Drosophila Spag is the homolog of RNA polymerase II-associated protein 3 (RPAP3) and recruits the heat shock proteins 70 and 90 (Hsp70 and Hsp90) during the assembly of cellular machineries.

The R2TP is a recently identified Hsp90 co-chaperone, composed of four proteins as follows: Pih1D1, RPAP3, and the AAA(+)-ATPases RUVBL1 and RUVBL2. In mammals, the R2TP is involved in the biogenesis of cellular machineries such as RNA polymerases, small nucleolar ribonucleoparticles and phosphatidylinositol 3-kinase-related kinases. Here, we characterize the spaghetti (spag) gene of Drosophila, the homolog of human RPAP3.

Cep63 recruits Cdk1 to the centrosome: implications for regulation of mitotic entry, centrosome amplification, and genome maintenance.

Centrosomes are central regulators of mitosis that are often amplified in cancer cells. Centrosomes function both as organizers of the mitotic spindle and as reaction centers to trigger activation of Cdk1 and G(2)/M transition in the cell cycle, but their functional organization remains incomplete. Recent proteomic studies have identified novel components of the human centrosome including Cep63, a protein of unknown function that Xenopus studies have implicated in mitotic spindle assembly and spindle inactivation after DNA damage.

Microcephalin and pericentrin regulate mitotic entry via centrosome-associated Chk1.

Primary microcephaly, Seckel syndrome, and microcephalic osteodysplastic primordial dwarfism type II (MOPD II) are disorders exhibiting marked microcephaly, with small brain sizes reflecting reduced neuron production during fetal life. Although primary microcephaly can be caused by mutations in microcephalin (MCPH1), cells from patients with Seckel syndrome and MOPD II harbor mutations in ataxia telangiectasia and Rad3 related (ATR) or pericentrin (PCNT), leading to disturbed ATR signaling. In this study, we show that a lack of MCPH1 or PCNT results in a loss of Chk1 from centrosomes with subsequently deregulated activation of centrosomal cyclin B-Cdk1.

The DrosDel deletion collection: a Drosophila genomewide chromosomal deficiency resource.

We describe a second-generation deficiency kit for Drosophila melanogaster composed of molecularly mapped deletions on an isogenic background, covering approximately 77% of the Release 5.1 genome. Using a previously reported collection of FRT-bearing P-element insertions, we have generated 655 new deletions and verified a set of 209 deletion-bearing fly stocks.

Gadd45a promotes epigenetic gene activation by repair-mediated DNA demethylation.

DNA methylation is an epigenetic modification that is essential for gene silencing and genome stability in many organisms. Although methyltransferases that promote DNA methylation are well characterized, the molecular mechanism underlying active DNA demethylation is poorly understood and controversial. Here we show that Gadd45a (growth arrest and DNA-damage-inducible protein 45 alpha), a nuclear protein involved in maintenance of genomic stability, DNA repair and suppression of cell growth, has a key role in active DNA demethylation.

Epigenetic regulation in Drosophila.

Epigenetic regulation of gene transcription relies on molecular marks like DNA methylation or histone modifications. Here we review recent advances in our understanding of epigenetic regulation in the fruit fly Drosophila melanogaster. In the past, DNA methylation research has primarily utilized mammalian model systems.

The Drosophila MBD2/3 protein mediates interactions between the MI-2 chromatin complex and CpT/A-methylated DNA.

Methyl-DNA binding proteins play an important role in epigenetic gene regulation. The Drosophila genome encodes a single protein (MBD2/3) with extended homologies to the vertebrate methyl-DNA binding proteins MBD2 and MBD3. However, very little is known about its functional properties.

The Drosophila methyl-DNA binding protein MBD2/3 interacts with the NuRD complex via p55 and MI-2.

Background: Methyl-DNA binding proteins help to translate epigenetic information encoded by DNA methylation into covalent histone modifications. MBD2/3 is the only candidate gene in the Drosophila genome with extended homologies to mammalian MBD2 and MBD3 proteins, which represent a co-repressor and an integral component of the Nucleosome Remodelling and Deacetylase (NuRD) complex, respectively. An association of Drosophila MBD2/3 with the Drosophila NuRD complex has been suggested previously.

Conservation of DNA methylation in dipteran insects.

DNA methylation is a central mechanism of epigenetic regulation. Whereas vertebrate DNA methylation requires at least four different DNA methyltransferases, Drosophila melanogaster only utilizes a single, Dnmt2-like enzyme. This profound difference has raised the question of the evolutionary significance of the Drosophila methylation system.

A Dnmt2-like protein mediates DNA methylation in Drosophila.

The methylation status of Drosophila DNA has been discussed controversially over a long time. Recent evidence has provided strong support for the existence of 5-methylcytosine in DNA preparations from embryonic stages of fly development. The Drosophila genome contains a single candidate DNA methyltransferase gene that has been termed Dnmt2.

Requirements for scribble expression in newly formed gonads of Drosophila embryos.

The tumour suppressor gene scribble (scrib) is required for epithelial polarity and growth control in Drosophila, and encodes two protein isoforms. Here, we report the pattern of Scrib1 synthesis in pole cells and embryonic gonads. We found that Scrib1 synthesis became strongly enhanced in pole cells at the time of gonad formation and was also detectable in cortical domains of gonadal mesodermal cells adjacent to pole cells.

Knockout targeting of the Drosophila nap1 gene and examination of DNA repair tracts in the recombination products.

We used ends-in gene targeting to generate knockout mutations of the nucleosome assembly protein 1 (Nap1) gene in Drosophila melanogaster. Three independent targeted null-knockout mutations were produced. No wild-type NAP1 protein could be detected in protein extracts.

Stage-specific chromosomal association of Drosophila dMBD2/3 during genome activation.

The Drosophila gene dMBD2/3 encodes a protein with significant homologies to the mammalian methyl-DNA binding proteins MBD2 and MBD3. These proteins are essential components of chromatin complexes involved in epigenetic gene regulation. Because the available in vitro data on dMBD2/3 are conflicting we have started an in vivo characterization of dMBD2/3.

Kremen proteins are Dickkopf receptors that regulate Wnt/beta-catenin signalling.

The Wnt family of secreted glycoproteins mediate cell cell interactions during cell growth and differentiation in both embryos and adults. Canonical Wnt signalling by way of the beta-catenin pathway is transduced by two receptor families. Frizzled proteins and lipoprotein-receptor-related proteins 5 and 6 (LRP5/6) bind Wnts and transmit their signal by stabilizing intracellular beta-catenin.

Differential expression of two scribble isoforms during Drosophila embryogenesis.

The tumour suppressor gene scribble (scrib) is required for epithelial polarity and growth control in Drosophila. Here, we report the identification and embryonic expression pattern of two Scrib protein isoforms resulting from alternative splicing during scrib transcription. Both proteins are first ubiquitously expressed during early embryogenesis.