title: The stability of human beta-globin mRNA is dependent on structural determinants positioned within its 3' untranslated region.
abstract: Controls that act at both transcriptional and posttranscriptional levels assure that globin genes are highly expressed in developing erythroid cells. The extraordinary stabilities of alpha- and beta-globin mRNAs permit globin proteins to accumulate to substantial levels in these cells, even in the face of physiologic transcriptional silencing. Structural features that determine alpha-globin mRNA stability have recently been identified within its 3'UTR; in contrast, the structural features that determine beta-globin mRNA stability remain obscure. The current study begins to define the structural basis for beta-globin mRNA stability. Two tandem antitermination mutations are introduced into the wild-type human beta-globin gene that permit ribosomes to read into the 3'UTR of the encoded beta-globin mRNA. The readthrough beta-globin mRNA is destabilized in cultured erythroid cells, indicating that, as in human alpha-globin mRNA, an unperturbed 3'UTR is crucial to maintaining mRNA stability. Additional experiments show that the beta-globin and alpha-globin mRNA 3'UTRs provide equivalent levels of stability to a linked beta-globin mRNA coding region, suggesting a parallel in their functions. However, destabilization of the antiterminated beta-globin mRNA is independent of active translation into the 3'UTR, whereas translation into the alpha-globin mRNA 3'UTR destabilizes a linked beta-globin coding region in a translationally dependent manner. This indicates that the alpha- and beta-globin 3'UTRs may stabilize linked mRNAs through distinct mechanisms. Finally, it is shown that neither of the two mutations that, in combination, destabilize the beta-globin mRNA have any effect on beta-globin mRNA stability when present singly, suggesting potential redundancy of stabilizing elements. In sum, the current study shows that a functionally intact beta-globin mRNA 3'UTR is crucial to maintaining beta-globin mRNA stability and provides a level of stability that is functionally equivalent to, although potentially mechanistically distinct from, the previously characterized alpha-globin mRNA 3'UTR stability element.
authors.affiliation: Howard Hughes Medical Institute, University of Pennsylvania, Philadelphia, PA, USA.
authors.forename: J E
authors.initials: JE
authors.lastname: Russell
authors.forename: S A
authors.initials: SA
authors.lastname: Liebhaber
mesh_terms: D000818:Animals; D001483:Base Sequence; D015672:Erythroid Precursor Cells / Q000378:metabolism*; D015973:Gene Expression Regulation, Leukemic; D005914:Globins / Q000235:genetics*; D006207:Half-Life; D006801:Humans; D004915:Leukemia, Erythroblastic, Acute / Q000473:pathology; D051379:Mice; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009690:Nucleic Acid Conformation; D016133:Polymerase Chain Reaction; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics; D012270:Ribosomes / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured
chemical_list: D012333:RNA, Messenger; D011994:Recombinant Proteins; D005914:Globins