1,720,958 research outputs found
Macroscopic differences in HMGA oncoproteins post-translational modifications:C-terminal phosphorylation of HMGA2 affects its DNA binding properties.
No full textWe have performed an LC/MS screening on several different cell lines to investigate HMGA proteins expression and their posttranslational modifications in order to detect distinctive modification patterns for each. Our analyses evidenced relevant macroscopic differences in the phosphorylation and methylation patterns of these proteins. These differences occur both within the HMGA family members and in the different cell types. Focusing on HMGA2, we have mapped its in vivo phosphorylation sites demonstrating that, similarly to the HMGA1 proteins, it is highly phosphorylated on the acidic C-terminal tail and that these modifications affect its DNA binding properties
HMGA molecular network: From transcriptional regulation tochromatin remodeling
No full textIn the post-genomic era, and with the advent of proteomic tools for the identification of protein-protein interactions, the number of HMGA molecular partners has increased rapidly. This has led to the extension of our knowledge of the functional involvement of HMGA from the transcriptional regulation field to RNA processing, DNA repair, and chromatin remodeling and dynamics. This review focuses mainly on the protein-protein interaction network of HMGA and its functional outcome. HMGA molecular partners have been functionally classified and all the information collected in a freely available database (http://www.bbcm.units.it/∼manfiol/INDEX.HTM)
Interaction proteomics of the HMGA chromatin architectural factors
No full textHere, we report the development of a novel in vitro strategy for the identification of HMGA molecular partners based on the combination of an RP-HPLC prefractionation procedure, 2-DE gels, blot-overlay and MS. To demonstrate that our approach could be a reliable screening method we confirmed a representative number of interactions in vitro by GST pull-down and far-Western and in vivo by co-affinity purification. This approach allowed us to enlarge the HMGA molecular network confirming their involvement also in non-transcriptional-related processes such as RNA processing and DNA repair
Identification and characterization of new molecular partners for the protein arginine methyltransferase 6 (PRMT6)
No full textTo identify in an unbiased manner substrates and potential regulators of PRMT6 we have used a yeast two-hybrid approach. We identified 36 new putative partners for PRMT6 and we validated the interaction in vivo for 7 of them. In addition, using invitro methylation assay we identified 4 new substrates for PRMT6, extending the involvement of this enzyme to other cellular processes beyond its well-established role in gene expression regulation. Holistic approaches create molecular connections that allow to test functional hypotheses. The assembly of PRMT6 protein network allowed us to formulate functional hypotheses which led to the discovery of new molecular partners for the architectural transcription factor HMGA1a, a known substrate for PRMT6, and to provide evidences for a modulatory role of HMGA1a on the methyltransferase activity of PRMT6
PRMT6 : identification and characterization of new molecular partners
Get PDF2008/2009The Protein Arginine Methyltransferase 6 (PRMT6) is an enzyme characterized by a predominant nuclear localization and automethylation activity. Until today, very few information are known about its function and its substrates.
To better characterize PRMT6, we looked for new partners and substrates, using the yeast two-hybrid system. This technique allowed us to discover 36 new partners for this enzyme, 19 of these interactions were confirmed with the GST Pull-down assay. Among these partners, 9 resulted to be interactors also for HMGA protein, a chromatin architectural factor that has been previously demonstrated to be an in vivo substrate of PRMT6. The binding between partners and PRMT6 was further assessed in vivo in mammalian cells, and out of nine proteins tested, 7 were confirmed.
To test whether among the identified partners there were substrates, we performed an in vitro methylation assay, and discovered 4 new substrates of this enzyme (Macrophage migration inhibitory factor, Human DnaJ homologue, Small nuclear ribonucleoprotein-associated proteins B and B’, and Tubulin beta-2A chain). Moreover, we evaluated if the presence of HMGA1a, could modulate the methylation activity of PRMT6. We demonstrated that MIF’s methylation was enhanced in the presence of HMGA1a protein.
Furthermore, to evaluate a possible role played by HMGA, MIF, and PRMT6 together, we studied the effect of MIF on Cyclin A (CycA) promoter. We choose this reporter because it is known the activation effect of HMGA2 protein on this promoter. Our data demonstrated that both MIF and PRMT6 could activate this promoter, but the simultaneous presence of these two proteins result in a lower activation, suggesting that PRMT6 had a negative effect on MIF function.PRMT6 è una Protein Arginine Methyltransferase caratterizzata da una localizzazione prevalentemente nucleare e capacità di autometilazione. Ad oggi, poche informazioni sono note circa la sua funzione ed i suoi substrati.
Per meglio caratterizzare questo enzima, abbiamo cercato nuovi partners e substrati utilizzando il sistema del doppio ibrido in lievito. Questa metodica ci ha permesso di identificare 36 nuovi interattori. Per 19 di questi, l’interazione è stata confermata anche in GST Pull-down, e 9 sono risultati essere partners in comune anche con la proteina HMGA, un fattore architetturale della cromatina che è stato precedentemente dimostrato essere metilato in vivo da PRMT6. Successivamente, per 7 dei 9 interattori testati, il legame con PRMT6 è stato confermato anche in vivo in cellule di mammifero.
Per testare se tra i vari partners identificati ci fossero anche dei substrati, abbiamo effettuato un esperimento di metilazione in vitro che ha portato all’identificazione di 4 nuovi substrati di PRMT6 (Macrophage migration inhibitory factor, Human DnaJ homologue, Small nuclear ribonucleoprotein-associated proteins B and B’, and Tubulin beta-2A chain). Abbiamo inoltre valutato se la presenza di HMGA1a potesse modulare l’attività di metilazione di PRMT6 e abbiamo dimostrato che la metilazione di MIF aumentava in presenza di HMGA1a.
Inoltre, per valutare il possibile ruolo di HMGA, MIF e PRMT6 insieme, abbiamo studiato l’effetto di MIF sul promotore della Ciclina A. E’stato scelto proprio questo promotore in quanto è noto essere attivato della proteina HMGA2. Con i nostri esperimenti abbiamo dimostrato che sia MIF che PRMT6 possono attivarlo, ma la simultanea presenza di queste due proteine risulta in un’attivazione meno forte, suggerendo un effetto negativo per PRMT6 su MIF.XXII Ciclo198
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
- …
