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Processing Bodies (processing + body)
Selected AbstractsAnthrax lethal toxin promotes dephosphorylation of TTP and formation of processing bodiesCELLULAR MICROBIOLOGY, Issue 4 2010Edith M. C. Chow Summary Anthrax lethal toxin (LeTx) is composed of protective antigen (PA) and lethal factor (LF) , PA is the receptor-binding moiety and LF is a protease that cleaves mitogen-activated protein kinase kinases (MAPKKs). LeTx subverts the immune response to Bacillus anthracis in several ways, such as downregulating interleukin-8 (IL-8) by increasing the rate of IL-8 mRNA degradation. Many transcripts are regulated through cis -acting elements that bind proteins that either impede or promote degradation. Some of these RNA-binding proteins are regulated by MAPKs and previous work has demonstrated that interfering with MAPK signalling decreases the half-life of IL-8 mRNA. Here, we have localized a segment within the IL-8 3, untranslated region responsible for LeTx-induced transcript destabilization and show that this is caused by inhibition of the p38, ERK and JNK pathways. TTP, an RNA-binding protein involved in IL-8 mRNA decay, became hypophosphorylated in LeTx-treated cells and knock-down of TTP prevented LeTx from destabilizing the IL-8 transcript. Cells that were treated with LeTx exhibited increased localization of TTP to Processing bodies, which are structures that accumulate transcripts targeted for degradation. We furthermore observed that LeTx promoted the formation of Processing bodies, revealing a link between the toxin and a major mRNA decay pathway. [source] Plant stress granules and mRNA processing bodies are distinct from heat stress granulesTHE PLANT JOURNAL, Issue 4 2008Christian Weber Summary Similar to the situation in mammalian cells and yeast, messenger ribonucleo protein (mRNP) homeostasis in plant cells depends on rapid transitions between three functional states, i.e. translated mRNPs in polysomes, stored mRNPs and mRNPs under degradation. Studies in mammalian cells showed that whenever the dynamic exchange of the components between these states is disrupted, stalled mRNPs accumulate in cytoplasmic aggregates, such as stress granules (SGs) or processing bodies (PBs). We identified PBs and SGs in plant cells by detection of DCP1, DCP2 and XRN4, as marker proteins for the 5,,3, mRNA degradation pathway, and eIF4E, as well as the RNA binding proteins RBP47 and UBP1, as marker proteins for stored mRNPs in SGs. Cycloheximide-inhibited translation, stress treatments and mutants defective in mRNP homeostasis were used to study the dynamic transitions of mRNPs between SGs and PBs. SGs and PBs can be clearly discriminated from the previously described heat stress granules (HSGs), which evidently do not contain mRNPs. Thus, the role of HSGs as putative mRNP storage sites must be revised. [source] Mouse hepatitis coronavirus replication induces host translational shutoff and mRNA decay, with concomitant formation of stress granules and processing bodiesCELLULAR MICROBIOLOGY, Issue 9 2007Matthijs Raaben Summary Many viruses, including coronaviruses, induce host translational shutoff, while maintaining synthesis of their own gene products. In this study we performed genome-wide microarray analyses of the expression patterns of mouse hepatitis coronavirus (MHV)-infected cells. At the time of MHV-induced host translational shutoff, downregulation of numerous mRNAs, many of which encode protein translation-related factors, was observed. This downregulation, which is reminiscent of a cellular stress response, was dependent on viral replication and caused by mRNA decay. Concomitantly, phosphorylation of the eukaryotic translation initiation factor 2, was increased in MHV-infected cells. In addition, stress granules and processing bodies appeared, which are sites for mRNA stalling and degradation respectively. We propose that MHV replication induces host translational shutoff by triggering an integrated stress response. However, MHV replication per se does not appear to benefit from the inhibition of host protein synthesis, at least in vitro, since viral replication was not negatively affected but rather enhanced in cells with impaired translational shutoff. [source] | ||||||||||