METTL16 promotes translation and lung tumorigenesis by sequestering cytoplasmic eIF4E2.

N6-methyladenosine (m6A) plays crucial roles in regulating RNA metabolisms. METTL16 identified as a single-component methyltransferase catalyzes m6A formation in the nucleus; whether it regulates cytoplasmic RNA fate remains unknown. Here, we detected the dual localization of METTL16 in the nucleus and cytoplasm. METTL16 depletion attenuates protein synthesis, but the methyltransferase activity is not required for its translation-promoting function. Mechanistically, we identified an interactor of METTL16, eIF4E2, which represses translation by acting as a competitor of eIF4E. The METTL16-eIF4E2 interaction impedes the recruitment of eIF4E2 to 5' cap structure, promoting the cap recognition by eIF4E and selective protein synthesis. Depletion of METTL16 suppresses lung tumorigenesis by downregulating the translation of key oncogenes. Collectively, our study reports a role of METTL16 in modulating translation and provides a therapeutic target for lung cancer treatment.

Huangjia Ruangan Granule Inhibits Inflammation in a Rat Model with Liver Fibrosis by Regulating TNF/MAPK and NF-κB Signaling Pathways.

The Huangjia Ruangan granule (HJRG) is a clinically effective Kampo formula, which has a significant effect on liver fibrosis and early liver cirrhosis. However, the mechanism underlying HJRG in treating liver fibrosis remains unclear. In this study, carbon tetrachloride (CCl4) was used to induce liver fibrosis in rats to clarify the effect of HJRG on liver fibrosis and its mechanism. Using network pharmacology, the potential mechanism of HJRG was initially explored, and a variety of analyses were performed to verify this mechanism. In the liver fibrosis model, treatment with HJRG can maintain the liver morphology, lower the levels of AST and ALT in the serum, and ameliorate pathological damage. Histopathological examinations revealed that the liver structure was significantly improved and fibrotic changes were alleviated. It can effectively inhibit collagen deposition and the expression of α-SMA, reduce the levels of the rat serum (HA, LN, PC III, and Col IV), and inhibit the expression of desmin, vimentin, and HYP content in the liver. Analyzing the results of network pharmacology, the oxidative stress, inflammation, and the related pathways (primarily the TNF signaling pathway) were identified as the potential mechanism of HJRG against liver fibrosis. Experiments confirmed that HJRG can significantly increase the content of superoxide dismutase and glutathione and reduce the levels of malondialdehyde and myeloperoxidase in the rat liver; in addition, HJRG significantly inhibited the content of proinflammatory cytokines (TNF-α, IL-1ß, and IL-6) and reduced the expression of inflammatory regulators (Cox2 and iNOS). Meanwhile, treatment with HJRG inhibited the phosphorylation of NF-κB P65, IκBα, ERK, JNK, and MAPK P38. Moreover, HJRG treatment reversed the increased expression of TNFR1. The Huangjia Ruangan granule can effectively inhibit liver fibrosis through antioxidation, suppressing liver inflammation by regulating the TNF/MAPK and NF-κB signaling pathways, thereby preventing the effect of liver fibrosis.

Differential roles of YTHDF1 and YTHDF3 in embryonic stem cell-derived cardiomyocyte differentiation.

N6-methyladenosine (m6A) has emerged as a crucial epitranscriptomic mark which regulates a broad spectrum of physiological processes including stem cell differentiation. m6A-binding YTHDF proteins have recently been proposed to mediate differentiation of leukemia cell in a redundant manner. However, whether these proteins play semblable roles in pluripotent stem cell remain largely unknown. Here, we showed the differential functions of YTHDF1 and YTHDF3 in controlling the differentiation of embryonic stem cells (ESCs). Depletion of YTHDF3 in ESCs resulted in loss of pluripotency with accelerated expressions of marker genes involved in formation of three germ layers. Phenotypic and transcriptomic analyses revealed that loss of YTHDF1 led to dramatic impairment of cardiomyocytes (CMs) differentiation, accompanied by downregulated CM-specific genes. While, knockdown of YTHDF3 accelerated differentiation through facilitating the expressions of CM-specific gene. Notably, YTHDF3 appears to modulate cellular differentiation partially through suppression of YTHDF1, supporting the distinguishable but interrelated roles of YTHDF1 and YTHDF3 in cell fate determination.