title: Translation initiation factor eIF3h targets specific transcripts to polysomes during embryogenesis.
abstract: Eukaryotic translation initiation factor 3 (eIF3) plays a central role in translation initiation and consists of five core (conserved) subunits present in both budding yeast and higher eukaryotes. Higher eukaryotic eIF3 contains additional (noncore or nonconserved) subunits of poorly defined function, including sub-unit h (eIF3h), which in zebrafish is encoded by two distinct genes (eif3ha and eif3hb). Previously we showed that eif3ha encodes the predominant isoform during zebrafish embryogenesis and that depletion of this factor causes defects in the development of the brain and eyes. To investigate the molecular mechanism governing this regulation, we developed a genome-wide polysome-profiling strategy using stage-matched WT and eif3ha morphant zebrafish embryos. This strategy identified a large set of predominantly neural-associated translationally regulated mRNAs. A striking finding was a cohort of lens-associated crystallin isoform mRNAs lost from the eif3ha morphant polysomes, revealing a mechanism by which lens development is translationally controlled. We show that both UTR sequences of a targeted crystallin transcript are necessary but not sufficient for translational regulation by eif3ha. Therefore, our study reveals the role of a noncore eIF3 subunit in modulating a specific developmental program by regulating translation of defined transcripts and highlights the potential of the zebrafish system to identify translational regulatory mechanisms controlling vertebrate development.
authors.affiliation: Department of Developmental and Molecular Biology, Albert Einstein College of Medicine of Yeshiva University, Bronx, NY 10461, USA.
authors.forename: Avik
authors.initials: A
authors.lastname: Choudhuri
authors.forename: Umadas
authors.initials: U
authors.lastname: Maitra
authors.forename: Todd
authors.initials: T
authors.lastname: Evans
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004625:Embryo, Nonmammalian / Q000196:embryology / Q000378:metabolism*; D039621:Eukaryotic Initiation Factor-3 / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D011132:Polyribosomes / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D015027:Zebrafish / Q000196:embryology / Q000235:genetics / Q000378:metabolism; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*; D038222:gamma-Crystallins / Q000235:genetics / Q000378:metabolism
chemical_list: D039621:Eukaryotic Initiation Factor-3; D021122:Protein Subunits; D012333:RNA, Messenger; D029961:Zebrafish Proteins; D038222:gamma-Crystallins
keywords: Crygm2d; RNA sequencing