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Human RNPS1 protein was first identified as a pre-mRNA splicing activator in vitro and RNPS1 regulates alternative splicing in cellulo . RNPS1 was also known as a peripheral factor of the exon junction complex (EJC). Here we show that cellular knockdown of RNPS1 induced a reduction of the wild-type aurora kinase B (AURKB) protein due to the induced aberrant pre-mRNA splicing events, indicating that the fidelity of AURKB pre-mRNA splicing was reduced. The major aberrant AURKB mRNA was derived from the upstream pseudo 5′ and 3′ splice sites in intron 5, which resulted in the production of the non-functional truncated AURKB protein. AURKB, is an essential mitotic factor, whose absence is known to cause multiple nuclei, and this multinucleation phenotype was recapitulated in RNPS1-knockdown cells. Importantly this RNPS1-knockdown phenotype was rescued by ectopic expression of AURKB, implying it is a major functional target of RNPS1. We found RNPS1 protein, not as a component of the EJC, binds directly to a specific element in the AURKB exon upstream of the authentic 5′ splice site, and this binding is required for normal splicing. RNPS1-knockdown induces a parallel aberrant splicing pattern in a fully distinct pre-mRNA, MDM2, suggesting that RNPS1 is a global guardian of splicing fidelity. We conclude that RNPS1 is a key factor for the quality control of mRNAs that is essential for the phenotypes including cell division. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRs) are a group of small RNAs that play a major role in post-transcriptional regulation of gene expression. In animals, many of the miRs are expressed in a conserved spatiotemporal manner. Muscle tissues, the major cellular systems involved in the locomotion and physiological functions of animals, have been one of the main sites for verification of miR targets and analysis of their developmental functions. During the determination and differentiation of muscle cells, numerous miRs bind to and repress target mRNAs in a highly specific but redundant manner. Interspecific comparisons of the sequences and expression of miRs have suggested that miR regulation became increasingly important during the course of vertebrate evolution. However, the detailed molecular interactions that have led to the highly complex morphological structures still await investigation. In this review, we will summarize the recent findings on the functional and developmental characteristics of miRs that have played major roles in vertebrate myogenesis, and discuss how the evolution of miRs is related to the morphological complexity of the vertebrates. [ABSTRACT FROM AUTHOR]

The cardiac neural crest is a subpopulation of cells arising from the caudal hindbrain. The delaminated cardiac neural crest cells migrate to the heart using the CXCR/SDF1 chemokine signaling system. These cells contribute to the formation of the cardiovascular system, including the septation of the outflow tract, which is unique to these cells. Here, we investigated the effect of ectopic expression of the cardiac neural crest gene MafB on trunk neural crest cells. First, we found that MafB has the potential to activate its own cis-regulatory element in enteric and trunk neural crest cells but not in cranial neural crest cells. Forced expression of two cardiac neural crest genes, Ets1 and Sox8 , together with or without MafB , induced ectopic Sox10E2 enhancer activity in the trunk region. Finally, we uncovered that the expression of MafB, Ets1 and Sox8 can induce ectopic CXCR4 expression in the trunk neural crest cells, resulting in acquisition of responsiveness to the SDF1 signal. These results demonstrate that MafB, Ets1 and Sox8 are critical components for generation of the identity of the cardiac neural crest, especially the cell migration property. [Display omitted] • MafB activates MafB E1 reporter expression in enteric and trunk neural crests. • CXCR4 is ectopically induced by MafB, Ets1 and Sox8 in trunk neural crest cells. • MafB, Ets1 and Sox8 establish the cell migration property of cardiac neural crest. [ABSTRACT FROM AUTHOR]

Abstract The cardiac neural crest originates in the caudal hindbrain, migrates to the heart, and contributes to septation of the cardiac outflow tract and ventricles, an ability unique to this neural crest subpopulation. Here we have used a FoxD3 neural crest enhancer to isolate a pure population of cardiac neural crest cells for transcriptome analysis. This has led to the identification of transcription factors, signaling receptors/ligands, and cell adhesion molecules upregulated in the early migrating cardiac neural crest. We then functionally tested the role of one of the upregulated transcription factors, MafB , and found that it acts as a regulator of Sox10 expression specifically in the cardiac neural crest. Our results not only reveal the genome-wide profile of early migrating cardiac neural crest cells, but also provide molecular insight into what makes the cardiac neural crest unique. Highlights • We describe the transcriptome of early migrating cardiac neural crest cells. • We show that the transcription factor MafB is required in migrating cardiac neural crest cells. • We characterize two biologically relevant MafB binding sites within the Sox10 enhancer Sox10E2. [ABSTRACT FROM AUTHOR]

Germline and somatic cell distinction is regulated through a combination of microRNA and germ cell-specific RNA-binding proteins in zebrafish. An RNA-binding protein, DND, has been reported to relieve the miR-430-mediated repression of some germ plasm mRNAs such as nanos3 and tdrd7 in primordial germ cells (PGCs). Here, we showed that miR-430-mediated repression is not counteracted by the overexpression of DND protein in somatic cells. Using a λN-box B tethering assay in the embryo, we found that tethering of DND to reporter mRNA results in translation repression without affecting mRNA stability. Translation repression by DND was not dependent on another germline-specific translation repressor, Nanos3, in zebrafish embryos. Moreover, our data suggested that DND represses translation of nanog and dnd mRNAs, whereas an RNA-binding protein DAZ-like (DAZL) promotes dnd mRNA translation. Thus, our study showed that DND protein functions as a translation repressor of specific mRNAs to control PGC development in zebrafish. [ABSTRACT FROM AUTHOR]

Abstract: Many studies have demonstrated the functions of individual genes associated with embryogenesis and have determined the genome sequences of several organisms. Despite the availability of enormous amount of genetic information, dynamic changes that occur during embryogenesis have not yet been completely understood. In order to understand the dynamic processes involved in embryogenesis, we employed the metabolomic approach. The results of our study indicated that there is a close correlation between metabolomes and developmental stages. Our method enables the identification of embryonic stages using metabolomes as “fingerprints.” In this manner, we could successfully predict embryonic development on the basis of metabolomic fingerprints. This is the first report describing a model for predicting vertebrate development by using metabolomics. [Copyright &y& Elsevier]

Hu proteins are RNA-binding proteins that are implicated in the control of stabilization, nuclear export, and/or translation of specific mRNAs with AU-rich elements (AREs) in the 3′-untranslated region. Three neuron-specific Hu proteins (HuD, HuB, and HuC), but not a ubiquitously expressed Hu protein HuR, have an activity to induce neurite outgrowth when they are overexpressed in a rat neuronal cell line PC12. Here we show that TAP/NXF1, the primary export receptor for the bulk mRNA, is a specific binding partner for HuD. In vitro binding experiments using recombinant proteins revealed that the interaction between TAP and HuD is direct and that HuD can form a ternary complex together with both TAP and RNA. Interestingly, HuR does not interact with TAP. These results suggest that HuD acts as a novel adaptor protein to recruit TAP for efficient export of ARE-containing mRNAs in neuronal cells. [Copyright &y& Elsevier]

Maternally supplied factors in fertilized eggs play essential roles in the establishment of primordial germ cells. In zebrafish, cytoplasm at the distal ends of the first and second cleavage furrows has been assumed to contain germ lineage determinants, since maternal transcripts of germ lineage-specific genes are localized to ends of the cleavage furrows. To investigate whether these parts of cytoplasm are required for germ cell formation, we removed all four regions of the cytoplasm by glass capillary at the 4-cell stage. Histological analysis revealed that the ablation of cytoplasm at the ends of the cleavage planes resulted in a severe reduction in the number of germ cells. In addition, the expression of germ lineage markers was eliminated by cytoplasmic ablation. These results demonstrated that cytoplasm at the distal ends of cleavage furrows is essential for germ cell formation. We also found novel localization patterns for zDazl and brul mRNAs along the cleavage planes. Our findings provide the first direct evidence that localized cytoplasmic factors are indispensable for germ cell establishment in zebrafish. [Copyright &y& Elsevier]