Identification of 3′ UTR sequence elements and a teloplasm localization motif sufficient for the localization of Hro‐twist m RNA to the zygotic animal and vegetal poles

• Published in: Development, growth & differentiation Vol. 54; no. 4; pp. 519 - 534
• Main Authors: Farooq, Mehrin, Choi, Jonathan, Seoane, Agustin I., Lleras, Roberto A., Tran, Hoan V., Mandal, Stephanie A., Nelson, Christine L., Soto, Julio G.
• Format: Journal Article
• Language: English
• Published: 01.05.2012
• ISSN: 0012-1592; 1440-169X
• DOI: 10.1111/j.1440-169X.2012.01352.x

The early localization of m RNA transcripts is critical in sorting cell fate determinants in the developing embryo. In the glossiphoniid leech, H elobdella robusta , maternal m RNA s, 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 m RNA . 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 m RNA localization. Deleting the poly‐A tail and the cytoplasmic polyadenylation element ( CPE ) had no effect on Hro‐twist m RNA 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 m RNA 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.