Grb3-3 is up-regulated in HIV-1-infected T-cells and can potentiate cell activation through NFATc.
The MAPK pathway is required for T-cell activation; however, its role in modulating T-cell function following human immunodeficiency virus type 1 (HIV-1) infection is poorly understood. In this report, we investigated whether Grb3-3, an isoform of the Grb2 (growth factor receptor-bound protein-2) adaptor molecule that is associated with the MAPK pathway, could be involved. We found that Grb3-3, but not its isoform Grb2, is markedly up-regulated in CD4(+) peripheral blood mononuclear cells derived from either in vitro HIV-1-infected cultures or HIV-1-infected human subjects. Analysis of HIV-1 gene products indicated that Tat and Nef, both of which have been implicated in modulating T-cell function, can independently induce expression of Grb3-3. By using NFAT/AP-1, AP-1, or NFAT reporter assays, we found that Grb3-3 can potentiate NFAT (but not AP-1) promoter activity in Jurkat T-cells upon engagement of the T-cell receptor and CD28 co-receptor. In addition, potentiation of NFAT by Grb3-3 is substantially suppressed by MEKK1, a kinase that may play an important role in retaining NFAT in the cytoplasm, and by cyclosporin A. Finally, we also found that Grb3-3 potentiates HIV-1 long terminal (LTR) repeat promoter activity following T-cell receptor stimulation, an effect that can be largely suppressed by cyclosporin A. Taken together, this study indicates that Grb3-3 is a cellular factor that can be up-regulated by HIV-1. In addition, Grb3-3 can also function as a positive factor for T-cell activation and, in doing so, may aid in establishing an intracellular environment that can optimally support HIV-1 replication.
Li
X
X
Departments of Cancer Immunology and AIDS and Medicine, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts 02115, USA.
Multon
M C
MC
Henin
Y
Y
Schweighoffer
F
F
Venot
C
C
Josef
J
J
Zhou
C
C
LaVecchio
J
J
Stuckert
P
P
Raab
M
M
Mhashilkar
A
A
Tocque
B
B
Marasco
W A
WA
D048868:Adaptor Proteins, Signal Transducing; D000328:Adult; D000911:Antibodies, Monoclonal / Q000378:metabolism; D015153:Blotting, Western; D018106:CD28 Antigens / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism / Q000821:virology; D002467:Cell Nucleus / Q000378:metabolism; D016572:Cyclosporine / Q000494:pharmacology; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005260:Female; D051380:GRB2 Adaptor Protein; D015693:Gene Products, nef / Q000378:metabolism; D015696:Gene Products, tat / Q000378:metabolism; D015658:HIV Infections / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology; D019169:Jurkat Cells; D007963:Leukocytes, Mononuclear / Q000821:virology; D008156:Luciferases / Q000378:metabolism; D048728:MAP Kinase Kinase Kinase 1; D020935:MAP Kinase Signaling System; D008297:Male; D008875:Middle Aged; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction; D020079:Terminal Repeat Sequences; D013997:Time Factors; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D015854:Up-Regulation; D054311:nef Gene Products, Human Immunodeficiency Virus; D054322:tat Gene Products, Human Immunodeficiency Virus
D048868:Adaptor Proteins, Signal Transducing; D000911:Antibodies, Monoclonal; D018106:CD28 Antigens; D004268:DNA-Binding Proteins; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; D015693:Gene Products, nef; D015696:Gene Products, tat; D007166:Immunosuppressive Agents; D050778:NFATC Transcription Factors; D009687:Nuclear Proteins; D020033:Protein Isoforms; D011506:Proteins; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D054311:nef Gene Products, Human Immunodeficiency Virus; D054322:tat Gene Products, Human Immunodeficiency Virus; D016572:Cyclosporine; D008156:Luciferases; D017346:Protein Serine-Threonine Kinases; D048728:MAP Kinase Kinase Kinase 1; C482576:MAP3K1 protein, human