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Mol. Cell. Biol., 07 1997, 3898-3906, Vol 17, No. 7
OI Sirenko, AK Lofquist, CT DeMaria, JS Morris, G Brewer and JS Haskill
Monocyte adherence results in the rapid transcriptional activation and mRNA
stabilization of numerous mediators of inflammation and tissue repair.
While the enhancer and promoter elements associated with transcriptional
activation have been studied, mechanisms linking adhesion, mRNA
stabilization, and translation are unknown. GROalpha and interleukin-1beta
(IL-1beta) mRNAs are highly labile in nonadhered monocytes but stabilize
rapidly after adherence. GROalpha and IL-1beta transcripts both contain
A+U-rich elements (AREs) in the 3' untranslated region (UTR) which have
been directly associated with rapid mRNA turnover. To determine if the
GROalpha ARE region was recognized by factors associated with mRNA
degradation, we carried out mobility gel shift analyses using a series of
RNA probes encompassing the entire GROalpha transcript. Stable complexes
were formed only with the proximal 3' UTR which contained the ARE region.
The two slower- moving complexes were rapidly depleted following monocyte
adherence but not direct integrin engagement. Deadherence reactivated the
two largest ARE-binding complexes and destabilized IL-1beta transcripts.
Antibody supershift studies demonstrated that both of these ARE RNA-binding
complexes contained AUF1. The formation of these complexes and the
accelerated mRNA turnover are phosphorylation-dependent events, as both are
induced in adherent monocytes by the tyrosine kinase inhibitor genistein
and the p38 MAP kinase inhibitor of IL-1beta translation, SK&F 86002.
These results demonstrate that cell adhesion and deadhesion rapidly and
reversibly modify both cytokine mRNA stability and the RNA- binding
complexes associated with AUF1.
Copyright © 1997, American Society for Microbiology
Adhesion-dependent regulation of an A+U-rich element-binding activity associated with AUF1
Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill 27599-7295, USA.
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