title: Systematic identification of regulatory proteins critical for T-cell activation.
abstract: BACKGROUND
  The activation of T cells, mediated by the T-cell receptor (TCR), activates a battery of specific membrane-associated, cytosolic and nuclear proteins. Identifying the signaling proteins downstream of TCR activation will help us to understand the regulation of immune responses and will contribute to developing therapeutic agents that target immune regulation.
  
  
  RESULTS
  In an effort to identify novel signaling molecules specific for T-cell activation we undertook a large-scale dominant effector genetic screen using retroviral technology. We cloned and characterized 33 distinct genes from over 2,800 clones obtained in a screen of 7 x 108 Jurkat T cells on the basis of a reduction in TCR-activation-induced CD69 expression after expressing retrovirally derived cDNA libraries. We identified known signaling molecules such as Lck, ZAP70, Syk, PLC gamma 1 and SHP-1 (PTP1C) as truncation mutants with dominant-negative or constitutively active functions. We also discovered molecules not previously known to have functions in this pathway, including a novel protein with a RING domain (found in a class of ubiquitin ligases; we call this protein TRAC-1), transmembrane molecules (EDG1, IL-10R alpha and integrin alpha2), cytoplasmic enzymes and adaptors (PAK2, A-Raf-1, TCPTP, Grb7, SH2-B and GG2-1), and cytoskeletal molecules (moesin and vimentin). Furthermore, using truncated Lck, PLC gamma 1, EDG1 and PAK2 mutants as examples, we showed that these dominant immune-regulatory molecules interfere with IL-2 production in human primary lymphocytes.
  
  
  CONCLUSIONS
  This study identified important signal regulators in T-cell activation. It also demonstrated a highly efficient strategy for discovering many components of signal transduction pathways and validating them in physiological settings.
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Chu
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Jorge
authors.initials: J
authors.lastname: Pardo
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Haoran
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.|Current address: Exelixis Inc., 170 Harbor Way, South San Francisco, CA 94083, USA.
authors.forename: Connie C
authors.initials: CC
authors.lastname: Li
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Erlina
authors.initials: E
authors.lastname: Pali
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Mary M
authors.initials: MM
authors.lastname: Shen
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Kunbin
authors.initials: K
authors.lastname: Qu
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Simon X
authors.initials: SX
authors.lastname: Yu
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Betty Cb
authors.initials: BC
authors.lastname: Huang
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.|Current address: Exelixis Inc., 170 Harbor Way, South San Francisco, CA 94083, USA.
authors.forename: Peiwen
authors.initials: P
authors.lastname: Yu
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Esteban S
authors.initials: ES
authors.lastname: Masuda
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Molineaux
authors.affiliation: Novartis Pharma AG, S-386.6.25, CH-4002 Basel, Switzerland.
authors.forename: Frank
authors.initials: F
authors.lastname: Kolbinger
authors.affiliation: Novartis Forschungsinstitut GmbH, Brunner Strasse 59, A-1235 Vienna, Austria.
authors.forename: Gregorio
authors.initials: G
authors.lastname: Aversa
authors.affiliation: Novartis Forschungsinstitut GmbH, Brunner Strasse 59, A-1235 Vienna, Austria.
authors.forename: Jan
authors.initials: J
authors.lastname: de Vries
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.
authors.forename: Donald G
authors.initials: DG
authors.lastname: Payan
authors.affiliation: Rigel Pharmaceuticals Inc., 1180 Veterans Blvd., South San Francisco, CA 94080, USA.|Current address: Genentech Inc., 1 DNA Way, South San Francisco, CA 94080, USA.
authors.forename: X Charlene
authors.initials: XC
authors.lastname: Liao
mesh_terms: D015703:Antigens, CD / Q000502:physiology; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology; D045744:Cell Line, Tumor; D005786:Gene Expression Regulation; D005796:Genes / Q000502:physiology; D006801:Humans; D019169:Jurkat Cells / Q000737:chemistry / Q000378:metabolism; D037181:Lectins, C-Type; D008213:Lymphocyte Activation / Q000502:physiology*; D011506:Proteins / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D012107:Research Design; D015398:Signal Transduction / Q000502:physiology; D013601:T-Lymphocytes / Q000502:physiology; D015854:Up-Regulation / Q000502:physiology; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D037181:Lectins, C-Type; D011506:Proteins; D011948:Receptors, Antigen, T-Cell; D000099192:CD69 Antigens