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Yuji Kageyama

Publications and source records attributed to Yuji Kageyama.

7 recordsLinked to original sources
PubMed2006

Rapid construction of Drosophila RNAi transgenes using pRISE, a P-element-mediated transformation vector exploiting an in vitro recombination system.

RNAi is a gene-silencing phenomenon mediated by double-stranded RNA (dsRNA) and has become a powerful tool to elucidate gene function. To accomplish rapid construction of transgenes expressing dsRNA in Drosophila, we developed a novel transformation vector, pRISE, which contains an inverted repeat of the attR1-ccdB-attR2 cassette for in vitro recombination and a pentameric GAL4 binding site for conditional expression. These features enabled us to construct RNAi transgenes without a complicated cloning scheme. In cultured cells and transgenic flies, pRISE constructs carrying dsRNA transgenes induced effective RNAi against an EGFP transgene and the endogenous white gene, respectively. These results indicate that pRISE is a convenient transformation vector for studies of multiple Drosophila genes for which functional information is lacking.

ATP-Binding Cassette Transporters↗
PubMed2005

Bruno-like protein is localized to zebrafish germ plasm during the early cleavage stages.

Maternally supplied germ plasm is essential for germ lineage establishment in many species, but the molecular details are still largely unknown, especially in vertebrates, and identification of novel factors that localize to germ plasm is desirable. We previously reported that one of the components of zebrafish germ plasm is mRNA of the bruno-like (brul) gene, a homologue of bruno, which, in Drosophila, is known to participate in germ lineage establishment. Here, we show that not only mRNA but also protein of brul is localized to the zebrafish germ plasm at the ends of the cleavage furrows. In 4- and 8-cell stage embryos, Brul protein is localized to the periphery of the blastomeres, as well as to the ends of the cleavage furrows, forming numerous minute particles. These particles appear at the cortex of the fertilized egg within 10 min after fertilization. Surprisingly, these distinctive localizations, as well as the minute particles, completely disappeared by the 16-cell stage, although relatively weak expression was detected ubiquitously throughout embryogenesis. This is the first report of a protein that localizes to the germ plasm in zebrafish.

Animals↗
PubMed2005

Identification and expression analysis of putative mRNA-like non-coding RNA in Drosophila.

One of the most surprising results to emerge from mammalian cDNA sequencing projects is that thousands of mRNA-like non-coding RNAs (ncRNAs) are expressed and constitute at least 10% of poly(A)(+) RNAs. In most cases, however, the functions of these RNA molecules remain unclear. To clarify the biological significance of mRNA-like ncRNAs, we computationally screened 11,691 Drosophila melanogaster full-length cDNAs. After eliminating presumable protein-coding transcripts, 136 were identified as strong candidates for mRNA-like ncRNAs. Although most of these putative ncRNAs are found throughout the Drosophila genus, predicted amino acid sequences are not conserved even in related species, suggesting that these transcripts are actually non-coding RNAs. In situ hybridization analyses revealed that 35 of the transcripts are expressed during embryogenesis, of which 27 were detected only in specific tissues including the tracheal system, midgut primordial cells, visceral mesoderm, germ cells and the central and peripheral nervous system. These highly regulated expression patterns suggest that many mRNA-like ncRNAs play important roles in multiple steps of organogenesis and cell differentiation in Drosophila. This is the first report that the majority of mRNA-like ncRNAs in a model organism are expressed in specific tissues and cell types.

Amino Acid Sequence↗
PubMed2003

Sequence-specific targeting of Drosophila roX genes by the MSL dosage compensation complex.

MSL complexes bind the single male X chromosome in Drosophila to increase transcription approximately 2-fold. Complexes contain at least five proteins and two noncoding RNAs, roX1 and roX2. The mechanism of X chromosome binding is not known. Here, we identify a 110 bp sequence in roX2 characterized by high-affinity MSL binding, male-specific DNase I hypersensitivity, a shared consensus with the otherwise dissimilar roX1 gene, and conservation across species. Mutagenesis of evolutionarily conserved sequences diminishes MSL binding in vivo. MSL binding to these sites is roX RNA dependent, suggesting that complexes become competent for binding only after incorporation of roX RNAs. However, the roX RNA segments homologous to the DNA binding sites are not required, ruling out simple RNA-DNA complementarity as the primary targeting mechanism. Our results are consistent with a model in which nascent roX RNA assembly with MSL proteins is an early step in the initiation of dosage compensation.

Animals↗
PubMed2003

Dmaf, a novel member of Maf transcription factor family is expressed in somatic gonadal cells during embryonic development and gametogenesis in Drosophila.

Members of the maf gene family encode basic/leucine zipper transcription factors and play important roles during cell differentiation and organogenesis in vertebrate development. In this study, we show that the maf family is evolutionarily conserved and that the Drosophila maf (Dmaf) gene is expressed in somatic gonadal cells. During embryonic development, Dmaf mRNA is detected in somatic gonadal precursor cells emerging from dorsolateral mesoderm. Relatively weak expression is also observed in subset of neuronal cells in the central nervous system. In adult flies, Dmaf is expressed in somatic gonadal cells surrounding developing oocytes and spermatocytes. These results suggest a specific function for Dmaf in gonadal development, including migration and differentiation of primordial germ cells.

Amino Acid Sequence↗
PubMed2002

The stability of the lens-specific Maf protein is regulated by fibroblast growth factor (FGF)/ERK signaling in lens fiber differentiation.

Fibroblast growth factor (FGF) signaling is necessary for both proliferation and differentiation of lens cells. However, the molecular mechanisms by which FGFs exert their effects on the lens remain poorly understood. In this study, we show that FGF-2 repressed the expression of lens-specific genes at the proliferative phase in primary cultured lens cells. Using transfected cells, we also found that the activity of L-Maf, a lens differentiation factor, is repressed by FGF/ERK signaling. L-Maf is shown to be phosphorylated by ERK, and introduction of mutations into the ERK target sites on L-Maf promotes its stabilization. The stable L-Maf mutant protein promotes the differentiation of lens cells from neural retina cells. Taken together, these results indicate that FGF/ERK signaling negatively regulates the function of L-Maf in proliferative lens cells and that stabilization of the L-Maf protein is important for lens fiber differentiation.

Animals↗