title: Alternative splicing and nonsense-mediated mRNA decay regulate mammalian ribosomal gene expression.
abstract: Messenger RNAs containing premature stop codons are generally targeted for degradation through nonsense-mediated mRNA decay (NMD). This mechanism degrades aberrant transcripts derived from mutant genes containing nonsense or frameshift mutations. Wild-type genes also give rise to transcripts targeted by NMD. For example, some wild-type genes give rise to alternatively spliced transcripts that are targeted for decay by NMD. In Caenorhabditis elegans, the ribosomal protein (rp) L12 gene generates a nonsense codon-bearing alternatively spliced transcript that is induced in an autoregulatory manner by the rpL12 protein. By pharmacologically blocking the NMD pathway, we identified alternatively spliced mRNA transcripts derived from the human rpL3 and rpL12 genes that are natural targets of NMD. The deduced protein sequence of these alternatively spliced transcripts suggests that they are unlikely to encode functional ribosomal proteins. Overexpression of rpL3 increased the level of the alternatively spliced rpL3 mRNA and decreased the normally expressed rpL3. This indicates that rpL3 regulates its own production by a negative feedback loop and suggests the possibility that NMD participates in this regulatory loop by degrading the non-functional alternatively spliced transcript.
authors.affiliation: Dipartimento di Biochimica e Biotecnologie Mediche, Università Federico II, via Sergio Pansini 5, Napoli 80131, Italy.
authors.forename: Monica
authors.initials: M
authors.lastname: Cuccurese
authors.forename: Giulia
authors.initials: G
authors.lastname: Russo
authors.forename: Annapina
authors.initials: A
authors.lastname: Russo
authors.forename: Concetta
authors.initials: C
authors.lastname: Pietropaolo
mesh_terms: D017398:Alternative Splicing; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D045744:Cell Line, Tumor; D018389:Codon, Nonsense; D006801:Humans; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D000090822:Ribosomal Protein L3; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D018389:Codon, Nonsense; D012333:RNA, Messenger; C000716547:RPL3 protein, human; D000090822:Ribosomal Protein L3; D012269:Ribosomal Proteins; C000716548:Rpl3 protein, mouse; C000716549:Rpl3 protein, rat; C016700:ribosomal protein L7-L12