Abstract
The HIV-1 ribonucleoprotein (RNP) contains the major structural protein, pr55(Gag), viral genomic RNA, as well as the host protein, Staufen1. In this report, we show that the nonsense-mediated decay (NMD) factor UPF1 is also a component of the HIV-1 RNP. We investigated the role of UPF1 in HIV-1-expressing cells. Depletion of UPF1 by siRNA resulted in a dramatic reduction in steady-state HIV-1 RNA and pr55(Gag). Pr55(Gag) synthesis, but not the cognate genomic RNA, was efficiently rescued by expression of an siRNA-insensitive UPF1, demonstrating that UPF1 positively influences HIV-1 RNA translatability. Conversely, overexpression of UPF1 led to a dramatic up-regulation of HIV-1 expression at the RNA and protein synthesis levels. The effects of UPF1 on HIV-1 RNA stability were observed in the nucleus and cytoplasm and required ongoing translation. We also demonstrate that the effects exerted by UPF1 on HIV-1 expression were dependent on its ATPase activity, but were separable from its role in NMD and did not require interaction with UPF2.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Base Sequence
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Cell Line
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Cell Nucleus / metabolism
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Cytoskeletal Proteins / genetics
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Cytoskeletal Proteins / metabolism
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Genes, gag
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HIV-1 / genetics*
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HIV-1 / metabolism*
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HeLa Cells
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Humans
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Mutation
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Protein Biosynthesis
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Protein Precursors / genetics
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Protein Precursors / metabolism
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RNA Helicases
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RNA Stability
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RNA, Small Interfering / genetics
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RNA, Viral / genetics*
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RNA, Viral / metabolism*
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RNA-Binding Proteins / genetics
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RNA-Binding Proteins / metabolism
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Recombinant Proteins / genetics
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Recombinant Proteins / metabolism
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Ribonucleoproteins / genetics
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Ribonucleoproteins / metabolism
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Trans-Activators / antagonists & inhibitors
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Trans-Activators / genetics
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Trans-Activators / metabolism*
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Transfection
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gag Gene Products, Human Immunodeficiency Virus / genetics
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gag Gene Products, Human Immunodeficiency Virus / metabolism
Substances
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Cytoskeletal Proteins
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Protein Precursors
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RNA, Small Interfering
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RNA, Viral
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RNA-Binding Proteins
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Recombinant Proteins
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Ribonucleoproteins
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STAU1 protein, human
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Trans-Activators
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gag Gene Products, Human Immunodeficiency Virus
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p55 gag precursor protein, Human immunodeficiency virus 1
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RNA Helicases
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UPF1 protein, human