Although NPM1 mutations are frequently found in acute myeloid leukemia patients,therapeutic strategies are scarce and unsuitable for those who cannot tolerate intensive chemotherapy.Here we demonstrated that heliangin...Although NPM1 mutations are frequently found in acute myeloid leukemia patients,therapeutic strategies are scarce and unsuitable for those who cannot tolerate intensive chemotherapy.Here we demonstrated that heliangin,a natural sesquiterpene lactone,exerts favorable therapeutic responses in NPM1 mutant acute myeloid leukemia cells,with no apparent toxicity to normal hematogenous cells,by inhibiting their proliferation,inducing apoptosis,causing cell cycle arrest,and promoting differentiation.In-depth studies on its mode of action using quantitative thiol reactivity platform screening and subsequent molecular biology validation showed that the ribosomal protein S2(RPS2)is the main target of heliangin in treating NPM1 mutant AML.Upon covalent binding to the C222 site of RPS2,the electrophilic moieties of heliangin disrupt pre-rRNA metabolic processes,leading to nucleolar stress,which in turn regulates the ribosomal proteins-MDM2-p53 pathway and stabilizes p53.Clinical data shows that the pre-rRNA metabolic pathway is dysregulated in acute myeloid leukemia patients with the NPM1 mutation,leading to a poor prognosis.We found that RPS2 plays a critical role in regulating this pathway and may be a novel treatment target.Our findings suggest a novel treatment strategy and lead compound for acute myeloid leukemia patients,especially those with NPM1 mutations.展开更多
In Xenopus laevis embryogenesis, fertilized eggs undergo 12 cycles of synchronous divisions and reach the stage called midblastula transition (MBT). It has long been believed that during the first 12 cycles of cleavag...In Xenopus laevis embryogenesis, fertilized eggs undergo 12 cycles of synchronous divisions and reach the stage called midblastula transition (MBT). It has long been believed that during the first 12 cycles of cleavage (pre-MBT stage), transcriptional activity of the zygotic nuclei is totally absent. However, heterogeneous mRNA-like RNA is synthesized in pre-MBT stage embryos, and exogenously-injected bacterial CAT genes with SV40 promoter are expressed from the cleavage stage. Nevertheless, the synthesis of rRNA as detected by rRNA-specific2’-O-methylation does not take place in pre-MBT embryos and starts only from the latter half of the MBT stage, corroborating the fact that formation of definitive nucleoli as well as the transcription of microinjected rRNA genes starts only at and after MBT stage. Thus, while mRNA-like RNA synthesis occurs from pre-MBT stage, synthesis of rRNA is controlled in the way that transcription of rRNA genes is totally silent during pre-MBT stage and is initiated only at the latter half of MBT stage. Once initiated, the rate of the synthesis of rRNA is constant throughout later stages on a per-cell basis. We searched substances which are responsible for the transcriptional silence of rRNA genes during the pre-MBT stage. Weak bases such as ammonium ion and amines selectively inhibited rRNA synthesis at the transcriptional level in post-MBT stage embryo cells. Since we found that the level of ammonia extracted from embryos is much higher in pre-MBT embryos than in post-MBT embryos, we suggest that weak bases like ammonium ion could be responsible for the transcriptional silence of rRNA genes by slightly increasing intracellular pH during the pre-MBT.展开更多
Ribosome biogenesis,which takes place mainly in the nucleolus,involves coordinated expression of preribosomal RNAs(pre-rRNAs)and ribosomal proteins,pre-rRNA processing,and subunit assembly with the aid of numerous ass...Ribosome biogenesis,which takes place mainly in the nucleolus,involves coordinated expression of preribosomal RNAs(pre-rRNAs)and ribosomal proteins,pre-rRNA processing,and subunit assembly with the aid of numerous assembly factors.Our previous study showed that the Arabidopsis thaliana protein arginine methyltransferase AtPRMT3 regulates pre-rRNA processing;however,the underlying molecular mechanism remains unknown.Here,we report that AtPRMT3 interacts with Ribosomal Protein S2(RPS2),facilitating processing of the 90S/Small Subunit(SSU)processome and repressing nucleolar stress.We isolated an intragenic suppressor of atprmt3-2,which rescues the developmental defects of atprmt3-2 while produces a putative truncated AtPRMT3 protein bearing the entire N-terminus but lacking an intact enzymatic activity domain We further identified RPS2 as an interacting partner of AtPRMT3,and found that loss-of-function rps2a2b mutants were phenotypically reminiscent of atprmt3,showing pleiotropic developmental defects and aberrant pre-rRNA processing.RPS2B binds directly to pre-rRNAs in the nucleus,and such binding is enhanced in atprmt3-2.Consistently,multiple components of the 90S/SSU processome were more enriched by RPS2B in atprmt3-2,which accounts for early pre-rRNA processing defects and results in nucleolar stress.Collectively,our study uncovered a novel mechanism by which AtPRMT3 cooperates with RPS2B to facilitate the dynamic assembly/disassembly of the 90S/SSU processome during ribosome biogenesis and repress nucleolar stress.展开更多
基金supported by grants from the National Natural Science Foundation of China(82074067)Natural Science Foundation of Jiangsu Province China(BK20181419,China)Natural Foundation of Jiangsu Higher Education Institutions of China(19KJA310006)。
文摘Although NPM1 mutations are frequently found in acute myeloid leukemia patients,therapeutic strategies are scarce and unsuitable for those who cannot tolerate intensive chemotherapy.Here we demonstrated that heliangin,a natural sesquiterpene lactone,exerts favorable therapeutic responses in NPM1 mutant acute myeloid leukemia cells,with no apparent toxicity to normal hematogenous cells,by inhibiting their proliferation,inducing apoptosis,causing cell cycle arrest,and promoting differentiation.In-depth studies on its mode of action using quantitative thiol reactivity platform screening and subsequent molecular biology validation showed that the ribosomal protein S2(RPS2)is the main target of heliangin in treating NPM1 mutant AML.Upon covalent binding to the C222 site of RPS2,the electrophilic moieties of heliangin disrupt pre-rRNA metabolic processes,leading to nucleolar stress,which in turn regulates the ribosomal proteins-MDM2-p53 pathway and stabilizes p53.Clinical data shows that the pre-rRNA metabolic pathway is dysregulated in acute myeloid leukemia patients with the NPM1 mutation,leading to a poor prognosis.We found that RPS2 plays a critical role in regulating this pathway and may be a novel treatment target.Our findings suggest a novel treatment strategy and lead compound for acute myeloid leukemia patients,especially those with NPM1 mutations.
文摘In Xenopus laevis embryogenesis, fertilized eggs undergo 12 cycles of synchronous divisions and reach the stage called midblastula transition (MBT). It has long been believed that during the first 12 cycles of cleavage (pre-MBT stage), transcriptional activity of the zygotic nuclei is totally absent. However, heterogeneous mRNA-like RNA is synthesized in pre-MBT stage embryos, and exogenously-injected bacterial CAT genes with SV40 promoter are expressed from the cleavage stage. Nevertheless, the synthesis of rRNA as detected by rRNA-specific2’-O-methylation does not take place in pre-MBT embryos and starts only from the latter half of the MBT stage, corroborating the fact that formation of definitive nucleoli as well as the transcription of microinjected rRNA genes starts only at and after MBT stage. Thus, while mRNA-like RNA synthesis occurs from pre-MBT stage, synthesis of rRNA is controlled in the way that transcription of rRNA genes is totally silent during pre-MBT stage and is initiated only at the latter half of MBT stage. Once initiated, the rate of the synthesis of rRNA is constant throughout later stages on a per-cell basis. We searched substances which are responsible for the transcriptional silence of rRNA genes during the pre-MBT stage. Weak bases such as ammonium ion and amines selectively inhibited rRNA synthesis at the transcriptional level in post-MBT stage embryo cells. Since we found that the level of ammonia extracted from embryos is much higher in pre-MBT embryos than in post-MBT embryos, we suggest that weak bases like ammonium ion could be responsible for the transcriptional silence of rRNA genes by slightly increasing intracellular pH during the pre-MBT.
基金This work was supported by grants from the National Natural Science Foundation of China(31788103 and 91540203 to X.Cao,31770874 to C.L.,31900932 to R.H.,and 31701096 to J.S.),Chinathe Strategic Priority Research Program of Chinese Academy of Sciences(XDB27030201 to X.Cao),China+1 种基金the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDY-SSW-SMC022 to X.Cao),Chinathe State Key Laboratory of Plant Genomics,China.
文摘Ribosome biogenesis,which takes place mainly in the nucleolus,involves coordinated expression of preribosomal RNAs(pre-rRNAs)and ribosomal proteins,pre-rRNA processing,and subunit assembly with the aid of numerous assembly factors.Our previous study showed that the Arabidopsis thaliana protein arginine methyltransferase AtPRMT3 regulates pre-rRNA processing;however,the underlying molecular mechanism remains unknown.Here,we report that AtPRMT3 interacts with Ribosomal Protein S2(RPS2),facilitating processing of the 90S/Small Subunit(SSU)processome and repressing nucleolar stress.We isolated an intragenic suppressor of atprmt3-2,which rescues the developmental defects of atprmt3-2 while produces a putative truncated AtPRMT3 protein bearing the entire N-terminus but lacking an intact enzymatic activity domain We further identified RPS2 as an interacting partner of AtPRMT3,and found that loss-of-function rps2a2b mutants were phenotypically reminiscent of atprmt3,showing pleiotropic developmental defects and aberrant pre-rRNA processing.RPS2B binds directly to pre-rRNAs in the nucleus,and such binding is enhanced in atprmt3-2.Consistently,multiple components of the 90S/SSU processome were more enriched by RPS2B in atprmt3-2,which accounts for early pre-rRNA processing defects and results in nucleolar stress.Collectively,our study uncovered a novel mechanism by which AtPRMT3 cooperates with RPS2B to facilitate the dynamic assembly/disassembly of the 90S/SSU processome during ribosome biogenesis and repress nucleolar stress.
