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991.
Nina Bertaux-Skeirik Rui Feng Michael A. Schumacher Jing Li Maxime M. Mahe Amy C. Engevik Jose E. Javier Richard M. Peek Jr Karen Ottemann Veronique Orian-Rousseau Gregory P. Boivin Michael A. Helmrath Yana Zavros 《PLoS pathogens》2015,11(2)
The cytotoxin-associated gene (Cag) pathogenicity island is a strain-specific
constituent of Helicobacter pylori (H. pylori) that
augments cancer risk. CagA translocates into the cytoplasm where it stimulates cell
signaling through the interaction with tyrosine kinase c-Met receptor, leading
cellular proliferation. Identified as a potential gastric stem cell marker,
cluster-of-differentiation (CD) CD44 also acts as a co-receptor for c-Met, but
whether it plays a functional role in H. pylori-induced epithelial
proliferation is unknown. We tested the hypothesis that CD44 plays a functional role
in H. pylori-induced epithelial cell proliferation. To assay changes
in gastric epithelial cell proliferation in relation to the direct interaction with
H. pylori, human- and mouse-derived gastric organoids were
infected with the G27 H. pylori strain or a mutant G27 strain
bearing cagA deletion (∆CagA::cat). Epithelial proliferation
was quantified by EdU immunostaining. Phosphorylation of c-Met was analyzed by
immunoprecipitation followed by Western blot analysis for expression of CD44 and
CagA. H. pylori infection of both mouse- and human-derived gastric
organoids induced epithelial proliferation that correlated with c-Met
phosphorylation. CagA and CD44 co-immunoprecipitated with phosphorylated c-Met. The
formation of this complex did not occur in organoids infected with
∆CagA::cat. Epithelial proliferation in response to
H. pylori infection was lost in infected organoids derived from
CD44-deficient mouse stomachs. Human-derived fundic gastric organoids exhibited an
induction in proliferation when infected with H. pylorithat was not
seen in organoids pre-treated with a peptide inhibitor specific to CD44. In the
well-established Mongolian gerbil model of gastric cancer, animals treated with CD44
peptide inhibitor Pep1, resulted in the inhibition of H.
pylori-induced proliferation and associated atrophic gastritis. The current
study reports a unique approach to study H. pylori interaction with
the human gastric epithelium. Here, we show that CD44 plays a functional role in
H. pylori-induced epithelial cell proliferation. 相似文献
992.
993.
994.
Sarah Willkomm Andrea Deerberg Johannes Heidemann Friedemann Flügge Janica Meine Rui Hu Rosel Kretschmer-Kazemi Far Tobias Restle 《PloS one》2016,11(1)
The human TAR RNA-binding protein (hTRBP) and protein activator of protein kinase R (hPACT) are important players in RNA interference (RNAi). Together with hArgonaute2 (hAgo2) and hDicer they have been reported to form the RISC-loading complex (RLC). Among other functions, hTRBP was suggested to assist the loading of hAgo2 with small interfering RNAs (siRNAs) within the RLC. Although several studies have been conducted to evaluate the specific functions of hTRBP and hPACT in RNAi, exact mechanisms and modes of action are still unknown. Here, we present a biochemical study further evaluating the role of hTRBP and hPACT in hAgo2-loading. We found that both proteins enhance hAgo2-mediated RNA cleavage significantly; even a hAgo2 mutant impaired in siRNA binding shows full cleavage activity in the presence of hTRBP or hPACT. Pre-steady state binding studies reveal that the assembly of wildtype-hAgo2 (wt-hAgo2) and siRNAs remains largely unaffected, whereas the binding of mutant hAgo2-PAZ9 to siRNA is restored by adding either hTRBP or hPACT. We conclude that both proteins assist in positioning the siRNA within hAgo2 to ensure optimal binding and cleavage. Overall, our data indicate that hTRBP and hPACT are part of a regulative system of RNAi that is important for efficient target RNA cleavage. 相似文献
995.
996.
This experiment was designed to investigate whether chronic hypoxia affect rat pulmonary artery (PA) endothelium-dependent relaxation and the content of cGMP in PA. Both ACh and ATP could induce endothelium-dependent relaxation of PA, not prevented by indomethacin, but completely abolished by methylene blue. These results indicated that vasodilatation of PA induced by both ACh and ATP is mediated by EDRF (endothelium-derived relaxing factor). Chronic hypoxia significantly depressed PA endothelium-dependent relaxation. The percent relaxation of IPPA and EPPA by 10(-6) mol/L ACh was 61.3% and 59.2% of those in control, and the percent relaxation of IPPA and EPPA by 1.8 x 10(-5) mol/L ATP was 64.9% and 55.3% respectively of the control. Chronic hypoxia also depressed SNP-induced endothelium-independent relaxation. Chronic hypoxia significantly decreased the content of cGMP in PA. The basic level of cGMP was 51.9 +/- 5.7 (n = 14) in hypoxia group and 84.9 +/- 9.7 (n = 14) pmol/g wet wt. in control group (P less than 0.01). After treatment of PA with ACh (10(-7) mol/L), the content of cGMP was 91.4 +/- 7.3 (n = 5) pmol/g wet wt. in hypoxic group and 240.8 +/- 30.6 (n = 5) pmol/g wet wt. in control group (P less than 0.01). Our data suggest that chronic hypoxia might depress rat pulmonary artery endothelium-dependent relaxation through the inhibition of soluble guanylate cyclase in vascular smooth muscle cells. 相似文献
997.
Yipeng Cao Rui Yang Imshik Lee Wenwen Zhang Jiana Sun Wei Wang Xiangfei Meng 《Protein science : a publication of the Protein Society》2021,30(6):1114
The COVID‐19 epidemic is one of the most influential epidemics in history. Understanding the impact of coronaviruses (CoVs) on host cells is very important for disease treatment. The SARS‐CoV‐2 envelope (E) protein is a small structural protein involved in many aspects of the viral life cycle. The E protein promotes the packaging and reproduction of the virus, and deletion of this protein weakens or even abolishes the virulence. This review aims to establish new knowledge by combining recent advances in the study of the SARS‐CoV‐2 E protein and by comparing it with the SARS‐CoV E protein. The E protein amino acid sequence, structure, self‐assembly characteristics, viroporin mechanisms and inhibitors are summarized and analyzed herein. Although the mechanisms of the SARS‐CoV‐2 and SARS‐CoV E proteins are similar in many respects, specific studies on the SARS‐CoV‐2 E protein, for both monomers and oligomers, are still lacking. A comprehensive understanding of this protein should prompt further studies on the design and characterization of effective targeted therapeutic measures. 相似文献
998.
999.
Lingling Gao Xin Nie Rui Gou Yuexin Hu Hui Dong Xiao Li Bei Lin 《Journal of cellular and molecular medicine》2021,25(23):10916-10929
Ovarian cancer, one of the malignant gynaecological tumours with the highest mortality rate among female reproductive system, is prone to metastasis, recurrence and chemotherapy resistance, causing a poor prognosis. Exosomes can regulate the epithelial-mesenchymal plasticity of tumour cells, remodel surrounding tumour microenvironment, and affect tumour cell proliferation, invasion and metastasis. However, the function and mechanism of exosomes in the intraperitoneal implantation of ovarian cancer remain unclear. In this study, exosomal annexin A2 (ANXA2) derived from ovarian cancer cells was co-cultured with human peritoneal mesothelial (HMrSV5) cells; functional experiments were conducted to explore the effects of exosomal ANXA2 on the biological behaviour of HMrSV5 and the related mechanisms. This study showed that ANXA2 in ovarian cancer cells can be transferred to HMrSV5 cells through exosomes, exosomal ANXA2 can not only promote the migration, invasion and apoptosis of HMrSV5 cells, but also regulates morphological changes and fibrosis of HMrSV5 cells. Furthermore, ANXA2 promotes the mesothelial-mesenchymal transition (MMT) and degradation of the extracellular matrix of HMrSV5 cells through PI3K/AKT/mTOR pathway, finally affects pre-metastasis microenvironment of ovarian cancer, which provides a new theoretical basis for the mechanism of intraperitoneal implantation and metastasis of ovarian cancer. 相似文献
1000.
Potential natural vegetation and pre‐anthropic pollen records on the Azores Islands in a Macaronesian context 下载免费PDF全文
This paper discusses the concept of potential natural vegetation (PNV) in the light of the pollen records available to date for the Macaronesian biogeographical region, with emphasis on the Azores Islands. The classical debate on the convenience or not of the PNV concept has been recently revived in the Canary Islands, where pollen records of pre‐anthropic vegetation seemed to strongly disagree with the existing PNV reconstructions. Contrastingly, more recent PNV model outputs from the Azores Islands show outstanding parallelisms with pre‐anthropic pollen records, at least in qualitative terms. We suggest the development of more detailed quantitative studies to compare these methodologies as an opportunity for improving the performance of both. PNV modelling may benefit by incorporating empirical data on past vegetation useful for calibration and validation purposes, whereas palynology may improve past reconstructions by minimizing interpretative biases linked to differential pollen production, dispersal and preservation. 相似文献