Deneddylase 1 regulates deneddylase activity of the Cop9 signalosome in Drosophila melanogaster.

NEDD8 conjugation of Cullin has an important role in ubiquitin-mediated protein degradation. The COP9 signalosome, of which CSN5 is the major catalytic subunit, is a major Cullin deneddylase. Another deneddylase, Deneddylase 1, has also been shown to process the Nedd8 precursor. In Drosophila, the DEN1 mutants do not have increased levels of Cullin neddylation, but instead show a significant decrease in neddylated Cullin. This characteristic decrease in neddylated Cullins in the DEN1null background can be rescued by UAS-dDEN1WT overexpression but not by overexpression of mature NEDD8, indicating that this phenotype is distinct from the NEDD8-processing function of DEN1. We examined the role of DEN1-CSN interaction in regulating Cullin neddylation. Overexpression of DEN1 in a CSN5hypo background slightly reduced unneddylated Cullin levels. The CSN5, DEN1 double mutation partially rescues the premature lethality associated with the CSN5 single mutation. These results suggest that DEN1 regulates Cullin neddylation by suppressing CSN deneddylase activity.

Acute myeloid leukemia is a disease associated with HLA-C3.

BACKGROUND: We aimed to observe human leukocyte antigen (HLA) associations with human acute myeloid leukemia (AML) in a large population, in order to investigate the roles of HLA in leukemogenesis. Furthermore, we examined the HLA association according to morphological, cytogenetic, immunological, and clinical classifications. MATERIALS AND METHODS: We performed HLA genotyping, bone marrow studies, cytogenetic analyses, and fluorescence-activated cell sorting analyses. A clinical outcome database was constructed, and the HLA frequency, gene frequency, relative risk (RR), linkage disequilibrium, and the 2-locus and 3-locus haplotype frequency using the Mattiuz formula were calculated. For the healthy controls, Korean HLA data published by Park and co-workers were used. RESULTS: AML was found to be associated with HLA-C3 (RR = 1.46; p < 0.001). In the French-American-British (FAB) classification, acute myelomonocytic leukemia (AML-M4) was associated with HLA-C3 (47.2 vs. 74.1%; RR = 3.13; p = 0.005), in cytogenetic classification, del(9), which is frequently observed in AML-M4, was also associated with HLA-C3 (47.2 vs. 100%; RR = 13.43; p = 0.024), and in clinical classification, incomplete remission was associated with HLA-C3 as well (47.2 vs. 63.2%; RR = 1.92; p = 0.002). No correlations between AML and immunological classifications were observed. Moreover, and in terms of 2-locus haplotypes, AML was found to be associated with HLA-C3/B62 (HLA-C3 gene frequency 0.3415; HLA-B62 gene frequency 0.1361; linkage disequilibrium 0.0136; haplotype frequency 4.15 vs. 6.0%; p < 0.05). In clinical classification, incomplete remission (linkage disequilibrium 0.0136; haplotype frequency 4.15 vs. 13.6%; p = 0.013) and relapse (linkage disequilibrium 0.0136; haplotype frequency 4.15 vs. 71.0%; p = 0.044) were associated with HLA-C3/B62, whereas no association was observed for FAB, cytogenetic and immunological classifications. No association was observed for the 3-locus haplotype. CONCLUSION: The HLA-C3 antigen and the 2-locus haplotype are associated with AML.

Sexual material perception in sexually coercive men: disattending deficit and its covariates.

The perceptual bias for sexual material has been explored mainly in normal men, and to date little attention has been paid to sexually aggressive men. The current study compared performance of sexually aggressive and nonaggressive men on experimental tasks involving sexual stimuli. Participants viewed the visual images (neutral or sexual), and, depending on the cue they were presented, they either responded to shape and color questions or just skipped to the next trial. In contrast with noncoercive men, men who admitted sexually coercive behavior showed increased response latencies only in the condition in which they were required to withdraw their attention from sexual stimuli to perform the cognitive task. Correlations with attentional performance suggested that sexually coercive men high on impulsivity and aggressiveness might experience cognitive interference when processing sexual material. These results are interpreted using disinhibition and response modulation models.

Down-regulation of FoxO-dependent c-FLIP expression mediates TRAIL-induced apoptosis in activated hepatic stellate cells.

Activated hepatic stellate cells which contribute to liver fibrosis have represented an important target for antifibrotic therapy. In this study, we found that TRAIL inhibited PI3K/Akt-dependent FoxO phosphorylation and relocated FoxO proteins into the nucleus from the cytosol in activated human hepatic stellate LX-2 cells. The accumulated FoxO proteins in the nucleus led to down-regulation of c-FLIP(L/S) expression, resulting in the activation of apoptosis-related signaling molecules including the activation of caspase-8, -3, and Bid, as well as mitochondrial cytochrome c release. These results were supported by showing that siRNA-mediated knockdown of FoxO led to restoration of c-FLIP(L/S) expression and resistance to TRAIL-induced apoptosis after treatment of LX-2 cells with TRAIL. Furthermore, c-FLIP(L/S)-transfected LX-2 cells showed the decreased sensitivity to TRAIL-induced apoptosis. Collectively, our data suggest that sequential activation of FoxO proteins under conditions of suppressed PI3K/Akt signaling by TRAIL can down-regulate c-FLIP(L/S), consequently promoting TRAIL-induced apoptosis in LX-2 cells. Therefore, the present study suggests TRAIL may be an effective strategy for antifibrotic therapy in liver fibrosis.

DEN1 deneddylates non-cullin proteins in vivo.

The ubiquitin-like protein Nedd8/Rub1 covalently modifies and activates cullin ubiquitin ligases. However, the repertoire of Nedd8-modified proteins and the regulation of protein neddylation status are not clear. The cysteine protease DEN1/NEDP1 specifically processes the Nedd8 precursor and has been suggested to deconjugate Nedd8 from cullin proteins. By characterizing the Drosophila DEN1 protein and DEN1 null (DEN1(null)) mutants, we provide in vitro and in vivo evidence that DEN1, in addition to processing Nedd8, deneddylates many cellular proteins. Although purified DEN1 protein efficiently deneddylates the Nedd8-conjugated cullin proteins Cul1 and Cul3, neddylated Cul1 and Cul3 protein levels are not enhanced in DEN1(null). Strikingly, many cellular proteins are highly neddylated in DEN1 mutants and are deneddylated by purified DEN1 protein. DEN1 deneddylation activity is distinct from that of the cullin-deneddylating CSN. Genetic analyses indicate that a balance between neddylation and deneddylation maintained by DEN1 is crucial for animal viability.

The balance between the novel protein target of wingless and the Drosophila Rho-associated kinase pathway regulates planar cell polarity in the Drosophila wing.

Planar cell polarity (PCP) signaling is mediated by the serpentine receptor Frizzled (Fz) and transduced by Dishevelled (Dsh). Wingless (Wg) signaling utilizes Drosophila Frizzled 2 (DFz2) as a receptor and also requires Dsh for transducing signals to regulate cell proliferation and differentiation in many developmental contexts. Distinct pathways are activated downstream of Dsh in Wg- and Fz-signaling pathways. Recently, a number of genes, which have essential roles as downstream components of PCP signaling, have been identified in Drosophila. They include the small GTPase RhoA/Rho1, its downstream effector Drosophila rho-associated kinase (Drok), and a number of genes such as inturned (in) and fuzzy (fy), whose biochemical functions are unclear. RhoA and Drok provide a link from Fz/Dsh signaling to the modulation of actin cytoskeleton. Here we report the identification of the novel gene target of wingless (tow) by enhancer trap screening. tow expression is negatively regulated by Wg signaling in wing imaginal discs, and the balance between tow and the Drok pathway regulates wing-hair morphogenesis. A loss-of-function mutation in tow does not result in a distinct phenotype. Genetic interaction and gain-of-function studies provide evidence that Tow acts downstream of Fz/Dsh and plays a role in restricting the number of hairs that wing cells form.

Ectopic expression of Tollo/Toll-8 antagonizes Dpp signaling and induces cell sorting in the Drosophila wing.

The wing imaginal disc of Drosophila consists of the primordia for the adult wing and the body wall. The zinc-finger transcription factor Teashirt (Tsh) is expressed in the region proximal to the wing primordium and regulates the formation of the wing-body wall boundary. Here, we report that Tollo/Toll-8, a member of Toll family transmembrane proteins, is also expressed proximal to the wing domain. Ectopic expression of Decapentaplegic (Dpp), a morphogen for wing development, represses tollo expression in the proximal domain. Likewise, misexpression of Tollo in the presumptive wing strongly antagonizes the effects of Dpp signaling. The extracellular domain of Tollo containing the Leucine-Rich Repeats (LRR) is required for the inhibition of Dpp signaling in the wing. Furthermore, clones of cells with Tollo overexpression are sorted out from the surrounding wild-type cells, resulting in the formation of epithelial folds around the clone boundaries. Tsh is ectopically induced at the border of Tollo-expressing clones. Despite the strong effects of Tollo overexpression on Dpp signaling and cell sorting, loss-of-function tollo mutants are viable with normal external morphology. Our data suggest that Tollo function might be redundant but is sufficient to antagonize Dpp signaling and induce sorting of Tollo expressing cells from the wing cells to develop proximal cell fate.