排序方式: 共有283条查询结果,搜索用时 15 毫秒
221.
Reineke J Tenzer S Rupnik M Koschinski A Hasselmayer O Schrattenholz A Schild H von Eichel-Streiber C 《Nature》2007,446(7134):415-419
Clostridium difficile, the causative agent of nosocomial antibiotic-associated diarrhoea and pseudomembranous colitis, possesses two main virulence factors: the large clostridial cytotoxins A and B. It has been proposed that toxin B is cleaved by a cytosolic factor of the eukaryotic target cell during its cellular uptake. Here we report that cleavage of not only toxin B, but also all other large clostridial cytotoxins, is an autocatalytic process dependent on host cytosolic inositolphosphate cofactors. A covalent inhibitor of aspartate proteases, 1,2-epoxy-3-(p-nitrophenoxy)propane, completely blocked toxin B function on cultured cells and was used to identify its catalytically active protease site. To our knowledge this is the first report on a bacterial toxin that uses eukaryotic signals for induced autoproteolysis to deliver its toxic domain into the cytosol of target cells. On the basis of our data, we present an integrated model for the uptake and inositolphosphate-induced activation of toxin B. 相似文献
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Roell W Lewalter T Sasse P Tallini YN Choi BR Breitbach M Doran R Becher UM Hwang SM Bostani T von Maltzahn J Hofmann A Reining S Eiberger B Gabris B Pfeifer A Welz A Willecke K Salama G Schrickel JW Kotlikoff MI Fleischmann BK 《Nature》2007,450(7171):819-824
Ventricular tachyarrhythmias are the main cause of sudden death in patients after myocardial infarction. Here we show that transplantation of embryonic cardiomyocytes (eCMs) in myocardial infarcts protects against the induction of ventricular tachycardia (VT) in mice. Engraftment of eCMs, but not skeletal myoblasts (SMs), bone marrow cells or cardiac myofibroblasts, markedly decreased the incidence of VT induced by in vivo pacing. eCM engraftment results in improved electrical coupling between the surrounding myocardium and the infarct region, and Ca2+ signals from engrafted eCMs expressing a genetically encoded Ca2+ indicator could be entrained during sinoatrial cardiac activation in vivo. eCM grafts also increased conduction velocity and decreased the incidence of conduction block within the infarct. VT protection is critically dependent on expression of the gap-junction protein connexin 43 (Cx43; also known as Gja1): SMs genetically engineered to express Cx43 conferred a similar protection to that of eCMs against induced VT. Thus, engraftment of Cx43-expressing myocytes has the potential to reduce life-threatening post-infarct arrhythmias through the augmentation of intercellular coupling, suggesting autologous strategies for cardiac cell-based therapy. 相似文献
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Crown-group crustaceans (Eucrustacea) are common in the fossil record of the past 500 million years back to the early Ordovician period, and very rare representatives are also known from the late Middle and Late Cambrian periods. Finds in Lower Cambrian rocks of the Phosphatocopina, the fossil sister group to eucrustaceans, imply that members of the eucrustacean stem lineage co-occurred, but it remained unclear whether crown-group members were also present at that time. 'Orsten'-type fossils are typically tiny embryos and cuticle-bearing animals, of which the cuticle is phosphatized and the material is three-dimensional and complete with soft parts. Such fossils are found predominantly in the Cambrian and Ordovician and provide detailed morphological and phylogenetic information on the early evolution of metazoans. Here we report an Orsten-type Konservat-Lagerst?tte from the Lower Cambrian of China that contains at least three new arthropod species, of which we describe the most abundant form on the basis of exceptionally well preserved material of several growth stages. The limb morphology and other details of this new species are markedly similar to those of living cephalocarids, branchiopods and copepods and it is assigned to the Eucrustacea, thus representing the first undoubted crown-group crustacean from the early Cambrian. Its stratigraphical position provides substantial support to the proposition that the main cladogenic event that gave rise to the Arthropoda was before the Cambrian. Small leaf-shaped structures on the outer limb base of the new species provide evidence on the long-debated issue of the origin of epipodites: they occur in a set of three, derive from setae and are a ground-pattern feature of Eucrustacea. 相似文献
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Qingzhen Bian Chiara Musumeci Chuanfei Wang Andreas Skallberg Yongzhen Chen Zhangjun Hu E.Peter Münger Kajsa Uvdal Mats Fahlman Olle Ingans 《科学通报(英文版)》2021,(9):875-879
A key requirement for well performing devices based on organic semiconductors is to ensure ohmic contacts, where an efficient hole and electron injection and ex... 相似文献
227.
Farima Zahedi Maliheh Nazari-Jahantigh Zhe Zhou Pallavi Subramanian Yuanyuan Wei Jochen Grommes Stefan Offermanns Sabine Steffens Christian Weber Andreas Schober 《Cellular and molecular life sciences : CMLS》2017,74(2):359-372
MicroRNAs (miRNAs) coordinate vascular repair by regulating injury-induced gene expression in vascular smooth muscle cells (SMCs) and promote the transition of SMCs from a contractile to a proliferating phenotype. However, the effect of miRNA expression in SMCs on neointima formation is unclear. Therefore, we studied the role of miRNA biogenesis by Dicer in SMCs in vascular repair. Following wire-induced injury to carotid arteries of Apolipoprotein E knockout (Apoe ?/?) mice, miRNA microarray analysis revealed that the most significantly regulated miRNAs, such as miR-222 and miR-21-3p, were upregulated. Conditional deletion of Dicer in SMCs increased neointima formation by reducing SMC proliferation in Apoe ?/? mice, and decreased mainly the expression of miRNAs, such as miR-147 and miR-100, which were not upregulated following vascular injury. SMC-specific deletion of Dicer promoted growth factor and inflammatory signaling and regulated a miRNA–target interaction network in injured arteries that was enriched in anti-proliferative miRNAs. The most connected miRNA in this network was miR-27a-3p [e.g., with Rho guanine nucleotide exchange factor 26 (ARHGEF26)], which was expressed in medial and neointimal SMCs in a Dicer-dependent manner. In vitro, miR-27a-3p suppresses ARHGEF26 expression and inhibits SMC proliferation by interacting with a conserved binding site in the 3′ untranslated region of ARHGEF26 mRNA. We propose that Dicer expression in SMCs plays an essential role in vascular repair by generating anti-proliferative miRNAs, such as miR-27a-3p, to prevent vessel stenosis due to exaggerated neointima formation. 相似文献
228.
Radbruch A 《Cellular and molecular life sciences : CMLS》2012,69(10):1563-1564
229.
Cízková A Stránecký V Mayr JA Tesarová M Havlícková V Paul J Ivánek R Kuss AW Hansíková H Kaplanová V Vrbacký M Hartmannová H Nosková L Honzík T Drahota Z Magner M Hejzlarová K Sperl W Zeman J Houstek J Kmoch S 《Nature genetics》2008,40(11):1288-1290
We carried out whole-genome homozygosity mapping, gene expression analysis and DNA sequencing in individuals with isolated mitochondrial ATP synthase deficiency and identified disease-causing mutations in TMEM70. Complementation of the cell lines of these individuals with wild-type TMEM70 restored biogenesis and metabolic function of the enzyme complex. Our results show that TMEM70 is involved in mitochondrial ATP synthase biogenesis in higher eukaryotes. 相似文献
230.
A genome-wide association scan of nonsynonymous SNPs identifies a susceptibility variant for Crohn disease in ATG16L1 总被引:16,自引:0,他引:16
Hampe J Franke A Rosenstiel P Till A Teuber M Huse K Albrecht M Mayr G De La Vega FM Briggs J Günther S Prescott NJ Onnie CM Häsler R Sipos B Fölsch UR Lengauer T Platzer M Mathew CG Krawczak M Schreiber S 《Nature genetics》2007,39(2):207-211
We performed a genome-wide association study of 19,779 nonsynonymous SNPs in 735 individuals with Crohn disease and 368 controls. A total of 7,159 of these SNPs were informative. We followed up on all 72 SNPs with P 0.4), these data suggest that the underlying biological process may be specific to Crohn disease. 相似文献