Msi is expressed in neural tissues in both the central nervous system (CNS) and PNS ( Okano et al., 2002 and Okano et al., 2005). Members of the Msi family include Drosophila Msi, and ascidian MUSASHI from Halocynthia roretzi and Ciona intestinalis ( Kawashima et al., 2000) in invertebrates. Vertebrate Msi family members include the frog (Xenopus laevis) nervous system-specific RNP protein-1 (Nrp-1) ( Richter et al., 1990 and Sharma Ixazomib mouse and Cline, 2010), torafugu (Fugu rubripes) Msi-1 ( Aparicio et al., 2002), chicken (Gallus gallus) Msi1 ( Asai et al., 2005 and Wilson

et al., 2007), mouse (Mus musculus) Msi1 ( Sakakibara et al., 1996), and human (Homo sapiens) MSI1 ( Good et al., 1998). The mouse Musashi2 (Msi2) exhibits high similarity to Msi1 in primary structure, RNA-binding specificity and CNS expression pattern. Msi2 acts cooperatively with Msi1 in the proliferation and maintenance

of NS/PCs (Sakakibara et al., 2001). Human MSI2 was identified during the course of research examining disease progression in chronic myeloid leukemia (Barbouti et al., 2003, Ito et al., 2010 and Kharas et al., 2010). Among Msi family 5-FU mw members, mouse Msi1 is highly enriched in developing NS/PCs (Sakakibara et al., 1996) and is thought to contribute to the maintenance of the NS/PCs by regulating the translation of particular downstream target genes (Imai et al., 2001 and Sakakibara et al., 2002), such that Msi1 competes with eIF4G for binding to PABP, both of which are general translation factors (Kawahara et al., 2008). In this study, we report the sequence and characterize the function of the zebrafish (Danio rerio) Msi family member. One experiment essential for revealing the function of a protein is a loss-of-function study using an animal model. However, the postnatal survival rate of msi1 knockout mice is very low and determination of the adult

phenotype has not been possible. Thus, we used zebrafish as a new animal model for this Msi analysis because of Cyclin-dependent kinase 3 their transparent body, which enables detailed observations of development. Furthermore, manipulation of zebrafish, for example, by zmsi1 knock down (KD) by morpholino oligonucleotides (MOs), is relatively easy compared to mice. This zebrafish model will be an excellent tool with which to study the in vivo functions of Msi. Our present results illustrate the use of this animal model to reveal the roles of zebrafish Msi1 (zMsi1) in CNS development and its potential use as a neurological disease model. The database of zebrafish cDNA sequences contains several fragmented and incomplete sequences of Msi1. Full-length cloning primers were designed using the deposited sequences. To clone zebrafish Msi1, RT-PCR was performed using total RNA obtained from the brain of 5-week-old wild-type zebrafish (RIKEN WT), and identified a 2.3-kb cDNA clone that contained the putative full-length coding sequence of zMsi1.