Characterization of zygotic genome activation-dependent maternal mRNA clearance in mouse
NUCLEIC ACIDS RESEARCH
Authors: Sha, Qian-Qian; Zhu, Ye-Zhang; Li, Sen; Jiang, Yu; Chen, Lu; Sun, Xiao-Hong; Shen, Li; Ou, Xiang-Hong; Fan, Heng-Yu
Abstract
An important event of the maternal-to-zygotic transition (MZT) in animal embryos is the elimination of a subset of the maternal transcripts that accumulated during oogenesis. In both invertebrates and vertebrates, a maternally encoded mRNA decay pathway (M-decay) acts before zygotic genome activation (ZGA) while a second pathway, which requires zygotic transcription, subsequently clears additional mRNAs (Z-decay). To date the mechanisms that activate the Z-decay pathway in mammalian early embryos have not been investigated. Here, we identify murine maternal transcripts that are degraded after ZGA and show that inhibition of de novo transcription stabilizes these mRNAs in mouse embryos. We show that YAP1-TEAD4 transcription factor-mediated transcription is essential for Z-decay in mouse embryos and that TEAD4-triggered zygotic expression of terminal uridylyltransferases TUT4 and TUT7 and mRNA 3 '-oligouridylation direct Z-decay. Components of the M-decay pathway, including BTG4 and the CCR4-NOT deadenylase, continue to function in Z-decay but require reinforcement from the zygotic factors for timely removal of maternal mRNAs. A long 3 '-UTR and active translation confer resistance of Z-decay transcripts to M-decay during oocyte meiotic maturation. The Z-decay pathway is required for mouse embryo development beyond the four-cell stage and contributes to the developmental competence of preimplantation embryos.
HMGB1-RAGE signaling facilitates Ras-dependent Yap1 expression to drive colorectal cancer stemness and development
MOLECULAR CARCINOGENESIS
Authors: Qian, Fei; Xiao, Jianjia; Gai, Ling; Zhu, Jianwei
Abstract
HMGB1-RAGE signaling plays an integral role in inflammation-driven carcinogenesis. In the present study, we showed that RAGE has direct association with K-Ras following HMGB1 exposure in colorectal cancer (CRC) cells. Immunofluorescence analysis revealed a significant co-localization between RAGE and K-Ras in HMGB1-exposed CRC cells. Moreover, we uncovered that HMGB1-mediated RAGE activation led to Yap1 accumulation in a Ras-dependent mechanism in CRC cells. HMGB1 activated the expression of Yap1 downstream stemness marker proteins CD44 and Sox2 in RAGE- and Ras-dependent manners. Furthermore, HMGB1 exposure led to the proliferation of CRC cells and the expansion of CRC stem cells. RAGE, Yap1 and CD44 were overexpressed in CRC specimens. Linear regression analysis revealed that the expression of RAGE was positively correlated with Yap1 in clinical CRC specimens. Both of RAGE and Yap1 expression were correlated with advanced histological grades, lymph node metastasis and TNM stages. Finally, we revealed that both of RAGE and Yap1 expression could predicted unfavorable prognosis in CRC patients. These findings implicated that HMGB1-RAGE signaling may promote Yap1 activation and CRC progression, shedding new light on the mechanisms underlying inflammation-driven CRC development.