Characterization of the human Fc gamma RIIB gene promoter: human zinc-finger proteins (ZNF140 and ZNF91) that bind to different regions function as transcription repressors

in International Immunology (2001), 13(8), 1075-84

Expression of the human low-affinity Fc receptors for IgG (human Fc gamma RII) is differentially regulated. We report here the characterization of the promoter structure of the human Fc gamma RIIB gene ... [more ▼]

Expression of the human low-affinity Fc receptors for IgG (human Fc gamma RII) is differentially regulated. We report here the characterization of the promoter structure of the human Fc gamma RIIB gene and the isolation of the promoter region-binding proteins by a yeast one-hybrid assay. The minimal 154-bp region upstream from the transcription start site of the human Fc gamma RIIB gene was shown to possess promoter activity in a variety of cells. An electrophoretic mobility shift assay indicated that multiple nuclear factors in cell extracts bind to the two regions [F2-3 (-110 to -93) and F4-3 (-47 to -31)] of the human Fc gamma RIIB gene promoter. Mutation analysis indicated that GGGAGGAGC (-105 to -97) and AATTTGTTTGCC (-47 to -36) sequences are responsible for binding to nuclear factors respectively. By using GGGAGGAGC and AATTTGTTTGCC as bait sequences, we cloned two zinc-finger proteins (ZNF140 and ZNF91) that bind to the F2-3 and F4-3 regions within the promoter of the human Fc gamma RIIB gene respectively. When the ZNF140 and ZNF91 were transfected with reporter plasmid, both showed repressor activity with additive effects. Thus, these results indicate that these cloned ZNF140 and ZNF91 proteins function as repressors for the human Fc gamma RIIB transcription. [less ▲]

Reciprocal regulation of protein tyrosine kinases p56lck and p59fyn, and altered tyrosine phosphorylation in murine AIDS.

in International Immunology (1998), 10(10), 1473-80

Murine AIDS (MAIDS), caused by a defective murine leukemia virus, is a severe lymphoproliferative disease associated with profound immunodeficiency and increased susceptibility to opportunistic infections ... [more ▼]

Murine AIDS (MAIDS), caused by a defective murine leukemia virus, is a severe lymphoproliferative disease associated with profound immunodeficiency and increased susceptibility to opportunistic infections. Most subsets of lymphocytes, including CD4+ and CD8+ T cells, are refractory to mitogen stimulation. As a first step to examine proximal signal transduction in the infected mice, Western and Northern blot analyses were performed, and showed that p56lck is dramatically decreased at the protein as well as the mRNA level in the lymph nodes (LN). In contrast, p59(fyn) and its mRNA were slightly increased in the LN of the same mice. Similar results were obtained with purified T cells. Interestingly, the thymus of the infected animals did not show any abnormality regarding p56(lck) or p59(fyn). Tyrosine phosphorylation was constitutively increased in the infected mice and was barely amplified by anti-CD3 mAb stimulation. A similar pattern was observed when tyrosine phosphorylation was selectively examined at the level of ZAP-70. Our results suggest that a reciprocal regulation of p56(lck) and p59(fyn) protein tyrosine kinases, previously described in various models of anergy, could also be involved in the pathogenesis of MAIDS. [less ▲]

Analysis by in Situ Hybridization of Cytokine Mrna Expression in the Murine Developing Thymus

in International Immunology (1994), 6(10), 1613-9

We have used in situ hybridization to investigate the expression of IL-1, IL-2, IL-4, IL-6 and IFN-gamma genes by thymic cells during fetal development in mice. Two waves of mRNAs were detected in thymic ... [more ▼]

We have used in situ hybridization to investigate the expression of IL-1, IL-2, IL-4, IL-6 and IFN-gamma genes by thymic cells during fetal development in mice. Two waves of mRNAs were detected in thymic cells for IL-1 at days 16 and 19 of gestation, for IL-2 at days 14 and 18, and for IL-4 at days 14 and 16. Three peaks for IL-6 were observed at days 13, 17 and around birth. Finally, only one peak of cells positive for IFN-gamma was detected. Whereas cells positive for IL-1 were generally grouped and more often localized in the external area of the thymus, the other positive cells were isolated and evenly distributed in the thymus. Our results illustrated the presence of cytokine transcripts in the developing thymus following a developmentally controlled sequence and support the hypothesis that cytokines could play a role in T cell development. [less ▲]