The p38 MAPK Regulates IL-24 Expression by Stabilization of the 3′ UTR of IL-24 mRNA
Figure 6
The 3′ UTR of IL-24 mRNA mediates rapid degradation and p38 MAPK-induced stabilization of a reporter mRNA.
(A) Scheme of IL-24 mRNA and insertion of its 3′ UTR into tet-off vector-expressed β-globin mRNA. The three AUUUA-motifs (indicated by arrows) are displayed. (B) HeLa cells were transfected with plasmids expressing the β-globin mRNA without insertion (β-G) or with the IL-24 3′ UTR inserted (β-G-IL24) and with empty vector or a plasmid expressing constitutively active MKK6 (MKK62E). Total RNA was isolated at the indicated times after stopping transcription with doxycycline (3 µg/ml). mRNA amounts were determined by qRT-PCR (means ± SD of triplicates) and expressed relative to the amount at the time of doxycycline addition ( = 100%). (C) mRNAs from a separate experiment carried out as described for (B) were analyzed by Northern blot with a β-globin antisense probe. Two species of the hybrid mRNA (β-G-IL24 a and b) were detected. Ethidium bromide staining of 28 S rRNA is shown as a loading control. Similar results were obtained in two separate experiments.