mutation. The nature of the other CAPS has yet to be determined, but a number of candidate proteins have been identified by yeast two-hybrid screens. For example, K. Chu (Chiron Corp.) presented the identification of a Fas-associated