METTL3 methylates RNA and regulates the fate of mRNA through its methyltransferase activity.METTL3 enhances RNA translation independently of its catalytic activity.However,the underlying mechanism is still elusive.Her...METTL3 methylates RNA and regulates the fate of mRNA through its methyltransferase activity.METTL3 enhances RNA translation independently of its catalytic activity.However,the underlying mechanism is still elusive.Here,we report that METTL3 is both interacted with and acetylated at lysine 177 by the acetyltransferase PCAF and deacetylated by SIRT3.Neither the methyltransferase activity nor the stability of METTL3 is affected by its acetylation at K177.Importantly,acetylation of METTL3 blocks its interaction with EIF3H,a subunit of the translation initiation factor,thereby reducing mRNA translation efficiency.Interestingly,acetylation of METTL3 responds to oxidative stress.Mechanistically,oxidative stress enhances the interaction of PCAF with METTL3,increases METTL3 acetylation,and suppresses the interaction of METTL3 with EIF3H,thereby decreasing the translation efficiency of ribosomes and inhibiting cell proliferation.Altogether,we suggest a mechanism by which oxidative stress regulates RNA translation efficiency by the modulation of METTL3 acetylation mediated by PCAF.展开更多
Background:Fascin is crucial for cancer cell filopodium formation and tumor metastasis,and is functionally regulated by post-translational modifications.However,whether and how Fascin is regulated by acetylation remai...Background:Fascin is crucial for cancer cell filopodium formation and tumor metastasis,and is functionally regulated by post-translational modifications.However,whether and how Fascin is regulated by acetylation remains unclear.This study explored the regulation of Fascin acetylation and its corresponding roles in filopodium formation and tumor metastasis.Methods:Immunoprecipitation and glutathione-S-transferase pull-down assays were performed to examine the interaction between Fascin and acetyltransferase P300/CBP-associated factor(PCAF),and immunofluorescence was used to investigate their colocalization.An in vitro acetylation assay was performed to identify Fascin acetylation sites by using mass spectrometry.A specific antibody against acetylated Fascin was generated and used to detect the PCAF-mediated Fascin acetylation in esophageal squamous cell carcinoma(ESCC)cells using Western blotting by overexpressing and knocking down PCAF expression.An in vitro cell migration assay was performed,and a xenograft model was established to study in vivo tumor metastasis.Live-cell imaging and fluorescence recovery after photobleaching were used to evaluate the function and dynamics of acetylated Fascin in filopodium formation.The clinical significance of acetylated Fascin and PCAF in ESCC was evaluated using immunohistochemistry.Results:Fascin directly interacted and colocalized with PCAF in the cytoplasm and was acetylated at lysine 471(K471)by PCAF.Using the specific antiAcK471-Fascin antibody,Fascin was found to be acetylated in ESCC cells,and the acetylation level was consequently increased after PCAF overexpression and decreased after PCAF knockdown.Functionally,Fascin-K471 acetylation markedly suppressed in vitro ESCC cell migration and in vivo tumor metastasis,whereas Fascin-K471 deacetylation exhibited a potent oncogenic function.Moreover,Fascin-K471 acetylation reduced filopodial length and density,and lifespan of ESCC cells,while its deacetylation produced the opposite effect.In the filipodium shaft,K471-acetylated Fascin displayed rapid dynamic exchange,suggesting that it remained in its monomeric form owing to its weakened actinbundling activity.Clinically,high levels of AcK471-Fascin in ESCC tissues were strongly associated with prolonged overall survival and disease-free survival of ESCC patients.Conclusions:Fascin interacts directly with PCAF and is acetylated at lysine 471 in ESCC cells.Fascin-K471 acetylation suppressed ESCC cell migration and tumor metastasis by reducing filopodium formation through the impairment of its actin-bundling activity.展开更多
Simulated results from a detailed elementary reaction mechanism for methane-containing species in flames consisting of nitrogen (NOx), C1 or C2 fuels are presented, and compared with reduced mechanism;this mechanism h...Simulated results from a detailed elementary reaction mechanism for methane-containing species in flames consisting of nitrogen (NOx), C1 or C2 fuels are presented, and compared with reduced mechanism;this mechanism have been constructed with the analysis of the rate sensitivity matrix f (PCAF method), and the computational singular perturbation (CSP). The analysis was performed on solutions of unstrained adiabatic premixed flames with detailed chemical kinetics described by GRI 3.0 for methane including NOx formation. A 9-step reduced mechanism for methane has been constructed which reproduces accurately laminar burning velocities, flame temperatures and mass fraction distributions of major species for the whole flammability range. Many steady-state species are also predicted satisfactorily. This mechanism is especially for lean flames. This mechanism is accurate for a wide range of the equivalence ratio (1, 0.9, 0.8, and 0.7) and for pressures as high as 40 atm to 60 atm. For both fuels, the CSP algorithm automatically pointed to the same steady-state species as those identified by laborious analysis or intuition in the literature and the global reactions were similar to well established previous methane-reduced mechanisms. This implies that the method is very well suited for the study of complex mechanisms for heavy hydrocarbon combustion.展开更多
基金supported by the National Key Research and Development Program of China(2022YFA1104003,2021YFC2501003)the National Natural Science Foundation of China(82230094,81972616,81730071)+1 种基金Peking University Medicine Sailing Program for Young Scholars'Scientific&Technological Innovation(BMU2024YFJHPY004)the Fundamental Research Funds for the Central Universities。
文摘METTL3 methylates RNA and regulates the fate of mRNA through its methyltransferase activity.METTL3 enhances RNA translation independently of its catalytic activity.However,the underlying mechanism is still elusive.Here,we report that METTL3 is both interacted with and acetylated at lysine 177 by the acetyltransferase PCAF and deacetylated by SIRT3.Neither the methyltransferase activity nor the stability of METTL3 is affected by its acetylation at K177.Importantly,acetylation of METTL3 blocks its interaction with EIF3H,a subunit of the translation initiation factor,thereby reducing mRNA translation efficiency.Interestingly,acetylation of METTL3 responds to oxidative stress.Mechanistically,oxidative stress enhances the interaction of PCAF with METTL3,increases METTL3 acetylation,and suppresses the interaction of METTL3 with EIF3H,thereby decreasing the translation efficiency of ribosomes and inhibiting cell proliferation.Altogether,we suggest a mechanism by which oxidative stress regulates RNA translation efficiency by the modulation of METTL3 acetylation mediated by PCAF.
基金National Natural Science Foundation of China,Grant/Award Numbers:81872372,81902469Natural Science Foundation of China-Guangdong Joint Fund,Grant/Award Number:U0932001+2 种基金National Cohort of Esophageal Cancer of China,Grant/Award Number:2016YFC0901400China Postdoctoral Science Foundation,Grant/Award Number:2018M6431342020 Li Ka Shing Foundation Cross-Disciplinary Research Grant,Grant/Award Number:2020LKSFG07B。
文摘Background:Fascin is crucial for cancer cell filopodium formation and tumor metastasis,and is functionally regulated by post-translational modifications.However,whether and how Fascin is regulated by acetylation remains unclear.This study explored the regulation of Fascin acetylation and its corresponding roles in filopodium formation and tumor metastasis.Methods:Immunoprecipitation and glutathione-S-transferase pull-down assays were performed to examine the interaction between Fascin and acetyltransferase P300/CBP-associated factor(PCAF),and immunofluorescence was used to investigate their colocalization.An in vitro acetylation assay was performed to identify Fascin acetylation sites by using mass spectrometry.A specific antibody against acetylated Fascin was generated and used to detect the PCAF-mediated Fascin acetylation in esophageal squamous cell carcinoma(ESCC)cells using Western blotting by overexpressing and knocking down PCAF expression.An in vitro cell migration assay was performed,and a xenograft model was established to study in vivo tumor metastasis.Live-cell imaging and fluorescence recovery after photobleaching were used to evaluate the function and dynamics of acetylated Fascin in filopodium formation.The clinical significance of acetylated Fascin and PCAF in ESCC was evaluated using immunohistochemistry.Results:Fascin directly interacted and colocalized with PCAF in the cytoplasm and was acetylated at lysine 471(K471)by PCAF.Using the specific antiAcK471-Fascin antibody,Fascin was found to be acetylated in ESCC cells,and the acetylation level was consequently increased after PCAF overexpression and decreased after PCAF knockdown.Functionally,Fascin-K471 acetylation markedly suppressed in vitro ESCC cell migration and in vivo tumor metastasis,whereas Fascin-K471 deacetylation exhibited a potent oncogenic function.Moreover,Fascin-K471 acetylation reduced filopodial length and density,and lifespan of ESCC cells,while its deacetylation produced the opposite effect.In the filipodium shaft,K471-acetylated Fascin displayed rapid dynamic exchange,suggesting that it remained in its monomeric form owing to its weakened actinbundling activity.Clinically,high levels of AcK471-Fascin in ESCC tissues were strongly associated with prolonged overall survival and disease-free survival of ESCC patients.Conclusions:Fascin interacts directly with PCAF and is acetylated at lysine 471 in ESCC cells.Fascin-K471 acetylation suppressed ESCC cell migration and tumor metastasis by reducing filopodium formation through the impairment of its actin-bundling activity.
文摘Simulated results from a detailed elementary reaction mechanism for methane-containing species in flames consisting of nitrogen (NOx), C1 or C2 fuels are presented, and compared with reduced mechanism;this mechanism have been constructed with the analysis of the rate sensitivity matrix f (PCAF method), and the computational singular perturbation (CSP). The analysis was performed on solutions of unstrained adiabatic premixed flames with detailed chemical kinetics described by GRI 3.0 for methane including NOx formation. A 9-step reduced mechanism for methane has been constructed which reproduces accurately laminar burning velocities, flame temperatures and mass fraction distributions of major species for the whole flammability range. Many steady-state species are also predicted satisfactorily. This mechanism is especially for lean flames. This mechanism is accurate for a wide range of the equivalence ratio (1, 0.9, 0.8, and 0.7) and for pressures as high as 40 atm to 60 atm. For both fuels, the CSP algorithm automatically pointed to the same steady-state species as those identified by laborious analysis or intuition in the literature and the global reactions were similar to well established previous methane-reduced mechanisms. This implies that the method is very well suited for the study of complex mechanisms for heavy hydrocarbon combustion.
