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991.
Mescalchin A Detzer A Weirauch U Hahnel MJ Engel C Sczakiel G 《RNA (New York, N.Y.)》2010,16(12):2529-2536
The Argonaute proteins play essential roles in development and cellular metabolism in many organisms, including plants, flies, worms, and mammals. Whereas in organisms such as Caenorhabditis elegans and Arabidopsis thaliana, creation of Argonaute mutant strains allowed the study of their biological functions, in mammals the application of this approach is limited by its difficulty and in the specific case of Ago2 gene, by the lethality of such mutation. Hence, in human cells, functional studies of Ago proteins relied on phenotypic suppression using small interfering RNA (siRNA) which involves Ago proteins and the RNA interference mechanism. This bears the danger of undesired or unknown interference effects which may lead to misleading results. Thus, alternative methods acting by different regulatory mechanisms would be advantageous in order to exclude unspecific effects. The knockdown may be achieved by using specific antisense oligonucleotides (asONs) which act via an RNase H-dependent mechanism, not thought to interfere with processes in which Agos are involved. Different functional observations in the use of siRNA versus asONs indicate the relevance of this assumption. We developed asONs specific for the four human Agos (hAgos) and compared their activities with those obtained by siRNA. We confirm that hAgo2 is involved in microRNA (miRNA)- and in siRNA-mediated silencing pathways, while the other hAgos play a role only in miRNA-based gene regulation. Using combinations of asONs we found that the simultaneous down-regulation of hAgo1, hAgo2, and hAgo4 led to the strongest decrease in miRNA activity, indicating a main role of these proteins. 相似文献
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Nina Hirschhausen Tim Schlesier M. Alexander Schmidt Friedrich Götz Georg Peters Christine Heilmann 《Cellular microbiology》2010,12(12):1746-1764
Staphylococcus aureus and Staphylococcus epidermidis can cause serious chronic and recurrent infections that are difficult to eradicate. An important pathogenicity factor in these infections caused by S. aureus is its ability to be internalized by non‐professional phagocytes thereby evading the host immune system and antibiotic treatment. Here, we report a novel mechanism involved in staphylococcal internalization by host cells, which is mediated by the major autolysin/adhesins Atl and AtlE from S. aureus and S. epidermidis respectively. In a flow cytometric internalization assay, atl and atlE mutants are significantly reduced in their capacities to be internalized by endothelial cells. Moreover, pre‐incubation of endothelial cells with recombinant Atl dose‐dependently inhibited internalization. As putative Atl‐host cell receptor, the heat shock cognate protein Hsc70 was identified by mass spectrometry. The importance of Hsc70 in internalization was demonstrated by the inhibition of S. aureus internalization with anti‐Hsc70 antibodies. In conclusion, this novel Atl‐ or AtlE‐mediated internalization mechanism may represent a ‘back‐up’ mechanism in S. aureus internalization, while it may represent the major or even sole mechanism involved in the internalization of coagulase‐negative staphylococci and thus may play an important role in the pathogenesis of chronic and relapsing infections with these serious pathogens. 相似文献
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Rapid Heteromerization and Phosphorylation of Ligand-activated Plant Transmembrane Receptors and Their Associated Kinase BAK1 总被引:2,自引:0,他引:2
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Sophie Köndgen Svenja Schenk Georg Pauli Christophe Boesch Fabian H. Leendertz 《EcoHealth》2010,7(3):332-341
To diagnose respiratory disease among wild great apes, there is a need for noninvasive diagnostic methods. Therefore, we analyzed fecal samples from habituated chimpanzees from Taï National Park, Côte d’Ivoire. Samples had been collected during four distinct outbreaks: two with known aetiology (March 2004 and February 2006) and two with unknown aetiology (October 2004 and August 2005). Fecal samples were screened by polymerase chain reaction (PCR) for the presence of human metapneumovirus (HMPV) and human respiratory syncytial virus (HRSV), two paramyxoviruses previously found in lung tissue of chimpanzees that died due to respiratory disease. In the March 2004 outbreak, 72% of the tested individuals were positive for HMPV, and during the 2006 epidemic, 25% tested HRSV-positive. In the outbreaks where no causative pathogen was previously known, fecal samples tested positive for either HRSV or HMPV, showing that reinfection occurred. Virus sequences were generated and compared with sequences previously found in tissue; nearly identical virus sequences in both tissue and fecal samples were found. These results demonstrate that fecal samples collected during outbreak times can be used for the diagnostic and phylogenetic analysis of HMPV and HRSV. Using such diagnostic tools, systematic noninvasive disease investigation of respiratory outbreaks in wild great apes becomes possible. The methods presented here may also be applied for the investigation of further acute diseases in great apes and other species. 相似文献
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