Linking pseudouridine synthases to growth, developmentand cell competition

Eukaryotic pseudouridine synthases direct RNA pseudouridylation and bind H⁄ACA small nucleolar RNA (snoRNAs), which, in turn, may act as precursors of microRNA-like molecules. In humans, loss of pseudouridine synthase activity causes dyskeratosis congenita (DC), a complex systemic disorder characterized by cancer susceptibility, failures in ribosome biogenesis and telomere stability, and defects in stem cell formation. Considering the significant interest in deciphering the various molecular consequences of pseudouridine synthase failure, we performed a loss of function analysis of minifly (mfl), the pseudouridine synthase gene of Drosophila, in the wing disc, an advantageous model system for studies of cell growth and differentiation. In this organ, depletion of the mfl-encoded pseudouridine synthase causes a severe reduction in size by decreasing both the number and the size of wing cells. Reduction of cell number was mainly attributable to cell death rather than reduced proliferation, establishing that apoptosis plays a key role in the development of the loss of function mutant phenotype. Depletion of Mfl also causes a proliferative disadvantage in mosaic tissues that leads to the elimination of mutant cells by cell competition. Intriguingly, mfl silencing also triggered unexpected effects on wing patterning and cell differentiation, including deviations from normal lineage boundaries, mingling of cells of different compartments, and defects in the formation of the wing margin that closely mimic the phenotype of reduced Notch activity. These results suggest that a component of the pseudouridine synthase loss of function phenotype is caused by defects in Notch signalling

The coding/non-coding overlapping architecture of the gene encoding the Drosophila pseudouridine synthase

BACKGROUND: In eukaryotic cells, each molecule of H/ACA small nucleolar RNA (snoRNA) assembles with four evolutionarily conserved core proteins to compose a specific ribonucleoprotein particle. One of the four core components has pseudouridine synthase activity and catalyzes the conversion of a selected uridine to pseudouridine. Members of the pseudouridine synthase family are highly conserved. In addition to catalyzing pseudouridylation of target RNAs, they carry out a variety of essential functions related to ribosome biogenesis and, in mammals, to telomere maintenance. To investigate further the molecular mechanisms underlying the expression of pseudouridine synthase genes, we analyzed the transcriptional activity of the Drosophila member of this family in great detail. RESULTS: The Drosophila gene for pseudouridine synthase, minifly/Nop60b (mfl), encodes two novel mRNAs ending at a downstream poly(A) site. One species is characterized only by an extended 3'-untranslated region (3'UTR), while a minor mRNA encodes a variant protein that represents the first example of an alternative subform described for any member of the family to date. The rare spliced variant is detected mainly in females and is predicted to have distinct functional properties. We also report that a cluster comprising four isoforms of a C/D box snoRNA and two highly related copies of a small ncRNA gene of unknown function is intron-encoded at the gene-variable 3'UTRs. Because this arrangement, the alternative 3' ends allow mfl not only to produce two distinct protein subforms, but also to release different ncRNAs. Intriguingly, accumulation of all these intron-encoded RNAs was found to be sex-biased and quantitatively modulated throughout development and, within the ovaries, the ncRNAs of unknown function were found not ubiquitously expressed. CONCLUSION: Our results expand the repertoire of coding/non-coding transcripts derived from the gene encoding Drosophila pseudouridine synthase. This gene exhibits a complex and interlaced organization, and its genetic information may be expressed as different protein subforms and/or ncRNAs that may potentially contribute to its biological functions

Differential subcellular recruitment of monoacylglycerol lipase generates spatial specificity of 2-arachidonoyl glycerol signaling during axonal pathfinding

Peer reviewedPublisher PD

Combined effect of obesity and diabetes on early breast cancer outcome: A prospective observational study

Background: Previous studies suggested that obesity and diabetes were correlated with breast cancer outcome. The aim of the present study was to investigate the prognostic effect of obesity and diabetes on the outcome of early breast cancer patients. Materials and Methods: Overall, 841 early breast cancer patients were prospectively enrolled between January 2009 and December 2013. Study population was divided into four groups: (1) patients without obesity or diabetes; (2) patients with only diabetes; (3) patients with only obesity; and (4) patients with both diabetes and obesity. Categorical variables were analyzed by the chi-square test and survival data by the log-rank test. Results: At diagnosis, obese and diabetic patients were more likely to be older (p < 0.0001) and post-menopausal (p < 0.0001) and to have a tumor larger than 2 cm (p < 0.0001) than patients in groups 1–3. At univariate analyses, obese and diabetic patients had a worse disease-free survival (p = 0.01) and overall survival (p = 0.001) than did patients without obesity and diabetes. At multivariate analyses, the co-presence of obesity and diabetes was an independent prognostic factor for diseasefree survival (hazard ratio=2.62, 95% CI 1.23–5.60) but not for overall survival. Conclusions: At diagnosis, patients with obesity and diabetes were older, had larger tumors and a worse outcome compared to patients without obesity or diabetes. These data suggest that metabolic health influences the prognosis of patients affected by early breast cance

Prevention of Recurrent Benign Paroxysmal Positional Vertigo: The Role of Combined Supplementation with Vitamin D and Antioxidants

Benign paroxysmal positional vertigo (BPPV) usually has a favorable course, although it is possible to observe BPPV with a high recurrence rate. Previous studies suggested that vitamin D deficiency might affect BPPV recurrences, and oxidative stress might play a complementary role in BPPV pathogenesis. This multicentric trial aimed to evaluate the effectiveness of oral nutritional supplementation with a compound of alpha-lipoic acid, Carnosine, and Zinc (LICA (R) (Difass International, Coriano (RN), Italy)), vitamins of group B and vitamin D in preventing BPPV recurrences. A total of 128 patients with high recurrence-BPPV were randomized in three arms: Arm 1 consisted of subjects with "insufficient" or "deficient" vitamin D blood levels, treated with daily oral supplementation of LICA (R), vitamins of group B and vitamin D3 (800 UI), Arm 2 included BPPV subjects with "sufficient" vitamin D who did not receive any nutritional support, and Arm 3 included subjects with a "sufficient" serum concentration of vitamin D who received supplementation with a compound of LICA (R) and Curcumin. After six months of follow-up, a significant reduction of BPPV relapses compared to the baseline was found only in Arm 1 (-2.32, 95% CI: 3.41-1.62, p-value &lt; 0.0001). Study results suggested that oral nutritional supplementation with vitamin D3 plus antioxidants can prevent relapses in patients suffering from high recurrence-BPPV

“Ruolo del gene minifly nello sviluppo di Drosophila melanogaster”

Il progetto di ricerca sviluppato nel corso della mia tesi di dottorato è stato centrato sulla caratterizzazione molecolare e funzionale del gene minifly di D. melanogaster, ponendo particolare attenzione al ruolo svolto da questo gene nello sviluppo. Il gene minifly (mfl) appartiene ad una famiglia altamente conservata lungo la scala evolutiva, i cui membri svolgono funzioni essenziali che includono la biogenesi del ribosoma e la pseudouridilazione di RNA target. Mutazioni nell’ortologo umano Dkc1 sono state dimostrate responsabili della patologia ereditaria denominata Discheratosi congenita Xlinked (DC; Heiss et al., 1998), cosicche l’esistenza di un elevato grado di identità fra il gene Dkc1 ed il gene mfl, nonché la forte conservazione funzionale, rendono i mutanti mfl di Drosophila un ottimo sistema modello per la comprensione dei meccanismi molecolari che sono alla base dell’insorgenza di questa patologia. Nel corso del mio lavoro, alcune analisi sperimentali sono state inizialmente concentrate sulla caratterizzazione del mutante ipomorfo mfl1, che rappresenta l’unico mutante vitale allo stadio adulto, essendo gli altri due mutanti disponibili, mfl05 e mfl06, letali durante le fasi di vita larvale (Giordano et al., 1999). Successivamente ho invece analizzato gli effetti determinati dalla parziale inattivazione del gene in linee transgeniche in cui ho attivato, sia in maniera ubiquitaria che localizzata, il silenziamento di mfl mediante RNAi in vivo. In particolare ho ritenuto vantaggioso approfondire l’analisi degli effetti determinati dal silenziamento del gene nell’ala degli individui adulti e nei dischi imaginali dell’ala, che rappresentano un sistema modello ideale sia per lo studio dell’organogenesi che per il differenziamento del tessuto epiteliale (Cohen, 1993). Con particolare interesse ho seguito gli effetti del silenziamento sul pathway di trasduzione del segnale innescato dall’attivazione del gene Notch (N), anch’esso evolutivamente conservato e coinvolto in numerosi ed importanti processi cellulari, quali la specificazione del destino cellulare, il differenziamento, la proliferazione, l’apoptosi, l’adesione, la migrazione, l’angiogenesi e lo sviluppo ed il funzionamento neuronale (Bolos et al., 2007). L’attenta caratterizzazione effettuata sia sui mutanti mfl1 che in seguito a silenziamento genico mediato da RNAi, ha mostrato che la ridotta espressione di mfl riduce sensibilmente l’attivazione di Notch, con conseguenze importanti sul normale processo di sviluppo e differenziamento. Infine, ho analizzato in maggior dettaglio il ruolo regolativo svolto dall’oncogene myc, che e noto innescare l’espressione del gene mfl (Pierce et al., 2008) in Drosophila e del gene Dkc1 (Alawi et al., 2007) nell’uomo. In entrambi gli organismi questi due geni rappresentano infatti i principali target di myc, che e noto regolare l’espressione di molti componenti del macchinario traduzionale (Oskarsson and Trump, 2005; Orian et al., 2003, 2005; Grewal et al., 2005; Gomez-Roman, 2006). In Drosophila, il fenotipo osservato nei mutanti ipomorfi d-mycP0 è quasi sovrapponibile a quello mostrato dai mutanti mfl1, suggerendo che mfl possa rappresentare un importante gene effettore del pathway attraverso cui myc regola la crescita cellulare

Harvesting value from brokerage: individual strategic orientation, structural holes, and performance

In this paper we explore the mechanisms underpinning returns to brokerage positions by considering the role of individuals' strategic orientation toward brokering. We conceptualize individuals' strategic orientations in terms of arbitraging versus collaborating behaviors enacted when occupying a brokerage position. Leveraging a novel dataset collected in a global consumer product company, we theorize and find evidence for the fact that arbitraging and collaborating orientations have differential effects on the relationship between brokerage and performance, significantly impacting on individuals' ability to extract value from brokerage. We discuss the implications of these findings for the structural analysis of informal networks in organizations