Vestibular hair cells(HCs)in the inner ear,crucial for balance and spatial orientation,are classified into type I and type II subtypes,but the mechanisms regulating their differentiation remain unclear.In this study,w...Vestibular hair cells(HCs)in the inner ear,crucial for balance and spatial orientation,are classified into type I and type II subtypes,but the mechanisms regulating their differentiation remain unclear.In this study,we examined the role of Pou4f3,an important transcription factor,in vestibular HC differentiation using Pou4f3^(DTR/DTR)(deficient)and Pou4f3CreER/CreER(knockout)mouse models.In Pou4f3-deficient mice,the HC number decreased,and immature HCs failed to develop type I characteristics,indicating a developmental arrest.While type II HCs differentiated normally,Pou4f3 deficiency disrupted HC bundle formation and cell polarity.Findings from knockout models further confirmed the essential role of Pou4f3 in vestibular HC subtype specification.This study underscores the critical role of Pou4f3 in determining vestibular HC subtypes and offers insights into potential strategies for restoring vestibular function through HC regeneration.展开更多
Objectives:The eukaryotic initiation factor 4F(eIF4F)translation initiation complex inhibitors(eIF4Fi)were recently found to hyperactivate extracellular signal-regulated kinases 1/2(ERK1/2)signals,which contribute to ...Objectives:The eukaryotic initiation factor 4F(eIF4F)translation initiation complex inhibitors(eIF4Fi)were recently found to hyperactivate extracellular signal-regulated kinases 1/2(ERK1/2)signals,which contribute to acquired resistance to BRAF(B-Raf proto-oncogene,serine/threonine kinase)inhibitors in melanoma.This present study aims to elucidate how to overcome the resistance of the eIF4Fi in BRAFV600E mutant melanoma cells and explore the underlying mechanisms.Methods:Melanoma A375(vemurafenib[VEM]-sensitive)and A375R(VEM-resistant)cells were exposed to eIF4Fi RocA at varying doses and durations in vitro.We investigated the impact of RocA on the activity of ERK1/2,AKT serine/threonine kinase 1(AKT1),eIF4E,and enhancer of zeste homolog 2(EZH2).We then examined the impact of RocA on pro-apoptotic BH3-only proteins and proliferative proteins.We subsequently determined the effect of combined eIF4Fi,AKT1 inhibitor,EZH2 inhibitor or VEM on tumor growth in vitro and in vivo.Results:RocA inhibited proliferation and induced apoptosis in A375 cells,but inhibited proliferation in A375R cells.RocA rapidly reactivated ERK1/2 at 3 h and returned to baseline levels at 48 h.However,eIF4E and AKT1 activation began at 12 h and peaked at 48 h.ERK1/2 positively regulated EZH2 and EZH2-dependent expression of c-Fos and EGR1,while AKT1 negatively regulated c-Myc,c-Jun,and BMF,but positively regulated eIF4E.RocA downregulated ERK1/2(or EZH2,AKT1,and eIF4E)independent bcl-2 and Mcl-1 expression.AKT1i enhanced RocA-induced cell apoptosis,while EZH2i reduced RocA-induced cell proliferation.Combined CR-1-31-B,EZH2i,and AKT1i effectively overcame resistance to RocA and VEM resistance both in vitro and in vivo.Conclusion:The eIF4F complex inhibitor reactivates ERK1/2-EZH2 and AKT1 signaling pathways,resulting in resistance to both eIF4Fi and VEM.Combined administration of an eIF4Fi with EZH2 and AKT1 inhibitors effectively enhances sensitivity to both eIF4F complex and BRAF inhibitors.展开更多
基金supported by the National Natural Science Foundation of China(82271159,82071049,82425018,and 82101219)the STI2030-Major Projects(2022ZD0205400).
文摘Vestibular hair cells(HCs)in the inner ear,crucial for balance and spatial orientation,are classified into type I and type II subtypes,but the mechanisms regulating their differentiation remain unclear.In this study,we examined the role of Pou4f3,an important transcription factor,in vestibular HC differentiation using Pou4f3^(DTR/DTR)(deficient)and Pou4f3CreER/CreER(knockout)mouse models.In Pou4f3-deficient mice,the HC number decreased,and immature HCs failed to develop type I characteristics,indicating a developmental arrest.While type II HCs differentiated normally,Pou4f3 deficiency disrupted HC bundle formation and cell polarity.Findings from knockout models further confirmed the essential role of Pou4f3 in vestibular HC subtype specification.This study underscores the critical role of Pou4f3 in determining vestibular HC subtypes and offers insights into potential strategies for restoring vestibular function through HC regeneration.
文摘Objectives:The eukaryotic initiation factor 4F(eIF4F)translation initiation complex inhibitors(eIF4Fi)were recently found to hyperactivate extracellular signal-regulated kinases 1/2(ERK1/2)signals,which contribute to acquired resistance to BRAF(B-Raf proto-oncogene,serine/threonine kinase)inhibitors in melanoma.This present study aims to elucidate how to overcome the resistance of the eIF4Fi in BRAFV600E mutant melanoma cells and explore the underlying mechanisms.Methods:Melanoma A375(vemurafenib[VEM]-sensitive)and A375R(VEM-resistant)cells were exposed to eIF4Fi RocA at varying doses and durations in vitro.We investigated the impact of RocA on the activity of ERK1/2,AKT serine/threonine kinase 1(AKT1),eIF4E,and enhancer of zeste homolog 2(EZH2).We then examined the impact of RocA on pro-apoptotic BH3-only proteins and proliferative proteins.We subsequently determined the effect of combined eIF4Fi,AKT1 inhibitor,EZH2 inhibitor or VEM on tumor growth in vitro and in vivo.Results:RocA inhibited proliferation and induced apoptosis in A375 cells,but inhibited proliferation in A375R cells.RocA rapidly reactivated ERK1/2 at 3 h and returned to baseline levels at 48 h.However,eIF4E and AKT1 activation began at 12 h and peaked at 48 h.ERK1/2 positively regulated EZH2 and EZH2-dependent expression of c-Fos and EGR1,while AKT1 negatively regulated c-Myc,c-Jun,and BMF,but positively regulated eIF4E.RocA downregulated ERK1/2(or EZH2,AKT1,and eIF4E)independent bcl-2 and Mcl-1 expression.AKT1i enhanced RocA-induced cell apoptosis,while EZH2i reduced RocA-induced cell proliferation.Combined CR-1-31-B,EZH2i,and AKT1i effectively overcame resistance to RocA and VEM resistance both in vitro and in vivo.Conclusion:The eIF4F complex inhibitor reactivates ERK1/2-EZH2 and AKT1 signaling pathways,resulting in resistance to both eIF4Fi and VEM.Combined administration of an eIF4Fi with EZH2 and AKT1 inhibitors effectively enhances sensitivity to both eIF4F complex and BRAF inhibitors.
