Project description:Tristetraprolin (TTP) is a tandem CCCH zinc finger protein that was identified through its rapid induction by mitogens in fibroblasts. Studies of TTP-deficient mice, and cells derived from them, showed that TTP could bind to certain AU-rich elements in mRNAs, leading to increases in the rates of mRNA deadenylation and destruction. Known physiological target mRNAs for TTP include tumor necrosis factor alpha (TNF), granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin 2 beta (IL2 beta). Here we used microarray analysis of RNA from wild-type and TTP-deficient fibroblast cell lines to identify transcripts with different decay rates, after serum stimulation and actinomycin D treatment. Of 250 mRNAs apparently stabilized in the absence of TTP, 23 contained conserved TTP binding sites; 10 of these were shown by secondary analyses to be stabilized. The most dramatically affected transcript encoded the protein Ier3, recently implicated in the physiological control of blood pressure. The Ier3 transcript contained several conserved TTP binding sites that could bind TTP directly, and conferred TTP sensitivity to the mRNA in cell transfection studies. These studies have identified several new, physiologically relevant TTP target transcripts in fibroblasts; these target mRNAs encode proteins from a variety of functional classes. Keywords: mRNA degradation, time course, knockout experiment
Project description:Tristetraprolin (TTP) is a tandem CCCH zinc finger protein that was identified through its rapid induction by mitogens in fibroblasts. Studies of TTP-deficient mice, and cells derived from them, showed that TTP could bind to certain AU-rich elements in mRNAs, leading to increases in the rates of mRNA deadenylation and destruction. Known physiological target; mRNAs for TTP include tumor necrosis factor alpha (TNF), granulocyte macrophage colony stimulating factor (GM-CSF) and interleukin 2 beta (IL2 beta). Here we used microarray analysis of RNA from wild-type and TTP-deficient fibroblast cell lines to identify transcripts with different decay rates, after serum stimulation and actinomycin D treatment. Of 250 mRNAs apparently stabilized in the absence of TTP, 23 contained conserved TTP binding sites; 10 of these were shown by secondary analyses to be stabilized. The most dramatically affected transcript encoded the protein Ier3, recently implicated in the physiological control of blood pressure. The Ier3 transcript contained several conserved TTP binding sites that could bind TTP directly, and conferred TTP sensitivity to the mRNA in cell transfection studies. These studies have identified several new, physiologically relevant TTP target transcripts in fibroblasts; these target mRNAs encode proteins from a variety of functional classes. Experiment Overall Design: Cell lines were derived from mouse embryonic fibroblast (MEF) cultures from littermate E14.5 embryos (for Zfp36 +/+ and -/- cells). MEFs were maintained at 37o C (5% CO2) in DMEM containing 10% FBS, 100 Experiment Overall Design: U/ml penicillin, 100 μg/ml streptomycin and 2 mM L-glutamine. When the cells had reached approximately 70-90 % confluence, they were trypsinized and diluted 2-50 fold in the same medium, based on morphology and growth rate, such that they would reach near confluence in 3-4 days when subcultured. Experiment Overall Design: Five identical experiments involving sequential serum deprivation, serum stimulation and actinomycin D treatment were performed on five different days; each experiment involved simultaneous identical experiments with the WT and KO cell lines. In each experiment, the cells were serum deprived for 16h, and a sample was taken at that point as a serum-deprived control. The cells were then stimulated by 10% FBS for Experiment Overall Design: 90 min and another sample taken, after which 5μg/ml actinomycin D was added; samples for RNA analysis were then removed at 30, 60, 90 and 120 min after actinomycin D treatment. In all experiments, each sample represented three combined 100 mm dishes of cells.
Project description: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.
Project description:Tristetraprolin (TTP) binds to specific AU-rich elements in the 3'UTR of certain transcripts and regulates post-transcriptional gene expression by increasing the rate of mRNA turnover. In this study, we evaluated the effects of TTP deficiency on the overall gene expression of spleen tissue, in order to discover tissue specific targets of TTP under normal physiologic conditions. We utilized "Triple KO" (Zfp36-/-/TNFR1-/-/TNFR2-/-) mice that are deficient in TTP and two TNF receptors and compared the transcriptomic changes to "Double KO" (TNFR1-/-/TNFR2-/-) and WT mice. Spleen mRNA from four WT, four "Double KO", and four "Triple mice" was subjected to RNA-Seq in two phases. All the animals used in this study were males between the ages of 12-14 weeks and were on a mixed (75% C57BL/6NTac, 25% 129/SVEV) background.
Project description:Precise control of mRNA decay is fundamental for robust yet not exaggerated inflammatory responses to pathogens. Parameters determining the specificity and extent of mRNA degradation within the entire inflammation-associated transcriptome remain incompletely understood. Using transcriptome-wide high resolution occupancy assessment of the mRNA-destabilizing protein TTP, a major inflammation-limiting factor, we qualitatively and quantitatively characterize TTP binding positions and functionally relate them to TTP-dependent mRNA decay in immunostimulated macrophages. We identify pervasive TTP binding with incompletely penetrant linkage to mRNA destabilization. A necessary but not sufficient feature of TTP-mediated mRNA destabilization is binding to 3â untranslated regions (UTRs). Mapping of binding positions of the mRNA-stabilizing protein HuR in activated macrophages revealed that TTP and HuR binding sites in 3â UTRs occur mostly in different transcripts implicating only a limited co-regulation of inflammatory mRNAs by these proteins. Remarkably, we identify robust and widespread TTP binding to introns of stable transcripts. Nuclear TTP is associated with spliced-out introns and maintained in the nucleus throughout the inflammatory response. Our study establishes a functional annotation of binding positions dictating TTP-dependent mRNA decay in immunostimulated macrophages. The findings allow navigating the transcriptome-wide landscape of RNA elements controlling inflammation. RNA-Seq of RNA isolated from murine bone marrow derived macrophages (WT or TTP-deficient) stimulated for 6 h with LPS
Project description:Tristetraprolin (TTP) binds to specific AU-rich elements in the 3'UTR of certain transcripts and regulates post-transcriptional gene expression by increasing the rate of mRNA turnover. In this study, we evaluated the effects of TTP deficiency on the overall gene expression of spleen tissue, in order to discover tissue specific targets of TTP under normal physiologic conditions. We utilized "Triple KO" (Zfp36-/-/TNFR1-/-/TNFR2-/-) mice that are deficient in TTP and two TNF receptors and compared the transcriptomic changes to "Double KO" (TNFR1-/-/TNFR2-/-) and WT mice. Spleen mRNA from four WT, four "Double KO", and four "Triple mice" was subjected to RNA-Seq in two phases. All the animals used in this study were males between the ages of 12-14 weeks and were on a mixed (75% C57BL/6NTac, 25% 129/SVEV) background. Examination of splenic gene expression difference between "Triple KO"-WT and "double KO"-WT data sets
Project description: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.
Project description:RNA-binding proteins (RBPs) facilitate post-transcriptional control of eukaryotic gene expression at multiple levels. The RBP tristetraprolin (TTP/Zfp36) is a signal-induced phosphorylated anti-inflammatory protein guiding unstable mRNAs of pro-inflammatory proteins for degradation and preventing translation. Using iCLIP, we have identified numerous mRNA targets bound by wild-type TTP and by a non-MK2-phosphorylatable TTP mutant (TTP-AA) in 1h LPS-stimulated macrophages and correlated their interaction with TTP to changes at the level of mRNA abundance and translation in a transcriptome-wide manner. The close similarity of the transcriptome of TTP-deficient and TTP-expressing macrophages upon short LPS stimulation suggested an effective inactivation of TTP by MK2 under these conditions whereas retained RNA-binding capacity of TTP-AA to 3’UTRs caused profound changes in the transcriptome and translatome, altered NF-κB-activation and induced cell death. Increased TTP binding to the 3'UTR of feedback inhibitor mRNAs, such as Ier3, Dusp1 or Tnfaip3, in the absence of MK2-dependent TTP neutralization resulted in a strong reduction of their protein synthesis contributing to the deregulation of the NF-κB-signaling pathway. Taken together, our study uncovers a role for TTP in NF-κB-signaling and highlights the importance of fine-tuned TTP activity-regulation by MK2 in order to control feedback signaling during the inflammatory response.
Project description:RNA-binding proteins (RBPs) facilitate post-transcriptional control of eukaryotic gene expression at multiple levels. The RBP tristetraprolin (TTP/Zfp36) is a signal-induced phosphorylated anti-inflammatory protein guiding unstable mRNAs of pro-inflammatory proteins for degradation and preventing translation. Using iCLIP, we have identified numerous mRNA targets bound by wild-type TTP and by a non-MK2-phosphorylatable TTP mutant (TTP-AA) in 1h LPS-stimulated macrophages and correlated their interaction with TTP to changes at the level of mRNA abundance and translation in a transcriptome-wide manner. The close similarity of the transcriptome of TTP-deficient and TTP-expressing macrophages upon short LPS stimulation suggested an effective inactivation of TTP by MK2 under these conditions whereas retained RNA-binding capacity of TTP-AA to 3’UTRs caused profound changes in the transcriptome and translatome, altered NF-κB-activation and induced cell death. Increased TTP binding to the 3'UTR of feedback inhibitor mRNAs, such as Ier3, Dusp1 or Tnfaip3, in the absence of MK2-dependent TTP neutralization resulted in a strong reduction of their protein synthesis contributing to the deregulation of the NF-κB-signaling pathway. Taken together, our study uncovers a role for TTP in NF-κB-signaling and highlights the importance of fine-tuned TTP activity-regulation by MK2 in order to control feedback signaling during the inflammatory response.
Project description:RNA-binding proteins (RBPs) facilitate post-transcriptional control of eukaryotic gene expression at multiple levels. The RBP tristetraprolin (TTP/Zfp36) is a signal-induced phosphorylated anti-inflammatory protein guiding unstable mRNAs of pro-inflammatory proteins for degradation and preventing translation. Using iCLIP, we have identified numerous mRNA targets bound by wild-type TTP and by a non-MK2-phosphorylatable TTP mutant (TTP-AA) in 1h LPS-stimulated macrophages and correlated their interaction with TTP to changes at the level of mRNA abundance and translation in a transcriptome-wide manner. The close similarity of the transcriptome of TTP-deficient and TTP-expressing macrophages upon short LPS stimulation suggested an effective inactivation of TTP by MK2 under these conditions whereas retained RNA-binding capacity of TTP-AA to 3’UTRs caused profound changes in the transcriptome and translatome, altered NF-κB-activation and induced cell death. Increased TTP binding to the 3'UTR of feedback inhibitor mRNAs, such as Ier3, Dusp1 or Tnfaip3, in the absence of MK2-dependent TTP neutralization resulted in a strong reduction of their protein synthesis contributing to the deregulation of the NF-κB-signaling pathway. Taken together, our study uncovers a role for TTP in NF-κB-signaling and highlights the importance of fine-tuned TTP activity-regulation by MK2 in order to control feedback signaling during the inflammatory response.