Plant stress granules and mRNA processing bodies are distinct from heat stress granules.
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.
Weber
Christian
C
Department of Molecular Cell Biology, Johann Wolfgang Goethe-University Frankfurt, Max von Laue Strasse 9, 60438 Frankfurt, Germany.
Nover
Lutz
L
Fauth
Markus
M
D017360:Arabidopsis / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000378:metabolism; D002478:Cells, Cultured; D003513:Cycloheximide / Q000494:pharmacology; D003594:Cytoplasmic Granules / Q000378:metabolism*; D004722:Endoribonucleases / Q000378:metabolism; D039561:Eukaryotic Initiation Factor-4E / Q000378:metabolism; D005095:Exoribonucleases / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D011132:Polyribosomes / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects; D011523:Protoplasts / Q000378:metabolism; D020871:RNA Stability; D016601:RNA-Binding Proteins / Q000378:metabolism; D012261:Ribonucleoproteins / Q000378:metabolism*; D013312:Stress, Physiological
D029681:Arabidopsis Proteins; D039561:Eukaryotic Initiation Factor-4E; D010940:Plant Proteins; C417027:RBP47 protein, Nicotiana plumbaginifolia; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C407741:UBP1 protein, plant; C418137:Xrn1 protein, plant; C026452:messenger ribonucleoprotein; D003513:Cycloheximide; D004722:Endoribonucleases; D005095:Exoribonucleases; C518493:Dcp1 protein, Arabidopsis; C518494:Dcp2 protein, Arabidopsis