Regulation of neuronal gene expression is critical to nervous system development. REST (RE1-silencing transcription factor) regulates neuronal gene expression through interacting with a group of corepressor proteins including REST corepressor (RCOR). Here we show that Xenopus RCOR2 is predominantly expressed in the developing nervous system. Through a yeast two-hybrid screen, we isolated XenopusZMYND8 (Zinc finger and MYND domain containing 8) as an XRCOR2 interacting factor. XRCOR2 and XZMYND8 bind each other in co-immunoprecipitation assays and both of them can function as transcriptional repressors. XZMYND8 is co-expressed with XRCOR2 in the nervous system and overexpression of XZMYND8 inhibits neural differentiation in Xenopus embryos. These data reveal a RCOR2/ZMYND8 complex which might be involved in the regulation of neural differentiation. The BRUNOL/CELF family of RNA-binding proteins plays important roles in post-transcriptional regulation and has been implicated in several developmental processes. Previous studies show that BRUNOL1 is expressed specifically in the nervous system, inhibiting its function leads to defects in the brain, eyes, and body axes . Overexpression of BRUNOL1 also leads to brain malformation. But its target RNA is unkown. The wild type BRUNOL1 protein is localized both in the cytoplasm and nucleus. To clarify whether it functions in the cytoplasm or the nucleus, we constructed a fusion of BRUNOL1 and glucocorticoid reccptor (GR) whose subcellular localization can be regulated by dexamethasone and overexpressed it to Xenopus embryos. In the absence of dexamethasone, the fusion is restricted in the cytoplasm and the embryos develop normally, while in the presence of dexamethasone, it is translocated into the nucleus, and the embryos are brain malformation. This result suggests BRUNOL1 is functional in the nucleus for nervous system development. As an RNA binding protein, it could be involved in RNA splicing or editing of its target RNAs in the nucleus. To screen for its target genes, we carried out a microarray analysis to compare the RNA expression profile of embryos injected with BRUNOL1 mRNA, morpholino and control embryos.
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