The protein tyrosine kinase Fyn activates transcription from the HIV promoter via activation of NF kappa B-like DNA-binding proteins.
Protein tyrosine kinase p59fyn (Fyn) associates with the TCR-CD3 complex, which suggests that Fyn plays a significant role in the signal transduction involving TCR complex. In addition to cellular genes, viral promoters such as the HIV long terminal repeat (LTR) are also activated upon T cell activation. To elucidate the functional significance of Fyn in the expression of viral promoters, we transfected a Fyn-expression vector together with a reporter plasmid containing the chloramphenicol acetyltransferase gene driven by HIV LTR into a human T cell line, Jurkat. In this assay, Fyn stimulated the promoter in HIV LTR when the transfected cells were treated with both concanavalin A and PMA as an antigen-mimic stimulation. This activation required the intact SH2 domain of Fyn. Mutational analysis of HIV LTR showed that the NF kappa B binding sites were responsible for this effect. Electrophoretic mobility shift assays and UV cross-linking experiments showed that activation of T cells by anti-CD3 antibody induced four kappa B-binding proteins (50, 60, 65 and 100 kDa) in Fyn-overexpressing cells more efficiently than in the parental cells. Our results suggested that Fyn was able to regulate expression of a subset of genes via kappa B-binding proteins upon T cell activation.
Hohashi
N
N
Department of Oncology, University of Tokyo, Japan.
Hayashi
T
T
Fusaki
N
N
Takeuchi
M
M
Higurashi
M
M
Okamoto
T
T
Semba
K
K
Yamamoto
T
T
D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D005786:Gene Expression Regulation; D006678:HIV / Q000235:genetics*; D006801:Humans; D015458:Leukemia, T-Cell; D008969:Molecular Sequence Data; D016328:NF-kappa B / Q000096:biosynthesis / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000187:drug effects*; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000502:physiology; D051076:Proto-Oncogene Proteins c-fyn; D012091:Repetitive Sequences, Nucleic Acid / Q000187:drug effects; D014158:Transcription, Genetic / Q000187:drug effects*; D015533:Transcriptional Activation / Q000187:drug effects; D014407:Tumor Cells, Cultured
D004268:DNA-Binding Proteins; D016328:NF-kappa B; D011518:Proto-Oncogene Proteins; D011505:Protein-Tyrosine Kinases; C494957:FYN protein, human; D051076:Proto-Oncogene Proteins c-fyn