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Post‐transcriptional regulation of interleukin‐3: roles of AREs, HuR and p38 (749.5)
Author(s) -
Hernandez Marimar
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.749.5
Subject(s) - jurkat cells , luciferase , transfection , untranslated region , p38 mitogen activated protein kinases , messenger rna , microbiology and biotechnology , three prime untranslated region , cytokine , au rich element , chemistry , t cell , biology , signal transduction , cell culture , immunology , gene , mapk/erk pathway , biochemistry , immune system , genetics
Interleukin‐3 (IL‐3) is a pro‐inflammatory cytokine that is secreted by T‐cells upon stimulation, although its mRNA is constitutively expressed, suggesting that is regulated at this level. Our group has shown that the IL‐3 3’UTR is responsible for repressing its expression, being the Adenosine/Uridine‐Rich Elements (ARE) region mainly responsible for this repression. Chimeric luciferase constructs harboring either wild‐type IL‐3 3’ UTR or different mutations on its ARE region were transfected on Jurkat cells and the reporter activity was measured upon T‐cell stimulation. We observed that when the nonamer ARE is interrupted, the 3’UTR is not able to elicit the same response as the wild type 3’UTR. We carried out EMSAs using protein extracts from Jurkat cells at 6, 12 and 24hrs after activation and identified HuR as an ARE‐Binding Protein able to bind the IL‐3 3’UTR AREs. HeLa cells were co‐transfected with plasmids over‐expressing HuR and the luciferase construct which harbors the IL‐3 3’UTR. Luciferase activity and mRNA levels decreased when HuR was over‐expressed. Since p38 has been shown to increase pro‐inflammatory cytokine secretion and is known to phosphorylate HuR, we assessed its possible role in the regulation of IL‐3. After pretreatment of Jurkat cells with the p38 inhibitor SB202190, IL‐3 mRNA levels were significantly decreased upon T‐cell stimulation suggesting that p38 is indeed involved in the post‐transcriptional regulation of IL‐3. Grant Funding Source : Supported by U54 CA96297; NIGMS MBRS RISE R25GM061838