Identification of a rapid mammalian deadenylation-dependent decay pathway and its inhibition by a viral RNA element.
Cellular RNAs are subject to quality-control pathways that insure the fidelity of gene expression. We previously identified a 79 nt element, the ENE, that is essential for the nuclear accumulation of a viral polyadenylated nuclear (PAN) RNA. Here, we show that intron-less polyadenylated transcripts such as PAN RNA and beta-globin cRNA exhibit two-component exponential decay kinetics in which some transcripts are rapidly degraded (t(1/2) = approximately 15 min) while others decay more slowly (t(1/2) = approximately 3 hr). Inclusion of the ENE protects such transcripts from rapid decay in a poly(A)-dependent fashion. The ENE inhibits deadenylation and decay in nuclear extract and prevents deadenylation of naked RNA by a purified deadenylase, likely through snoRNA-like intramolecular hybridization with the poly(A) tail. The ENE causes increased accumulation of splicing-defective beta-globin pre-mRNAs in vivo. We propose that the ENE-controlled rapid-decay mechanism for polyadenylated transcripts comprises a nuclear pre-mRNA surveillance system in mammalian cells.
Conrad
Nicholas K
NK
Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06536, USA.
Mili
Stavroula
S
Marshall
Eleanor L
EL
Shu
Mei-Di
MD
Steitz
Joan A
JA
D001483:Base Sequence; D004602:Elements; D005914:Globins / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D026723:Polyadenylation; D022821:RNA Splice Sites; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics*; D012367:RNA, Viral / Q000378:metabolism*; D015398:Signal Transduction; D014158:Transcription, Genetic
D004602:Elements; D022821:RNA Splice Sites; D012333:RNA, Messenger; D012367:RNA, Viral; D005914:Globins