1,721,023 research outputs found
Microrna coinvolti nello sviluppo embrionale e nella progressione tumorale
Full text linkMicroRNAs(miRNAs) are small non-coding RNA that regulate gene expression at the posttranscriptional level. MiRNAs are involved in many biological processes, as embryonic development, cellular differentiation and proliferation.
Genes involved in embryonic development are often used aberrantly by cancer cells: for example, the TGF-? cascade has a key role during early development in vertebrates, but during cancer progression TGF-? controls proliferation and invasion.
In the first part of this thesis we characterized miR-15 and miR-16 as microRNAs critical for early embryonic development. Indeed, we demonstrated that they regulate the induction of the Spemann Organizer, a tissue controlling axis formation and neural induction in Xenopus embryos (Martello et al., 2007).
The second part of this thesis is about a microRNA family with oncogenic activity: miR-103 and -107 are overexpressed in different tumor types and can control the epithelial plasticity and cellular motility, two main aspects of the metastatic progression.I microRNA (miRNA) sono una famiglia di piccoli RNA non codificanti, in grado di inibire l’espressione genica a livello post-trascrizionale; i miRNA sono coinvolti in numerosi processi biologici, che vanno dallo sviluppo embrionale al controllo della proliferazione cellulare.
E’ interessante osservare come spesso la cellula tumorale utilizzi in maniera aberrante dei programmi genici propri dell’embrione; ad esempio il segnale TGF-? ha un ruolo chiave durante lo sviluppo embrionale precoce, ma nel contesto tumorale regola sia la proliferazione e che l’invasività cellulare.
Nella prima parte (A) di questa tesi di dottorato ci siamo occupati di miR-15 e miR-16, per i quali ho identificato un ruolo durante lo sviluppo embrionale precoce. Abbiamo dimostrato come miR-15 e miR-16 regolino la formazione dell’Organizzatore di Spemann, una struttura che controlla la formazione degli assi corporei e del sistema nervoso in embrioni di Xenopus laevis (Martello et al., 2007).
La seconda parte (B) di questa tesi è dedicata ad uno studio, ancora non pubblicato, su una famiglia di miRNA a potenziale attività oncogenica, miR-103 e miR-107. Questi geni sono espressi ad alti livelli in diversi tipi tumorali e sono in grado di controllare la plasticità epiteliale e la motilità cellulare, due aspetti cruciali nel processo metastatico
Identification of the missing pluripotency mediator downstream of leukaemia inhibitory factor
Full text linkSelf-renewal of pluripotent mouse embryonic stem (ES) cells is sustained by the cytokine leukaemia inhibitory factor (LIF) acting through the transcription factor Stat3. Several targets of Stat3 have previously been identified, most notably the reprogramming factor Klf4. However, such factors are neither required nor sufficient for the potent effect of LIF. We took advantage of Stat3 null ES cells to confirm that Stat3 mediates the self-renewal response to LIF. Through comparative transcriptome analysis intersected with genome location data, we arrived at a set of candidate transcription factor effectors. Among these, Tfcp2l1 (also known as Crtr-1) was most abundant. Constitutive expression of Tfcp2l1 at levels similar to those induced by LIF effectively substituted for LIF or Stat3 in sustaining clonal self-renewal and pluripotency. Conversely, knockdown of Tfcp2l1 profoundly compromised responsiveness to LIF. We further found that Tfcp2l1 is both necessary and sufficient to direct molecular reprogramming of post-implantation epiblast stem cells to naïve pluripotency. These results establish Tfcp2l1 as the principal bridge between LIF/Stat3 input and the transcription factor core of naïve pluripotency
PsiNorm: a scalable normalization for single-cell RNA-seq data
Full text linkMotivation: Single-cell RNA sequencing (scRNA-seq) enables transcriptome-wide gene expression measurements at single-cell resolution providing a comprehensive view of the compositions and dynamics of tissue and organism development. The evolution of scRNA-seq protocols has led to a dramatic increase of cells throughput, exacerbating many of the computational and statistical issues that previously arose for bulk sequencing. In particular, with scRNA-seq data all the analyses steps, including normalization, have become computationally intensive, both in terms of memory usage and computational time. In this perspective, new accuratemethods able to scale efficiently are desirable. Results: Here, we propose PsiNorm, a between-sample normalization method based on the power-law Pareto distribution parameter estimate. Here, we show that the Pareto distribution well resembles scRNA-seq data, especially those coming from platforms that use unique molecular identifiers. Motivated by this result, ..
Monitoring smad activity in vivo using the xenopus model system
No full textThe embryo of the African clawed frog Xenopus laevis plays a central role in the field of cell and developmental biology. One of the strengths of Xenopus as model system lies in the high degree of conservation between amphibians and mammals in the molecular mechanisms controlling tissue patterning and differentiation. As such, many signaling cascades were first investigated in frog embryos and then confirmed in mouse and/or human cells. The TGF-β signaling cascade greatly benefited from this model system. Here we review the overall logic and experimental planning for studying Smad activity in vivo in the context of Xenopus embryonic development, and provide a guide for the interpretation of the results
MicroRNA control of signal transduction
No full textMicroRNAs (miRNAs) are integral elements in the post-transcriptional control of gene expression. After the identification of hundreds of miRNAs, the challenge is now to understand their specific biological function. Signalling pathways are ideal candidates for miRNA-mediated regulation owing to the sharp dose-sensitive nature of their effects. Indeed, emerging evidence suggests that miRNAs affect the responsiveness of cells to signalling molecules such as transforming growth factor-beta, WNT, Notch and epidermal growth factor. As such, miRNAs serve as nodes of signalling networks that ensure homeostasis and regulate cancer, metastasis, fibrosis and stem cell biology
Using Microfluidics to Generate Human Naïve and Primed Pluripotent Stem Cells
No full textHuman induced pluripotent stem cells (iPSCs) are generated from somatic cells by the expression of a cocktail of transcription factors, and iPSCs have the capacity to generate in vitro all cell types of the human body. In addition to primed (conventional) iPSCs, several groups recently reported the generation of human naïve iPSCs, which are in a more primitive developmental state and have a broader developmental potential, as shown by their ability to form cells of the placenta. Human iPSCs have broad medical potential but their generation is often time-consuming, not scalable and requires viral vectors or stable genetic manipulations. To overcome such limitations, we developed protocols for high-efficiency generation of either conventional or naïve iPSCs by delivery of messenger RNAs (mRNAs) using a microfluidic system. In this protocol we describe how to produce microfluidic devices, and how to reprogram human somatic cells into naïve and primed iPSCs using these devices. We also describe how to transfer the iPSC colonies from the microfluidic devices over to standard multiwell plates for subsequent expansion of the cultures. Our approach does not require stable genetic modifications, is reproducible and cost-effective, allowing to produce patient-specific iPSCs for cell therapy, disease modeling, and in vitro developmental studies
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