TY - JOUR
T1 - Regulation of eotaxin gene expression by TNF-α and IL-4 through mRNA stabilization
T2 - Involvement of the RNA-binding protein HuR
AU - Atasoy, Ulus
AU - Curry, Stephanie L.
AU - López De Silanes, Isabel
AU - Shyu, Ann Bin
AU - Casolaro, Vincenzo
AU - Gorospe, Myriam
AU - Stellato, Cristiana
PY - 2003/10/15
Y1 - 2003/10/15
N2 - During inflammatory responses, a major posttranscriptional regulation of early response and inflammatory gene expression occurs through modulation of mRNA turnover. We report that two potent inducers of the CC chemokine eotaxin, TNF-α and IL-4, regulate its production in airway epithelial cells by increasing eotaxin mRNA stability. In experiments using the transcriptional inhibitor actinomycin D, eotaxin mRNA half-life was significantly prolonged by cell stimulation with TNF-α or IL-4, with the combination of the two cytokines being the most effective in extending the mRNA half-life. Involvement of the eotaxin 3′ untranslated region in the mRNA-stabilizing effect was tested by transient transfection of a construct expressing a chimeric transcript carrying a serum-inducible β-globin reporter linked to the eotaxin 3′ untranslated region. The half-life of the chimeric mRNA was markedly increased in cells stimulated with TNF-α and IL-4. Evidence that the mRNA-stabilizing protein HuR participated in the cytokine effect was obtained: first, HuR presence in the cytoplasm, believed to be required for HuR-mediated mRNA stabilization, increased in both transformed (BEAS-2B cell line) and primary bronchial epithelial cells following treatment with TNF-α and IL-4. Second, endogenous eotaxin mRNA was found to bind to HuR in vivo, as detected by immunoprecipitation of HuR-containing messenger ribonucleoprotein complexes followed by real-time RT-PCR analysis; such association increased after cell treatment with TNF-α and IL-4. Third, overexpression of HuR in BEAS-2B cells significantly increased the expression of eotaxin mRNA and protein. Our findings implicate mRNA stabilization in the cytokine-mediated increase in eotaxin expression and strongly suggest a role for HuR in this effect.
AB - During inflammatory responses, a major posttranscriptional regulation of early response and inflammatory gene expression occurs through modulation of mRNA turnover. We report that two potent inducers of the CC chemokine eotaxin, TNF-α and IL-4, regulate its production in airway epithelial cells by increasing eotaxin mRNA stability. In experiments using the transcriptional inhibitor actinomycin D, eotaxin mRNA half-life was significantly prolonged by cell stimulation with TNF-α or IL-4, with the combination of the two cytokines being the most effective in extending the mRNA half-life. Involvement of the eotaxin 3′ untranslated region in the mRNA-stabilizing effect was tested by transient transfection of a construct expressing a chimeric transcript carrying a serum-inducible β-globin reporter linked to the eotaxin 3′ untranslated region. The half-life of the chimeric mRNA was markedly increased in cells stimulated with TNF-α and IL-4. Evidence that the mRNA-stabilizing protein HuR participated in the cytokine effect was obtained: first, HuR presence in the cytoplasm, believed to be required for HuR-mediated mRNA stabilization, increased in both transformed (BEAS-2B cell line) and primary bronchial epithelial cells following treatment with TNF-α and IL-4. Second, endogenous eotaxin mRNA was found to bind to HuR in vivo, as detected by immunoprecipitation of HuR-containing messenger ribonucleoprotein complexes followed by real-time RT-PCR analysis; such association increased after cell treatment with TNF-α and IL-4. Third, overexpression of HuR in BEAS-2B cells significantly increased the expression of eotaxin mRNA and protein. Our findings implicate mRNA stabilization in the cytokine-mediated increase in eotaxin expression and strongly suggest a role for HuR in this effect.
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M3 - Article
C2 - 14530362
AN - SCOPUS:0141889091
SN - 0022-1767
VL - 171
SP - 4369
EP - 4378
JO - Journal of Immunology
JF - Journal of Immunology
IS - 8
ER -