Nuclear bodies and compartmentalization of pre-mRNA splicing factors in higher plants.
We studied the fine structural organization of nuclear bodies in the root meristem during germination of maize and Arabidopsis thaliana using electron microscopy (EM). Cajal bodies (CBs) were observed in quiescent embryos and germinating cells in both species. The number and distribution of CBs were investigated. To characterize the nuclear splicing domains, immunofluorescence labelling with antibodies against splicing factors (U2B" and m3G-snRNAs) and in situ hybridisation (with U1/U6 antisense probes) were performed combined with confocal microscopy. Antibodies specific to the Arabidopsis SR splicing factor atRSp31 were produced. AtRSp31 was detected in quiescent nuclei and in germinating cells. This study revealed an unexpected speckled nuclear organization of atRSp31 in root epidermal cells where micro-clusters of interchromatin granules were also observed by EM. Therefore, we examined the distribution of green fluorescent protein (GFP)-tagged atRSp31 in living cells after Agrobacterium -mediated transient expression. When expressed transiently, atRSp31-GFP exhibited a speckled distribution in leaf cells. Treatments with alpha-amanitin, okadaic acid, staurosporine or heat shock induced the speckles to reorganize. Furthermore, we generated stable Arabidopsis transgenics expressing atRSp31-GFP. The distribution of the fusion protein was identical to that of endogenous atRSp31. Three-dimensional time-lapse confocal microscopy showed that speckles were highly dynamic domains over time.
Docquier
Sarah
S
Laboratory of Plant Cell Biology, Department of Life Sciences, University of Liège, Bld du Rectorat, 27 Sart Tilman, 4000 Liège, Belgium.
Tillemans
Vinciane
V
Deltour
Roger
R
Motte
Patrick
P
D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000276:immunology / Q000378:metabolism; D001324:Autoantigens; D002451:Cell Compartmentation; D020541:Coiled Bodies / Q000378:metabolism* / Q000648:ultrastructure*; D049452:Green Fluorescent Proteins; D007150:Immunohistochemistry; D008164:Luminescent Proteins; D018519:Meristem / Q000166:cytology* / Q000378:metabolism*; D010940:Plant Proteins / Q000276:immunology / Q000378:metabolism; D030821:Plants, Genetically Modified; D012322:RNA Precursors / Q000276:immunology / Q000378:metabolism*; D012326:RNA Splicing / Q000276:immunology / Q000502:physiology*; D016601:RNA-Binding Proteins / Q000276:immunology / Q000378:metabolism; D011994:Recombinant Proteins; D017413:Ribonucleoprotein, U2 Small Nuclear / Q000276:immunology / Q000378:metabolism; D017411:Ribonucleoproteins, Small Nuclear; D000068103:Serine-Arginine Splicing Factors; D017381:Spliceosomes / Q000276:immunology / Q000378:metabolism; D003313:Zea mays; D055517:snRNP Core Proteins
D029681:Arabidopsis Proteins; D001324:Autoantigens; D008164:Luminescent Proteins; D010940:Plant Proteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; C103793:RSp31 protein, Arabidopsis; D011994:Recombinant Proteins; D017413:Ribonucleoprotein, U2 Small Nuclear; D017411:Ribonucleoproteins, Small Nuclear; D055517:snRNP Core Proteins; D049452:Green Fluorescent Proteins; D000068103:Serine-Arginine Splicing Factors