Competency for nonsense-mediated reduction in collagen X mRNA is specified by the 3' UTR and corresponds to the position of mutations in Schmid metaphyseal chondrodysplasia.
Nonsense-mediated decay (NMD) is a eukaryotic cellular RNA surveillance and quality-control mechanism that degrades mRNA containing premature stop codons (nonsense mutations) that otherwise may exert a deleterious effect by the production of dysfunctional truncated proteins. Collagen X (COL10A1) nonsense mutations in Schmid-type metaphyseal chondrodysplasia are localized in a region toward the 3' end of the last exon (exon 3) and result in mRNA decay, in contrast to most other genes in which terminal-exon nonsense mutations are resistant to NMD. We introduce nonsense mutations into the mouse Col10a1 gene and express these in a hypertrophic-chondrocyte cell line to explore the mechanism of last-exon mRNA decay of Col10a1 and demonstrate that mRNA decay is spatially restricted to mutations occurring in a 3' region of the exon 3 coding sequence; this region corresponds to where human mutations have been described. This localization of mRNA-decay competency suggested that a downstream region, such as the 3' UTR, may play a role in specifying decay of mutant Col10a1 mRNA containing nonsense mutations. We found that deleting any of the three conserved sequence regions within the 3' UTR (region I, 23 bp; region II, 170 bp; and region III, 76 bp) prevented mutant mRNA decay, but a smaller 13 bp deletion within region III was permissive for decay. These data suggest that the 3' UTR participates in collagen X last-exon mRNA decay and that overall 3' UTR configuration, rather than specific linear-sequence motifs, may be important in specifying decay of Col10a1 mRNA containing nonsense mutations.
Tan
Jacqueline T
JT
Murdoch Childrens Research Institute, University of Melbourne, Royal Children's Hospital, Parkville, Victoria 3052, Australia.
Kremer
Friederike
F
Freddi
Susanna
S
Bell
Katrina M
KM
Baker
Naomi L
NL
Lamandé
Shireen R
SR
Bateman
John F
JF
D020413:3' Untranslated Regions / Q000378:metabolism*; D000818:Animals; D001483:Base Sequence; D018389:Codon, Nonsense; D024121:Collagen Type X / Q000235:genetics*; D005091:Exons; D006801:Humans; D051379:Mice; D008817:Mice, Mutant Strains; D010009:Osteochondrodysplasias / Q000235:genetics*; D020871:RNA Stability / Q000235:genetics*; D012333:RNA, Messenger
D020413:3' Untranslated Regions; D018389:Codon, Nonsense; D024121:Collagen Type X; D012333:RNA, Messenger