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931.
Gol Nam Yi Shi Myongchol Ryu Qihui Wang Hao Song Jun Liu Jinghua Yan Jianxun Qi George F Gao 《蛋白质与细胞》2013,4(10):761
Leukocyte immunoglobulin-like receptors (LILRs), also called CD85s, ILTs, or LIRs, are important mediators of immune activation and tolerance that contain tandem immunoglobulin (Ig)-like folds. There are 11 (in addition to two pseudogenes) LILRs in total, two with two Ig-like domains (D1D2) and the remaining nine with four Ig-like domains (D1D2D3D4). Thus far, the structural features of the D1D2 domains of LILR proteins are well defi ned, but no structures for the D3D4 domains have been reported. This is a very important fi eld to be studied as it relates to the unknown functions of the D3D4 domains, as well as their relative orientation to the D1D2 domains on the cell surface. Here, we report the crystal structures of the D3D4 domains of both LILRB1 and LILRB2. The two Iglike domains of both LILRB1-D3D4 and LILRB2-D3D4 are arranged at an acute angle (~60°) to form a bent structure, resembling the structures of natural killer inhibitory receptors. Based on these two D3D4 domain structures and previously reported D1D2/HLA I complex structures, two alternative models of full-length (four Ig-like domains) LILR molecules bound to HLA I are proposed. 相似文献
932.
Kim S Moon SM Kim YS Kim JJ Ryu HJ Kim YJ Choi JW Park HS Kim DG Shin HD Rutherford MS Oh B Lee JK 《Biochemical and biophysical research communications》2008,368(2):395-401
Tumor necrosis factor (TNF) and the TNF receptor (TNFR) superfamily play very important roles for cell death as well as normal immune regulation. Dysregulation of TNF-TNFR superfamily gene expression will influence many biological processes, and contributes to human diseases, including cancer. We investigated the genetic alterations of the TNF-TNFR superfamily genes in hepatocellular carcinoma (HCC). Several genetic alterations were detected in the 44 TNF-TNFR superfamily genes by sequencing hepatocellular carcinoma DNA samples. In particular, we found that the TNFR1 promoter −329G/T polymorphism was strongly associated with primary HCC (odds ratio [OR] = 5.22, p = 0.0007). We also observed frequent loss of heterozygosity at the polymorphic TNFR1 −329G/T site in the primary tumor tissues, indicating that the polymorphic TNFR1 −329G/T site is very susceptible to genetic alterations in HCC. Furthermore, in the polymorphic TNFR1 −329G/T site, the T allele resulted in the repression of TNFR1 expression. Therefore, our results suggest that TNFR1 −329G/T polymorphism may play an important role in the development of HCC. 相似文献
933.
934.
Recently discovered evidences suggest that precipitation of Alzheimer's beta-amyloid (Abeta) peptide and the toxicity in Alzheimer's disease (AD) are caused by abnormal interactions with neocortical metal ions, especially Zn2+, Cu2+, and Fe3+. While many studies had focused on the role of a "single" metal ion and its interaction with Abeta peptides, such studies involving "multiple" metal ions have hardly been explored. Here, to explore the nature of codeposition of different metals, two or more metal ions along with Abeta were incubated over a solid template prepared by immobilizing Abeta42 oligomers. The influence of Zn2+,Cu2+, and Fe3+ on Abeta aggregation was investigated by two approaches: co-incubation and sequential addition. Our results using ex situ AFM, ThT-induced fluorescence, and FTIR spectroscopy indicated that the co-incubation of Cu2+, Zn2+, and Fe3+ significantly altered the morphology of aggregates. A concentration dependence study with mixed metal ions suggested that Zn2+ was required at much lower concentrations than Cu2+ to yield nonfibrillar amorphous Abeta deposits. In addition, sequential addition of Zn2+ or Cu2+ on fibrillar aggregates formed by Fe3+ demonstrated that Zn2+ and Cu2+ could possibly change the conformation of the aggregates induced by Fe3+. Our findings elucidate the coexistence of multiple metal ions through their interactions with Abeta peptides or its aggregates. 相似文献
935.
It was hypothesized that histone deacetylase (HDAC) inhibitors may increase survival after total-body irradiation (TBI) based on previous reports demonstrating that HDAC inhibitors stimulate the proliferation of bone marrow stem cells. Using the time for mice to lose 20% or more of their weight as the end point, two HDAC inhibitors, valproic acid and trichostatin-A, were found to reduce lethality in a dose-dependent manner. HDAC inhibitors were effective at reducing lethality when given either 24 h before or 1 h after TBI. The results indicate that HDAC inhibitors have potential for protecting against and mitigating radiation-induced lethality. 相似文献
936.
There are many neutrophils in the vaginal discharge from women infected with Trichomonas vaginalis. The aim of our study was to determine whether human neutrophil apoptosis may be regulated by reactive oxygen species (ROS) in response to trichomonads infection. Incubation of human neutrophils with live trichomonads caused marked receptor shedding of CD16, decrease of mitochondrial membrane potential (MMP) and caspase-3 activation in human neutrophils. These proapoptotic effects of T. vaginalis on neutrophils were inhibited by pretreatment of neutrophils with an inhibitor of NADPH oxidase, diphenyleneiodonium chloride (DPI), suggesting an important role of intracellular ROS accumulation in T. vaginalis-triggered apoptosis. Indeed, large amounts of ROS levels were detected in neutrophils incubated with live trichomonads, and were also effectively inhibited by DPI. However, pan-caspase inhibitor z-VAD-fmk or caspase-3 inhibitor z-DEVD-fmk did not affect T. vaginalis-induced ROS generation in neutrophils. These results suggest that ROS-dependent caspase-3 activation plays an important role in apoptosis of human neutrophils induced by T. vaginalis. 相似文献
937.
Yun S Möller A Chae SK Hong WP Bae YJ Bowtell DD Ryu SH Suh PG 《The Journal of biological chemistry》2008,283(2):1034-1042
Phospholipase Cepsilon (PLCepsilon) is activated by various growth factors or G-protein-coupled receptor ligands via different activation mechanisms. The Ras association (RA) domain of PLCepsilon is known to be important for its ability to bind with Ras-family GTPase upon growth factor stimulation. In the present study, we identified Siah1 and Siah2 as novel binding partners of the PLCepsilon RA domain. Both Siah1 and Siah2 interacted with the RA2 domain of PLCepsilon, and the mutation of Lys-2186 of the PLCepsilon RA2 domain abolished this association. Moreover, Siah induced the ubiquitination and degradation of PLCepsilon upon epidermal growth factor (EGF) stimulation, and Siah proteins were phosphorylated on multiple tyrosine residues via an Src-dependent pathway upon EGF treatment. The Src inhibitor abolished the EGF-dependent ubiquitination of PLCepsilon, and the Siah1 phosphorylation-deficient mutant could not increase the EGF-dependent ubiquitination and degradation of PLCepsilon. The EGF-dependent degradation of PLCepsilon was blocked in mouse embryonic fibroblast (MEF) cells derived from Siah1a/Siah2 double knockout mice, and the extrinsic expression of wild-type Siah1 restored the degradation of PLCepsilon, whereas the phosphorylation-deficient mutant did not. Siah1 expression abolished PLCepsilon-dependent potentiation of EGF-dependent cell growth. In addition, the expression of wild-type Siah1 in Siah1a/Siah2-double knockout MEF cells inhibited EGF-dependent cell growth, and this inhibition was abolished by PLCepsilon knockdown. Our results suggest that the Siah-dependent degradation of PLCepsilon plays a role in the regulation of growth factor-dependent cell growth. 相似文献
938.
We investigated whether changes in sucrose-phosphate synthase (EC 2.4.1.14, SPS) activity could alter N remobilization during leaf senescence. Transgenic rice (Oryza sativa L. cv. Nipponbare) with low SPS activities and wild-type rice plants were grown with basal N (1.0 mM NH4NO3) until the late vegetative stage. Subsequently, half of the plants were transferred to a low N (0.1 mM NH4NO3) condition to accelerate leaf senescence, and the others were continuously grown with basal N. With low N supply, the amounts of chlorophyll and soluble protein in flag leaf blades decreased after anthesis in both the low SPS plants and wild-type plants, although the decrease was less in the low SPS plants. Panicle weights were significantly lower in the low SPS plant than in the wild-type plant. These results suggest that the remobilization of N from flag leaves was diminished by suppressing the development of reproductive sinks in the low SPS plant. 相似文献
939.
Suppression of pepper SGT1 and SKP1 causes severe retardation of plant growth and compromises basal resistance 总被引:1,自引:0,他引:1
Eunsook Chung Choong-Min Ryu Sang-Keun Oh Ryong Nam Kim Jeong Mee Park Hye Sun Cho Sanghyeob Lee Jae Sun Moon Seung-Hwan Park Doil Choi 《Physiologia plantarum》2006,126(4):605-617
SGT1 associates with suppressor of kinetochore protein (Skp1)-Cullin-F-box (SCF)–ubiquitin-ligase complexes playing important roles in controlling developmental processes and defense responses in plants, yeast, and human. In this study, full-length cDNAs of Sgt1 and Skp1 orthologues were isolated from pepper ( Capsicum annuum L.) to characterize their functions. Protein sequences of CaSgt1 and CaSkp1 showed high degrees of similarities with their homologues in other plant species. Southern blot analyses revealed that CaSgt1 was a single copy gene in the pepper genome, whereas CaSkp1 corresponded to multi copy genes. Levels of CaSgt1 and CaSkp1 mRNAs increased in pepper leaves in response to incompatible pathogen challenge or salicylic acid treatment. Silencing of CaSgt1 or CaSkp1 using Tobacco rattle virus-based virus-induced gene-silencing (VIGS) system resulted in severe dwarfism and final damping-off symptom in the greenhouse. To identify factors determining damping-off symptom in CaSgt1 - or CaSkp1 -silenced plants, we employed VIGS under sterile conditions. Under such conditions, damping-off symptom was not observed suggesting that CaSgt1 and CaSkp1 play an essential role in plant growth and development as well as basal disease resistance in pepper plant. 相似文献
940.
Plants protect themselves against pathogens using a range of response mechanisms. There are two categories of nonhost resistance:
Type I, which does not result in visible cell death; and Type II, which entails localized programmed cell death (or hypersensitive
response) in response to nonhost pathogens. The genes responsible for these two systems have not yet been intensively investigated
at the molecular level. Using tobacco plants (Nicotiana tabacum), we compared expression of 12 defense-related genes between a Type I (Xanthomonas axonopodis pv. glycines 8ra) nonhost interaction, and two Type II (Pseudomonas syringae pv. syringae 61 and P. syringae pv. phaseolicola NPS3121) nonhost interactions, as well as those expressed during R gene-mediated resistance to Tobacco mosaic virus. In general, expression of most defense-related genes during R gene-mediated resistance was activated 48 h after challenge by TMV; the same genes were upregulated as early as 9 h after
infiltration by nonhost pathogens. Surprisingly, X. axonopodis pv. glycines (Type I) elicited the same set of defense-related genes as did two pathovars of P. syringae, despite the absence of visible cell death. In two examples of Type II nonhost interactions, P. syringae pv. phaseolicola NPS3121 produced an expression profile more closely resembling that of X. axonopodis pv. glycines 8ra, than that of P. syringae pv. syringae 61. These results suggest that Type I nonhost resistance may act as a mechanism providing a more specific and
active defense response against a broad range of potential pathogens. 相似文献