Background:Abnormal alternative splicing is frequently associated with carcinogenesis.In B-cell acute lymphoblastic leukemia(B-ALL),double homeobox 4 fused with immunoglobulin heavy chain(DUX4/IGH)can lead to the aber...Background:Abnormal alternative splicing is frequently associated with carcinogenesis.In B-cell acute lymphoblastic leukemia(B-ALL),double homeobox 4 fused with immunoglobulin heavy chain(DUX4/IGH)can lead to the aberrant production of E-26 transformation-specific family related gene abnormal transcript(ERGalt)and other splicing variants.However,the molecular mechanism underpinning this process remains elusive.Here,we aimed to know how DUX4/IGH triggers abnormal splicing in leukemia.Methods:The differential intron retention analysis was conducted to identify novel DUX4/IGH-driven splicing in B-ALL patients.X-ray crystallography,small angle X-ray scattering(SAXS),and analytical ultracentrifugation were used to investigate how DUX4/IGH recognize double DUX4 responsive element(DRE)-DRE sites.The ERGalt biogenesis and B-cell differentiation assays were performed to characterize the DUX4/IGH crosslinking activity.To check whether recombination-activating gene 1/2(RAG1/2)was required for DUX4/IGH-driven splicing,the proximity ligation assay,co-immunoprecipitation,mammalian two hybrid characterizations,in vitro RAG1/2 cleavage,and shRNA knock-down assays were performed.Results:We reported previously unrecognized intron retention events in Ctype lectin domain family 12,member A abnormal transcript(CLEC12Aalt)and chromosome 6 open reading frame 89 abnormal transcript(C6orf89alt),where also harbored repetitive DRE-DRE sites.Supportively,X-ray crystallography and SAXS characterization revealed that DUX4 homeobox domain(HD)1-HD2 might dimerize into a dumbbell-shape trans configuration to crosslink two adjacent DRE sites.Impaired DUX4/IGH-mediated crosslinking abolishes ERGalt,CLEC12Aalt,and C6orf89alt biogenesis,resulting in marked alleviation of its inhibitory effect on B-cell differentiation.Furthermore,we also observed a rare RAG1/2-mediated recombination signal sequence-like DNA edition in DUX4/IGH target genes.Supportively,shRNA knock-down of RAG1/2 in leukemic Reh cells consistently impaired the biogenesis of ERGalt,CLEC12Aalt,and C6orf89alt.Conclusions:All these results suggest that DUX4/IGH-driven DNA crosslinking is required for RAG1/2 recruitment onto the double tandem DRE-DRE sites,catalyzing V(D)J-like recombination and oncogenic splicing in acute lymphoblastic leukemia.展开更多
基金National Natural Science Foundation of China,Grant/Award Numbers:81970132,81770142,81800144,31800642Shanghai Science and Technology Committee,Grant/Award Number:20JC1410600+3 种基金Shanghai Guangci Translational Medical Research Development FoundationShanghai Municipal Education Commission-Gaofeng Clinical Medicine Grant Support,Grant/Award Number:20152504The Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institute of Higher LearningSamuel Waxman Cancer Research Foundation。
文摘Background:Abnormal alternative splicing is frequently associated with carcinogenesis.In B-cell acute lymphoblastic leukemia(B-ALL),double homeobox 4 fused with immunoglobulin heavy chain(DUX4/IGH)can lead to the aberrant production of E-26 transformation-specific family related gene abnormal transcript(ERGalt)and other splicing variants.However,the molecular mechanism underpinning this process remains elusive.Here,we aimed to know how DUX4/IGH triggers abnormal splicing in leukemia.Methods:The differential intron retention analysis was conducted to identify novel DUX4/IGH-driven splicing in B-ALL patients.X-ray crystallography,small angle X-ray scattering(SAXS),and analytical ultracentrifugation were used to investigate how DUX4/IGH recognize double DUX4 responsive element(DRE)-DRE sites.The ERGalt biogenesis and B-cell differentiation assays were performed to characterize the DUX4/IGH crosslinking activity.To check whether recombination-activating gene 1/2(RAG1/2)was required for DUX4/IGH-driven splicing,the proximity ligation assay,co-immunoprecipitation,mammalian two hybrid characterizations,in vitro RAG1/2 cleavage,and shRNA knock-down assays were performed.Results:We reported previously unrecognized intron retention events in Ctype lectin domain family 12,member A abnormal transcript(CLEC12Aalt)and chromosome 6 open reading frame 89 abnormal transcript(C6orf89alt),where also harbored repetitive DRE-DRE sites.Supportively,X-ray crystallography and SAXS characterization revealed that DUX4 homeobox domain(HD)1-HD2 might dimerize into a dumbbell-shape trans configuration to crosslink two adjacent DRE sites.Impaired DUX4/IGH-mediated crosslinking abolishes ERGalt,CLEC12Aalt,and C6orf89alt biogenesis,resulting in marked alleviation of its inhibitory effect on B-cell differentiation.Furthermore,we also observed a rare RAG1/2-mediated recombination signal sequence-like DNA edition in DUX4/IGH target genes.Supportively,shRNA knock-down of RAG1/2 in leukemic Reh cells consistently impaired the biogenesis of ERGalt,CLEC12Aalt,and C6orf89alt.Conclusions:All these results suggest that DUX4/IGH-driven DNA crosslinking is required for RAG1/2 recruitment onto the double tandem DRE-DRE sites,catalyzing V(D)J-like recombination and oncogenic splicing in acute lymphoblastic leukemia.
