Abstract
RNA polymerase I (Pol I) transcription is essential for the cell cycle, growth and protein synthesis in eukaryotes. In the present study, we found that phosphatidylinositol 4,5-bisphosphate (PIP2) is a part of the protein complex on the active ribosomal promoter during transcription. PIP2 makes a complex with Pol I and the Pol I transcription factor UBF in the nucleolus. PIP2 depletion reduces Pol I transcription, which can be rescued by the addition of exogenous PIP2. In addition, PIP2 also binds directly to the pre-rRNA processing factor fibrillarin (Fib), and co-localizes with nascent transcripts in the nucleolus. PIP2 binding to UBF and Fib modulates their binding to DNA and RNA, respectively. In conclusion, PIP2 interacts with a subset of Pol I transcription machinery, and promotes Pol I transcription.
Keywords:
Fibrillarin; Nucleolus; PIP2; Transcription; UBF.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Cell Line, Tumor
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Cell Nucleolus / genetics
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Cell Nucleolus / metabolism
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Chromosomal Proteins, Non-Histone / genetics
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Chromosomal Proteins, Non-Histone / metabolism
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DNA-Binding Proteins / genetics
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DNA-Binding Proteins / metabolism
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HeLa Cells
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Humans
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Phosphatidylinositol 4,5-Diphosphate / genetics*
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Phosphatidylinositol 4,5-Diphosphate / metabolism*
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Pol1 Transcription Initiation Complex Proteins / genetics
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Pol1 Transcription Initiation Complex Proteins / metabolism
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Promoter Regions, Genetic / genetics
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RNA Polymerase I / genetics*
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RNA Polymerase I / metabolism*
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RNA Precursors / genetics
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RNA Precursors / metabolism
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Transcription, Genetic / genetics*
Substances
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Chromosomal Proteins, Non-Histone
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DNA-Binding Proteins
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Phosphatidylinositol 4,5-Diphosphate
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Pol1 Transcription Initiation Complex Proteins
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RNA Precursors
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fibrillarin
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transcription factor UBF
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RNA Polymerase I