The acetyltransferase activity of Drosophila CBP is dispensable for regulation of the Dpp pathway in the early embryo

AbstractThe CBP protein is a transcriptional co-activator and histone acetyltransferase. Reduced expression of Drosophila CBP (dCBP) in the early embryo specifically impairs signaling by the TGF-β molecules Dpp and Screw (Scw). This occurs by a failure to activate transcription of the tolloid (tld) gene, which codes for a protease that generates active Dpp and Scw ligands. We show that dCBP directly regulates this gene by binding to the tld enhancer, and that tld expression can be partially rescued with a dCBP transgene. At a slightly later stage of development, Dpp/Scw signaling recovers in mutant embryos, but is unable to turn on expression of the Dpp/Scw-target gene rhomboid (rho). Interestingly, an acetyltransferase (AT)-defective dCBP transgene rescued tld and rho gene expression to an extent comparable to the wild-type transgene, whereas a transgene containing a 130 amino acid deletion rescued tld but not late rho expression. A tracheal phenotype caused by the reduced dCBP levels was also rescued more efficiently with the wild-type dCBP transgene than with this mutant transgene. Our results indicate that separate parts of the dCBP protein are required on different promoters, and that the AT activity of dCBP is dispensable for certain aspects of Dpp signaling. We discuss the similarity of these results to the role of p300/CBP in TGF-β signaling in the mouse

Behavioral Cost-Based Recommendation Model for Wanderers in Town

Abstract. This paper proposes a new model for recommendation based on the behavioral cost of recommendees in town. The model is based on cost-benefit analysis of the information provided to the user, referring to the model of temporal discounting and preference reversal. Here we assume that behavioral cost may be regarded as time in temporal discounting. A recommender system based on this model can select information, which is located in the surrounding area (not so far away) and may be preferred by the user, if the system can estimate where the reversal phenomenon may occur. The experiments were made using an experimental social service, called "pin@clip", which is an iPhone-based social bookmarking service in Shibuya, Tokyo, Japan that has been operating since December 2009. The experimental results show that the phenomenon of preference reversals might occur, even though the authors could not obtain statistically significant data

Akirin Links Twist-Regulated Transcription with the Brahma Chromatin Remodeling Complex during Embryogenesis

The activities of developmentally critical transcription factors are regulated via interactions with cofactors. Such interactions influence transcription factor activity either directly through protein–protein interactions or indirectly by altering the local chromatin environment. Using a yeast double-interaction screen, we identified a highly conserved nuclear protein, Akirin, as a novel cofactor of the key Drosophila melanogaster mesoderm and muscle transcription factor Twist. We find that Akirin interacts genetically and physically with Twist to facilitate expression of some, but not all, Twist-regulated genes during embryonic myogenesis. akirin mutant embryos have muscle defects consistent with altered regulation of a subset of Twist-regulated genes. To regulate transcription, Akirin colocalizes and genetically interacts with subunits of the Brahma SWI/SNF-class chromatin remodeling complex. Our results suggest that, mechanistically, Akirin mediates a novel connection between Twist and a chromatin remodeling complex to facilitate changes in the chromatin environment, leading to the optimal expression of some Twist-regulated genes during Drosophila myogenesis. We propose that this Akirin-mediated link between transcription factors and the Brahma complex represents a novel paradigm for providing tissue and target specificity for transcription factor interactions with the chromatin remodeling machinery

骨肉腫細胞の生存と増殖はミトコンドリア局在BIG3-PHB2複合体形成に依存する

Previous studies reported the critical role of the brefeldin A–inhibited guanine nucleotide exchange protein 3–prohibitin 2 (BIG3-PHB2) complex in modulating estrogen signaling activation in breast cancer cells, yet its pathophysiological roles in osteosarcoma (OS) cells remain elusive. Here, we report a novel function of BIG3-PHB2 in OS malignancy. BIG3-PHB2 complexes were localized mainly in mitochondria in OS cells, unlike in estrogen-dependent breast cancer cells. Depletion of endogenous BIG3 expression by small interfering RNA (siRNA) treatment led to significant inhibition of OS cell growth. Disruption of BIG3-PHB2 complex formation by treatment with specific peptide inhibitor also resulted in significant dose-dependent suppression of OS cell growth, migration, and invasion resulting from G2/M-phase arrest and in PARP cleavage, ultimately leading to PARP-1/apoptosis-inducing factor (AIF) pathway activation–dependent apoptosis in OS cells. Subsequent proteomic and bioinformatic pathway analyses revealed that disruption of the BIG3-PHB2 complex might lead to downregulation of inner mitochondrial membrane protein complex activity. Our findings indicate that the mitochondrial BIG3-PHB2 complex might regulate PARP-1/AIF pathway-dependent apoptosis during OS cell proliferation and progression and that disruption of this complex may be a promising therapeutic strategy for OS

SGLT2阻害薬であるイプラグリフロジンは2型糖尿病自然発症モデルであるOLETFラットにおいて肝線維化進展を抑制する。

BACKGROUND: It is widely understood that insulin resistance (IR) critically correlates with the development of liver fibrosis in several types of chronic liver injuries. Several experiments have proved that anti-IR treatment can alleviate liver fibrosis. Sodium-glucose cotransporter 2 (SGLT2) inhibitors comprise a new class of antidiabetic agents that inhibit glucose reabsorption in the renal proximal tubules, improving IR. The aim of this study was to elucidate the effect of an SGLT2 inhibitor on the development of liver fibrosis using obese diabetic Otsuka Long-Evans Tokushima fatty (OLETF) rats and their littermate nondiabetic Long-Evans Tokushima Otsuka (LETO) rats. METHODS: Male OLETF and LETO rats were intraperitoneally injected with porcine serum twice a week for 12 weeks to augment liver fibrogenesis. Different concentrations of ipragliflozin (3 and 6 mg/kg) were orally administered during the experimental period. Serological and histological data were examined at the end of the experimental period. The direct effect of ipragliflozin on the proliferation of a human hepatic stellate cell (HSC) line, LX-2, was also evaluated in vitro. RESULTS: OLETF rats, but not LETO rats, received 12 weeks of porcine serum injection to induce severe fibrosis. Treatment with ipragliflozin markedly attenuated the development of liver fibrosis and expression of hepatic fibrosis markers, such as alpha smooth muscle actin, collagen 1A1, and transforming growth factor beta (TGF-β), and improved IR in a dose-dependent manner in OLETF rats. In contrast, the proliferation of LX-2 in vitro was not affected, suggesting that ipragliflozin had no significant direct effect on the proliferation of HSCs. CONCLUSION: In conclusion, our dataset suggests that an SGLT2 inhibitor could alleviate the development of liver fibrosis by improving IR in naturally diabetic rats. This may provide the basis for creating new therapeutic strategies for chronic liver injuries with IR.博士（医学）・甲第665号・平成29年3月15日© Japanese Society of Gastroenterology 2016The final publication is available at Springer via http://dx.doi.org/10.1007/s00535-016-1200-6

非アルコール性脂肪肝炎（NASH）モデルのラットにおいて、エンドトキシンの減少が肝星細胞の活性化抑制と腸管透過性改善を介して肝線維化進展を抑制する。

Previous clinical studies have demonstrated that endotoxin/toll‑like receptor 4 (TLR4) signaling is critical in the inflammatory pathways associated with non‑alcoholic steatohepatitis (NASH). In human and animal studies, NASH was associated with portal lipopolysaccharide (LPS) and the plasma LPS level was hypothesized to be associated with small intestinal bacterial overgrowth, change in composition of the microbiota and increased intestinal permeability. The aim of the present study was to investigate the roles of endogenous endotoxin and TLR4 in the pathogenesis of NASH. The effects of antibiotics were assessed in vivo using a choline deficiency amino acid (CDAA)‑induced experimental liver fibrosis model. Antibiotics, including polymyxins and neomycins, were orally administered in drinking water. Antibiotics attenuated hepatic stellate cell (HSC) activation and liver fibrosis via TGF‑β and collagen in an experimental hepatic fibrosis model. The mechanism by which antibiotics attenuated LPS‑TLR4 signaling and liver fibrosis was assessed. Notably, TLR4 mRNA level in the liver was elevated in the CDAA group and the CDAA‑induced increase was significantly reduced by antibiotics. However, no significant differences were observed in the intestine among all groups. Elevated mRNA levels of LPS binding protein, which was correlated with serum endotoxin levels, were recognized in the CDAA group and the CDAA‑induced increase was significantly reduced by antibiotics. The intestinal permeability of the CDAA group was increased compared with the choline‑supplemented amino acid group. The tight junction protein (TJP) in the intestine, determined by immunohistochemical analysis was inversely associated with intestinal permeability. Antibiotics improved the intestinal permeability and enhanced TJP expression. Inhibition of LPS‑TLR4 signaling with antibiotics attenuated liver fibrosis development associated with NASH via the inhibition of HSC activation. These results indicated that reduction of LPS and restoration of intestinal TJP may be a novel therapeutic strategy for treatment of liver fibrosis development in NASH.博士（医学）・甲第628号・平成27年3月16日Copyright: © Douhara et al. This is an open access article distributed under the terms of a Creative Commons Attribution License.The definitive version is available at " http://dx.doi.org/10.3892/mmr.2014.2995