Platelet-derived growth factor induces interleukin-1 receptor gene expression in Balb/c 3T3 fibroblasts

Our previous studies have demonstrated that platelet-derived growth factor (PDGF) modulated cellular responses to interleukin-1 (IL-1). In this communication, we show that PDGF regulates expression of IL-1 receptor (IL-1 R) gene. Treatment of quiescent cultures of Balb/c 3T3 fibroblasts with PDGF produced 20-30-fold stimulation of IL-1 R mRNA with a concomitant increase in cell surface 125I-binding. IL-1 R mRNA accumulation occurred after an initial lag period and with a time course preceding the increase in 125I-IL-1 binding to cells. Induction of IL-1 R mRNA was blocked by inhibitors of protein synthesis, suggesting that a product of a gene expressed immediately after PDGF addition is required for IL-1 R gene expression. These latter data provide evidence for an ordered sequence of expression of PDGF-inducible "immediate early" gene(s) and IL-1 R gene. These results suggest that in connective tissues, PDGF may be an important determinant in initiating and maintaining cellular responses to IL-1. Such responses may have important consequences in the actions of IL-1 under normal and pathological conditions such as arthritis and atherosclerosis.     

Induction of interleukin-2 receptor-alpha gene expression is regulated by post-translational activation of kappa B specific DNA binding proteins

T cell mitogens induce the expression of specific trans-acting DNA binding proteins that in turn regulate the expression of the interleukin-2 receptor-alpha (IL-2R alpha) gene. To investigate whether de novo protein synthesis is required for the activation of these transacting factors and the induced expression of this receptor gene, Jurkat T cells were incubated with various inhibitors of protein synthesis prior to stimulation with phytohemagglutinin and phorbol 12-myristate 13-acetate (PMA). Despite the presence of cycloheximide or anisomycin at concentrations sufficient to block greater than 97% of cellular protein synthesis, phytohemagglutinin and phorbol 12-myristate 13-acetate effectively induced the expression of the IL-2R alpha gene as measured at the mRNA level. Similarly, gel retardation, DNA footprinting, and DNA-protein cross-linking studies revealed that these mitogens induced the activation of two predominant DNA binding proteins (50-55 and 80-90 kDa) in the presence or absence of cycloheximide and anisomycin. Both of these proteins specifically interacted with a kappa B-like binding site present in the IL-2R alpha promoter (-267 to -256) that is requisite for mitogen-induced expression of this receptor gene. These findings support a post-translational mechanism of induction of pre-existing, but inactive, DNA binding proteins which in turn bind to and activate the IL-2R alpha gene.     

IL1HY1: A novel interleukin-1 receptor antagonist gene.

Interleukin-1 is a potent mediator of inflammation, involved in regulating a wide variety of physiological and cellular events. We have identified and characterized a novel member of the human interleukin-1 gene family (IL1HY1). The encoded protein demonstrates significant amino acid homology to the receptor antagonist (IL-1ra) at 52%. The gene was mapped to the long arm of chromosome 2, in close proximity to the IL-1 locus. IL1HY1 message is tightly regulated being most predominantly expressed in the skin, but also detected in the spleen, brain leukocyte, and macrophage cell types. Furthermore, the message can be induced in THP-1 cells by phorbol ester (PMA) and lipopolysaccharide (LPS) treatment.     

IL-1 induces high affinity IL-2 receptor expression of CD4-8- thymocytes

We investigated the role of cytokines for the growth of CD4-8-thymocytes (double negative thymocytes) (DNT) in vitro and found that IL-1-induced IL-2-dependent proliferation of only the IL-2R-positive DNT subpopulation. The presence of IL-1 during the first 18 h of culture was sufficient for an optimal response and suggested that IL-1 induced DNT differentiation. We could indeed show by RNA dot blot analysis that IL-1 stimulated de novo expression of the p55 chain of the IL-2R thus initiating high affinity IL-2 binding and a proliferative response. Because macrophages and epithelial cells in the thymus produce IL-1 we propose that IL-1 is involved in early events during maturation of immature thymocytes.     

Induction of interleukin-2 receptor α-chain gene expression by cytochalasin B and 12-O-tetradecanoylphorbol-13-acetate in T lymphocytes

Abstract. The high affinity form of interleukin-2 receptor (IL-2R) is composed of two subunits; the α (p55) and β (p75). The α chain, unlike the β, is expressed only on activated T lymphocytes. Therefore, high affinity binding of interleukin-2 (IL-2) is controlled by the expression of the IL-2R α-chain. In this study, we examined the effect of cytochalasin B (CB) plus 12-O-tetradecanoylphorbol-13-acetate (TPA) on expression of IL-2 and IL-2R. Northern blot and flow cytometric analysis showed that the IL-2R α-chain was expressed both at mRNA and protein levels. However, IL-2 gene expression was not induced by this treatment. Unlike the cells treated individually with CB or TPA, cells treated with CB plus TPA accumulated IL-2R mRNA at all the times examined. In order to determine the percentage of cells that incorporated tritiated thymidine ([³H]dT) in the presence of IL-2 after treatment with CB plus TPA, autoradiography was carried out. We found that about 11% of the cells were labelled. Because the percentage of labelled cells and cells expressing IL-2R α-chain was relatively low (11% and 9% respectively), perhaps CB plus TPA caused IL-2R expression in only a subset of T cells.     

人白细胞介素2受体(IL-2R)cDNA在哺乳类细胞中表达的初步研究

按DNA-磷酸钙共沉淀法将人白细胞介素2受体(IL-2R)cDNA转染小鼠成纤维细胞L929,经RNA点渍杂交分析、荧光标记IL-2染色和抗Tac(人IL-2受体α链)特异性玫瑰花环试验,均证明转入的IL-2R cDNA在L929细胞中表达,其产物具有结合IL-2和抗Tac抗体的能力。本文还报道了T细胞白血病Jukat细胞和Molt-4等细胞系异常表达IL-2R的结果,并对此作了分析和讨论。     

Interleukin-1 receptor cluster: gene organization of IL1R2, IL1R1, IL1RL2 (IL-1Rrp2), IL1RL1 (T1/ST2), and IL18R1 (IL-1Rrp) on human chromosome 2q

The family of interleukin-1 receptor-like genes currently has six known members. We have constructed a contig of 10 overlapping human PAC clones that covers 530 kb and includes five of the six family members. The termini of the contig were mapped to the interval between D2S373 and D2S176 (chromosome 2q12) by radiation hybrid mapping. The contig contains the genes (cen --> tel), in the order given, for the type II interleukin-1 (IL-1) receptor (IL1R2), the type I IL-1 receptor (IL1R1), the IL-1 receptor-related protein 2 (IL1RL2), T1/ST2/fit-1 (IL1RL1), and the IL-1 receptor-related protein 1, which has recently been shown to be a component of the IL-18 receptor (IL18R1). We show that all the genes are transcribed in the same direction, with IL1R2 being transcribed toward the cluster. The only known family member that is absent from the human contig is the IL-1 receptor accessory protein gene (IL1RAP), which maps to 3q28.