TRANSMEMBRANE SIGNAL TRANSDUCTION: STRUCTURE, MECHANISMS, REGULATION OF EVOLUTION Organizers: Merl F. Hoekstra, Tony Hunter, Heidi Hamm, Jim Hicks, Tony Pawson, Edward A. Dratz and Alfred Wittinghofer February 6 - 13, 1994; Keystone, Colorado Co-Sponsored by ICOS Corporation and Glaxo Research Institute Plenary Sessions Page February 6 Receptor Signalling: An Overview ..................................................................................................................................................... 198 February 7 Heptahelical Receptor Signalling ........................................................................................................................................................ 198 CA++ and Lipid Signalling Pathways ................................................................................................................................................. 199 Receptor Structure ............................................................................................................................................................................... 199 Regulation of Chromosome Mechanics ............................................................................................................................................... 199 February 8 SHUSH3 ........................ ............................................................. 200 Cell Contact Signalling .. .. 20 1 Receptor Kinases ............ ............................................................. 202 Receptor: G Protein Inter ........................................................................................................................................................ 202 Interferon and Immune C .................................................................................. 202 February 9 RAS/RHO/RAP .. ...... .. ...... .. .. .... ..... .............. ................ .......... ........ .... .... ...................................................................................... 204 Mitogen Activation Protein Kinase Signalling ........................... .. , . Small GTP Binding Protein Regulators ...................................... .. , . February 10 Heterotrimeric G Proteins ................................................................................................................................................................... 206 ..................................................................................... 207 ..................................................................................... 207 .......................................................... 207 ..................................................................................... 208 February 11 Protein Phosphatases .................................................................................................................. Kinase Cascade ............................................................................. February 12 Cell Cycle ............................................................................................................................................................................................ 210 Poster Sessions February 7 Poster Session I (1100-178) ................................................................................................................................................................. 211 February 8 Poster Session I1 (1200-285) ................................................................................................................................................................ 231 February 9 Poster Session 111 (1300-376) ............................................................................................................................................................... 252 February 10 Poster Session IV (1400-475) .............................................................................................................................................................. 272 February 12 Poster Session V (1500-555) ............................................................................... ........................................ 291 Late Abstracts ............................................. .. .305 197 TransmembraneSignal Transduction: Structure, Mechanisms, Regulation and Evolution Receptor Signalling: An Overview I001 HETEROMERIC KINASE RECEPTORS FOR THE TGF-P FAMILY, Joan Massague, Liliana Attisano, Juan Carcamo, Fernando Lopez-Casillas, Francesc Ventura, Frances M. B. Weis, Rotraud Wieser and Jeffrey L. Wrana, Cell Biology and Genetics Program and Howard, Hughes Medical Institute, Memorial Sloan-Kettering Cancer Center, New York, New York 10021 The TGF-p-related cytokines, one of the largest groups of growth and differentiation factors, interact with pairs of membrane proteins known as receptor types I and I1 that constitute a family of transmembrane protein serine/threonine kinases. Although the type I1 receptors for TGF-p, activin and bone morphogenetic proteins bind ligand with high affinity and contain a cytoplasmic signaling structure, most of the evidence available so far indicates that these receptors are unable to signal alone; they require the presence of an appropriate type I receptor with which they form a complex. Moreover, type I receptors require type I1 in order to bind ligand. Various members of the transmembrane serine/threonine kinase family from mammals and Drosophilu have now been identified as type I receptors from TGF-p, activin or BMP. Pairwise Combinations of receptor types I and I1 dictate the binding and signaling properties of the resulting complexes. For example, the TGF-p type I receptor TpR-I and the activin type I receptor ActR-IB bind the corresponding ligands in concert with the respective type I1 receptors, TpR-11 and ActR-11. The kinase domains of TpR-I1 and ActR-I1 are very divergent, but the kinase domains of TpR-I and ActR-IB are highly related and both mediate the same set of responses including cell growth arrest. Another type I receptor, ActR-I (a.k.a. Tsk 7L or SKRI) forms a functional activin receptor complex with ActR-11, and interacts weakly with TGF-p and TpR-11. However, the related receptor TSR-I can bind TGF-p in concert with TpR-I1 and activin in concert with ActR-11, mediating as yet unknown responses. Thus, the TGF-p family receptor structure that is emerging from these studies is that of a complex containing two distantly related transmembrane serine/threonine kinases that cooperate to define the ligand binding and signaling specificity of the complex. This basic structure appears to be conserved from mammals to Drosoplriln. TGF-B access to signaling receptors is controlled by betaglycan (the type 111 receptor), a membrane-anchored proteoglycan whose core protein binds TGF-P. Betaglycan has a dual function: its membrane-anchored form serves to present TGF-p directly to receptor 11, enhancing binding and cell responsiveness to TGF-p. In contrast, the ectodomian of betaglycan released into the medium acts as an antagonist of TGF-p binding to membrane receptors. I002 CYTOKINE SIGNALLING AND TARGET GENES Tadatsugu Taniguchi, Institute for Molecular and Cellular Biology, Osaka University, Suita-shi, Osaka 565, Japan Cytokines regulate cell growth in a positive or negative manner by inducing their respective target genes. We have been focusing on two cytokine systems, the IL-2 and IFN systems. IL-2, one of the best studied cytokines, is a potent growth stimulatory factor for lymphocytes, whereas the IFNs are well known "negative growth factors", which inhibit the growth of various cell types including hematopoietic cells. Recently, a number of cytokine receptors including IL-2 receptor(IL-BR),have been analysed. Many of these receptors shave significant homology and constitute a novel family of receptors, characterized by four conserved cysteins and the sequence WSXWS (the WS motif). One interesting feature of this new cytokine receptor family is that its members lack the intrinsic proteln tyrosine kinase domain that is the hall mark of other growth factor receptors. The IL-2R is unique in that it is made up of at least three distinct membrane components: the a chain (IL-2Ra1, the P chain (IL-2RP1, and the ychain (IL-2R.O. We and others have provided evidence for the requirement of the cytoplasmic regions of IL-2RP and IL-2y, but not IL-2Ra, in the IL-2-induced signalling to cell interior. The IL-2RP cham has been shown to interact, both physically and functionally, with the nonreceptor tyrosine kinase Src family members (p5dck,p5gfYn, p53156Iy"). Likewise, other members of the cytokine receptor family seem to utilize another nonreceptor tyrosine kinase members. We have identified several target genes which would mediate IL-%induced cell proliferation of a hematopoietic cell line. Evidence suggests that the IL-ZRP-Src kinase pathway is linked to p21ras and subsequently to c-fos, c-jun activation. On the other hand, another signalling pathway (s)emanating from IL-2RP. IL-2Ry heterodimer, but not linked to the Src kinase pathway, leads to activation of genes such asc-myc, bcl-2 and others, followed bp the progression of the cell cycle. We will present our recent results on the role of these target genes in cell growth control. During the study of the IFN system regulation, we identified two transcription factors, IRF-1 (activator) and IRF-2 (repressor). IRF-1 is IFN-inducible and evidence suggests that IRF-1 is in fact a target gene critical for the IFN functioning as negative regulator