Tumor necrosis factor-alpha mRNA remains unstable and hypoadenylated upon stimulation of macrophages by lipopolysaccharides.
TNF-alpha gene expression is regulated at transcriptional and post-transcriptional levels in mouse macrophages. The post-transcriptional regulation is mediated by the AU-rich element (ARE) located in the TNF-alpha mRNA 3' untranslated region (UTR), which controls its translation and stability. In resting macrophages, the ARE represses TNF-alpha mRNA translation. Activation of macrophages with various agents [for example lipopolysaccharide (LPS), viruses] results in translational derepression, leading to the production of high levels of TNF-alpha. TNF-alpha ARE has also been shown to confer mRNA instability as its deletion from the mouse genome leads to an increase in the TNF-alpha mRNA half-life [Kontoyiannis, D., Pasparakis, M., Pizzaro, T., Cominelli, F. & Kollias, G. (1999) Immunity 10, 387-398]. In this study, we measured the half-life as well as the poly(A) tail length of TNF-alpha mRNA in the course of macrophage activation by LPS. We report that TNF-alpha mRNA is short lived even in conditions of maximal TNF-alpha synthesis. Moreover, TNF-alpha mRNA is hypoadenylated in a constitutive manner. These results reveal that TNF-alpha mRNA rapid turnover does not constitute a regulatory step of TNF-alpha biosynthesis in macrophages and that TNF-alpha mRNA translational activation upon LPS stimulation is not accompanied by a change of poly(A) tail length.
Mijatovic
T
T
Laboratoire de Chimie Biologique IBMM, Université Libre de Bruxelles, Gosselies, Belgium.
Houzet
L
L
Defrance
P
P
Droogmans
L
L
Huez
G
G
Kruys
V
V
D020413:3' Untranslated Regions / Q000235:genetics; D000818:Animals; D002460:Cell Line; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins; D005246:Feedback; D005786:Gene Expression Regulation / Q000187:drug effects; D006207:Half-Life; D006367:HeLa Cells / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D017874:Immediate-Early Proteins; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects* / Q000235:genetics; D008264:Macrophages / Q000187:drug effects*; D051379:Mice; D014176:Protein Biosynthesis; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D051816:Tristetraprolin; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*; D016335:Zinc Fingers
D020413:3' Untranslated Regions; D004268:DNA-Binding Proteins; D017874:Immediate-Early Proteins; D008070:Lipopolysaccharides; D011506:Proteins; D012333:RNA, Messenger; D051816:Tristetraprolin; D014409:Tumor Necrosis Factor-alpha; C497552:ZFP36 protein, human; C497553:Zfp36 protein, mouse