Project description:Reversible RNA modification of N6-methyladenosine (m6A) plays a critical role in post-transcriptional gene regulation1-13. Although the fat mass and obesity-associated protein (FTO) has been previously shown to function as an m6A demethylase in nuclear RNA1,14, its exact function in disease pathogenesis remains a mystery. Here, we demonstrate that FTO suppresses the activation of Rho GTPase signaling via both its demethylation activity and specific interaction with Rho effector, Rhotekin (RTKN)15. The knockdown of FTO activates RhoA and RhoC, induces stress fibres, and accelerates cell migration. Endogenous RTKN is highly expressed in certain cancer and cancer-derived cell lines16,17 with overexpression of RTKN leading to moderate activation of Rho18. We further found that overexpression of RTKN blocks nuclear import of FTO and traps FTO in the cytoplasm to mediate m6A demethylation of cytosolic mRNA, thereby changing gene expression by preventing m6A-dependent mRNA decay and translation. Our results illustrate how FTO represses Rho activation through m6A demethylation and direct interaction with RTKN, and shed new light on FTO-dependent post-transcriptional gene regulation in RTKN overexpressed cancers, which may provide a new direction for developing anti-cancer therapies.
Project description:FTO, an N6-methyladenosine (m6A) demethylase, can promote cervical cancer cell proliferation and migration. RNA-sequencing of SiHa cells with FTO knockdown was conducted to dissect the differentially expressed genes and the potential mechanism of FTO in cervical cancer.
Project description:We identified the major RNA binding protein-SFPQ as a direct interaction partner of FTO. Our study showed that FTO and SFPQ were located in close proximity throughout the transcriptome and overexpression of SFPQ led to the demethylation of adjacent N6-methyladenosine on RNA
Project description:N6-methyladenosine (m6A) RNA methylation is the most abundant internal chemical modifications in eukaryotic messenger RNA (mRNA) as well as long non-coding RNA (lncRNA). Recently, m6A RNA methylation research was revived by the discovery of the fat mass- and obesity-associated protein (FTO) as the first RNA demethylase, implicating that m6A RNA methylation is a reversible and dynamic modification and may have critical biological functions. Emerging evidence has shown that m6A modifications in mRNAs and lncRNAs play crucial roles in regulating RNA fate and function in biological processes in the past several years. As the first identified RNA demethylase that regulates the demethylation of target mRNAs, FTO has been reported to play an oncogenic role in leukemia and glioblastoma stem cells. To identify the target genes of FTO in melanoma cells, we used microarray analysis to determine the potential demethylation and gene targets across the whole transcriptome for FTO, and identified more than 100 genes.
Project description:N6-methyladenosine (m6A) RNA methylation is the most abundant internal chemical modifications in eukaryotic messenger RNA (mRNA) as well as long non-coding RNA (lncRNA). Recently, m6A RNA methylation research was revived by the discovery of the fat mass- and obesity-associated protein (FTO) as the first RNA demethylase, implicating that m6A RNA methylation is a reversible and dynamic modification and may have critical biological functions. Emerging evidence has shown that m6A modifications in mRNAs and lncRNAs play crucial roles in regulating RNA fate and function in biological processes in the past several years. As the first identified RNA demethylase that regulates the demethylation of target mRNAs, FTO has been reported to play an oncogenic role in leukemia and glioblastoma stem cells. To identify the target genes of FTO in melanoma cells, we used m6A IP seq coupled with RNA seq to determine the potential demethylation and gene targets across the whole transcriptome for FTO, and identified more than 1,000 genes.
Project description:N6-methyladenosine (m6A) modification of messenger RNAs (mRNAs) is a pivotal mechanism controlling mRNA fate in cells. RNA m6A modification is regulated by the functional balance between methyltransferases and demethylases. Here we demonstrated that FTO-IT1 enhancer RNA (eRNA), a long non-coding RNA (lncRNA) transcribed from the last intron of FTO gene is significantly upregulated in CRPC and aggressive tumors compared to primary tumors. FTO-IT1 knockout by CRISPR/Cas9 almost completely blocks growth and G1-S cell cycle transition of both androgen-sensitive and castration-resistant prostate cancer cells. Meanwhile, the mRNA m6A was dramatically increased in FTO-IT knockout PCa cells and we identified FTO-IT1 as a binding partner of FTO. From m6A-seq, we unexpectedly found hypermethylated m6A associated with upregulated levels of the mRNAs for p53 signaling pathway genes in 22Rv1 prostate cancer cells. Mechanistic study showed that FTO-IT1 recruits FTO to the P53 target mRNA to promote their m6A demethylation, which leads to their degradation.
Project description:The FTO gene locus has been linked to cancer and obesity through encoded N6-methyladenosine (m6A) demethylase FTO or inherited genomic variants (e.g. intronic single-nucleotide polymorphisms). Here we demonstrate that FTO-IT1, a long noncoding RNA (lncRNA) transcribed from a FTO gene intron, is upregulated during prostate cancer (PCa) progression and positively correlated with poor survival of patients with tumors only expressing wild-type p53. We show that RBM15, a mRNA/substrate binding subunit of the m6A methyltransferase complex binds and increases mRNA m6A methylation and stability of p53 transcriptional target genes; however, FTO-IT1 overexpression abolishes these effects by blocking RBM15 binding of p53 target gene mRNAs. Therapeutic targeting of FTO-IT1 restores mRNA m6A level and p53 signaling and inhibits PCa tumor growth in mice. Our study identifies FTO-IT1 lncRNA as a bono fide inhibitor of m6A methylation and p53 tumor suppression and nominates FTO-IT1 as a potential biomarker and therapeutic target of cancer.
Project description:N6-methyladenosine (m6A) is the most abundant internal modification in the messenger RNA (mRNA) of all higher eukaryotes. This modification has been shown to be reversible in mammals; it is installed by a methyltransferase heterodimer complex of METTL3 and METTL14 bound with WTAP, and reversed by iron(II)- and α-ketoglutarate-dependent demethylases FTO and ALKBH5. This modification exhibits significant functional roles in various biological processes. The m6A modification as a RNA mark is recognized by reader proteins, such as YTH domain family proteins and HNRNPA2B1; m6A can also act as a structure switch to affect RNA-protein interactions for biological regulation. In Arabidopsis thaliana, the methyltransferase subunit MTA (the plant orthologue of human METTL3, encoded by At4g10760) was well characterized and FIP37 (the plant orthologue of human WTAP) was first identified as the interacting partner of MTA. Here we report the discovery and characterization of reversible m6A methylation mediated by AtALKBH10B (encoded by At4g02940) in A. thaliana, and noticeable roles of this RNA demethylase in affecting plant development and floral transition. Our findings reveal potential broad functions of reversible mRNA methylation in plants. m6A peaks were identified from wild type Columbia-0 and atalkbh10b-1 mutant in two biological replicates
Project description:FTO, the first RNA demethylase discovered, mediates the demethylation of N6-methyladenosine (m6A), installed internally on messenger RNA, and N6,2′-O-dimethyladenosine (m6Am), occurring at the +1 position from the 5’ cap. Despite extensive recent research on FTO, its physiological impact on cellular processes has yet to be fully elucidated. Here, we demonstrate that the cellular distribution of FTO is distinct among different cell lines, which critically affects the access of FTO to different RNA substrates. FTO binds multiple RNA substrates, including mRNA, U6 RNA, and tRNA. It mainly targets internal m6A when located in the cell nucleus and preferentially demethylates m6Am when residing in the cytoplasm. The expression levels of transcripts containing internal m6A are associated with the alteration of the FTO more so than transcripts containing m6Am. We also discover that N1-methyladenosine (m1A) in tRNA is a main substrate of FTO, with the FTO-catalyzed demethylation of target tRNAs repressing protein synthesis. Collectively, FTO-mediated RNA demethylation affects both mRNA level and translation through distinct pathways.
Project description:N6-methyladenosine (m6A) is the most abundant internal modification in mammalian messenger RNA (mRNA). It is installed by writer proteins and can be reversed by erasers. FTO was the first RNA demethylase shown to catalyze oxidative demethylation of m6A in RNA. Despite extensive studies, the main physiological substrates of FTO and the related functional pathways remain elusive in many systems, in particular during early mammalian development. Here, we show that FTO mediates the m6A demethylation of chromosome-associated repeat RNAs in mouse embryonic stem cells (mESCs), especially the long-interspersed element-1 family (LINE1) RNA, thereby affecting their abundances to regulate chromatin state.