Project description:RNA methylation is involved in the regulation of cell response and cell fate, and is closely related to the development of tumors. METTL14 is considered to be a m6A methyltransferase. Studies have found that METTL14 is associated with the occurrence and development of a variety of tumors, but the mechanism in neuroblastoma is not clear. The expression of METTL14 in high risk patients was significantly higher than that in low risk patients. Interference with METTL14 expression in SK-N-BE(2) cells significantly interfered with cell cycle and inhibited cell proliferation, migration and invasion. In neuroblastoma, METTL14 activates the PI3K/AKT signaling pathway by targeting YWHAH by upregulating m6A levels in mRNA transcripts. In all findings, it was suggested that METTL14 has a cancer-promoting function in neuroblastoma.
Project description:We investigated the mechanism by which the m6A methyltransferase METTL14 functions in neuroblastoma. To explore the downstream target genes of METTL14, we performed RNA-seq analysis and found that the expression profile of the gene was significantly altered in METTL14 knockdown SK-N-BE(2) cells. We found that overexpression of METTL14 in neuroblastoma patients was a detrimental factor.
Project description:N6-methyladenosine (m6A) is the most common modification to mRNA in mammalian cells linked to development and disease. m6A controls CD4+ T cell homeostasis by targeting the IL-7/STAT5/SOCS family pathway and sustains Treg suppressive function. However, the role of m6A modification in non-conventional T cell development and function remains unknown. Here we showed that m6A modification was indispensable for NKT cell homeostasis using mice with T cell-specific deletion of RNA methylation writer METTL14 (T-Mettl14-/-). Loss of METTL14-dependent m6A modification led to the upregulation of p53-mediated apoptosis in double-positive (DP) thymocytes. The decreased lifespan of DP thymocytes reduced the efficiency of distal Va-Ja rearrangement, including the invariant Va14-Ja18 TCR, and therefore led to a profound decrease in the iNKT cell population. The residual iNKT cells in T-Mettl14-/- mice exhibited increased apoptosis and impaired maturation. In addition, loss of METTL14 upregulated Cish expression, which contributed to decreased proliferative response to IL-2 and IL-15 and impaired cytokine production upon TCR stimulation in METTL14-deficient iNKT cells. Furthermore, knocking down METTL14 in mature iNKT cells diminished their cytokine production, correlated with increased Cish expression and decreased TCR signaling. Collectively, our data reveals a critical role for METTL14- dependent-m6A modification in iNKT cell development and function, highlighting the need to take this effect into consideration for targeting m6A pathway in therapeutic settings.
Project description:Accumulation of unfolded or misfolded proteins in the endoplasmic reticulum (ER) lumen triggers unfolded protein response (UPR) for stress adaptation, the failure of which induces cell apoptosis and tissue/organ damage. The molecular switches underlying how the UPR selects for stress adaptation over apoptosis remain unknown. Here we discovered that accumulation of unfolded/misfolded proteins selectively induces N6-adenosine-methyltransferase-14 (METTL14) expression. METTL14 promotes CHOP mRNA decay through its 3’UTR N6-adenosine methylation (m6A) to inhibit its downstream pro-apoptotic target genes expression. UPR induces METTL14 expression through competing the HRD1-ERAD machinery to block METTL14 ubiquitination and degradation. Therefore, mice with liver-specific METTL14 deletion are highly susceptible to both acute pharmacological and alpha-1 antitrypsin (AAT) deficiency-induced ER proteotoxic stress and liver injury. Further hepatic CHOP deletion protects METTL14 knockout mice from ER stress-induced liver damage. Our study reveals a crosstalk between ER stress and mRNA m6A pathways, the ERm6A pathway, for ER stress adaptation to proteotoxicity.
Project description:Methyltransferase-like 3 (METTL3) and 14 (METTL14) are core subunits of the methyltransferase complex (MTC) that catalyzes mRNA N6-methyladenosine (m6A) modification. Despite the expanding list of m6A-dependent function of the MTC, m6A independent function of the METTL3 and METTL14 complex remains poorly understood. Here we show that genome-wide redistribution of METTL3 and METTL14 drives senescence-associated secretory phenotype (SASP) in a m6A-independent manner. METTL3 and METTL14 are necessary for SASP. However, SASP is not regulated by m6A mRNA modification. METTL14 is redistributed to the enhancers, while METTL3 is localized to the pre-existing NF-B sites within the promoters of the SASP genes during senescence. METTL3 interacts with NF-B and they are mutually dependent on their associations with the promoters of SASP genes. METTL14 but not METTL3 is necessary for function of SASP gene enhancers. METTL3 and METTL14 are required for both the tumor-promoting and immune surveillance functions of senescent cells mediated by SASP in vivo in mouse models. In summary, our results report a m6A independent function of the METTL3 and METTL14 complex in promoting SASP through regulating transcription by genome-wide redistribution of METTL14 to enhancers and METTL3 to promoters of SASP genes during senescence.
Project description:To elucidate the role of METTL14-mediated m6A modification in epidermal development, we conditionally knocked out the m6A methyltransferase METTL14 in mouse epidermal keratinocytes. We then performed MeRIP-seq analysis of epidermal keratinosis from P0 control mice (K14Cre,Mettl14F/+).
Project description:Methyltransferase-like 3 (METTL3) and 14 (METTL14) are core subunits of the methyltransferase complex (MTC) that catalyzes mRNA N6-methyladenosine (m6A) modification. Despite the expanding list of m6A-dependent function of the MTC, m6A independent function of the METTL3 and METTL14 complex remains poorly understood. Here we show that genome-wide redistribution of METTL3 and METTL14 drives senescence-associated secretory phenotype (SASP) in a m6A-independent manner. METTL3 and METTL14 are necessary for SASP. However, SASP is not regulated by m6A mRNA modification. METTL14 is redistributed to the enhancers, while METTL3 is localized to the pre-existing NF-B sites within the promoters of the SASP genes during senescence. METTL3 interacts with NF-B and they are mutually dependent on their associations with the promoters of SASP genes. METTL14 but not METTL3 is necessary for function of SASP gene enhancers. METTL3 and METTL14 are required for both the tumor-promoting and immune surveillance functions of senescent cells mediated by SASP in vivo in mouse models. In summary, our results report a m6A independent function of the METTL3 and METTL14 complex in promoting SASP through regulating transcription by genome-wide redistribution of METTL14 to enhancers and METTL3 to promoters of SASP genes during senescence.
Project description:To elucidate the role of METTL14-mediated m6A modification in epidermal development, we conditionally knocked out the m6A methyltransferase METTL14 in mouse epidermal keratinocytes. We then performed RNA-seq analysis of epidermal keratinosis from P0 control mice (K14Cre,Mettl14F/+) and cKO mice (K14CreMettl14F/F).
Project description:To elucidate the role of METTL14-mediated m6A modification in epidermal development, we conditionally knocked out the m6A methyltransferase METTL14 in mouse epidermal keratinocytes. We then performed ribosome-profiling analysis of epidermal keratinosis from P0 control mice (K14Cre,Mettl14F/+) and cKO mice (K14CreMettl14F/F).
Project description:METTL3 and METTL14 are two components that form the core heterodimer of the main RNA m6A methyltransferase complex (MTC, also known as m6A writer) that installs m6A. Surprisingly, depletion of METTL3 or METTL14 displayed distinct effects on mouse embryonic stem cell (mESC) self-renewal. While comparable global hypo-methylation in RNA m6A was observed in Mettl3 or Mettl14 knockout mESCs, respectively. Mettl14 knockout led to a globally decreased nascent RNA synthesis, whereas Mettl3 depletion resulted in transcription upregulation, suggesting that METTL14 might possess an m6A-indenepent role in gene regulation. We found that METTL14 colocalizes with the repressive H3K27me3 modification and PRC2 complex. Mechanically, METTL14, but not METTL3, recognizes H3K27me3 and recruits KDM6B to induce H3K27me3 demethylation independent of METTL3. Depletion of METTL14 thus led to a global increase in H3K27me3 level along with a global gene suppression . The regulation of H3K27me3 by METTL14 is essential to the transition of mESCs from self-renewal to differentiation. This work reveals a regulation mechanism on heterochromatin by METTL14 in a manner distinct from METTL3 and independently of m6A, and critically impacts transcriptional regulation, stemness maintenance and differentiation of mESCs.