Zebrafish MiR-430 Promotes Deadenylation and Clearance of Maternal mRNAs

Abstract

MicroRNAs (miRNAs) comprise 1 to 3% of all vertebrate genes, but their in vivo functions and mechanisms of action remain largely unknown. Zebrafish miR-430 is expressed at the onset of zygotic transcription and regulates morphogenesis during early development. By using a microarray approach and in vivo target validation, we find that miR-430 directly regulates several hundred target messenger RNA molecules (mRNAs). Most targets are maternally expressed mRNAs that accumulate in the absence of miR-430. We also show that miR-430 accelerates the deadenylation of target mRNAs. These results suggest that miR-430 facilitates the deadenylation and clearance of maternal mRNAs during early embryogenesis.

MiRNA expression analysis during normal zebrafish development and following inhibition of the Hedgehog and Notch signaling pathways

“…Such changes are indicated by an increase in red color as development proceeds. This agrees with the hypothesis that miRNAs play an important role in differentiation and development (Chen et al, 2005;Wienholds et al, 2005;Giraldez et al, 2006;Naguibneva et al, 2006;Schratt et al, 2006;Voorhoeve et al, 2006). The one notable exception to relatively limited expression of miRNAs during early development is the pattern observed at sphere stage embryos where there appears to be significantly greater expression compared to other early time points (Fig.…”

The knockdown of maternal glucocorticoid receptor mRNA alters embryo development in zebrafish

“…This is responsible for the degradation by Dicer activity of hundreds of RNAs that bear miR-430-binding sites in their 3 0 UTR, as is the case of many maternal mRNAs. miRNAs in general have been implicated in the degradation of 750 transcripts after MBT, as determined by microarray analysis (Giraldez et al, 2006). Due to differences in microarray technology, the above transcripts are not entirely comparable with the 778 transcripts, presumably mainly maternal, found to be altered at 5 hpf in gr ATG1 MO embryos.…”

Transitioning from egg to embryo: Triggers and mechanisms of egg activation

“…Upon activation nanos mRNA is degraded everywhere except the posterior pole of the oocyte, where it is translated and functions in posterior patterning (Bashirullah et al, 1999;Bergsten and Gavis, 1999). Degradation can also remove mRNAs whose products are no longer needed or that interfere with later development, such as during the maternal to zygotic transition (MZT; mammals, zebrafish) or mid-blastula transition (MBT; Xenopus, Drosophila) (Bashirullah et al, 1999;Hamatani et al, 2004;Giraldez et al, 2006;Tadros et al, 2007).…”

“…While this mechanism requires zygotic transcription and is thus not triggered by activation, it is responsible for the degradation of a large proportion of maternal mRNAs. A microRNA, miR-430, is transcribed at the MZT and binds to complementary sites in the 3ЈUTR of several hundred maternal mRNAs, promoting their deadenylation (Giraldez et al, 2006). When miR-430 is not present, maternal transcripts accumulate and interfere with embryonic morphogenesis (Giraldez et al, 2006).…”