Inhibition of guanosine triphosphate（GTP） and cytidine triphosphate（CTP） biosynthetic pathways induces cells to assemble rod/ring（RR） structures,also named cytoophidia,which consist of the enzymes cytidine triph...Inhibition of guanosine triphosphate（GTP） and cytidine triphosphate（CTP） biosynthetic pathways induces cells to assemble rod/ring（RR） structures,also named cytoophidia,which consist of the enzymes cytidine triphosphate synthase（CTPS） and inosine-50-monophosphate dehydrogenase 2（IMPDH2）.We aim to explore the interaction of CTPS and IMPDH2 in the generation of RR structures.He La and COS-7 cells were cultured in normal conditions or in the presence of 6-diazo-5-oxo-L-norleucine（DON）,ribavirin,or mycophenolic acid（MPA）.Over 90% of DON-treated cells presented RR structures.In He La cells,35% of the RR structures were positive for IMPDH2 alone,26% were CTPS alone,and 31% were IMPDH2/CTPS mixed,while in COS-7 cells,42% of RR were IMPDH2 alone,41% were CTPS alone,and 10% were IMPDH2/CTPS mixed.Ribavirin and MPA treatments induced only IMPDH2-based RR.Cells were also transfected with an N-terminal hemagglutinin（NHA）-tagged CTPS1 construct.Over 95% of NHA-CTPS1 transfected cells with DON treatment presented IMPDH2-based RR and almost 100% presented CTPS1-based RR;when treated with ribavirin,over 94% of transfected cells presented IMPDH2-based RR and 37% presented CTPS1-based RR,whereas 2% of untreated transfected cells presented IMPDH2-based RR and 28% presented CTPS1-based RR.These results may help in understanding the relationship between CTP and GTP biosynthetic pathways,especially concerning the formation of filamentous RR structures.展开更多
Inflammatory bowel disease(IBD)is a chronic inflammatory disorder of the gastrointestinal tract,which increases the incidence of colorectal cancer(CRC).In the pathophysiology of IBD,ubiquitination/deubiquitination pla...Inflammatory bowel disease(IBD)is a chronic inflammatory disorder of the gastrointestinal tract,which increases the incidence of colorectal cancer(CRC).In the pathophysiology of IBD,ubiquitination/deubiquitination plays a critical regulatory function.Josephin domain containing 2(JOSD2),a deubiquitinating enzyme,controls cell proliferation and carcinogenesis.However,its role in IBD remains unknown.Colitis mice model developed by dextran sodium sulfate(DSS)or colon tissues from individuals with ulcerative colitis and Crohn's disease showed a significant upregulation of JOSD2 expression in the macrophages.JOSD2 deficiency exacerbated the phenotypes of DSS-induced colitis by enhancing colon inflammation.DSS-challenged mice with myeloid-specific JOSD2 deletion developed severe colitis after bone marrow transplantation.Mechanistically,JOSD2 binds to the C-terminal of inosine-5′-monophosphate dehydrogenase 2(IMPDH2)and preferentially cleaves K63-linked polyubiquitin chains at the K134 site,suppressing IMPDH2 activity and preventing activation of nuclear factor kappa B(NF-κB)and inflammation in macrophages.It was also shown that JOSD2 knockout significantly exacerbated increased azoxymethane(AOM)/DSS-induced CRC,and AAV6-mediated JOSD2 overexpression in macrophages prevented the development of colitis in mice.These outcomes reveal a novel role for JOSD2 in colitis through deubiquitinating IMPDH2,suggesting that targeting JOSD2 is a potential strategy for treating IBD.展开更多
With the support by the National Natural Science Foundation of China,a study by the research group led by Prof.Tu Pengfei(屠鹏飞)from the School of Pharmaceutical Sciences,Peking University demonstrates that natural s...With the support by the National Natural Science Foundation of China,a study by the research group led by Prof.Tu Pengfei(屠鹏飞)from the School of Pharmaceutical Sciences,Peking University demonstrates that natural small-molecule sappanone A directly targets IMPDH2to block its activity,展开更多
目的:探讨胃癌化疗耐药形成机制中嘌呤代谢通路关键基因的作用及其调控机制,并评估其临床预测价值。方法:通过生物信息学分析筛选化疗耐药相关差异基因,结合功能富集分析确定嘌呤代谢通路的关键基因,并验证其表达水平及与患者预后的关...目的:探讨胃癌化疗耐药形成机制中嘌呤代谢通路关键基因的作用及其调控机制,并评估其临床预测价值。方法:通过生物信息学分析筛选化疗耐药相关差异基因,结合功能富集分析确定嘌呤代谢通路的关键基因,并验证其表达水平及与患者预后的关系。同时,探索其可能的调控机制,并构建基于关键基因的预后模型。结果:化疗耐药组中嘌呤代谢通路活性显著增强,IMPDH2高表达且与胃癌患者较差预后相关。进一步分析提示c-Myc可能作为IMPDH2的上游转录因子,而KRAS通过MAPK通路上调c-Myc,推测存在c-Myc-IMPDH2-KRAS闭环调控机制。基于IMPDH2及相关基因构建的预后模型,能够有效预测胃癌患者的5年生存率和无病生存率。结论:本研究发现IMPDH2在胃癌化疗耐药中起关键作用,并推测其通过c-Myc-IMPDH2-KRAS闭环机制促进嘌呤代谢重编程及化疗耐药。构建的预后模型具有良好的预测能力,为胃癌精准治疗和个体化管理提供了新思路。Objective: To explore the role and regulatory mechanisms of key genes in the purine metabolism pathway involved in gastric cancer chemotherapy resistance and to evaluate their clinical prognostic value. Methods: Bioinformatics analysis was used to identify chemotherapy resistance-related differentially expressed genes. Functional enrichment analysis was performed to identify key genes in the purine metabolism pathway, followed by validation of their expression levels and association with patient prognosis. Potential regulatory mechanisms were explored, and a prognostic model based on the key genes was constructed. Results: The purine metabolism pathway was significantly upregulated in the chemotherapy-resistant group, with IMPDH2 highly expressed and associated with poor prognosis in gastric cancer patients. Further analysis suggested that c-Myc may act as the upstream transcription factor of IMPDH2, while KRAS may regulate c-Myc via the MAPK pathway, indicating the existence of a c-Myc-IMPDH2-KRAS feedback regulatory loop. A prognostic model based on IMPDH2 and related genes effectively predicted the 5-year overall survival and disease-free survival rates of gastric cancer patients. Conclusion: This study identified IMPDH2 as a key player in gastric cancer chemotherapy resistance and proposed that it may promote purine metabolism reprogramming and chemotherapy resistance via the c-Myc-IMPDH2-KRAS feedback loop. The constructed prognostic model demonstrated good predictive power, offering new insights for precision therapy and personalized management of gastric cancer.展开更多
基金supported by the Brazilian Government Research Foundation CAPES (Coordination for the Improvement of Higher Education Personnel,No.9028-11-0)the Sao Paulo State Research Foundation (Sao Paulo Government agency FAPESP,No.2011/12448-0)both granted to LECA and GDK,and by the research grant from Brazilian Government Agency CNPq (No.305064/2011-8) to LECA
文摘Inhibition of guanosine triphosphate（GTP） and cytidine triphosphate（CTP） biosynthetic pathways induces cells to assemble rod/ring（RR） structures,also named cytoophidia,which consist of the enzymes cytidine triphosphate synthase（CTPS） and inosine-50-monophosphate dehydrogenase 2（IMPDH2）.We aim to explore the interaction of CTPS and IMPDH2 in the generation of RR structures.He La and COS-7 cells were cultured in normal conditions or in the presence of 6-diazo-5-oxo-L-norleucine（DON）,ribavirin,or mycophenolic acid（MPA）.Over 90% of DON-treated cells presented RR structures.In He La cells,35% of the RR structures were positive for IMPDH2 alone,26% were CTPS alone,and 31% were IMPDH2/CTPS mixed,while in COS-7 cells,42% of RR were IMPDH2 alone,41% were CTPS alone,and 10% were IMPDH2/CTPS mixed.Ribavirin and MPA treatments induced only IMPDH2-based RR.Cells were also transfected with an N-terminal hemagglutinin（NHA）-tagged CTPS1 construct.Over 95% of NHA-CTPS1 transfected cells with DON treatment presented IMPDH2-based RR and almost 100% presented CTPS1-based RR;when treated with ribavirin,over 94% of transfected cells presented IMPDH2-based RR and 37% presented CTPS1-based RR,whereas 2% of untreated transfected cells presented IMPDH2-based RR and 28% presented CTPS1-based RR.These results may help in understanding the relationship between CTP and GTP biosynthetic pathways,especially concerning the formation of filamentous RR structures.
基金supported by the National Natural Science Foundation of China(82300589 to Xin Liu,82004042 to Mincong Huang,and 82370244 to Yi Wang)the Zhejiang Provincial Key Scientific Project(2021C03041 to Guang Liang,China).
文摘Inflammatory bowel disease(IBD)is a chronic inflammatory disorder of the gastrointestinal tract,which increases the incidence of colorectal cancer(CRC).In the pathophysiology of IBD,ubiquitination/deubiquitination plays a critical regulatory function.Josephin domain containing 2(JOSD2),a deubiquitinating enzyme,controls cell proliferation and carcinogenesis.However,its role in IBD remains unknown.Colitis mice model developed by dextran sodium sulfate(DSS)or colon tissues from individuals with ulcerative colitis and Crohn's disease showed a significant upregulation of JOSD2 expression in the macrophages.JOSD2 deficiency exacerbated the phenotypes of DSS-induced colitis by enhancing colon inflammation.DSS-challenged mice with myeloid-specific JOSD2 deletion developed severe colitis after bone marrow transplantation.Mechanistically,JOSD2 binds to the C-terminal of inosine-5′-monophosphate dehydrogenase 2(IMPDH2)and preferentially cleaves K63-linked polyubiquitin chains at the K134 site,suppressing IMPDH2 activity and preventing activation of nuclear factor kappa B(NF-κB)and inflammation in macrophages.It was also shown that JOSD2 knockout significantly exacerbated increased azoxymethane(AOM)/DSS-induced CRC,and AAV6-mediated JOSD2 overexpression in macrophages prevented the development of colitis in mice.These outcomes reveal a novel role for JOSD2 in colitis through deubiquitinating IMPDH2,suggesting that targeting JOSD2 is a potential strategy for treating IBD.
文摘With the support by the National Natural Science Foundation of China,a study by the research group led by Prof.Tu Pengfei(屠鹏飞)from the School of Pharmaceutical Sciences,Peking University demonstrates that natural small-molecule sappanone A directly targets IMPDH2to block its activity,
文摘目的:探讨胃癌化疗耐药形成机制中嘌呤代谢通路关键基因的作用及其调控机制,并评估其临床预测价值。方法:通过生物信息学分析筛选化疗耐药相关差异基因,结合功能富集分析确定嘌呤代谢通路的关键基因,并验证其表达水平及与患者预后的关系。同时,探索其可能的调控机制,并构建基于关键基因的预后模型。结果:化疗耐药组中嘌呤代谢通路活性显著增强,IMPDH2高表达且与胃癌患者较差预后相关。进一步分析提示c-Myc可能作为IMPDH2的上游转录因子,而KRAS通过MAPK通路上调c-Myc,推测存在c-Myc-IMPDH2-KRAS闭环调控机制。基于IMPDH2及相关基因构建的预后模型,能够有效预测胃癌患者的5年生存率和无病生存率。结论:本研究发现IMPDH2在胃癌化疗耐药中起关键作用,并推测其通过c-Myc-IMPDH2-KRAS闭环机制促进嘌呤代谢重编程及化疗耐药。构建的预后模型具有良好的预测能力,为胃癌精准治疗和个体化管理提供了新思路。Objective: To explore the role and regulatory mechanisms of key genes in the purine metabolism pathway involved in gastric cancer chemotherapy resistance and to evaluate their clinical prognostic value. Methods: Bioinformatics analysis was used to identify chemotherapy resistance-related differentially expressed genes. Functional enrichment analysis was performed to identify key genes in the purine metabolism pathway, followed by validation of their expression levels and association with patient prognosis. Potential regulatory mechanisms were explored, and a prognostic model based on the key genes was constructed. Results: The purine metabolism pathway was significantly upregulated in the chemotherapy-resistant group, with IMPDH2 highly expressed and associated with poor prognosis in gastric cancer patients. Further analysis suggested that c-Myc may act as the upstream transcription factor of IMPDH2, while KRAS may regulate c-Myc via the MAPK pathway, indicating the existence of a c-Myc-IMPDH2-KRAS feedback regulatory loop. A prognostic model based on IMPDH2 and related genes effectively predicted the 5-year overall survival and disease-free survival rates of gastric cancer patients. Conclusion: This study identified IMPDH2 as a key player in gastric cancer chemotherapy resistance and proposed that it may promote purine metabolism reprogramming and chemotherapy resistance via the c-Myc-IMPDH2-KRAS feedback loop. The constructed prognostic model demonstrated good predictive power, offering new insights for precision therapy and personalized management of gastric cancer.
