title: JKTBP1 is involved in stabilization and IRES-dependent translation of NRF mRNAs by binding to 5' and 3' untranslated regions.
abstract: Heterogeneous nuclear ribonucleoprotein D-like protein (JKTBP) 1 was implicated in cap-independent translation by binding to the internal ribosome entry site in the 5' untranslated region (UTR) of NF-κB-repressing factor (NRF). Two different NRF mRNAs have been identified so far, both sharing the common 5' internal ribosome entry site but having different length of 3' UTRs. Here, we used a series of DNA and RNA luciferase reporter constructs comprising 5', 3' or both NRF UTRs to study the effect of JKTBP1 on translation of NRF mRNA variants. The results indicate that JKTBP1 regulates the level of NRF protein expression by binding to both NRF 5' and 3' UTRs. Using successive deletion and point mutations as well as RNA binding studies, we define two distinct JKTBP1 binding elements in NRF 5' and 3' UTRs. Furthermore, JKTBP1 requires two distinct RNA binding domains to interact with NRF UTRs and a short C-terminal region for its effect on NRF expression. Together, our study shows that JKTBP1 contributes to NRF protein expression via two disparate mechanisms: mRNA stabilization and cap-independent translation. By binding to 5' UTR, JKTBP1 increases the internal translation initiation in both NRF mRNA variants, whereas its binding to 3' UTR elevated primarily the stability of the major NRF mRNA. Thus, JKTBP1 is a key regulatory factor linking two pivotal control mechanisms of NRF gene expression: the cap-independent translation initiation and mRNA stabilization.
authors.affiliation: Institute of Pharmacology, Hannover Medical School, 30625 Hannover, Germany.
authors.forename: Deike Johanne
authors.initials: DJ
authors.lastname: Omnus
authors.forename: Sarah
authors.initials: S
authors.lastname: Mehrtens
authors.forename: Birgit
authors.initials: B
authors.lastname: Ritter
authors.forename: Klaus
authors.initials: K
authors.lastname: Resch
authors.forename: Michiyuki
authors.initials: M
authors.lastname: Yamada
authors.forename: Ronald
authors.initials: R
authors.lastname: Frank
authors.forename: Mahtab
authors.initials: M
authors.lastname: Nourbakhsh
authors.forename: Marc René
authors.initials: MR
authors.lastname: Reboll
mesh_terms: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D019677:Artificial Gene Fusion; D017930:Genes, Reporter; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D017354:Point Mutation; D011485:Protein Binding; D014176:Protein Biosynthesis; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D012097:Repressor Proteins / Q000096:biosynthesis*; D012261:Ribonucleoproteins / Q000378:metabolism*; D017384:Sequence Deletion
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; C111986:HNRPDL protein, human; C111027:NKRF protein, human; D012333:RNA, Messenger; D016601:RNA-Binding Proteins; D012097:Repressor Proteins; D012261:Ribonucleoproteins; D008156:Luciferases