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[The immunolocalization of the ribosomal gene transcription initiation factor UBF in the interphase and mitosis]

O V Zatsepina, A N Prusov, M V Semenov

    Tsitologiia
    |January 1, 1995
    PubMed

    Insights

    Rheumatoid arthritis serum P419 identifies UBF (RNA polymerase I transcription factor) by labeling nucleoli. UBF localization changes dramatically when rRNA synthesis is blocked, impacting its distribution in cells.

    Area of Science:

    • Molecular Biology
    • Cell Biology
    • Immunology

    Context:

    • Nucleoli are crucial cellular compartments involved in ribosome biogenesis.
    • Rheumatoid arthritis serum P419 exhibits high specificity for nucleolar components.
    • Understanding the regulation of rRNA synthesis is key to cell function.

    Purpose:

    • To identify the specific protein recognized by rheumatoid arthritis serum P419.
    • To investigate the localization and dynamics of this protein within mammalian cells.
    • To determine the protein's behavior under conditions of altered rRNA synthesis.

    Summary:

    • Serum P419 from a rheumatoid arthritis patient specifically immunolabels nucleoli.
    • Western blot analysis identified the target as UBF (Upstream Binding Factor), a 97/94 kDa polypeptide crucial for RNA polymerase I transcription.
    • UBF remains associated with nucleoli and NORs, but its intranucleolar localization is altered upon rRNA synthesis inhibition, with altered distribution in pycnotic cells and during mitosis.

    Impact:

    • Identifies UBF as a specific target of serum P419, providing a novel tool for UBF research.
    • Reveals dynamic changes in UBF localization in response to rRNA synthesis modulation.
    • Offers insights into the regulation of transcription factor organization within the nucleolus and during cell division.

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