title: Identification of 3'UTR sequence elements and a teloplasm localization motif sufficient for the localization of Hro-twist mRNA to the zygotic animal and vegetal poles.
abstract: The early localization of mRNA transcripts is critical in sorting cell fate determinants in the developing embryo. In the glossiphoniid leech, Helobdella robusta, maternal mRNAs, such as Hro-twist, localize to the zygotic teloplasm. Ten seven nucleotide repeat elements (AAUAAUA) called ARE2 and a predicted secondary structural motif, called teloplasm localization motif (TLM), are present in the 3'UTR of Hro-twist mRNA. We used site-directed mutagenesis, deletions, and microinjection of labeled, exogenous transcripts to determine if ARE2 elements, and the TLM, play a role in Hro-twist mRNA localization. Deleting the poly-A tail and the cytoplasmic polyadenylation element (CPE) had no effect on Hro-twist mRNA localization. Site-directed mutagenesis of nucleotides that altered ARE2 element sequences or the TLM suggest that the ARE2 elements and the TLM are important for Hro-twist mRNA localization to the teloplasm of pre-cleavage zygotes. Hro-Twist protein expression data suggest that the localization of Hro-twist transcripts in zygotes and stage two embryos is not involved in ensuring mesoderm specification, as Hro-Twist protein is expressed uniformly in most cells before gastrulation. Our data may support a shared molecular mechanism for leech transcripts that localize to the teloplasm.
authors.affiliation: Biological Sciences Department, San Jose State University, San Jose, CA 95192-0100, USA.
authors.forename: Mehrin
authors.initials: M
authors.lastname: Farooq
authors.forename: Jonathan
authors.initials: J
authors.lastname: Choi
authors.forename: Agustin I
authors.initials: AI
authors.lastname: Seoane
authors.forename: Roberto A
authors.initials: RA
authors.lastname: Lleras
authors.forename: Hoan V
authors.initials: HV
authors.lastname: Tran
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Mandal
authors.forename: Christine L
authors.initials: CL
authors.lastname: Nelson
authors.forename: Julio G
authors.initials: JG
authors.lastname: Soto
mesh_terms: D020413:3' Untranslated Regions; D000818:Animals; D019521:Body Patterning; D003001:Cloning, Molecular; D019295:Computational Biology; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000196:embryology; D047108:Embryonic Development; D018507:Gene Expression Regulation, Developmental; D007865:Leeches / Q000196:embryology / Q000235:genetics*; D008648:Mesoderm / Q000166:cytology / Q000196:embryology; D016297:Mutagenesis, Site-Directed; D059372:Nucleotide Motifs; D017354:Point Mutation; D017433:Protein Structure, Secondary; D059370:RNA Folding; D034443:RNA Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012091:Repetitive Sequences, Nucleic Acid; D051879:Twist-Related Protein 1 / Q000235:genetics / Q000378:metabolism*; D015053:Zygote / Q000166:cytology / Q000378:metabolism*
chemical_list: D020413:3' Untranslated Regions; D012333:RNA, Messenger; D051879:Twist-Related Protein 1