Transcriptional and posttranscriptional regulation of the interleukin-4 and interleukin-3 genes in human T cells

Abstract

Human T cells were studied with regard to the regulation of interleukin- 4 (IL-4) and IL-3 gene expression. IL-4 and IL-3 mRNA were undetectable in unstimulated T cells. On activation with the lectin concanavalin A (Con A), both IL-4 and IL-3 mRNA were expressed. Accumulation of IL-4 mRNA peaked after 6 to 12 hours, whereas IL-3 mRNA levels peaked after 3 to 6 hours of stimulation with Con A. Nuclear run-on assays showed a low constitutive transcription for both genes. The transcription rates were increased by Con A resulting in a peak for IL-4 after 1 hour (30% increase) and for IL-3 after 3 hours (40% increase) of Con A treatment. mRNA stability studies demonstrated that on activation with Con A both messages decayed with a half-life of approximately 90 minutes. No IL-4 or IL-3 mRNA expression was induced by the protein kinase C activator phorbol myristate acetate (PMA). However, PMA augmented the Con A- induced IL-4 and IL-3 mRNA accumulation. This was shown to be mediated at posttranscriptional level by a large increase in the stability of both messages (t 1/2 > 3 hours). The transcription rate of both genes was also enhanced by Con A+PMA and reached peak levels for IL-4 after 1 hour (90% increase) and for IL-3 after 3 hours (70% increase) of stimulation. Furthermore, it appeared that the induction of IL-4 mRNA was dependent on protein synthesis because cycloheximide (CHX) blocked the Con A- and Con A+PMA-induced expression of IL-4 mRNA. In contrast, CHX inhibited, but failed to completely block, the Con A- and Con A+PMA- induced IL-3 mRNA expression, whereas the expression of both genes was completely blocked by cyclosporine A. With regard to the secretion of IL-4 protein it was shown that it closely follows the accumulation of IL-4 mRNA. Taken together, the data show that expression of the IL-4 and IL-3 genes in human T cells is controlled by different activation pathways that affect the gene regulation at transcriptional and posttranscriptional levels.

Peripheral blood T lymphocytes from asthmatic patients are primed for enhanced expression of interleukin (IL)‐4 and IL‐5 mRNA: associations with lung function and serum IgE

“…It can be speculated that the more mast cells are degranulated (and IL-4 secreted by these mast cells), the less IL-4 is produced by peripheral T lymphocytes as a result of a negative feedback loop induced by mast cell-derived IL-4. This is also suggested by observations in healthy human T lymphocytes, where IL-4 mRNA levels were shown to be down-regulated by IL-4 itself [30].…”

Low‐dose and short‐term cyclosporine treatment in patients with chronic idiopathic urticaria: A clinical and immunological evaluation

“…There was no significant difference between the serum IL-2R levels of control and study patients (P = 0.274). The serum TNF-α levels of the patients in study and control groups 24], respectively (P = 0.001). After CsA therapy, IL-5 was noted to be 114.95 ± 36.61 pg/mL (range, 2.91-281.31) in the study group and this reduction was significant compared to the level before CsA therapy (P = 0.001).…”

“…22 The IL-3, IL-4 and IL-5 lowering effect of CsA was also detected in various studies. [23][24][25][26] In a previous study with CsA therapy for atopic dermatitis, the patients received CsA at a dose of 3.5 mg/kg/day for 3 months. In these patients, IL-2R, CD30 + and IL-4 levels were found to be decreased after CsA therapy.…”

Spontaneous expression of IL-4 mRNA in lymphocytes from children with atopic dermatitis

“…Examination of tbe kinetics of iL-4 mRNA expression in the atopic patients, bowcver, showed constitutive expression of iL-4 mRNA at 0 b and an increased duration of expression for up to 24 h after stimulation. Nuclear run-on assays bave demonstrated tbat accumulation of iL-4 mRNA in normal T cells following in vitro stimulation occurs as a result of botb an increased rate of transcription as well as increased stability of transcripts [29]. The increased constitutive and stimulated iL-4 mRNA expression in the atopic patients could similarly relate to either of these factors.…”

“…Although tbe regulation of iL-4 mRNA expression in atopic patients was different from that of controls, gene transcription did not appear to occur in an unrestricted fasbion. CsA, wbicb bas been sbown to inhibit transcription of IL-4 [29], presumably through inhibition of calcineurin and tbe transcription factor NF-AT [30,31], consistently prevented IL-4 mRNA expression in botb unstimulated and stimulated cultures from atopic subjects, in addition, furtber increased expression of iL-4 mRNA couid be induced after 3 6h by stimulation witb PMA/Ca in vitro, indicating that iL-4 mRNA expression in the atopic patients remained sensitive to in vitro stimuli.…”