Project description:N6-methyladenosine (m6A) is the most abundant internal messenger (mRNA) modification in mammalian mRNA. This modification is reversible and non-stoichiometric, which potentially adds an additional layer of variety and dynamic control of mRNA metabolism. The m6A-modified mRNA can be selectively recognized by the YTH family “reader” proteins. The preferential binding of m6A-containing mRNA by YTHDF2 is known to reduce the stability of the target transcripts; however, the exact effects of m6A on translation has yet to be elucidated. Here we show that another m6A reader protein, YTHDF1, promotes ribosome loading of its target transcripts. YTHDF1 forms a complex with translation initiation factors to elevate the translation efficiency of its bound mRNA. In a unified mechanism of translation control through m6A, the YTHDF2-mediated decay controls the lifetime of target transcripts; whereas, the YTHDF1-based translation promotion increases the translation efficiency to ensure effective protein production from relatively short-lived transcripts that are marked by m6A. PAR-CLIP and RIP was used to identify YTHDF1 binding sites followed by ribosome profling and RNA seq to assess the consequences of YTHDF1 siRNA knock-down
Project description:The N6-methyladenosine (m6A) is the most abundant internal modification in almost all eukaryotic messenger RNAs, and is dynamically regulated. Therefore, identification of m6A readers is especially important in determining the cellular function of m6A. YTHDF2 has recently been characterized as the first m6A reader that regulates the cytoplasmic stability of methylated RNA. Here we show that YTHDC1 is a nuclear m6A reader and report the crystal structure of the YTH domain of YTHDC1 bound to m6A-containing RNA. We further determined the structure of another YTH domain, YTHDF1, and found that the YTH domain utilizes a conserved aromatic cage to specifically recognize the methyl group of m6A. Our structural characterizations of the YTHDC1-m6A RNA complex also shed light on the molecular basis for the preferential binding of the GG(m6A)C sequence by YTHDC1 and confirm the YTH domain as a specific m6A RNA reader. PAR-CLIP (Photoactivatable-Ribonucleoside-Enhanced Crosslinking and Immunoprecipitation) was applied to human YTHDC1 protein to identify its binding sites.
Project description:The N6-methyladenosine (m6A) mRNA modification and the mitochondrial respiratory chain (MRC) hold paramount importance in the advancement of MASLD. This study thoroughly investigates the relationship and impact of m6A mRNA modification and mitochondrial function in the progression of MASLD. Here we report that the mRNA and protein levels of mitochondrial respiratory chain (MRC) subunits showed inconsistent trends in vivo experiments. Abnormal m6A modification and mitochondrial dysfunction in MASLD were attributed to the upregulation of methyltransferase like 3 (Mettl3) and the downregulation of YTH N6-methyladenosine RNA binding protein 1 (YTHDF1) induced by high-fat foods. Mettl3 promoted the MRC's function. However, knockout of the reader protein YTHDF1, which plays a crucial role in the m6A modification process, counteracted the effect of Mettl3 and suppressed MRC. In MASLD, damage to the MRC may be regulated by the Mettl3-m6A-YTHDF1 complex axis, especially by the role of YTHDF1. Our research has offered a novel perspective on the involvement of m6A mRNA methylation in the pathogenesis of MASLD.
Project description:N6-methyladenosine (m6A) governs the fate of RNAs through m6A readers. Colorectal cancer (CRC) exhibits aberrant m6A modifications and expression of m6A regulators. However, little is known about how m6A readers interpret oncogenic m6A methylome for malignant transformation. m6A reader YTHDF1 was overexpressed by copy number gain/amplification in majority of CRCs. YTHDF1 high expression and CNVs predict increased risk of CRC relapse. Transcriptome profiles of YTHDF1-high tumors exhibit highly metastatic features. YTHDF1 promoted CRC tumor cell and organoid proliferation and enhanced metastasis. Ythdf1 knockout dampened tumor growth in carcinogen-induced CRC model. Through multiomic integration, RhoA activator ARHGEF2 was characterized as the key functional YTHDF1 target based on its m6A and YTHDF1-binding signal, translation efficiency changes, protein correlations with YTHDF1 in clinical samples, and disrupted RhoA features by YTHDF1 knockdown. Moreover, YTHDF1-ARHGEF2 co-regulation was observed in YTHDF1-overexpressing metastatic sites and carcinogen-induced Ythdf1-null CRC tumors. ARHGEF2 overexpression significantly rescued RhoA signaling, tumor cell survival and invasiveness impaired by YTHDF1 knockdown both in vitro and in vivo, further confirming the essential function of ARHGEF2.
Project description:In this study, we show that the m6A modification promotes translation of the ADAR1 transcript, which encodes an A-to-I RNA editing enzyme, in response to interferon stimulation. We reveal that this translation upregulation is mediated by the YTHDF1-dependent pathway; YTHDF1 is a reader protein that can preferentially bind m6A-modified transcripts and promote translation. Knockdown of YTHDF1 reduces the overall levels of interferon-induced A-to-I RNA editing, which consequently activates dsRNA-sensing pathway and increased expression of various interferon-stimulated genes. These RNA-seq experiments investigate the effect of YTHDF1 knockdown on the interferon-treated A172 cell transcriptome.
Project description:The recently described role of RNA methylation in regulating immune cell infiltration into tumors has attracted interest, given its potential impact on immunotherapy response. YTHDF1 is a versatile and powerful m6A reader, but the understanding of its impact on immune evasion is limited. Here, we performed proteomics to reveal the altered proteins between wildtype and YTHDF1 knockout group.
Project description:Modification of RNAs with N6-methadenosine (m6A) has gained attention in recent years as a general mechanism of gene regulation. In the liver, m6A and its associated machinery has been studied as a potential biomarker of disease and cancer, with impacts on metabolism, cell cycle regulation, and pro-cancer state signaling. In vivo studies have begun to explore the effects of m6A in the liver, but differences in outcome of deletion of m6A writers Mettl3 and Mettl14 have not been thoroughly described or explained. Similarly, in vivo studies of the effects of m6A readers such as Ythdf1 and Ythdf2 have not been extended to characterize impacts of dysregulation of these reader proteins in the liver. To understand Mettl14 function, as well as Ythdf1 and Ythdf2, we developed mouse models and found a Mettl14 deletion specific phenotype of progressive liver injury characterized by nuclear heterotypia, with studies highlighting changes in mRNA splicing, processing and export leading to increases in mRNA surveillance and recycling.
Project description:To study the effect of m6A modifications on subcellular mRNA localization we depleted m6A readers Ythdf1, -2 and -3 with shRNAs from mouse primary cortical neurons (mPCN) and sequenced neuritic and somatic compartments in parallel with scrambled shRNA control.
Project description:The recently described role of RNA methylation in regulating immune cell infiltration into tumors has attracted interest, given its potential impact on immunotherapy response. YTHDF1 is a versatile and powerful m6A reader, but the understanding of its impact on immune evasion is limited. Here, we revealed that tumor-intrinsic Ythdf1 drives immune evasion and immune checkpoint inhibitor (ICI) resistance. TMT proteomics analysis was performed to identify the altered protein.