ABSTRACT: 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: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: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: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: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:The METTL3-METTL14 complex, as the "writer" of N6-methyladenosine (m6A), plays an important role in many biological processes. Previous studies have shown that overexpression of Mettl3 can increase the level of m6A and promotes somatic cell reprogramming. Here, we demonstrate that Mettl14, another component of the methyltransferase (MTase) complex, can significantly enhance the generation of induced pluripotent stem cells (iPSCs) in m6A independent manner. Cooperating with Oct4, Sox2, Klf4 and c-Myc (OSKM), Mettl14 transiently increased the senescence-associated secretory phenotype (SASP) gene expression in the non-reprogramming cells at the late reprogramming stage. The conditional medium in reprogramming intermediates overexpressing Mettl4 or its mutant could enhanced the reprogramming, so do IL-6, a component of SASP. Corespondingly, blocking of SASP using senolytic agent or NF-κB inhibitor impairs the effect of Mettl14 on reprogramming. . Our work highlights the m6A independent function of Mettl14 and provides new insight into the interplay between senescence and reprogramming in vitro.
Project description:N6-methyladenosine (m6A) methylation of mRNA by the methyltransferase complex (MTC), with core components including METTL3-METTL14 heterodimers and Wilms’ tumor 1-associated protein (WTAP), contributes to breast tumorigenesis, but the mechanism of MTC assembly remains elusive. Here, we identify a novel cleaved form METTL3a (residues 239-580 of METTL3), that is highly expressed in breast cancer. Furthermore, we find that both METTL3a and full-length METTL3 are required for MTC assembly, RNA m6A deposition, as well as cancer cell proliferation. Mechanistically, we find that METTL3a is required for METTL3-METTL3 interaction, which is a prerequisite step for recruitment of WTAP in MTC assembly. Analysis of m6A sequencing data shows that depletion of METTL3a globally disrupts m6A methylation, and METTL3a mediates mTOR activation via m6A-mediated suppression of TMEM127 expression. Consequently, we find that METTL3 cleavage is mediated by proteasome in an mTOR-dependent manner, revealing positive regulatory feedback between METTL3a and mTOR signaling. Our findings reveal METTL3a as an important component for MTC assembly, and suggest the METTL3a-mTOR axis as a potential therapeutic target for breast cancer.
Project description:Cellular senescence is a stable state of growth arrest that emerges as a response to stress. The methyltransferase complex (MTC) has been shown to facilitate the expression of the senescence-associated secretion phenotype (SASP) factors via genome-wide redistribution. However, whether and how MTC impacts on the three-dimensional (3D) chromatin organization and its functional implications during senescence remain largely unknown. Here we show that the MTC complex coordinates its enzymatic activity-dependent and -independent functions to enforce cellular senescence. Specifically, METTL3-mediated chromatin loops induce Hexokinase 2 (HK2) expression during senescence. The elevated HK2 expression subsequently promotes liquid-liquid phase separation (LLPS), manifesting as stress granules. These phase-separated stress granules act as reservoirs to sequester cell-cycle related mRNAs harboring polymethylated m6A sites, impeding their efficient translation. Overall, we uncover a mechanism by which senescent cells utilize phase-separated stress granules, facilitated by MTC-mediated HK2 activation, to sequester cell-cycle related mRNAs in governing senescence-associated stable growth arrest.
Project description:Cellular senescence is a stable state of growth arrest that emerges as a response to stress. The methyltransferase complex (MTC) has been shown to facilitate the expression of the senescence-associated secretion phenotype (SASP) factors via genome-wide redistribution. However, whether and how MTC impacts on the three-dimensional (3D) chromatin organization and its functional implications during senescence remain largely unknown. Here we show that the MTC complex coordinates its enzymatic activity-dependent and -independent functions to enforce cellular senescence. Specifically, METTL3-mediated chromatin loops induce Hexokinase 2 (HK2) expression during senescence. The elevated HK2 expression subsequently promotes liquid-liquid phase separation (LLPS), manifesting as stress granules. These phase-separated stress granules act as reservoirs to sequester cell-cycle related mRNAs harboring polymethylated m6A sites, impeding their efficient translation. Overall, we uncover a mechanism by which senescent cells utilize phase-separated stress granules, facilitated by MTC-mediated HK2 activation, to sequester cell-cycle related mRNAs in governing senescence-associated stable growth arrest.
Project description:Cellular senescence is a stable state of growth arrest that emerges as a response to stress. The methyltransferase complex (MTC) has been shown to facilitate the expression of the senescence-associated secretion phenotype (SASP) factors via genome-wide redistribution. However, whether and how MTC impacts on the three-dimensional (3D) chromatin organization and its functional implications during senescence remain largely unknown. Here we show that the MTC complex coordinates its enzymatic activity-dependent and -independent functions to enforce cellular senescence. Specifically, METTL3-mediated chromatin loops induce Hexokinase 2 (HK2) expression during senescence. The elevated HK2 expression subsequently promotes liquid-liquid phase separation (LLPS), manifesting as stress granules. These phase-separated stress granules act as reservoirs to sequester cell-cycle related mRNAs harboring polymethylated m6A sites, impeding their efficient translation. Overall, we uncover a mechanism by which senescent cells utilize phase-separated stress granules, facilitated by MTC-mediated HK2 activation, to sequester cell-cycle related mRNAs in governing senescence-associated stable growth arrest.
Project description:Cellular senescence is a stable state of growth arrest that emerges as a response to stress. The methyltransferase complex (MTC) has been shown to facilitate the expression of the senescence-associated secretion phenotype (SASP) factors via genome-wide redistribution. However, whether and how MTC impacts on the three-dimensional (3D) chromatin organization and its functional implications during senescence remain largely unknown. Here we show that the MTC complex coordinates its enzymatic activity-dependent and -independent functions to enforce cellular senescence. Specifically, METTL3-mediated chromatin loops induce Hexokinase 2 (HK2) expression during senescence. The elevated HK2 expression subsequently promotes liquid-liquid phase separation (LLPS), manifesting as stress granules. These phase-separated stress granules act as reservoirs to sequester cell-cycle related mRNAs harboring polymethylated m6A sites, impeding their efficient translation. Overall, we uncover a mechanism by which senescent cells utilize phase-separated stress granules, facilitated by MTC-mediated HK2 activation, to sequester cell-cycle related mRNAs in governing senescence-associated stable growth arrest.