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Novel mechanisms regulating CCRL2 expression and function
Full text linkCCRL2 is a seven transmembrane domain receptor, structurally and
functionally related to the atypical chemokine receptors family. However, the
only recognized ligand for this receptor is the chemotactic protein chemerin.
To date, two main functions were described to be associated to CCRL2. The first
one is to act as presenting molecule when expressed on the surface of
epithelial barrier cells, where it can concentrate chemerin, thus creating a
membrane-bound chemerin gradient able to regulate the migration of
adjacent leukocytes expressing the chemerin functional receptor Chemerin1.
On the other hand, CCRL2 has been shown to regulate leukocytes migration
through the interaction with conventional chemokine receptors. Indeed, by
forming heterodimers, CCRL2 can regulate the functionality of the prototypical
neutrophil chemokine receptor CXCR2. CCRL2 functionality was also
investigated in-vivo in models of inflammatory diseases and carcinogenesis,
providing important insights of its role in different pathological conditions.
Part I
Recently, a novel possible function for CCRL2 was described: the interaction
with TLR4. This interaction is functional to induce the retention of TLR4 on the
plasma membrane of tumor associated macrophages, thus promoting the
maintenance of a pro-inflammatory TLR4-mediated signaling, preventing the
switch towards a M2-like anti-inflammatory phenotype. Thus, TAMs could
retain a pro-inflammatory anti-tumoral M1-like phenotype.
The first part of this thesis will elucidate the functional relationship between
CCRL2 and other TLRs, specifically TLR7. The functional interaction between
CCRL2 and TLR7 was investigated by using an in vitro model of bone-marrow
derived dendritic cells (BMDCs) generated by CD34+ hematopoietic bone
marrow precursors, obtained from WT and CCRL2 knockout (KO) mice. We
focused our attention on dendritic cells (DCs) as they are the main antigen
presenting cells, playing a crucial role in bridging innate and adaptive immune
responses. WT and CCRL2 KO BMDCs were then stimulated with TLR7 agonist
R848, with the purpose of performing a phenotypical and functional
characterization. Our results displayed an impaired secretion of pro-
inflammatory cytokines in CCRL2 KO DCs after TLR7 triggering, suggesting
CCRL2 may be involved in the regulation of TLR7 mediated pro-inflammatory
signaling. Moreover, on the one hand, flow cytometry experiments showed
that the impaired pro-inflammatory secretion was not due to a defective
maturation of CCRL2 KO cells. On the other hand, qPCR and Western Blot
experiments demonstrated that CCRL2 does not affect TLR7 expression. Thus,
given the crucial role of NF-κB in the production of pro-inflammatory cytokines,
NF-κB translocation to the nucleus was assessed via Western Blot. The
translocation of NF-κB to the nucleus was found impaired in CCRL2 KO BMDCs
compared to WT BMDCs. These results suggest CCRL2 may play a crucial role
in the NF-κB phosphorylation, thus impairing the pro-inflammatory response
in DCs and affecting the secretion of pro-inflammatory cytokines in the
supernatant.
Part II
Colorectal cancer (CRC) is the fourth most deadly and the third most common
cancer worldwide with approximately 900’000 diagnosis per year, accounting
around 10% of cancer-related deaths worldwide. Despite the role of CCRL2 in
carcinogenesis is still under investigation, in a murine model of lung cancer it
was demonstrated that its ablation reduced the recruitment of several myeloid
cells subsets and NK cells in the tumor microenvironment, thus positioning
CCRL2 as a tumor-suppressor gene. Inflammation represents one of the key
drivers of CRC and preliminary data, generated in our laboratory, related to
AOM/DSS murine model of inflammation-associated carcinogenesis, have
shown that CCRL2 KO mice are more susceptible to the development of
intestinal polyps in comparison to WT control animals. Moreover, previous
results suggest a correlation between low CCRL2 expression and poorer
survival rate in patients. Taken together, these findings suggest that CCRL2 may
play a role as a novel tumor-suppressing gene, whose silencing promotes
carcinogenesis.
One of the most relevant mechanisms of tumor-suppressor gene silencing is
represented by DNA methylation. On this basis the aim of the second part of
this thesis was to investigate CCRL2 methylation-mediated silencing in CRC. The
model in which we decided to investigate CCRL2 methylation in CRC were
human CRC cell lines that expressed (RKO) or did not express (SW480) CCRL2.
The level of methylation of CCRL2 was investigated by two different
approaches: an indirect method consisting in the treatment with a
demethylating agent, 5’-Aza-2’-deoxicytidine (5-AZA-dC) and a direct method
based on the immunoprecipitation of methylated DNA (MeDIP). Our results
showed high levels of methylated DNA in the transcription factors binding site
(TFBS) region of CCRL2 putative promoter in SW480 cells. In contrast, RKO cells,
which were found to express CCRL2 in normal conditions, showed low levels of
methylated DNA in the TFBS region. In fact, the treatment with 5-AZA-dC, led
to an increase of CCRL2 expression in SW480 cells, but not in RKO cells.
Moreover, we set the basis for the analysis of histone modifications in CCRL2
TFBS region by chromatin immunoprecipitation (ChIP), targeting the tri-
methylated fourth lysine residue of H3 histone (H3K4me3), a modification
associated to transcriptional activation. In accordance with the results
obtained by MeDIP, SW480 cells showed lower levels of H3K4me3 compared
to RKO cells. Thus, our results support the hypothesis of CCRL2 epigenetic
silencing in the context of CRC and lay the foundation to investigate the role of
CCRL2 as a novel tumor-suppressor gene
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
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
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
Local administration of interleukin-2 activates lymphocytes from tumor bearing mice to recruit host immunoreactivity and inhibit tumor growth.
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Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Leishmania major: Infection of human monocytes selectively induces production of chemokines.
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