Abstract
BackgroundDuring zebrafish embryogenesis, microRNA (miRNA) miR-430 contributes to restrict Nanos1 and TDRD7 to primordial germ cells (PGCs) by inducing mRNA deadenylation, mRNA degradation, and translational repression of nanos1 and tdrd7 mRNAs in somatic cells. The nanos1 and tdrd7 3′UTRs include cis-acting elements that allow activity in PGCs even in the presence of miRNA-mediated repression.Methodology/Principal FindingsUsing a GFP reporter mRNA that was fused with tdrd7 3′UTR, we show that a germline-specific RNA-binding protein DAZ-like (DAZL) can relieve the miR-430-mediated repression of tdrd7 mRNA by inducing poly(A) tail elongation (polyadenylation) in zebrafish. We also show that DAZL enhances protein synthesis via the 3′UTR of dazl mRNA, another germline mRNA targeted by miR-430.Conclusions/SignificanceOur present study indicated that DAZL acts as an “anti-miRNA factor” during vertebrate germ cell development. Our data also suggested that miRNA-mediated regulation can be modulated on specific target mRNAs through the poly(A) tail control.
Highlights
Post-transcrptional regulation plays a crucial role in germ cell development
It has been shown that vasa, nanos1, and tdrd7 mRNAs are rapidly degraded in somatic cells but are stabilized in primordial germ cells (PGCs) in a process mediated by cis-acting elements in their 39 untranslated regions (39 UTRs) [3,5,6,7]
Our previous study showed that microRNA miR-430, which is abundantly expressed from the onset of zygotic gene expression [8], targets the 39UTRs of nanos1 and tdrd7 to induce mRNA deadenylation, mRNA degradation, and translational repression in somatic cells [5]
Summary
Post-transcrptional regulation plays a crucial role in germ cell development. In zebrafish, primordial germ cells (PGCs) are determined by the incorporation of a specific maternal cytoplasm called germ plasm, which forms at the ends of cleavage planes in four-cell stage embryos [1,2]. A fraction of germ plasm mRNAs is detected throughout the blastomeres during cleavage stages Such unlocalized mRNAs are subsequently incorporated into somatic cells as well as PGCs. It has been shown that vasa, nanos, and tdrd mRNAs are rapidly degraded in somatic cells but are stabilized in PGCs in a process mediated by cis-acting elements in their 39 untranslated regions (39 UTRs) [3,5,6,7]. MiR-430mediated repression and the activation of germ plasm mRNAs play important roles in germline/somatic cell distinctions in zebrafish embryos. MicroRNA (miRNA) miR-430 contributes to restrict Nanos and TDRD7 to primordial germ cells (PGCs) by inducing mRNA deadenylation, mRNA degradation, and translational repression of nanos and tdrd mRNAs in somatic cells. The nanos and tdrd7 39UTRs include cis-acting elements that allow activity in PGCs even in the presence of miRNA-mediated repression
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