An internal ribosome entry site mediates the initiation of soluble guanylyl cyclase beta2 mRNA translation.
The soluble guanylyl cyclases (sGC), the receptor for nitric oxide, are heterodimers consisting of an alpha- and beta-subunit. This study aimed to investigate the translational mechanism of the sGC beta2-subunit. Two mRNA species for sGC beta2 were isolated from human kidney. These transcripts had dissimilar 5'-untranslated regions (5'-UTRs). The most abundant sGC beta2 mRNA showed numerous upstream open reading frames (ORFs) and stable secondary structures that inhibited in vivo and in vitro translation. To evaluate whether these 5'-UTRs harbored an internal ribosome entry site (IRES) that allows translation by an alternative mechanism, we inserted these regions between the two luciferase genes of a bicistronic vector. Transfection of those genetic constructs into HeLa cells demonstrated that both sGC beta2 leaders had IRES activity in a cell-type dependent manner. Finally, the secondary structural model of the sGC beta2 5'-UTR predicts a Y-type pseudoknot that characterizes the IRES of cellular mRNAs. In conclusion, our findings suggest that sGC beta2 5'-UTRs have IRES activity that may permit sGC beta2 expression under conditions that are not optimal for scanning-dependent translation.
University of Miami Miller School of Medicine, Miami, FL 33136, USA. rvazquez@med.miami.edu
Roberto I
RI
Vazquez-Padron
Si M
SM
Pham
Dania
D
Mateu
Sheik
S
Khan
Abdelouahab
A
Aitouche
D020121:5' Untranslated Regions / Q000737:chemistry* / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D003001:Cloning, Molecular; D017930:Genes, Reporter; D006162:Guanylate Cyclase / Q000096:biosynthesis / Q000235:genetics*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010442:Peptide Chain Initiation, Translational; D011401:Promoter Regions, Genetic; D022821:RNA Splice Sites; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis / Q000235:genetics*; D000071756:Soluble Guanylyl Cyclase; D014158:Transcription, Genetic
D020121:5' Untranslated Regions; D022821:RNA Splice Sites; D018160:Receptors, Cytoplasmic and Nuclear; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase