1,720,973 research outputs found
L'impronta molecolare di cellule CD34+ di pazienti con mielofibrosi primaria svela alterazioni nell'espressione associate con la patologia
No full textMielofibrosi primaria (PMF), policitemia vera e trombocitemia essenziale sono neoplasie mieloproliferative croniche Philadelphia-negative (MPNs) caratterizzate da una proliferazione clonale che origina dalla cellula staminale e aumentata produzione di cellule mieloidi mature. La PMF è la peggiore fra le MPNs ed è associata con anomala megacariopoiesi, iperproduzione di citochine, fibrosi del midollo osseo (BM), osteosclerosi, angiogenesi ed emopoiesi epatosplenica.
Le informazioni sulle anomalie molecolari delle MPNs sono state limitate fino al 2005 quando fu scoperta la mutazione con guadagno di funzione a carico di JAK2. Da allora molti altri geni mutati sono stati individuati, ciò nonostante essi non rappresentano l’evento mutazionale iniziante ed è chiaro che le basi molecolari delle MPNs non sono state ancora completamente elucidate.
Recentemente, sono stati proposti diversi meccanismi molecolari patogenetici, come l’espressione aberrante di RNAs codificanti e non codificanti.
Per approfondire questo argomento, nella prima fase del progetto abbiamo investigato l’ impronta molecolare di cellule CD34+ in pazienti con PMF, realizzando il profilo di espressione genico su 42 campioni di PMF e 31 controlli sani.
Abbiamo identificato molti geni deregolati potenzialmente coinvolti in alcuni aspetti patogenetici della PMF, come geni correlati con fibrosi del BM (es. MMP9 e TIMP3), regolazione della migrazione cellulare (es. TM4SF1 e MMP8), numerosi fattori di trascrizione e rimodellatori della cromatina coinvolti nel differenziamento mieloide e megacariocitario (es. AFF3, MAF e IKZF2). I campioni di PMF hanno mostrato, inoltre, livelli aumentati di mRNAs adatti come biomarkers o putativi targets molecolari per scopi diagnostici o prognostici. L’espressione dei geni maggiormente upregolati (LCN2, OLFM4, ANXA3, FGR, e LEPR) è stata validata anche su granulociti di PMF, così come i livelli di proteina secreta (OLFM4 e LCN2) sono stati valutati nel siero dei pazienti. I risultati hanno mostrato che questi geni potrebbero essere considerati biomarkers di malattia, in quanto significativamente più elevati nei pazienti.
I geni downregolati, invece, sono stati silenziati in cellule CD34+ normali per costruire modelli di PMF in vitro. Tra questi geni, ci siamo focalizzati sul rimodellatore della cromatina JARID2, in quanto questo processo è frequentemente compromesso nelle MPNs. I nostri dati hanno mostrato che il silenziamento di JARID2 forza il differenziamento emopoietico verso il lineage megacariocitario. Sulla base di tali risultati abbiamo ipotizzato che la downregolazione di JARID2 nelle cellule CD34+ di PMF potrebbe essere coinvolta nella megacariopoiesi anomala che caratterizza questa patologia.
Infine, dato che i lunghi RNAs non-codificanti (lncRNAs) stanno emergendo come regolatori chiave dell’espressione genica in cellule normali e neoplastiche, abbiamo investigato l’espressione dei lncRNAs ANRIL, MEG3 e WT1-antisense (as), già descritti come coinvolti in neoplasie ematologiche, in cellule CD34+ di una diversa coorte di pazienti con PMF. I risultati hanno evidenziato che la maggioranza dei campioni di PMF mostra una co-upregolazione di WT1 e WT1-as rispetto ai controlli. Questi campioni mostrano anche il concomitante aumento di espressione di MEG3. In questi pazienti abbiamo trovato una correlazione fa i livelli di espressione di WT1/WT1-as/MEG3 e il punteggio del Dynamic International Prognostic Scoring System (DIPSS)-plus ed un elevato numero di cellule CD34+ circolanti. In aggiunta il pattern di espressione di CDKN2B/ANRIL ha discriminato un gruppo di pazienti con upregolazione di CDKN2B, e tra questi un sottogruppo con ANRIL downregolato. In particolare, questo gruppo di pazienti presenta un alto grado di fibrosi del BM e la mutazione JAK2V617F. I nostri risultati suggeriscono che anche la deregolata espressione di lncRNAs potrebbe avere un ruolo nella patogenesi e nella progressione della PMFPrimary myelofibrosis (PMF), polycythemia vera and essential thrombocythemia are Philadelphia-negative chronic myeloproliferative neoplasms (MPNs) characterized by stem cell-derived clonal proliferation and increased production of mature myeloid cells. PMF is the worst among the MPNs and is associated with abnormal megakaryopoiesis, cytokine overproduction, bone marrow (BM) fibrosis, osteosclerosis, angiogenesis and hepatosplenic hematopoiesis.
Information on molecular abnormalities of MPNs has been scanty until 2005 with the discovery of the somatic gain-of-function mutation of JAK2. Since then, many other mutated genes were identified, nevertheless they do not represent the primary mutational event and it is clear that the molecular basis of MPNs have not yet been completely elucidated.
Recently, several new molecular pathogenetic mechanisms were proposed, such as the aberrant expression of coding and non-coding RNAs.
In order to address this issue, in the first phase of this project we investigated the molecular signature of CD34+ cells from PMF patients, performing gene expression profiling of 42 PMF samples and 31 healthy controls.
Interestingly, we found many deregulated genes possibly involved in some pathogenetic steps of PMF such as genes related to BM fibrosis (MMP9 and TIMP3) or regulation of cell migration (TM4SF1 and MMP8) as well as a number of transcription factors and chromatin remodelers implicated in myeloid and megakaryocyte commitment (i.e. AFF3, MAF and IKZF2). Moreover, PMF samples exhibited increased levels of several mRNAs suitable as biomarkers or as putative molecular targets for diagnostic or prognostic purposes. Then the expression of the most upregulated genes (LCN2, OLFM4, ANXA3, FGR and LEPR) was validated also in PMF granulocytes, as well as secreted protein (OLFM4 and LCN2) levels were assessed on patients’ serum. These findings demonstrate that these genes could be considered as disease biomarkers, since they were significantly higher in patients.
Conversely, downregulated genes have been silenced in normal CD34+ cells in order to construct in vitro PMF models and to elucidate the possible role in the hematopoietic differentiation. Among those genes, we focused on the chromatin remodeler JARID2, because chromatin remodeling is a process frequently impaired in MPNs. Our data demonstrated that JARID2 silencing enforces the hematopoietic differentiation towards the megakaryocytic lineage. Based on these results we suppose that the downregulation of JARID2 in CD34+ cells from PMF patients could be involved in the abnormal megakaryopoiesis that features this disease.
Finally, since long non-coding RNAs (lncRNAs) are emerging as key regulators of gene expression in normal and cancer cells, we decided to investigate the expression of ANRIL, MEG3 and WT1-antisense lncRNAs, previously described as related to hematological malignancies, in CD34+ cells from a different cohort of PMF patients. The results evidenced that the majority of PMF samples displayed a co-upregulation of WT1 and its antisense RNA compared to controls. These samples also showed an increased MEG3 expression. In these patients, we found a correlation with WT1/WT1-as/MEG3 expression levels and high Dynamic International Prognostic Scoring System (DIPPS) plus score and elevated number of circulating CD34+ cells. Moreover, the expression pattern of CDKN2B/ANRIL distinguished a group of patients characterized by an upregulation of CDKN2B, and among these, a subgroup with downregulated ANRIL. Of note, this group of patients exhibited a high grade of BM fibrosis and the presence of JAK2V617F mutation. Our results suggest that also a deregulated expression of these lncRNAs could play a role in PMF pathogenesis and progression
Genomic landscape of megakaryopoiesis and platelet function defects
Full text linkMegakaryopoiesis is a complex, stepwise process that takes place largely in the bone marrow. At the apex of the hierarchy, hematopoietic stem cells undergo a number of lineage commitment decisions that ultimately lead to the production of polyploid megakaryocytes. On average, megakaryocytes release 1011 platelets per day into the blood that repair vascular injuries and prevent excessive bleeding. This differentiation process is tightly controlled by exogenous and endogenous factors, which have been the topics of intense research in the hematopoietic field. Indeed, a skewing of megakaryocyte commitment and differentiation may entail the onset of myeloproliferative neoplasms and other preleukemic disorders together with acute megakaryoblastic leukemia, whereas quantitative or qualitative defects in platelet production can lead to inherited platelet disorders. The recent advent of next-generation sequencing has prompted mapping of the genomic landscape of these conditions to provide an accurateview of the underlying lesions. The aims of this review are to introduce the physiological pathways of megakaryopoiesis and to present landmark studies on acquired and inherited disorders that target them. These studies have not only introduced a new era in the fields of molecular medicine and targeted therapies but may also provide us with a better understanding ofthemechanismsunderlying normalmegakaryopoiesis and thrombopoiesis that can informeffortsto create alternativesources of megakaryocytes and platelets
miR-382-5p Controls Hematopoietic Stem Cell Differentiation Through the Downregulation of MXD1
No full textmicroRNAs are key regulators of gene expression that control stem cell fate by posttranscriptional downregulation of hundreds of target genes through seed pairing in their 3' untranslated region. In fact, miRNAs tightly regulate fundamental stem cell processes, like self-renewal, proliferation, and differentiation; therefore, miRNA deregulation may contribute to the development of solid tumors and hematological malignancies. miR-382-5p has been found to be upregulated in patients with myeloid neoplasms, but its role in normal hematopoiesis is still unknown. In this study, we demonstrated that miR-382-5p overexpression in CD34(+) hematopoietic stem/progenitor cells (HSPCs) leads to a significant decrease of megakaryocyte precursors coupled to increase of granulocyte ones. Furthermore, by means of a computational analysis using different prediction algorithms, we identified several putative mRNA targets of miR-382-5p that are downregulated upon miRNA overexpression (ie, FLI1, GATA2, MAF, MXD1, RUNX1, and SGK1). Among these, we validated MXD1 as real target of miR-382-5p by luciferase reporter assay. Finally, we showed that MXD1 knockdown mimics the effects of miR-382-5p overexpression on granulocyte and megakaryocyte differentiation of CD34(+) cells. Overall, our results demonstrated that miR-382-5p expression favors the expansion of granulocyte lineage and impairs megakaryocyte commitment through MXD1 downregulation. Therefore, our data showed for the first time that the miR-382-5p/MXD1 axis plays a critical role in myelopoiesis by affecting the lineage choice of CD34(+) HSPCs
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
