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Signaling-mediated control of ubiquitin ligases in endocytosis
Simona Polo
BMC Biology , 2012, DOI: 10.1186/1741-7007-10-25
Abstract: Ubiquitination modifies proteins in a variety of ways, the significance of which we only partially comprehend. Ubiquitin can be attached: as an individual moiety to a single or multiple lysine residues of substrate (mono- or multiple monoubiquitination); as chains of ubiquitin moieties that are interlinked through any one of the seven lysine residues of ubiquitin (for example K48- or K63-linked chains); or as branched chains, to name but a few [1]. The cell interprets each of these modifications as a distinct signal. The first described role of ubiquitination as mediating protein degradation through targeting to the proteasome has now been complemented with numerous other functions [2]. For example, the signal encoded by K63-linked chains can mediate functions as diverse as receptor endocytosis [3,4], activation of protein kinases in the NF-κB pathway and the initiation of error-free DNA repair [2].Signal transduction from transmembrane cell surface receptors to nuclear transcription factors is regulated at multiple levels by protein ubiquitination. The covalent attachment of one, or often more, ubiquitin moieties has emerged as the principal mechanism for termination of signaling, by targeting the receptor for endocytosis and, ultimately, degradation in the lysosome [3]. This device controls a vast array of mammalian signaling receptors, such as receptor tyrosine kinases, G-protein coupled receptors (GPCRs), growth hormone receptors, the major histocompatibility complex I, NOTCH, various channels and transporters, and cytokine and interferon receptors [3]. Receptors that are internalized after activation are directed first into the endosomes of the endocytic pathway, and then into multivesicular bodies (MVBs), which undergo a process of maturation that ends with fusion with the lysosome and delivery of the contents for degradation. Ubiquitination of the receptor provides the crucial signal for entering this pathway [3,5-7].Subsequent delivery of membrane receptors
The ubiquitination code: a signalling problem
Tanja Woelk, Sara Sigismund, Lorenza Penengo, Simona Polo
Cell Division , 2007, DOI: 10.1186/1747-1028-2-11
Abstract: Cells use a system of post-translational protein modifications to generate and transmit signals in almost every pathway. One of them is ubiquitination. When appended to target proteins ubiquitin (Ub) can affect their localization, activity, structure and interaction partners. Similarly to the phospho-based signal, the ubiquitin signal is recognized by specific domains (Ubiquitin Binding Domains, UBDs), carried by proteins (Ub receptors) that represent signal transducers. More parallels can be drawn with phosphorylation: ubiquitination is reversible thanks to deubiquitinating enzymes (DUBs) and it is inducible by various stimuli. Compared to phosphorylation, the signal generated by the 76-residue Ub protein is certainly more complex. Ub can be appended as a monomer or as isopeptide-linked polymers named polyubiquitin chains. The existence of a vast array of Ub signals raises the question of how the specificity of signal recognition might be achieved. Indeed, the molecular requirements for recognition of the various known Ub signals are poorly understood and form a central question in the field.Here, we will discuss recent studies that shed new light on the Ub code and that regard the topology of Ub signals, the identification of new UBDs and the regulation of the critical enzymes of the signalling cascade, namely, the E3 ligases.Substrate proteins can be modified by Ub in different ways (Figure 1). Monoubiquitination is the attachment of one Ub moiety to a single lysine residue. This modification is a reversible, non-proteolytic signal involved in endocytosis, endosomal sorting, histone regulation, DNA repair, virus budding and nuclear export (reviewed in [1-4]). A variation of this theme occurs when several lysine residues of a substrate are modified by a single Ub molecule, giving rise to multiple monoubiquitination that plays a role in receptor internalization and endocytosis [5-7].Ubiquitin itself contains seven lysine residues that can be potentially used as acc
Perinatal outcomes among immigrant mothers over two periods in a region of central Italy
Laura Cacciani, Simona Asole, Arianna Polo, Francesco Franco, Renato Lucchini, Mario De Curtis, Domenico Di Lallo, Gabriella Guasticchi
BMC Public Health , 2011, DOI: 10.1186/1471-2458-11-294
Abstract: The source of this area-based study was the regional hospital discharge database that records perinatal information on all births in the Lazio region. We analysed 296,739 singleton births born between 1996-1998 and 2006-2008. The exposure variable was the mother's region of birth. We considered five outcomes of perinatal health. We estimated crude and adjusted odds ratios and 95% confidence intervals (CIs) to evaluate the association between mother's region of birth and perinatal outcomes.Perinatal outcomes were worse among infants of immigrant compared to Italian mothers, especially for sub-Saharan and west Africans, with the following crude ORs (in 1996-1998 and 2006-2008 respectively): 1.80 (95%CI:1.44-2.28) and 1.95 (95%CI:1.72-2.21) for very preterm births, and 1.32 (95%CI:1.16-1.50) and 1.32 (95%CI:1.25-1.39) for preterm births; 1.18 (95%CI:0.99-1.40) and 1.17 (95%CI:1.03-1.34) for a low Apgar score; 1.22 (95%CI:1.15-1.31) and 1.24 (95%CI:1.17-1.32) for the presence of respiratory diseases; 1.47 (95%CI:1.30-1.66) and 1.45 (95%CI:1.34-1.57) for the need for special or intensive neonatal care/in-hospital deaths; and 1.03 (95%CI:0.93-1.15) and 1.07 (95%CI:1.00-1.15) for congenital malformations. Overall, time did not affect the odds of outcomes differently between immigrant and Italian mothers and most outcomes improved over time among all infants. None of the risk factors considered confounded the associations.Our findings suggest that migrant status is a risk factor for adverse perinatal health. Moreover, they suggest that perinatal outcomes improved over time in some immigrant women. This could be due to a general improvement in immigrants' health in the past decade, or it may indicate successful application of policies that increase accessibility to mother-child health services during the periconception and prenatal periods for legal and illegal immigrant women in Italy.Immigration in Italy is an important and widespread phenomenon. The number of immigrants l
El DENEPER: Una Metodología para Detectar Necesidades de Perfeccionamiento Docente
POLO,Marina;
Revista de Pedagogía , 2003,
Abstract: here, a teacher training needs analysis model designed for university professors is presented. the issue of university transformation is addressed from the point of view of training, updating and improvement of the teaching staff. in this sense, the analysis is made by acknowledging the existing gaps between what instructors actually do and what they are expected to be doing. the deneper method is characterized by the use of shared knowledge about the strengths and weaknesses present in the teaching profession and which in turn are ?problematized? in order to turn personal insights into dialogic communicative acts. with this frame of mind, we move forward from traditional needs analysis into teacher perfecting on the basis of using teacher previous insights to gain knowledge about what they need to know or experience in their normal activities. the model is based on nine steps: it tries to structure comprehension of the pedagogical process in order to produce reflexive teaching practices and to come up with a teacher training program designed on certain shared principles. the model has been put into practice in the teacher updating system of our university (sadpro), a process in which a group of staff members from various institutions of higher learning have been participating.
Investigar en Africa
Vallejo, Polo
Revista de la Lista Electrónica Europea de Música en la Educación , 2000,
Abstract:
Synchronic and diachronic variation phenomena in inverted interrogative and related contexts in Northern Italian dialects
Chiara Polo
Nordlyd : Troms? University Working Papers on Language & Linguistics / Institutt for Spr?k og Litteratur, Universitetet i Troms? , 2007,
Abstract: In the spirit of Ferdinand de Saussure, the present contribution is offered as an integrated synchronic and diachronic analysis of syntactic variation phenomena across a selected number of Veneto and other Northern Italian dialects: the main focus of the study will be on (unembedded) interrogative clauses. The goal targeted is to account for the wide range of structural options allowed by contemporary dialects (VS/SV/SVS) in the light of the discrepant evolutionary stages they embody and reflect, as independently reconstructed and singled out in the history of the Venetian dialect. Seemingly idiosyncratic contemporary inter-dialectal variation phenomena are thus viewed as functions of the different parametric values dialects activate in dependence on the position they occupy in an evolutionary continuum which promotes the elimination of an anciently fully productive inverted pattern VS (along with the syntactic rule V-to-C which possibly underlies its generation).
Image fusion techniques in permanent seed implantation
Alfredo Polo
Journal of Contemporary Brachytherapy , 2010,
Abstract: Over the last twenty years major software and hardware developments in brachytherapy treatment planning, intraoperative navigation and dose delivery have been made. Image-guided brachytherapy has emerged as the ultimate conformal radiation therapy, allowing precise dose deposition on small volumes under direct image visualization. In thisprocess imaging plays a central role and novel imaging techniques are being developed (PET, MRI-MRS and power Doppler US imaging are among them), creating a new paradigm (dose-guided brachytherapy), where imaging is used to map the exact coordinates of the tumour cells, and to guide applicator insertion to the correct position. Each of these modalities has limitations providing all of the physical and geometric information required for the brachytherapy workflow.Therefore, image fusion can be used as a solution in order to take full advantage of the information from each modality in treatment planning, intraoperative navigation, dose delivery, verification and follow-up of interstitial irradiation.Image fusion, understood as the visualization of any morphological volume (i.e. US, CT, MRI) together with an additional second morpholo gical volume (i.e. CT, MRI) or functional dataset (functional MRI, SPECT, PET), is a well known method for treatment planning, verification and follow-up of interstitial irradiation. The term image fusion is used when multiple patient image datasets are registered and overlaid or merged to provide additional information. Fused images may be created from multiple images from the same imaging modality taken at different moments (multi-temporalapproach), or by combining information from multiple modalities. Quality means that the fused images should provide additional information to the brachythe rapy process (diagnosis and staging, treatment planning, intraoperative imaging, treatment delivery and follow-up) that cannot be obtained in other ways. In this review I will focus on the role of image fusion for permanent seed implantation.
Sensitive dependence on initial conditions and chaotic group actions
Fabrizio Polo
Mathematics , 2009,
Abstract: A continuous action of a group G on a compact metric space has sensitive dependence on initial conditions if there is a number e>0 such that for any open set U we can find g in G such that g.U has diameter greater than e. We prove that if a G action preserves a probability measure of full support, then the system is either minimal and equicontinuous, or has sensitive dependence on initial conditions. This generalizes the invertible case of a theorem of Glasner and Weiss. We prove that when a finitely generated, solvable group, acts and certain cyclic subactions have dense sets of minimal points, then the system has sensitive dependence on initial conditions. Additionally, we show how to construct examples of non-compact monothetic groups, and transitive, non-minimal, almost-equicontinuous, recurrent, group actions.
Segmenti paralleli
Antonio Polo
Mathematics , 2011,
Abstract: In this article (it's only in italian, but I'm translating it) I will try to solve some questions about a mathematical problem that my friend Patrizio Frederic, a researcher in statistics at the University of Modena, proposed to me. Given some parallel line segments, is there at least one straight line that passes through all of them? If there were many lines that solve the problem, how can I choose a "better one" among all of them? I fully answer the first question, for the second I'll just give some ideas for future research.
Parallel line segments
Antonio Polo
Mathematics , 2011,
Abstract: In this article I will address some questions about a mathematical problem that my friend Patrizio Frederic, a researcher in statistics at the University of Modena, proposed to me. Given some parallel line segments, is there at least one straight line that passes through all of them? If there were many lines that solve the problem, can I choose a "best one" among all of them? I will fully address the first question. As for the second question, I will illustrate it with some "experimental" examples and suggest an outline for future explorations.
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