1,720,988 research outputs found
Angiogenic-regulatory network revealed by molecular profiling heart tissue following Akt1 induction in endothelial cells
No full textAkt is a pivotal signaling molecule involved in the regulation of angiogenesis. In order to further elucidate the role of Akt1 in blood vessel development, a tetracycline-regulated transgenic system was utilized to conditionally activate Akt1 signaling in endothelial cells to examine transcript expression changes associated with angiogenesis in the heart. Induction of Akt1 over the course of 6 weeks led to a 33% increase in capillary density without affecting overall heart growth. Transcript expression profiles in the hearts were analyzed with an Affymetrix GeneChip Mouse Expression Set 430 2.0, which represents approximately 45,000 cDNAs and ESTs. A total of 248 transcripts were differentially expressed between transgenic and control mice (fold change >/<1.8; false discovery rate < 0.1; P < 0.01). A subset of these differentially expressed transcripts included angiogenic growth factors, cytokines, and extracellular matrix proteins. More specifically, these transcripts included VEGF-receptor2, neuropilin-1, and connective tissue growth factor, each of which is implicated in blood vessel growth and the maintenance of vessel wall integrity. Furthermore, these factors may be involved in an autocrine-regulatory feedback system, one believed to promote vessel growth. Knowledge of these and other targets could be used to treat ischemic heart disease, a disease whose broad spectrum of manifestations range from patients with only effort-induced angina without myocardial damage, through stages of myocardial ischemia that are associated with reversible and irreversible impairment in left ventricular function, to states of irreversible myocardial injury and necrosis resulting in congestive heart failure (CHF). © 2008 Springer Science+Business Media B.V
Validation of new Casein Kinase 1 (CK1) small molecule inhibitor compounds and characterization of Inhibitors of Wnt Production (IWPs) as inhibitors of CK1δ
No full textCasein kinase 1 (CK1) proteins phosphorylate a broad range of substrate proteins and are involved in many physiological processes such as metabolism, transcription, cell cycle progression, apoptosis, and differentiation. The development and characterization of new potent CK1-specific inhibitors might be of interest for new therapeutical concepts in pathological conditions. So far, several CK1 inhibitor compounds have been identified and some of them have already been proven their efficacy in animal models. Still, designing powerful and isoform-specific inhibitors constitutes a challenge. CK1δ inhibition was accomplished in this work through two approaches: the informed design of specific CK1 inhibitors and the repurposing of a well-known small molecule commercially available. The compounds were initially assayed to check for their ability to selectively inhibit CK1 isoforms. Most of the assayed compounds inhibited the activity of CK1δ and CK1ε in a nanomolar range. Compounds 118, 122, 124 and 125 showed the most distinct inhibitory effects. The compounds also showed to act in an ATP-competitive manner. When assayed against a gatekeeper mutant form of CK1δ, the compound did not show differences in inhibitory ability. Compounds 118, 123 and 124 were able to affect cell viability in various tumor cell lines. In the second part of this work, Inhibitors of Wnt Production (IWP) compounds were, for the first time, characterized as CK1δ inhibitors. IWPs share structural similarities with CK1 inhibitors, so it was hypothesized that they could inhibit CK1 isoforms. Commercially-available IWP inhibited the activity of CK1δ/ε. Interestingly, IWPs potently inhibit the gatekeeper mutant CK1δM82F. In vitro and in silico data revealed that IWPs act in an ATP-competitive manner, binding to the kinase’s ATP pocket and establishing interactions with the gatekeeper residue. IWP-2 was assayed in a panel of 321 eukaryotic kinases, revealing a high specificity towards CK1δ. IWP-4 was found to be a powerful inhibitor of cell proliferation in various cancer cell lines. Also, IWP-2 and IWP-2-V2 were used as scaffolds for further drug design, towards improving their ability to inhibit CK1δ. This was partially accomplished with Compound 17, a novel derivative of IWP-2 obtained with the collaboration of our research partners. Compound 17 showed moderately better IC50 values in comparison with its leading compound while retaining its specificity. These results put into a new perspective the use of IWPs in research since they suggest that the direct effects of IWPs on the Wnt pathway are not limited to the inhibition of Porcupine, but also affect pathways directly related to CK1. Studying inhibitor compounds provides new insights into the mechanisms of kinase activity and highlights the potential of small molecule inhibitors for future drug development
Identification of PKCα as a CK1δ C-terminal targeting kinase
No full textCK1 family members are evolutionarily highly conserved in organisms and play crucial roles in the regulation of various cellular processes, including cell cycle, apoptosis, centrosome specific functions, and vesicle transport processes. Because of the pivotal role of CK1 and the dramatic consequences of its deregulation, tight regulatory mechanisms are indispensable to control the activity of CK1 kinase family members. In this thesis, we provide evidence of PKCα (protein kinase C alpha) as another CK1δ C-terminal targeting protein kinase. Furthermore, we show that PKCα is able to phosphorylate CK1δ at residues Ser-318, Ser-328, Thr-329, and Ser-370 within its C-terminal regulatory domain. In addition, the phosphorylation site of Ser-318 seems to have only a minor impact, whereas mutation of Ser-328, Thr-329, and Ser-370 to alanine dramatically alters the kinetic parameters of CK1δ. Additionally, PKCα-mediated phosphorylation down-regulated CK1δ kinase activity in vitro and in COLO357 cells. In summary, our results provide evidence for the regulatory relationship between PKCα and CK1δ, and contribute to a deeper understanding of cellular signal transduction networks
Antiviral Resistance of Splenocytes in Aged Mice
Get PDFWe compared the susceptibility to viral infection of splenocytes, isolated from young versus old CBA mice, and evaluated the antiviral actions of lactoferrin in splenocytes infected with Encephalomyocarditis virus (EMCV). Recombinant mouse lactoferrin (rmLF) and bovine lactoferrin (bLF) were used. There were no differences in the susceptibility to EMCV infection in the studied age categories. Both types of lactoferrins were protective in young and old mice. The study confirmed the undisturbed viral resistance in old mice and the protective actions of lactoferrin in viral infection. The antiviral action of the homologous mouse lactoferrin was demonstrated for the first time
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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