1,720,971 research outputs found
Biochemical and functional characterization of the binding of Neisseria Adhesin A (NadA) with Siglec-5 and 14
Full text linkNeisseria adhesin A (NadA) is a proteic recombinant antigen included in Bexsero, a vaccine against serogroup B Neisseria meningitidis (N. meningitidis). NadA belongs to the trimeric autotransporters family and is composed of a long coiled-coil with three protruding wing-like structures that create an unusual N-terminal head domain. Even though NadA has been extensively described as promoter of both adhesion to and invasion into human epithelial cells, its receptors at the interface with human cells have never been found. To identify the targeted human receptors, we used recombinant NadA (rNadA) as probe on a protein microarray including a expanded collection of surface and secreted human proteins. The screening disclosed three putative interactors, Siglec-5, Siglec-14 and FcγRIIA, expressed on cells of myeloid lineage. We first validated these interactions addressing the biochemical features of the binding, confirming Siglec-5 and -14 as high affinity NadA binding proteins, while FcγRIIA was not. Next, we assessed the membrane properties of NadA binding to Siglecs by using Escherichia coli as an heterologous system. Full-lenght Siglecs, expressed on CHO-K1 cells showed an increase of adhesion of N. meningitidis, whereas the isogenic strain knock-out NadA did not. Although recombinant Siglec-5 ectodomain was shown to bind to NadA on both capsulated and unencapsulated N. meningitidis, we could not find any relevant evidence of NadA/Siglecs interaction on primary and immortalized monocytic cell lines.
In recent years, soluble forms of Siglecs were detected in human serum. In this study, the soluble Siglecs presence was confirmed in human pooled sera and in culture media of monocytes and macrophages. Interestingly, we found that during infection assays N. meningitids was able to bind monocytes-released Siglecs in NadA dependent manner. The exogenous addition of the soluble species increased the attachment of bacteria on monocytic cells surface but reduced internalization.
We also demonstrated a novel interaction between Siglecs and complement component 1 (C1q), whose in vitro interaction was inhibited by recombinant NadA in a concentration dependent manner. Further, we observed a survival advantage for N. meningitidis in presence of bactericidial antibodies anti-NadA by testing sera, as source of complement, depleted of Siglec-5 and -14.
In summary, this work revealed two new human interactors for the neisserial adhesin that could be encountered not only on phagocytes surfaces but also in the bloodstream. On the host side, we characterized a new proteic target for Siglecs on N. meningitidis bacterial surface. Moreover, the C1q binding to Siglec-5 and -14 was revealed for the first time, opening questions on Siglecs biology.
In conclusion we found that NadA may not contribute exclusively to the crossing of the epithelial nasopharyngeal barrier but also it may help the bacterium to survive into extracellular host milieu
MDB-72. BREFELDIN A (BFA) INDUCES CD133 PROTEOLYTIC PROCESSING IN MEDULLOBLASTOMA STEM CELLS (MBSCS)
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Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
MEDB-09. Unraveling the role of unfolded protein response in medulloblastoma cancer stem cells
No full textMedulloblastoma (MB) is the most common malignant childhood brain tumor. The current clinical approach consists of multimodal strategies with debilitating long-term effects and risk of tumor recurrence. Medulloblastoma stem cells (MBSCs) are a fraction of tumor cells with high proliferation potential and the capability to adapt to adverse/restrictive conditions in tumor milieu thus driving the refractoriness to conventional therapies. Recently, high basal levels of Unfolded Protein Response (UPR) molecules have been found in tumors of different tissue-origin and are correlated with poor prognosis and low patient survival. However, little is known about the role of UPR in MB. We investigated the expression and activation of UPR players in MBSCs. Human group 3 MB (G3MB) cell lines, specifically CHLA-01, D283- and D341-Med, were grown in Vitamin A and/or FBS or in stem selective medium (B27™) for 72 h before collection. Cells were fixed, stained with proper primary antibodies and images were acquired by confocal microscopy. The analysis of the transcription factors ATF-4 and CHOP revealed their elevated nuclear expression and co-localization, which resulted to be more marked in G3MB stem-like cells than in the differentiated ones. Also the ATF-6 branch was investigated, in differentiating conditions D283 and D341-Med showed a greater activation of ATF-6, represented by its nuclear localization, in respect to stem cells, while CHLA-01 did not show differences. Conversely XBP1, the transcription factor downstream IRE1 signaling, was not expressed in the three cell lines. Lastly, a Kaplan-Meier analysis on MB patients showed a worse prognosis with a shorter survival rate of patients expressing high ATF4 transcript levels. Our results reveal, even in resting conditions, preferential activation of the PERK branch in G3MB cells grown in stem-like condition suggesting that ATF-4 might be a promising therapeutic and prognostic factor to specifically target the stem compartment in aggressive MB
Different chronic stress paradigms converge on endogenous TDP43 cleavage and aggregation
Full text linkThe TAR-DNA binding protein (TDP43) is a nuclear protein whose cytoplasmic inclusions are hallmarks of Amyotrophic Lateral Sclerosis (ALS). Acute stress in cells causes TDP43 mobilization to the cytoplasm and its aggregation through different routes. Although acute stress elicits a strong phenotype, is far from recapitulating the years-long aggregation process. We applied different chronic stress protocols and described TDP43 aggregation in a human neuroblastoma cell line by combining solubility assays, thioflavin-based microscopy and flow cytometry. This approach allowed us to detect, for the first time to our knowledge in vitro, the formation of 25 kDa C-terminal fragment of TDP43, a pathogenic hallmark of ALS. Our results indicate that chronic stress, compared to the more common acute stress paradigm, better recapitulates the cell biology of TDP43 proteinopathies. Moreover, we optimized a protocol for the detection of bona fide prions in living cells, suggesting that TDP43 may form amyloids as a stress response
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Analogies and Differences Between Dental Stem Cells: Focus on Secretome in Combination with Scaffolds in Neurological Disorders
Full text linkMesenchymal stem cells (MSCs) are well known for their beneficial effects, differentiation capacity and regenerative potential. Dental-derived MSCs (DSCs) are more easily accessible and have a non-invasive isolation method rather than MSCs isolated from other sources (umbilical cord, bone marrow, and adipose tissue). In addition, DSCs appear to have a relevant neuro-regenerative potential due to their neural crest origin. However, it is now known that the beneficial effects of MSCs depend, at least in part, on their secretome, referring to all the bioactive molecules (neurotrophic factors) released in the conditioned medium (CM) or in the extracellular vesicles (EVs) in particular exosomes (Exos). In this review, we described the similarities and differences between various DSCs. Our focus was on the secretome of DSCs and their applications in cell therapy for neurological disorders. For neuro-regenerative purposes, the secretome of different DSCs has been tested. Among these, the secretome of dental pulp stem cells and stem cells from human exfoliated deciduous teeth have been the most widely studied. Both CM and Exos obtained from DSCs have been shown to promote neurite outgrowth and neuroprotective effects as well as their combination with scaffold materials (to improve their functional integration in the tissue). For these reasons, the secretome obtained from DSCs in combination with scaffold materials may represent a promising tissue engineering approach for neuroprotective and neuro-regenerative treatments
The endocrine disruptor cadmium modulates the androgen-estrogen receptors ratio and induces inflammatory cytokines in luminal (A) cell models of breast cancer
Full text linkPurpose: Breast cancer (BC) is the most common malignancy that affects women, and it is, to date, their leading cause of death. Luminal A molecular subtype accounts for 40% of BC and is characterized by hormone receptors positive/human epidermal growth factor 2 expression and current treatment consists of surgery plus aromatase inhibitor therapy. Interestingly, several studies demonstrated that the heavy metal cadmium (Cd), classified as a group 1 human carcinogen and widely spread in the environment, exerts estrogen-like activities in several tissues and suggested an intriguing relationship between increased Cd exposure and BC incidence. Thus, aim of this study was to evaluate effects of Cd on Luminal A BC estrogen receptor (ER) positive/progesterone receptor positive cell models in vitro to characterize the mechanism(s) involved in breast cell homeostasis disruption. Methods: T47D and MCF7 were exposed to Cd (0.5-1 μM) for 6-24 h to evaluate potential alterations in: cells viability, steroid receptors and intracellular signaling by western blot. Moreover, we evaluated the expression of inflammatory cytokines interleukin by RT-PCR. Results: Our results showed a significant induction of androgen receptor (AR) and an increased AR/ER ratio. Further, Cd exposure increased pro-inflammatory cytokines interleukin (IL)6, IL8 and tumor necrosis factor α levels. Finally, as previously demonstrated by our group, Cd alters pathways such as mitogen-activated protein kinase family and protein kinase B. Conclusion: In conclusion, our study demonstrates that Cd modifies the expression and pattern of ERs and AR in BC cell lines, suggesting an alteration of BC cells homeostasis, likely predisposing to a carcinogenetic microenvironment
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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