Project description:N6-methyladenosine (m6A) is the most prevalent post-transcriptional modification on RNA. NK cells are the predominant innate lymphoid cells that mediate anti-viral and anti-tumor immunity. However, whether and how m6A modifications affect NK cell immunity remains unknown. Here, we discover that YTHDF2, a well-known m6A reader, is upregulated in NK cells upon activation by cytokines, tumors, and cytomegalovirus infection. Ythdf2 deficiency in NK cells impairs NK cell anti-tumor and anti-viral activity in vivo. YTHDF2 maintains NK cell homeostasis and terminal maturation, correlating with modulating NK cell trafficking and regulating Eomes, respectively. YTHDF2 promotes NK cell effector function and is required for IL-15-mediated NK cell survival and proliferation by forming a STAT5-YTHDF2 positive feedback loop. Transcriptome-wide screening identifies Tardbp to be involved in cell proliferation or survival as a YTHDF2-binding target in NK cells. Collectively, we elucidate the biological roles of m6A modifications in NK cells and highlight a new direction to harness NK cell anti-tumor immunity.
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 presence of tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) affects cancer progression and immunotherapy response. The RNA m6A methylation, an epigenetic modification, has recently been found to play a pivotal role in shaping the TME. However, the role and underlying mechanisms by which RNA m6A methylation regulates TAMs function and anti-tumor immunity remain elusive. Here we show that depletion of YTHDF2, a well-known m6A reader, in TAMs suppresses tumor growth and metastasis. Myeloid YTHDF2 deficiency reprograms TAMs to anti-tumorigenic type and increases their cross-presentation ability, thereby enhancing CD8+T cell-mediated anti-tumor immunity. Transcriptome-wide screening identifies YTHDF2 deficiency facilitates anti-tumorigenic TAMs reprogramming through targeting IFN-γSTAT1 signaling. Selectively targeting YTHDF2 in TAMs using toll-like receptor 9 agonist - conjugated small interfering RNA against YTHDF2 effectively promotes anti-tumor immunity, restrains tumor growth, and enhances the efficacy of anti-PD-L1 therapy. Together, our findings suggest that YTHDF2 in TAMs might be a promising therapeutic target for cancer immunotherapy.
Project description:The presence of tumor-associated macrophages (TAMs) in the tumor microenvironment (TME) affects cancer progression and immunotherapy response. The RNA m6A methylation, an epigenetic modification, has recently been found to play a pivotal role in shaping the TME. However, the role and underlying mechanisms by which RNA m6A methylation regulates TAMs function and anti-tumor immunity remain elusive. Here we show that depletion of YTHDF2, a well-known m6A reader, in TAMs suppresses tumor growth and metastasis. Myeloid YTHDF2 deficiency reprograms TAMs to anti-tumorigenic type and increases their cross-presentation ability, thereby enhancing CD8+T cell-mediated anti-tumor immunity. Transcriptome-wide screening identifies YTHDF2 deficiency facilitates anti-tumorigenic TAMs reprogramming through targeting IFN-γ-STAT1 signaling. Selectively targeting YTHDF2 in TAMs using toll-like receptor 9 agonist - conjugated small interfering RNA against YTHDF2 effectively promotes anti-tumor immunity, restrains tumor growth, and enhances the efficacy of anti-PD-L1 therapy. Together, our findings suggest that YTHDF2 in TAMs might be a promising therapeutic target for cancer immunotherapy.
Project description:N6-methyladenosine (m6A) in messenger RNA (mRNA) regulates immune cells in homeostasis and in response to infection and inflammation. The function of the m6A reader YTHDF2 in the tumor microenvironment (TME) in these contexts has not been explored. We discovered that the loss of YTHDF2 in regulatory T (Treg) cells reduces tumor growth in mice. Deletion of Ythdf2 in Tregs does not affect peripheral immune homeostasis but leads to increased apoptosis and impaired suppressive function of Treg cells in the TME. Elevated tumor necrosis factor (TNF) signaling in the TME promotes YTHDF2 expression, which in turn regulates NF-κB signaling by accelerating the degradation of m6 A-modified transcripts that encode NF-κB-negative regulators. This TME-specific regulation of Treg by YTHDF2 points to YTHDF2 as a potential target for anti-cancer immunotherapy, where intratumoral Treg cells can be targeted to enhance anti-tumor immune response while avoiding Treg cells in the periphery to minimize undesired inflammations.
Project description:Dynamic N6-methyladenosine (m6A) modification was previously identified as a ubiquitous post-transcriptional regulation that affected mRNA homeostasis. However, the m6A-related epitranscriptomic alterations and functions remain elusive in human diseases such as cancer. Here we show that hypoxia regulates the ‘reader’ protein YTH domain family 2 (YTHDF2), to eventually stabilize the methylated oncogene mRNAs in inflammation-associated liver cancer. YTHDF2 silenced in human cancer cells or depleted in mouse hepatocytes evoked pro-inflammatory responses and accelerated tumor growth and metastatic progression. Under hypoxia, YTHDF2 processed the decay of m6A-containing interleukin 11 (IL11) and serpin family E member 2 (SERPINE2) mRNAs, which were responsible for the inflammation-mediated malignancy. Reciprocally, YTHDF2 transcription succumbed to hypoxia-inducible factor-2α (HIF-2α). Administration of a HIF-2α antagonist (PT2385) restored YTHDF2-programed epigenetic machinery and repressed liver cancer. Hence, our findings provide a new insight into the mechanism by which hypoxia adapts m6A-mRNA editing to promote cancer.
Project description:Glioblastoma is a universally lethal cancer driven by glioblastoma stem cells (GSCs). Here, we interrogated N6-methyladenosine (m6A) mRNA modifications in GSCs by methyl RNA-immunoprecipitation followed by sequencing (meRIP-seq) and transcriptome analysis, finding transcripts marked by m6A often upregulated. Interrogating m6A regulators, GSCs displayed preferential expression as well as in vitro and in vivo dependency of the m6A reader, YTHDF2, in contrast to normal neural stem cells (NSCs). While YTHDF2 has been reported to destabilize mRNAs, YTHDF2 stabilized the oncogene transcripts, MYC and VEGFA, in GSCs in an m6A-dependent manner. We identified IGFBP3 as a downstream effector of the YTHDF2-MYC axis in GSCs and IGF1/IGF1R inhibitor, Linsitinib, as preferentially targeting YTHDF2-expressing cells, inhibiting the viability of GSCs without affecting NSCs and impairing in vivo glioblastoma growth. Thus, YTHDF2 links RNA epitranscriptomic modifications and GSC growth, laying the foundation for the YTHDF2-MYC-IGFBP3 axis as a specific and novel therapeutic target in glioblastoma.
Project description:The mRNA m6A reader YTHDF2 is overexpressed in a broad spectrum of human acute myeloid leukemias (AML). To understand the role of YTHDF2 in AML, we generated m6A meRIP-seq libraries form Ythdf2fl/fl (Ythdf2CTL) pre-leukemic cells.
Project description:Glioblastoma is a universally lethal cancer driven by glioblastoma stem cells (GSCs). Here, we interrogated N6-methyladenosine (m6A) mRNA modifications in GSCs by methyl RNA-immunoprecipitation followed by sequencing (meRIP-seq) and transcriptome analysis, finding transcripts marked by m6A often upregulated. Interrogating m6A regulators, GSCs displayed preferential expression as well as in vitro and in vivo dependency of the m6A reader, YTHDF2, in contrast to normal neural stem cells (NSCs). While YTHDF2 has been reported to destabilize mRNAs, YTHDF2 stabilized the oncogene transcripts, MYC and VEGFA, in GSCs in an m6A-dependent manner. We identified IGFBP3 as a downstream effector of the YTHDF2-MYC axis in GSCs and IGF1/IGF1R inhibitor, Linsitinib, as preferentially targeting YTHDF2-expressing cells, inhibiting the viability of GSCs without affecting NSCs and impairing in vivo glioblastoma growth. Thus, YTHDF2 links RNA epitranscriptomic modifications and GSC growth, laying the foundation for the YTHDF2-MYC-IGFBP3 axis as a specific and novel therapeutic target in glioblastoma.
Project description:The mRNA m6A reader YTHDF2 is overexpressed in a broad spectrum of human acute myeloid leukemias (AML). To understand the role of YTHDF2 in AML, we generated m6A meRIP-seq libraries form Ythdf2fl/fl; Vav-iCre (Ythdf2CKO) pre-leukemic cells.