TTP-dependent mRNA decay in LPS-stimulated macrophages

Controlled decay of cytokine and chemokine mRNAs restrains the time and amplitude of inflammatory responses. Tristetraprolin (TTP) binds to AU-rich elements in 3´ untranslated regions of mRNA and targets the bound mRNA for degradation. We have addressed here the function of TTP in balancing the macrophage activation state by a comprehensive analysis of TTP-dependent mRNA decay in LPS-stimulated macrophages from WT and TTP-deficient mice. We compared mRNA stability in LPS-treated BMDMs from WT and TTP-/- mice by microarray-based measurement of the remnant mRNA after transcriptional blockade with actinomycin D (act D). To increase the sensitivity of the mRNA decay profiling we inhibited the LPS-activated p38 MAPK with the specific inhibitor SB203580 since p38 MAPK negatively regulates the mRNA-destabilizing activity of TTP. LPS stimulation was for 3h before addition of act D. RNA was harvested at 0', 45' and 90' thereafter.