Ultrastructural distribution of the death-domain-containing MyD88 protein in HeLa cells.
MyD88, a protein implicated in interleukin-1 signaling, was localized in HeLa cells transiently transfected with an epitope-tagged (flag) version of MyD88. Overexpression of MyD88 can induce apoptosis. We have analyzed the fine structural intracellular distribution of MyD88 using immunoelectron microscopy. MyD88 is localized to the nucleus and to the cytoplasm as revealed by immunofluorescence visualization. Ultrastructural immunocytochemistry shows that, in the cytoplasm, this protein is associated with fibrillar aggregates containing beta-actin. In the nucleus, MyD88 was found in fibrillar domains present only in cells not yet displaying morphological signs of apoptosis. These domains are not derived from nucleoli and do not constitute an accumulation site of splicing factors. We suggest that such structures could be involved in the formation of the apoptotic bodies and/or in the modification of the nuclear structure and of nucleocytoplasmic trafficking during apoptosis.
Center for Electron Microscopy, University of Lausanne, 27 Bugnon, Lausanne, CH-1005, Switzerland.
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Jaunin
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Burns
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Tschopp
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Martin
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Fakan
D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D017209:Apoptosis / Q000235:genetics*; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression; D006367:HeLa Cells / Q000378:metabolism* / Q000648:ultrastructure; D006801:Humans; D007150:Immunohistochemistry; D016253:Microscopy, Immunoelectron; D053594:Myeloid Differentiation Factor 88; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011971:Receptors, Immunologic; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; D000943:Antigens, Differentiation; D003598:Cytoskeletal Proteins; C507779:MYD88 protein, human; D053594:Myeloid Differentiation Factor 88; D011506:Proteins; D011971:Receptors, Immunologic