Grf40, A Novel Grb2 Family Member, Is Involved in T Cell Signaling

• Project/Area Number: 11670310
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Immunology
• Research Institution: Tohoku University
• Principal Investigator: ASAO Hironobu Graduate School of Medicine, Tohoku University, Associate Professor, 大学院・医学系研究科, 助教授 (80250744)
• Co-Investigator(Kenkyū-buntansha): ISHII Naoto Graduate School of Medicine, Tohoku University, Research Associate, 大学院・医学系研究科, 助手 (60291267)
• Project Period (FY): 1999 – 2000
• Project Status: Completed (Fiscal Year 2000)
• Budget Amount: ¥3,700,000 (Direct Cost: ¥3,700,000); Fiscal Year 2000: ¥1,800,000 (Direct Cost: ¥1,800,000); Fiscal Year 1999: ¥1,900,000 (Direct Cost: ¥1,900,000)
• Keywords: Grf40 / Gads / TCR / Grb2 family / signal transduction

Research Abstract

We molecularly cloned a new Grb2 family member, named Grf40. Expression of Grf40 is predominant in hematopoietic cells, particularly T cells. Grf40 binds tp SLP-76 more tightly than Grb2. Incidentally, Grf40 binds to linker for activation of T cells (LAT) possibly via its SH2 domain. Overexpression of wild-type Grf40 in Jurkat cells induced a significant increase of SLP-76-dependent interleukin (IL)-2 promoter and nuclear factor of activated T cell (NF-AT) activation upon T cell receptor (TCR) stimulation, whereas the C-terminal SH3-deleted Grf40 mutant lacked any recognizable increase in IL-2 promoter activity. Furthermore, the SH2-deleted Grf40 mutant (Grf40-dSH2) led to a marked inhibition of these regulatory activities, the effect of which is apparently stronger than that of the SH2-deleted Grb2 mutant. Our data suggest that Grf40 is an adaptor molecule involved in TCR-mediated signaling through a more efficient interaction than Grb2 with SLP-76 and LAT.To investigate an in vivo function of Grf40, We generated transgenic mice expressing Grf40-dSH2, which is driven by the lck proximal promoter. The total number of thymocytes was profoundly reduced in the transgenic mice, whereas in the double-negative (CD4-CD8-) thymocyte subset, in particular, the CD25+CD44-pre-T cell population was significantly increased. However, CD5 expression, which is mediated by pre-TCR stimulation, was significantly suppressed on the CD4-CD8-thymocytes of the transgenic mice. Furthermore, the SLP-76-dependent signaling was markedly suppressed as well. These data suggest that Grf40 plays an important role in the pre-TCR as well as TCR signaling in thymocytes.

Research Products

• [Publications] Hirosi Asada et al.: "Grf40, A Novel Grb2 Family Member, Is Involved in T cell Signaling through Interaction with SLP-76 and LAT."J.Exp.Med.. 189. 1383-1390 (1999)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Kazu Kikuchi et al.: "Suppression of Thymic Development by the Dominant-negative Form of Gads"Int.Immunol.. (in press).
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Asada, H., Ishii, N., Sasaki, Y., Endo, K., Kasai, H., Tanaka, N., Takeshita, T., Tsuchiya, S., Konno, T.and Sugamura, K.: "Grf40, A Novel Grb2 Family Member, Is Involved in T Cell Signaling through Interaction with SLP-76 and LAT."J.Exp.Med.. Vol.189. 1383-1390 (1999)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Kikuchi, K., Kawasaki, Y., Ishii, N., Sasaki, Y., Asao, H., Takeshita, T., Miyoshi, I., Kasai, N.and Sugamura, K.: "Suppression of Thymic Development by the Dominant-negative Form of Gads."Int.Immunol.. (in press).
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Hirosi Asada et al.: "Grf40, A Novel Grb2 Family Member, Is Involved in T cell Signaling through Interaction with SLP-76 and LAT."J.Exp.Med.. 189. 1383-1390 (1999)
• [Publications] Nobuyuki Tanaka et al.: "Possible Involvement of a Novel STAM-associated Molecule "AMSH" in Interacellular Signal Transduction Mediated by Cytokines."J.Biol.Chem.. 274. 19129-19135 (1999)
• [Publications] Kazuhiro Endo et al.: "STAM2, a new member of the STAM family, binding to the Janus kinases."FEBS Lett.. 477. 55-61 (2000)
• [Publications] Kazu Kikuchi et al.: "Suppression of Thymic Development by the Dominant-negative Form of Gads"Int.Immunol.. (in press).
• [Publications] Mitsuhiro Yamada et al.: "Loss of Hippocampal CA3 Pyramidal Neurons in Mice Lacking STAM1"Mol.Cell.Biol.. (in press).
• [Publications] Hirosi Asada et al.: "Grf40, A Novel Grb2 Family Member, Is Involved in T cell Signaling through Interaction with SLP-76 and LAT"J. Exp. Med.. 189. 1383-1390 (1999)
• [Publications] Nobuyuki Tanaka et al.: "Possible Involvement of a Novel STAM-associated Molecule "AMSH" in Intracellular Signal Transduction Mediated by Cytokines"J. Biol. Chem.. 274. 19129-19135 (1999)