Interleukin-9 and its receptor: involvement in mast cell differentiation and T cell oncogenesis.

Interleukin-9 (IL-9) is a multifunctional cytokine produced by activated TH2 clones in vitro and during TH2-like T cell responses in vivo. The IL-9 receptor is a member of the hemopoietin receptor superfamily and interacts with the gamma chain of the IL-2 receptor for signal transduction. Various observations indicate that IL-9 is actively involved in mast cell responses by inducing the proliferation and differentiation of these cells. The role of IL-9 in T cell responses is less clear. Although freshly isolated normal T cells do not respond to IL-9, this cytokine induces the proliferation of murine T cell lymphomas in vitro and in vivo overexpression of IL-9 results in the development of thymic lymphomas. In the human, the existence of an IL-9-mediated autocrine loop has been suggested for some malignancies such as Hodgkin's disease. Other potential biological targets for IL-9 include B lymphocytes, hematopoietic progenitors, and immature neuronal cell lines

IL-9 induces expression of granzymes and high-affinity IgE receptor in murine T helper clones.

Interleukin 9 (IL-9) is a TH2 cytokine that has been shown to promote the antigen-independent growth of some mouse T helper clones. To characterize the specificity of IL-9-mediated T cell activation, we used a murine T cell clone that could grow with either IL-9 or IL-2. After differential hybridization of a cDNA library, we isolated three genes that were expressed preferentially in the presence of IL-9. Two of them correspond respectively to granzyme A and granzyme B, two proteases expressed by activated T cells. By Northern blot hybridization and functional assays, we found that IL-9 induced the expression of granzyme B in several T cell clones as well as in mast cell lines. In addition, other proteases such as the mouse mast cell proteases were also found to be expressed by IL-9-activated T cell clones. The third IL-9-induced cDNA corresponds to the alpha-chain of the high-affinity receptor for IgE. Several T cell clones expressed this IgE receptor mRNA and were able to bind IgE with high affinity. Taken together, our results indicate that IL-9 induces a mast cell-like phenotype in T cell clones

Expression cloning of the murine and human interleukin 9 receptor cDNAs.

Interleukin 9 (IL-9) is a T-cell-derived lymphokine that induces the proliferation of various lymphoid and hemopoietic cells. A cDNA clone encoding the murine IL-9 receptor was isolated by expression cloning in COS cells and screening with 125I-labeled IL-9. Transient expression of this cDNA produced high-affinity binding sites for IL-9. The predicted 52-kDa protein contains a putative signal peptide and a typical transmembrane domain. A cDNA for the human homologue was isolated by cross-hybridization. Transfection of this cDNA in a murine T-cell clone conferred responsiveness to human IL-9. Sequence analysis revealed that the IL-9 receptor belongs to the recently described hematopoietin receptor super-family and is expressed in membrane-bound and soluble forms

The Il-9 Receptor Gene (il9r) - Genomic Structure, Chromosomal Localization in the Pseudoautosomal Region of the Long Arm of the Sex-chromosomes, and Identification of Il9r Pseudogenes At 9qter, 10pter, 16pter, and 18pter

Cosmids containing the human IL-9 receptor (R) gene (IL9R) have been isolated from a genomic library using the IL9R cDNA as a probe. We have shown that the human IL9R gene is composed of 11 exons and 10 introns, stretching over similar to 17 kb, and is located within the pseudoautosomal region of the Xq and Yq chromosome, in the vicinity of the telomere. Analysis of the 5' flanking region revealed multiple transcription initiation sites as well as potential binding motifs for AP1, AP2, AP3, Sp1, and NF-kB, although this region lacks a TATA box. Using the human IL9R cosmid as a probe to perform fluorescence in situ hybridization, additional signals were identified in the subtelomeric regions of chromosomes 9q, 10p, 16p, and 18p. IL9R homologs located on chromosomes 9 and 18 were partially characterized, while those located on chromosomes 16 and 10 were completely sequenced. Although they are similar to the IL9R gene (similar to 90% identity), none of these copies encodes a functional receptor: none of them contains sequences homologous to the 5' flanking region or exon 1 of the IL9R gene, and the remaining ORFs have been inactivated by various point mutations and deletions. Taken together, our results indicate that the IL9R. gene is located at Xq28 and Yq12, in the long arm pseudoautosomal region, and that four IL9R pseudogenes are located on 9q34, 10p15, 16p13.3, and 18p11.3, probably dispersed as the result of translocations during evolution. (C) 1995 Academic Press, Inc

RNAi-mediated oncogene silencing confers resistance to crown gall tumorigenesis

Crown gall disease, caused by the soil bacterium Agrobacterium tumefaciens, results in significant economic losses in perennial crops worldwide. A. tumefaciens is one of the few organisms with a well characterized horizontal gene transfer system, possessing a suite of oncogenes that, when integrated into the plant genome, orchestrate de novo auxin and cytokinin biosynthesis to generate tumors. Specifically, the iaaM and ipt oncogenes, which show ≈90% DNA sequence identity across studied A. tumefaciens strains, are required for tumor formation. By expressing two self-complementary RNA constructions designed to initiate RNA interference (RNAi) of iaaM and ipt, we generated transgenic Arabidopsis thaliana and Lycopersicon esculentum plants that are highly resistant to crown gall disease development. In in vitro root inoculation bioassays with two biovar I strains of A. tumefaciens, transgenic Arabidopsis lines averaged 0.0–1.5% tumorigenesis, whereas wild-type controls averaged 97.5% tumorigenesis. Similarly, several transformed tomato lines that were challenged by stem inoculation with three biovar I strains, one biovar II strain, and one biovar III strain of A. tumefaciens displayed between 0.0% and 24.2% tumorigenesis, whereas controls averaged 100% tumorigenesis. This mechanism of resistance, which is based on mRNA sequence homology rather than the highly specific receptor–ligand binding interactions characteristic of traditional plant resistance genes, should be highly durable. If successful and durable under field conditions, RNAi-mediated oncogene silencing may find broad applicability in the improvement of tree crop and ornamental rootstocks