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) is the most abundant internal modification on mammalian messenger RNA (mRNA). It is installed by a writer complex and can be reversed by erasers such as the fat mass and obesity-associated protein (FTO). Despite extensive research, the primary physiological substrates of FTO in mammalian tissues and development remain elusive. Here, we show that FTO mediates m6A demethylation of long-interspersed element-1 (LINE1) RNA in mouse embryonic stem cells (mESCs), regulating LINE1 RNA abundance and the local chromatin state, which in turn modulates transcription of LINE1-containing genes. FTO-mediated LINE1 RNA m6A demethylation also plays regulatory roles in shaping chromatin state and gene expression during mouse oocyte and embryonic development. Our results suggest broad effects of LINE1 RNA m6A demethylation by FTO in mammals.
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.
Project description:The fat mass and obesity-associated (FTO) protein is a well-characterized demethylase that removes N6-methyladenosine (m6A) from animal mRNAs. However, it is unclear yet how the demethylation operates in living cells. In this study, we applied genome-wide approaches to study how FTO finds its demethylation targets in human cells. We overexpressed FTO in human HeLa cells, demonstrating that FTO effectively removes m6A from the RRACH motif enriched in the 3’UTR regions and leaves m6A at other motifs unaffected. RRACH elements are clearly enriched at FTO binding sites; however, m6A has a lower tendency to be removed from the FTO-bound RRACH. Taken together with the experimental validaton results, we propose a model in which FTO effectivly recognizes m6A-containing RRACH motifs in RNAs, leading to a faster demethylation and dissociation kinetic than the association, and consequently undectable FTO-mRNA association. However, when FTO binds to the non-m6A RRACH motif, the binding has a lower dissociation kinetics, yielding the detectable FTO binding signals which would enable FTO to have roles in regulating other mRNA processing events.
Project description:Here we use MeRIP-Seq to analyze global adenosine methylation (m6A) in mRNAs in the midbrain and striatum of Fto-deficient mice. We find that Fto deficiency leads to increased methylation within a subset of mRNAs important for neuronal signaling, including many within the dopaminergic signaling pathway. Collectively, our results show that Fto regulates demethylation of specific mRNAs in vivo, and this activity relates to control of dopaminergic transmission. Profiling of m6A in midbrain and striatum from FTO knockout mice
Project description:Single nucleotide polymorphisms in the FTO gene encoding a m6A demthylase are associated with obesity and cancer development. However, the functional role of FTO in the developemnt of progression of hepatocellular carcinoma (HCC) as a proteotypic obesity-associated cancer remains unclear. Here, we have generated mice with hepatic FTO deficiency (FTOL-KO) and subjected them to DEN induced HCC-development. FTOL-KO mice exhibit increased HCC burden. While control mice exhibit a dynamic regulation of FTO upon induction of liver damage, this response is abrogated in mice lacking FTO. Proteomic analyses revealed that liver damage-induced increases in FTO expression promotes m6A-demethylation of CUL4A reducing its protein expression. Functionally, knockdown of CUL4A restores the increased hepatocyte proliferation observed upon loss of FTO. Collectively, our study reveals a protective role for FTO-dependent dynamic m6A mRNA demethylation of CUL4A in the initiation of HCC development.
Project description:Background: Despite its functional importance in various fundamental bioprocesses, the studies of N6-methyladenosine (m6A) in the heart are lacking. Methods: We performed methylated (m6A) RNA immunoprecipitation sequencing (MeRIP-seq) to map transcriptome-wide m6A in healthy and failing hearts. Results: Improving expression of FTO in failing mouse hearts attenuated the ischemia-induced increase in m6A and decrease in cardiac contractile function. This is carried out by the demethylation activity of FTO, which selectively demethylates cardiac contractile transcripts Conclusion: Collectively, our study demonstrates the functional importance of FTO-dependent cardiac m6A methylome in cardiac contraction during heart failure and provides a novel mechanistic insight into the therapeutic mechanisms of FTO.
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:The discovery of activating mutations in receptor tyrosine kinases (RTKs) leads to clinical testing of RTK inhibitors (TKIs). However, the rapid acquisition of resistance limits TKI effectiveness. Here we establish TKI-resistant cells that propagate in the absence of RTK signaling. Relative to sensitive cells, TKI-resistant cells display decreased N6-methyladenosine (m6A), a ubiquitous and reversible modification on RNA, but upregulated fat mass and obesity-associated gene (FTO), an m6A demethylase. Notably, the naïve leukemia cell populations are heterogeneous with respect to FTO levels. Cells with higher intrinsic and transient FTO expression demonstrate reduction of m6A methylation and TKI sensitivity with higher tumorigenic. Genetic or pharmacological dysfunction of FTO increases m6A abundance sensitizing resistant cells to TKIs. Mechanistically, FTO-mediated m6A demethylation promotes mRNA stability and protein translation rate, upregulating oncogenes that are indispensable for survival and proliferation. Our findings therefore establish a role of FTO-dependent m6A demethylation for TKI-resistance, offering a therapeutic window for incorporating m6A modulators in counteracting acquired TKI resistance.