Translational effects and coding potential of an upstream open reading frame associated with DOPA Responsive Dystonia

Abstract

Upstream open reading frames (uORFs) have emerged as major post-transcriptional regulatory elements in eukaryotic species. In general, uORFs are initiated by a translation start codon within the 5' untranslated region of a gene (upstream ATG; uATG), and they are negatively correlated with translational efficiency. In addition to their translational regulatory role, some uORFs can code for biologically active short peptides. The importance of uATGs/uORFs is further underscored by human diseases associated with single nucleotide polymorphisms (SNPs), which disrupt existing uORFs or introduce novel uORFs. Although several functional proteins translated from naturally occurring uORFs have been described, the coding potential of uORFs created by SNPs has been ignored because of the a priori assumption that these proteins are short-lived with no likely impact on protein homeostasis. Thus, studies on SNP-created uORFs are limited to their translational effects, leaving unexplored the potential cellular consequences of a SNP/uORF-encoded protein. Here, we investigate functionality of a uATG/uORF introduced by a +142C>T SNP within the GCH1 gene and associated with a familial form of DOPA Responsive Dystonia. We report that the +142C>T SNP represses GCH1 translation, and introduces a short, frame shifted uORF that encodes a 73-amino acid peptide. This peptide is localized within the nucleus and compromises cell viability upon proteasome inhibition. Our work extends the list of uATG/uORF associated diseases and advances research on peptides translated from SNP-introduced uORFs, a neglected component of the proteome.

A novel rare c.-39C>T mutation in the PROS1 5′UTR causing PS deficiency by creating a new upstream translation initiation codon

“…Even if the flanking sequence of the new ATG does not completely match the consensus predicted Kozak sequence ((G/A)NNAUGG), it seems similar to the one flanking the natural PROS1 ATG, suggesting that the new ATG could be identified by the translational machinery and thus used in the cells [30,31]. Several works have previously demonstrated that uAUG and uORF are cis-regulatory elements in 5 UTR that are able to control protein expression by altering the translation efficiency and could subsequently be associated with risk of diseases [32][33][34][35]. Many previously ignored uORFs are now known to act as major post-transcriptional regulatory elements or to be translated to produce bioactive peptides or proteins [36,37].…”

“…Several works have previously demonstrated that uAUG and uORF are cis-regulatory elements in 5 UTR that are able to control protein expression by altering the translation efficiency and could subsequently be associated with risk of diseases [32][33][34][35]. Many previously ignored uORFs are now known to act as major post-transcriptional regulatory elements or to be translated to produce bioactive peptides or proteins [36,37].…”

A novel rare c. -39C>T mutation in thePROS15’UTR causing PS deficiency by creating a new upstream translation initiation codon and inhibiting the production of the natural protein

“…Several works have previously demonstrated that uAUG and uORF are cis-regulatory elements in 5‘UTR that are able to control protein expression by altering the translation efficiency and could subsequently be associated with risk of diseases (Dvir et al ., 2013; Lin et al ., 2019; Orr et al ., 2019; von Bohlen et al ., 2017). Many previously ignored uORFs are now known to act as major post-transcriptional regulatory elements or to be translated to produce bioactive peptides or proteins (Jones et al , 2017; Orr et al , 2019).…”

Gene expression regulation by upstream open reading frames in rare diseases

“…Several examples of deregulated uORFs associated with the onset or development of rare diseases were well reviewed by Barbosa and co-workers 1 . Meanwhile, other cases have been described (Table 1), highlighting and reinforcing the impact of uORFs in mediating translational regulation in human health and disease [56][57][58][59][60][61] .…”

“…Other examples of rare diseases that can be related to the creation of uORFs include familial DOPA responsive dystonia (DRD) and acampomelic campomelic dysplasia (ACD) 56,59 . In the first case the polymorphism c.-22C>T in the 5'UTR of the human guanosine triphosphate cyclohydrolase 1 (GCH1) gene creates an out-of-frame uORF that encodes a 73-amino acid peptide, impairing the main ORF translation 56,57 . The subsequent low expression of GCH1 impairs the dopamine biosynthesis pathway that, ultimately, results in reduced levels of dopamine and dopaminergic dysfunction in the brain, typical of DRD.…”