Involvement of SR proteins in mRNA surveillance.
Nonsense mutations influence several aspects of gene expression, including mRNA stability and splicing fidelity, but the mechanism by which premature termination codons (PTCs) can apparently affect splice-site selection remains elusive. We used a model human beta-globin gene with duplicated 5' splice sites (5'ss) and found that PTCs inserted between the two 5'ss do not directly influence splicing in this system. Instead, their apparent effect on 5'ss selection in vivo is an indirect result of nonsense-mediated mRNA decay (NMD), as conditions that eliminated NMD also abrogated the effect on splicing. Remarkably, we found an unexpected function of SR proteins in targeting several mRNAs with PTCs to the NMD pathway. Overexpression of various SR proteins strongly enhanced NMD, and this effect required an RS domain. Our data argue against a universal role of PTCs in regulating pre-mRNA splicing and reveal an additional function of SR proteins in eukaryotic gene expression.
Zhang
Zuo
Z
Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
Krainer
Adrian R
AR
D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002522:Chlorocebus aethiops; D018389:Codon, Nonsense; D018388:Codon, Terminator; D005091:Exons; D005786:Gene Expression Regulation; D005914:Globins / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism*; D017354:Point Mutation; D034622:RNA Interference; D012322:RNA Precursors / Q000378:metabolism; D012326:RNA Splicing; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors
D018389:Codon, Nonsense; D018388:Codon, Terminator; D009687:Nuclear Proteins; D012322:RNA Precursors; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D000068103:Serine-Arginine Splicing Factors; D005914:Globins