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Identification of nucleolin and nucleophosmin as genotoxic stress-responsive RNA-binding proteins
Chonglin Yang1, Dony A Maiguel, France Carrier
1University of Maryland, Baltimore, School of Medicine, Biochemistry and Molecular Biology Department, 108 North Greene Street, Baltimore, MD 21201-1503, USA.
Abstract:
Genotoxic stress (DNA damage) can elicit multiple responses in mammalian cells, including the activation of numerous cascades of signal transduction that result in the activation of cellular genes involved in growth control, DNA repair and apoptosis. In an earlier report, we have shown that DNA-damaging agents can also induce the RNA-binding activity of several specific proteins that favor a double stem-loop RNA structure. Here we report the purification and identification of nucleophosmin (NPM) and nucleolin as two genotoxic stress-responsive RNA-binding proteins. UV radiation induces the protein expression levels and RNA-binding activity of NPM while nucleolin RNA-binding activity increases after UV or ionizing radiation exposure. Moreover, we have identified 40 mRNA ligands that are potentially regulated by nucleolin, several of which are stress-responsive transcripts. In addition, our data indicate that activation of nucleolin RNA-binding activity by genotoxic stress is mediated by stress-activated protein kinase p38. Our findings suggest that activation of the RNA-binding properties of nucleolin and NPM is part of the cellular response to genotoxic stress.
Insights
Genotoxic stress activates RNA-binding proteins like nucleophosmin (NPM) and nucleolin in mammalian cells. This study identifies NPM and nucleolin as key players in the cellular response to DNA damage.
Area of Science:
- Molecular Biology
- Cell Biology
- Genetics
Background:
- Genotoxic stress, or DNA damage, triggers complex cellular responses including signal transduction, gene activation, DNA repair, and apoptosis.
- Previous research indicated that DNA-damaging agents can enhance the RNA-binding activity of specific proteins interacting with double stem-loop RNA structures.
Purpose of the Study:
- To identify and characterize RNA-binding proteins that respond to genotoxic stress.
- To elucidate the role of nucleophosmin (NPM) and nucleolin in cellular responses to DNA damage.
Main Methods:
- Purification and identification of stress-responsive RNA-binding proteins.
- Analysis of protein expression levels and RNA-binding activity following UV and ionizing radiation exposure.
- Identification of mRNA targets regulated by nucleolin using RNA-binding assays.
Main Results:
- Nucleophosmin (NPM) and nucleolin were identified as genotoxic stress-responsive RNA-binding proteins.
- UV radiation increased NPM expression and RNA-binding activity; UV and ionizing radiation elevated nucleolin RNA-binding activity.
- Nucleolin was found to potentially regulate 40 mRNA targets, including stress-responsive transcripts, with its activity mediated by p38 kinase.
Conclusions:
- Nucleophosmin (NPM) and nucleolin are integral components of the mammalian cellular response to genotoxic stress.
- The activation of RNA-binding capabilities by these proteins is a significant aspect of DNA damage response pathways.