CREB-binding protein (CBP)/p300 and RNA polymerase II colocalize in transcriptionally active domains in the nucleus.
The spatial organization of transcription- associated proteins is an important control mechanism of eukaryotic gene expression. Here we analyzed the nuclear distribution of the transcriptional coactivators CREB-binding protein (CBP)/p300 in situ by confocal laser scanning microscopy, and in vivo complex formation by coimmunoprecipitation. A subpopulation of CBP and p300 is targeted to active sites of transcription and partially colocalizes with hyper- and hypophosphorylated RNA polymerase II (pol II) in discrete regions of variable size throughout the nucleus. However, the coactivators were found in tight association with hypophosphorylated, but not hyperphosphorylated pol II. Transcriptional inhibition induced a relocation of CBP/p300 and pol II into speckles. Moreover, double and triple immunofluorescence analyses revealed the presence of CBP, p300, and pol II in a subset of promyelocytic leukemia (PML) bodies. Our results provide evidence for a dynamic spacial link between coactivators of transcription and the basal transcription machinery in discrete nuclear domains dependent upon the transcriptional activity of the cell. The identification of pol II in CBP/PML-containing nuclear bodies supports the idea that transcription takes place at PML bodies.
von Mikecz
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Junior Research Group of Molecular Cell Biology, Medizinisches Institut für Umwelthygiene, Heinrich-Heine-Universät Düsseldorf, 40225 Düsseldorf, Germany.
Zhang
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Montminy
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Tan
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EM
Hemmerich
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D000123:Acetyltransferases / Q000378:metabolism*; D050882:CREB-Binding Protein; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D051548:Histone Acetyltransferases; D006801:Humans; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D009687:Nuclear Proteins / Q000378:metabolism*; D011233:Precipitin Tests; D012319:RNA Polymerase II / Q000378:metabolism*; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors; D014158:Transcription, Genetic / Q000235:genetics*; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor
D000123:Acetyltransferases; D050882:CREB-Binding Protein; D018797:Cell Cycle Proteins; D051548:Histone Acetyltransferases; D009687:Nuclear Proteins; D012319:RNA Polymerase II; D015534:Trans-Activators; D014157:Transcription Factors; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C494363:CREBBP protein, human