Regulation of cell fate requires the establishment and erasure of 5-methylcytosine(5mC) in genomic DNA.The formation of 5mC is achieved by DNA cytosine methyltransferases(DNMTs),whereas the removal of5mC can be accomp...Regulation of cell fate requires the establishment and erasure of 5-methylcytosine(5mC) in genomic DNA.The formation of 5mC is achieved by DNA cytosine methyltransferases(DNMTs),whereas the removal of5mC can be accomplished by various pathways.Aside from ten-eleven translocation(TET)-mediated oxidation of 5mC followed by thymine DNA glycosylase(TDG)-initiated base excision repair(BER),the direct deformylation of 5-formylcytosine(5fC) and decarboxylation of 5-carboxylcytosine(5caC) have also been discovered as the novel DNA demethylation pathways.Although these novel demethylation pathways have been identified in stem cells and somatic cells,their precise roles in regulating cell fate remain unclear.Here,we differentiate mouse embryonic stem cells(mESCs) into mouse embryoid bodies(mEBs),followed by further differentiation into mouse neural stem cells(mNSCs) and finally into mouse neurons(mNeurons).During this sequential differentiation process,we employ probe molecules,namely2'-fluorinated 5-formylcytidine(F-5fC) and 2'-fluorinated 5-carboxyldeoxycytidine(F-5caC),for metabolic labeling.The results of mass spectrometry(MS) analysis demonstrate the deformylation and decarboxylation activities are progressively decreased and increased respectively during differentiation process,and this opposite demethylation tendency is not associated with DNMTs and TETs.展开更多
Manganese(Ⅲ)-peroxo complexes are invoked as key intermediates in the enzymatic cycles of Mncontaining enzymes, and the synthesis of reactive manganese(Ⅲ)-peroxo complexes with rationally designed ligand has been of...Manganese(Ⅲ)-peroxo complexes are invoked as key intermediates in the enzymatic cycles of Mncontaining enzymes, and the synthesis of reactive manganese(Ⅲ)-peroxo complexes with rationally designed ligand has been of great interest in the communities of bioinorganic and biomimetic chemistry.Herein, we designed a novel pentadentate aminobenzimidazole ligand and obtained its manganese(Ⅱ)complex, which was successfully applied in the synthesis of a reactive manganese(Ⅲ)-peroxo complex by treatment with hydrogen peroxide in the presence of triethylamine. The manganese(Ⅲ)-peroxo complex was well characterized with various spectroscopic techniques, including ultraviolet-visible(UV-vis)spectrophotometry, coldspray ionization time-of-flight mass spectrometry(CSI-TOF MS), and continuous wave electron paramagnetic resonance(CW-EPR) spectroscopy. Besides, its reactivity in aldehyde deformylation was investigated, demonstrating second-order kinetics in the reaction with 2-phenylpropionaldehyde and affording acetophenone as the sole product.展开更多
We report a substrate-dependent annulation system where 6-substituents of 2H-1,4-benzoxazines dictate divergent pathways with ynamides.Non-methoxy substrates undergo TBSOTf/Zn(OTf)_(2)-catalyzed[2+2]annulation/ring ex...We report a substrate-dependent annulation system where 6-substituents of 2H-1,4-benzoxazines dictate divergent pathways with ynamides.Non-methoxy substrates undergo TBSOTf/Zn(OTf)_(2)-catalyzed[2+2]annulation/ring expansion to form 2H-1,6-benzoxazocines,while 6-methoxy derivatives preferentially yield 4-aminoquinolines via a TBSOTf-catalyzed[4+2]annulation/deformylation pathway.This electronic effect-driven selectivity operates under mild conditions with high fidelity.The method provides orthogonal access to two medicinally important heterocycle classes from identical precursors,features broad functional group tolerance,demonstrates scalability(up to 1 mmol scale),and eliminates the need for transition metals.The selectivity may originate from the differential stabilization of intermediates by the 6-substituent.展开更多
基金supported by the National Key R&D Program of China (Nos.2022YFC3400700,2022YFA0806600)the National Natural Science Foundation of China (No.22074110)+3 种基金Guangdong Basic and Applied Basic Research Foundation (No.2022A1515110550)Central Public-interest Scientific Institution Basal Research Fund,South China Sea Fisheries Research Institute,CAFS (No.2021TS02)Guangzhou Basic and Applied Basic Research Foundation (No.2023A04J1337)Central Public-interest Scientific Institution Basal Research Fund,CAFS (No.2023TD78)。
文摘Regulation of cell fate requires the establishment and erasure of 5-methylcytosine(5mC) in genomic DNA.The formation of 5mC is achieved by DNA cytosine methyltransferases(DNMTs),whereas the removal of5mC can be accomplished by various pathways.Aside from ten-eleven translocation(TET)-mediated oxidation of 5mC followed by thymine DNA glycosylase(TDG)-initiated base excision repair(BER),the direct deformylation of 5-formylcytosine(5fC) and decarboxylation of 5-carboxylcytosine(5caC) have also been discovered as the novel DNA demethylation pathways.Although these novel demethylation pathways have been identified in stem cells and somatic cells,their precise roles in regulating cell fate remain unclear.Here,we differentiate mouse embryonic stem cells(mESCs) into mouse embryoid bodies(mEBs),followed by further differentiation into mouse neural stem cells(mNSCs) and finally into mouse neurons(mNeurons).During this sequential differentiation process,we employ probe molecules,namely2'-fluorinated 5-formylcytidine(F-5fC) and 2'-fluorinated 5-carboxyldeoxycytidine(F-5caC),for metabolic labeling.The results of mass spectrometry(MS) analysis demonstrate the deformylation and decarboxylation activities are progressively decreased and increased respectively during differentiation process,and this opposite demethylation tendency is not associated with DNMTs and TETs.
基金financially supported by the National Natural Science Foundation of China(No.21473226)Natural Science Foundation of Jiangsu Province(No.BK20161261).We acknowledge Prof
文摘Manganese(Ⅲ)-peroxo complexes are invoked as key intermediates in the enzymatic cycles of Mncontaining enzymes, and the synthesis of reactive manganese(Ⅲ)-peroxo complexes with rationally designed ligand has been of great interest in the communities of bioinorganic and biomimetic chemistry.Herein, we designed a novel pentadentate aminobenzimidazole ligand and obtained its manganese(Ⅱ)complex, which was successfully applied in the synthesis of a reactive manganese(Ⅲ)-peroxo complex by treatment with hydrogen peroxide in the presence of triethylamine. The manganese(Ⅲ)-peroxo complex was well characterized with various spectroscopic techniques, including ultraviolet-visible(UV-vis)spectrophotometry, coldspray ionization time-of-flight mass spectrometry(CSI-TOF MS), and continuous wave electron paramagnetic resonance(CW-EPR) spectroscopy. Besides, its reactivity in aldehyde deformylation was investigated, demonstrating second-order kinetics in the reaction with 2-phenylpropionaldehyde and affording acetophenone as the sole product.
基金the Natural Science Foundation of Henan Province(No.252300420229)for financial support.
文摘We report a substrate-dependent annulation system where 6-substituents of 2H-1,4-benzoxazines dictate divergent pathways with ynamides.Non-methoxy substrates undergo TBSOTf/Zn(OTf)_(2)-catalyzed[2+2]annulation/ring expansion to form 2H-1,6-benzoxazocines,while 6-methoxy derivatives preferentially yield 4-aminoquinolines via a TBSOTf-catalyzed[4+2]annulation/deformylation pathway.This electronic effect-driven selectivity operates under mild conditions with high fidelity.The method provides orthogonal access to two medicinally important heterocycle classes from identical precursors,features broad functional group tolerance,demonstrates scalability(up to 1 mmol scale),and eliminates the need for transition metals.The selectivity may originate from the differential stabilization of intermediates by the 6-substituent.
