| First Author | Cadar AG | Year | 2014 |
| Journal | Biochem Biophys Res Commun | Volume | 453 |
| Issue | 1 | Pages | 185-91 |
| PubMed ID | 25264194 | Mgi Jnum | J:220077 |
| Mgi Id | MGI:5632214 | Doi | 10.1016/j.bbrc.2014.09.085 |
| Citation | Cadar AG, et al. (2014) Upstream open reading frame in 5'-untranslated region reduces titin mRNA translational efficiency. Biochem Biophys Res Commun 453(1):185-91 |
| abstractText | Titin is the largest known protein and a critical determinant of myofibril elasticity and sarcomere structure in striated muscle. Accumulating evidence that mRNA transcripts are post-transcriptionally regulated by specific motifs located in the flanking untranslated regions (UTRs) led us to consider the role of titin 5'-UTR in regulating its translational efficiency. Titin 5'-UTR is highly homologous between human, mouse, and rat, and sequence analysis revealed the presence of a stem-loop and two upstream AUG codons (uAUGs) converging on a shared in frame stop codon. We generated a mouse titin 5'-UTR luciferase reporter construct and targeted the stem-loop and each uAUG for mutation. The wild-type and mutated constructs were transfected into the cardiac HL-1 cell line and primary neonatal rat ventricular myocytes (NRVM). SV40 driven 5'-UTR luciferase activity was significantly suppressed by wild-type titin 5'-UTR ( approximately 70% in HL-1 cells and approximately 60% in NRVM). Mutating both uAUGs was found to alleviate titin 5'-UTR suppression, while eliminating the stem-loop had no effect. Treatment with various growth stimuli: pacing, PMA or neuregulin had no effect on titin 5'-UTR luciferase activity. Doxorubicin stress stimuli reduced titin 5'-UTR suppression, while H2O2 had no effect. A reported single nucleotide polymorphism (SNP) rs13422986 at position -4 of the uAUG2 was introduced and found to further repress titin 5'-UTR luciferase activity. We conclude that the uAUG motifs in titin 5'-UTR serve as translational repressors in the control of titin gene expression, and that mutations/SNPs of the uAUGs or doxorubicin stress could alter titin translational efficiency. |
