Effect of depletion of FXR1 on gene expression in head and neck squamous cell carcinoma (HNSCC) cells
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ABSTRACT: FXR1 is an essential RNA-binding protein. This chromosome 3q26-28 gene is overexpressed in many epithelial tumors. FXR1 controls the turnover and translation of multiple mRNAs and is involved in cellular transformation. We identified critical residues in the protein that are post-translationally modified. These regulate the stability of FXR1 protein, its RNA-binding function, cell growth, and proliferation. Here we show that PRMT5-mediated arginine methylation of FXR1 increases the protein's binding to G-quadruplex RNAs in vivo and controls their expression in cancer cells. Independent point mutations of specific arginine residues in the nuclear export signal (R386, R388) and arginine-glycine rich (R453, R455, R459) domains of FXR1 abrogate the RNA-binding in vitro. Genetic and small molecule inhibition of PRMT5 minimizes methylation and levels of FXR1 and suppresses oral tumor growth and proliferation. RNA-seq analyses of FXR1 KD cells show an increase in the expression of PLK2, TCN2, and TRAF4 along with FXR1’s well-known target CDKN1A. Like CDKN1A, these targets possess strong G4 sequences. FXR1 and G4-RNA interactions provide new insights into the molecular mechanism of FXR1 and its interaction with target mRNAs. Furthermore, an increased expression of FXR1 and PRMT5 is colocalized in cancer tissues, leading to a poor patient prognosis. Thus, our data demonstrate that PRMT5-mediated arginine methylation of FXR1 arginine residues in the NES and RGG domains plays a critical role in binding and controlling G4-RNAs, which encode tumor suppressors and promote cancer cell growth and proliferation.
ORGANISM(S): Homo sapiens
PROVIDER: GSE212760 | GEO | 2023/09/30
REPOSITORIES: GEO
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